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Sample records for astigmatism

  1. Astigmatism

    Science.gov (United States)

    ... uncorrected astigmatism in only one eye may cause amblyopia . When to Contact a Medical Professional Call your ... any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should ...

  2. Astigmatism in cataract surgery.

    Science.gov (United States)

    Luntz, M. H.; Livingston, D. G.

    1977-01-01

    We report on our investigation into astigmatism in 40 eyes following a corneal cataract incision closed with a continuous 10/0 nylon monofilament suture (Ethilon). Immediately after surgery there was astigmatism caused by the nylon suture (suture-induced astigmatism), its severity depending on the tightness of the suture. It ranged from 1 to 10-5 dioptres, the mean value 4-09 dioptres with a standard deviation of +/-2-5. Removing the nylon suture eliminated this astigmatism and within a few weeks the corneal astigmatism correction in 48% of eyes returned to the preoperative level. In 80% of eyes the difference between the final postoperative corneal astigmatism (4 months after removing the continuous suture) and the preoperative astigmatism was 0-75 dioptres or less and the maximum change was 1-5 dioptres. In 40% of eyes the axis of the cylinder changed from a horizontal to an oblique axis but did not change from a with- to against-the-rule axis. The degree of astigmatism remained constant while the suture was in place and in 50% of eyes was equal to or less than 3 dioptres. The mean of the spherical equivalents was 11-31 dioptres with a standard deviation of +/-1-25. A spectacle correction 14 days after operation prescribed either as the mean spherical equivalent (11-50 dioptres) or according to the patient's refraction will give satisfactory vision until the suture is removed 4 months after operation. The degree of astigmatism following a corneal section and continuous nylon suture compares very favourably with astigmatism following other suturing techniques for cataract. Images PMID:326304

  3. [Postoperative induced astigmatism].

    Science.gov (United States)

    Nicula, C; Nicula, D

    2000-01-01

    Is to evaluate the astigmatism induced by cataract surgery, ethiological factors and ways of prophilaxies and treatment. We followed a number of 211 eyes operated for cataract by planned extracapsular extraction with intraocular lens implantation, in Ophthalmological Clinic from Cluj-Napoca. All the pacients had limbal incision and the suture was performed with 9.0 suture, after the operation the treatment consisted in local drops with steroids. REZULTS: The astigmatism induced by the surgery was direct in 53.08% of cases and indirect in 46.92%. The position of the axes was 0-900 in 72.51% and oblique in 27.48%. The optical correction of astigmatism was with combined spherocylinder glases in 57.34% and only with cilinder in 42.65% of cases. 1. The induced astigmatism by cataract surgery is in relation with the incision, suture and IOL. 2. Correction of astigmatism is possible with optical correction, repearing the suture or with refractive surgery. 3. The prevention of astigmatism over 1.5 D is by using Troutmann keratometer and to evidence the congenital astigmatism.

  4. Corneal astigmatism following cataract extraction.

    Science.gov (United States)

    Wishart, M S; Wishart, P K; Gregor, Z J

    1986-01-01

    The changes in corneal curvature in the first six months after cataract extraction were studied by performing sequential keratometry on a group of 57 patients. 8/0 Virgin silk interrupted sutures were used for the closure of corneoscleral incisions, and 10/0 monofilament tied in double running (bootlace) or single running (continuous) fashion was used for corneal wound closure. A high degree of with-the-rule astigmatism was evident in all patients two weeks postoperatively, but thereafter the character of the astigmatism produced by 8/0 virgin silk and 10/0 monofilament closure was quite different: in the 8/0 virgin silk group there was an early and pronounced shift in the axis of astigmatism to against-the-rule, whereas in the 10/0 monofilament group there was little further change in the astigmatism unless the sutures were removed. Wound compression and wound gape as factors responsible for these changes are discussed. PMID:3539177

  5. Myopic astigmatism and presbyopia trial.

    Science.gov (United States)

    Savage, Howard; Rothstein, Micah; Davuluri, Geeta; El Ghormli, Laure; Zaetta, Deneen M

    2003-05-01

    No prospective double-masked study has evaluated whether low astigmatism benefits or harms patients with presbyopia, whose intermediate and near vision might theoretically benefit from enhanced depth of focus provided by astigmatism. The purpose of the first Myopic Astigmatism and Presbyopia (MAP I) study was to determine whether low myopic astigmatism enhances or harms the visual acuity, stereopsis, or quality of life in patients with presbyopia. Prospective, randomized, double-masked, crossover design clinical trial. Fifteen patients with presbyopia aged 45 to 68 years were recruited from an academic center population. These patients were given a baseline eye examination, including manifest refraction, Early Treatment of Diabetic Retinopathy Study (ETDRS) logarithm of minimal angle of resolution (logMAR) visual acuity at distance, intermediate, and near, accommodative amplitudes, and stereo vision. Each patient was then cycled in random order through three masked pairs of soft contact lenses. The power of each contact lens pair was calculated by the subtraction method to maintain a spherical equivalent of -0.5 diopters, while providing either no astigmatism (spherical arm, SPH), 1 diopter of with-the-rule (WTR) astigmatism, or 1 diopter of against-the-rule (ATR) astigmatism. Actual refractive errors produced were measured by masked examiner. Outcomes measured at the end of 1 week of usage of each contact lens arm were binocular (ETDRS) logMAR visual acuity at three distances (far [4 m], intermediate [1 m], and near [33cm]); near stereoacuity, using the quantitative Titmus Stereotest; and quality of life, measured using the Refractive Status and Vision Profile (RSVP), a standardized questionnaire. Visual acuity results across the three arms were similar. However, 1-m logMAR visual acuity was better for the spherical arm than either astigmatic arm (-0.06 SPH, +0.01 WTR, +0.02 ATR). Near (33 cm) and distance (4 m) acuities were similar across arms. Stereoacuity was

  6. CAUSES OF HIGH ASTIGMATISM AFTER PENETRATING KERATOPLASTY

    NARCIS (Netherlands)

    HOPPENREIJS, VPT; VANRIJ, G; BEEKHUIS, WH; RIJNEVELD, WJ; RINKELVANDRIEL, E

    1993-01-01

    We retrospectively evaluated the factors which might have caused excessive corneal astigmatism after penetrating keratoplasty (PKP) in 29 eyes, in which surgical correction of astigmatism was indicated. In 18 eyes high astigmatism (5 diopters or more) existed before suture removal probably due to

  7. [Postoperative astigmatism secondary to cataract surgery].

    Science.gov (United States)

    Cornelia, Jelic

    2003-01-01

    The purpose was to study the cases operated by the extracapsular extraction with the posterior chamber implant from the viewpoint of postoperative astigmatism. We studied the cases with no postoperative complications along three years (1999-2001). In all cases we noted the placement, length and type of the incision, the suture (by 3 or 5 radiar suture) and the tension of the eye-ball in the time of suture. We determined the refraction at 2-3 and 6 weeks postoperatory and note the astigmatism (by the rule or against the rule) and its value in D. The postoperative astigmatism was found in 246 cases. Depending on the placement, length and type of the incision the postoperative astigmatism was found in 86.18% cases with the rule and in 13.82% cases against the rule, 54.72% postoperative astigmatism with the rule by 1.5-3 D. If we sutured with three radiar suture the astigmatism was with the rule in 86.88% cases, 52.82% astigmatism by 1.5-3D. If we sutured with 5 radiar suture the astigmatism was with the rule in 85.95% cases, 55.35% astigmatism by 1.5-3D. Normotension determined astigmatism by the rule in 90.16% cases and 60.10% by 1.5-3D. The suture with Vicryl 8.00 determined astigmatism by the rule in 86.18% cases and 54.72% was between 1.5-3D. Postoperative astigmatism depends by many factors more or less predictable. Astigmatism by the rule was found in majority of the cases and it was between 1.5-3D and it was controlled by glasses. Postoperative astigmatism tends to become history in new period of modern cataract surgery methods.

  8. Bilateral femtosecond laser-enabled intrastromal astigmatic keratotomy to correct high post-penetrating keratoplasty astigmatism.

    Science.gov (United States)

    Viswanathan, Deepa; Kumar, Nikhil L

    2013-12-01

    A 35-year-old man presented with bilateral high astigmatism following penetrating keratoplasties performed for advanced keratoconus. Femtosecond laser-enabled intrastromal astigmatic keratotomy was performed, resulting in a significant reduction in corneal astigmatism. At 4 months, the corneal astigmatism continued to decrease. The visual acuity, refraction, and serial corneal topographic data are presented. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  9. [Astigmatism after keratoplasty: influence of orthotopic transplantation].

    Science.gov (United States)

    Feuerstacke, J; Hellwinkel, O; Naydis, I; Linke, S; Klemm, M

    2014-09-01

    Patients undergoing corneal transplantation often suffer from postoperative reduced vision due to high astigmatism. This retrospective study analyzed the influence of heterotopic or orthotopic transplantation on astigmatism and visual outcome. In this study 373 eyes of 334 patients were analyzed. Group 1 (OT) contained 186 eyes, which underwent orthotopic transplantation (side of recipient and donor corresponded), whereas group 2 (HT) included 187 heterotopic keratoplasties (donor cornea placed in the recipient's contralateral side). After 1, 3, 6, 12 and 24 months the median of keratometric astigmatism, objective astigmatism, topographic astigmatism and best corrected visual acuity (BCVA) were assessed and compared between groups. The long-term results showed no statistically significant differences regarding keratometric and objective astigmatism, whereas topographic astigmatism differed significantly (p = 0.04) after 3 months. We observed a lower astigmatism of 5.7 dpt (range 3.08-7.78 dpt) in group OT than in the group HT with 7.1 dpt (range 3.9-10.7 dpt). No differences were found at the other time points. The BCVA showed a significantly better effect after 1 month (p = 0.01) in the OT group of 0.2 (0.1-0.3) than in HT group of 0.1 (0.05/0.25). In the postoperative course no additional significant dissimilarities were documented. Heterotopic and orthotopic keratoplasty show no significant long-term differences in astigmatism and visual outcom.

  10. Management of post-keratoplasty astigmatism.

    Science.gov (United States)

    Fares, Usama; Sarhan, Abdel Rahman S; Dua, Harminder S

    2012-11-01

    Post-keratoplasty astigmatism remains a challenge for corneorefractive surgeons. While maintaining a healthy graft is the most crucial issue in keratoplasty procedures, astigmatism is a limiting factor in the visual rehabilitation of otherwise successful corneal grafts. The management of post-keratoplasty astigmatism takes place at 2 stages: when sutures are still present at the graft-host junction and when all sutures have been removed. Excessive suture-in post-keratoplasty astigmatism is usually managed by selective suture manipulation, ie, suture adjustment and/or suture removal along the steep meridian of astigmatism. A small amount of suture-out post-keratoplasty astigmatism can be managed by spectacles. Higher magnitudes of astigmatism can be addressed by contact lenses or surgical intervention, such as relaxing and compressing procedures. Laser lamellar refractive surgery can also be used to manage post-keratoplasty astigmatism, and toric phakic intraocular lenses have recently been recommended. In this review, we discuss the etiology and management of post-keratoplasty astigmatism and provide recommendations and tips to minimize it. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  11. Relationship between preoperative axis of astigmatism and postoperative astigmatic change after superior scleral incision phacoemulsification.

    Science.gov (United States)

    Lyhne, N; Hansen, T E; Corydon, L

    1998-07-01

    To evaluate the effect of the preoperative axis of astigmatism on the outcome of corneal astigmatism after sutured 5.2 to 5.7 mm superior incision phacoemulsification. Departments of Opthalmology, Odense and Vejle Hospitals, Denmark. Seventy-three consecutive patients with preoperative corneal astigmatism of 2.0 diopters (D) or less, axial length between 20.0 and 25.5 mm, and no eye disease except cataract were grouped according to preoperative with-the-rule (WTR) or against-the-rule (ATR) astigmatism. The keratometric cylinder, induced keratometric cylinder (subtraction), and induced cylinder (Jaffe) were measured and calculated 10 to 12 months postoperatively. The postoperative keratometric cylinder and induced keratometric cylinder were significantly higher in the ATR group (P astigmatism. The findings support using temporal incision in cases with a preoperative ATR axis of astigmatism.

  12. Visual Motor and Perceptual Task Performance in Astigmatic Students

    Directory of Open Access Journals (Sweden)

    Erin M. Harvey

    2017-01-01

    Full Text Available Purpose. To determine if spectacle corrected and uncorrected astigmats show reduced performance on visual motor and perceptual tasks. Methods. Third through 8th grade students were assigned to the low refractive error control group (astigmatism < 1.00 D, myopia < 0.75 D, hyperopia < 2.50 D, and anisometropia < 1.50 D or bilateral astigmatism group (right and left eye ≥ 1.00 D based on cycloplegic refraction. Students completed the Beery-Buktenica Developmental Test of Visual Motor Integration (VMI and Visual Perception (VMIp. Astigmats were randomly assigned to testing with/without correction and control group was tested uncorrected. Analyses compared VMI and VMIp scores for corrected and uncorrected astigmats to the control group. Results. The sample included 333 students (control group 170, astigmats tested with correction 75, and astigmats tested uncorrected 88. Mean VMI score in corrected astigmats did not differ from the control group (p=0.829. Uncorrected astigmats had lower VMI scores than the control group (p=0.038 and corrected astigmats (p=0.007. Mean VMIp scores for uncorrected (p=0.209 and corrected astigmats (p=0.124 did not differ from the control group. Uncorrected astigmats had lower mean scores than the corrected astigmats (p=0.003. Conclusions. Uncorrected astigmatism influences visual motor and perceptual task performance. Previously spectacle treated astigmats do not show developmental deficits on visual motor or perceptual tasks when tested with correction.

  13. Perceptual adaptation to the correction of natural astigmatism.

    Directory of Open Access Journals (Sweden)

    Maria Vinas

    Full Text Available The visual system adjusts to changes in the environment, as well as to changes within the observer, adapting continuously to maintain a match between visual coding and visual environment. We evaluated whether the perception of oriented blur is biased by the native astigmatism, and studied the time course of the after-effects following spectacle correction of astigmatism in habitually non-corrected astigmats.We tested potential shifts of the perceptual judgments of blur orientation in 21 subjects. The psychophysical test consisted on a single interval orientation identification task in order to measure the perceived isotropic point (astigmatism level for which the image did not appear oriented to the subject from images artificially blurred with constant blur strength (B=1.5 D, while modifying the orientation of the blur according to the axis of natural astigmatism of the subjects. Measurements were performed after neutral (gray field adaptation on naked eyes under full correction of low and high order aberrations. Longitudinal measurements (up to 6 months were performed in three groups of subjects: non-astigmats and corrected and uncorrected astigmats. Uncorrected astigmats were provided with proper astigmatic correction immediately after the first session. Non-astigmats did not show significant bias in their perceived neutral point, while in astigmatic subjects the perceived neutral point was significantly biased, typically towards their axis of natural astigmatism. Previously uncorrected astigmats shifted significantly their perceived neutral point towards more isotropic images shortly (2 hours after astigmatic correction wear, and, once stabilized, remained constant after 6 months. The shift of the perceived neutral point after correction of astigmatism was highly correlated with the amount of natural astigmatism.Non-corrected astigmats appear to be naturally adapted to their astigmatism, and astigmatic correction significantly changes their

  14. Long-term follow-up of astigmatic keratotomy for corneal astigmatism after penetrating keratoplasty.

    Science.gov (United States)

    Böhringer, Daniel; Dineva, Nina; Maier, Philip; Birnbaum, Florian; Kirschkamp, Thomas; Reinhard, Thomas; Eberwein, Philipp

    2016-11-01

    To report the long-term stability of paired arcuate corneal keratotomies (AKs) in patients with high regular postpenetrating keratoplasty astigmatism. Retrospective chart review of best-corrected visual acuity, refraction and keratometric values of 41 eyes with AK between 2003 and 2012. Magnitude of median target induced astigmatism vector was 9.2 dioptres (Dpt). We reached a median magnitude of surgically induced astigmatism vector of 9.81 Dpt and a median magnitude of difference vector of 5.5 Dpt. In keratometry, we achieved a net median astigmatism reduction by 3.3 Dpt. The average correction index was 1.14, showing a slight overcorrection. Irregularity of keratometric astigmatism increased by 0.6 Dpt, and spherical equivalent changed by 1.75 Dpt. Monocular best spectacle corrected visual acuity increased from preoperatively 20/63 (0.5 logMAR) to 20/40 (0.3 logMAR) postoperatively. Median gain on the ETDRS chart was two lines. Long-term follow-up showed a median keratometric astigmatic increase by 0.3 Dpt per year. Arcuate corneal keratotomies is a safe and effective method to reduce high regular corneal astigmatism following penetrating keratoplasty but has limited predictability. The long-term follow-up shows an increase of keratometric astigmatism by 0.3 Dpt/year, equalizing the surgical effect after 10 years. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  15. [Surgically induced astigmatism after cataract phacoemulsification].

    Science.gov (United States)

    Bilińska, Ewa; Wesołek-Czernik, Agata; Synder, Aleksandra; Omulecki, Wojciech

    2004-01-01

    To evaluate the astigmatic effect after phacoemulsification depending on size and location of incision. Three groups of 30 patients each: In 1st group with scleral tunnel incision enlarged to 6 mm with continuous cross-like suture at 12 o'clock; In 2nd group with 3.2 mm scleral incision without suture at 12 o'clock; In 3rd group with 3.2 mm superotemporal incision in clear cornea, no suture. Postoperative astigmatism was examined by keratometry after 1 day, 1 week and 1 and 3 months post surgery. Surgically induced astigmatism was calculated by polar values method. After 3 months observation the lowest mean postoperative corneal astigmatism was achieved in group III. The SIA was 0.71 in group III, 1.08 in group I and 0.95 in group II. The differences between group III and groups I, II were statistically significant. Surgically induced astigmatism can be minimized with incision in clear cornea and no suture.

  16. Combined astigmatic keratotomy and conductive keratoplasty to correct high corneal astigmatism.

    Science.gov (United States)

    Sy, Mary Ellen; Kovoor, Timmy A; Tannan, Anjali; Choi, Daniel; Deng, Sophie X; Danesh, Jennifer; Hamilton, D Rex

    2015-05-01

    To determine the safety, efficacy, and predictability of combined astigmatic keratotomy (AK) and conductive keratoplasty (CK) for treating high corneal astigmatism. University of California-Los Angeles, Los Angeles, California, USA. Retrospective case series. From January 1, 2004, to December 31, 2009, AK and CK were performed in eyes with corneal astigmatism of 5.0 diopters (D) or more after keratoplasty or trauma. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, spherical equivalent (SE), defocus equivalent, mean astigmatism, efficacy index, and complications were evaluated. In 11 eyes of 11 patients, the mean UDVA improved from 1.54 logMAR ± 0.50 (SD) preoperatively to 0.69 ± 0.62 logMAR 3 months postoperatively (P astigmatism decreased from 10.25 ± 4.71 D to 4.31 ± 2.34 D (P astigmatism showed a statistically significant decrease. The efficacy index was 0.82. One case of wound gape after AK required suturing. No infectious keratitis, corneal perforation, or graft rejection occurred. Results indicate that combined AK and CK is safe and effective for correcting high corneal astigmatism after surgery or trauma. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  17. Three methods for correction of astigmatism during phacoemulsification

    Directory of Open Access Journals (Sweden)

    Hossein Mohammad-Rabei

    2016-01-01

    Conclusion: There was no significant difference in astigmatism reduction among the three methods of astigmatism correction during phacoemulsification. Each of these methods can be used at the discretion of the surgeon.

  18. Correlation of major components of ocular astigmatism in myopic patients.

    Science.gov (United States)

    Mohammadpour, Mehrdad; Heidari, Zahra; Khabazkhoob, Mehdi; Amouzegar, Afsaneh; Hashemi, Hassan

    2016-02-01

    To investigate the correlation of major components of ocular astigmatism in myopic patients in an academic hospital. This cross-sectional study was conducted on 376 eyes of 188 patients who were referred to Farabi Eye Hospital for refractive surgery. Preoperative examinations including refraction and corneal topography were performed for all candidates to measure refractive and corneal astigmatism. Ocular residual astigmatism was calculated using vector analysis. Pearson's correlation and ANOVA analysis were used to evaluate the strength of the association between different types of astigmatism. Both eyes were defined as cluster and the Generalized Estimating Equations (GEE) analysis were performed. Mean age of 119 women (63.3%) and 69 men (36.7%) was 27.8 ± 5.7 years. Mean refractive error based on spherical equivalent was -3.59 ± 1.95D (range, -0.54 to -10.22D). Mean refractive and corneal astigmatism was 1.97 ± 1.3D and 1.85 ± 1.01D, respectively. Mean amount of ORA was 0.65 ± 0.36D.There was a significant correlation between ORA and refractive astigmatism(r=0.23, p<0.001), corneal and refractive astigmatism (r=0.91, p<0.001) and a weak correlation between ORA and corneal astigmatism (r=0.13, p=0.014). There was a significant correlation between J0 and J45 values of ORA and corneal astigmatism (p<0.001). There is a significant correlation between ORA and refractive astigmatism, refractive and corneal astigmatism and a weak correlation between ORA and corneal astigmatism in refractive surgery candidates. Identifying the type of astigmatism and preoperative measurement of ocular residual astigmatism is highly recommended prior to any refractive surgery, especially in cases with significant astigmatism. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Rectangular Laser Resonators with Astigmatic Compensation

    DEFF Research Database (Denmark)

    Skettrup, Torben

    2005-01-01

    An investigation of rectangular resonators with a view to the compensation of astigmatism has been performed. In order to have beam waists placed at the same positions in the tangential and sagittal planes, pairs of equal mirrors were considered. It was found that at least two concave mirrors are...

  20. Higher Order Aberration and Astigmatism in Children with Hyperopic Amblyopia.

    Science.gov (United States)

    Choi, Seung Kwon; Chang, Ji Woong

    2016-02-01

    To investigate the changes in corneal higher-order aberration (HOA) during amblyopia treatment and the correlation between HOA and astigmatism in hyperopic amblyopia children. In this retrospective study, a total of 72 eyes from 72 patients ranging in age from 38 to 161 months were included. Patients were divided into two groups based on the degree of astigmatism. Corneal HOA was measured using a KR-1W aberrometer at the initial visit and at 3-, 6-, and 12-month follow-ups. Correlation analysis was performed to assess the association between HOA and astigmatism. A total of 72 patients were enrolled in this study, 37 of which were classified as belonging to the higher astigmatism group, while 35 were assigned to the lower astigmatism group. There was a statistically significant difference in success rate between the higher and lower astigmatism groups. In both groups, all corneal HOAs were significantly reduced during amblyopia treatment. When comparing the two groups, a significant difference in coma HOA at the 12-month follow-up was detected (p = 0.043). In the Pearson correlation test, coma HOA at the 12-month follow-up demonstrated a statistically significant correlation with astigmatism and a stronger correlation with astigmatism in the higher astigmatism group than in the lower astigmatism group (coefficient values, 0.383 and 0.284 as well as p = 0.021 and p = 0.038, respectively). HOA, particularly coma HOA, correlated with astigmatism and could exert effects in cases involving hyperopic amblyopia.

  1. [Astigmatic keratotomy with the femtosecond laser: correction of high astigmatisms after keratoplasty].

    Science.gov (United States)

    Kook, D; Bühren, J; Klaproth, O K; Bauch, A S; Derhartunian, V; Kohnen, T

    2011-02-01

    The purpose of this study was to evaluate a novel technique for the correction of postoperative astigmatism after penetrating keratoplasty with the use of the femtosecond laser creating astigmatic keratotomies (femto-AK) in the scope of a retrospective case series. Clinical data of ten eyes of nine patients with high residual astigmatism after penetrating keratoplasty undergoing paired femto-AK using a 60-kHz femtosecond laser (IntraLase™, AMO) were analyzed. A new software algorithm was used to create paired arcuate cuts deep into the donor corneal button with different cut angles. Target values were refraction, uncorrected visual acuity, best corrected visual acuity, topographic data (Orbscan®, Bausch & Lomb, Rochester, NY, USA), and corneal wavefront analysis using Visual Optics Lab (VOL)-Pro 7.14 Software (Sarver and Associates). Vector analysis was performed using the Holladay, Cravy and Koch formula. Statistical analysis was performed to detect significances between visits using Student's t test. All procedures were performed without any major complications. The mean follow-up was 13 months. The mean patient age was 48.7 years. The preoperative mean uncorrected visual acuity (logMAR) was 1.27, best corrected visual acuity 0.55, mean subjective cylinder -7.4 D, and mean topometric astigmatism 9.3 D. The postoperative mean uncorrected visual acuity (logMAR) was 1.12, best corrected visual acuity 0.47, mean subjective cylinder -4.1 D, and mean topometric astigmatism 6.5 D. Differences between corneal higher order aberrations showed a high standard deviation and were therefore not statistically significant. Astigmatic keratotomy using the femtosecond laser seems to be a safe and effective tool for the correction of higher corneal astigmatisms. Due to the biomechanical properties of the cornea and missing empirical data for the novel femto-AK technology, higher numbers of patients are necessary to develop optimal treatment nomograms.

  2. IntraLase-enabled astigmatic keratotomy for post-keratoplasty astigmatism: on-axis vector analysis.

    Science.gov (United States)

    Kumar, Nikhil L; Kaiserman, Igor; Shehadeh-Mashor, Raneen; Sansanayudh, Wiwan; Ritenour, Rusty; Rootman, David S

    2010-06-01

    To determine the refractive predictability, stability, efficacy, and complication rate of femtosecond laser-enabled astigmatic keratotomy for post-keratoplasty astigmatism. A retrospective case series (pilot study). Thirty-seven eyes of 34 patients. All eyes underwent IntraLase-enabled astigmatic keratotomy for high astigmatism (>5 diopters [D]) after penetrating keratoplasty. Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), manifest refraction, higher-order aberrations, and complications. Mean follow-up was for 7.2 months. Uncorrected visual acuity improved from a mean of 1.08+/-0.34 logarithm of the minimum angle of resolution preoperatively to a mean of 0.80+/-0.42 postoperatively (P=0.0016). Best-corrected visual acuity improved from a mean of 0.45+/-0.27 preoperatively to 0.37+/-0.27 postoperatively (P=0.018). The defocus equivalent was significantly reduced by more than 1 D (P=0.025). The value of absolute astigmatism was reduced from 7.46+/-2.70 D preoperatively to 4.77+/-3.29 D postoperatively (P=0.0001). Higher-order aberrations were significantly increased. The efficacy index was 0.6+/-0.6. There were no cases of perforation, wound dehiscence, or infectious keratitis. Three eyes (8%) experienced an episode of graft rejection. Overcorrection occurred in 9 eyes (24%). IntraLase-enabled astigmatic keratotomy is an effective treatment for high astigmatism after penetrating keratoplasty with an encouraging refractive predictability. Future studies may help refine the treatment parameters required to achieve reduction of cylinder with greater accuracy. Copyright 2010 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  3. Beveled femtosecond laser astigmatic keratotomy for the treatment of high astigmatism post-penetrating keratoplasty.

    Science.gov (United States)

    Cleary, Catherine; Tang, Maolong; Ahmed, Habeeb; Fox, Martin; Huang, David

    2013-01-01

    To use beveled femtosecond laser astigmatic keratotomy (FLAK) incisions to treat high astigmatism after penetrating keratoplasty. Paired FLAK incisions at a bevel angle of 135 degrees, 65% to 75% depth, and arc lengths of 60 to 90 degrees were performed using a femtosecond laser. One case of perpendicular FLAK was presented for comparison. Vector analysis was used to calculate the changes in astigmatism. Fourier domain optical coherence tomography was used to examine incision morphology. Wound gaping requiring suturing was observed in the case of perpendicular FLAK. Six consecutive cases of beveled FLAK were analyzed. Fourier domain optical coherence tomography showed that beveled FLAK caused a mean forward shift of Bowman layer anterior to the incisions of 126 ± 38 μm, with no wound gaping. The mean magnitude of preoperative keratometric astigmatism was 9.8 ± 2.9 diopters (D), and postoperatively it was 4.5 ± 3.2 D (P astigmatism. Early postoperative changes stabilized within 1 month in most patients. Further studies are needed to assess long-term outcomes.

  4. Beveled Femtosecond Laser Astigmatic Keratotomy for the Treatment of High Astigmatism Post–Penetrating Keratoplasty

    Science.gov (United States)

    Cleary, Catherine; Tang, Maolong; Ahmed, Habeeb; Fox, Martin; Huang, David

    2013-01-01

    Purpose To use beveled femtosecond laser astigmatic keratotomy (FLAK) incisions to treat high astigmatism after penetrating keratoplasty. Methods Paired FLAK incisions at a bevel angle of 135 degrees, 65% to 75% depth, and arc lengths of 60 to 90 degrees were performed using a femtosecond laser. One case of perpendicular FLAK was presented for comparison. Vector analysis was used to calculate the changes in astigmatism. Fourier domain optical coherence tomography was used to examine incision morphology. Results Wound gaping requiring suturing was observed in the case of perpendicular FLAK. Six consecutive cases of beveled FLAK were analyzed. Fourier domain optical coherence tomography showed that beveled FLAK caused a mean forward shift of Bowman layer anterior to the incisions of 126 ± 38 μm, with no wound gaping. The mean magnitude of preoperative keratometric astigmatism was 9.8 ± 2.9 diopters (D), and postoperatively it was 4.5 ± 3.2 D (P incisions at varied depth are effective in the management of postkeratoplasty astigmatism. Early postoperative changes stabilized within 1 month in most patients. Further studies are needed to assess long-term outcomes. PMID:22968362

  5. Cat keratoplasty wound healing and corneal astigmatism.

    Science.gov (United States)

    Tripoli, N K; Cohen, K L; Proia, A D

    1992-01-01

    A major contributor to postkeratoplasty astigmatism may be donor/recipient disparity. Deficient or excess cornea at the wound is thought to influence the directions of the steep and flat meridians. Using an established model of penetrating keratoplasty in the cat, this study evaluated the morphometry of histopathologic wound features in the steep and flat meridians. Thirteen cats had successful penetrating keratoplasties after intentionally misshapen donor corneas were misaligned in misshapen recipient beds. At 9.50 +/- 0.32 (mean +/- 1 SEM) months after keratoplasty, photokeratography was performed and analyzed, corneas were sectioned along the steep and flat meridians, and four histologic sections were processed. Features of the wounds were measured using a Zeiss Videoplan. The relationships between the morphometry of each feature and every other feature, between the morphometry of each feature and eccentricity, and between the steep and flat section morphometry of each feature were statistically evaluated. Epithelial thickness, area of lamellar alteration, length of Descemet's membrane produced postoperatively, and the depth that preoperative Descemet's membrane was embedded in the stroma were correlated with eccentricity (corneal astigmatism). Stromal thickness and the presence or absence of folded and fragmented Descemet's membrane were not correlated with eccentricity. Wound morphometry at the steep meridians was neither correlated with nor significantly different from wound morphometry at the flat meridians. Differences between healing at the steep and flat meridians were not likely contributors to astigmatism. Disproportionate availability of tissue in wound regions may have affected healing throughout the entire wound over time. The absence of Bowman's layer in cats restricts application of our results to understanding the etiology of corneal astigmatism after penetrating keratoplasty in humans.

  6. Assessment and statistics of surgically induced astigmatism.

    Science.gov (United States)

    Naeser, Kristian

    2008-05-01

    The aim of the thesis was to develop methods for assessment of surgically induced astigmatism (SIA) in individual eyes, and in groups of eyes. The thesis is based on 12 peer-reviewed publications, published over a period of 16 years. In these publications older and contemporary literature was reviewed(1). A new method (the polar system) for analysis of SIA was developed. Multivariate statistical analysis of refractive data was described(2-4). Clinical validation studies were performed. The description of a cylinder surface with polar values and differential geometry was compared. The main results were: refractive data in the form of sphere, cylinder and axis may define an individual patient or data set, but are unsuited for mathematical and statistical analyses(1). The polar value system converts net astigmatisms to orthonormal components in dioptric space. A polar value is the difference in meridional power between two orthogonal meridians(5,6). Any pair of polar values, separated by an arch of 45 degrees, characterizes a net astigmatism completely(7). The two polar values represent the net curvital and net torsional power over the chosen meridian(8). The spherical component is described by the spherical equivalent power. Several clinical studies demonstrated the efficiency of multivariate statistical analysis of refractive data(4,9-11). Polar values and formal differential geometry describe astigmatic surfaces with similar concepts and mathematical functions(8). Other contemporary methods, such as Long's power matrix, Holladay's and Alpins' methods, Zernike(12) and Fourier analyses(8), are correlated to the polar value system. In conclusion, analysis of SIA should be performed with polar values or other contemporary component systems. The study was supported by Statens Sundhedsvidenskabeligt Forskningsråd, Cykelhandler P. Th. Rasmussen og Hustrus Mindelegat, Hotelejer Carl Larsen og Hustru Nicoline Larsens Mindelegat, Landsforeningen til Vaern om Synet

  7. Perioperative modulating factors on astigmatism in sutured cataract surgery.

    Science.gov (United States)

    Cho, Yang Kyeung; Kim, Man Soo

    2009-12-01

    To evaluate the factors that affect postoperative astigmatism and post-suture removal astigmatism, and to evaluate the risk factors associated with astigmatism axis shift. We performed a retrospective chart review of 130 eyes that had undergone uneventful phacoemulsification cataract surgery. Preoperative astigmatism was divided into four groups (Groups I, II, III, and IV) according to the differences between the axis of preoperative astigmatism (flattest axis) and the incision axis (105 degrees). We analyzed the magnitude and axis of the induced astigmatism after the operation and after suture removal in each group. We also analyzed the factors which affected the postoperative astigmatism and post-suture removal astigmatism in each sub-group of Groups I, II, III, and IV, excluding postoperative or post-suture removal axis shift (specifically, Group I(WAS), II(WAS), III(WAS), and IV(WAS)). We identified the variables associated with the prevalence of postoperative astigmatism axis shift and those associated with the prevalence of post-suture removal axis shift. An increase in the magnitude of postoperative astigmatism was associated with an increase in the preoperative magnitude of astigmatism in Groups I(WAS), II(WAS), and III(WAS) (pastigmatism was associated with an increase in the corneal tunnel length in Groups III(WAS) and IV(WAS) (psuture removal astigmatism was associated with an increase in the magnitude of postoperative astigmatism in Groups I(WAS) and IV(WAS) (psuture removal in Group IV(WAS) (psuture removal astigmatism was associated with late suture removal in Groups I(WAS) and II(WAS). A logistic regression analysis showed that the prevalence of post-suture removal astigmatism axis shift was associated with increased corneal tunnel length, decreased magnitude of postoperative astigmatism, and early suture removal. In order to reduce postoperative and post-suture removal astigmatism, we recommend a short corneal tunnel length and late suture removal

  8. [Clinical observation of astigmatism induced by corneal incision after phacoemulsification].

    Science.gov (United States)

    Xie, L; Zhu, G; Wang, X

    2001-03-01

    To evaluate the changes of astigmatism induced by corneal incision after phacoemulsification. Phacoemulsification was performed on 62 cases (78 eyes) without suture for a corneal incision. The changes of corneal astigmatism before and after operation in group A (incision at the superior nasal or superior temporal) and B (incision at the steepest corneal meridian) were compared. Three months after the operation, the surgical induced astigmatism was (0.83 plus minus 0.65) D and (0.72 plus minus 0.55) D in group A and B respectively. There was no significant difference, statistically (P > 0.05). The changes of corneal astigmatism were 0.11 D and 0.39 D in group A and B respectively, the difference being statistically significant (P astigmatism is very small after a corneal incision in phacoemulsification without a suture. If the incision is placed on the steepest meridian, the corneal astigmatism can be significantly reduced postoperatively.

  9. Treatment of corneal astigmatism with the new small-incision lenticule extraction (SMILE) laser technique: Is treatment of high degree astigmatism equally accurate, stable and safe as treatment of low degree astigmatism?

    DEFF Research Database (Denmark)

    Hansen, Rasmus Søgaard; Grauslund, Jakob; Lyhne, Niels

    98% of eyes with low astigmatism and 95% of eyes with high astigmatism (P=0.89) were within ±1.0 D. Stability: In total 38% of eyes with low astigmatism and 32% of eyes with high astigmatism (P=0.49) changed ≥0.5 D in refraction from one day to three months after surgery. Safety: Three eyes (0...... as treatment of low degree astigmatism. More eyes treated for high degree astigmatism lose two or more lines of BSCVA up to three months after surgery. Keywords Refractive surgery, astigmatism, SMILE...... for low or high degrees of astigmatism concerning accuracy, stability, and safety. Methods: Retrospective study of 1017 eyes treated with SMILE for myopia with low astigmatism or myopia with high astigmatism from 2011-2013 at the Department of Ophthalmology, Odense University Hospital, Denmark. Inclusion...

  10. Defocus and magnification dependent variation of TEM image astigmatism

    OpenAIRE

    Yan, Rui; Li, Kunpeng; Jiang, Wen

    2018-01-01

    Daily alignment of the microscope is a prerequisite to reaching optimal lens conditions for high resolution imaging in cryo-EM. In this study, we have investigated how image astigmatism varies with the imaging conditions (e.g. defocus, magnification). We have found that the large change of defocus/magnification between visual correction of astigmatism and subsequent data collection tasks, or during data collection, will inevitably result in undesirable astigmatism in the final images. The dep...

  11. Current Approaches for Management of Postpenetrating Keratoplasty Astigmatism

    OpenAIRE

    Sepehr Feizi; Mohammad Zare

    2011-01-01

    A successful corneal graft requires both clarity and an acceptable refraction. A clear corneal graft may be an optical failure if high astigmatism limits visual acuity. Intraoperative measures to reduce postkeratoplasty astigmatism include round and central trephination of cornea with an adequate size, appropriate sutures with evenly distributed tension, and perfect graft-host apposition. Suture manipulation has been described for minimising early postoperative astigmatism. If significant ast...

  12. [Analysis of postoperative astigmatism after phacoemulsification with intraocular lens implantation].

    Science.gov (United States)

    Zhang, Q; Sheng, Y; Li, Z

    2000-11-01

    To study the corneal astigmatism and the changes of surgically induced astigmatism after phacoemulsification with intraocular lens (IOL) implantation. Thirty-eight eyes of 38 patients treated with phacoemulsification through a superior inversed frown shaped scleral incision were examined by corneal topography and auto-ref-keratometer preoperatively, one day, one month and three months postoperatively. The postoperative corneal astigmatism at one day, one month and three months were (1.10 +/- 0.71), (1.08 +/- 0.66) and (0.87 +/- 0.55) D respectively. There was no statistic significance between the postoperative astigmatism at three months and at preoperative one day (P > 0.05). The mean surgically-induced astigmatism at postoperative one day, one month and three months were (1.37 +/- 1.03), (1.24 +/- 0.93) and (1.04 +/- 0.75) D respectively. There was significant difference between the astigmatism at three months and at one day postoperatively (P incision with no suture has little effect on corneal astigmatism. Vector analysis can systemically evaluate surgically induced astigmatism. The results of corneal topography are more reliable to reflect changes in corneal curvature than that of auto-ref-keratometer, and corneal topography has more important clinical value in evaluating surgically induced astigmatism.

  13. Computer simulation of arcuate keratotomy for astigmatism.

    Science.gov (United States)

    Hanna, K D; Jouve, F E; Waring, G O; Ciarlet, P G

    1992-01-01

    The development of refractive corneal surgery involves numerous attempts to isolate the effect of individual factors on surgical outcome. Computer simulation of refractive keratotomy allows the surgeon to alter variables of the technique and to isolate the effect of specific factors independent of other factors, something that cannot easily be done in any of the currently available experimental models. We used the finite element numerical method to construct a mathematical model of the eye. The model analyzed stress-strain relationships in the normal corneoscleral shell and after astigmatic surgery. The model made the following assumptions: an axisymmetric eye, an idealized aspheric anterior corneal surface, transversal isotropy of the cornea, nonlinear strain tensor for large displacements, and near incompressibility of the corneoscleral shell. The eye was assumed to be fixed at the level of the optic nerve. The model described the acute elastic response of the eye to corneal surgery. We analyzed the effect of paired transverse arcuate corneal incisions for the correction of astigmatism. We evaluated the following incision variables and their effect on change in curvature of the incised and unincised meridians: length (longer, more steepening of unincised meridian), distance from the center of the cornea (farther, less flattening of incised meridian), depth (deeper, more effect), and the initial amount of astigmatism (small effect). Our finite element computer model gives reasonably accurate information about the relative effects of different surgical variables, and demonstrates the feasibility of using nonlinear, anisotropic assumptions in the construction of such a computer model. Comparison of these computer-generated results to clinically achieved results may help refine the computer model.

  14. Characteristics of astigmatism in Black South African high school ...

    African Journals Online (AJOL)

    Background: Astigmatism impairs vision at various distances and causes symptoms of asthenopia which negatively impacts reading efficiency. Objective: The aim of conducting this study was to determine the prevalence and distribution of astigmatism and its relationship to gender, age, school grade levels and spherical ...

  15. Experimental circular keratotomy for correction of corneal astigmatism

    NARCIS (Netherlands)

    Wijdh, RH; van Rij, G

    1998-01-01

    PURPOSE: To investigate the effect of circular keratotomy depth and diameter on corneal astigmatism. METHODS: High astigmatism was induced in 25 human donor eyes by an anterior radial 7-0 silk suture across the corneoscleral limbus. With a 6.0, 6.5, 7.0, or 7.5 mm trephine, a 0.3 mm deep circular

  16. Current Approaches for Management of Postpenetrating Keratoplasty Astigmatism

    Directory of Open Access Journals (Sweden)

    Sepehr Feizi

    2011-01-01

    Full Text Available A successful corneal graft requires both clarity and an acceptable refraction. A clear corneal graft may be an optical failure if high astigmatism limits visual acuity. Intraoperative measures to reduce postkeratoplasty astigmatism include round and central trephination of cornea with an adequate size, appropriate sutures with evenly distributed tension, and perfect graft-host apposition. Suture manipulation has been described for minimising early postoperative astigmatism. If significant astigmatism remains after suture removal, which cannot be corrected by optical means, then further surgical procedures containing relaxing incisions, compression sutures, laser refractive surgery, insertion of intrastromal corneal ring segments, wedge resection, and toric intraocular lens implantation can be performed. When astigmatism cannot be reduced using one or more abovementioned approaches, repeat penetrating keratoplasty should inevitably be considered. However, none of these techniques has emerged as an ideal one, and corneal surgeons may require combining two or more approaches to exploit the maximum advantages.

  17. Current Approaches for Management of Postpenetrating Keratoplasty Astigmatism

    Science.gov (United States)

    Feizi, Sepehr; Zare, Mohammad

    2011-01-01

    A successful corneal graft requires both clarity and an acceptable refraction. A clear corneal graft may be an optical failure if high astigmatism limits visual acuity. Intraoperative measures to reduce postkeratoplasty astigmatism include round and central trephination of cornea with an adequate size, appropriate sutures with evenly distributed tension, and perfect graft-host apposition. Suture manipulation has been described for minimising early postoperative astigmatism. If significant astigmatism remains after suture removal, which cannot be corrected by optical means, then further surgical procedures containing relaxing incisions, compression sutures, laser refractive surgery, insertion of intrastromal corneal ring segments, wedge resection, and toric intraocular lens implantation can be performed. When astigmatism cannot be reduced using one or more abovementioned approaches, repeat penetrating keratoplasty should inevitably be considered. However, none of these techniques has emerged as an ideal one, and corneal surgeons may require combining two or more approaches to exploit the maximum advantages. PMID:21811668

  18. Astigmatic changes following pterygium removal: Comparison of 5 different methods

    Directory of Open Access Journals (Sweden)

    Rana Altan-Yaycioglu

    2013-01-01

    Full Text Available Aims: To investigate the effect of surgery type on the postoperative astigmatism in pterygium surgery. Settings and Design: Retrospective comparative clinical trial. Materials and Methods: Data of 240 eyes that underwent pterygium excision were investigated. Following removal of the pterygium, patients underwent 5 different types of surgeries: Conjunctival autograft with sutures (CAG-s or fibrin glue (CAG-g, conjunctival rotational flap (CRF, or amniotic membrane transplantation with either suture (AMT-s or with glue (AMT-g. The preoperative and postoperative keratometric measurements, evaluated using an automated keratorefractometer, were noted. Statistical Analysis: The overall changes in BCVA and astigmatic degree were evaluated using Wilcoxon signed rank test. The difference in astigmatic values between groups was calculated using one way analysis of variance (ANOVA. Results: The most commonly performed procedure was CAG-s (N = 115, followed by CAG-g (N = 53, CRF (N = 47, AMT-s (N = 15, and AMT-g (N = 10. Following surgery, astigmatic values decreased from 3.47 ± 2.50 D to 1.29 ± 1.07 D (P < 0.001, paired t test. The changes in astigmatism was significantly related to the preoperative size of the pterygium (ρ = 3.464, P = 0.005. The postoperative astigmatism correlated with preoperative astigmatism (ρ = 0.351, P < 0.001, Spearman correlation analysis. The changes in astigmatic values was not related to the method of surgery (P = 0.055, ANOVA. Conclusion: Pterygium results in high corneal astigmatism, which decreases to an acceptable level following excision. According to our study, the type of grafting as CAG, CRF or AMT or the use of suture or glue to fixate the graft does not have a significant effect on the change in astigmatism degree.

  19. Impact of cylinder axis on the treatment for astigmatic amblyopia.

    Science.gov (United States)

    Chou, Yen-Shou; Tai, Ming-Cheng; Chen, Po-Liang; Lu, Da-Wen; Chien, Ke-Hung

    2014-04-01

    To compare the effects of oblique astigmatism on refractive amblyopia in children aged 3-7 years with those having orthogonal astigmatism. A retrospective review of medical records. The medical records of patients attending Tri-Service General Hospital in Taiwan from January 2003 to December 2010 were reviewed and summarized. Seventy-two children with oblique astigmatism-related refractive amblyopia (Group 1) and 82 children with orthogonal astigmatism (Group 2) were chosen. Characteristics such as baseline visual acuity (VA), the time course of VA improvement, refractive error, and family history were assessed. Group 1 showed a worse baseline mean VA (±SD) of 0.61 (0.13) vs 0.52 (0.16) logMAR (P = .01), a slower rate of amblyopia improvement, and higher prevalence of parental oblique astigmatism (29% vs 5.5%; P amblyopia in Group 1 of 2.48 (0.82) was lower than that in Group 2: 2.93 (0.71) (P = .006). However, Group 1 achieved a noninferior resolution of amblyopia (mean final VA 0.18 vs 0.16 logMAR) after longer treatment of 6.45 (2.44) vs 5.86 (2.92) months (P = .039). A smaller degree of initial oblique astigmatism caused amblyopia than did orthogonal astigmatism. Although the children with oblique astigmatism achieved equal resolution rates after treatment, this took longer. Therefore, we should pay more attention to children with mild oblique astigmatism, as they are more likely to develop oblique astigmatism-related amblyopia. Moreover, early diagnosis and prompt treatment might help visual improvement. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Simulated astigmatism impairs academic-related performance in children.

    Science.gov (United States)

    Narayanasamy, Sumithira; Vincent, Stephen J; Sampson, Geoff P; Wood, Joanne M

    2015-01-01

    Astigmatism is an important refractive condition in children. However, the functional impact of uncorrected astigmatism in this population is not well established, particularly with regard to academic performance. This study investigated the impact of simulated bilateral astigmatism on academic-related tasks before and after sustained near work in children. Twenty visually normal children (mean age: 10.8 ± 0.7 years; six males and 14 females) completed a range of standardised academic-related tests with and without 1.50 D of simulated bilateral astigmatism (with both academic-related tests and the visual condition administered in a randomised order). The simulated astigmatism was induced using a positive cylindrical lens while maintaining a plano spherical equivalent. Performance was assessed before and after 20 min of sustained near work, during two separate testing sessions. Academic-related measures included a standardised reading test (the Neale Analysis of Reading Ability), visual information processing tests (Coding and Symbol Search subtests from the Wechsler Intelligence Scale for Children) and a reading-related eye movement test (the Developmental Eye Movement test). Each participant was systematically assigned either with-the-rule (WTR, axis 180°) or against-the-rule (ATR, axis 90°) simulated astigmatism to evaluate the influence of axis orientation on any decrements in performance. Reading, visual information processing and reading-related eye movement performance were all significantly impaired by both simulated bilateral astigmatism (p  0.05). Simulated astigmatism led to a reduction of between 5% and 12% in performance across the academic-related outcome measures, but there was no significant effect of the axis (WTR or ATR) of astigmatism (p > 0.05). Simulated bilateral astigmatism impaired children's performance on a range of academic-related outcome measures irrespective of the orientation of the astigmatism. These findings have

  1. Defocus and magnification dependent variation of TEM image astigmatism.

    Science.gov (United States)

    Yan, Rui; Li, Kunpeng; Jiang, Wen

    2018-01-10

    Daily alignment of the microscope is a prerequisite to reaching optimal lens conditions for high resolution imaging in cryo-EM. In this study, we have investigated how image astigmatism varies with the imaging conditions (e.g. defocus, magnification). We have found that the large change of defocus/magnification between visual correction of astigmatism and subsequent data collection tasks, or during data collection, will inevitably result in undesirable astigmatism in the final images. The dependence of astigmatism on the imaging conditions varies significantly from time to time, so that it cannot be reliably compensated by pre-calibration of the microscope. Based on these findings, we recommend that the same magnification and the median defocus of the intended defocus range for final data collection are used in the objective lens astigmatism correction task during microscope alignment and in the focus mode of the iterative low-dose imaging. It is also desirable to develop a fast, accurate method that can perform dynamic correction of the astigmatism for different intended defocuses during automated imaging. Our findings also suggest that the slope of astigmatism changes caused by varying defocuses can be used as a convenient measurement of objective lens rotation symmetry and potentially an acceptance test of new electron microscopes.

  2. Influence of different types of astigmatism on visual acuity.

    Science.gov (United States)

    Remón, Laura; Monsoriu, Juan A; Furlan, Walter D

    To investigate the change in visual acuity (VA) produced by different types of astigmatism (on the basis of the refractive power and position of the principal meridians) on normal accommodating eyes. The lens induced method was employed to simulate a set of 28 astigmatic blur conditions on different healthy emmetropic eyes. Additionally, 24 values of spherical defocus were also simulated on the same eyes for comparison. VA was measured in each case and the results, expressed in logMAR units, were represented against of the modulus of the dioptric power vector (blur strength). LogMAR VA varies in a linear fashion with increasing astigmatic blur, being the slope of the line dependent on the accommodative demand in each type of astigmatism. However, in each case, we found no statistically significant differences between the three axes investigated (0°, 45°, 90°). Non-statistically significant differences were found either for the VA achieved with spherical myopic defocus (MD) and mixed astigmatism (MA). VA with simple hyperopic astigmatism (SHA) was higher than with simple myopic astigmatism (SMA), however, in this case non conclusive results were obtained in terms of statistical significance. The VA achieved with imposed compound hyperopic astigmatism (CHA) was highly influenced by the eye's accommodative response. VA is correlated with the blur strength in a different way for each type of astigmatism, depending on the accommodative demand. VA is better when one of the focal lines lie on the retina irrespective of the axis orientation; accommodation favors this situation. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

  3. LASIK for post penetrating keratoplasty astigmatism and myopia

    Science.gov (United States)

    Webber, S.; Lawless, M.; Sutton, G.; Rogers, C.

    1999-01-01

    AIMS—To report the results of a series of patients who were treated with LASIK to correct post penetrating keratoplasty ametropia.
METHODS—26 eyes of 24 patients underwent LASIK to correct astigmatism and myopia after corneal transplantation; 14 eyes also received arcuate cuts in the stromal bed at the time of surgery. The mean preoperative spherical equivalent was −5.20D and the mean preoperative astigmatism was 8.67D.
RESULTS—The results of 25 eyes are reported. The mean 1 month values for spherical equivalent and astigmatism were −0.24D and 2.48D respectively. 18 eyes have been followed up for 6 months or more. The final follow up results for these eyes are −1.91D and 2.92D for spherical equivalent and astigmatism. The patients undergoing arcuate cuts were less myopic but had greater astigmatism than those not. The patients receiving arcuate cuts had a greater target induced astigmatism, surgically induced astigmatism, and astigmatism correction index than those eyes that did not. One eye suffered a surgical complication. No eyes lost more than one line of BSCVA and all eyes gained between 0 and 6 lines UCVA.
CONCLUSIONS—LASIK after penetrating keratoplasty is a relatively safe and effective procedure. It reduces both the spherical error and the cylindrical component of the ametropia. Correction of high astigmatism may be augmented by performing arcuate cuts in the stromal bed.

 PMID:10460767

  4. Comparability and repeatability of different methods of corneal astigmatism assessment

    Directory of Open Access Journals (Sweden)

    Ferreira TB

    2017-12-01

    Full Text Available Tiago B Ferreira, Filomena J Ribeiro Department of Ophthalmology, Hospital da Luz, Lisbon, Portugal Purpose: To assess the comparability and repeatability of keratometric and astigmatism values measured by four techniques: Orbscan IIz® (Bausch and Lomb, Lenstar LS 900® (Haag-Streit, Cassini® (i-Optics, and Total Cassini (anterior + posterior surface, in healthy volunteers.Patients and methods: Fifteen healthy volunteers (30 eyes were assessed by the four techniques. In each eye, three consecutive measures were performed by the same operator. Keratometric and astigmatism values were recorded. The intraclass correlation coefficient (ICC was used to assess comparability and repeatability. Agreement between measurement techniques was evaluated with Bland–Altman plots.Results: Comparability was high between all measurement techniques for minimum keratometry (K1, maximum keratometry (K2, astigmatism magnitude, and astigmatism axis, with ICC >0.900, except for astigmatism magnitude measured by Cassini compared to Lenstar (ICC =0.798 and Orbscan compared to Lenstar (ICC =0.810. However, there were some differences in the median values of K1 and K2 between measurement techniques, and the Bland–Altman plots showed a wide data spread for all variables, except for astigmatism magnitude measured by Cassini and Total Cassini. For J0 and J45, comparability was only high for J0 between Cassini and Orbscan. Repeatability was also high for all measurement techniques except for K2 (ICC =0.814 and J45 (ICC =0.621 measured by Cassini.Conclusion: All measurement techniques showed high comparability regarding K1, K2, and astigmatism axis. Although posterior corneal surface is known to influence these measurements, comparability was high between Cassini and Total Cassini regarding astigmatism magnitude and axis. However, the wide data spread suggests that none of these devices should be used interchangeably. Keywords: astigmatism, keratometry, topography

  5. Interferometric measurement of actual oblique astigmatism of ophthalmic lenses

    Science.gov (United States)

    Wihardjo, Erning

    1995-03-01

    A technique for measuring oblique astigmatism error of ophthalmic lenses is described. The technique is based on a Mach-Zehnder interferometer, which allows us to simulate the actual conditions of the eye. The effects of the lens power, the pupilary aperture size and the viewing distance in calculating a projected pupil zone on the lens are discussed. The projected pupil size on the lens affects the measurement result of the oblique astigmatism error. Conversion of the interferogram to astigmatism error in diopters is given.

  6. The effects of lateral head tilt on ocular astigmatic axis

    Directory of Open Access Journals (Sweden)

    Hamid Fesharaki

    2014-01-01

    Conclusion: Any minimal angle of head tilt may cause erroneous measurement of astigmatic axis and should be avoided during refraction. One cannot rely on the compensatory function of ocular counter-torsion during the refraction.

  7. [Corneal astigmatism after tunnel incision for cataract extraction].

    Science.gov (United States)

    Skubiszewska, T; Mrzygłód, S; Warczyński, A; Krzysztofik, R

    1996-01-01

    To evaluate the development of astigmatism after cataract extraction depending on the kind of incision Astigmatism was examined in 107 eyes of 92 patients, who underwent cataract extraction, mostly with IOL's implantation. In 52 eyes phacoemulsification with tunnel incision, measuring 5 mm in 27 and 8 mm in 25, was performed. In the control group of 55 eyes incision with scleral flap measured 2/5 of the corneal circumference. In cases with 5 mm incisions no sutures were used, in 8 mm incisions wounds were closed with single sutures and in control group the double continuous sutures were applied. Astigmatism was measured in two days, one week, four weeks and 3 months after surgery. Post-operative astigmatism decreased gradually and after 3 months was average 0.14 D in the eyes without sutures, 0.68 D in those with single ones and 1.78 D in the control group.

  8. Patterned corneal collagen crosslinking for astigmatism: computational modeling study.

    Science.gov (United States)

    Seven, Ibrahim; Sinha Roy, Abhijit; Dupps, William J

    2014-06-01

    To test the hypothesis that spatially selective corneal stromal stiffening can alter corneal astigmatism and assess the effects of treatment orientation, pattern, and material model complexity in computational models using patient-specific geometries. Cornea and Refractive Surgery Service, Academic Eye Institute, Cleveland, Ohio, USA. Computational modeling study. Three-dimensional corneal geometries from 10 patients with corneal astigmatism were exported from a clinical tomography system (Pentacam). Corneoscleral finite element models of each eye were generated. Four candidate treatment patterns were simulated, and the effects of treatment orientation and magnitude of stiffening on anterior curvature and aberrations were studied. The effect of material model complexity on simulated outcomes was also assessed. Pretreatment anterior corneal astigmatism ranged from 1.22 to 3.92 diopters (D) in a series that included regular and irregular astigmatic patterns. All simulated treatment patterns oriented on the flat axis resulted in mean reductions in corneal astigmatism and depended on the pattern geometry. The linear bow-tie pattern produced a greater mean reduction in astigmatism (1.08 D ± 0.13 [SD]; range 0.74 to 1.23 D) than other patterns tested under an assumed 2-times increase in corneal stiffness, and it had a nonlinear relationship to the degree of stiffening. The mean astigmatic effect did not change significantly with a fiber- or depth-dependent model, but it did affect the coupling ratio. In silico simulations based on patient-specific geometries suggest that clinically significant reductions in astigmatism are possible with patterned collagen crosslinking. Effect magnitude was dependent on patient-specific geometry, effective stiffening pattern, and treatment orientation. Proprietary or commercial disclosures are listed after the references. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  9. Comparability and repeatability of different methods of corneal astigmatism assessment.

    Science.gov (United States)

    Ferreira, Tiago B; Ribeiro, Filomena J

    2018-01-01

    To assess the comparability and repeatability of keratometric and astigmatism values measured by four techniques: Orbscan IIz ® (Bausch and Lomb), Lenstar LS 900 ® (Haag-Streit), Cassini ® (i-Optics), and Total Cassini (anterior + posterior surface), in healthy volunteers. Fifteen healthy volunteers (30 eyes) were assessed by the four techniques. In each eye, three consecutive measures were performed by the same operator. Keratometric and astigmatism values were recorded. The intraclass correlation coefficient (ICC) was used to assess comparability and repeatability. Agreement between measurement techniques was evaluated with Bland-Altman plots. Comparability was high between all measurement techniques for minimum keratometry (K1), maximum keratometry (K2), astigmatism magnitude, and astigmatism axis, with ICC >0.900, except for astigmatism magnitude measured by Cassini compared to Lenstar (ICC =0.798) and Orbscan compared to Lenstar (ICC =0.810). However, there were some differences in the median values of K1 and K2 between measurement techniques, and the Bland-Altman plots showed a wide data spread for all variables, except for astigmatism magnitude measured by Cassini and Total Cassini. For J0 and J45, comparability was only high for J0 between Cassini and Orbscan. Repeatability was also high for all measurement techniques except for K2 (ICC =0.814) and J45 (ICC =0.621) measured by Cassini. All measurement techniques showed high comparability regarding K1, K2, and astigmatism axis. Although posterior corneal surface is known to influence these measurements, comparability was high between Cassini and Total Cassini regarding astigmatism magnitude and axis. However, the wide data spread suggests that none of these devices should be used interchangeably.

  10. Effects of wound architecture and suture technique on postoperative astigmatism.

    Science.gov (United States)

    Gimbel, H V; Sun, R; DeBroff, B M

    1995-01-01

    A prospective randomized investigation was performed to evaluate the effects of wound architecture and suture techniques on postoperative astigmatism after phacoemulsification and intraocular lens implantation. Two hundred eyes with preexisting with-the-rule astigmatism were randomized into four groups: (1) sutureless scleral tunnel frown incision, (2) scleral tunnel frown incision with a horizontal suture, (3) scleral tunnel frown incision with both a horizontal and a running suture, and (4) posterior limbal acute beveled cataract incision with a running suture. All the incisions were placed in the vertical steep meridian. Data were analyzed from 128 cases with 1-year follow-up. The results revealed that at the 2-month postoperative visit, preexisting astigmatism was significantly reduced in group 1 (P = .029) and significantly increased in groups 3 (P = .020) and 4 (P = .005). There was no significant change in group 2 (P = .06). By the 1-year postoperative visit, there was no significant difference in astigmatism from preoperative levels for all four groups. Vector analysis revealed no significant difference in the mean surgically induced cylinder at 1 year in all four groups. The number of eyes with induced against-the-rule astigmatism, however, was significantly higher than the number of eyes with induced with-the-rule astigmatism in all four groups (P sutured wounds placed in the vertical steep meridian may initially increase with-the-rule astigmatism, whereas nonsutured wounds placed in the vertical steep meridian may initially reduce with-the-rule astigmatism. By 1 year, however, a mean flattening of the vertical steep meridian was observed in the three groups with sutures as well as in the group without sutures.

  11. Treatment of corneal astigmatism with the new small-incision lenticule extraction (SMILE) laser technique: Is treatment of high degree astigmatism equally accurate, stable and safe as treatment of low degree astigmatism?

    DEFF Research Database (Denmark)

    Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob

    for low or high degrees of astigmatism concerning accuracy, stability, and safety. Methods: Retrospective study of 1017 eyes treated with SMILE for myopia with low astigmatism or myopia with high astigmatism from 2011-2013 at the Department of Ophthalmology, Odense University Hospital, Denmark. Inclusion...... criteria were: Best spectacle-corrected visual acuity (BSCVA) of 20/25 or better on Snellen chart, and no other ocular condition than myopia with or without astigmatism. Results: In total 660 eyes completed the 3 months follow-up examination, in which 536 eyes had pre-operatively low astigmatism (mean...... astigmatism -0.59±0.52 D, range: 0.00 to -1.75) and 124 eyes had pre-operatively high astigmatism (mean astigmatism -3.09±0.77 D, range: -2.00 to -5.75). Accuracy: 88% of eyes with low astigmatism and 65% of eyes with high astigmatism (P=0.06) were within ±0.5 D of attempted post-operative astigmatism, whilst...

  12. Epidemiological survey of astigmatism among 926 preschool children in a kindergarten in Enshi City

    Directory of Open Access Journals (Sweden)

    Mao-Ju Zhang

    2017-09-01

    Full Text Available AIM: To study the type, degree and axial distribution of low vision astigmatism in preschool children. METHODS: A group of 3-6 years old children were selected for astigmatism screening, and statistical analysis was performed on the detected 445 eyes of 308 people. RESULTS: With more than 0.50D astigmatism criteria, astigmatism examination of 308 people, accounting for 36.2%, of which 137 eyes astigmatism, astigmatism 171 monocular. The five types of astigmatism were compound hyperopia 40.7%, mixed 35.5%, compound myopia 8.5%, myopia 8.3%, simple hyperopia astigmatism degree 7.0%; 69.0% were mild, 16.6% moderate, 14.4% severe. Astigmatism axial distribution was with the rule for 54.9%, against the rule 28.8%, oblique 16.6%. In binocular astigmatism eyes, axial symmetry was in 35.8%, asymmetry in 64.2%. CONCLUSION: The main type of astigmatism in preschool children are compound hyperopia and mixed astigmatism. Astigmatism degree is mainly mild. With the increase of age, the detection rate of moderate and high astigmatism increased.

  13. Artisan toric lens implantation for correction of postkeratoplasty astigmatism.

    Science.gov (United States)

    Nuijts, Rudy M M A; Abhilakh Missier, Kiran A; Nabar, Vaisjali A; Japing, Wouter J

    2004-06-01

    To determine the efficacy of Artisan toric iris-fixated lens implantation after penetrating keratoplasty to correct high ametropia and astigmatism. Prospective, noncomparative case series. Artisan toric lens implantation was performed in 16 eyes of 16 patients who were contact lens intolerant or were unable to wear glasses because of anisometropia, high astigmatism, or both. Sixteen eyes of 16 patients received Artisan toric lenses for postkeratoplasty astigmatism, anisometropia, or both. Manifest refraction, uncorrected and spectacle-corrected visual acuity, and corneal topography were performed before surgery and 1, 3, 6, 12, and 18 months after surgery. Efficacy, percent reduction of refractive astigmatism, topographical astigmatism, anisometropia of defocus, and the astigmatism correction index were determined. A patient satisfaction questionnaire and specular microscopy results were assessed. The mean +/- standard deviation of the preoperative refractive cylinder was -6.66+/-1.93 diopters (D; range, -4.0 to -10.0 D), which was reduced to -2.08+/-1.33 D, -2.14+/-1.76 D, -1.98+/-1.65 D, -1.84+/-0.77 D, and -1.42+/-0.78 D at 1 month, 3 months, 6 months, 12 months, and the final follow-up examination (8.4+/-4.9 months), respectively. Spherical equivalent was reduced from -4.90+/-5.50 D before surgery to -0.96+/-0.86 D at the final follow-up. The uncorrected and best-corrected visual acuities were >/=20/40 in 42% and 100% of eyes, respectively. There was no loss of best-corrected visual acuity and a gain of at least 2 lines in 50% of eyes. The percent reduction in refractive astigmatism, topographical astigmatism, and anisometropia of defocus were 78.0+/-11.5%, 20.3+/-34.9%, and 77.0+/-12.0%, respectively. The astigmatism correction index was 102.8+/-18.6%. Satisfaction increased from 3.2 to 8.3 after implantation. The endothelial cell loss was 7.6+/-18.9% at 3 months and 16.6+/-20.4% at the last follow-up. In 1 patient, a reversible graft rejection occurred

  14. Astigmatism induced by conventional spherical ablation after PRK and LASIK in myopia with astigmatism < 1.00 D

    Directory of Open Access Journals (Sweden)

    Christiansen SM

    2012-12-01

    Full Text Available Steven M Christiansen,1 Mark D Mifflin,1 Jason N Edmonds,1 Rachel G Simpson,2 Majid Moshirfar11John A Moran Eye Center, University of Utah, Salt Lake City, UT, 2The University of Arizona College of Medicine, Phoenix, AZ, USABackground: The purpose of this study was to evaluate surgically-induced astigmatism after spherical ablation in photorefractive keratectomy (PRK and laser-assisted in situ keratomileusis (LASIK for myopia with astigmatism < 1.00 D.Methods: The charts of patients undergoing spherical PRK or LASIK for the correction of myopia with minimal astigmatism of <1.00 D from 2002 to 2012 at the John A Moran Eye Center in Salt Lake City, UT, were retrospectively reviewed. Astigmatism was measured by manifest refraction. The final astigmatic refractive outcome at 6 months postoperatively was compared with the initial refraction by Alpins vector analysis.Results: For PRK, average cylinder increased from 0.39 ± 0.25 (0.00–0.75 preoperatively to 0.55 ± 0.48 (0.00–1.75 postoperatively (P = 0.014, compared with an increase in LASIK eyes from 0.40 ± 0.27 (0.00–0.75 preoperatively to 0.52 ± 0.45 (0.00–2.00 postoperatively (P = 0.041. PRK eyes experienced an absolute value change in cylinder of 0.41 ± 0.32 (0.00–1.50 and LASIK eyes experienced a change of 0.41 ± 0.31 (0.00–1.50, P = 0.955. Mean surgically-induced astigmatism was 0.59 ± 0.35 (0.00–1.70 in PRK eyes, with an increase in surgically-induced astigmatism of 0.44 D for each additional 1.00 D of preoperative cylinder; in LASIK eyes, mean surgically-induced astigmatism was 0.55 ± 0.32 (0.00–1.80, P = 0.482, with an increase in surgically-induced astigmatism of 0.29 D for each 1.00 D of preoperative cylinder.Conclusion: Spherical ablation can induce substantial astigmatism even in eyes with less than one diopter of preoperative astigmatism in both PRK and LASIK. No significant difference in the magnitude of surgically-induced astigmatism was found between eyes

  15. Late onset post-keratoplasty astigmatism in patients with keratoconus

    Science.gov (United States)

    Lim, L; Pesudovs, K; Goggin, M; Coster, D J

    2004-01-01

    Aim: 10 eyes of 10 patients are reported where progression of keratoconus in the host cornea occurred more than 10 years after penetrating keratoplasty with resultant increase in astigmatism. The technique and results of graft refractive surgery in seven eyes are presented. Methods: The clinical features and management of these patients were retrospectively analysed. Graft refractive surgery involved an incision at the graft-host junction adjacent to the host thinning with compressive resuturing. Astigmatic changes were calculated using vector analysis. Results: There were seven men and three women with a mean age of 41.2 years. The average age when undergoing penetrating keratoplasty in the affected eye was 28.4 years and the average time after penetrating keratoplasty until keratoconus appeared in the host cornea defined by host thinning was 13.5 years. The mean cylinder power before host thinning was noted was 5.07D (SD 2.19) and the mean after host thinning was 11.0D (2.53). The mean vector calculated disease induced astigmatism magnitude was 7.59D (3.09). Graft refractive surgery was performed in seven eyes. The mean cylinder power before and after graft refractive surgery was 11.28D (2.15) and 7.09D (5.53) respectively. The surgically induced astigmatism vector magnitude was 7.36D (4.88). Conclusion: Progression of keratoconus in the host cornea late after penetrating keratoplasty is characterised by a large astigmatic change where the flat axis of astigmatism passes through an area of host thinning visible on slit lamp examination. Compressive resuturing performed in the area of host thinning resulted in satisfactory reduction of astigmatism. PMID:14977772

  16. Three Methods for Correction of Astigmatism during Phacoemulsification

    Science.gov (United States)

    Mohammad-Rabei, Hossein; Mohammad-Rabei, Elham; Espandar, Goldis; Javadi, Mohammad Ali; Jafarinasab, Mohammad Reza; Hashemian, Seyed Javad; Feizi, Sepehr

    2016-01-01

    Purpose: To compare the safety and efficacy of three methods for correcting pre-existing astigmatism during phacoemulsification. Methods: This prospective, comparative, non-randomized study was conducted from March 2010 to January 2011, and included patients with keratometric astigmatism ≥1.25 D undergoing cataract surgery. Astigmatism was corrected using the following approaches: limbal relaxing incisions (LRI) on the steep meridian, extension and suturing of the phaco incision created at the steep meridian (extended-on-axis incision, EOAI), and toric intraocular lens (tIOL) implantation. Keratometric and refractive astigmatism were evaluated 1, 8, and 24 weeks postoperatively. Results: Eighty-three eyes of 72 patients (35 male and 37 female) with mean age of 62.4 ± 14.3 (range, 41-86) years were enrolled. The astigmatism was corrected by using the LRI, EOAI and tIOL implantation methods in 17, 33 and 33 eyes, respectively. Postoperative uncorrected distance visual acuity (UDVA) was significantly improved in all three groups. The difference in postoperative UDVA was not statistically significant among the study groups throughout follow-up except at week 24, when UCVA was significantly better in the tIOL group as compared to the EOAI group (P = 0.024). There is no statistically significant difference of correction index and index of success between three groups at week 24 (P = 0.085 and P = 0.085 respectively). Conclusion: There was no significant difference in astigmatism reduction among the three methods of astigmatism correction during phacoemulsification. Each of these methods can be used at the discretion of the surgeon. PMID:27413496

  17. Small Incision Lenticule Extraction for Postkeratoplasty Myopia and Astigmatism

    Directory of Open Access Journals (Sweden)

    Tamer H. Massoud

    2016-01-01

    Full Text Available Purpose. To evaluate the visual and refractive outcomes after small incision lenticule extraction (SMILE for treating myopia and myopic astigmatism after penetrating keratoplasty (PKP. Design. Case-series. Methods. Ten eyes of 10 patients with previous PKP and residual myopic astigmatism for whom pentacam imaging and thickness measurements were acceptable for laser vision correction. Manifest refraction (MR, uncorrected distance visual acuity (UDVA, and corrected distance visual acuity (CDVA were obtained preoperatively and one day, one week, and one, 3, and 6 months postoperatively. Cases were operated on the VisuMax® femtosecond laser platform with 500 kHz repetition rate. Results. The mean correction ratio for spherical errors was 0.84±0.19 D and for the mean refractive spherical equivalent (MRSE was 0.79±0.13 D. Vector analysis showed a mean astigmatism reduction at the intended axis of 67±25.25%, a correction index of 0.81±0.21, and an overall mean percentage of success of astigmatism surgery of 53±37.9%. The postoperative MRSE was stable throughout the 6-month follow-up period. The efficacy index was 0.93 and the safety index was 1.12. Conclusion. SMILE for correction of post-PKP myopia and astigmatism is effective, safe, and stable with moderate accuracy and predictability. Centration of the treatment within the grafts was easily performed.

  18. Relaxing incisions with compression sutures to reduce astigmatism after epikeratoplasty.

    Science.gov (United States)

    Fronterre, A; Portesani, G P

    1990-01-01

    Relaxing incisions with compression sutures were performed in seven eyes with high astigmatism following epikeratoplasty for keratoconus and in one case of posttraumatic aphakia. Mean preoperative keratometric astigmatism was 7.64 +/- 2.51 diopters (range 5.50 D to 13.00 D) in the epikeratoplasties for keratoconus and about 10.00 D in the hyperopic epikeratoplasty. The surgical procedure consisted of a free-hand dissection perpendicular to the steeper meridian along the scar between the edge of the epikeratoplasty lenticule and the recipient cornea, with an additional incision into the recipient stroma to an approximate depth of 80%. Following the incisions, compression sutures were added 90 degrees away in the flatter meridian. After surgery, the net decrease in keratometric astigmatism was 6.50 D +/- 2.90 D (range 5.00 to 13.00 D) in the eyes with epikeratoplasty for keratoconus and 6.50 D in the eye with hyperopic epikeratoplasty. Uncorrected visual acuity improved in six eyes and remained unchanged in two eyes. Spectacle-corrected visual acuity improved in every eye and contact-lens-corrected visual acuity improved in seven eyes and was unchanged in one eye. This procedure, already employed for astigmatism correction after penetrating keratoplasty, was effective in decreasing astigmatism after epikeratoplasty.

  19. [The application of vector analysis for evaluation of astigmatism correction in the corneal refractive surgery].

    Science.gov (United States)

    Zhang, Jiamei; Wang, Yan

    2016-01-01

    Since sixty percent of ametropes obtain astigmatism, which has influence on the visual quality, correcting the astigmatism is always the focus of concerns during visual correction procedures especially for the corneal refractive surgery. The postoperative spherical equivalent or residual cylindrical dioptors was used as quantitative index to evaluate the correction of astigmatism previously; however, such results neglect the effect of astigmatic axis shift on the treatment. Taking astigmatism as a vector parameter could describe the magnitude and direction of astigmatism accurately, thus it was increasingly applied in the evaluation of astigmatism correction. This paper reviews the present vector analysis methods, evaluation indexes and its application for the correction of astigmatism in the corneal refractive surgery.

  20. EFFECT OF ARCUATE INCISION ON POST-KERATOPLASTY ASTIGMATISM

    Directory of Open Access Journals (Sweden)

    Mehdi Hosseini Tehrani

    1995-07-01

    Full Text Available This work is a report 0/9 cases ofarcuate incision for correction 0/astigmatism, after penetrating keratoplasty. Plannings were based OJJ corneal topography, and the first operation was always arcuate incision alone. 11,e secondary plans were based on refractive errors. The mean of preoperative astigmatism was 6D with the range of5 to 9/. After arcuate incision a/the graft-host interface in the firs' operation, 'he mean reduction ofastigmatism was 3. OS/ with the range 0[0.5- 4.5]. Mean spherical equivalent change was O.16D. Arcuate incision is an appropriate methodfor correction ofastigmatism after PK and can he considered a.s a single procedure for [ow astigmatism, although the results may be unprediaable:

  1. Astigmatism induced by intrastromal corneal suture after small incision phacoemulsification.

    Science.gov (United States)

    Chipont-Benabent, E; Artola Roig, A; Pérez-Santonja, J J; Guisbert Medel, M; Alió Sanz, J L

    1998-04-01

    To evaluate the course of astigmatic evolution and complications after clear corneal incisions using an intrastromal corneal suture. Instituto Oftalmologico de Alicante, University of Alicante, Spain. Eighty eyes of 62 patients had endocapsular phacoemulsification. A foldable intraocular lens was implanted through a 4.0 mm clear corneal incision. A 10-0 nylon intrastromal corneal suture was used in all eyes. Change sin corneal astigmatism were calculated by vector analysis; follow-up was 6 months. Early and late suture-related complications were also evaluated. Mean induced cylinder was 1.25 diopters (D) +/- 1.24 (SD) with the wound 1 day postoperatively and 0.19 +/- 0.81 D against the wound at 6 months. There were no incision- or suture-related complications postoperatively. Use of the intrastromal corneal suture led to astigmatically neutral closure of multiplanar corneal incisions.

  2. Astigmatic intensity equation for electron microscopy based phase retrieval.

    Science.gov (United States)

    Petersen, Tim C; Keast, Vicki J

    2007-08-01

    Phase retrieval, in principle, can be performed in a transmission electron microscope (TEM) using arbitrary aberrations of electron waves; provided that the aberrations are well-characterised and known. For example, the transport of intensity equation (TIE) can be used to infer the phase from a through-focus series of images. In this work an "astigmatic intensity equation" (AIE) is considered, which relates phase gradients to intensity variations caused by TEM objective lens focus and astigmatism variations. Within the paraxial approximation, it is shown that an exact solution of the AIE for the phase can be obtained using efficient Fourier transform methods. Experimental requirements for using the AIE are the measurement of a through-focus derivative and another intensity derivative, which is taken with respect to objective lens astigmatism variation. Two quasi-experimental investigations are conducted to test the validity of the solution.

  3. Goos-Hänchen and Imbert-Fedorov shifts for astigmatic Gaussian beams

    Science.gov (United States)

    Ornigotti, Marco; Aiello, Andrea

    2015-06-01

    In this work we investigate the role of the beam astigmatism in the Goos-Hänchen and Imbert-Fedorov shift. As a case study, we consider a Gaussian beam focused by an astigmatic lens and we calculate explicitly the corrections to the standard formulas for beam shifts due to the astigmatism induced by the lens. Our results show that the different focusing in the longitudinal and transverse direction introduced by an astigmatic lens may enhance the angular part of the shift.

  4. LASIK for post penetrating keratoplasty astigmatism and myopia

    OpenAIRE

    WEBBER, S; Lawless, M.; Sutton, G; Rogers, C.

    1999-01-01

    AIMS—To report the results of a series of patients who were treated with LASIK to correct post penetrating keratoplasty ametropia.
METHODS—26 eyes of 24 patients underwent LASIK to correct astigmatism and myopia after corneal transplantation; 14 eyes also received arcuate cuts in the stromal bed at the time of surgery. The mean preoperative spherical equivalent was −5.20D and the mean preoperative astigmatism was 8.67D.
RESULTS—The results of 25 eyes are reported. The mean 1 month values for ...

  5. Influence of suture regularity on corneal astigmatism after penetrating keratoplasty.

    Science.gov (United States)

    Hjortdal, Jesper; Søndergaard, Anders; Fledelius, Walther; Ehlers, Niels

    2011-08-01

    To investigate whether suture regularity affects corneal astigmatism after keratoplasty. Twenty-one patients undergoing penetrating keratoplasty for various corneal diseases were included in the study. The grafts were sutured in place using a single-running Nylon 10-0 suture, taking 24 bites. Immediately after surgery, standard calibrated images of the grafted eye were captured and stored. Using a dedicated image analysis programme, stitches and needle points were identified, and a number of suture regularity variables were calculated. Corneal topographic images were obtained before suture removal (12 months after surgery) and 3 months after suture removal (18 months after surgery). Topographic measures of astigmatism [surface regularity (SRI), surface asymmetry index (SAI) and simulated keratometric astigmatism] were calculated and correlated with the computed suture regularity variables. The average stitch length was 3.04 ± 0.28 mm and the distance between the outer needle points was 2.53 ± 0.09 mm. The SRI was 1.26 ± 0.36 and the SAI was 1.59 ± 0.67 after 12 months; these decreased to 1.03 ± 0.48 and 0.92 ± 0.46 after 18 months, respectively. Corneal astigmatism was 6.38 ± 2.99 and 5.87 ± 3.13 dioptres after 12 and 18 months, respectively. Suture regularity did not affect SAI, SRI or corneal astigmatism significantly 12 months after surgery. Eighteen months after surgery (3 months after suture removal), the standard deviation on the original stitch length was found to significantly increase corneal astigmatism. In addition, the size of the counter-clockwise angle between stitch and graft radian was correlated significantly with a lower SRI. The origin of corneal astigmatism after penetrating keratoplasty is multifaceted. Regular stitch length and stitch advancement on the surface appears to improve the optical quality of the graft after suture removal. Factors such as stitch depth, suture tension and variations in wound construction might also be

  6. Impact of astigmatism and high-order aberrations on subjective best focus.

    Science.gov (United States)

    Marcos, Susana; Velasco-Ocana, Miriam; Dorronsoro, Carlos; Sawides, Lucie; Hernandez, Martha; Marin, Gildas

    2015-08-01

    We studied the role of native astigmatism and ocular aberrations on best-focus setting and its shift upon induction of astigmatism in 42 subjects (emmetropes, myopes, hyperopes, with-the-rule [WTR] and against-the-rule [ATR] myopic astigmats). Stimuli were presented in a custom-developed adaptive optics simulator, allowing correction for native aberrations and astigmatism induction (+1 D; 6-mm pupil). Best-focus search consisted on randomized-step interleaved staircase method. Each subject searched best focus for four different images, and four different conditions (with/without aberration correction, with/without astigmatism induction). The presence of aberrations induced a significant shift in subjective best focus (0.4 D; p < 0.01), significantly correlated (p = 0.005) with the best-focus shift predicted from optical simulations. The induction of astigmatism produced a statistically significant shift of the best-focus setting in all groups under natural aberrations (p = 0.001), and in emmetropes and in WTR astigmats under corrected aberrations (p < 0.0001). Best-focus shift upon induced astigmatism was significantly different across groups, both for natural aberrations and AO-correction (p < 0.0001). Best focus shifted in opposite directions in WTR and ATR astigmats upon induction of astigmatism, symmetrically with respect to the best-focus shift in nonastigmatic myopes. The shifts are consistent with a bias towards vertical and horizontal retinal blur in WTR and ATR astigmats, respectively, indicating adaptation to native astigmatism.

  7. Characteristics of astigmatism in Black South African high school ...

    African Journals Online (AJOL)

    ship to gender, age, school grade levels and spherical ametropia. Methods: .... The aim of this study was to determine the prevalence of astigmatism, and its types and investigate their associations with age, gender, grade levels and spherical ametropia. Methods ..... other studies in African populations12,14 may be related.

  8. Late onset post-keratoplasty astigmatism in patients with keratoconus

    OpenAIRE

    Lim, L; Pesudovs, K; Goggin, M.; Coster, D J

    2004-01-01

    Aim: 10 eyes of 10 patients are reported where progression of keratoconus in the host cornea occurred more than 10 years after penetrating keratoplasty with resultant increase in astigmatism. The technique and results of graft refractive surgery in seven eyes are presented.

  9. An Astigmatic Detection System for Polymeric Cantilever-based Sensors

    DEFF Research Database (Denmark)

    Hwu, En-Te; Liao, Hsien-Shun; Bosco, Filippo

    2012-01-01

    We demonstrate the use of an astigmatic detection system (ADS) for resonance frequency identification of polymer microcantilever sensors. The ADS technology is based on a DVD optical head combined with an optical microscope (OM). The optical head has a signal bandwidth of 80 MHz, allowing thermal...

  10. Effect of nylon suture diameter on induced astigmatism after phacoemulsification.

    Science.gov (United States)

    Mendívil, A

    1997-10-01

    To prospectively compare the clinical results of 10-0 and 9-0 monofilament nylon sutures after phacoemulsification with poly(methyl methacrylate) intraocular lens implantation through a 4.0 mm cruciate incision. Department of Ophthalmology, Ramón y Cajal Hospital, Madrid, Spain. One hundred eyes with cataract were randomly assigned to have surgery using a 10-0 or a 9-0 nylon suture. Except for suture diameter, identical surgical methods were used in every case. Data on uncorrected visual acuity, keratometry and postoperative astigmatism were analyzed up to 12 months after surgery. Both groups had similar uncorrected visual acuity. Mean postoperative corneal astigmatism was against the rule in the 10-0 nylon suture group and with the rule in the 9-0 nylon suture group. Significant differences were found between groups (P suture diameters offered satisfactory clinical results. Patients with preoperative with-the-rule astigmatism might benefit from 10-0 nylon sutures and those with preoperative against-the-rule astigmatism, from 9-0 nylon sutures.

  11. Characteristics of astigmatism in Black South African high school ...

    African Journals Online (AJOL)

    The parameters evaluated included visual acuity using the LogMAR chart and refractive errors measured using an autorefractor and then refined ... but not across regions. Keywords: Astigmatism prevalence, school children, South Africa. ... common vision anomaly in school-aged children,1-2 caus- es visual impairment (VI) ...

  12. Correction of low corneal astigmatism in cataract surgery

    Directory of Open Access Journals (Sweden)

    Pia Leon

    2015-08-01

    Full Text Available AIM: To evaluate and compare aspheric toric intraocular lens (IOL implantation and aspheric monofocal IOL implantation with limbal relaxing incisions (LRI to manage low corneal astigmatism (1.0-2.0 D in cataract surgery.METHODS:A prospective randomized comparative clinical study was performed. There were randomly recruited 102 eyes (102 patients with cataracts associated with corneal astigmatism and divided into two groups. The first group received toric IOL implantation and the second one monofocal IOL implantation with peripheral corneal relaxing incisions. Outcomes considered were:visual acuity, postoperative residual astigmatism, endothelial cell count, the need for spectacles, and patient satisfaction. To determine the postoperative toric axis, all patients who underwent the toric IOL implantation were further evaluated using an OPD Scan III (Nidek Co, Japan. Follow-up lasted 6mo.RESULTS: The mean uncorrected distance visual acuity (UCVA and the best corrected visual acuity (BCVA demonstrated statistically significant improvement after surgery in both groups. At the end of the follow-up the UCVA was statistically better in the patients with toric IOL implants compared to those patients who underwent implantation of monofocal IOL plus LRI. The mean residual refractive astigmatism was of 0.4 D for the toric IOL group and 1.1 D for the LRI group (P<0.01. No difference was observed in the postoperative endothelial cell count between the two groups.CONCLUSION: The two surgical procedures demonstrated a significant decrease in refractive astigmatism. Toric IOL implantation was more effective and predictable compared to the limbal relaxing incision.

  13. Astigmatism corrected common path probe for optical coherence tomography.

    Science.gov (United States)

    Singh, Kanwarpal; Yamada, Daisuke; Tearney, Guillermo

    2017-03-01

    Optical coherence tomography (OCT) catheters for intraluminal imaging are subject to various artifacts due to reference-sample arm dispersion imbalances and sample arm beam astigmatism. The goal of this work was to develop a probe that minimizes such artifacts. Our probe was fabricated using a single mode fiber at the tip of which a glass spacer and graded index objective lens were spliced to achieve the desired focal distance. The signal was reflected using a curved reflector to correct for astigmatism caused by the thin, protective, transparent sheath that surrounds the optics. The probe design was optimized using Zemax, a commercially available optical design software. Common path interferometric operation was achieved using Fresnel reflection from the tip of the focusing graded index objective lens. The performance of the probe was tested using a custom designed spectrometer-based OCT system. The probe achieved an axial resolution of 15.6 μm in air, a lateral resolution 33 μm, and a sensitivity of 103 dB. A scattering tissue phantom was imaged to test the performance of the probe for astigmatism correction. Images of the phantom confirmed that this common-path, astigmatism-corrected OCT imaging probe had minimal artifacts in the axial, and lateral dimensions. In this work, we developed an astigmatism-corrected, common path probe that minimizes artifacts associated with standard OCT probes. This design may be useful for OCT applications that require high axial and lateral resolutions. Lasers Surg. Med. 49:312-318, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  14. [The effect of corneal incision method on astigmatism after cataract extraction].

    Science.gov (United States)

    Smyk, A; Kropińska, E; Orzałkiewicz, A

    1998-01-01

    To assess the effect of the type of corneal incision and its closure on astigmatism after cataract extraction. Induced astigmatism was evaluated in 94 eyes after cataract extraction with IOL implantation 7 days, 1 month, 3 months, 6 months and 12 months after operation. 3 groups: were compared I--after extracapsular extraction with corneo-scleral incision (10 h-2 h) and continuous cross-like suture, II--after phacoemulsifications with scleral tunnel incision (3.3 mm) without suture. The highest induced astigmatism was observed 7 days after surgery in patients with the longest corneo-scleral incision with suture (group I). Induced astigmatism gradually decreased in time. In group after phacoemulsification especially with no suture low astigmatism with prompt stabilization was observed. The length and type of closure of the incision have an essential effect on induced astigmatism. Small incision, especially without suture induces minimal early postoperative astigmatism which remains stabile.

  15. The Changes in Corneal Astigmatism after Botulinum Toxin-A Injection in Patients with Blepharospasm

    Science.gov (United States)

    Moon, Nam Ju; Lee, Hyeon Il

    2006-01-01

    To determine if the involuntary contractions of eyelids may have any effects on the development of corneal astigmatism, we performed this prospective study which includes 19 patients with either essential blepharospasm or hemifacial spasm. In hemifacial spasm, the degree of corneal astigmatism was evaluated between two eyes. Then the topographic changes were checked using vector analysis technique before and after passively opening the eyelids. They were also measured before and at 1 and 6 months after the injection of Botulinum toxin. Resultantly, 20 eyes had the with-the-rule (group1) and 9 eyes against-the-rule (group2) astigmatism. In hemifacial spasm, significantly more astigmatism was found at spastic eyes. The corneal topographic changes after passively opening the eyelids showed 10 eyes with the astigmatic shift to the with-the-rule, while the remaining 19 to the against-the-rule. At 1 month after injection of Botulinum toxin, group 1 showed reduced average corneal astigmatism, whereas group 2 showed increased astigmatism. The astigmatic change vector showed significantly more against-the-rule. In the contrary, 6 months after treatment, corneal astigmatism again increased in group 1 and decreased in group 2. So they took on the appearance of pretreatment astigmatic status eventually. Conclusively eyelids may play an important role in corneal curvature. PMID:16479079

  16. Prevalence rates and epidemiological risk factors for astigmatism in Singapore school children.

    Science.gov (United States)

    Tong, Louis; Saw, Seang-Mei; Carkeet, Andrew; Chan, Wai-Ying; Wu, Hui-Min; Tan, Donald

    2002-09-01

    This study examined the prevalence rate of astigmatism and its epidemiological risk factors in Singapore school children. In a study of school children aged 7 to 9 years old in two schools in Singapore in 1999, a detailed questionnaire was administered to parents regarding reading or close-work habits, past history of close-work, family history, and socioeconomic factors. Cycloplegic refraction was performed five times in each eye. Defining astigmatism as worse than or equal to 0.5, 0.75, and 1 D cylinder in the right eye, the prevalence of astigmatism was calculated. The study population consisted of 1028 children. The prevalence rate of astigmatism (worse than or equal to 1 D cylinder) was 19.2% (95% confidence interval, 16.8 to 21.6). This was not different between genders, ethnic groups, or age (p > 0.05). With-the-rule astigmatism was more common than against-the-rule astigmatism. The prevalence of astigmatism and myopia was 9.8% (95% confidence interval, 8.0 to 11.6). A high AC/A ratio was associated (p = 0.003) with astigmatism, even after exclusion of myopic children. On vectorial analysis, J0 and J45 were associated with the number of hours of playing video games, whereas J45 was also associated with computer use. Only J45 was associated to male gender, a high AC/A ratio, and a family history of myopia. The prevalence rate of astigmatism (> or = 1 D) was 19%. Playing video games and computer use may be associated with astigmatism severity, although the presence of astigmatism (> or = 1 D) was not associated with any nearwork factors. A family history of myopia was associated with oblique astigmatism severity. A high AC/A ratio is associated with astigmatism, and this requires further investigation.

  17. Refractive and corneal astigmatism in white school children in northern ireland.

    Science.gov (United States)

    O'Donoghue, Lisa; Rudnicka, Alicja R; McClelland, Julie F; Logan, Nicola S; Owen, Christopher G; Saunders, Kathryn J

    2011-06-08

    To study the prevalence of and relation between refractive and corneal astigmatism in white school children in Northern Ireland and to describe the association between refractive astigmatism and refractive error. Stratified random clustering was used to recruit 1053 white children, 392 aged 6-7 years and 661 aged 12-13 years. Eye examinations included cycloplegic autorefraction and ocular biometric measures of axial length and corneal curvature. The prevalence of refractive astigmatism (≥ 1 DC) did not differ significantly between 6- to 7-year-old children (24%; 95% confidence interval [CI], 19-30) and 12- to 13-year-old children (20%; 95% CI, 14-25). The prevalence of corneal astigmatism (≥ 1 DC) also did not differ significantly between 6- to 7-year-old children (29%; 95% CI, 24-34) and 12- to 13-year-old children (25%; 95% CI, 21-28). While levels of refractive astigmatism and corneal astigmatism were similar, refractive astigmatism was predominantly oblique (76%; 95% CI, 67-85, of 6- to 7-year-olds; 59%; 95% CI, 48-70, of 12- to 13-year-olds), but corneal astigmatism was predominantly with-the-rule (80%; 95% CI, 72-87, of 6- to 7-year-olds; 82%; 95% CI, 74-90, of 12- to 13-year-olds). The prevalence of refractive astigmatism was associated with increasing myopia and hyperopia. This study is the first to provide robust population-based data on the prevalence of astigmatism in white school children in the United Kingdom. The prevalence of refractive astigmatism and corneal astigmatism is stable between 6 and 7 years and 12 and 13 years, although this finding would need to be confirmed by prospective studies. There is a high prevalence of refractive and corneal astigmatism which is associated with ametropia.

  18. Effect of Mitomycin C on Myopic versus Astigmatic Photorefractive Keratectomy

    Directory of Open Access Journals (Sweden)

    Ashwag A. Almosa

    2017-01-01

    Full Text Available Purpose. Long-term mitomycin C (MMC effects on photorefractive keratectomy (PRK were compared in simple myopic and astigmatic patients. Methods. In this observational cohort study, subjects were selected based on preoperative and postoperative data collected from medical records; they were divided into simple myopia with/without MMC and myopic astigmatism with/without MMC groups. Haze, uncorrected visual acuity (UCVA, best-corrected visual acuity (BCVA, subjective refraction, and K-reading were evaluated at 1-, 3-, 6-, and 12-month follow-ups. Results. One hundred fifty-nine eyes of 80 subjects (34 women and 46 men; mean age, 26.81 ± 7.74 years; range, 18–53 years; spherical powers, −0.50 to −8.00 DS; and cylindrical powers, −0.25 to −5.00 DC were enrolled. One year postoperatively, the simple myopia with/without MMC groups showed no difference in UCVA (P=0.187, BCVA (P=0.163, or spherical equivalent (P=0.163 and a significant difference (P=0.0495 in K-reading; the haze formation difference was nonsignificant (P=0.056. Astigmatic groups with/without MMC showed a significant difference in K-reading (P<0.0001. MMC groups had less haze formation (P<0.0001. Conclusion. PRK with intraoperative MMC application showed excellent visual outcomes. MMC’s effect on astigmatic patients was significantly better with acceptable safety and minimal side effects.

  19. Anisometropia prevalence in a highly astigmatic school-aged population.

    Science.gov (United States)

    Dobson, Velma; Harvey, Erin M; Miller, Joseph M; Clifford-Donaldson, Candice E

    2008-07-01

    To describe prevalence of anisometropia, defined in terms of both sphere and cylinder, examined cross-sectionally, in school-aged members of a Native American tribe with a high prevalence of astigmatism. Cycloplegic autorefraction measurements, confirmed by retinoscopy and, when possible, by subjective refraction were obtained from 1041 Tohono O'odham children, 4 to 13 years of age. Astigmatism > or =1.00 diopter (D) was present in one or both eyes of 462 children (44.4%). Anisometropia > or =1.00 D spherical equivalent (SE) was found in 70 children (6.7%), and anisometropia > or =1.00 D cylinder was found in 156 children (15.0%). Prevalence of anisometropia did not vary significantly with age or gender. Overall prevalence of significant anisometropia was 18.1% for a difference between eyes > or =1.00 D SE or cylinder. Vector analysis of between-eye differences showed a prevalence of significant anisometropia of 25.3% for one type of vector notation (difference between eyes > or =1.00 D for M and/or > or =0.50 D for J0 or J45), and 16.2% for a second type of vector notation (between-eye vector dioptric difference > or =1.41). Prevalence of SE anisometropia is similar to that reported for other school-aged populations. However, prevalence of astigmatic anisometropia is higher than that reported for other school-aged populations.

  20. [Choice of the site of incision for cataract surgery without suture according to preoperative astigmatism].

    Science.gov (United States)

    Roman, S; Givort, G; Ullern, M

    1997-01-01

    To compare surgically induced astigmatism, postoperative astigmatism and uncorrected visual acuity after cataract surgery depending on the site of a 4 mm sutureless incision (superior scleral or corneal temporal) and on the preoperative astigmatism. According to preoperative astigmatism and to the site of incision 4 groups have been distinguished. Group I: with-the-rule preoperative astigmatism and superior scleral incision, group II: with-the-rule preoperative astigmatism and corneal temporal incision, group III: against-the-rule preoperative astigmatism and superior scleral incision, group IV: against-the-rule preoperative astigmatism and temporal incision. The patients had a preoperative and postoperative (Day 1, 8, 30, 180, 360) keratometry. Surgically induced astigmatism, preoperative and postoperative astigmatism have been expressed according to Naeser method. The uncorrected visual acuity at Day 30 has been compared in each group. Preoperative astigmatism was similar in the four groups. Surgically induced astigmatism was -0.18 diopter (D) at day 30 and -0.41 D at day 360 for the scleral incisions and +0.60 D at day 30 and +0.33 D at day 360 for the temporal incisions. The postoperative astigmatism was +0.5 D at day 30 and +0.27 at day 360 for the group I and +1.22 D at day 30 and +0.95 D at day 360 for group II. There was no statistical difference in the uncorrected visual acuity. Postoperative astigmatism was -0.8 D at day 30 and -1.03 D at day 360 in group III and -0.04 D at day 30 and -0.31 D at day 360 in group IV. The visual acuity was significantly better in group IV than in group III. In cases of preoperative with-the-rule astigmatism incisions are possible. In cases of WTR astigmatism over 0.75 D we perform a superior scleral approach. In cases of against-the-rule astigmatism the temporal incision is the only one to consider.

  1. Comparison of Whole Eye vs. First-Surface Astigmatism in Down Syndrome

    Science.gov (United States)

    Knowlton, Rachel; Marsack, Jason D.; Leach, Norman E.; Herring, Ralph J.; Anderson, Heather A.

    2016-01-01

    Purpose Individuals with Down syndrome (DS) have structural differences in the cornea and lens, as compared to the general population. This study investigates objectively measured refractive and corneal astigmatism, as well as calculated internal astigmatism in subjects with and without DS. Methods Refractive (Grand Seiko autorefraction) and anterior corneal astigmatism (difference between steep and flat keratometry obtained with Zeiss Atlas corneal topography) were measured in 128 subjects with DS (mean age = 24.8±8.7 yrs) and 137 controls without DS (mean age = 24.9±9.9 yrs), with 1 eye randomly selected for analysis per subject. Refractive astigmatism and corneal astigmatism were converted to vector notation (J0, J45) to calculate internal astigmatism (Refractive – Corneal) and then converted back to minus cylinder form. Results Mean refractive astigmatism was significantly greater in subjects with DS than controls (−1.94±1.30DC vs −0.66±0.60DC, t=−10.16, p<0.001), as was mean corneal astigmatism (1.70±1.04DC vs 1.02±0.63DC, t=6.38, p<0.001) and mean internal astigmatism (−1.07±0.68DC vs −0.77±0.41DC, t=−4.21, p<0.001). A positive linear correlation between corneal and refractive astigmatism was observed for both study populations for both the J0 and J45 vectors (p<0.001 for all comparisons, R2 range = 0.31 to 0.74). The distributions of astigmatism orientation differed significantly between the two study populations when compared across all three types of astigmatism (Chi-Square, p<0.001). Conclusions This study demonstrates that corneal astigmatism is predictive of overall refractive astigmatism in individuals with DS, as it is in the general population. The greater magnitudes of astigmatism and wider variation of astigmatism orientation in individuals with DS for refractive, corneal, and calculated internal astigmatism is likely attributable to previously reported differences in the structure of the cornea and internal optical components

  2. The effect of different suturing techniques on astigmatism after penetrating keratoplasty.

    Science.gov (United States)

    Kim, Sang Jin; Wee, Won Ryang; Lee, Jin Hak; Kim, Mee Kum

    2008-12-01

    The purpose of this study was to compare the effects on astigmatism after penetrating keratoplasty with three different suture techniques. In this prospective study, 38 eyes of 38 patients underwent penetrating keratoplasty with three suturing techniques: interrupted, single running, and double running. Topographic astigmatism was measured at 2, 6, 12, and 18 months after keratoplasty. During 18 months after surgery, the interrupted suture group had higher astigmatism than the double running suture group. There was no significant difference in the amounts of astigmatism during the first year after keratoplasty between the single running and the double running suture group. However, at 18 months after surgery, when all sutures were out, the double running suture group (3.60+/-1.58 diopters) showed significantly less astigmatism than the single running group (5.65+/-1.61 diopters). In conclusion, post-keratoplasty astigmatism was the least in the double running suture group of the three suturing techniques at 18 months after penetrating keratoplasty.

  3. Plasma channels during filamentation of a femtosecond laser pulse with wavefront astigmatism in air

    Energy Technology Data Exchange (ETDEWEB)

    Dergachev, A A; Kandidov, V P; Shlenov, S A [Lomonosov Moscow State University, Faculty of Physics, Moscow (Russian Federation); Ionin, A A; Mokrousova, D V; Seleznev, L V; Sinitsyn, D V; Sunchugasheva, E S; Shustikova, A P [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2014-12-31

    We have demonstrated experimentally and numerically the possibility of controlling parameters of plasma channels formed during filamentation of a femtosecond laser pulse by introducing astigmatism in the laser beam wavefront. It is found that weak astigmatism increases the length of the plasma channel in comparison with the case of aberration-free focusing and that strong astigmatism can cause splitting of the plasma channel into two channels located one after another on the filament axis. (interaction of laser radiation with matter. laser plasma)

  4. The Effect of Different Suturing Techniques on Astigmatism after Penetrating Keratoplasty

    OpenAIRE

    Kim, Sang Jin; Wee, Won Ryang; Lee, Jin Hak; Kim, Mee Kum

    2008-01-01

    The purpose of this study was to compare the effects on astigmatism after penetrating keratoplasty with three different suture techniques. In this prospective study, 38 eyes of 38 patients underwent penetrating keratoplasty with three suturing techniques: interrupted, single running, and double running. Topographic astigmatism was measured at 2, 6, 12, and 18 months after keratoplasty. During 18 months after surgery, the interrupted suture group had higher astigmatism than the double running ...

  5. [Induced astigmatism in extracapsular cataract extraction with tunnel incision and various wound closures].

    Science.gov (United States)

    Häberle, H; Anders, N; Pham, D T; Wollensak, J

    1995-09-01

    For planned extracapsular cataract extraction the no-stitch technique with 11-mm tunnel width has been well established. Four modifications of wound closure were performed to further reduce surgically induced astigmatism. In this prospective study we controlled 250 eyes of 250 consecutive patients 4 months after surgery with four different wound constructions: sutureless wound closure (n = 70), singular perpendicular suture (n = 100), cross suture (n = 40) in 12 o'clock position or sutureless wound closure in temporal position (n = 40). Surgically 'Induced Astigmatism' was for eyes with preoperative 'With the Rule Astigmatism' (vs Against the Rule astigmatism), operation in 12 o'clock position and sutureless wound closure 2.22 +/- 0.77 D (1.66 +/- 0.94 D), with perpendicular suture 1.66 +/- 0.93 D (1.24 +/- 0.82 D), and with cross suture 1.47 +/- 0.96 D (0.9 +/- 1.13 D). Temporal incision was only performed in preoperative 'Against-the-Rule-Astigmatism' eyes and resulted in 0.6 D of 'Induced Astigmatism'. Preoperative average astigmatism was 0.86 +/- 0.68 D (1.01 +/- 0.95 D). For preoperative 'With the Rule Astigmatism', operation in 12 o'clock position and singular perpendicular suture and for 'Against the Rule Astigmatism' (especially > 1.5 D) temporal incision is recommended.

  6. Longitudinal Outcomes of U.S. Air Force Pilot Applicants With Waivered Astigmatism.

    Science.gov (United States)

    Andrus, David E; Haynes, Jared T; Wright, Steven T

    2017-03-01

    Current U.S. Air Force medical standards allow applicants to enter pilot training with up to 1.50 D of astigmatism. However, waivers are considered for individuals with up to 3.00 D of astigmatism. Although typically a benign finding, higher levels of astigmatism may be progressive and can be associated with corneal ectasia (e.g., keratoconus or pellucid marginal degeneration) leading to reduced visual acuity with spectacles and/or soft contact lenses. The goal of this study was to evaluate the long-term outcomes of pilot applicants waivered into training with astigmatism exceeding the aeromedical standard. Subjects were identified on the basis of their enrollment in the Excessive Astigmatism Management Group maintained by the Aeromedical Consultation Service, Ophthalmology branch at Wright-Patterson Air Force Base, Ohio. Metrics evaluated included refractive status, visual acuity, aeromedical waiver status, safety data, and the development of corneal ectasia. Seventy-six subjects were tracked for up to 10 years, with an average follow-up period of 5.5 years. Mean astigmatism at initial examination was 1.91 D, although mean astigmatism on the basis of the most recent examination was 2.19 D. Subjects with excessive astigmatism who were waivered into pilot training showed an average increase in astigmatism of slightly less than 0.05 D annually, which equates to a total increase in astigmatism of approximately 0.25 D for the duration of the study. No subjects developed ectasia or were disqualified from flying for vision or refractive reasons. No mishaps were identified with vision being a causative or contributing factor. This study supports continuation of current Air Force waiver policy, although a longer follow-up period is required to consider modifying the aeromedical standard for astigmatism. Reprint & Copyright © 2017 Association of Military Surgeons of the U.S.

  7. The influence of unilateral uncorrected astigmatism on binocular vision and fixation disparity.

    Science.gov (United States)

    Nilsson, April; Nilsson, Maria; Stevenson, Scott B; Brautaset, Rune L

    2011-12-01

    It is accepted practice to use a spherical equivalent power as an alternative contact lens correction for those patients with lower amounts of astigmatism, allowing for an easier fit, but the blur caused by one diopter of uncorrected astigmatism can reduce acuity of 6/6 to that of about 6/8. This is usually deemed acceptable monocularly, often retaining a good binocular acuity. The purpose of this study is to explore how monocular astigmatic blur may also affect the patient's binocular vision function. A trial frame was outfitted with full correction for 20 healthy subjects (mean age 25.5 years, range 19-36 years) and a baseline horizontal fixation disparity was measured at a distance of 1 m. Thereafter, fixation disparity was measured with induced monocular astigmatic blur in the right eye, creating an astigmatic error in the amounts of -0.75 and -1.25 in axis 90 and axis 45. It was determined that the differences among full correction and the 4 different types of astigmatic blur were not significant when analyzed as one group (P = 0.5445), nor when separated into groups according to whether the subject had naturally occurring astigmatism or not, (astigmatic group, P = 0.3801; non-astigmatic group, P = 0.5899). Monocular astigmatic blur in the amounts of -0.75 and -1.25 did not have a significant effect on tested subjects with regard to the amount of blur or axis orientation. This low amount of blur is likely within the range of compensation for the subjects, proving that spherical equivalent contact lenses are a viable option for low amounts of astigmatic error.

  8. Management of postkeratoplasty astigmatism by paired arcuate incisions with compression sutures.

    Science.gov (United States)

    Fares, Usama; Mokashi, Aashish A; Al-Aqaba, Mouhamed Ali; Otri, Ahmad Muneer; Miri, Ammar; Dua, Harminder Singh

    2013-04-01

    To analyse the efficacy of paired arcuate incisions and compression sutures technique in the management of post penetrating keratoplasty (PK) astigmatism. A paired arcuate incision with compression sutures procedure was used to treat 26 eyes with post-PK astigmatism ranging from 6.00 to 16.50 dioptres (D). The incisions were placed at the 7.0 mm optical zone inside the graft-host junction at a depth of 80% of corneal thickness. A 45° paired arc length was planned for eyes with preoperative astigmatism between 6D and 9D, and a 60° paired arc length was planned for eyes with preoperative astigmatism of >9D. At 3 months, corneal topography and refraction was performed and suture(s) removed if indicated. Net and vector astigmatism changes were calculated to determine the efficacy of the procedure. The indications for PK included keratoconus, Fuch's endothelial dystrophy, pseudophakic bullous keratopathy and corneal scar. There was a statistically significant reduction in the mean magnitude of astigmatism from 9.66 ± 2.90D preoperatively to 4.37 ± 2.53D postoperatively in the whole group. The mean decrease in the astigmatism was 4.37 ± 2.05D (58.4%) and 6.23 ± 3.63D (52.6%) in patients with 6-9D and >9D, respectively. Vector power calculations also showed a significant astigmatism reduction in all groups. The safety and efficacy indices were 1.40 and 0.28, respectively. Manual astigmatic keratotomy is a viable technique with relatively good safety and efficacy outcomes. Based on the results we propose that increasing the arc length to a minimum of 60° for astigmatism of 6-9D, and to 75° for astigmatism >9D, is likely to have a greater beneficial effect.

  9. Finite element simulation of arcuates for astigmatism correction.

    Science.gov (United States)

    Lanchares, Elena; Calvo, Begoña; Cristóbal, José A; Doblaré, Manuel

    2008-01-01

    In order to simulate the corneal incisions used to correct astigmatism, a three-dimensional finite element model was generated from a simplified geometry of the anterior half of the ocular globe. A hyperelastic constitutive behavior was assumed for cornea, limbus and sclera, which are collagenous materials with a fiber structure. Due to the preferred orientations of the collagen fibrils, corneal and limbal tissues were considered anisotropic, whereas the sclera was simplified to an isotropic one assuming that fibrils are randomly disposed. The reference configuration, which includes the initial strain distribution that balances the intraocular pressure, is obtained by an iterative process. Then the incisions are simulated. The final positions of the nodes belonging to the incised meridian and to the perpendicular one are fitted by both radii of curvature, which are used to calculate the optical power. The simulated incisions were those specified by Lindstrom's nomogram [Chu, Y., Hardten, D., Lindquist, T., Lindstrom, R., 2005. Astigmatic keratotomy. Duane's Ophthalmology. Lippincott Williams and Wilkins, Philadelphia] to achieve 1.5, 2.25, 3.0, 4.5 and 6.0D of astigmatic change, using the next values for the parameters: length of 45 degrees , 60 degrees and 90 degrees , an optical zone of 6mm, single or paired incisions. The model gives results similar to those in Lindstrom's nomogram [Chu et al., 2005] and can be considered a useful tool to plan and simulate refractive surgery by predicting the outcomes of different sorts of incisions and to optimize the values for the parameters involved: depth, length, position.

  10. [Evaluation of early postoperative astigmatism with respect to anterior chamber opening].

    Science.gov (United States)

    Jurowski, Piotr

    2003-01-01

    The study evaluates amount and direction of postoperative astigmatism after usually performed techniques of cataract surgery. 90 consecutive patients (120 eyes) mean aged 74.5 years, who underwent cataract surgery with clear corneal superior (Group 1) or temporal incision (Group 2), sclero-corneal tunnel sutureless incision (Group 3) or limbal ECCE incision with x sutures (Group 4), were examined with respect to postoperative astigmatism. Anterior chamber opening was determined by primary astigmatism and nucleus hardness. All measurements were performed based on keratometry. The highest mean value of with the rule astigmatism was assessed in Group 4. From the other hand, the least value were determined in group 2--95% with the rule and 5% oblique and in group 1--40% with the rule, 40% against the rule 20% oblique. In group 3, the value of postoperative astigmatism was higher, as compared with Group 1 and 2. It was assessed with similar proportion as in Group 1. At present cataract surgery techniques are not free of induced astigmatism. Study demonstrates significance of preoperative primary astigmatism assessment, with respect to surgery technique, to avoid postoperative astigmatism.

  11. Corneal wedge excision in the treatment of high astigmatism after penetrating keratoplasty.

    Science.gov (United States)

    Ezra, Daniel G; Hay-Smith, Graham; Mearza, Ali; Falcon, Mike G

    2007-08-01

    To report 5 cases of high astigmatism after penetrating keratoplasty (PK) treated with corneal wedge excisions. We report our experience of 5 patients treated with corneal wedge excisions for high astigmatism after PK. A thin sliver of cornea measuring between 0.1 and 0.2 mm in thickness was excised from just inside the graft-recipient interface. The length of the incision centered at the axis of the flatter meridian of the cornea and was extended over a range of 60-90 degrees. The wound was closed with interrupted 10-0 nylon sutures placed every 15 degrees. We also report, for the first time, both pre- and postoperative corneal topography in 3 of our patients who underwent wedge excisions. The mean preoperative astigmatism was 15.2 D (range, 8.5-29.1 D). Postoperatively, after wedge excision, the mean astigmatism was reduced to 2.3 D (range, 1.9-3.7 D). The mean reduction in astigmatism was 12.9 D (range, 6.3-25.4 D). Corneal wedge resection is an effective treatment for high astigmatism after PK. It may prove particularly useful in cases of high astigmatism or where other treatments are not appropriate. We believe that there is still a role for wedge resection as one of many tools to be used in the treatment of high post-PK astigmatism.

  12. Intrastromal Corneal Ring Segments for Astigmatism Correction after Deep Anterior Lamellar Keratoplasty

    Science.gov (United States)

    Coscarelli, Sandro; Ferrara, Paulo; Araújo, Luana P. N.; Ávila, Marcos; Torquetti, Leonardo

    2017-01-01

    Background. To evaluate the change in corneal astigmatism after intrastromal corneal ring segment (ICRS) implantation in keratoconus patients with previous deep anterior lamellar keratoplasty (DALK). Design was a longitudinal, retrospective, interventional study. The study included 25 eyes of 24 patients with keratoconus who had DALK performed at least two years prior to ICRS implantation. All patients had a clear corneal graft with up to 8.00 D of corneal astigmatism and intolerance to contact lenses. The studied parameters were age, sex, corrected distance visual acuity (CDVA), maximum keratometry (K1), minimum keratometry (K2), spherical equivalent, and astigmatism. There was a statistically significant decrease in the postintervention analysis as follows: 3.5 D reduction in K1 (p astigmatism reduced from 3.87 D preoperatively to 1.90 D postoperatively (p astigmatism after DALK as it yields significant visual, topographic, and refractive results. PMID:28951784

  13. The relationship between patient age and astigmatism magnitude after congenital cataract surgery.

    Science.gov (United States)

    Bar-Sela, Shai; Glovinsky, Yoseph; Wygnanski-Jaffe, Tamara; Spierer, Abraham

    2009-01-01

    To evaluate the magnitude of refractive astigmatism after congenital cataract surgery and to define its correlation with patient age. The authors retrospectively reviewed the charts of all pediatric patients who underwent congenital cataract extraction with intraocular lens (IOL) implantation through a 3.0-mm clear corneal incision from 1998 to 2003, and had no suture removal for 5 months afterward. Thirty-four children were included, aged 2 months to 15 years. Refractive astigmatism was assessed manually 1 week, 3 months, and 5 months after surgery by an experienced optometrist. The paired t test was used to compare the magnitude of postoperative astigmatism at different postoperative periods. Spearman correlation was used to determine the correlation between patient age and the postoperative refractive astigmatism. Mean refractive astigmatism in all patients was 1.8+/-1.5 diopters (D) at 1 week postoperatively. It significantly decreased to 1.0+/-0.7 D at 3 months postoperatively (p=0.001), and to 0.8+/-0.7 D at 5 months postoperatively (p=0.03). The change in astigmatism was significantly greater during the first 3 postoperative months than during the following 2 months (p=0.04). Patient age was significantly correlated with 1 week postoperative astigmatism (Spearman coefficient, r = -0.46; p=0.006) and with 3 months postoperative astigmatism (Spearman coefficient, r =-0.37; p=0.03). Congenital cataract surgery using a small, clear corneal incision for IOL implantation caused high early postoperative astigmatism, which spontaneously regressed thereafter. Younger patients had higher early postoperative astigmatism.

  14. Single application on iris localization technology in excimer laser for astigmatism

    Directory of Open Access Journals (Sweden)

    Jun-Hua Hao

    2014-06-01

    Full Text Available AIM:To discuss the single application on iris localization technology in excimer laser for the treatment of astigmatism. METHODS:Totally 203 cases(406 eyesof laser in situ keratomileusis(LASIKin the treatment of compound myopic astigmatism patients were operated from November 2011 to November 2012 in our hospital. They were divided into two groups. One was observation group using iris localization and the other was control group using routine operation. Patients in the observation group of 100 cases(200 eyes, aged 18-43 years old, spherical diopter was -1.25 to -8.75D, astigmatism was -1.0 to -3.25D. In control group, 103 patients(206 eyes, aged 19-44 years old, spherical diopter was -1.75-9.50D, astigmatism was -1.0 to -3.25D. The patients in the observation group before the application of WaveScan aberrometer check for iris image, spherical lens, cylindrical lens and astigmatism axis data operation, only single application of iris location, without using wavefront aberration guided technology, laser cutting patterns for conventional LASIK model, spherical, cylindrical mirror and astigmatism axis data source to preoperative wavefront aberration results. The control group received routine LASIK. It was applicated comprehensive optometry optometry respectively to examine astigmatism and axial, based on the computer analysis during the preoperative, 1wk after the operation, and 6mo. Analysis of using SPSS 17 statistical software, it was independent-sample t test between the two groups of residual astigmatism and astigmatism axis. RESULTS:Postoperative residual astigmatism, the observation group was significantly better than the control group. Astigmatism axial measurement after operation, the observation group was significantly less than that of the control group. Postoperative visual acuity at 6mo, the observation group was better than that of the control group. The difference was statistically significant. CONCLUSION: For patients who cannot

  15. [Induced astigmatism after corneal suture removal after cataract surgery].

    Science.gov (United States)

    Loriaut, P; Kaswin, G; Rousseau, A; Meziani, L; M'nafek, N; Pogorzalek, N; Labetoulle, M

    2014-03-01

    To evaluate the time until astigmatic stabilization after corneal suture removal after cataract surgery. A prospective study was performed on 13 patients who had undergone cataract surgery by phacoemulsification with 2.4mm incision, for whom it was felt necessary to remove a corneal suture. A specular corneal topography was performed by OPD Scan before removal, immediately after, then 10, 20, 30 minutes and 15 days later. For each acquisition, the keratometric readings at the steepest (Kmax) and the flattest (Kmin) meridians (central at 1.15 mm from corneal center, intermediate at 2.30 mm and peripheral at 3.30 mm) and the amount of corneal astigmatism were measured. Corneal topography of 13 patients was acquired. Mean age was 70 ± 12 years. Mean time after cataract surgery was 23 ± 14 days. The greatest change in Kmax occurred within the first minutes following suture removal for the central and intermediate cornea (mean variation of -4.38% and -4.59% of initial Kmax respectively, i.e. -2.04 D ± 3.14 D et -2.15 D ± 3.11 D) whereas it was observed between 0 and 10 minutes for the peripheral area (mean 1.57% of Kmax after suture removal i.e. 0.96 D ± 1.85 D). Mean change in corneal astigmatism between 30 minutes and day 15 was 0.08 D ± 0.31 D (3.6% of baseline). When suture removal was performed between 7 and 10 days postoperatively, mean change was 0.16 D ± 0.24 D, whereas it was 0.03 D ± 0.34 D when performed after four weeks. Keratometric readings vary only slightly beyond the first 30 minutes after suture removal. These results suggest that the refraction could be accurately measured the same day as suture removal, with no additional follow-up absolutely necessary in order to prescribe the final spectacles. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  16. Changes in Anterior, Posterior, and Total Corneal Astigmatism after Descemet Membrane Endothelial Keratoplasty

    Science.gov (United States)

    Zumhagen, Lars; Rosentreter, André; Eter, Nicole

    2017-01-01

    Purpose. To evaluate changes in anterior, posterior, and total corneal astigmatism in patients after Descemet membrane endothelial keratoplasty (DMEK). Methods. We retrospectively included 29 eyes of 23 patients (age 67.6 ± 9.8 years, 13 female, 10 male) after DMEK surgery. The magnitude and axis orientation of anterior, posterior, and total corneal astigmatism before and after DMEK were determined using a rotating Scheimpflug system (Pentacam HR, Oculus). Results. The magnitude of anterior, posterior, and total corneal astigmatism in the central cornea did not change significantly after surgery. Before surgery, we found a significant correlation between the magnitudes of anterior and posterior corneal astigmatism (Spearman's correlation coefficient (rS) = 0.526, P = 0.003), while after surgery this correlation was no longer significant (rS = 0.038, P = 0.843). There was a significant correlation between the vector difference between preoperative and postoperative posterior astigmatism and the change in corneal pachymetry (rP = 0.47, P = 0.010). Conclusions. Posterior corneal astigmatism (especially the orientation) and therefore the relationship between anterior and total corneal astigmatism may change after DMEK. This should be considered to improve the accuracy of toric IOL power calculations following phakic DMEK or in combined procedures. PMID:28553547

  17. Changes in Anterior, Posterior, and Total Corneal Astigmatism after Descemet Membrane Endothelial Keratoplasty

    Directory of Open Access Journals (Sweden)

    Maged Alnawaiseh

    2017-01-01

    Full Text Available Purpose. To evaluate changes in anterior, posterior, and total corneal astigmatism in patients after Descemet membrane endothelial keratoplasty (DMEK. Methods. We retrospectively included 29 eyes of 23 patients (age 67.6 ± 9.8 years, 13 female, 10 male after DMEK surgery. The magnitude and axis orientation of anterior, posterior, and total corneal astigmatism before and after DMEK were determined using a rotating Scheimpflug system (Pentacam HR, Oculus. Results. The magnitude of anterior, posterior, and total corneal astigmatism in the central cornea did not change significantly after surgery. Before surgery, we found a significant correlation between the magnitudes of anterior and posterior corneal astigmatism (Spearman’s correlation coefficient rS=0.526, P=0.003, while after surgery this correlation was no longer significant (rS=0.038, P=0.843. There was a significant correlation between the vector difference between preoperative and postoperative posterior astigmatism and the change in corneal pachymetry (rP=0.47, P=0.010. Conclusions. Posterior corneal astigmatism (especially the orientation and therefore the relationship between anterior and total corneal astigmatism may change after DMEK. This should be considered to improve the accuracy of toric IOL power calculations following phakic DMEK or in combined procedures.

  18. Alpins and thibos vectorial astigmatism analyses: proposal of a linear regression model between methods

    Directory of Open Access Journals (Sweden)

    Giuliano de Oliveira Freitas

    2013-10-01

    Full Text Available PURPOSE: To determine linear regression models between Alpins descriptive indices and Thibos astigmatic power vectors (APV, assessing the validity and strength of such correlations. METHODS: This case series prospectively assessed 62 eyes of 31 consecutive cataract patients with preoperative corneal astigmatism between 0.75 and 2.50 diopters in both eyes. Patients were randomly assorted among two phacoemulsification groups: one assigned to receive AcrySof®Toric intraocular lens (IOL in both eyes and another assigned to have AcrySof Natural IOL associated with limbal relaxing incisions, also in both eyes. All patients were reevaluated postoperatively at 6 months, when refractive astigmatism analysis was performed using both Alpins and Thibos methods. The ratio between Thibos postoperative APV and preoperative APV (APVratio and its linear regression to Alpins percentage of success of astigmatic surgery, percentage of astigmatism corrected and percentage of astigmatism reduction at the intended axis were assessed. RESULTS: Significant negative correlation between the ratio of post- and preoperative Thibos APVratio and Alpins percentage of success (%Success was found (Spearman's ρ=-0.93; linear regression is given by the following equation: %Success = (-APVratio + 1.00x100. CONCLUSION: The linear regression we found between APVratio and %Success permits a validated mathematical inference concerning the overall success of astigmatic surgery.

  19. Impact of incision position of phacoemulsification cataract exaction on corneal astigmatism

    Directory of Open Access Journals (Sweden)

    Ming-Yan Zhai

    2014-09-01

    Full Text Available AIM: To compare the impact of different incision positions of phacoemulsification cataract exaction on corneal astigmatism. METHODS:Totally 412 patients(456 eyeswho had undergone the phacoemulsification and IOL implantation from June 2006 to June 2013 were randomly divided into two groups(each 228 eyes: observation group(incision above the middle of the limbus for the rule astigmatism, at the temporal for against the rule astigmatism, at the top of the temporal regulation on the maximum curvature of the meridian of the cornea for oblique astigmatism, at the top of the temporal for patients without astigmatism; control group(incision at top and middle of limbus, using a 3mm cornea scleral tunnel incision without suture, 2mm from the limbus. Corneal refractive status of preoperative and postoperative at different times were detected by corneal refractive, comparing the impact of different surgical incision on postoperative corneal astigmatism. RESULTS:The visual acuity of 1, 3mo postoperative of observation group was significantly better than the control group(PPPPCONCLUSION:Incision at the corneal curvature of the largest radial could correct preoperative astigmatism and improve visual acuity to a certain extent.

  20. Fifth-order theory of astigmatism of thin spherical spectacle lenses.

    Science.gov (United States)

    Miks, Antonin; Novak, Jiri

    2011-11-01

    To demonstrate and analyze the fifth-order theory of oblique astigmatism of a thin spherical spectacle lens and make a comparison with the third-order theory and exact ray tracing. Fifth-order equations were derived and used for analysis of oblique astigmatism of a spherical spectacle lens to calculate analytically the shape of the lens with corrected oblique astigmatism for large angles of field of view. These results were compared with those of finite ray tracing and the third-order aberration theory. Formulas for the calculation of oblique astigmatism of a thin spherical spectacle lens were derived. These formulas analytically express oblique astigmatism of the third and fifth order. The theory presented generalizes the third-order description of astigmatism of the spherical spectacle lens and derived equations enable calculation of the shape of the spectacle lens with corrected astigmatism even for a large field of view. The fifth-order solution is compared with the third-order theory and the exact solution found by ray tracing. Differences between the third- and fifth-order theory are spectacle lens, and the third-order theory is satisfactory for practical calculations in optometry.

  1. Effect of the chosen incision on corneal astigmatism after implantable collamer lens surgery

    Directory of Open Access Journals (Sweden)

    Xia Jiang

    2014-06-01

    Full Text Available AIM: To evaluate the effect of the chosen incision on corneal astigmatism after implantable collamer lens(ICLsurgery.METHODS: The study included 195 eyes of 102 patients, and all eyes were randomly divided into two groups: the chosen incision group(Group A, 97 eyesand temporal corneal incision(Group B, 98 eyes. Before the operation, and 1wk,1mo and 3mo after the operation, each patient was examined with corneal topography to observe the changes of corneal astigmatism. RESULTS: Preoperative corneal astigmatisms were(1.26±0.35D in group A and(1.28±0.38D in group B, thus there was no statistically significant difference(P>0.05. One week postoperatively, the astigmatism were(0.93±0.29D in group A and(1.32±0.33D in group B. One month postoperatively, the astigmatism were(0.85±0.16D in group A and(1.27±0.18D in group B. Three months postoperatively, the astigmatism were(0.80±0.13D in group A and(1.25±0.20D in group B. The differences between the two groups were statistically significant(PCONCLUSION: The chosen incision can reduce postoperative astigmatism to a certain extent after ICL surgery.

  2. Corneal topography-guided penetrating keratoplasty and suture adjustment: new approach for astigmatism control.

    Science.gov (United States)

    Vinciguerra, Paolo; Epstein, Daniel; Albè, Elena; Spada, Fernando; Incarnato, Nadia; Orzalesi, Nicola; Rosetta, Pietro

    2007-07-01

    To describe a new keratoplasty procedure using intraoperative topography to reduce postoperative astigmatism. One hundred sixty-five eyes of 150 consecutive patients were enrolled in this prospective study. The most common diagnosis was keratoconus (78.8%). As many as 5.5% had post-laser in situ keratomileusis ectasia. Keratoplasty was performed with the Hanna Corneal Trephine System. A 24-bite running suture was placed, using a specially developed marker. Suture adjustment was performed with the aid of an intraoperative topographer (Keratron Scout; OPTIKON 2000, Rome, Italy). The aim of the adjustment was to obtain an astigmatism 3.0 D of astigmatism at 1 month after surgery, suture adjustment was performed using the same intraoperative topographer. At 12 months postoperatevely (suture in), data from 108 (64%) eyes were available. The mean refractive astigmatism was 3.53 D, and the mean topographical astigmatism was 4.7 D. At 18 months (suture out), data from 32 eyes (19.4%) were available, and at 24 months, data from 29 eyes (13.3%) were available. The mean refractive astigmatism was 3.39 D at 18 months and 3.47 D at 24 months. The mean topographic astigmatism was 2.30 D at 18 months and 1.76 D at 24 months. Mean best spectacle-corrected visual acuity (BSCVA) was 0.51 at 3 months, 0.63 at 12 months (suture in), 0.67 at 18 months (suture out), and 0.78 at 24 months postoperatively. The combination of intraoperative topography and a 24-bite single running suture resulted in a stable astigmatism throughout the follow-up period, even after suture removal. BSCVA reached a 20/40 level as early as 3 months postoperatively and continued to rise after suture removal. The stability of astigmatism and BSCVA shortened the postoperative visual rehabilitation time and provided a high quality of vision early in the postoperative period.

  3. [Now soft toric contact lenses; silicone hydrogel lens for astigmatism].

    Science.gov (United States)

    Radu, Simona

    2006-01-01

    Soft toric contact lenses are a good alternative for the optical correction of astigmatism. They provide a wide visual field, quick adaptation process, negligible aniseikonia, together with enhanced comfort and reduced incidence of complications introduced by the lenses for frequent replacement. Still practitioners do not recommend them proactively and the satisfaction obtained by the patients is not high enough. This paper presents two recent studies that investigate the opinions of specialists and contact lens wearers and introduce a new contact lens, with an original design, born after 30 years of domination of only 2 modalities of rotational stabilization: prism ballast and dual thin zones. The lens is manufactured using a silicon-hydrogel material of 2-nd generation that provides sustained comfort and better oxygenation.

  4. [Correction of irregular astigmatism with intracorneal ring segments].

    Science.gov (United States)

    Touboul, D; Pinsard, L; Mesplier, N; Smadja, D; Colin, J

    2012-03-01

    Management of irregular astigmatism with intracorneal rings segments is an intrastromal additive technique developed initially for myopia but eventually popularized for keratoconus and post LASIK ectasia. ICR's are indicated for rigid contact lens intolerance, as an alternative to corneal transplantation. The mechanism of action is complex and involves biomechanical changes leading to a centering and a flattening of the ectasia. The surgical procedure has become much easier thanks to the use of femtosecond lasers. Individualized implantation strategies, based on each patient's topographic and tomographic pattern, are constantly evolving. Patients' refraction and vision are usually improved in more than 70% of cases. Complications remain very rare. Intracorneal ring segments can often be combined with other types of keratoplasty, usually in a sequential fashion, so as to optimize functional results. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  5. Fluoroperm extended wear RGP contact lenses for myopia, hyperopia, aphakia, astigmatism, and keratoconus.

    Science.gov (United States)

    Kastl, P R; Johnson, W C

    1989-01-01

    One hundred fifteen eyes of 62 patients were fit with paflufocon-A (Fluoroperm) rigid gas permeable (RGP) contact lenses. Patients included myopes, hyperopes, aphakes, and keratoconic and astigmatic patients; the latter patients were fit with bitoric designs for large amounts of corneal astigmatism or front toric designs for residual astigmatism. Thirty of the 52 patients (58%) who completed the study were able to wear the lenses continuously without complications; six (12%) were able to achieve extended wear for up to one month. The average visual acuity across the study was 20/20. Three complications were observed, resulting in a complication rate of 6%.

  6. Sequential selective same-day suture removal in the management of post-keratoplasty astigmatism

    National Research Council Canada - National Science Library

    Fares, U; Mokashi, A A; Elalfy, M S; Dua, H S

    2013-01-01

    In a previous study, we proposed that corneal topography performed 30-40 min after the initial suture removal can identify the next set of sutures requiring removal, for the treatment of post-keratoplasty astigmatism...

  7. Efficacy of senile cataract with corneal astigmatism treated with toric intraocular lens implantation

    Directory of Open Access Journals (Sweden)

    Yun-Fang Liu

    2015-10-01

    Full Text Available AIM: To discuss the efficacy of senile cataract with corneal astigmatism treated with Acrysof toric intraocular lens(IOLimplantation. to observe the clinical preoperative and postoperative visual function of Acrysof toric IOL implantation.METHODS: In this is a retrospective observational study, 34 senile(39 eyescataract patients with corneal astigmatism underwent phacoemulsification combined with Acrysof toric IOL implantation. The preoperative and 3mo postoperative uncorrected visual acuity(UCVA, best corrected visual acuity(BCVA, postoperative residual astigmatism, toric lens axis, and spectacle independence were detected and compared.RESULTS: Thirty-four patients(39 eyesunderwent phacoemulsification combined with Acrysof toric IOL implantation successfully. Preoperative UCVA was 0.15±0.06, 3mo postoperative UCVA increased to 0.65±0.15(PPPCONCLUSION: Implantation of Acrysof totic IOL for correcting astigmatism is effective, the IOL has good rotation stability, and provides postoperative visual function.

  8. Office-based relaxing incision procedure for correction of astigmatism after deep anterior lamellar keratoplasty

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Javadi

    2017-01-01

    Conclusion: Office-based relaxing incision is a safe and effective procedure for the treatment of corneal graft astigmatism after DALK. This approach effectively decreases the need for the more costly alternative in the operating room.

  9. Induced astigmatism in a 6.0 mm no-stitch frown incision.

    Science.gov (United States)

    Sinskey, R M; Stoppel, J O

    1994-07-01

    Fifty-five consecutive patients had cataract extraction with a 6 mm no-stitch frown incision and implantation of a 6 mm optic three-piece posterior chamber lens. Vector analysis calculations of diopters (D) of mean induced keratometric astigmatism for this incision were 0.70 D at one day, 0.76 D at one week, 0.50 D at one month, and 0.50 D at three months. The Naeser's polar value showed a mean with-the-rule astigmatism of +0.42 D at one day and -0.08 D against-the-rule astigmatism at three months. The results suggest that the 6.0 mm no-stitch frown incision induces a low postoperative astigmatism and provides a stable incision.

  10. Calculations of actual corneal astigmatism using total corneal refractive power before and after myopic keratorefractive surgery.

    Science.gov (United States)

    Seo, Kyoung Yul; Yang, Hun; Kim, Wook Kyum; Nam, Sang Min

    2017-01-01

    To calculate actual corneal astigmatism using the total corneal refractive astigmatism for the 4-mm apex zone of the Pentacam (TCRP4astig) and keratometric astigmatism (Kastig) before and after photorefractive keratectomy or laser in situ keratomileusis. Uncomplicated 56 eyes after more than 6 months from the surgery were recruited by chart review. Various corneal astigmatisms were measured using the Pentacam and autokeratometer before and after surgery. Three eyes were excluded and 53 eyes of 38 subjects with with-the-rule astigmatism (WTR) were finally included. The astigmatisms were investigated using polar value analysis. When TCRP4astig was set as an actual astigmatism, the efficacy of arithmetic or coefficient adjustment of Kastig was evaluated using bivariate analysis. The difference between the simulated keratometer astigmatism of the Pentacam (SimKastig) and Kastig was strongly correlated with the difference between TCRP4astig and Kastig. TCRP4astig was different from Kastig in magnitude rather than meridian before and after surgery; the preoperative difference was due to the posterior cornea only; however, the postoperative difference was observed in both anterior and posterior parts. For arithmetic adjustment, 0.28 D and 0.27 D were subtracted from the preoperative and postoperative magnitudes of Kastig, respectively. For coefficient adjustment, the preoperative and postoperative magnitudes of Kastig were multiplied by 0.80 and 0.66, respectively. By arithmetic or coefficient adjustment, the difference between TCRP4astig and adjusted Kastig would be less than 0.75 D in magnitude for 95% of cases. Kastig was successfully adjusted to TCPR4astig before and after myopic keratorefractive surgery in cases of WTR. For use of TCRP4astig directly, SimKastig and Kastig should be matched.

  11. Calculations of actual corneal astigmatism using total corneal refractive power before and after myopic keratorefractive surgery.

    Directory of Open Access Journals (Sweden)

    Kyoung Yul Seo

    Full Text Available To calculate actual corneal astigmatism using the total corneal refractive astigmatism for the 4-mm apex zone of the Pentacam (TCRP4astig and keratometric astigmatism (Kastig before and after photorefractive keratectomy or laser in situ keratomileusis.Uncomplicated 56 eyes after more than 6 months from the surgery were recruited by chart review. Various corneal astigmatisms were measured using the Pentacam and autokeratometer before and after surgery. Three eyes were excluded and 53 eyes of 38 subjects with with-the-rule astigmatism (WTR were finally included. The astigmatisms were investigated using polar value analysis. When TCRP4astig was set as an actual astigmatism, the efficacy of arithmetic or coefficient adjustment of Kastig was evaluated using bivariate analysis.The difference between the simulated keratometer astigmatism of the Pentacam (SimKastig and Kastig was strongly correlated with the difference between TCRP4astig and Kastig. TCRP4astig was different from Kastig in magnitude rather than meridian before and after surgery; the preoperative difference was due to the posterior cornea only; however, the postoperative difference was observed in both anterior and posterior parts. For arithmetic adjustment, 0.28 D and 0.27 D were subtracted from the preoperative and postoperative magnitudes of Kastig, respectively. For coefficient adjustment, the preoperative and postoperative magnitudes of Kastig were multiplied by 0.80 and 0.66, respectively. By arithmetic or coefficient adjustment, the difference between TCRP4astig and adjusted Kastig would be less than 0.75 D in magnitude for 95% of cases.Kastig was successfully adjusted to TCPR4astig before and after myopic keratorefractive surgery in cases of WTR. For use of TCRP4astig directly, SimKastig and Kastig should be matched.

  12. Application of the fractional Fourier transformation to digital holography recorded by an elliptical, astigmatic Gaussian beam.

    Science.gov (United States)

    Nicolas, F; Coëtmellec, S; Brunel, M; Allano, D; Lebrun, D; Janssen, A J E M

    2005-11-01

    The authors have studied the diffraction pattern produced by a particle field illuminated by an elliptic and astigmatic Gaussian beam. They demonstrate that the bidimensional fractional Fourier transformation is a mathematically suitable tool to analyse the diffraction pattern generated not only by a collimated plane wave [J. Opt. Soc. Am A 19, 1537 (2002)], but also by an elliptic and astigmatic Gaussian beam when two different fractional orders are considered. Simulations and experimental results are presented.

  13. Changes in Anterior, Posterior, and Total Corneal Astigmatism after Descemet Membrane Endothelial Keratoplasty

    OpenAIRE

    Maged Alnawaiseh; Lars Zumhagen; André Rosentreter; Nicole Eter

    2017-01-01

    Purpose. To evaluate changes in anterior, posterior, and total corneal astigmatism in patients after Descemet membrane endothelial keratoplasty (DMEK). Methods. We retrospectively included 29 eyes of 23 patients (age 67.6???9.8 years, 13 female, 10 male) after DMEK surgery. The magnitude and axis orientation of anterior, posterior, and total corneal astigmatism before and after DMEK were determined using a rotating Scheimpflug system (Pentacam HR, Oculus). Results. The magnitude of anterior, ...

  14. [Finite element analysis of astigmatic keratotomy based on corneal biomechanical properties].

    Science.gov (United States)

    Li, Z D; Bao, F J; Wang, Q M; Huang, J H

    2016-09-11

    To establish a finite-element biomechanical model of astigmatic keratotomy, and to investigate the impact of surgical parameters on corneal deformation, stress distribution and astigmatism correction. With Rhinoceros modeling and Abaqus finite element analysis software, a three-dimensional finite-element model of astigmatic cornea was developed, and surgical parameters such as incision optical zone, incision depth and length were varied. Postoperative corneal stress, apical deformation and astigmatism correction were assessed. A significant increase of stress was noticed near corneal incisions, and maximum corneal stress decreased with the increase of incision depth. Both anterior and posterior corneal surface moved slightly forward postoperatively. Maximum corneal stress was 340 392, 361 022 and 214 187 Pa, and anterior and posterior apical deformation was 49.80, 51.64, 55.53 μm and 54.15, 55.91, 59.67 μm, with 45°, 60° and 90° in arc length of the incision, respectively. The refractive power decreased in steep meridian and increased in flat meridian, resulting in a total decrease of corneal astigmatism. The magnitude of astigmatism correction was 0.85, 1.59, 2.23 and 3.06 D with 30°, 45°, 60° and 90° in arc length of the incision, respectively. The finite-element biomechanical model of astigmatic keratotomy could be used to predict the optical outcomes after surgery. The magnitude of astigmatism correction is positively correlated with the surgical incision arc length. (Chin J Ophthalmol, 2016, 52: 674-680).

  15. Relationship between the axis and degree of high astigmatism and obliquity of palpebral fissure.

    Science.gov (United States)

    Garcia, M Lourdes; Huang, David; Crowe, Sue; Traboulsi, Elias I

    2003-02-01

    To investigate a possible relationship between the slanting of palpebral fissures and the magnitude and axis of astigmatism in children with astigmatism. Cross-sectional study at a referral center of 53 children with astigmatism of more than +1.50 D in at least 1 eye. Visual acuity testing, cycloplegic refraction, slit-lamp biomicroscopy, and ophthalmoscopy were done on every patient. Corneal topography was obtained in 40 cooperative patients. External photographs of the midface were taken in 45 children. The degree of slanting of the palpebral fissures was evaluated based on the photographs. The statistical analysis tool used was repeated measures analysis of variance. Patients in whom photographic analysis was not available were excluded from the part of the statistical analysis dealing with eyelid slant. Palpebral fissure slant (P =.013) and gender (P =.0005) were highly correlated with the obliquity of cylinder axis. There was a possible correlation between gender and eyelid slant (P =.0594), with females having slightly larger degrees of upward palpebral fissure slanting and male more downward slanting of their fissures compared to published angles in an age-matched population. We found a statistically significant correlation between the degree of total astigmatism and a larger abnormal slant (P =.0192) and between the axis and magnitude of corneal astigmatism and abnormal slant (P =.0092). Higher degrees of eyelid slant (> 8 degrees or 3.00 D) by an odds ratio of 4.17 (95% CI: 1.03, 19.95). Children with astigmatism with large degrees of slanting of their palpebral fissures are at higher risk for high astigmatism (> 3.00 D). The axis of the astigmatism is highly correlated with the slanting of the palpebral fissure.

  16. The prevalence of anisometropia aniso-astigmatism and amblyopia in neurofibromatosis type 1.

    Science.gov (United States)

    Ardagil, Aylin; Yaylali, Sevil; Erbil, Hasan; Olgun, Ali; Aslan, Zeki; Dolar, Ayse

    2009-01-01

    The purpose of this study was to document the prevalence of anisometropia, anisoastigmatism, and anisometropic amblyopia in patients with neurofibromatosis-1 (NF1) and to compare it with that in age- and sex-matched controls. Fifty patients with NF1 and 150 age- and sex-matched controls were examined in this study. Cycloplegic autorefraction was attempted on all patients 16 years old. Anisometropia was defined as absolute interocular difference of spherical equivalent more than or equal to 1 D. Aniso-astigmatism was defined as interocular difference of refractive astigmatism of more than or equal to 1 D. Amblyopia was defined as two-line decrease in Snellen acuity between the two eyes. The overall prevalence of anisometropia, aniso-astigmatism, and amblyopia in patients with NF1 was 16%, 20%, and 10%, respectively, and they were all significantly higher than in the controls. The amblyopia was either moderate or severe in nature and all affected patients had significant astigmatism (>2.5 D) in the amblyopic eye. NF1 is a risk factor for anisometropia, aniso-astigmatism, and aniso-astigmatic amblyopia and screening patients with NF1 for refractive errors before age 3 will help to detect patients at risk of amblyopia and give them proper treatment.

  17. Sequential selective same-day suture removal in the management of post-keratoplasty astigmatism.

    Science.gov (United States)

    Fares, U; Mokashi, A A; Elalfy, M S; Dua, H S

    2013-09-01

    In a previous study, we proposed that corneal topography performed 30-40 min after the initial suture removal can identify the next set of sutures requiring removal, for the treatment of post-keratoplasty astigmatism. The aim of this study was to evaluate the effect of removing subsequent sets of sutures at the same sitting. 10/0 nylon interrupted sutures were placed, to secure the graft-host junction, at the time of keratoplasty. Topography was performed using Pentacam (Oculus) before suture removal. The sutures to be removed in the steep semi-meridians were identified and removed at the slit-lamp biomicroscope. Topography was repeated 30-40 min post suture removal, the new steep semi-meridians determined, and the next set of sutures to be removed were identified and removed accordingly. Topography was repeated 4-6 weeks later and the magnitude of topographic astigmatism was recorded. A paired-samples t-test was used to evaluate the impact of selective suture removal on reducing the magnitude of topographic and refractive astigmatism. Twenty eyes of 20 patients underwent sequential selective same-day suture removal (SSSS) after corneal transplantation. This study showed that the topographic astigmatism decreased by about 46.7% (3.68 D) and the refractive astigmatism decreased by about 37.7% (2.61 D) following SSSS. Vector calculations also show a significant reduction of both topographic and refractive astigmatism (Pkeratoplasty.

  18. Conductive keratoplasty for the treatment of astigmatism induced by corneal trauma or incision.

    Science.gov (United States)

    Xu, Wen; Ye, Panpan; Yao, Ke; Ma, Jin; Xu, Hesheng

    2010-01-01

    To assess the efficacy, safety, and predictability of conductive keratoplasty for the treatment of corneal trauma/incision-induced hyperopic or compound astigmatism. Thirteen eyes with corneal trauma/incision-induced astigmatism underwent conductive keratoplasty in this prospective study. The main outcome measures included distance uncorrected visual acuity (UCVA), near UCVA, best spectacle-corrected visual acuity (BSCVA), manifest refraction cylinder, keratometric astigmatism, manifest refraction spherical equivalent (MRSE), contrast sensitivity, glare sensitivity, intraocular pressure, tear break-up time, endothelial cell count, and pachymetry. Patients were followed 1 week and 1, 3, and 6 months postoperatively. Mean logMAR scores for distance UCVA, near UCVA, and BSCVA significantly improved from 0.87+/-0.31, 1.32+/-0.41, and 0.18+/-0.18, respectively, to 0.32+/-0.21, 0.59+/-0.21, and 0.08+/-0.11 (Pkeratoplasty. Mean manifest refraction cylinder, keratometric astigmatism, and MRSE significantly reduced from 4.12+/-2.86 diopters (D), 4.15+/-2.40 D, and 0.73+/-2.56 D, respectively, to 1.46+/-1.35 D, 1.66+/-1.44 D, and -0.52+/-0.99 D (Pastigmatism calculated by vector analysis highly correlated to target induced astigmatism (Pkeratoplasty is an effective and safe treatment for hyperopic or compound astigmatism after corneal trauma or incision. Copyright 2010, SLACK Incorporated.

  19. Correction of High Astigmatism after Penetrating Keratoplasty with Toric Multifocal Intraocular Lens Implantation

    Directory of Open Access Journals (Sweden)

    Raffaele Nuzzi

    2017-07-01

    Full Text Available After penetrating keratoplasty (PK, high astigmatism is often induced, being frequently about 4–6 dpt. According to the entity and typology of astigmatism, different methods of correction can be used. Selective suture removal, relaxing incisions, wedge resections, compression sutures, photorefractive keratectomy, and laser-assisted in situ keratomileusis can reduce corneal astigmatism and ametropia, but meanwhile they can cause a reduction in the corneal integrity and cause an over- or undercorrection. In case of moderate-to-high regular astigmatisms, the authors propose a toric multifocal intraocular lens (IOL implantation to preserve the corneal integrity (especially in PK after herpetic corneal leukoma keratitis. We evaluated a 45-year-old patient who at the age of 30 was subjected to PK in his left eye due to corneal leukoma herpetic keratitis, which led to high astigmatism (7.50 dpt cyl. 5°. The patient was subjected to phacoemulsification and customized toric multifocal IOL implantation in his left eye. The correction of PK-induced residual astigmatism with a toric IOL implantation is an excellent choice but has to be evaluated in relation to patient age, corneal integrity, longevity graft, and surgical risk. It seems to be a well-tolerated therapeutic choice and with good results.

  20. Change in astigmatism after temporal clear corneal cataract extraction in the pediatric population.

    Science.gov (United States)

    Lam, Helene Y; Yen, Kimberly G

    2008-03-18

    To evaluate the early postoperative change in astigmatism in pediatric patients having cataract extraction with intraocular lens implantation using sutured temporal clear corneal incision. A retrospective chart review was performed on all pediatric patients who underwent clear corneal cataract surgery with intraocular lens implantation between 12/01/2005 and 11/30/2006. A total of 31 eyes of 22 patients who underwent temporal clear corneal cataract surgery and intraocular lens implantation were included. The mean patient age at surgery was 6.05 years (range 1.5 months to 17 years). Mean postoperative refractive astigmatism the first day after surgery was 2.35±1.37 diopters (D). There was a statistically significant decrease in mean postoperative astigmatism by postoperative week 1 to 1.45 ± 0.79 D. Mean astigmatism was 1.48 ± 0.98 D by postoperative months 2-4, which was not a statistically significant change from postoperative day 1. Postoperative astigmatism can be expected after sutured temporal clear corneal surgery in pediatric patients and decreases over time without removal of sutures. The amount of postoperative astigmatism in children requires close follow-up after pediatric cataract surgery.

  1. Astigmatism Correction With Toric Intraocular Lenses in Descemet Membrane Endothelial Keratoplasty Triple Procedures.

    Science.gov (United States)

    Yokogawa, Hideaki; Sanchez, P James; Mayko, Zachary M; Straiko, Michael D; Terry, Mark A

    2017-03-01

    To report the clinical efficacy of astigmatism correction with toric intraocular lenses (IOLs) in patients undergoing the Descemet membrane endothelial keratoplasty (DMEK) triple procedure and to evaluate the accuracy of the correction. Fifteen eyes of 10 patients who received cataract extraction, toric IOL placement, and DMEK surgery for Fuchs corneal dystrophy and cataracts were evaluated. The cylinder power of toric IOLs was determined by an online toric calculator with keratoscopy measurements obtained using Scheimpflug corneal imaging. Prediction errors were assessed as a difference vector between the anticipated minus postoperative residual astigmatism. At 10.1 ± 4.9 months postoperatively, 8/13 (61.5%) of eyes achieved uncorrected distance visual acuity better than 20/40. Mean best spectacle-corrected distance visual acuity (logMAR) improved from 0.21 ± 0.15 preoperatively to 0.08 ± 0.12 postoperatively (P rotational misalignment by 43 degrees, we found no improvement of astigmatism. The prediction error of astigmatism at the corneal plane was 0.77 ± 0.54 D (range 0.10-1.77 D). Four eyes with preoperative "with-the-rule" corneal astigmatism had postoperative "against-the-rule" refractive astigmatism. For patients with Fuchs corneal dystrophy and cataracts, use of toric IOLs might be a valuable option in triple DMEK surgery. Additionally, care should be taken to prevent excessive IOL rotation.

  2. Intrastromal corneal ring segment implantation by femtosecond laser for the correction of residual astigmatism after penetrating keratoplasty.

    Science.gov (United States)

    Prazeres, Tatiana Moura Bastos; Souza, Allan Cezar da Luz; Pereira, Nicolas Cesário; Ursulino, Fábio; Grupenmacher, Leon; de Souza, Luciene Barbosa

    2011-12-01

    To evaluate the safety and efficacy of intracorneal ring segments (ICRSs) aided by femtosecond (FS) laser for the correction of residual astigmatism after penetrating keratoplasty (PKP). This retrospective noncomparative study comprised 14 eyes of 14 patients with high astigmatism after PKP who had ICRS implantation by femtosecond laser. The study evaluated uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive astigmatism, and corneal maximum curvature. The CDVA postoperatively improved after 3 months (P 0.999) as well as the UDVA (P = 0.276). The preoperative astigmatism was higher than that after surgery (P = 0.001). The preoperative maximum curvature was higher than that of the postoperative maximum curvature (P astigmatism post-PKP was safe and showed satisfactory results. It reduced refractive astigmatism and maximum corneal curvature and improved UDVA and CDVA.

  3. Effects of chalazia on corneal astigmatism : Large-sized chalazia in middle upper eyelids compress the cornea and induce the corneal astigmatism.

    Science.gov (United States)

    Jin, Ki Won; Shin, Young Joo; Hyon, Joon Young

    2017-03-31

    A chalazion is a common eyelid disease that causes eye morbidity due to inflammation and cosmetic disfigurement. Corneal topographic changes are important factors in corneal refractive surgery, intraocular lens power calculations for cataract surgery, and visual acuity assessments. However, the effects of chalazia on corneal astigmatism have not been thoroughly investigated. The changes in corneal astigmatism according to chalazion size and location is necessary for better outcome of ocular surgery. The aim of this study is to evaluate changes in corneal astigmatism according to chalazion size and location. In this cross-sectional study, a total of 44 eyes from 33 patients were included in the chalazion group and 70 eyes from 46 patients comprised the control group. Chalazia were classified according to location and size. An autokeratorefractometer (KR8100, Topcon; Japan) and a Galilei™ dual-Scheimpflug analyzer (Ziemer Group; Port, Switzerland) were utilized to evaluate corneal changes. Oblique astigmatism was greater in the chalazion group compared with the control group (p chalazion group (p chalazion group, whole area group, and large-sized chalazion group (p Chalazion should be treated before corneal topography is performed preoperatively and before the diagnosis of corneal diseases.

  4. Effect of corneal biomechanical properties on surgically-induced astigmatism and higher-order aberrations after cataract surgery

    National Research Council Canada - National Science Library

    Koç, Mustafa; İlhan, Çağrı; Koban, Yaran; Özülken, Kemal; Durukan, İrfan; Yılmazbaş, Pelin

    2016-01-01

    ABSTRACT Purpose: To investigate the relationship between biomechanical properties of the cornea and postoperative refractive changes in patients with low-level astigmatism after cataract surgery. Methods...

  5. Corneal Astigmatism Stability in Descemet Membrane Endothelial Keratoplasty for Fuchs Corneal Dystrophy.

    Science.gov (United States)

    Yokogawa, Hideaki; Sanchez, P James; Mayko, Zachary M; Straiko, Michael D; Terry, Mark A

    2016-07-01

    To calculate the magnitude and angle of the shift in corneal astigmatism associated with Descemet membrane endothelial keratoplasty (DMEK) surgery to determine the feasibility of concurrent astigmatism correction at the time of DMEK triple procedures. Retrospective study. Forty-seven eyes that previously underwent the DMEK procedure for Fuchs endothelial corneal dystrophy and that had more than 1.0 diopter (D) of front corneal astigmatism preoperatively were identified. All DMEK surgeries used a clear corneal temporal incision of 3.2 mm. Surgically induced astigmatism (SIA) was evaluated 6 months postsurgery with vector analysis using Scheimpflug image reading. We did not find a difference between pre- and postoperative magnitude of front astigmatism (P = 0.88; paired t test). The magnitude of the SIA front surface was 0.77 ± 0.63 D (range, 0.10-3.14 D). The centroid vector of the SIA front surface was 0.14 at 89.3°. A hyperopic corneal power shift was noted in both the front surface by 0.26 ± 0.74 D (range, 0.45-3.05 D) (P = 0.018; paired t test) and back surface by 0.56 ± 0.55 D (range, 0.25-2.40 D) (P astigmatism that is a with-the-rule shift associated with a temporal clear corneal incision. The stability of these data from preop to postop supports the plausibility of incorporating astigmatism correction with the cautious use of toric intraocular lenses for patients with Fuchs corneal dystrophy and cataract.

  6. Implantation of a customized toric intraocular lens for correction of post-keratoplasty astigmatism.

    Science.gov (United States)

    Srinivasan, S; Ting, D S J; Lyall, D A M

    2013-04-01

    To report visual and refractive outcomes, and endothelial cell loss following primary and secondary 'piggyback' toric intraocular lens (IOL) implantation in patients with high post-penetrating keratoplasty (PK) astigmatism. Prospective case series. Nine eyes of nine patients with post-PK astigmatism were consecutively recruited for implantation of a customized toric IOL. Six underwent simultaneous phacoemulsification (PE) and three pseudophakic eyes had a secondary 'piggyback' toric IOL implanted in the ciliary sulcus. Mean follow-up time was 17.2±7.7 months. Pre- and post-operative uncorrected (UDVA) and best-corrected (BDVA) distance visual acuities and refractive errors were collected for comparison. Cartesian astigmatic vectors were calculated to identify a change in the magnitude of astigmatism pre- compared to postoperatively. Pre- and post-operative endothelial cell counts were also collected for analysis. UDVA (logMAR) improved from 1.13±0.51 preoperatively to 0.48±0.24 postoperatively (P-value=0.003). There was no significant change in BDVA (P-value=0.905) from 0.31±0.27 to 0.26±0.19. Corneal astigmatism preoperatively was 6.57±4.40 diopters (D). Post-operative refractive cylinder was 0.83±1.09 D compared to 3.89±4.01 D preoperatively (P=0.039). Analysis of astigmatic Cartesian x and y coordinates found a significant reduction postoperatively compared to preoperatively (P=0.005 and P=0.002), respectively. Mean endothelial cell loss was 9.9%. Implantation of a customized primary or secondary 'piggyback' toric IOL serves as an effective modality in treating patients with high post-PK astigmatism.

  7. Effect of pupil size on uncorrected visual acuity in astigmatic eyes.

    Science.gov (United States)

    Kamiya, Kazutaka; Kobashi, Hidenaga; Shimizu, Kimiya; Kawamorita, Takushi; Uozato, Hiroshi

    2012-02-01

    To determine the effects of pupil size on uncorrected visual acuity (UCVA) in astigmatic eyes. The authors examined 20 normal eyes of 20 healthy volunteers (age 26.7±4.9 years (mean±SD); 8 men, 12 women). After fully correcting cycloplegic refraction, the authors created with-the-rule and against-the-rule astigmatism of 1, 2, and 3 dioptres (D) in each eye, and then assessed UCVA using artificial pupils (1 to 5 mm) in these astigmatic eyes. Measurements were performed three times, and the mean value was used for statistical analysis. In eyes with with-the-rule astigmatism of 1, 2 and 3 D, logMAR UCVA was 0.04±0.08, 0.09±0.09 and 0.16±0.16 for 1 mm pupils, -0.01±0.09, 0.12±0.15 and 0.33±0.24 for 2 mm pupils, 0.02±0.09, 0.20±0.19 and 0.46±0.30 for 3 mm pupils, 0.02±0.08, 0.24±0.20 and 0.48±0.21 for 4 mm pupils, and 0.08±0.10, 0.33±0.18 and 0.53±0.22 for 5 mm pupils, respectively. The variance of the data was statistically significant (p=0.03 for 1 D, ppupil size can affect UCVA in astigmatic eyes. It is suggested that not only the amount of astigmatism but also the pupil size should be taken into consideration for acquiring better visual performance in astigmatic eyes.

  8. Changes in falling risk depending on induced axis directions of astigmatism on static posture.

    Science.gov (United States)

    Kim, Sang-Yeob; Moon, Byeong-Yeon; Cho, Hyun Gug

    2015-06-01

    [Purpose] To assess the changes in falling risk depending on the induced axis direction of astigmatism using cylindrical lenses in a static posture. [Subjects and Methods] Twenty subjects (10 males, 10 females; mean age, 23.4 ± 2.70 years) fully corrected by subjective refraction participated. To induce myopic simple astigmatism conditions, cylindrical lenses of +0.50, +1.00, +1.50, +2.00, +3.00, +4.00, and +5.00 D were used. The direction of astigmatic axes were induced under five conditions with increased cylindrical powers:, 180°, 90°, and 45° on both eyes; 180°/90° right/left eye, and 45°/135° right/left eye. Changes in the fall risk index were analyzed using the TETRAX biofeedback system. Measurements were performed for 32 seconds for each condition. [Results] The fall risk index increased significantly from C+4.00 D in 180°/90° right/left eye, C+3.00 D in 45°/135° right/left eye, and C+3.00 D in 45° on both eyes versus corrected emmetropia. Among the five axis conditions with the same cylindrical power lenses, the increase in the fall risk index was highest at 45° in both eyes. [Conclusion] Uncorrected oblique astigmatism may increase falling risk compared to with-the-rule and against-the-rule astigmatism. Clinical specialists should consider appropriate correction of astigmatism for preventing falls, especially for uncorrected oblique astigmatism.

  9. Toric phakic intraocular lens for the correction of hyperopia and astigmatism.

    Science.gov (United States)

    Bartels, Marjolijn C; Santana, Nathalie T Y; Budo, Camille; van Rij, Gabriel; Mulder, Paul G H; Luyten, Gregorius P M

    2006-02-01

    To evaluate the Artisan toric phakic intraocular lens (pIOL) for the correction of hyperopia and astigmatism. Department of Ophthalmology, Erasmus MC, Rotterdam, The Netherlands, and Department of Ophthalmology, Sint Truiden, Belgium. In this prospective study of 47 eyes of 28 patients with hyperopia and astigmatism, Artisan toric pIOLs were implanted between April 1999 and June 2004. Uncorrected visual acuity (UCVA), best corrected visual acuity, refraction, astigmatism, safety, and predictability were analyzed. Change in astigmatism was analyzed with vector analysis. Refractive cylinders are expressed in minus form. Mean preoperative spherical equivalent was +4.33 diopters (D) +/- 2.26 (SD). Mean follow-up was 11.1 months (range 6 to 36 months). A gain of 1 or more lines in best spectacle-corrected visual acuity (BSCVA) was seen in 36.2%. Safety index and efficacy index after 6 months were 1.06 and 0.87, respectively. The mean postoperative astigmatism at 6 months was 0.19 D at an axis of 144 degrees. At 6 months, about three quarters (76.6%) of the eyes had a UCVA of 20/40 or better. One eye lost 2 lines of BSCVA. In 1 eye, the lens position had to be changed because of a large axis misalignment. No serious complications developed in any of the treated eyes during follow-up. Artisan toric pIOLs can correct moderate to high hyperopia combined with astigmatism with good refractive results. In this study, there were no serious complications. However, the predictability of the refractive results appeared to be lower than those in the correction of myopia and astigmatism with toric Artisan lenses.

  10. On the calibration of astigmatism particle tracking velocimetry for microflows

    Science.gov (United States)

    Cierpka, C.; Rossi, M.; Segura, R.; Kähler, C. J.

    2011-01-01

    Astigmatism particle tracking velocimetry (APTV) is a method to determine three components (3C) of the velocity field in a volume (3D) using a single camera. The depth position of the particles is coded by optical distortions caused by a cylindrical lens in the optical setup. This technique is particularly suited for microfluidic applications as measurement errors due to spatial averaging and depth of correlation, typically encountered with μPIV approaches, are eliminated so that the measurement precision is enhanced. Unfortunately, the current state of the technique is limited by the small measurement region achievable with the current calibration procedures as well as by higher order image aberrations (Cierpka et al 2010 Meas. Sci. Technol. 21 045401). In order to extend the size of the measurement volume and to account for all image aberrations, a new intrinsic calibration procedure, based on the imaging function of the particles, is proposed in the paper at hand. It provides an extended measurement depth, taking into account all image aberrations. In this work, the calibration procedure was applied to a μPIV arrangement but could also be implemented on macroscopic experimental setups. The calibration procedure is qualified with synthetic data as well as Poiseuille flow in a straight rectangular micro-channel with a cross-sectional area of 200 × 500 µm2. The three-dimensional velocity distribution of the whole channel was resolved via APTV with uncertainties of 0.9% and 3.7% of the centerline velocity, uc, for the in-plane and out-of-plane components, respectively. Further investigations using different cylindrical-lens focal lengths, magnifications and particle sizes provide information about achievable measurement depths and help to design and adapt the optimal system for the desired experiment.

  11. Analysis of cataract surgery induced astigmatism: Two polar methods comparison.

    Science.gov (United States)

    García-López, Veronica; García-López, Claudia; de Juan, Victoria; Martin, Raul

    Surgically induced astigmatism (SIA) caused by the incision after cataract surgery may be calculated to improve IOL toric power calculation and achieve better visual outcome. SIA could be determined as the difference between preoperative and postoperative keratometry expressed in polar values using different equations. The objective of this study is to compare the SIA calculated with two different polar value analysis methods [Method #1: KP (90)/KP (135) developed to be used with incisions placed at 90° and Method #2: AKP/AKP (+45) developed to be used independently of the incision location]. Preoperative and one month postoperative data of 210 cataractous eyes (131 patients) undergoing uncomplicated cataract surgery were assessed. All incisions were performed at 11 o'clock (120°). No sutures were used in any patient. IOLMaster (Carl Zeiss Meditec, Dublin, Ireland) keratometry was used to polar calculation. The average age was 66.25±12.33 years (range 22-89). SIA polar value data calculated with Method #1 were KP (90) -0.06±0.52D and KP (135) +0.05±0.91D and calculated with Method #2 were AKP -0.10±0.87D and AKP (+45) +0.02±0.02D. However, SIA value represented in traditional notation (diopters@axis in degrees) was the same value independently of the method used to calculate; +0.65@110.70°. SIA value is independent of the polar method used to its calculation and slight variations in the incision position could be accepted without clinical relevant impact in SIA magnitude. Both methods [Method #1: KP (90)/KP (135) and Method #2: AKP/AKP (+45)] are useful to calculate SIA with superior incisions at 120°. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

  12. Convergence Insufficiency, Accommodative Insufficiency, Visual Symptoms, and Astigmatism in Tohono O’odham Students

    Directory of Open Access Journals (Sweden)

    Amy L. Davis

    2016-01-01

    Full Text Available Purpose. To determine rate of convergence insufficiency (CI and accommodative insufficiency (AI and assess the relation between CI, AI, visual symptoms, and astigmatism in school-age children. Methods. 3rd–8th-grade students completed the Convergence Insufficiency Symptom Survey (CISS and binocular vision testing with correction if prescribed. Students were categorized by astigmatism magnitude (no/low: <1.00 D, moderate: 1.00 D to <3.00 D, and high: ≥3.00 D, presence/absence of clinical signs of CI and AI, and presence of symptoms. Analyses determine rate of clinical CI and AI and symptomatic CI and AI and assessed the relation between CI, AI, visual symptoms, and astigmatism. Results. In the sample of 484 students (11.67 ± 1.81 years of age, rate of symptomatic CI was 6.2% and symptomatic AI 18.2%. AI was more common in students with CI than without CI. Students with AI only (p=0.02 and with CI and AI (p=0.001 had higher symptom scores than students with neither CI nor AI. Moderate and high astigmats were not at increased risk for CI or AI. Conclusions. With-the-rule astigmats are not at increased risk for CI or AI. High comorbidity rates of CI and AI and higher symptoms scores with AI suggest that research is needed to determine symptomatology specific to CI.

  13. Influence of corneal astigmatism, corneal curvature and meridional differences on corneal hysteresis and corneal resistance factor.

    Science.gov (United States)

    Wong, Yin-zhi; Lam, Andrew K C

    2011-09-01

    This study investigated the influence of corneal astigmatism, corneal curvature and meridional differences on corneal hysteresis (CH) and the corneal resistance factor (CRF) in a group of normal Chinese persons. Ninety-five participants were recruited and data from the eye with higher corneal astigmatism were analysed. The anterior corneal curvature was measured by corneal topography. The Goldmann-correlated intraocular pressure (IOPg), corneal-compensated intraocular pressure (IOPcc), CH and CRF at different meridians (default horizontal position, 10°, 20° and 30° along the superotemporal and inferonasal meridians) were obtained from an ocular response analyser. The corneal powers at these specific meridians also were calculated. At the default position, the IOPg and CRF had weak correlations with corneal astigmatism, while the IOPcc and CH were not significantly correlated with corneal astigmatism. Both the IOPg and IOPcc were measured significantly higher at the default position. The CH and CRF were lower at the default position but the difference in the CRF from obliquity could not reach statistical significance. The CH was not significantly correlated with the corneal power at all meridians. The CRF correlated with the corneal power only at 30° superotemporal. Corneal astigmatism and head tilt did not have much effect on the measurement of CH and the CRF, both of which were lowest along the horizontal meridian. Clinically, the difference was small. The influence of corneal power on CH and the CRF was minimal. © 2011 The Authors. Clinical and Experimental Optometry © 2011 Optometrists Association Australia.

  14. Non-toric extended depth of focus contact lenses for astigmatism and presbyopia correction

    Science.gov (United States)

    Ben Yaish, Shai; Zlotnik, Alex; Yehezkel, Oren; Lahav-Yacouel, Karen; Belkin, Michael; Zalevsky, Zeev

    2010-02-01

    Purpose: Testing whether the extended depth of focus technology embedded on non-toric contact lenses is a suitable treatment for both astigmatism and presbyopia. Methods: The extended depth of focus pattern consisting of microndepth concentric grooves was engraved on a surface of a mono-focal soft contact lens. These grooves create an interference pattern extending the focus from a point to a length of about 1mm providing a 3.00D extension in the depth of focus. The extension in the depth of focus provides high quality focused imaging capabilities from near through intermediate and up to far ranges. Due to the angular symmetry of the engraved pattern the extension in the depth of focus can also resolve regular as well as irregular astigmatism aberrations. Results: The contact lens was tested on a group of 8 astigmatic and 13 subjects with presbyopia. Average correction of 0.70D for astigmatism and 1.50D for presbyopia was demonstrated. Conclusions: The extended depth of focus technology in a non-toric contact lens corrects simultaneously astigmatism and presbyopia. The proposed solution is based upon interference rather than diffraction effects and thus it is characterized by high energetic efficiency to the retina plane as well as reduced chromatic aberrations.

  15. Preoperative corneal astigmatism among adult patients with cataract in Northern Nigeria

    Directory of Open Access Journals (Sweden)

    Mohammed Isyaku

    2014-01-01

    Full Text Available The prevalence and nature of corneal astigmatism among patients with cataract has not been well-documented in the resident African population. This retrospective study was undertaken to investigate preexisting corneal astigmatism in adult patients with cataract. We analyzed keratometric readings acquired by manual Javal-Schiotz keratometry before surgery between January 1, 2011 and December 31, 2011. There were 3,169 patients (3286 eyes aged between 16 and 110 years involved with a Male to female ratio of 1.4:1. Mean keratometry in diopters was K1 = 43.99 and K2 = 43.80. Mean corneal astigmatism was 1.16 diopter and a majority (45.92% of eyes had astigmatism between 1.00 and 1.99 diopters. Two-thirds of the eyes (66.9% in this study had preoperative corneal astigmatism equal to or above 1.00 diopter. Findings will help local cataract surgeons to estimate the potential demand for toric intraocular lenses.

  16. Assessment of refractive astigmatism and simulated therapeutic refractive surgery strategies in coma-like-aberrations-dominant corneal optics.

    Science.gov (United States)

    Zhou, Wen; Stojanovic, Aleksandar; Utheim, Tor Paaske

    2016-01-01

    The aim of the study is to raise the awareness of the influence of coma-like higher-order aberrations (HOAs) on power and orientation of refractive astigmatism (RA) and to explore how to account for that influence in the planning of topography-guided refractive surgery in eyes with coma-like-aberrations-dominant corneal optics. Eleven eyes with coma-like-aberrations-dominant corneal optics and with low lenticular astigmatism (LA) were selected for astigmatism analysis and for treatment simulations with topography-guided custom ablation. Vector analysis was used to evaluate the contribution of coma-like corneal HOAs to RA. Two different strategies were used for simulated treatments aiming to regularize irregular corneal optics: With both strategies correction of anterior corneal surface irregularities (corneal HOAs) were intended. Correction of total corneal astigmatism (TCA) and RA was intended as well with strategies 1 and 2, respectively. Axis of discrepant astigmatism (RA minus TCA minus LA) correlated strongly with axis of coma. Vertical coma influenced RA by canceling the effect of the with-the-rule astigmatism and increasing the effect of the against-the-rule astigmatism. After simulated correction of anterior corneal HOAs along with TCA and RA (strategies 1 and 2), only a small amount of anterior corneal astigmatism (ACA) and no TCA remained after strategy 1, while considerable amount of ACA and TCA remained after strategy 2. Coma-like corneal aberrations seem to contribute a considerable astigmatic component to RA in eyes with coma-like-aberrations dominant corneal optics. If topography-guided ablation is programmed to correct the corneal HOAs and RA, the astigmatic component caused by the coma-like corneal HOAs will be treated twice and will result in induced astigmatism. Disregarding RA and treating TCA along with the corneal HOAs is recommended instead.

  17. Clinical efficacy of Toric intraocular lens implantation for cataract patients with corneal astigmatism

    Directory of Open Access Journals (Sweden)

    Guo-Hua Deng

    2015-11-01

    Full Text Available AIM: To investigate the clinical efficacy of Toric intraocular lens(IOLimplantation for cataract patients with corneal astigmatism.METHODS: Thirty-eight patients(46 eyeswith corneal astigmatism undergone phacoemulsification and IOL implantation in our hospital from June 2013 to July 2014 were observed. Twenty cases(24 eyesreceived Toric IOL, 18 cases(22 eyesgot Acrysof IQ IOL. The clinical efficacy of the two groups was analyzed.RESULTS:The difference on visual acuity after surgery between the two groups was statistically significant(F=5.783, PPt=5.248, 2.573, 2.782; all PF=5.482, PPt=6.591, 3.287, 2.167; all PCONCLUSION: Phacoemulsification associated with Toric IOL implantation has good correction effect and prediction for cataract and corneal astigmatism patients, and can improve the visual activity significantly, so it is worthy of clinical application.

  18. Results of a graded relaxing incision technique for post keratoplasty astigmatism.

    Science.gov (United States)

    Arffa, R C

    1988-09-01

    A technique of graded relaxing incisions and compression sutures was performed for correction of post keratoplasty astigmatism in six patients who were spectacle and contact lens intolerant. Correction was achieved in all six patients after surgery, five with spectacles and one with a contact lens. Keratometric astigmatism decreased from an average of 9.63 diopters preoperatively to 2.17 D postoperatively, a reduction of 7.46 D, or 77%. Up to 13.50 D of correction was obtained. In general, the effect of surgery progressed from 1 week to 3 months postoperatively, and regressed from 3 to 6 months. Complications included perforation in two patients, one requiring suturing and application of tissue adhesive, and graft reaction in two patients. Although the number of patients is small, it appears that this technique can successfully reduce post keratoplasty astigmatism, even in excess of 10 D.

  19. [Prevalence and age-related changes of corneal astigmatism in patients before cataract surgery].

    Science.gov (United States)

    Michelitsch, M; Ardjomand, N; Vidic, B; Wedrich, A; Steinwender, G

    2017-03-01

    The aim of this study was to determine the extent and the distribution of corneal astigmatism in patients awaiting cataract surgery in a mid-European tertiary clinic centre and hence to establish the demand for methods reducing corneal astigmatism. Keratometry measurements of cataract surgery candidates assigned to a university clinic between January 2013 and October 2014 were recorded and analysed retrospectively. A total of 6900 eyes of 3450 patients with a mean age of 72.5 ± 12.2 were analyzed. The corneal astigmatism was more than 0.5 dioptres (D) in 5193 eyes (75.3 %), >1.0 D in 2641 eyes (38.3 %), >1.5 D in 1304 eyes (18.9 %), >2.0 D in 644 eyes (9.3 %), >2.5 D in 363 eyes (5.3 %), >3.0 D in 236 eyes (3.4 %) and >3.5 D in 149 eyes (2.2 %). With increasing age a shift from with-the-rule astigmatism towards against-the-rule astigmatism was observed. Of the patients admitted for routine cataract surgery at our clinic, 2641 eyes (38.3 %) had an astigmatism greater than 1.0 D. Our data could be helpful in establishing a protocol for using toric intraocular lenses and to determine the costs.

  20. Femtosecond laser arcuate keratotomy for the correction of postkeratoplasty high astigmatism in keratoconus

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    Mohammad Naser Hashemian

    2017-01-01

    Full Text Available Background: Astigmatism is the leading complication in visual recovery after penetrating keratoplasty (PKP and deep anterior lamellar keratoplasty (DALK; in this study, we evaluated the outcome of femtosecond laser arcuate keratotomy (FLAK after DALK and PKP in Iranian keratoconic patients. Materials and Methods: In this prospective interventional case series, refractive and keratometric predictability, efficacy, and complications of FLAK for postkeratoplasty astigmatism in keratoconus were evaluated; 23 eyes of 23 consecutive patients (mean age of 32.43 ± 9.11 years with high astigmatism were enrolled. The femtosecond laser performed paired 90°-angled arcuate incisions. Results: Mean logarithm of the minimum angle of resolution of corrected and uncorrected visual acuity improved from preoperative values of 0.30 ± 0.18 and 0.85 ± 0.32 to 6-month values of 0.19 ± 0.17 and 0.65 ± 0.33, respectively (P < 0.05. Mean subjective astigmatism was 7.79 ± 2.64 diopter (D preoperatively and 3.69 ± 2.25D at 6-month after surgery (P < 0.05. Surgically induced astigmatism was 9.27 ± 5.00D. Mean refractive spherical equivalent showed no significant (P = 0.69 hyperopic shift from − 4.21 ± 4.84D preoperatively to − 2.16 ± 6.09D postoperatively. Two (8.7% microperforations were observed. Conclusion: FLAK is a relatively safe and effective method for the treatment of postkeratoplasty astigmatism.

  1. Toric intraocular lenses for correction of astigmatism in keratoconus and after corneal surgery

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    Mol IEMA

    2016-06-01

    Full Text Available Ilse EMA Mol,1,2 Bart TH Van Dooren1,2 1Department of Ophthalmology, Amphia Hospital, Breda, 2Department of Ophthalmology, Erasmus Medical Center, Rotterdam, the Netherlands Purpose: To describe the results of cataract extraction with toric intraocular lens (IOL implantation in patients with preexisting astigmatism from three corneal conditions (keratoconus, postkeratoplasty, and postpterygium surgery.Methods: Cataract patients with topographically stable, fairly regular (although sometimes very high corneal astigmatism underwent phacoemulsification with implantation of a toric IOL (Zeiss AT TORBI 709, Alcon Acrysof IQ toric SN6AT, AMO Tecnis ZCT. Postoperative astigmatism and refractive outcomes, as well as visual acuities, vector reduction, and complications were recorded for all eyes.Results: This study evaluated 17 eyes of 16 patients with a mean age of 60 years at the time of surgery. Mean follow-up in this study was 12 months. The corrected distance Snellen visual acuity (with spectacles or contact lenses 12 months postoperatively was 20/32 or better in 82% of eyes. The mean corneal astigmatism was 6.7 diopters (D preoperatively, and 1.5 D of refractive cylinder at 1-year follow-up. No vision-compromising intra- or postoperative complications occurred and decentration or off-axis alignment of toric IOLs were not observed.Conclusion: Phacoemulsification with toric IOL implantation was a safe and effective procedure in the three mentioned corneal conditions. Patient selection, counseling, and IOL placement with optimal astigmatism correction are crucial. Keywords: toric intraocular lens, phacoemulsification, corneal astigmatism, keratoconus, postkeratoplasty, postpterygium surgery

  2. Comparison of astigmatic keratotomy results in deep anterior lamellar keratoplasty and penetrating keratoplasty in keratoconus.

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    Kubaloglu, Anil; Coskun, Erol; Sari, Esin Sogutlu; Guneş, Alime Sefer; Cinar, Yasin; Piñero, David P; Kutluturk, Isil; Ozerturk, Yusuf

    2011-04-01

    To compare astigmatic keratotomy (AK) outcomes in high astigmatism after deep anterior lamellar keratoplasty (DALK) and after penetrating keratoplasty (PK) in keratoconus patients. Prospective, comparative, interventional case series. This study comprised 20 eyes that underwent DALK and 24 eyes that underwent PK. After suture removal, all eyes had more than 5 diopters (D) of astigmatism and underwent standard manual 1-pair, 90-degree, and 90% corneal thickness AK incisions. The main outcome measures included preoperative and postoperative manifest refraction, uncorrected visual acuity, best spectacle-corrected visual acuity, surgically induced astigmatism, Orbscan II (Bausch & Lomb) corneal topography results, keratometric astigmatism, and complications. All eyes completed 6 months of follow-up. The overcorrection rate was 35% and 41.6% in the DALK and PK groups, respectively (P=.75). At 6 months after AK, logarithm of the minimal angle of resolution uncorrected visual acuity improved from 0.88 ± 0.20 to 0.54 ± 0.26 and from 1.0 ± 0.34 to 0.53 ± 0.26 in the DALK and PK groups, respectively (P=.01 to Pastigmatism was 6.10 ± 3.27 D in the DALK group and 7.15 ± 2.98 D in the PK group (P=.36). The manual AK for the treatment of postkeratoplasty astigmatism after DALK and PK in keratoconus patients is a safe and effective surgical procedure, allowing similar refractive cylinder reduction and improvement in uncorrected visual acuity and best spectacle-corrected visual acuity. Copyright © 2011 Elsevier Inc. All rights reserved.

  3. Factors related to the correction of astigmatism by LASIK after penetrating keratoplasty.

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    Lee, Hyun Soo; Kim, Man Soo

    2010-12-01

    To analyze the preoperative factors related to successful correction of astigmatism by LASIK after penetrating keratoplasty (PKP). This retrospective chart review included 71 patients (75 eyes) undergoing LASIK after PKP. The full refractive cylindrical (thus near-spherical) errors were treated by laser ablation. Postoperative follow-up examinations included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest autorefraction, slit-lamp examination, topography, specular microscopy, and simple questionnaire regarding satisfaction with LASIK at 1 day, 1 week, and 1, 6, and 12 months. Before surgery, no eye had UDVA of 20/60 or better and 42 (56%) eyes had CDVA of 20/40 or better. At 1 year, 45 (60%) eyes had UDVA of 20/60 or better and 57 (76%) eyes had CDVA of 20/40 or better. The mean astigmatism was 6.80±2.10 diopters (D) preoperatively. The mean reduction of astigmatism was 3.80±2.30 D (53.9±28.7%) at 12 months after LASIK and was relatively stable between 6 and 12 months. Although mean achieved correction showed a tendency toward undercorrection, CDVA and contact lens/spectacle tolerance were significantly increased. The younger the patient, the lesser magnitude of refractive cylinder, and greater endothelial cell density showed better astigmatism reduction in the multiple regression analysis. LASIK is a safe and effective procedure with stability for reducing astigmatism following PKP and increasing spectacle or contact lens tolerance. For optimal predictability and visual outcomes after LASIK, we recommend the full identification of astigmatism after PKP and preoperative analysis of the endothelial cell density. Copyright 2010, SLACK Incorporated.

  4. Clinical research on keratoconus and subclinical keratoconus in patients with astigmatism examined by Pentacam

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    Yang An

    2016-03-01

    Full Text Available AIM: To study the keratoconus(KCNand subclinical KCN in patients with astigmatism ≥2D by Pentacam anterior segment analyzer. METHODS: Two hundred and one eyes in 107 patients with astigmatism ≥2D were included in this study. All patients underwent optometry, visual acuity, corrected visual acuity, slit lamp biomicroscopy, fundus examination, traditional corneal topography and examination with Pentacam. Changes of several parameters were observed including K1(horizontal central curvature within the scope with diameter of 3mm, K2(vertical central curvature within the scope with diameter of 3mm; Kmax(the maximum anterior corneal refractive power, corneal astigmatism(CYL, MinPachy(the thickness at the thinnest area of cornea, index of surface variation(ISV, index of vertical asymmetry(IVA, keratoconus index(KI, height of anterior corneal surface(AEand height of posterior corneal surface(PE, etc. ROC curve was made. Cutoff value and the sensitive index of each group were compared. Mann-Whitney U test was used for analysis of several parameters obtained from Pentacam. ROC curve was analyzed to determine the best diagnosis cutoff value. RESULTS: Mean age of the study population was 25.7±6.6 years old. Kmax, IVA, KI, AE and PE of the clinical and subclinical group were significantly higher than those of the astigmatism group, while the thickness at the thinnest area of cornea in clinical and subclinical group was lower than that of the astigmatism group(PCONCLUSION: The current study shows that subjects with 2D or more of astigmatism, even some of them have normal vision, should undergo corneal topography screening. Pentacam may provide more accurate information about anterior and posterior corneal anatomy especially for the height of posterior corneal surface, which plays an important role in screening of subclinical KCN.

  5. Analyses of surgically induced astigmatism and axis deviation in microcoaxial phacoemulsification.

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    Özyol, Erhan; Özyol, Pelin

    2014-06-01

    To evaluate surgically induced astigmatism (SIA) and axis deviation after coaxial microincision superotemporal clear corneal phacoemulsification incision in eyes with differently located steep axis. This prospective, comparative study included four groups of 45 eyes with age-related cataracts; each group underwent 2.2-mm superotemporal clear corneal incision (CCI) cataract surgery. The four groups of patients were divided by location of the steep axis. Groups were matched according to symmetry of the steep axis for both right and left eyes as follows--0°-45° of steep axis for right eyes, and 136°-180° for left eyes (group 1); 46°-90° for right eyes and 91°-135° for left eyes (group 2); 91°-135° for right eyes and 46°-90° for left eyes (group 3); and 136°-180° for right eyes and 0°-45° for left eyes (group 4). Outcome measures included changes in mean total astigmatism, SIA, and axis deviation. Astigmatism was measured by manual keratometry readings before surgery and week 1, week 4, week 8, and week 12 postoperatively. SIA was calculated by the vector analysis (Holladay-Cravy-Koch method). The magnitude of mean total astigmatism was lowest in group 3 and highest in group 1 at week 12. SIA was 0.39 diopters (D), 0.22 D, 0.17 D, and 0.28 D in group 1, group 2, group 3, and group 4, respectively. The change in astigmatic axis deviation was highest in group 3 (23.6 ± 16.6) (P Axis deviation and SIA were stable after week 4. Planning of CCI on or near the steep axis can help decrease corneal astigmatism.

  6. [Cataract surgery with implantation of toric silicone lenses for severe astigmatism after keratoplasty].

    Science.gov (United States)

    Buchwald, H-J; Lang, G K

    2004-06-01

    The treatment of high astigmatism after keratoplasty is often not possible with glasses or refractive corneal surgery, particularly in patients with anisometropia and contact lens incompatibility. In 3 patients with cataract and high astigmatism after penetrating keratoplasty, phacoemulsification was performed via a 4 mm sclerocorneal tunnel incision. A toric silicone lens with Z-haptic was implanted in the bag (Type MS 6116 TU, Dr. Schmidt). All patients had high anisometropia and contact lens incompatibility. The follow-up was ten weeks, uncorrected and corrected visual acuity, corneal and total astigmatism were evaluated. A 68-year-old female presented with corneal astigmatism of 10 dpt. Keratoplasty was performed two years earlier. After implantation of a toric lens (+ 22.5 + 11.0 dpt.) uncorrected visual acuity increased from 1/50 to 20/40, corrected visual acuity increased from 20/30 to 20/25. A 78-year-old male presented with irregular corneal astigmatism of 6.5 dpt. Keratoplasty was performed 25 years previously. Due to high myopia (corneal radii 5.3/5.9 mm), implantation of a toric lens (- 3.0 + 7.0 dpt.) in the bag was combined with implantation of a spheric lens (- 6.0 dpt., Type MS 614, Dr. Schmidt) in the sulcus. Uncorrected visual acuity increased from light perception to 1/20, corrected visual acuity increased to 1/10. An 84-year-old female presented with irregular corneal astigmatism of 8.6 dpt. Keratoplasty was performed two years earlier. After implantation of a toric lens (+ 16.0 + 11.0 dpt.) uncorrected visual acuity increased to 20/50, corrected visual acuity increased from 20/100 to 20/25. During the follow-up all implanted lenses were well-centered and no significant IOL rotation was observed. Implantation of foldable toric silicone lenses during cataract surgery may improve considerably the uncorrected visual acuity by reducing the total astigmatism in patients with high astigmatism after keratoplasty. Preoperatively, a reliable keratometry

  7. Toric intraocular lens orientation and residual refractive astigmatism: an analysis

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    Potvin R

    2016-09-01

    astigmatism as a result of misorientation. The Tecnis Toric IOL appears more likely to be misoriented in a counterclockwise direction; no such bias was observed with the AcrySof Toric, the Trulign® Toric, or the Staar Toric IOLs. Keywords: rotation, AcrySof, Tecnis, toric back-calculator, cylinder

  8. Astigmatism treatment during phacoemulsification: a review of current surgical strategies and their rationale

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    Giuliano de Oliveira Freitas

    2013-12-01

    Full Text Available Preexisting corneal astigmatism, present at the time of cataract surgery, is reviewed in detail throughout this article on its most important aspects such as occurrence rates, clinical relevance and current treatment options. Special emphasis is given to the latter aspect. Each method's rationale, advantage and limitation ishigh lightened. Comparisons between treatment options, whenever possible, are also provided.

  9. [Visual acuity and astigmatism after keratoplasty. Differences between the guided trephine system and motor trephine].

    Science.gov (United States)

    Fejza, A; Schafia, A; Löw, U; Hille, K; Seitz, B

    2013-05-01

    The purpose of this study was to assess the differences in postoperative visual acuity, astigmatism, and selected postoperative complications between a guided trephine system (GTS) and motor trephine after penetrating keratoplasty. In this retrospective analysis 74 patients who had undergone penetrating keratoplasty either by GTS (n = 53) or by motor trephine (Motortrepan) (n = 21) were included. Both patient groups included in this analysis were selected to ensure a homogeneous distribution of preoperative parameters to the greatest possible extent. However, some significant differences in patient selection between the two groups could not be avoided. Patients in the motor trephine group were older (mean age 68.4 years vs 56.4 years; p astigmatism (1.36 vs. 2.0 dpt., p = 0.39). However, at the time of final corneal suture removal (2.23 vs. 3.5 dpt., p = 0.03) and at a postoperative control 1 year after final suture removal (2.29 vs. 3.85 dpt., p = 0.005) the amount of astigmatism in the motor trephine group was found to be significantly higher. In summary penetrating kerastoplasty using the motor trephine was found to result in significantly higher postoperative astigmatism than those performed with the GTS.

  10. Astigmatism outcomes of scleral tunnel and clear corneal incisions for congenital cataract surgery.

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    Bar-Sela, S M; Spierer, A

    2006-09-01

    To evaluate astigmatism outcomes after congenital cataract surgery with intraocular lens implantation using clear corneal or scleral tunnel incisions. We retrospectively reviewed the medical records of 46 children (67 eyes), aged 2 months to 12 years, who had undergone nontraumatic cataract extraction and intraocular lens implantation between 1996 and 2001, using a scleral tunnel incision (group 1), or a clear corneal incision (group 2). Refractive astigmatism was measured at 1 week, 3 months, and 5 months after surgery. Paired t-test was used to compare those variables, and Spearman's correlation was used to determine their relation to patient's age. Mean+/-SD astigmatism at 1 week postoperatively was 3.1+/-2.8 Diopter (D) and 2.1+/-1.7 D in groups 1 and 2, respectively. It significantly reduced to 1.1+/-1.2 D and 0.9+/-1.0 D, respectively, in the two groups at 5 months postoperatively (Pastigmatism (group 1: r=0.64; P=0.001; group 2: r=-0.58; P=0.003), and with the change in cylinder magnitude between 1 week and 3 months postoperatively (group 1: r=-0.67; P=0.001; group 2: r=0.50; P=0.013). Children who underwent congenital cataract surgery using clear corneal or scleral tunnel incisions showed high postoperative astigmatism at 1 week postoperatively, which spontaneously reduced during 5 months follow-up. Therefore, suture removal is not necessary in those cases.

  11. Precise and unbiased estimation of astigmatism and defocus in transmission electron microscopy

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    Vulovic, M.; Franken, E.; Ravelli, R.B.G.; Van Vliet, L.J.; Rieger, B.

    2012-01-01

    Defocus and twofold astigmatism are the key parameters governing the contrast transfer function (CTF) in transmission electron microscopy (TEM) of weak phase objects. We present a new algorithm to estimate these aberrations and the associated uncertainties. Tests show very good agreement between

  12. Meridional lenticular astigmatism associated with bilateral concurrent uveal metastases in renal cell carcinoma

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    Priluck JC

    2012-11-01

    Full Text Available Joshua C Priluck, Sandeep Grover, KV ChalamDepartment of Ophthalmology, University of Florida College of Medicine, Jacksonville, FL, USAPurpose: To demonstrate a case illustrating meridional lenticular astigmatism as a result of renal cell carcinoma uveal metastases.Methods: Case report with images.Results: Clinical findings and diagnostic testing of a patient with acquired meridional lenticular astigmatism are described. The refraction revealed best-corrected visual acuity of 20/20–1 OD (−2.50 + 0.25 × 090 and 20/50 OS (−8.25 + 3.25 × 075. Bilateral concurrent renal cell carcinoma metastases to the choroid and ciliary body are demonstrated by utilizing ultrasonography, ultrawidefield fluorescein angiography, and unique spectral-domain optical coherence tomography.Conclusions: Metastatic disease should be included in the differential of acquired astigmatism. Spectral-domain optical coherence tomography, ultrawidefield fluorescein angiography, and ultrasonography have roles in delineating choroidal metastases.Keywords: astigmatism, metastasis, optical coherence tomography, renal cell carcinoma

  13. Results of toric intraocular lenses for post-penetrating keratoplasty astigmatism.

    Science.gov (United States)

    Wade, Matthew; Steinert, Roger F; Garg, Sumit; Farid, Marjan; Gaster, Ronald

    2014-03-01

    Evaluate the usefulness of toric intraocular lens (IOL) implantation during cataract surgery in patients after penetrating keratoplasty (PKP). Retrospective case review. A total of 21 eyes of 16 patients with prior PKP and moderate to high regular astigmatism after full suture removal underwent phacoemulsification and implantation of a single-piece acrylic toric IOL (SN6AT series; Alcon, Fort Worth, TX). Patients underwent comprehensive examinations at standard intervals, including visual acuity, manifest refraction, and corneal topography. Uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) expressed as the logarithm of the minimum angle of resolution (logMAR) and manifest refraction astigmatism. From preoperatively to the last visit (mean, 14.7 ± standard deviation 12.8 months), the 21 eyes had significant improvement in UDVA (logMAR, 0.90 ± 0.48 to 0.23 ± 0.25; P = 0.0001) and CDVA (logMAR, 0.31 ± 0.14 to 0.08 ± 0.13; P = 0.0001). A total of 14 of 21 eyes (67%) and 17 of 21 eyes (81%) had UDVA and CDVA of ≥ 20/30, respectively. Preoperative topographic astigmatism was 4.57 ± 2.05 diopters (D). Postoperative manifest refraction astigmatism was 1.58 ± 1.25 D overall, but lower (0.75 ± 0.54 D) in the T7-T9 subgroup (excluding 1 outlier whose corneal astigmatism doubled after surgery) than in the T4-T6 subgroup (1.88 ± 1.28 D; P = 0.013). A total of 16 of all 21 eyes (76.2%) and 8 of 9 eyes (89%) in the T7-T9 subgroup were within 1 D of postoperative manifest astigmatism as predicted or better. Toric IOLs placed during cataract surgery after PKP and full suture removal can reduce manifest refraction cylinder to predictably low levels with corresponding improvement in UDVA and CDVA in patients with moderate to high regular preoperative topographic astigmatism. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  14. Pseudophakic astigmatism reduction with femtosecond laser-assisted corneal arcuate incisions: a pilot study

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    Blehm C

    2017-01-01

    Full Text Available Clayton Blehm,1 Richard Potvin2 1Gainesville Eye Associates, Gainesville, GA, 2Science in Vision, Akron, NY, USA Purpose: The aim of this study was to assess the effectiveness of the Verion-LenSx guided arcuate incision technique to reduce refractive astigmatism in a pseudophakic population. Patients and methods: A prospective single-arm study was conducted in which one or both eyes of subjects required reduction of 1.0–2.0 D of refractive astigmatism after previous cataract surgery or refractive lens exchange. The surgeon used the refractive cylinder in the eye and the Woodcock astigmatism nomogram for preoperative planning, while the LenSx femtosecond laser with the Verion Image Guided System was used to create all arcuate incisions. The primary outcome measure was the uncorrected monocular distance visual acuity (UCVA. Secondary outcome measures included the change in corneal astigmatism, the change in refractive astigmatism, the best-corrected visual acuity and spectacle independence at distance from preoperative stage to 1 month and 2 months postoperatively. Results: Twenty-eight eyes of 18 subjects were treated. The best-corrected visual acuity at the 2-month postoperative (PO stage was not statistically significantly different from the preoperative visual acuity (0.02 logarithm of the minimum angle of resolution [logMAR] in both cases, P>0.05. Uncorrected visual acuity was statistically significantly better at the 2-month PO stage relative to the preoperative value (0.14 versus 0.34 logMAR, P<0.01. The mean change in refractive cylinder from the preoperative stage to the 2-month PO stage was 1.0 D. At the 2-month PO stage, two-thirds of the subjects (12/18 reported that they did not use glasses for distance vision and that their spectacle use for distance vision at 2 months was “lower” or “much lower” than the preoperative stage; in 71% of eyes (20/28, the residual refractive cylinder was ≤0.50 D. Vector changes in

  15. Effects of corneal irregular astigmatism on visual acuity after conventional and femtosecond laser-assisted Descemet's stripping automated endothelial keratoplasty.

    Science.gov (United States)

    Tomida, Daisuke; Yamaguchi, Takefumi; Ogawa, Akiko; Hirayama, Yumiko; Shimazaki-Den, Seika; Satake, Yoshiyuki; Shimazaki, Jun

    2015-07-01

    To compare short-term outcomes of Descemet's stripping automated endothelial keratoplasty (DSAEK) using a graft prepared with either a femtosecond laser or a microkeratome. Thirty-eight patients underwent DSAEK with grafts prepared with either a femtosecond laser (f-DSAEK; 21 eyes) or a microkeratome (m-DSAEK; 17 eyes). Visual acuity, endothelial cell density, regular astigmatism and irregular astigmatism were compared between the two groups preoperatively and at 1, 3, and 6 months post-operatively. Fourier analysis was conducted to calculate astigmatism of the anterior and posterior surfaces, and total cornea, using anterior segment optical coherence tomography (AS-OCT). Visual acuity (logMAR) improved from 1.20 ± 0.60 to 0.43 ± 0.25 after m-DSAEK (P astigmatism of the total cornea and the posterior surface was significantly larger after f-DSAEK than after m-DSAEK, although there was no significant difference in irregular astigmatism of the anterior surface at 6 months. Postoperative visual acuity was significantly correlated with the postoperative irregular astigmatism of the total cornea (r = 0.6657 and P astigmatism caused by posterior surface irregularities.

  16. Toric soft contact lens fit in a postoperative LASIK keratoectasia patient with high and irregular astigmatism.

    Science.gov (United States)

    Roncone, David P

    2011-12-01

    Keratoectasia is a rare but well-known complication after laser-assisted in situ keratomileusis (LASIK). Patients with this condition can have high and irregular astigmatism. When the treatment of the high astigmatic correction cannot be accomplished surgically or when the keratoectasia patient rejects surgical enhancement, optical correction with devices such as soft or rigid gas-permeable contact lenses may be pursued. In fact, toric soft contact lenses are a good first option for fitting postoperative keratoectasia patients. A 58-year-old white male presented for an examination with a complaint of decreased distance vision in the right eye (OD) after having traditional LASIK for myopia with astigmatism in both eyes (OU) in 1999 and limbal relaxing incision enhancement OD in 2003. Refraction showed high mixed astigmatism OD (+1.75 -5.75×075). Slit lamp examination found irregularity of the cornea, evidenced by an inferior cone with pigmented Fleischer ring OD. Video keratometry had keratometry readings of 43.50 at 160, 39.87 at 070, elevated shape measure (0.40), elevated corneal irregularity measure (3.96), an inferior cone on the elevation map, and asymmetric bowtie with elongation inferonasally on the axial map, which confirmed the diagnosis of postoperative keratoectasia. Because new surgical treatments at that time for corneal ectasia were in their infancy and not approved by the U.S. Food and Drug Administration, the patient opted for a trial toric soft contact lens fitting, which improved his corrected distance visual acuity to 20/25. This case report confirms that toric soft contact lenses are a good first choice in fitting patients with high and irregular astigmatism from postoperative LASIK corneal ectasia. It also confirms that excellent vision and comfort with toric soft contact lenses is possible in these patients. Published by Elsevier Inc.

  17. Office-based Relaxing Incision Procedure for Correction of Astigmatism after Deep Anterior Lamellar Keratoplasty

    Science.gov (United States)

    Javadi, Mohammad Ali; Feizi, Sepehr; Mirbabaee, Firooz; Fekri, Yousef

    2017-01-01

    Purpose: To report the outcomes of a simple and effective office-based procedure for the correction of astigmatism after deep anterior lamellar keratoplasty (DALK). Methods: This study enrolled 24 consecutive keratoconic eyes that developed an intolerable amount of graft astigmatism after DALK. The location and extension of steep semi-meridians were determined using corneal topography. Office-based relaxing incision procedures were performed at the slit-lamp biomicroscope using a 27-gauge needle. Relaxing incisions were made at the donor-recipient interface on one side of the steepest meridian with an arc length of 45° to 60° and an initial depth of approximately 70–80% of the corneal thickness. Topography was performed after 30–40 minutes and the initial incision was enhanced in depth and length. If an acceptable amount of astigmatism was not achieved, another incision was created at the opposite semi-meridian during the same session. Results: Mean follow-up period was 13.1 ± 7.4 months. Mean preoperative best spectacle corrected visual acuity was 0.26 ± 0.14 logMAR, increasing to 0.22 ± 0.09 logMAR after the procedure (P = 0.20). Mean spherical equivalent refractive error increased from − 4.64 ± 3.06 diopters (D) preoperatively to −6.06 ± 3.15 D postoperatively (P = 0.01). Mean keratometric astigmatism was reduced by 2.95 ± 3.43 D and 5.16 ± 2.97 D measured using subtraction and vector analysis methods, respectively (P astigmatism after DALK. This approach effectively decreases the need for the more costly alternative in the operating room. PMID:28540006

  18. Relaxing incisions combined with adjustment sutures for post-deep anterior lamellar keratoplasty astigmatism in keratoconus.

    Science.gov (United States)

    Javadi, Mohammad Ali; Feizi, Sepehr; Mirbabaee, Firooz; Rastegarpour, Ali

    2009-12-01

    To find an effective and reliable method to correct astigmatism after deep anterior lamellar keratoplasty (DALK) in patients with keratoconus. This interventional case series included 14 eyes of 14 patients with keratoconus (12 males) undergoing graft refractive surgery (GRS) for intolerable post-DALK astigmatism. The technique of GRS for the 5 initial cases consisted of only relaxing incisions at the steep meridian in the graft-host interface down to Descemet membrane. For the rest, the relaxing incisions at the steep meridian were accompanied by simultaneous suturing and the effect of the relaxing incisions was controlled through selective suture removal starting a few days after the operation. The main outcomes were uncorrected and corrected visual acuity and change in refractive and keratometric astigmatism using subtraction and vector analysis methods. Mean patient age was 29.36 +/- 6.2 years. Mean time interval from complete suture removal to GRS and follow-up period were 4.5 +/- 2.0 months and 12.0 +/- 7.4 months, respectively. Mean preoperative best-corrected visual acuity was 0.29 +/- 0.1, increasing to 0.22 +/- 0.1 logarithm of minimum angle of resolution after the operation (P = 0.007). Average keratometric astigmatism was reduced by 3.8 and 5.5 diopters measured with subtraction and vector analysis methods, respectively. Four of 5 eyes that had only relaxing incisions initially required suturing of the incisions because of overcorrection, whereas preliminary results showed none of the 9 patients undergoing simultaneous relaxing incisions and suturing required further intervention. Relaxing incisions and suturing at the steep meridian followed by selective suture removal can effectively and predictably reduce post-DALK astigmatism in patients with keratoconus.

  19. Comparison of the induced astigmatism after temporal clear corneal tunnel incisions of different sizes.

    Science.gov (United States)

    Kohnen, T; Dick, B; Jacobi, K W

    1995-07-01

    A prospective, randomized study compared the surgically induced astigmatism after 3.5 mm, 4.0 mm, and 5.0 mm temporal corneal tunnel incisions over six months. We studied 60 eyes of 60 patients who had phacoemulsification through a two-step clear corneal tunnel incision and implantation of one of three posterior chamber intraocular lenses (IOLs). Patients were divided into three groups of 20 each: Group A, cartridge injection of a foldable plate-haptic silicone IOL through a 3.5 mm self-sealing incision; Group B, cartridge injection of a disc silicone IOL through a 4.0 mm self-sealing incision; Group C, 5.0 mm optic poly(methyl methacrylate) IOL through a 5.0 mm incision with one radial suture. Corneal topography data were obtained using a computerized videokeratographic analysis system preoperatively and one week and six months postoperatively. Vector analysis was performed to calculate the surgically induced astigmatism. After the first postoperative week, mean induced astigmatism was 0.63 diopters (D) (+/- 0.41) in Group A, 0.64 D (+/- 0.35) in Group B, and 0.91 D (+/- 0.77) in Group C. After six months, it was 0.37 D (+/- 0.14) in Group A, 0.56 D (+/- 0.34) in Group B, and 0.70 D (+/- 0.50) in Group C. Surgically induced astigmatism was significantly lower in Group A than in Group B (P incisions induced clinically minimal astigmatism over six months postoperatively depending on incision size.

  20. Effect of a standard paired arcuate incision and augmentation sutures on postkeratoplasty astigmatism.

    Science.gov (United States)

    Koay, P Y; McGhee, C N; Crawford, G J

    2000-04-01

    To analyze the efficacy of a standardized paired arcuate incision and augmentation suture technique in the treatment of various levels of post-penetrating keratoplasty (PKP) astigmatism. Lions Eye Institute, Royal Perth Hospital, Perth, Australia, and University of Dundee Department of Ophthalmology, Dundee, United Kingdom.A standardized paired arcuate incision and paired augmentation suture technique was used to treat 34 eyes with post-PKP astigmatism ranging from -3.50 to -20.00 diopters (D) at the spectacle plane. The technique consisted of paired arcuate incisions of 3 clock hours, 480 microm deep in the graft-host junction, and 2 pairs of augmentation 10-0 nylon sutures. The mean preoperative cylinder was -9.14 D +/- 4.38 (SD) and the mean postoperative cylinder, -3.59 +/- 1.92 D at the corneal plane after a mean follow-up of 50 +/- 43 weeks. This represents an empirical reduction in mean cylinder of 5. 55 D (60.7%). The Alpins correction index (surgically induced astigmatism [SIA] divided by target induced astigmatism) was calculated for each case, and the mean was 1.01 +/- 0.34, with a median of 0.91. Approximately 53.1% of cases achieved a correction index between 0.80 and 1.20, and the correction index correlated poorly with the initial magnitude of cylinder. A direct numerical relationship between SIA and the initial magnitude of cylinder was observed, although a standard surgical procedure was used in all cases.A simple standardized technique using paired arcuate incisions in the graft-host junction with paired augmentation sutures reduces the amount of cylinder in proportion to the magnitude of the preoperative cylinder and effectively reduces post-PKP astigmatism.

  1. Intrastromal Corneal Ring Segments for Astigmatism Correction after Deep Anterior Lamellar Keratoplasty

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    Júlio C. D. Arantes

    2017-01-01

    Full Text Available Background. To evaluate the change in corneal astigmatism after intrastromal corneal ring segment (ICRS implantation in keratoconus patients with previous deep anterior lamellar keratoplasty (DALK. Design was a longitudinal, retrospective, interventional study. The study included 25 eyes of 24 patients with keratoconus who had DALK performed at least two years prior to ICRS implantation. All patients had a clear corneal graft with up to 8.00 D of corneal astigmatism and intolerance to contact lenses. The studied parameters were age, sex, corrected distance visual acuity (CDVA, maximum keratometry (K1, minimum keratometry (K2, spherical equivalent, and astigmatism. There was a statistically significant decrease in the postintervention analysis as follows: 3.5 D reduction in K1 (p<0.001; 1.53 D in K2 (p=0.005; and 2.52 D (p<0.001 in the average K. The spherical equivalent reduced from −3.67 D (±2.74 to −0.71 D (±2.35 (p<0.001. The topographic astigmatism reduced from 3.87 D preoperatively to 1.90 D postoperatively (p<0.001. The CDVA improved from 0.33 (±0.10 to 0.20 (±0.09, p<0.001. ICRS implantation is a useful option for the correction of astigmatism after DALK as it yields significant visual, topographic, and refractive results.

  2. Development of astigmatism and anisometropia in preterm children during the first 10 years of life: a population-based study.

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    Larsson, Eva K; Holmström, Gerd E

    2006-11-01

    To assess the development of astigmatism and anisometropia to 10 years of age in preterm children, previously included in a population-based study on the incidence of retinopathy of prematurity. Cycloplegic retinoscopies were performed in 198 preterm children at 6 months, 2(1/2) years, and 10 years of age. We analyzed the development of astigmatism of 1 diopter (D) or more and anisometropia of 1 D or more. The amount and prevalence of astigmatism declined between 6 months and 2(1/2) years of age and then remained stable. We found no difference in the course of astigmatism at different ages with regard to stage of retinopathy of prematurity. The amount of anisometropia increased, but its prevalence remained unchanged. Multiple regression analyses showed that astigmatism of 1 D or more at 2(1/2) years of age and cryotreated severe retinopathy of prematurity were risk factors for astigmatism at 10 years of age, and that anisometropia of 2 D or more at 2(1/2) years of age was a risk factor for anisometropia at 10 years of age. The development of astigmatism and anisometropia showed a similar course, regardless of stage of retinopathy of prematurity. The retinoscopy findings at 6 months of age were of no value in predicting astigmatism and anisometropia at 10 years of age, but the refraction at 2(1/2) years of age was. Retinoscopy at about 2(1/2) years of age in all preterm children may be useful for detecting astigmatism and anisometropia that will persist in children of school age.

  3. Safety and efficacy of femtosecond laser-assisted arcuate keratotomy to treat irregular astigmatism after penetrating keratoplasty.

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    Fadlallah, Ali; Mehanna, Chadi; Saragoussi, Jean-Jacques; Chelala, Elias; Amari, Belkacem; Legeais, Jean-Marc

    2015-06-01

    To determine the refractive efficacy, predictability, stability, and complication rate of Intralase femtosecond laser-assisted astigmatic keratotomy (AK) for irregular astigmatism after penetrating keratoplasty (PKP). Ophthalmology Department, Hôtel-Dieu, Paris, France. Retrospective case series. Femtosecond laser-assisted AK was performed to treat high irregular astigmatism (>5.0 diopters [D]) after PKP. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, manifest refraction, vector analysis, and complications were evaluated. The study evaluated 62 eyes of 57 patients over a mean follow-up of 28 months ± 3.5 (SD). Preoperatively, the mean CDVA was 0.51 ± 0.26 logMAR and the mean UDVA was 0.98 ± 0.24 logMAR; 6 months postoperatively, the mean CDVA and UDVA improved to 0.40 ± 0.22 logMAR and 0.60 ± 0.2 logMAR, respectively (both P astigmatism was 7.1 ± 1.72 D; 6 months postoperatively, the mean refractive astigmatism was 2.6 ± 2.4 D (P astigmatism remained stable up to the end of follow-up. The efficacy index was 0.81 at 6 months and 0.67 at 2 years. There were 2 cases of microperforation, 3 cases of infectious keratitis, 3 graft rejection episodes, and 1 case of endophthalmitis. Overcorrection occurred in 12 eyes. Femtosecond laser-assisted AK was effective in reducing irregular astigmatism after PKP. Predictability of astigmatism correction is variable over time with a decrease in the efficacy index 2 years postoperatively. Refinement of the treatment nomogram for femtosecond laser-assisted AK for high astigmatism after PKP remains a major issue. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  4. ANALYSIS OF CORNEAL ASTIGMATISM BEFORE AND AFTER PTERYGIUM SURGERY- A PROSPECTIVE STUDY IN PATIENTS ATTENDING KIMS, HUBLI

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    Y. B. Bajantri

    2017-10-01

    Full Text Available BACKGROUND Pterygium is a very common degenerative condition seen in Indian subcontinent. It is a wing-shaped fibrovascular encroaching up on the cornea from either sides. The prevalence rate is 5.2%. Pterygium is known to affect refractive astigmatism. The induced astigmatism may become significant to cause visual distortion, even though the pterygium remains distant from visual axis induced astigmatism maybe either “with-the-rule” or “against-the-rule.” The aim of the study is to- 1. Compare preoperative with postoperative astigmatism in case of pterygium. 2. Assess the amount of astigmatism in case of pterygia of different lengths measured from the limbus over the cornea. MATERIALS AND METHODS The study included 70 eyes of 70 patients with primary pterygium. Preoperative evaluation included pterygium size, visual acuity, keratometry and refraction with subjective correction. Patients included in the study were divided into three groups based on length of pterygium encroaching on cornea (1 to 2 mm, 2 to 3 mm, >3 mm. Each eye underwent bare sclera pterygium excision. Postoperative visual acuity, keratometry and refraction were evaluated on 1st day, at the end of 1st week, 4 th week and 9th week. The pre and postoperative results were compared and analysed. RESULTS An average of all 70 cases with mean pterygium length 3.2 mm had a mean keratometry astigmatism of 1.84 ± 0.89D preoperatively and 0.514 ± 0.52D postoperatively indicating a reduction of pterygium-induced corneal astigmatism by 1.45 ± 0.77D (p value <0.0001, which was statistically significant. CONCLUSION Pterygium-induced corneal astigmatism is directly proportional to the size of the pterygium. Thus, early surgical excision reduces the corneal astigmatism, and hence, improves the visual acuity.

  5. Optimal incision sites to obtain an astigmatism-free cornea after cataract surgery with a 3.2 mm sutureless incision.

    Science.gov (United States)

    Matsumoto, Y; Hara, T; Chiba, K; Chikuda, M

    2001-10-01

    To determine the optimal incision to eliminate astigmatism after cataract extraction. Hara Eye Hospital, Utsunomiya, Japan. Patients having cataract extraction through a 3.2 mm corneal limbal incision without limbal sutures were divided into 2 groups. Group 1 comprised 98 eyes of 80 patients without preoperative astigmatism and Group 2, 72 eyes of 62 patients with no astigmatism postoperatively. In Group 1, the incisions that caused postoperative corneal changes were retrospectively evaluated. In Group 2, the types of incisions that induced an astigmatism-free cornea postoperatively were retrospectively studied. Patients were examined preoperatively and 6 months postoperatively. In Group 1, 23 of 40 eyes (57.5%) with an incision between 9 and 12 o'clock (BENT incision) and 10 of 58 eyes (17.2%) with an incision at 12 o'clock remained astigmatism free postoperatively (P incision and 17 (29.3%) with a 12 o'clock incision had astigmatism greater than 1.0 diopter (D) postoperatively (P astigmatism. No eye with more than 1.2 D of astigmatism was astigmatism free postoperatively, even when the incision was made at the steepest meridian. The results indicate that to reduce astigmatism in eyes with preoperative astigmatism of 0.5 D or more, a limbal 3.2 mm BENT incision should be placed at 10:30 o'clock. To prevent astigmatism postoperatively, the incision should be placed at the steepest meridian in eyes with preoperative astigmatism greater than 0.5 D; for preoperative astigmatism greater than 1.2 D, a 3.2 mm incision at the corneal limbus is insufficient and a wider incision or an additional incision is required.

  6. Refractive astigmatism and the toricity of ocular components in human infants.

    Science.gov (United States)

    Mutti, Donald O; Mitchell, G Lynn; Jones, Lisa A; Friedman, Nina E; Frane, Sara L; Lin, Wendy K; Moeschberger, Melvin L; Zadnik, Karla

    2004-10-01

    Many studies have characterized astigmatism in infancy, but few have been longitudinal or contained ocular component data. This study characterized the frequency, orientation, and longitudinal change with age of infant astigmatism. Additional factors investigated were the influence of early astigmatism on emmetropization and its relation to corneal and lenticular toricity. Three hundred two infants were enrolled in the study. Of these, 298 provided data for at least one visit at 3 +/- 1 months, 9 +/- 1 months, 18 +/- 2 months, and 36 +/- 3 months. Testing included cycloplegic retinoscopy (cyclopentolate 1%), video-based keratophakometry, and ultrasonography over the closed eyelid. Astigmatism > or =1.00 DC was common at 3 months of age (41.6%) but decreased in prevalence to 4.1% by 36 months (p < 0.0001). The most common orientation was with-the-rule at 3 months (37.0% compared with 2.7% for against-the-rule) but against-the-rule at 36 months (3.2% compared with 0.9% for with-the-rule). Most of the change in the average value of the horizontal/vertical component of astigmatism (J0) occurred between 3 and 9 months (-0.26 +/- 0.36 D; p < 0.0001) with no significant change between 9 and 36 months (-0.05 +/- 0.36 D; p=0.09). Spherical equivalent refractive error was not correlated with J0 at 3 and 9 months (R=0.002, p=0.48 and R=0.001, p=0.56, respectively). The two were only weakly correlated at 18 and 36 months (R=0.06 for each age, p <0.0001, p=0.0002, respectively). Changes in spherical equivalent between 3 and 9 months were unrelated to either the initial value of J0 (partial R for J0=0.0001; p=0.85) or the change in J0 (partial R for change in J0=0.0031; p=0.31). Across all the ages, corneal toricity was with-the-rule, and lenticular toricity was against-the-rule (produced by the toricity of the posterior lens surface). The cornea and anterior lens surface became more spherical with age, contributing to the shift away from with-the-rule refractive astigmatism

  7. Extended depth of focus intra-ocular lens: a solution for presbyopia and astigmatism

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    Zlotnik, Alex; Raveh, Ido; Ben Yaish, Shai; Yehezkel, Oren; Belkin, Michael; Zalevsky, Zeev

    2010-02-01

    Purpose: Subjects after cataract removal and intra-ocular lens (IOL) implantation lose their accommodation capability and are left with a monofocal visual system. The IOL refraction and the precision of the surgery determine the focal distance and amount of astigmatic aberrations. We present a design, simulations and experimental bench testing of a novel, non-diffractive, non-multifocal, extended depth of focus (EDOF) technology incorporated into an IOL that allows the subject to have astigmatic and chromatic aberrations-free continuous focusing ability from 35cm to infinity as well as increased tolerance to IOL decentration. Methods: The EDOF element was engraved on a surface of a monofocal rigid IOL as a series of shallow (less than one micron deep) concentric grooves around the optical axis. These grooves create an interference pattern extending the focus from a point to a length of about one mm providing a depth of focus of 3.00D (D stands for Diopters) with negligible loss of energy at any point of the focus while significantly reducing the astigmatic aberration of the eye and that generated during the IOL implantation. The EDOF IOL was tested on an optical bench simulating the eye model. In the experimental testing we have explored the characteristics of the obtained EDOF capability, the tolerance to astigmatic aberrations and decentration. Results: The performance of the proposed IOL was tested for pupil diameters of 2 to 5mm and for various spectral illuminations. The MTF charts demonstrate uniform performance of the lens for up to 3.00D at various illumination wavelengths and pupil diameters while preserving a continuous contrast of above 25% for spatial frequencies of up to 25 cycles/mm. Capability of correcting astigmatism of up to 1.00D was measured. Conclusions: The proposed EDOF IOL technology was tested by numerical simulations as well as experimentally characterized on an optical bench. The new lens is capable of solving presbyopia and astigmatism

  8. Induced astigmatism after cataract surgery - a retrospective analysis of cases from the University of Port Harcourt Teaching Hospital, Nigeria

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    A. O. Adio

    2011-12-01

    Full Text Available Visual rehabilitation after cataract surgery may often be disappointing due to induction of corneal astigmatism following issues in realigning, point to point, the corneal wound margin in the process of surgery despite biometry and use of the appropriateintraocular lens. The purpose of this study is to determine the amount of surgically induced astigmatism after sutured cataract extraction-extracapsular cataract extraction (ECCE and intracapsular cataract extraction (ICCE and intraocular lens (IOLimplantation in the University of Port Harcourt Teaching Hospital, Port Harcourt, Nigeria. Folders of all cataract patients operated on in the eye theatre of the aforenamed tertiary facility between2002 and 2006 were considered.  Relevant patient details and intraoperative and postoperative management were examined and reported upon. One hundred and fourteen eyes (114 of one hundred patients who had cataract surgeries done within the five-year period of this study were examined. ECCE + IOL implantation were examined in the period under review. The post-operative refraction objectively and subjectively was retrieved from the records of each patient. The post-operative cylinderpower (total astigmatism was recorded.Of 114 eyes, only 83 eyes (72.8% had refraction results postoperatively due to loss of fol-low-up. The total number with astigmatism was 57(68.7%. Forty-two had against-the-rule (73.7%, twelve (21.1% with-the-rule, while five (0.09% were oblique. The mean post-operative astigmatism was 1.85 D. The surgically induced corneal astigmatism was highest with ECCE with PCIOL. Astigmatism less than 2 D was highest in this group (ECCE with IOL while ICCE with ACIOL had the highest number with astigmatism in the range between 2 D and 4 D. The total astigmatism which was mainly with-the-rule (vertical plus cylinder did not seem to impair severely the post-operative visual acuity of the patients.In conclusion, surgically induced astigmatism affected almost

  9. The effects of surgical factors on postoperative astigmatism in patients enrolled in the Infant Aphakia Treatment Study (IATS).

    Science.gov (United States)

    Wall, Palak B; Lee, Jason A; Lynn, Michael J; Lambert, Scott R; Traboulsi, Elias I

    2014-10-01

    To evaluate the effect of surgical factors on postoperative astigmatism in infants undergoing cataract extraction with or without intraocular lens (IOL) implantation. The Infant Aphakia Treatment Study is a multicenter clinical trial in which 114 infants with unilateral congenital cataracts were randomized to undergo cataract extraction with IOL placement or contact lens aphakic correction. Surgical videos were reviewed with regard to incision type and location, whether the incision was extended, the number of sutures placed, and technique of closure. Corneal astigmatism was measured using a handheld keratometer prior to surgery and at 1 year of age. Corneal astigmatism decreased from a mean of 1.92 D at baseline to 1.62 D at age 1 year in the contact lens group but remained almost unchanged from 2.00 D to 2.09 D in the IOL group (P = 0.023). There was no statistical difference between the amount of corneal astigmatism with regard to incision type (P = 0.214) and no increase in astigmatism with extension of the incision to facilitate IOL placement (P = 0.849) at 1 year. The number of sutures and technique of closure did not influence the amount of astigmatism at 1 year. At the age of 1 year following cataract extraction in infants, contact lens correction and the lack of IOL placement are associated with a significant decrease in postoperative corneal astigmatism compared to IOL placement. No other surgical factors considered in this study had a statistically significant effect on corneal astigmatism. Copyright © 2014 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

  10. Comparison of the Keratometric Corneal Astigmatic Power after Phacoemulsification: Clear Temporal Corneal Incision versus Superior Scleral Tunnel Incision

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    Yongqi He

    2009-01-01

    Full Text Available Objective. This is prospective randomized control trial to compare the mean keratometric corneal astigmatism diopter power (not surgical induced astigmatism among preop and one-month and three-month postop phacoemulcification of either a clear temporal corneal incision or a superior scleral tunnel Incision, using only keratometric astigmatic power reading to evaluate the difference between the two cataract surgery incisions. Methods. 120 patients (134 eyes underwent phacoemulcification were randomly assigned to two groups: Group A, the clear temporal corneal incision group, and Group B, the superior scleral tunnel incision group. SPSS11.5 Software was used for statistical analysis to compare the postsurgical changes of cornea astigmatism on keratometry. Results. The changes of corneal astigmatic diopter in Groups A and B after 3 month postop from keratometric reading were 1.04 + 0.76 and 0.94 + 0.27, respectively (=.84>.05, which showed no statistic significance difference. Conclusion. The incision through either temporal clear cornea or superior scleral tunnel in phacoemulcification shows no statistic difference in astigmatism change on keratometry 3-month postop.

  11. Characteristics of Corneal Astigmatism of Anterior and Posterior Surface in a Normal Control Group and Patients With Keratoconus.

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    Shajari, Mehdi; Friderich, Stefan; Pour Sadeghian, Miad; Schmack, Ingo; Kohnen, Thomas

    2017-04-01

    To evaluate and compare power and axis orientation of anterior and posterior astigmatism in eyes with keratoconus with healthy eyes. In this retrospective cohort study, we examined 861 eyes of 494 patients diagnosed with keratoconus at the Department of Ophthalmology, University Hospital Frankfurt, and 256 eyes of 256 healthy individuals. Using a Scheimpflug device (Pentacam HR), we measured the magnitude and axis orientation of anterior and posterior corneal astigmatism, corneal thickness, and conus location. The results were compared between different stages of the disease according to the Amsler-Krumeich classification and the control group. Magnitude of corneal astigmatism was 3.47 ± 2.10 diopters (D) on the anterior surface and 0.69  ± 0.40 D on the posterior surface in eyes across all keratoconus stages. We found a significant increase of anterior and posterior corneal astigmatism with progression of disease (P keratoconus a match between anterior and posterior alignment when alignment was vertical in 97% of eyes, 46% when oblique and 61% when horizontal (Cohen kappa coefficient κ = 0.55, P keratoconus, posterior axis alignment of corneal astigmatism is in line with alignment of the anterior surface in the majority of cases. Posterior astigmatism axis alignment could potentially be used in algorithms to support diagnosis and staging of keratoconus.

  12. AcrySof toric intraocular lens for post-keratoplasty astigmatism

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    Nishant Gupta

    2012-01-01

    Full Text Available We report a 63-year-old male who had undergone left eye optical penetrating keratoplasty for central leucomatous corneal opacity 10 years earlier. The eye had clear donor graft with residual astigmatism of −6.50 diopter cylinder (DC at 30°. The patient underwent clear corneal phacoemulsification with implantation of +6.0 D spherical equivalent AcrySof SN60T9 intraocular lens (IOL. Postoperatively, at 10 months, the patient had distance corrected visual acuity of 20/30 with −2.00 DC at 20°. AcrySof toric IOL offers an effective treatment option for post-keratoplasty high corneal astigmatism in patients with cataract.

  13. Customized photorefractive keratectomy for the correction of regular and irregular astigmatism after penetrating keratoplasty.

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    Ohno, Kenji

    2011-10-01

    To report visual, wavefront, and topographic outcomes in 5 post-penetrating keratoplasty patients who underwent customized aspheric topography-guided photorefractive keratectomy for high astigmatism or severe higher-order aberrations. A chart review was performed for data collection. The custom aspheric transition zone ablation algorithm (CATz) with the CX III excimer was used for all treatments. Ablations were calculated based on corneal elevation data. Phototherapeutic keratectomy was the first step of the procedure. Visual acuity, corneal higher-order wavefront aberrations (Zernike sixth order and 4-mm diameter), corneal topography, and patient satisfaction were evaluated preoperatively and at the last visit postoperatively (range, 3 months to 4.5 years). The paired t test was used for statistical comparison of higher-order aberrations, with P astigmatism after penetrating keratoplasty.

  14. The effect of relaxing incisions with multiple compression sutures on post-keratoplasty astigmatism.

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    Lustbader, J M; Lemp, M A

    1990-06-01

    We describe a surgical technique for correction of astigmatism following penetrating keratoplasty performed after all keratoplasty sutures have been removed. Two relaxing incisions of 3 clock hours, at 3/4 depth, 0.5 mm inside the keratoplasty wound are used in combination with two sets of three compression sutures placed 90 degrees from the incisions. Selective removal of the compression sutures allows for a graded reduction in overcorrection. With this technique, a mean preoperative astigmatism in 10 patients of 14.25 diopters was reduced to 6.33 D 3 months postoperatively (P less than .002). There were no intraoperative or postoperative complications such as inadvertent perforation, wound dehiscence, or graft rejection.

  15. Opto-Mechanical Model of Arcuates for Astigmatism Correction. Low and High Order Aberrations

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    Navarro, Rafael; Palos, Fernando; Lanchares, Elena; Calvo, Begoña; Cristóbal, José Angel

    2011-01-01

    To develop a realistic model of the opto-mechanical behaviour of the cornea after curved relaxing incisions, and compare the astigmatism correction predicted by the model with that of the Lindstrom's nomogram. Methods: A three-dimensional finite element model of the anterior hemisphere of the ocular surface was generated, considering three parts: cornea, limbus and sclera. The corneal tissue was modeled as a quasiincompressible, anisotropic hyperelastic constitutive behaviour s...

  16. Pterygium surgery with conjunctival autograft and induced astigmatism in young men

    OpenAIRE

    Hüseyin Mayalı

    2012-01-01

    Objectives: To evaluate the results obtained from malesubjects who underwent pterygium surgery with conjunctivalautograft and to calculate the induced astigmatism.Materials and methods: Pterygium surgery with conjunctivalautograft was performed on 22 eyes of 20 subjectsdiagnosed with primary pterygium. If pterygium caused avision problem or approached the pupil level, and if surgerywas requested from the individuals for cosmetic reasons,the decision to operate was made. Patients who underwent...

  17. Pterygium surgery with conjunctival autograft and induced astigmatism in young men

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    Hüseyin Mayalı

    2012-09-01

    Full Text Available Objectives: To evaluate the results obtained from malesubjects who underwent pterygium surgery with conjunctivalautograft and to calculate the induced astigmatism.Materials and methods: Pterygium surgery with conjunctivalautograft was performed on 22 eyes of 20 subjectsdiagnosed with primary pterygium. If pterygium caused avision problem or approached the pupil level, and if surgerywas requested from the individuals for cosmetic reasons,the decision to operate was made. Patients who underwentany ocular surgery, have ocular surface disease,eyelid problems or systemic disease were not includedin the study. A complete ophthalmologic examination wasperformed before surgery, at one month following the surgery,and during the final controls. Induced astigmatismwas calculated by using refractive parameters and VectorialAnalysis Program.Results: Twenty-two eyes of 20 subjects were included inthe study. Mean age was 22.50 ± 4.15 (20-39 years. Allsubjects included in the study were male patients. Of the22 eyes, 14 were right and 8 were left eyes. In the evaluationsof visual acuity and intraocular pressure values preandpost- surgery, no statistical significance was detected(p=0.142, p=0.831. During the surgery, relapse was detectedin 4 eyes (18% and conjunctival granuloma (9%was detected in 2 eyes. Following the surgery, arithmeticaverage of the induced astigmatisms at 1st month was0.91±1.19 D; against-the-rule astigmatism was detectedin nearly 60% of the eyes. The subjects were followed upfor 93.59±36.47 days after the surgery.Conclusions: In primary pterygium subjects of youngage, surgery with conjunctival autograft was consideredas a preferable method due to its low number of relapseand complications, as well as absence of any adverse effecton visual acuity.Key words: Astigmatism, pterygium, young adult

  18. Air-pulse corneal applanation signal curve parameters for characterization of astigmatic corneas.

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    Trivizki, Omer; Shahar, Jonathan; Levinger, Samuel; Levinger, Eliya

    2014-07-01

    The aim of this study was to test the 42 parameters of the ocular response analyzer for distinguishing between the biomechanical properties of emmetropic eyes with normal topography and eyes with moderate-to-high with-the-rule astigmatism (WTA) and against-the-rule astigmatism (ATA) that have symmetric bowtie topography. This retrospective case series study included 37 patients (37 studied eyes) with WTA astigmatism and 35 patients (35 studied eyes) with ATA astigmatism. The control group consisted of 70 patients with emmetropia (70 studied eyes) with normal topography. We first tested correlations of the parameters that describe the applanation curve during ocular response analyzer measurements with the maximum keratometry values and the corneal thickness in all 3 groups. We then evaluated the significant parameters among them in search of any group differences in the biomechanical properties of the cornea. Fifteen parameters correlated with Kmax reading values or corneal thickness values. The correlation coefficients (r) were low. The best correlated parameters were p1area, p2area, h1, dive1, p2area1, h11, h2, and h21. The ATA group had the highest number of parameters (n = 6) with significant differences compared with the control group. Only p2area was predictive for ATA. In contrast, the WTA group had only 1 parameter (p2area1) that was found to be significantly different compared with the control group. Some of the new waveform parameters can distinguish between patients with ATA and WTA and normal topography patterns and may delineate the differences in biomechanical properties between these groups that may predict the risk of corneal ectasia after laser in situ keratomileusis.

  19. Ocular residual astigmatism: effects of demographic and ocular parameters in myopic laser in situ keratomileusis.

    Science.gov (United States)

    Frings, Andreas; Katz, Toam; Steinberg, Johannes; Druchkiv, Vasyl; Richard, Gisbert; Linke, Stephan J

    2014-02-01

    To analyze the influence of demographic and ocular factors on ocular residual astigmatism (ORA) in myopic laser in situ keratomileusis (LASIK). University Medical Center Hamburg-Eppendorf, Hamburg, Germany. Retrospective cross-sectional data analysis. Eyes of consecutive myopic patients scheduled for LASIK were studied to evaluate the influence on preexisting ORA of age, sex, ocular dominance, subjective cylinder and topographic astigmatism, subjective sphere, and mesopic pupil size. The ORA was determined using Alpins vector analysis. Two subgroups, defined by the ratio of ORA to preoperative refractive cylinder (R), were formed: ORA:R ≥ 1.0 and ORA:R patients). The mean ORA was 0.75 diopter (D) ± 0.39 (SD) (range 0.00 to 2.00 D); 1372 (46%) eyes had ORA of 1.00 D or more. Ordinary least square estimations and odds ratios showed that subjective sphere, male sex, and dominant eye were negative predictors of the degree of preoperative ORA, while increasing age and larger mesopic pupils did not indicate ORA orientation. With-the-rule astigmatism meridian was more likely in eyes with low ORA, while oblique and against-the-rule meridians were related to high ORA. The preoperative assessment of refractive surgery candidates should consider the interaction between topographic, refractive, and ORA because corneal refractive surgery is more successful in eyes in which the cylinder mainly originates from the anterior cornea. The current data can help identify patients at high risk for having a significant difference between subjective cylinder and topographic astigmatism. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  20. Arcuate keratotomy for high postoperative keratoplasty astigmatism performed with the intralase femtosecond laser.

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    Buzzonetti, Luca; Petrocelli, Gianni; Laborante, Antonio; Mazzilli, Emilio; Gaspari, Mario; Valente, Paola

    2009-08-01

    To evaluate the refractive and keratometric effect of arcuate keratotomy performed using the IntraLase femtosecond laser (Abbott Medical Optics) in patients with high postoperative keratoplasty astigmatism. Nine eyes of nine patients (mean age 45 +/- 7.5 years; mean spherical equivalent refraction -2.50 +/- 3.60 diopters [D]) who had undergone a penetrating keratoplasty were considered. The subjective refraction was measured, and corneal thickness and keratometric parameters were calculated by the Pentacam (Oculus Optikgeräte). All uncomplicated surgeries were performed with the IntraLase femtosecond laser. Paired 70 degrees arc length incisions were performed at 80% depth of the corneal thickness. The mean optical zone was 5.9 mm. The side cut was 90 degrees. All incisions were performed in the graft itself. Mean change in best spectacle-corrected visual acuity (BSCVA), refractive and keratometric astigmatism, and spherical equivalent refraction was evaluated. Follow-up was 3 months. Refractive and keratometric data were analyzed using vector analysis as described by Alpins. A paired Student t test was used to compare preoperative and 3-month postoperative data. A P value .05). The mean refractive astigmatism decreased by 6.00 D (P < .05), whereas the mean keratometric value decreased by 4.60 D (P < .05). The mean spherical equivalent refraction did not change significantly. The surgical vectors in the refractive and keratometric analysis were calculated, showing good predictability. Arcuate keratotomy performed with the IntraLase femtosecond laser could be an effective, safe, and relatively predictable treatment of high postoperative keratoplasty astigmatism.

  1. Clinical effects of rigid gas permeable contact lens in correcting high myopia and astigmatism

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    Ze-Hong Dong

    2015-02-01

    Full Text Available AIM: To evaluate the effect of rigid gas permeable contact lens(RGPin correcting high myopia and astigmatism. METHODS: Forty-one patients(65 eyeswith myopia(-9.03±6.19DS, maximum -23.00DSand astigmatism(-1.41±1.32DC, maximum -5.50DCwere fitted with RGP after strict routine ophthalmological examination, objective refraction and subjective refraction. All these patients were followed after 1wk, 1, 3mo and half one year. RESULTS: Sixty-five eyes were fitted with RGP(-9.92±5.96DS. RGP base curve(BCwas majorly located within the range 7.20~8.25mm. 46.2% eyes with RGP achieved 1.0(BCVAand 80.1% achieved above 0.6(BCVA. However, with spectacles, the percent was 28%(1.0and 60%(>0.6, respectively. BCVA of RGP was 0.81±0.22, but BCVA with spectacles was 0.66±0.28, there was statistical significance(PCONCLUSION: RGP effectively improves visual acuity of high myopia and astigmatism compared with spectacles.

  2. The use of the SoftPerm lens for the correction of irregular astigmatism.

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    Maguen, E; Caroline, P; Rosner, I R; Macy, J I; Nesburn, A B

    1992-07-01

    We evaluated the performance of the SoftPerm combined rigid gas permeable (RGP) and hydrogel lens for the visual correction of 49 eyes (30 patients) with irregular astigmatism. Follow-up was up to 15 months. An attempt was also made to compare the SoftPerm lens to its predecessor, the Saturn II lens. The most common etiology for irregular astigmatism was keratoconus. Others etiologies were penetrating keratoplasty and refractive surgery. Visual acuity improved significantly. Only two eyes were best corrected to 20/20 before fitting whereas, 13 eyes saw 20/20 after fitting. The rate of lens replacement was 0.22 lenses per eye per month. A variety of complications occurred, including corneal staining, abrasions, and edema. Complications also reflected the relative difficulty of handling of the lens, yet no vision threatening complications occurred. Overall, the SoftPerm lens is a vast improvement over the Saturn II and is a reasonable means of correction of irregular astigmatism.

  3. Lower- and higher-order aberrations predicted by an optomechanical model of arcuate keratotomy for astigmatism.

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    Navarro, Rafael; Palos, Fernando; Lanchares, Elena; Calvo, Begoña; Cristóbal, José A

    2009-01-01

    To develop a realistic model of the optomechanical behavior of the cornea after curved relaxing incisions to simulate the induced astigmatic change and predict the optical aberrations produced by the incisions. ICMA Consejo Superior de Investigaciones Científicas and Universidad de Zaragoza, Zaragoza, Spain. A 3-dimensional finite element model of the anterior hemisphere of the ocular surface was used. The corneal tissue was modeled as a quasi-incompressible, anisotropic hyperelastic constitutive behavior strongly dependent on the physiological collagen fibril distribution. Similar behaviors were assigned to the limbus and sclera. With this model, some corneal incisions were computer simulated after the Lindstrom nomogram. The resulting geometry of the biomechanical simulation was analyzed in the optical zone, and finite ray tracing was performed to compute refractive power and higher-order aberrations (HOAs). The finite-element simulation provided new geometry of the corneal surfaces, from which elevation topographies were obtained. The surgically induced astigmatism (SIA) of the simulated incisions according to the Lindstrom nomogram was computed by finite ray tracing. However, paraxial computations would yield slightly different results (undercorrection of astigmatism). In addition, arcuate incisions would induce significant amounts of HOAs. Finite-element models, together with finite ray-tracing computations, yielded realistic simulations of the biomechanical and optical changes induced by relaxing incisions. The model reproduced the SIA indicated by the Lindstrom nomogram for the simulated incisions and predicted a significant increase in optical aberrations induced by arcuate keratotomy.

  4. Corneal topography six years after photorefractive keratectomy for myopia and myopic astigmatism.

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    Serrao, Sebastiano; Lombardo, Giuseppe; Lombardo, Marco; Palombi, Marino; Roberts, Cynthia J

    2009-05-01

    To analyze the 6-year response of corneal topography to photorefractive keratectomy (PRK) for myopia and myopic astigmatism. Twenty patients (40 eyes) who had PRK using the Technolas Keracor 217C excimer laser platform were followed up to 6 years after surgery. The eyes were subdivided into three groups according to the preoperative spherical equivalent refraction and astigmatism component. Corneal topographic maps were obtained with a Placido disk topographer (Keratron Scout). The pre- and postoperative topographical data were imported into custom software, which computed the average composite corneal map and average difference map for each study group to quantify the anterior corneal changes following laser ablation. The software defined three concentric zones of the surface topography, allowing characterization of the regional corneal response following surgery. At 6 years, no changes in the surface topographic configuration of the central cornea were assessed following spherical myopic ablations in comparison with 1 year postoperatively. A slight peripheral flattening of approximately 0.60 diopters (D) (P < .001) was measured following the higher myopic ablations at 6 years compared with 1 year postoperatively. Minimal changes, of approximately 0.30 D (P < .001), in the anterior central cornea were observed following astigmatic correction during follow-up. Photorefractive keratectomy for the correction of myopia provides stable comeal topography, with no clinically significant changes in the curvature profile at 6 years after surgery.

  5. Oblique (off-axis) astigmatism of the reduced schematic eye with elliptical refracting surface.

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    Wang, Y Z; Thibos, L N

    1997-07-01

    The oblique (off-axis) astigmatism of the Indiana Eye, an aspheric reduced-eye model of ocular chromatic aberration and spherical aberration, is computed across the visual field by using Coddington's equations for nonspherical surfaces of revolution. Our results show that the amount of astigmatism varies significantly with the shape of the refracting surface and with the axial location of the pupil. For a pupil located 1.91 mm from the apex of the refracting surface (as originally specified for the model), the calculated Sturm's interval was larger than that reported in the literature. However, by moving the model's pupil 0.84 mm axially away from the apex toward the nodal point, a close match was achieved between Sturm's interval of the model eye and published data from human eyes for eccentricities up to 60 degrees. These results demonstrate that the aspheric reduced-eye model is capable of simultaneously accounting for the chromatic, spherical, and oblique astigmatic aberrations typically found in human eyes.

  6. Toric Intraocular Lens Implantation for Correction of Astigmatism in Cataract Patients with Corneal Ectasia

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    Efstratios A. Parikakis

    2013-11-01

    Full Text Available Our purpose was to examine the long-term efficacy of toric intraocular lens (IOL implantation in cataract patients with high astigmatism due to corneal ectasia, who underwent phacoemulsification cataract surgery. Five eyes of 3 cataract patients with topographically stable keratoconus or pellucid macular degeneration (PMD, in which phacoemulsification with toric IOL implantation was used to correct high astigmatism, are reported. Objective and subjective refraction, visual acuity measurement and corneal topography were performed in all cases before and after cataract surgery. In all cases, there was a significant improvement in visual acuity, as well as refraction, which remained stable over time. Specifically, in subjective refraction, all patients achieved visual acuity from 7/10 to 9/10 with up to -2.50 cyl. Corneal topography also remained stable. Postoperative follow-up was 18-28 months. Cataract surgery with toric IOL implantation seems to be safe and effective in correcting astigmatism and improving visual function in cataract patients with topographically stable keratoconus or PMD.

  7. Customized toric intraocular lens implantation for correction of extreme corneal astigmatism due to corneal scarring

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    R Bassily

    2010-03-01

    Full Text Available R Bassily, J LuckOphthalmology Department, Royal United Hospital, Combe Park, Bath, UKAbstract: A 76-year-old woman presented with decreased visual function due to cataract formation. Twenty-five years prior she developed right sided corneal ulceration that left her with 10.8 diopters (D of irregular astigmatism at 71.8° (steep axis. Her uncorrected visual acuity was 6/24 and could only ever wear a balanced lens due to the high cylindrical error. Cataract surgery was planned with a custom designed toric intraocular lens (IOL with +16.0 D sphere inserted via a wound at the steep axis of corneal astigmatism. Postoperative refraction was -0.75/+1.50 × 177° with a visual acuity of 6/9 that has remained unchanged at six-week follow-up with no IOL rotation. This case demonstrates the value of high power toric IOLs for the correction of pathological corneal astigmatism.Keywords: intraocular lens, corneal ulceration, visual acuity, scarring

  8. A novel nomogram for the treatment of astigmatism with femtosecond-laser arcuate incisions at the time of cataract surgery

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    Baharozian CJ

    2017-10-01

    Full Text Available Connor J Baharozian,1 Christian Song,2,3 Kathryn M Hatch,2,3 Jonathan H Talamo2,3 1Boston University School of Medicine, 2Massachusetts Eye and Ear Infirmary, 3Department of Ophthalmology, Harvard Medical School, Boston, MA, USA Purpose: The purpose of this study was to determine an arcuate incision (AI nomogram to treat astigmatism during femtosecond laser-assisted cataract surgery. Methods: This is a retrospective, cohort study. Femtosecond laser (FSL-assisted transepithelial AIs were created at a 9.0 mm optical zone, 80% depth, centered on the limbus. We modified the manual Donnenfeld limbal relaxing incision nomogram to 70% for with-the-rule (WTR, 80% for oblique (OBL, and 100% for against-the-rule (ATR astigmatism. The correction index (CI equaled AI-induced astigmatism/target-induced astigmatism. Measures included preoperative keratometric corneal cylinder (Pre Kcyl, postoperative Kcyl (Post Kcyl, and postoperative residual refractive astigmatism (Post RRA. Results: Mean Pre Kcyl and 1–2 months Post RRA in 161 eyes of 116 patients were 0.626±0.417 diopters (D (range 0.5–2 D, and 0.495±0.400 D (range 0–1.5 D, respectively. Mean absolute astigmatic changes (Pre Kcyl–Post Kcyl without accounting for axis change in the WTR, ATR, and OBL groups were 0.165±0.383 D (P<0.001, 0.374±0.536 D (P<0.001, and 0.253±0.416 D (P=0.02, respectively. Mean absolute astigmatic changes using RRA as the postoperative measurement (Pre Kcyl–Post RRA without accounting for axis change were 0.440±0.461 D (P<0.001, 0.238±0.571 D (P<0.05, 0.154±0.450 (P=0.111 in WTR, ATR, and OBL groups, respectively. CIs for WTR, ATR, and OBL were 0.53, 1.01, and 0.95, respectively. There were no intraoperative or postoperative complications related to the AIs.Conclusion: Transepithelial FSL-AIs using the modified Donnenfeld nomogram show potential for management of mild to moderate corneal astigmatism. An increase in the magnitude or reduction of the optical zone

  9. The use of WaveLight® Contoura to create a uniform cornea: the LYRA Protocol. Part 2: the consequences of treating astigmatism on an incorrect axis via excimer laser

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    Motwani M

    2017-05-01

    Full Text Available Manoj Motwani Motwani LASIK Institute, San Diego, CA, USA Purpose: To show how an incorrect manifest astigmatism axis can cause an abnormal induced astigmatism on a new axis. Patients and methods: Four eyes of three patients were treated primarily with WaveLight® EX500 wavefront optimized (WFO treatments for astigmatism. All four eyes needed enhancements and were analyzed retrospectively via WaveLight® Contoura to determine the reason for the incorrect astigmatism treatment. Two of the eyes were retreated with topographic-guided ablation, and two were treated with WFO correction. Results: The eyes that had an incorrect manifest axis resulted in a new abnormal induced astigmatism on a wholly new axis. Treatment with topographic-guided ablation completely eliminated the newly induced astigmatism. Treatment with WFO of an abnormal induced astigmatism corrected the refraction but still left topographic evidence of the abnormal astigmatism behind. One eye was incorrectly treated for astigmatism due to coma affecting refraction when the patient was dilated. This eye had a normal induced astigmatism on a perpendicular axis and was corrected using WFO. The use of manifest refraction with WaveLight® Contoura topographic-guided ablation will lead to incorrect astigmatism correction when the manifest astigmatism and axis differ from the WaveLight® Contoura measured. Conclusion: Correction of an incorrect manifest refraction astigmatic axis does not simply create undercorrection of the astigmatism but induces an entirely new abnormal astigmatism on a different axis. Manifest refraction is less accurate and can lead to abnormal astigmatism when laser ablation is performed. Keywords: WaveLight Contoura, astigmatism treatment, asymmetric astigmatism, topographic guide ablation, higher order aberrations, Contoura with LYRA Protocol, LASIK, PRK

  10. Correction of astigmatism after penetrating keratoplasty by relaxing incision with compression suture: a comparison between the guiding effect of photokeratoscope and of computer-assisted videokeratography.

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    Chang, Sheng-Ming; Su, Chuan-Yi; Lin, Chang-Ping

    2003-07-01

    To report the results of astigmatism correction after penetrating keratoplasty by relaxing incision with compression suture and to compare the guiding ability of a photokeratoscope with that of computer-assisted videokeratography. In the two independent retrospective series, 11 eyes received a relaxing incision with compression suture guided by photokeratoscope or computer-assisted videokeratography. In 22 eyes, the relaxing incision with compression suture showed a mean 56% reduction in astigmatism and 78% reduction in vector-calculated astigmatism. The mean postoperative visual acuity was improved 2.92 Landolt lines. The 11 eyes in which treatment was guided by photokeratoscope demonstrated a mean reduction of 50% and 71% in astigmatism and vector-calculated astigmatism, respectively, and visual acuity increased 2.44 Landolt lines. Another 11 eyes in which treatment was guided by computer-assisted videokeratography achieved a mean reduction of 67% and 90% in astigmatism and vector-calculated astigmatism, respectively, together with 3.41 Landolt lines improvement in visual acuity. There were no significant differences in astigmatism correction and visual acuity improvement between the two groups. The results demonstrate that the relaxing incision with compression suture is an effective and safe procedure for correcting high astigmatism after penetrating keratoplasty. The two instruments have no significant difference in their guiding capacities for this procedure.

  11. Vectorial astigmatic changes after corneal collagen crosslinking in keratoconic corneas previously treated with intracorneal ring segments: a preliminary study.

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    Piñero, David P; Alio, Jorge L; Klonowski, Pawel; Toffaha, Bader

    2012-01-01

    To analyze by means of a vectorial method the corneal astigmatic changes occurring after crosslinking (CXL) in keratoconic eyes and to determine the relationship between these changes and the final clinical outcome. A total of 16 eyes of 12 patients with the diagnosis of mild to moderate keratoconus and that underwent CXL surgery were included. All surgeries were performed using the standard technique with epithelial debridement. Visual, refractive, keratometric, corneal aberrometric, and corneal biomechanical changes were evaluated during a 24-month follow-up. Additionally, corneal astigmatic changes were analyzed using the Alpins vectorial method: targeted induced astigmatism (TIA), surgically induced astigmatism (SIA), difference vector (DV), magnitude of error (ME), flattening effect (FE), and torque (TRQ). No significant changes in refraction, central keratometry, and corneal higher order aberrations were detected during the follow-up (p ≥ 0.07). Corneal resistance factor increased at 6 months (p=0.05), but it decreased at 24 months (p = 0.01). Postoperatively, the magnitude of SIA vector was significantly lower than the TIA (p ≤ 0.04). Mean magnitude of DV was 3.33 ± 2.53 D at 24 months postoperatively. Mean ME remained negative during the follow-up (p ≥ 0.26). Mean magnitude of FE was also significantly lower than TIA at all postoperative visits (p ≤ 0.02). Mean magnitude of TRQ vector was 1.31 ± 1.41 D at 24 months. Significant negative correlations were found between corneal astigmatism preoperatively and postoperative ME and DV at all postoperative visits. Crosslinking is able to induce a corneal astigmatic change, but it is variable, not predictable, and insufficient to provide an effective astigmatic correction.

  12. Does the type of suturing technique used affect astigmatism after deep anterior lamellar keratoplasty in keratoconus patients?

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    Acar BT

    2011-04-01

    Full Text Available Banu Torun Acar, Ece Turan Vural, Suphi AcarHaydarpasa Numune Education and Research Hospital, Ophthalmology Clinic, Istanbul, TurkeyPurpose: To compare the effect of three different suturing techniques on astigmatism after deep anterior lamellar keratoplasty (DALK in patients with keratoconus.Methods: In this retrospective study, 54 eyes of 54 patients with advanced keratoconus underwent DALK with three suturing techniques: single running, interrupted running, and combined interrupted and running. Postkeratoplasty astigmatism was evaluated during examinations 1, 3, and 6 months postoperatively and 2 months after completing suture removal.Results: Twenty-four eyes had single running sutures, 16 eyes had interrupted sutures, and in 14 eyes the suturing technique used was combined interrupted and running sutures. Mean age was 25.6 ± 5.9 years, 27.3 ± 6.8 years, and 26.5 ± 5.7 years (P = 0.422, and postoperative astigmatism 1 month after surgery was 3.79 ± 1.19 D, 5.56 ± 1.78 D, and 4.21 ± 1.55 D in the three groups, respectively (P = 0.012. However, 2 months after completing the suture removal, final postoperative astigmatism was 3.43 ± 1.44 D, 3.87 ± 1.38 D, and 3.71 ± 1.46 D (P = 0.846. Final astigmatism less than 4 D was seen in 18 cases (75% in the single running group, nine cases (56.2% in the interrupted running group, and nine cases (64.2% in the combined interrupted and running group (P = 0.08.Conclusion: Postkeratoplasty astigmatism is comparable with three different suturing techniques used in patients with keratoconus after completing suture removal in DALK. Due to earlier suture removal in DALK, the type of suturing technique used is not considerably important.Keywords: astigmatism, deep anterior lamellar keratoplasty, suturing technique

  13. Profile of anisometropia and aniso-astigmatism in children: prevalence and association with age, ocular biometric measures, and refractive status.

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    O'Donoghue, Lisa; McClelland, Julie F; Logan, Nicola S; Rudnicka, Alicja R; Owen, Chris G; Saunders, Kathryn J

    2013-01-21

    We describe the profile and associations of anisometropia and aniso-astigmatism in a population-based sample of children. The Northern Ireland Childhood Errors of Refraction (NICER) study used a stratified random cluster design to recruit a representative sample of children from schools in Northern Ireland. Examinations included cycloplegic (1% cyclopentolate) autorefraction, and measures of axial length, anterior chamber depth, and corneal curvature. χ(2) tests were used to assess variations in the prevalence of anisometropia and aniso-astigmatism by age group, with logistic regression used to compare odds of anisometropia and aniso-astigmatism with refractive status (myopia, emmetropia, hyperopia). The Mann-Whitney U test was used to examine interocular differences in ocular biometry. Data from 661 white children aged 12 to 13 years (50.5% male) and 389 white children aged 6 to 7 years (49.6% male) are presented. The prevalence of anisometropia ≥1 diopters sphere (DS) did not differ statistically significantly between 6- to 7-year-old (8.5%; 95% confidence interval [CI], 3.9-13.1) and 12- to 13-year-old (9.4%; 95% CI, 5.9-12.9) children. The prevalence of aniso-astigmatism ≥1 diopters cylinder (DC) did not vary statistically significantly between 6- to 7-year-old (7.7%; 95% CI, 4.3-11.2) and 12- to 13-year-old (5.6%; 95% CI, 0.5-8.1) children. Anisometropia and aniso-astigmatism were more common in 12- to 13-year-old children with hyperopia ≥+2 DS. Anisometropic eyes had greater axial length asymmetry than nonanisometropic eyes. Aniso-astigmatic eyes were more asymmetric in axial length and corneal astigmatism than eyes without aniso-astigmatism. In this population, there is a high prevalence of axial anisometropia and corneal/axial aniso-astigmatism, associated with hyperopia, but whether these relations are causal is unclear. Further work is required to clarify the developmental mechanism behind these associations.

  14. Topography-guided transepithelial photorefractive keratectomy for irregular astigmatism using a 213 nm solid-state laser.

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    Allan, Bruce D; Hassan, Hala

    2013-01-01

    To explore the use of the Pulsar Z1 solid-state 213 nm photorefractive laser platform in topography-guided transepithelial photorefractive keratectomy (PRK) for irregular astigmatism. Moorfields Eye Hospital, London, United Kingdom. Prospective clinical case series. Patients with irregular astigmatism after previous refractive surgery or corneal transplantation were treated with topography-guided transepithelial PRK. Preoperatively and 1-year postoperatively, corrected distance visual acuity (CDVA) and secondary outcome measures (including manifest refraction, contrast sensitivity, haze score, index of surface variation, root-mean-square higher-order aberrations, and subjective visual change) were compared between groups. Adjunctive mitomycin-C was not used. Seven patients had previous refractive surgery, and 7 had previous corneal transplantation. All but 2 patients with a marked haze response had subjective gains in vision and improved CDVA. Gains in CDVA for patients with irregular astigmatism after previous refractive surgery (median 2 lines gain; range 0 to 2 lines gained) were higher than for patients with irregular astigmatism after keratoplasty (median 0 lines; range 5 lines lost to 4 lines gained). Trends in secondary outcome measures were similar, with greater variation in post-keratoplasty patients. Haze scores were higher in post-keratoplasty patients. 213 nm topography-guided transepithelial PRK was easy to perform and well tolerated by patients with irregular astigmatism. Most patients gained CDVA; however, increased haze responses were observed in post-keratoplasty cases. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  15. Changes in higher order aberrations after wavefront guided FS-LASIK for myopia combined with moderate to high astigmatism

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    Cang-Yu Guan

    2018-02-01

    Full Text Available AIM: To assess the changes in higher order aberrations after wavefront guided femtosecond laser assisted laser in situ keratomileusis(FS-LASIKfor moderate to high astigmatism. METHODS: Eighty-eight eyes of 50 myopia patients with moderate to high astigmatism were included in this prospective study. There were 51 eyes with moderate astigmatism(≥-1.50D and RESULTS: At the 3mo after operation, the mean UDVA of all eyes was above 20/20, better than before operation(PP=0.36and no eyes lost ≥2 lines of CDVA. Mean astigmstism of 85 eyes(97%was reduced below -1.00D, mean astigmatism of 70 eyes(80%was reduced below -0.50D(PPP=0.078, 0.065. The spherical aberration, secondary astigmatism and the HOA root mean square(RMSincreased from 0.19±0.06, 0.05±0.02 and 0.42±0.12, preoperatively to 0.32±0.17, 0.26±0.08 and 0.78±0.28(PCONCLUSION: Wavefront-guided FS-LASIK is a safe and effective option for the patients with moderate to high astigmstism although parts of HOAs increased.

  16. A unique astigmatic nodal property in misaligned Ritchey-Chrétien telescopes with misalignment coma removed.

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    Schmid, Tobias; Thompson, Kevin P; Rolland, Jannick P

    2010-03-01

    We present the aberration field response of Ritchey-Chrétien telescopes, with the aperture stop on the primary mirror, to secondary mirror misalignments. More specifically, we derive a general condition for the geometry of the binodal astigmatic aberration field for a telescope that has been aligned to remove field-constant coma. It has been observed that when the coma caused by secondary mirror misalignments is removed the astigmatic field is typically not symmetric around the periphery, but, significantly, it is always effectively zero on-axis. This observation is a manifestation of binodal astigmatism where one of the astigmatic nodes remains near the field center. Here, we show how the condition to remove field-constant coma simultaneously creates a constraint whereby one of the astigmatic nodes must remain effectively on-axis. This result points to why the alignment of a large telescope based on axial imagery is insufficient and demonstrates exactly the geometry of the remaining misalignment aberration field, which dominates the performance of the telescope, providing insights into more complete alignment approaches.

  17. Intrastromal corneal ring segment implantation to correct astigmatism after penetrating keratoplasty.

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    Coscarelli, Sandro; Ferrara, Guilherme; Alfonso, Jose F; Ferrara, Paulo; Merayo-Lloves, Jesús; Araújo, Luana P N; Machado, Aydano P; Lyra, João Marcelo; Torquetti, Leonardo

    2012-06-01

    To evaluate the clinical outcomes of implantation of Ferrara intrastromal corneal ring segments (ICRS) in patients with astigmatism after penetrating keratoplasty (PKP). Private clinic, Belo Horizonte, Brazil. Retrospective consecutive case series. Chart records of post-PKP patients who had ICRS implantation from May 2005 to September 2009 were retrospectively reviewed. The following parameters were studied: corrected distance visual acuity (CDVA), keratometry (K) values, spherical equivalent (SE), spherical refractive error, corneal topographic astigmatism, minimum K, and maximum K. The study evaluated 59 eyes (54 patients). The mean CDVA (logMAR) improved from 0.45 ± 0.17 (SD) (range 0.18 to 1.00) to 0.30 ± 0.17 (range 0.00 to 1.00). The mean SE was -6.34 ± 3.40 diopters (D) (range 0.37 to -16.50 D) preoperatively and -2.66 ± 2.52 D (range 0.87 to -10.50 D) postoperatively. The mean spherical refractive error decreased from -7.10 ± 3.07 D (range 2.15 to 16.68 D) preoperatively to -3.46 ± 2.05 D (range 0.88 to 10.79 D) postoperatively. No patient lost visual acuity. The mean corneal topographic astigmatism decreased from 3.37 ± 1.51 D preoperatively to 1.69 ± 1.04 D postoperatively. The mean maximum K value decreased from 48.09 ± 2.56 D to 44.17 ± 2.67 D and the mean minimum K value, from 44.90 ± 2.54 D to 42.46 ± 2.63 D. All changes were statistically significant (Pastigmatism after PKP. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  18. Effect of iris registration on outcomes of FEMTOLASIK for myopia and myopic astigmatism.

    Science.gov (United States)

    Ghoreishi, Mohammad; Beni, Zahra Naderi; Beni, Afsaneh Naderi; Kianersi, Farzan

    2017-09-05

    To compare the visual and refractive outcomes after FEMTOLASIK with and without iris registration. In this randomized, prospective, comparative, contralateral eye study, 118 eyes of 59 patients with myopia and myopic astigmatism underwent LASIK using the Femto LDV femtosecond laser (160 µm) and the MEL80 with or without iris registration. For each patient, iris registration FEMTOLASIK was performed on one eye and non-iris registration FEMTOLASIK was performed on the other eye, assigned at random. Patients were evaluated before and 12 months. Uncorrected visual acuity, best-corrected visual acuity, manifest refraction, contrast sensitivity, and higher-order aberrations (HOAs) were evaluated. At 12 months, the mean UDVA was 0.002 ± 0.07 logMAR (20/19) in iris registration eyes and 0.00 ± 0.06 logMAR (20/24) in non-iris registration eyes (P = 0.9). 61% of iris registration eyes and 71.2% of non-iris registration eyes achieved a UDVA of 20/20 or better (P = 0.31); 98.3% of eyes with the iris registration FEMTOLASIK and 94.9% with the non-iris registration FEMTOLASIK were within ±0.50 D from emmetropia (P = 0.71). No statistically significant difference was found in postoperative contrast sensitivity between groups at 3, 6, 12, or 18 cycles/degree (P > 0.05). There was significant increase in total HOA root mean square in two groups. The mean error magnitude of surgically induced astigmatism 12 months postoperatively was -0.33 in iris registration eyes and -0.24 in the non-iris registration eyes (P = 0.36). FEMTOLASIK with and without iris registration provides similar results in myopic and myopic astigmatism patients.

  19. Treatment of postoperative keratoplasty astigmatism using femtosecond laser-assisted intrastromal relaxing incisions.

    Science.gov (United States)

    Wetterstrand, Olli; Holopainen, Juha M; Krootila, Kari

    2013-06-01

    To investigate the effectiveness of femtosecond laser-assisted intrastromal relaxing incisions for astigmatism management and establish laser treatment parameters. Sixteen eyes of 16 patients had regular astigmatism after penetrating keratoplasty. All sutures had been removed and the refraction was stabilized. Paired arcuate intrastromal incisions were made 180° apart within the graft stroma with a femtosecond laser preserving the epithelium. Follow-up examinations were performed at 1 week, 2 weeks, 1 month, and 3 months. The logMAR corrected distance visual acuity (CDVA) improved from 0.50 ± 0.29 to 0.32 ± 0.23 (Snellen 20/63 to 20/40). Refractive and topographic anterior cylinders decreased from 6.8 ± 2.2 diopters (D) to 3.7 ± 1.7 D and from 9.5 ± 4.8 D to 4.4 ± 2.1 D, respectively. Stabilization of topographic cylinder was observed 1 month postoperatively. The worse the preoperative CDVA was and the higher the preoperative values for the refractive and topographic cylinders were, the higher the surgically induced changes were. Anterior side cut angles at 90° and 120° produced similar results. A bulge of incision occurred in one eye requiring compression sutures. Significant improvement in CDVA and refractive and topographic cylinders indicated a good effect of femtosecond laser-assisted intrastromal relaxing incisions in reducing astigmatism. No advantage between 90° and 120° anterior side cut angles was found. No infections were recorded and no patient expressed discomfort. Copyright 2013, SLACK Incorporated.

  20. Implantation of three-piece silicone toric additive IOLs in challenging clinical cases with high astigmatism.

    Science.gov (United States)

    Thomas, Bettina C; Auffarth, Gerd U; Reiter, Josef; Holzer, Mike P; Rabsilber, Tanja M

    2013-03-01

    To analyze the refractive outcomes and safety of three-piece silicone toric sulcus-fixated add-on intraocular lenses (IOLs) (HumanOptics/Dr.Schmidt Intraocularlinsen, Erlangen, Germany) in complex clinical cases with high astigmatism such as in cases with previous penetrating keratoplasty. Interventional case series of 21 eyes of 20 patients enrolled at two German centers. Functional results including power vector analysis, accuracy of IOL power calculation, rotational stability, and postoperative complications were evaluated from 2 months to 6 years postoperatively. The preoperative subjective cylinder exceeded or was equal to -6.00 diopters (D) in 81% of eyes (range: -2.00 to -17.00 D). The median follow-up period was 7.6 months (range: 57 days to 6 years). The efficacy analysis focused on the 2 to 6 months follow-up visit. Postoperatively, there was a median reduction of astigmatism by 70.59% (subjective cylinder range: 0.00 to -5.00 D), improvement of uncorrected distance visual acuity, and unchanged median corrected distance visual acuity. The attempted spherical equivalent was achieved within ± 0.50 D in 45% and within ± 1.00 D in 65% of cases. Five eyes received secondary surgical alignment of axis. Other complications related to the surgical procedure were mainly transient shortly after implantation, such as intraocular pressure elevation (2 of 21 eyes) or corneal edema (2 of 21 eyes). Persisting changes were seen only in rare cases and included pigment dispersion (1 of 21 eyes) or corneal edema requiring a second keratoplasty within 9 months after surgery (2 of 21 eyes). Toric add-on IOLs may be useful in reducing high astigmatism and anisometropia and increasing spectacle independence even in complex clinical conditions with high refractive errors. Copyright 2013, SLACK Incorporated.

  1. LASIK and PRK in hyperopic astigmatic eyes: is early retreatment advisable?

    OpenAIRE

    Frings A; Richard G; Steinberg J; Druchkiv V; Linke SJ; Katz T

    2016-01-01

    Andreas Frings,1 Gisbert Richard,1,2 Johannes Steinberg,1,3,4 Vasyl Druchkiv,1,4 Stephan Johannes Linke,1,3,4 Toam Katz1,4 1Department of Ophthalmology, University Medical Centre Hamburg-Eppendorf, 2Ophthalmologikum an der Alster, 3zentrumsehstärke, 4CARE Vision Germany GmbH, Hamburg, Germany Purpose: To analyze the refractive and keratometric stability in hyperopic astigmatic laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) during the first 6 mont...

  2. Wedge resection for high astigmatism after penetrating keratoplasty for keratoconus: refractive and histopathologic changes.

    Science.gov (United States)

    de la Paz, María Fideliz; Sibila, Gimena Rojas; Montenegro, Gustavo; de Toledo, Juan Alvarez; Michael, Ralph; Barraquer, Rafael; Barraquer, Joaquin

    2010-06-01

    To analyze the refractive, topographic, keratometric changes and the histopathologic findings after wedge resection to correct high astigmatism after penetrating keratoplasty for keratoconus. A retrospective study was done analyzing the following parameters preoperatively and at 1, 3, and 5 years postoperatively: uncorrected visual acuity, best-corrected visual acuity, and spherical equivalent and refractive, topographic, and keratometric cylinder measures. We also studied the efficacy and safety indices, as well as the histopathologic findings of tissues submitted for pathology. A total of 22 eyes of 21 patients who underwent wedge resection in the host corneal tissue for correcting high irregular astigmatism after penetrating keratoplasty for keratoconus were included in the study. Mean follow-up time from penetrating keratoplasty to wedge resection was 18 years, whereas the mean follow-up time after wedge resection was 39.04 months (range, 12-280 months). The mean preoperative refractive, topographic, and keratometric cylinders were 11.58 +/- 3.52 diopters (D) (range, 4.5-20 D), 10.88 +/- 5.03 D (range, 2.58-21.3 D), and 11.29 +/- 4.33 D (range, 4.50-18 D), respectively. The mean postoperative refractive, topographic, and keratometric cylinders at 3 years were 4.91 +/- 2.48 D (range, 0.50-10 D), 3.38 +/- 2.10 D (range, 2.05-7.1 D), and 5.31 +/- 2.90 D (range, 0.50-9 D), respectively. The percentage of correction at 3 years of follow up was 57.5% for refractive cylinder, 68.97% for topographic cylinder, and 53.01% for keratometric cylinder. All refractive, topographic, and keratometric data showed the lowest degree of astigmatism at 3 years postoperatively, with a tendency toward regression at 5 years postoperatively. Safety index was 1.0, whereas efficacy index was 0.49. All histopathologic sections of resected tissue were consistent with keratoconus progression in the host peripheral cornea. Wedge resection is a safe and moderately effective procedure in the

  3. Femtosecond laser arcuate keratotomy for the correction of high astigmatism after keratoplasty.

    Science.gov (United States)

    Nubile, Mario; Carpineto, Paolo; Lanzini, Manuela; Calienno, Roberta; Agnifili, Luca; Ciancaglini, Marco; Mastropasqua, Leonardo

    2009-06-01

    To determine the feasibility and initial outcomes of using a femtosecond laser to perform arcuate keratotomies to correct high post-keratoplasty astigmatism. Prospective noncomparative interventional case series. Twelve eyes of 12 consecutive patients (mean age 44.9+/-9.5 years) who presented with a high degree of astigmatism, noncorrectable with spectacles or contact lenses (10 post-penetrating keratoplasty, 2 post-deep lamellar keratoplasty), and were candidates for relaxing incisional corneal surgery. The Femtec (20/10 Perfect Vision, GmbH, Heidelberg, Germany) femtosecond laser performed paired 90-degree angled arcuate incisions on the graft button. The incision sites and depths were programmed at 1.00 mm inside the graft edge and at 90% of the corresponding local graft thickness, whereas the angular lengths of the cuts were determined by analyzing the locations and extents of the steepest meridians in the topographic map. Changes in uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), mean subjective and topographically determined astigmatism; imaging of incisions by anterior segment optical coherence tomography (AS-OCT); and wound healing by in vivo confocal microscopy (IVCM). Postoperative follow-up extended to 6 months. Mean uncorrected logarithm of the minimum angle of resolution (logMAR) BSCVA and UCVA improved from preoperative values of 0.25+/-0.16 and 1.05+/-0.18 to 6-month values of 0.11+/-0.12 (standard deviation) and 0.55+/-0.34, respectively (Pastigmatism was 7.16+/-3.07 diopters (D) preoperatively and 2.23+/-1.55 D at 1 month after surgery (P = 0.002) and remained stable to the end of follow-up. Anterior segment optical coherence tomography image analysis showed that the depth and location of the incisions were consistent with the preoperative surgical plan. In vivo confocal microscopy showed mild edema and keratocyte activation along the incision edges, together with initial epithelial ingrowth inside the wound

  4. Enhanced 3D localization of individual RNA transcripts via astigmatic imaging

    Science.gov (United States)

    Perillo, Evan P.; De Haro, Leyma; Phipps, Mary E.; Martinez, Jennifer S.; Yeh, Hsin-Chih; Dunn, Andrew K.; Shepherd, Douglas P.; Werner, James H.

    2014-03-01

    Here we present an automated microscope capable of 3D multi-color single molecule localization of individual messenger RNA molecules in a wide range of cell types. We have implemented astigmatic imaging with a cylindrical lens to improve z-localization, and a maximum likelihood estimator on a graphics processing unit to improve localization precision and speed. This microscope will aid in gene expression analysis by its capability to perform high throughput imaging of thick cells and tissues while still maintaining sufficient z resolution to resolve single RNA transcripts in three dimensions. Enhanced z-localization allows for resolving membrane localized and co-localized transcripts.

  5. Deep lamellar endothelial keratoplasty visual acuity, astigmatism, and endothelial survival in a large prospective series.

    Science.gov (United States)

    Terry, Mark A; Ousley, Paula J

    2005-09-01

    To report the 6-month results for the treatment of endothelial dysfunction in a large, prospective series of deep lamellar endothelial keratoplasty (DLEK) procedures. Prospective, noncomparative, interventional case series. One hundred eyes of 88 patients with corneal edema from Fuchs' dystrophy and pseudophakia. A limbal, scleral, partial-depth incision provided access for a deep lamellar corneal pocket dissection. Two eyes were converted to penetrating keratoplasty (PK) at the time of DLEK surgery because of poor dissections. Of the 98 eyes that had completed DLEK surgeries, 36 eyes received a large-incision technique (9-mm scleral access incision) and 62 eyes received a small-incision technique (5-mm scleral access incision). A 7.5- to 8.0-mm posterior lamellar disc of recipient tissue then was excised and replaced through the pocket with a similar size donor disc containing healthy endothelium. A temporary air bubble in the anterior chamber was used for donor tissue adherence, and no surface corneal incisions or sutures were necessary. Preoperative and postoperative best spectacle-corrected visual acuity (BSCVA), manifest refraction (MR) astigmatism, and endothelial cell density (ECD) were evaluated prospectively. At 6 months after surgery, all 98 DLEK corneas were clear and the grafts were healed in good position. The mean BSCVA was 20/46, with a range between 20/20 and 20/400. The average MR astigmatism was 1.34+/-0.86 diopters (D), representing an average change in astigmatism from before surgery of +0.28+/-1.08 D (P = 0.013). The average ECD at 6 months was 2140+/-427 cells/mm2, representing a mean cell loss from preoperative donor cell measurements of 25%. The DLEK procedure, with its absence of corneal surface incisions and sutures, preserves the normal corneal topography, minimizes astigmatism, and provides a healthy donor endothelial cell count and function. The DLEK procedure represents a reasonable alternative to PK, and compared with historical PK

  6. Optimization of the optical performance of variable-power and astigmatism Alvarez lenses.

    Science.gov (United States)

    Peloux, Marius; Berthelot, Laurent

    2014-10-10

    We first explore the operating principle and optical performances of dioptric-power and astigmatism-variation lens doublets based on the L. W. Alvarez design. These fall within the scope of two ophthalmic applications: ophthalmic glasses for the correction of presbyopia, taking into account any type of ametropia, and spherocylindrical refractors. Second, we present a multiconfiguration optimization method leading to improved optical performances of such doublets over a wide field of view. We then investigate the particular distribution of the curvature on the complex surfaces of the two lenses after optimization.

  7. Corneal perforation by an astigmatic keratotomy performed with an optical coherence tomography-guided femtosecond laser.

    Science.gov (United States)

    Cherfan, Daniel G; Melki, Samir A

    2014-07-01

    We present a case of corneal perforation secondary to an intrastromal astigmatic keratotomy performed with an optical coherence tomography-guided femtosecond laser. The keratotomy was concomitant with cataract surgery and resulted in a flat anterior chamber prior to the start of lens extraction. Interrupted nylon sutures were placed to seal the keratotomy prior to phacoemulsification. Escape of cavitation bubbles into the anterior chamber or the liquid interface can alert the surgeon to the possibility of unintended perforation of the endothelium or the epithelium, respectively. Neither author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  8. Compressive C-shaped lamellar keratoplasty: a surgical alternative for the management of severe astigmatism from peripheral corneal degeneration.

    Science.gov (United States)

    Cheng, Ching-Li; Theng, Julian T S; Tan, Donald T H

    2005-03-01

    To describe a compressive lamellar surgical technique for treating severe astigmatism in peripheral corneal ectasia. Retrospective, noncomparative, interventional case series. Four eyes of 3 patients with either pellucid or Terrien's marginal corneal degeneration were included in this series. C-shaped lamellar keratoplasty using multiple trephines of different sizes, with deliberate undersizing of the donor graft for a controlled compressive effect, was performed on these patients. Visual acuity outcome and refraction were measured at different intervals at up to 40 months of follow-up. All eyes achieved Snellen visual acuity of 20/40 or better and stable astigmatism ranging from 0 to -2.75 diopter cylinder within 6 months, with no recurrence of corneal thinning or peripheral corneal vascularization. Compressive C-shaped lamellar keratoplasty is able to reduce severe corneal astigmatism in peripheral corneal ectasia and can result in good visual and refractive outcomes with early visual rehabilitation.

  9. Comparison of clinical outcomes between limbal relaxing incisions and toric intraocular lenses in eyes with astigmatic corneas

    Directory of Open Access Journals (Sweden)

    Giuliano de Oliveira Freitas

    2014-01-01

    Full Text Available Objective: To compare refractive and vectorial outcomes of limbal relaxing incisions (LRI versus toric intraocular lenses (IOL in the treatment of preexisting corneal astigmatism at the time of phacoemulsification. Methods: This longitudinal observational case series assessed 62 eyes of 31 consecutive cataract patients with preoperative corneal astigmatism between 0.75 and 2.50 diopters in both eyes. Patients were randomly assorted in two groups: one assigned to receive AcrySof Toric™ IOL in both eyes, and another one assigned to have AcrySof Natural™ IOL associated with LRI, also in both eyes. All patients were re-evaluated, postoperatively, at 1, 3 and 6 months, when refractive astigmatism analysis was performed using vectorial methods proposed by Thibos. Variability of outcomes within each group and between groups were assessed and compared. Results: Manifest refractive cylinder, in diopters (D, as means ± standard deviation, in the LRI group for 1-month, 3-month and 6-month re-evalutions were respectively -0.66 ± 0.30; -0.70 ± 0.21 and -0.74 ± 0.26 when compared to -0.58 ± 0.24; -0.63 ± 0.20, and -0.62 ± 0.17 in the toric IOL group. (p value ≥ 0.06. Vectorial analysis evidenced greater astigmatism reduction in the toric IOL group in the 6th postoperative month, when postoperative mean astigmatic power vector was 0.31 D, when compared to 0.37 D in the LRI group (p value = 0.00. Conclusions: A trend of slightly better refractive outcomes favoring toric IOL group was seen, although such a trend was not statistically significant. Vectorial analysis, however, suggests that the use of toric IOL may constitute a more advantageous approach in the treatment of pre-existing corneal astigmatism, simultaneously with phacoemulsification.

  10. The Results of Toric Intraocular Lens Implantation in Patients With Cataract and High Astigmatism After Penetrating Keratoplasty.

    Science.gov (United States)

    Müftüoğlu, İlkay Klç; Akova, Yonca Aydn; Egrilmez, Sait; Yilmaz, Suzan Guven

    2016-03-01

    To evaluate the results of toric intraocular lens (IOL) implantation in patients with cataract and postpenetrating keratoplasty astigmatism. Seven eyes of 7 patients with cataract and more than 3.5 diopters (D) astigmatism following penetrating keratoplasty were included in this retrospective case series study. All of the eyes underwent phacoemulsification and Acrysof toric IOL (t5-t9) implantation at least 6 months later than the complete suture removal. Corrected visual acuity (CVA), manifest astigmatism, the keratometry measurements, and complications were assessed. The mean preoperative CVA significantly increased (0.7±0.3 [range: 0.3-1.3] logMAR to 0.1±0.04 [range: 0.05-0.15] logMAR; Pastigmatism and the average manifest refractive astigmatism at the last visit were 5.4±0.9 D (range: 4.25-7 D) and 1.6±0.6 D (range: 0.5-2.5 D), respectively. The mean attempted cylinder correction at spectacle plane was 4.3±0.9 D (range: 2.4-4.7 D) whereas the mean cylinder correction was 4.6±0.5 D (range: 3.9-5.9 D), showing a slightly tendency for overcorrection. All eyes (100%) were within 1 D of predicted residual astigmatism. No complication occurred during the follow-up. Toric IOL implantation seems to be an effective, predictable, and safe procedure in patients with cataract formation and high astigmatism after penetrating keratoplasty.

  11. Arcuate keratotomy on post-keratoplasty astigmatism is unpredictable and frequently needs repeat procedures to increase its success rate.

    Science.gov (United States)

    Bayramlar, Huseyin; Karadag, Remzi; Cakici, Ozgur; Ozsoy, Isilay

    2016-06-01

    To evaluate the effectiveness and predictability of arcuate keratotomy (AK) for post-keratoplasty astigmatism and to present the complications and rate of repeat procedures. Sixteen eyes from 14 patients were included. Paired 70-80° arc length AKs centred on the steep axis were carried out 0.5 mm within the graft-host junction. The depth of the AKs was set at approximately 80-90% of the depth of the cornea, based on a topographic pachymeter at the incision location. The outcome measures included preoperative and postoperative topographic astigmatism, uncorrected and corrected visual acuity, surgical complications and repeat procedures. In 12 of the 16 eyes (75%), at least one additional surgical procedure was required to obtain the desired result: suturing for overcorrection or wound gape in six eyes (38%), lengthening of the incisions for undercorrection in four eyes (25%) and additional AKs for marked astigmatic axis displacement in three eyes (19%). The mean preoperative astigmatism was 10.45±3.82 dioptres (D); the postoperative astigmatism at the last visit was 2.99±1.14 D (in a mean follow-up of 17.6±5.55 months). The efficacy index was 0.83 and the safety index was 1.68. In treatment of post-keratoplasty astigmatism, AK does not have a good predictability. Additional procedures such as lengthening of the AK incisions for undercorrection or using compression sutures for overcorrection with significantly gaping wounds are frequently required to improve the final outcome. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  12. Mode-coupling enhancement by pump astigmatism correction in a Ti:Sapphire femtosecond laser.

    Science.gov (United States)

    Ramírez-Guerra, Catalina; Moreno-Larios, José Agustín; Rosete-Aguilar, Martha; Garduño-Mejía, Jesús

    2016-12-01

    To pump a solid-state femtosecond laser cavity, a beam from a CW laser is focused by a single lens into the laser crystal. To increase the output power of the laser, the overlap of the laser mode with the pump mode should be maximized. This is particularly important in the so-called mode coupling and the Kerr-lens mode locking (KLM) operation, where the change in beam waist at the position of the gain medium is exploited to enhance the mode overlap with the pump laser in the crystal. In this paper, the astigmatism in the pump beam is reduced by tilting the pump lens. A Gaussian beam is propagated through the complete focusing system-pump lens, tilted spherical mirror, and crystal cut at Brewster's angle-to show the astigmatism inside the crystal as a function of the tilt of the pump lens. A genetic algorithm is presented to optimize the mode coupling between the pump and laser beam inside the crystal by tilting the pump lens. Experimental results are presented to verify the design, showing an increase in the output power of the laser cavity of about 20%.

  13. Keratoconus-integrated characterization considering anterior corneal aberrations, internal astigmatism, and corneal biomechanics.

    Science.gov (United States)

    Alió, Jorge L; Piñero, David P; Alesón, Alicia; Teus, Miguel A; Barraquer, Rafael I; Murta, Joaquim; Maldonado, Miguel J; Castro de Luna, Gracia; Gutiérrez, Ramón; Villa, César; Uceda-Montanes, Antonio

    2011-03-01

    To evaluate the clinical features of keratoconus taking into consideration anterior corneal aberrations, internal astigmatism, and corneal biomechanical properties and to define a new grading system based on visual limitation. Vissum Corporation, Alicante, Spain. Retrospective case series. This multicenter study comprised consecutive keratoconic eyes with no previous ocular surgery or active ocular disease. Visual, refractive, corneal topography, and pachymetry outcomes were analyzed. Internal astigmatism was calculated by vectorial analysis. Corneal aberrations and corneal biomechanics characterized by the Ocular Response Analyzer were evaluated in some eyes. Correlations between clinical data and a linear multiple regression analysis for characterizing the relationship between visual limitation and objective clinical data were performed. This study comprised 776 eyes of 507 patients (age range 11 to 79 years) The mean keratometry (K) correlated significantly with logMAR corrected distance visual acuity (CDVA) (r = 0.591, Paberrations between 4 groups differentiated by visual limitation (Pcorneas and allowed development of a new grading system for this condition. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  14. Clinical studies of fully automatic computer optometry to test children astigmatism and the change of axial

    Directory of Open Access Journals (Sweden)

    Xiao-Zhen Huang

    2015-06-01

    Full Text Available AIM: To observe and analyze the detection results of child astigmatism before and after cycloplegia and axial changes by using computer automatic refractometer. METHODS:Sixty cases(120 eyeswith anisometropia founded by subjective optometry were selected as the research object. According to age, they were divided into 3~6 years groups(14 cases, 28 eyes, 7~9 years group(29 cases, 58 eyesand 10~12 years group(17 cases, 34 eyes. Three groups of patients were given compound tropicamide eye drops for mydriasis. Using automatic computer refractor detected spherical degree, cylinder diopters, astigmatism axis of all patients and made self-control analysis.RESULTS: Spherical degree and cylinder diopters before and after cycloplegia had statistical difference in children of all ages(PP>0.05. After cycloplegia, by camparing the result of automatic computer integrated refractometer and that of inspection shadow optometry, the coincidence rate of spherical, cylinder diopter in 3~6 years group was lower than that of 7~9 years group and 10~12 years group.CONCLUSION: After cycloplegia, fully automatic computer refractometer can more accurately obtain diopter, easy to operate, has more coincidence rate with optometry. It can be use as prescription basis for children aged 3~12 years.

  15. Irregular Astigmatism After Corneal Transplantation--Efficacy and Safety of Topography-Guided Treatment.

    Science.gov (United States)

    Laíns, Inês; Rosa, Andreia M; Guerra, Marta; Tavares, Cristina; Lobo, Conceição; Silva, Maria F L; Quadrado, Maria J; Murta, Joaquim N

    2016-01-01

    To analyze the efficacy and safety of topography-guided photorefractive keratectomy (TG-PRK) to treat irregular astigmatism after corneal transplantation. This was a retrospective observational case series. Eyes with irregular astigmatism after penetrating keratoplasty treated with TG-PRK (Allegretto Wave Eye-Q) with the topography-guided customized ablation treatment protocol were included. All treatments had been planned to correct the topographic irregularities, as well as to reduce the refractive error after neutralizing the induced refractive change. Clinical records, treatment plan, and the examinations performed were reviewed and the following data were collected: corrected and uncorrected distance visual acuities; manifest refraction; topographic parameters, and corneal endothelial cell count. We included 31 eyes [30 patients; mean age 45.0 ± 13.4 (SD) years]. At the last postoperative follow-up (mean 9.2 ± 8.2 months), we observed a significant improvement in corrected (P = 0.001) and uncorrected distance visual acuities (P transplantation eyes. Our results confirm that TG-PRK is an efficient treatment, associated with significant improvements of both visual acuity and refractive parameters.

  16. Effectiveness of cataract phacoemulsification with toric intraocular lenses in addressing astigmatism after keratoplasty.

    Science.gov (United States)

    Lockington, David; Wang, Ellen F; Patel, Dipika V; Moore, Sacha P; McGhee, Charles N J

    2014-12-01

    To assess the effectiveness of toric intraocular lenses (IOLs) in the management of post-keratoplasty astigmatism. Public university hospital, Auckland, New Zealand. Retrospective case series. The study analyzed post-keratoplasty eyes after cataract surgery and toric IOL (Acrysof SN60AT or T-flex 623T/573T) implantation. Twenty-six eyes were included. The mean age at cataract surgery was 57.1 years ± 11.2 (SD). Previous keratoplasty was penetrating (84.6%) or deep anterior lamellar (15.4%). Keratoconus (73.1%) was the major indication for keratoplasty. The mean IOL cylinder power was 6.85 ± 3.02 diopters (D). No IOL required postoperative realignment. The mean follow-up was 14 ± 11 months. The mean refractive spherical equivalent decreased significantly, from -3.67 ± 5.76 D to -0.58 ± 1.71 D (P=.01). The mean refractive astigmatism also decreased significantly, from -5.49 ± 3.72 D to -2.61 ± 2.10 D (Pastigmatism and improving visual acuity in a large cohort of post-keratoplasty eyes. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  17. Precut tissue for Descemet's stripping automated endothelial keratoplasty: vision, astigmatism, and endothelial survival.

    Science.gov (United States)

    Terry, Mark A; Shamie, Neda; Chen, Edwin S; Phillips, Paul M; Hoar, Karen L; Friend, Daniel J

    2009-02-01

    To report 6 and 12 month results using precut tissue for Descemet's stripping automated endothelial keratoplasty (DSAEK) and correlate donor characteristics with clinical outcomes. Prospective, noncomparative, interventional case series. We reviewed 100 donor corneas precut for 100 eyes of 90 DSAEK patients. Our first 100 consecutive cases of DSAEK with precut tissue were entered into a prospective protocol. Donor characteristics and the visual, refractive, topographic, and specular microscopy results at 6 and 12 months were analyzed. Correlation analysis comparing donor characteristics with clinical outcomes was performed. Six- and 12-month postoperative best spectacle-corrected visual acuity (BSCVA), refractive astigmatism, topographic keratometry (K), and specular endothelial cell densities (ECD) were measured prospectively and then compared with preoperative values. Donor characteristics analyzed included death to preservation time, death to surgery time, precutting resection to surgery time, and graft thickness. Six months after DSAEK surgery, BSCVA improved from 20/83 to 20/38. (P/=20/40 at 6 months and 20% obtained > or =20/20. Astigmatism changed an average of 0.09 diopters (D) and K changed by +0.09 D, both of which were not significant and were stable to 12 months. The postoperative mean ECD (n = 65) was 1918 cells/mm(2) at 6 months, and represented a 31% cell loss from preoperatively (Pastigmatism. Donor endothelial cell loss from 6 to 12 months is stable and is comparable with reports involving tissue that is cut intraoperatively. Proprietary or commercial disclosures may be found after the references.

  18. Numerical Methods Are Feasible for Assessing Surgical Techniques: Application to Astigmatic Keratotomy

    Energy Technology Data Exchange (ETDEWEB)

    Ariza-Gracia, M.A.; Ortilles, A.; Cristobal, J.A.; Rodriguez, J.F.; Calvo, B.

    2016-07-01

    The present study proposes an experimental-numerical protocol whose novelty relies on using both the inflation and the indentation experiments simultaneously to obtain a set of material parameters which accounts for both deformation modes of the cornea: the physiological (biaxial tension) and the non-physiological (bending). The experimental protocol characterizes the corneal geometry and the mechanical response of the cornea when subjected to the experimental tests using an animal model (New Zealand rabbit's cornea). The numerical protocol reproduces the experimental tests by means of an inverse finite element methodology to obtain the set of material properties that minimizes both mechanical responses at the same time. To validate the methodology, an Astigmatic Keratotomy refractive surgery is performed on 4 New Zealand rabbit corneas. The pre and post-surgical topographies of the anterior corneal surface were measured using a MODI topographer (CSO, Italy) to control the total change in astigmatism. Afterwards, the surgery is numerically reproduced to predict the overall change of the cornea. Results showed an acceptable numerical prediction, close to the average experimental correction, validating the material parameters obtained with the proposed protocol. (Author)

  19. Photorefractive keratectomy in the management of postradial keratotomy hyperopia and astigmatism

    Directory of Open Access Journals (Sweden)

    Mohammad Ghoreishi

    2017-01-01

    Full Text Available Background: The aim of this study is to evaluate the results of photorefractive keratectomy (PRK in the management of postoperative hyperopia and astigmatism in patients with history of radial keratotomy (RK. Materials and Methods: This prospective nonrandomized noncomparative interventional case series enrolled consecutive eyes treated with PRK after RK. In cases, in which (1 wavefront (WF scan was undetectable during primary examinations; and/or, (2 WF data were not transferable to the excimer laser device, patients were treated with the tissue-saving (TS mode. Patients with detectable/transferable WF were assigned to WF-guided advanced personalized treatment (APT. Results: Thirty-two and 47 eyes were managed by APT and TS modes, respectively. Pooled analysis of both APT and TS groups showed improvement in uncorrected distant visual acuity and corrected distant visual acuity. The amount of sphere, cylinder, corneal cylinder, spherical equivalent, defocus equivalent, and total aberration showed improvement as well. Conclusion: PRK seems to bring favorable outcome and safety profile in the management of post-RK hyperopia and astigmatism. It is crucial for practitioners to warn their patients about the fact that they may still have progressive refractive instability regardless of their choice on the laser method of vision correction.

  20. Combined intrastromal astigmatic keratotomy and laser in situ keratomileusis flap followed by photoablation to correct post-penetrating keratoplasty ametropia and high astigmatism: One-year follow-up.

    Science.gov (United States)

    Shalash, Riad B; Elshazly, Malak I; Salama, Marwa M

    2015-10-01

    To evaluate a new technique combining intrastromal astigmatic keratotomy (AK) with a laser in situ keratomileusis (LASIK) flap followed by excimer laser photoablation to correct post-penetrating keratoplasty (PKP) high astigmatism and ametropia. Kasr El Aini Hospital, Cairo University, Cairo, Egypt. Prospective interventional uncontrolled case series. Patients with post-PKP high astigmatism and ametropia had paired intrastromal AK with LASIK flap using the M2 microkeratome followed 2 to 3 months later by excimer laser photoablation. The main outcome measures were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), mean refractive spherical equivalent (SE), and mean cylinder after each step and at the 1-year follow-up. The study comprised 20 eyes (20 patients). All parameters were significantly improved in all patients by the last follow-up visit. The mean UDVA improved from 1.07 logMAR ± 0.2 (SD) preoperatively to 0.23 ± 0.18 logMAR (P astigmatism and ametropia following PKP; however, epithelial ingrowth requiring intervention is a complication to be considered. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  1. Corneal first-surface aberration analysis of the biomechanical effects of astigmatic keratotomy and a microkeratome cut after penetrating keratoplasty.

    Science.gov (United States)

    Kohnen, Thomas; Bühren, Jens

    2005-01-01

    Astigmatic keratotomy (AK) was performed in a patient after penetrating keratoplasty (PKP) for keratoconus to reduce high post-PKP astigmatism. The procedure led to a significant decrease in astigmatism, but corneal higher-order aberrations (HOAs) increased. After PKP, the patient was scheduled for 2-step laser in situ keratomileusis (LASIK) to correct myopia and astigmatism. One day after the microkeratome cut, a decrease of -2.75 diopters in the spherical equivalent (SE) was noted. Although subjective manifest cylinder and corneal spherical aberrations were marginally affected, a marked decrease in coma and other HOAs could be observed. One month after the cut, the SE was unchanged. Excimer laser ablation was not performed as the patient was satisfied with the result and refused further treatment. This case shows that AK cuts can induce HOAs and a single microkeratome cut performed in corneal grafts can have strong biomechanical effects on lower-order aberrations and HOAs. If LASIK is planned after PKP, a 2-step approach is recommended to anticipate biomechanical effects and avoid overcorrection or undercorrection.

  2. [Implantation of a sulcus-fixated toric additive intraocular lens in a case of high astigmatism after a triple procedure].

    Science.gov (United States)

    Linz, K; Auffarth, G U; Kretz, F T A

    2014-08-01

    Residual refractive errors, especially high-grade astigmatism after penetrating keratoplasty, often lead to a significant loss of vision. If high anismetropia could not be corrected with glasses or contact lenses, different kinds of surgical procedures are available for visual rehabilitation (intraocular lens exchange, astigmatic keratotomy, Excimer laser treatment, intrastromal corneal ring segment implantation and additive intraocular lens implantation). Toric add-on IOLs are especially designed for sulcus implantation and correcting high astigmatism in pseudophakic eyes. All toric IOLs are individually manufactured according to subjective refraction and biometry. Depending on the underlying manufacturer high-grade astigmatism can be corrected with a cylindrical power up to + 30.0 D. A 74-year-old patient presented with endothelial decompensation and an uncorrected distance visual acuity (UDVA) of 1.0 logMAR for penetrating keratoplasty on the right eye due to a Fuchs endothelial dystrophy. Postoperatively, the uncorrected distance visual acuity improved to 0.8 logMAR, with pinhole correction to 0.5 logMAR. After removing the sutures a high and irregular corneal astigmatism of 21.0 D was found. The corrected distance visual acuity (CDVA) with a refraction of + 5.5 D sph, - 21.0 D cyl 90° was 0.24 logMAR. Therefore an individually manufactured toric additive intraocular lens of + 25.0 D cylindrical and - 18.0 D spherical power for sulcus implantation was chosen and implanted uneventfully. Eight months after surgery refractive astigmatism was reduced significantly to - 0.75 D with an UDVA of 0.08 logMAR and a CDVA of 0.02 logMAR. During the 8-months follow-up period the additive IOL remained centered and no IOL rotation could be observed. Toric add-on IOLs are a safe and successful method for reducing high astigmatism and anisometropia after penetrating keratoplasty. One of the main advantages is the reversibility of the procedure by an explantation of

  3. Evaluation of Refractive Results of LASIK and LASEK in Patients with Myopia and Myopic Astigmatism

    Directory of Open Access Journals (Sweden)

    Okan Taşkın

    2014-10-01

    Full Text Available Objectives: To compare the mean visual acuity, spherical equivalent (SE, cylindrical refractive error, and central corneal thickness (CCT results of LASIK and LASEK in patients with myopia and myopic astigmatism. Materials and Methods: A retrospective review of the patients who underwent LASIK or LASEK for myopia or myopic astigmatism between 2008 and 2011 was performed in the Department of Ophthalmology at Dokuz Eylül University School of Medicine. Preoperative data collected were as follows: Mean SE, mean cylindrical refractive error, best-corrected visual acuity (BCVA, and mean CCT. Postoperative data included mean SE, uncorrected visual acuity (UCVA, mean CCT, and complications at 1, 3, and 6 months, as well as at the last control. The results in the LASIK group were compared to those in the LASEK group. Results: The both (LASIK and LASEK groups consisted of 60 eyes of 30 patients. All exams and surgeries were performed by one surgeon (ZO. The two groups were similar in terms of age and gender. Mean preoperative SE and BCVA values of the two groups were similar. The mean preoperative cylindrical refractive error values were significantly higher in the LASEK group (p=0.02. The mean preoperative CCT values were significantly lower in the LASEK group (p=0.0. At one month after the surgery, the mean SE and cylindrical refractive error values were not significantly different, but the mean UCVA values were significantly higher in the LASIK group (p=0.015. At six months, the mean SE, cylindrical refractive error, and UCVA values were not significantly different. The mean follow-up period was 13.4 (9-36 months months. Mean UCVA values at the last exam were higher than the preoperative mean BCVA values in both LASIK and LASEK groups. Conclusion: Both LASIK and LASEK are effective and safe procedures for correction of myopia and myopic astigmatism. The patients with normal corneal thickness and epithelium, normal lid aperture, and low trauma risk are

  4. INTRAOCULAR CORRECTION OF PRESBYOPIA BY MONOVISION IN PATIENTS WITH CATARACT AND CORNEAL ASTIGMATISM

    Directory of Open Access Journals (Sweden)

    E. I. Belikova

    2017-01-01

    Full Text Available Purpose: To evaluate the results of intraocular correction of presbyopia by monovision in patients with cataract and primary corneal astigmatism and conduct a comparative analysis of these outcomes with the results of binocular multifocal IOLs implantation. Patients and methods. There were 21 patients with bilateral cataract surgery performed using toric monofocal intraocular lenses (monovision group in the study. The indications for the operation were: 1 primary corneal astigmatism ≥ 1.0D in patients with cataract, 2 inability to conduct excimer laser correction. Reduction of spectacle dependence by monovision was discussed during preoperative conversation. The age of patients range from 32 to 65 years. Target refraction: Emetronopia on the dominant eye (DG and myopia at 1.0–2.0 D in the non-dominant eye (NDG. Evaluation included measurement of uncorrected visual acuity, refraction, stereopsis, contrast sensitivity and patient satisfaction. The results were compared with the outcomes of binocular multifocal Iols implantation in 22 patients (44 eyes. Results. The spherical component decreased from 3.39±2.63D to 0.34±0.24D, cylinder decreased from 3.05±1.47D to 0.44±0,35D (P <0.01 in the monovision group three months after surgery . The deviation from target refraction was 0.30±0.35D. The mean difference between postoperative refraction on the two eyes was 1.92±0.57D. Postoperative corrected visual acuity significantly exceeded preoperative parameters. In 18 patients (88% the stereoscopic visual acuity did not exceed 60 seconds and corresponded to the age norm, in 3 patients (12% it was at the level of 80–100 arc seconds. In patients with multifocal IOLs, the stereovision values were identical (Ferrer-Blasco T. et al, 2008. Conclusion. The monovision is an effective method of reducing dependence on additional correction in patients with cataract and corneal astigmatism. Refractive outcomes, binocular visual acuity, predictability and

  5. [Reduction of astigmatism by 4mm long sutureless corneal cataract incision (stretch incision) with phacoemulsification and 5mm PMMA lens implantation].

    Science.gov (United States)

    Müller-Jensen, K; Schüler, M

    1998-06-01

    Refractive cataract surgery using corneal incisions is aiming at neutralization of preoperative astigmatism. 61 patients with preoperative astigmatism of 2.25 +/- 0.98 were included in the treatment. A self-sealing corneal tunnel incision measuring 4.0 to 4.1 mm in external diameter and 6.5 to 7.0 mm in internal diameter (stretch incision) was performed on the steeper axis. After capsulorhexis and phacoemulsification a 5 mm PMMA lens was implanted without suturing. Keratometry and corneal topography were performed preoperatively, 3 days and 1 year respectively following surgery. The statistical analysis was based on the Wilcoxon signed ranks test. Surgical induced astigmatism (IA) following superior incisions in cases of astigmatism with the rule (n = 29) amounted to 1.93 +/- 0.97, while lateral incisions in cases of astigmatism against the rule (n = 29) led to an IA of 1.35 +/- 0.73. Axial shifts by more than 30 degrees were 23% following superior incisions and 17%, after lateral incisions. We observed. astigmatic reduction of 1.3 D after superior incisions and 0.7 D following lateral incisions. By 4 mm corneal cataract incisions on the steeper axis a high preoperative astigmatism can be reduced significantly without additional keratotomies.

  6. [Calculating the induced, computerized tomography measured corneal astigmatism after cataract surgery with small incision technique and wound closure with single suture technique based on various mathematical models].

    Science.gov (United States)

    Rauber, M; Grewing, R; Mester, U

    1993-08-01

    Small-incision cataract surgery with scleral tunnel incision and one-stitch horizontal or sutureless wound closure has been found to be an effective way to reduce postoperative astigmatism and to guarantee greater stability of the wound with rapid visual rehabilitation. In some studies surgically induced astigmatism by different wound constructions and wound-closure techniques has been compared to determine the astigmatism induced. Different calculation methods were used leading to different results. Therefore, we evaluated the induced astigmatism in 50 patients operated on by scleral tunnel incision, phacoemulsification with PCL implantation and single-stitch wound closure. We analyzed induced astigmatism on the first postoperative day and 3 months postoperatively by different methods: the simple subtraction method (0.91 and 0.30 D), Naeser's polar value method (-0.74 and -0.75 D), the vector analysis method of Jaffe (2.53 and 1.19 D) and two calculations described by Cravy. Depending on the formula used, different results were obtained. The subtraction method disregards axis change and is less precise. The vector analysis methods obtain the highest values for induced astigmatism and seem to be the most precise for evaluating the real amount of induced postoperative astigmatism.

  7. Two year follow-up of astigmatism after phacoemulsification with adjusted and unadjusted sutured versus sutureless 5.2 mm superior scleral incisions.

    Science.gov (United States)

    Lyhne, N; Corydon, L

    1998-12-01

    To evaluate changes in astigmatism 6 months to 2 years after 5.2 mm superior scleral incision phacoemulsification using 3 closures. Department of Ophthalmology, Vejle Hospital, Vejle, Denmark. This long-term follow-up study included 75 consecutive phacoemulsification patients who were randomly allocated to 1 of 3 incision closures: 1 intraoperatively adjusted cross suture, 1 unadjusted cross suture, no suture. Postoperative astigmatism after 1 and 2 years was evaluated by keratometric cylinder, induced astigmatism (Naeser's polar values), induced cylinder (Jaffe's vector analysis), and vector decomposition (Olsen). The data were compared with 1 week values. In the previous study, median astigmatism after 6 months was similar in all 3 groups, but only the sutureless group showed early stability. Significant against-the-rule (ATR) changes were seen in the sutured cases (P suture group exhibited stability after 6 months, while the unadjusted-suture group showed a further tendency to change ATR. At 2 years, median ranges of astigmatism were -0.49 to -0.90 diopter (D) (Naeser), 0.77 to 1.02 D (Jaffe), and 96% to 98% ATR (Olsen). The intergroup differences were not statistically significant. Two year follow-up confirmed that sutureless closure led to early astigmatism stability. Using a suture prolonged the postoperative period of astigmatism instability, and if used without intraoperative adjustment, a tendency toward a less predictable outcome persisted after 2 years.

  8. The Prevalence of Astigmatism and its Determinants in a Rural Population of Iran: The “Nooravaran Salamat” Mobile Eye Clinic Experience

    Science.gov (United States)

    Hashemi, Hassan; Rezvan, Farhad; Yekta, Abbas Ali; Hashemi, Maryam; Norouzirad, Reza; Khabazkhoob, Mehdi

    2014-01-01

    Purpose: The prevalence of astigmatism, and the astigmatic axis, and their determinants were evaluated in a rural population of Iran. Materials and Methods: In a cross-sectional study conducted from May to August 2011, 13 villages in the vicinity of the city of Khaf in northeast Iran were investigated in this study. All the examinations including visual acuity, refraction, slit-lamp biomicroscopy and fundoscopy were performed in a Mobile Eye Clinic. Written informed consent was obtained from all participants. Only phakic eye that could be reliably refracted without a previous history of ocular surgery were included. Results: Out of 2635 participants who were screened, 2124 were analysed for this study of whom 52% were female. The prevalence of astigmatism was 32.2% (95% confidence intervals (CI): 30.2-34.2). Astigmatism significantly increased from 14.3% in the under 15-year-old age group to 67.2% in the age group of over 65-years old (P prevalence of With-The-Rule (WTR), Against-The-Rule (ATR), and oblique astigmatism was 11.7%, 18.1%, and 2.4 %, respectively. ATR significantly increased with age (P prevalence. Further studies are suggested to discover the role of the environmental and genetic factors. It seems that environmental and occupational factors in the villages cause a significant increase in the prevalence of astigmatism with age. A high percentage of participants had ATR astigmatism, which was more common at older ages. PMID:24791111

  9. Visual performance in cataract patients with low levels of postoperative astigmatism: full correction versus spherical equivalent correction

    Directory of Open Access Journals (Sweden)

    Lehmann RP

    2012-03-01

    Full Text Available Robert P Lehmann1, Diane M Houtman21Lehmann Eye Center, Nacogdoches, TX, 2Alcon Research Ltd, Fort Worth, TX, USAPurpose: To evaluate whether visual performance could be improved in pseudophakic subjects by correcting low levels of postoperative astigmatism.Methods: An exploratory, noninterventional study was conducted using subjects who had been implanted with an aspheric intraocular lens and had 0.5–0.75 diopter postoperative astigmatism. Monocular visual performance using full correction was compared with visual performance using spherical equivalent correction. Testing consisted of high- and low-contrast visual acuity, contrast sensitivity, and reading acuity and speed using the Radner Reading Charts.Results: Thirty-eight of 40 subjects completed testing. Visual acuities at three contrast levels (100%, 25%, and 9% were significantly better using full correction than when using spherical equivalent correction (all P < 0.001. For contrast sensitivity testing under photopic, mesopic, and mesopic with glare conditions, only one out of twelve outcomes demonstrated a significant improvement with full correction compared with spherical equivalent correction (at six cycles per degree under mesopic without glare conditions, P = 0.046. Mean reading speed was numerically faster with full correction across all print sizes, reaching statistical significance at logarithm of the reading acuity determination (logRAD 0.2, 0.7, and 1.1 (P , 0.05. Statistically significant differences also favored full correction in logRAD score (P = 0.0376, corrected maximum reading speed (P < 0.001, and logarithm of the minimum angle of resolution/logRAD ratio (P < 0.001.Conclusions: In this study of pseudophakic subjects with low levels of postoperative astigmatism, full correction yielded significantly better reading performance and high- and low-contrast visual acuity than spherical equivalent correction, suggesting that cataractous patients may benefit from surgical

  10. Results of Intraoperative Manual Cyclotorsion Compensation for Myopic Astigmatism in Patients Undergoing Small Incision Lenticule Extraction (SMILE).

    Science.gov (United States)

    Ganesh, Sri; Brar, Sheetal; Pawar, Archana

    2017-08-01

    To study the safety, efficacy, and outcomes of manual cyclotorsion compensation in small incision lenticule extraction (SMILE) for myopic astigmatism. Eligible patients with myopia from -1.00 to -10.00 diopters (D) spherical equivalent with a minimum astigmatism of 0.75 D undergoing SMILE were included. Intraoperative cyclotorsion compensation was performed by gently rotating the cone and aligning the 0° to 180° limbal marks with the horizontal axis of the reticule of the right eye piece of the microscope of the femtosecond laser after activating the suction. In this study, 81 left eyes from 81 patients were analyzed for vector analysis of astigmatism. The mean cyclotorsion was 5.64° ± 2.55° (range: 2° to 12°). No significant differences were found for surgically induced astigmatism, difference vector, angle of error (AE), correction index, magnitude of error, index of success (IOS), and flattening index between 2 weeks and 3 months postoperatively (P > .05). The eyes were categorized into low (≤ 1.50 D, n = 37) and high (> 1.50 D, n = 44) cylinder groups. At 3 months, intergroup analysis showed a comparable correction index of 0.97 for the low and 0.93 for the high cylinder groups, suggesting a slight undercorrection of 3% and 7%, respectively (P = .14). However, the AE and IOS were significantly lower in the high compared to the low cylinder group (P = .032 and .024 for AE and IOS, respectively), suggesting better alignment of the treatment in the high cylinder group. However, the mean uncorrected distance visual acuity of both groups was comparable (P = .21), suggesting good visual outcomes in the low cylinder group despite a less favorable IOS. Manual compensation may be a safe, feasible, and effective approach to refine the results of astigmatism with SMILE, especially in higher degrees of cylinders. [J Refract Surg. 2017;33(8):506-512.]. Copyright 2017, SLACK Incorporated.

  11. Extended wavelet transformation to digital holographic reconstruction: application to the elliptical, astigmatic Gaussian beams.

    Science.gov (United States)

    Remacha, Clément; Coëtmellec, Sébastien; Brunel, Marc; Lebrun, Denis

    2013-02-01

    Wavelet analysis provides an efficient tool in numerous signal processing problems and has been implemented in optical processing techniques, such as in-line holography. This paper proposes an improvement of this tool for the case of an elliptical, astigmatic Gaussian (AEG) beam. We show that this mathematical operator allows reconstructing an image of a spherical particle without compression of the reconstructed image, which increases the accuracy of the 3D location of particles and of their size measurement. To validate the performance of this operator we have studied the diffraction pattern produced by a particle illuminated by an AEG beam. This study used mutual intensity propagation, and the particle is defined as a chirped Gaussian sum. The proposed technique was applied and the experimental results are presented.

  12. Relaxation in Thin Polymer Films Mapped across the Film Thickness by Astigmatic Single-Molecule Imaging

    KAUST Repository

    Oba, Tatsuya

    2012-06-19

    We have studied relaxation processes in thin supported films of poly(methyl acrylate) at the temperature corresponding to 13 K above the glass transition by monitoring the reorientation of single perylenediimide molecules doped into the films. The axial position of the dye molecules across the thickness of the film was determined with a resolution of 12 nm by analyzing astigmatic fluorescence images. The average relaxation times of the rotating molecules do not depend on the overall thickness of the film between 20 and 110 nm. The relaxation times also do not show any dependence on the axial position within the films for the film thickness between 70 and 110 nm. In addition to the rotating molecules we observed a fraction of spatially diffusing molecules and completely immobile molecules. These molecules indicate the presence of thin (<5 nm) high-mobility surface layer and low-mobility layer at the interface with the substrate. (Figure presented) © 2012 American Chemical Society.

  13. Slow tool servo diamond turning of optical freeform surface for astigmatic contact lens

    Science.gov (United States)

    Chen, Chun-Chieh; Cheng, Yuan-Chieh; Hsu, Wei-Yao; Chou, Hsiao-Yu; Wang, Pei-Jen; Tsai, Din Ping

    2011-09-01

    Three ultra-precision machining processes namely fast tool servo, slow tool servo and diamond milling, are frequently used to produce optical freeform surface. Slow tool servo machining has the advantages of no extra attachment and fast setting-up, however the three dimensional tool shape compensation and tool-path generation must be conducted carefully for getting high form accuracy and fine surface finish. This research aimed to develop a model of three dimensional tool shape compensation for generating 3D tool path in slow tool servo diamond turning of asymmetrically toric surface for astigmatic contact lens. The form accuracy of freeform surface was measured by ultra-high accuracy 3D profilometer (UA3P) with user define function. After correction, the form error is less than 0.5μm both in X- and Y-direction and the surface roughness is less than 5nm.

  14. Effects of astigmatic axis orientation on postural stabilization with stationary equilibrium

    Science.gov (United States)

    Kanazawa, Masatsugu; Uozato, Hiroshi; Asakawa, Ken; Kawamorita, Takushi

    2017-10-01

    We evaluated 15 healthy participants by assessing their maintenance of postural control while standing on a platform stabilometer for 1 min under the following conditions: eyes open; eyes open with + 3.00 D on both eyes on same directions (45, 90, 135, 180 degree axis); right eye on 45 degree axis and left eye on 135 degree axis (inverted V-pattern), and right eye on 135 degree axis and left eye on axis 45 degree axis (V-pattern). The differences in the linear length, area and maximum velocity of center of pressure during postural control before and after the six types of positive cylinder-oriented axes were analyzed. Comparing the antero-posterior lengths and antero-posterior maximum velocities, there were significant differences between the V-pattern condition and the six other conditions. Astigmatic defocus in the antagonistic axes conditions, particularly the V-pattern condition, affects postural control of antero-posterior sway (143/150).

  15. Measuring the 3D motion of particles in microchannel acoustophoresis using astigmatism particle tracking velocimetry

    DEFF Research Database (Denmark)

    Augustsson, P.; Barnkob, Rune; Bruus, Henrik

    2012-01-01

    We introduce full three-dimensional tracking of particles in an acoustophoresis microchannel using Astigmatism Particle Tracking Velocimetry (APTV) [1]. For the first time the interaction between acoustic streaming and the primary acoustic radiation force in microchannel acoustophoresis are exami...... relative to the influence from the acoustic radiation force. The current study opens the route to optimized acoustophoretic system design and operation to enable manipulation of small biological components such as spores, bacteria and viruses....... are examined in three dimensions. We have quantified the velocity of particles driven by the primary acoustic radiation force and acoustic streaming, respectively, using 0.5-μm and 5-μm particles. Increased ultrasound frequency and lowered viscosity of the medium reduced the influence of acoustic streaming...

  16. LASIK and PRK in hyperopic astigmatic eyes: is early retreatment advisable?

    Directory of Open Access Journals (Sweden)

    Frings A

    2016-03-01

    Full Text Available Andreas Frings,1 Gisbert Richard,1,2 Johannes Steinberg,1,3,4 Vasyl Druchkiv,1,4 Stephan Johannes Linke,1,3,4 Toam Katz1,4 1Department of Ophthalmology, University Medical Centre Hamburg-Eppendorf, 2Ophthalmologikum an der Alster, 3zentrumsehstärke, 4CARE Vision Germany GmbH, Hamburg, Germany Purpose: To analyze the refractive and keratometric stability in hyperopic astigmatic laser in situ keratomileusis (LASIK or photorefractive keratectomy (PRK during the first 6 months after surgery. Patients and methods: This retrospective cross-sectional study included 97 hyperopic eyes; 55 were treated with LASIK and 42 with PRK. Excimer ablation for all eyes was performed using the ALLEGRETTO excimer laser platform using a mitomycin C for PRK and a mechanical microkeratome for LASIK. Keratometric and refractive data were analyzed during three consecutive follow-up intervals (6 weeks, 3 months, and 6 months. The corneal topography was obtained using Scheimpflug topography, and subjective refractions were acquired by expert optometrists according to a standardized protocol. Results: After 3 months, mean keratometry and spherical equivalent were stable after LASIK, whereas PRK-treated eyes presented statistically significant (P<0.001 regression of hyperopia. In eleven cases, hyperopic regression of >1 D occurred. The optical zone diameter did not correlate with the development of regression. Conclusion: After corneal laser refractive surgery, keratometric changes are followed by refractive changes and they occur up to 6 months after LASIK and for at least 6 months after PRK, and therefore, caution should be applied when retreatment is planned during the 1st year after surgery because hyperopic refractive regression can lead to suboptimal visual outcome. Keratometric and refractive stability is earlier achieved after LASIK, and therefore, retreatment may be independent of late regression. Keywords: hyperopia, astigmatism, regression, keratometry

  17. Corneal graft curvature change after relaxing incisions for post-penetrating keratoplasty astigmatism.

    Science.gov (United States)

    Feizi, Sepehr; Javadi, Mohammad A

    2012-09-01

    To evaluate change in graft steepness after graft refractive surgery (GRS) consisting of relaxing incisions with or without counterquadrant compression sutures and discover the existing influential factors. In this retrospective study, 78 eyes of 76 patients who had received penetrating keratoplasty for keratoconus underwent GRS because of high post-penetrating keratoplasty astigmatism. Any shift in graft curvature was calculated using the keratometric coupling ratio (CR; the ratio of flattening of the incised meridian to steepening of the opposite meridian). Multiple regression analysis was used to investigate the possible effect of age, graft curvature, number of incisions, use of compression sutures, achieved vector astigmatic correction, and total arc length on CR. Mean patient age was 30.1 ± 10.3 years and mean follow-up period after GRS was 40.1 ± 29.0 months. There was a significant increase in average keratometry from 44.79 ± 2.08 diopters (D) preoperatively to 45.65 ± 1.86 D postoperatively (P < 0.001). Mean keratometric CR was 0.62 ± 1.09. Keratometric CR was significantly associated with patient age (R = 0.53, P = 0.04) and preoperative average keratometry (R = 0.61, P = 0.02). However, keratometric CR failed to show any significant correlation with other variables. A significant increase in graft steepening occurred after GRS, averaging 0.86 D. When both GRS and cataract extraction or phakic intraocular lens implantation are indicated, a staged approach (first GRS followed by phacoemulsification, for example) is advocated to calculate intraocular lens power with accuracy.

  18. [Efficiency of interlamellar refractive tunnel keratoplasty in myopia and astigmatism correction].

    Science.gov (United States)

    Shusterov, Y

    2014-10-01

    Correction of high degree myopia, anisometropia and astigmatism continues to remain one of actual problems of ophthalmology. The purpose of the present work - the analysis of results of application of refractive interlamellar tunnel keratoplasty variants. We develop 6 updatings tunnel keratoplasty. In total in clinic 310 operations from which in 158 cases as a transfer material used a donor cornea, in 63 cases - brephocornea (a fruit cornea) and in 89 cases - hydrogel synthetic implant, modified in low-temperature to gas-discharge plasma are spent. From the specified number of operative interventions, on 86 eyes of operation tunnel keratoplasty have been spent at those patients by whom earlier it has been given up in carrying out eximerlaser corrections, in connection with presence of a "thin", "flat" and "convex" cornea. Maximum refractive effect fell first two weeks after operation. Definitive stabilisation of a refraction occurred on 2-3 month, thus regress of the reached effect made an order of 10-12 %. It is reached refractive effect from 5,5 to 20,0 D. Undercorrection in some cases made to 3,5 D, that spoke very high myopia (more than 20,0 D) degrees. It has been noticed, that refractive effect of operations with ecsplants was above (on the average on 10 %), than at use of a donor cornea, at identical cross-section section of used transfer materials. It spoke that the synthetic material, unlike a donor cornea, kept the form. At all patients substantial increase of visual acuities has been received, and in 75 % it was equal or exceeded visual acuity before operation with the greatest possible correction. Thus, clinical approbation has proved, that the variants of tunnel keratoplasty, are effective ways of high myopia, anisometropia and astigmatism correction. Updating in gaseous plasma is represented in the perspective way of improvement of biocompatibility of synthetic materials.

  19. Analysis of the Ocular Refractive State in Fighting Bulls: Astigmatism Prevalence

    Directory of Open Access Journals (Sweden)

    Juan M. Bueno

    2017-01-01

    Full Text Available The purpose of this study was to describe the ocular refractive state (ORS of fighting bulls. The study consisted of 90 ophthalmological healthy animals (85 in post-mortem and 5 in living conditions, resp.. The ORS of the eyes (2 per animal was determined using streak retinoscopy. In vivo animals were assessed at a fighting bull farm facility. Post-mortem measurements were carried out at a local arena. The ORS along the horizontal meridian ranged between −1.00 and +2.50 diopters (D, with a mean of +0.66±0.85 D in post-mortem animals. Values for in vivo conditions were similar (+0.75±0.46 D. Left and right eyes were highly correlated in both sets (p<0.001. A fairly good correlation was also observed when comparing living and post-mortem eyes in the same animals. Anisometropia ≥ 1.00 D was diagnosed in 3 animals. Astigmatism (≥+0.5 D was detected in 93% of the eyes. To our knowledge, the ORS of the fighting bull has been reported for the first time. Although values vary among individuals, all eyes presented a marked astigmatism. Whereas the horizontal meridian was slightly hyperopic, the vertical meridian was always closer to emmetropia. These results represent a starting point to understand the ocular optics of this kind of animals, which might benefit the selection of animals at the farm before being sent to the bullfighting arena.

  20. Implantation of Artisan toric phakic intraocular lenses for the correction of astigmatism and spherical errors in patients with keratoconus.

    Science.gov (United States)

    Budo, Camille; Bartels, Marjolijn C; van Rij, Gabriel

    2005-01-01

    To evaluate the correction of astigmatism and spherical ametropia in patients with keratoconus through implantation of an Artisan toric phakic intraocular lens (PIOL) (Ophtec, Groningen, The Netherlands). Artisan toric PIOLs were implanted uneventfully in both eyes of three patients with keratoconus with clear central corneas and contact lens intolerance. Best spectacle-corrected subjective visual acuity after lens implantation was unchanged in one eye and improved in five eyes. Spherical equivalent refraction was significantly reduced in all eyes (P=.03). The safety index was 1.49. The implantation of an Artisan toric PIOL may be an alternative for treating astigmatism and myopia in contact lens intolerant patients with keratoconus with clear central corneas. Especially in patients with associated myopia, this procedure is worth considering before planning a penetrating keratoplasty.

  1. Topography-guided customized laser-assisted subepithelial keratectomy for the treatment of postkeratoplasty astigmatism.

    Science.gov (United States)

    Rajan, Madhavan S; O'Brart, David P S; Patel, Parul; Falcon, Mike G; Marshall, John

    2006-06-01

    To assess topography-assisted corneal wavefront excimer laser surface ablation for the correction of ametropia and irregular astigmatism after keratoplasty. Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom. In this pilot study, 15 patients (16 eyes) who were intolerant of spectacle and contact lens correction due to astigmatic anisometropia after keratoplasty (15 penetrating and 1 lamellar) had topography-assisted customized excimer laser treatments. Corneal topographic data using a Keratron Scout, Placido disk system allowed for preoperative analysis of wavefront anomalies of the anterior corneal surface from which a customized excimer laser correction of both lower-order aberrations (LOAs) and higher-order aberrations (HOAs) was prepared (ORK software) for treatment with a Schwind Esiris flying-spot laser. All eyes had laser-assisted subepithelial keratectomy (LASEK) using 15% alcohol with a 20-second to 30-second application. Four eyes received an application of mitomycin-C (MMC) 0.2 mg/mL for 1 minute after stromal ablation. The mean preoperative spherical equivalent (SE) was -3.50 diopters (D) +/- 3.97 (SD) (range +1.625 to -9.25 D). The preoperative cylindrical error was -7.2 D (range -2.75 to -13.5 D). The programmed laser correction was -3.14 D (range +1.62 to -9 D) with a maximum attempted cylindrical correction of -7 D. Adherent LASEK epithelial flaps along suture lines and the graft-host junction were noted in 9 eyes (56%), although it was possible to obtain and replace a partial flap. A follow-up of 18 months was achieved in all eyes. At the final follow-up visit, the mean postoperative SE was -1.08 +/- 1.85 D (range +3 to -4.78 D) (P<.01, F<.01). Ten eyes (62.5%) were within +/-1 D of the intended correction. The mean postoperative cylindrical error was -2.72 D (range -0.5 to -6.5 D) (P<.001), with vector analysis demonstrating a mean 6.23 D correction. Analysis of HOAs using a 6.0 mm pupil size demonstrated a significant

  2. Effect of corneal biomechanical properties on surgically-induced astigmatism and higher-order aberrations after cataract surgery

    OpenAIRE

    Mustafa Koç; Çağrı İlhan; Yaran Koban; Kemal Özülken; İrfan Durukan; Pelin Yılmazbaş

    2016-01-01

    ABSTRACT Purpose: To investigate the relationship between biomechanical properties of the cornea and postoperative refractive changes in patients with low-level astigmatism after cataract surgery. Methods: This prospective study recruited patients undergoing cataract surgery involving 2.8-mm superior incisions. Biomechanical properties of the cornea were evaluated preoperatively using the Ocular Response Analyzer, and corneal profiles were evaluated using a Scheimpflug system (Pentacam HR)....

  3. A fast Gaussian beam tracing method for reflection and refraction of general vectorial astigmatic Gaussian beams from general curved surfaces

    Science.gov (United States)

    Rohani, A.; Shishegar, A. A.; Safavi-Naeini, S.

    2004-03-01

    A fast Gaussian beam tracing method for general vectorial astigmatic Gaussian beams based on phase matching has been formulated. Given the parameters of a vectorial Gaussian beam in its principal coordinate system the parameters of the reflected and refracted beams from a general curved surface (with general constitutive parameters) are found. The reflection and transmission of such beams from and through passive photonic structures such as lenses, mirrors and prisms can then be found by considering multiple reflections and transmissions.

  4. Prevalence and associations of anisometropia and aniso-astigmatism in a population based sample of 6 year old children.

    Science.gov (United States)

    Huynh, S C; Wang, X Y; Ip, J; Robaei, D; Kifley, A; Rose, K A; Mitchell, P

    2006-05-01

    To study the distribution of anisometropia and aniso-astigmatism in young Australian children, together with clinical and ocular biometry relations. The Sydney Myopia Study examined 1765 predominantly 6 year old children from 34 randomly selected Sydney schools during 2003-4. Keratometry, cycloplegic autorefraction, and questionnaire data were collected. Spherical equivalent (SE) anisometropia (> or =1 dioptre) prevalence was 1.6% (95% confidence interval (CI) 1.1% to 2.4%). Aniso-astigmatism (>or =1D) prevalence was 1.0% (CI: 0.6% to 1.6%). Both conditions were significantly more prevalent among moderately hyperopic (SE > or =2.0D) than mildly hyperopic (SE 0.5-1.9D) children. Myopic children (SE anisometropia prevalence. Neither condition varied by age, sex, or ethnicity. In multivariate analyses, anisometropia was significantly associated with amblyopia, odds ratio (OR) 29, (CI: 8.7 to 99), exotropia (OR 7.7, CI: 1.2 to 50), and neonatal intensive care unit (NICU) admission (OR 3.6, CI: 1.1 to 12.6). Aniso-astigmatism was significantly associated with amblyopia (OR 8.2, CI: 1.4 to 47), maternal age >35 years (OR 4.0, CI: 1.3 to 11.9), and NICU admission (OR 4.6, CI: 1.2 to 17.2). Anisometropia resulted from relatively large interocular differences in axial length (panisometropia and aniso-astigmatism were uncommon, had important birth and biometry associations, and were strongly related to amblyopia and strabismus.

  5. Profile of refractive errors in European Caucasian children with Autistic Spectrum Disorder; increased prevalence and magnitude of astigmatism.

    Science.gov (United States)

    Anketell, Pamela M; Saunders, Kathryn J; Gallagher, Stephen; Bailey, Clare; Little, Julie-Anne

    2016-07-01

    Autistic Spectrum Disorder (ASD) is a common neurodevelopmental disorder characterised by impairment of communication, social interaction and repetitive behaviours. Only a small number of studies have investigated fundamental clinical measures of vision including refractive error. The aim of this study was to describe the refractive profile of a population of children with ASD compared to typically developing (TD) children. Refractive error was assessed using the Shin-Nippon NVision-K 5001 open-field autorefractor following the instillation of cyclopentolate hydrochloride 1% eye drops. A total of 128 participants with ASD (mean age 10.9 ± 3.3 years) and 206 typically developing participants (11.5 ± 3.1 years) were recruited. There was no significant difference in median refractive error, either by spherical equivalent or most ametropic meridian between the ASD and TD groups (Spherical equivalent, Mann-Whitney U307 = 1.15, p = 0.25; Most Ametropic Meridian, U305 = 0.52, p = 0.60). Median refractive astigmatism was -0.50DC (range 0.00 to -3.50DC) for the ASD group and -0.50DC (Range 0.00 to -2.25DC) for the TD group. Magnitude and prevalence of refractive astigmatism (defined as astigmatism ≥1.00DC) was significantly greater in the ASD group compared to the typically developing group (ASD 26%, TD 8%, magnitude U305 = 3.86, p = 0.0001; prevalence (χ12=17.71 , p < 0.0001). This is the first study to describe the refractive profile of a population of European Caucasian children with ASD compared to a TD population of children. Unlike other neurodevelopmental conditions, there was no increased prevalence of spherical refractive errors in ASD but astigmatic errors were significantly greater in magnitude and prevalence. This highlights the need to examine refractive errors in this population. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

  6. Comparison of grafted and non-grafted patients with corneal astigmatism undergoing cataract extraction with a toric intraocular lens implant.

    Science.gov (United States)

    Stewart, Christopher M; McAlister, James C

    2010-11-01

    Toric intraocular lenses (IOLs) are advocated as an effective treatment for both regular corneal-based astigmatism and cataract in both non-penetrating keratoplasty and penetrating keratoplasty (PK) patients. The aim of this analysis is to compare postoperative outcomes for both PK and non-PK patients to determine whether or not the past PK is relevant when calculating the appropriate IOL and predicting the postoperative results. A retrospective analysis was performed on 14 non-PK and eight PK patients who underwent cataract surgery and astigmatism correction with a Rayner toric IOL. Preoperatively, best spectacle-corrected visual acuity, biometry and refractive data were recorded. Postoperative analysis at 1 month looked at best-uncorrected visual acuity (BUVA), refractive data and IOL axis. Statistical analysis was undertaken to test for differences in outcomes between the PK and non-PK groups. Preoperatively, a significant difference was seen between cylinder and astigmatism and not between sphere, axial length or anterior chamber depth. Analysis of preoperative best spectacle-corrected visual acuity, IOL error predictability, IOL rotational stability and refractive outcomes revealed no difference between PK and non-PK groups, but a significant difference was seen postoperatively with PK patients having worse BUVA. Toric IOLs are an effective means for treating both regular corneal-based astigmatism and cataract in both PK and non-PK patient groups. Analysis of results revealed similar trends for both groups in all areas except postoperative BUVA. Further studies are planned to better understand why PK patient's BUVA did not fit the trend of the other results. © 2010 The Authors. Clinical and Experimental Ophthalmology © 2010 Royal Australian and New Zealand College of Ophthalmologists.

  7. Effect of corneal biomechanical properties on surgically-induced astigmatism and higher-order aberrations after cataract surgery

    Directory of Open Access Journals (Sweden)

    Mustafa Koç

    Full Text Available ABSTRACT Purpose: To investigate the relationship between biomechanical properties of the cornea and postoperative refractive changes in patients with low-level astigmatism after cataract surgery. Methods: This prospective study recruited patients undergoing cataract surgery involving 2.8-mm superior incisions. Biomechanical properties of the cornea were evaluated preoperatively using the Ocular Response Analyzer, and corneal profiles were evaluated using a Scheimpflug system (Pentacam HR. Topographic astigmatism, total corneal aberrations (TCA and higher-order corneal aberrations (HOCA analyses were performed preoperatively and during 1- and 3-month postoperative exams. The incidences of surgically-induced astigmatism (SIA and HOCAs were calculated using vector analyses. Associations of the preoperative biomechanical properties of the cornea with SIA and HOCAs were evaluated. Results: This study included 28 eyes of 28 patients. The preoperative corneal hysteresis (CH was 8.68 ± 1.86 mmHg, and the corneal resistance factor (CRF was 8.66 ± 1.61 mmHg. At the 1-month postoperative evaluation, significant changes were observed in HOCAs (p=0.023, TCAs (p=0.05, astigmatism (p=0.02, and trefoil (p=0.033; in contrast, differences in coma (p=0.386 and spherical aberration (SA were not significant (p=0.947. At the 3-month visit, significant changes were only observed in TCAs (p=0.02 and HOCAs (p=0.012. No relationships between the preoperative corneal hysteresis and corneal resistance factor and postoperative SIA and HOCA were identified, other than a positive correlation between the 3-month postoperative incidence of corneal hysteresis and spherical aberration. Conclusions: Despite the observed lack of relationships of preoperative biomechanical properties of the cornea with SIA and postoperative aberrations (except for SA, further studies involving larger patient groups are needed to explore the unexpected refractive deviations after cataract surgery.

  8. Effect of corneal biomechanical properties on surgically-induced astigmatism and higher-order aberrations after cataract surgery.

    Science.gov (United States)

    Koç, Mustafa; İlhan, Çağrı; Koban, Yaran; Özülken, Kemal; Durukan, İrfan; Yılmazbaş, Pelin

    2016-01-01

    To investigate the relationship between biomechanical properties of the cornea and postoperative refractive changes in patients with low-level astigmatism after cataract surgery. This prospective study recruited patients undergoing cataract surgery involving 2.8-mm superior incisions. Biomechanical properties of the cornea were evaluated preoperatively using the Ocular Response Analyzer, and corneal profiles were evaluated using a Scheimpflug system (Pentacam HR). Topographic astigmatism, total corneal aberrations (TCA) and higher-order corneal aberrations (HOCA) analyses were performed preoperatively and during 1- and 3-month postoperative exams. The incidences of surgically-induced astigmatism (SIA) and HOCAs were calculated using vector analyses. Associations of the preoperative biomechanical properties of the cornea with SIA and HOCAs were evaluated. This study included 28 eyes of 28 patients. The preoperative corneal hysteresis (CH) was 8.68 ± 1.86 mmHg, and the corneal resistance factor (CRF) was 8.66 ± 1.61 mmHg. At the 1-month postoperative evaluation, significant changes were observed in HOCAs (p=0.023), TCAs (p=0.05), astigmatism (p=0.02), and trefoil (p=0.033); in contrast, differences in coma (p=0.386) and spherical aberration (SA) were not significant (p=0.947). At the 3-month visit, significant changes were only observed in TCAs (p=0.02) and HOCAs (p=0.012). No relationships between the preoperative corneal hysteresis and corneal resistance factor and postoperative SIA and HOCA were identified, other than a positive correlation between the 3-month postoperative incidence of corneal hysteresis and spherical aberration. Despite the observed lack of relationships of preoperative biomechanical properties of the cornea with SIA and postoperative aberrations (except for SA), further studies involving larger patient groups are needed to explore the unexpected refractive deviations after cataract surgery.

  9. Association between ocular dominance and spherical/astigmatic anisometropia, age, and sex: analysis of 1274 hyperopic individuals.

    Science.gov (United States)

    Linke, Stephan J; Baviera, Julio; Richard, Gisbert; Katz, Toam

    2012-08-09

    To determine the association between ocular dominance and spherical/astigmatic anisometropia, age, and sex in hyperopic subjects. The medical records of 1274 hyperopic refractive surgery candidates were filtered. Ocular dominance was assessed with the hole-in-the-card test. Refractive error (manifest and cycloplegic) was measured in each subject and correlated to ocular dominance. Only subjects with corrected distance visual acuity of >20/22 in each eye were enrolled, to exclude amblyopia. Associations between ocular dominance and refractive state were analyzed by means of t-test, χ(2) test, Spearman correlation, and multivariate logistic regression analysis. Right and left eye ocular dominance was noted in 57.4 and 40.5% of the individuals. Nondominant eyes were more hyperopic (2.6 ± 1.27 diopters [D] vs. 2.35 ± 1.16 D; P anisometropia of >2.5 D (n = 21), the nondominant eye was more hyperopic in 95.2% (SE 4.7 ± 1.4 D) compared to 4.8% (1.8 ± 0.94 D; P anisometropia of >2.5 D (n = 27), the nondominant eye was more astigmatic in 89% (mean astigmatism -3.8 ± 1.1 D) compared to 11.1% (-1.4 ± 1.4 D; P anisometropia.

  10. Association between ocular dominance and spherical/astigmatic anisometropia, age, and sex: analysis of 10,264 myopic individuals.

    Science.gov (United States)

    Linke, Stephan J; Baviera, Julio; Munzer, Gur; Steinberg, Johannes; Richard, Gisbert; Katz, Toam

    2011-11-25

    To determine the association between ocular dominance and spherical or astigmatic anisometropia, age, and sex. Medical records of 10,264 myopic refractive surgery candidates were filtered. Ocular dominance was assessed with the hole-in-the-card test. Manifest refractive error was measured in each subject and correlated to ocular dominance. Only subjects with corrected distance visual acuity (CDVA) of >20/22 in each eye were enrolled, to exclude amblyopia. Associations between ocular dominance and refractive state were analyzed by means of the t-test, χ(2) test, Spearman correlation, and multivariate logistic regression analysis. Right and left eye ocular dominance was noted in 61.7% and 35.6% of the individuals. Ocular dominance had no significant impact on SE refraction in subjects with SE or cylindrical anisometropia anisometropia >2.5 D (n = 278) the nondominant eye was more myopic in 63.7% (SE -5.8 ± 2.64 D) compared to 36.3% (-4.69 ± 2.39 D; P anisometropia >2.5 D, nondominant eyes exhibited a higher amount of astigmatism in 75% of subjects. Nondominant eyes of subjects anisometropia >2.5 and more astigmatic for cylindrical anisometropia >0.5 D.

  11. Surgically induced astigmatism after 3.0 mm temporal and nasal clear corneal incisions in bilateral cataract surgery

    Directory of Open Access Journals (Sweden)

    Je Hwan Yoon

    2013-01-01

    Full Text Available Aims: To compare the corneal refractive changes induced after 3.0 mm temporal and nasal corneal incisions in bilateral cataract surgery. Materials and Methods: This prospective study comprised a consecutive case series of 60 eyes from 30 patients with bilateral phacoemulsification that were implanted with a 6.0 mm foldable intraocular lens through a 3.0 mm horizontal clear corneal incision (temporal in the right eyes, nasal in the left eyes. The outcome measures were surgically induced astigmatism (SIA and uncorrected visual acuity (UCVA 1 and 3 months, post-operatively. Results: At 1 month, the mean SIA was 0.81 diopter (D for the temporal incisions and 0.92 D for nasal incisions (P = 0.139. At 3 months, the mean SIA were 0.53 D for temporal incisions and 0.62 D for nasal incisions (P = 0.309. The UCVA was similar in the 2 incision groups before surgery, and at 1 and 3 months post-operatively. Conclusion: After bilateral cataract surgery using 3.0 mm temporal and nasal horizontal corneal incisions, the induced corneal astigmatic change was similar in both incision groups. Especially in Asian eyes, both temporal and nasal incisions (3.0 mm or less would be favorable for astigmatism-neutral cataract surgery.

  12. Correction ratio and vector analysis of femtosecond laser arcuate keratotomy for the correction of post-mushroom profile keratoplasty astigmatism.

    Science.gov (United States)

    Trivizki, Omer; Levinger, Eliya; Levinger, Samuel

    2015-09-01

    To evaluate the refractive and keratometric effect of arcuate keratotomy using femtosecond technology in patients with high post-keratoplasty astigmatism with a mushroom profile. Enaim Refractive Center, Tel-Aviv, Israel. Noncomparative prospective interventional case series. The arcuate depth incision was set to 80% of the minimal graft thickness, with a 60-degree angle. The mean diameter was 5.79 mm ± 0.32 (SD) according to the graft size. Patient evaluation included logMAR corrected distance visual acuity (CDVA), refraction, keratometry (K), and a complete eye examination. Twenty-seven eyes of 27 patients after keratoplasty surgery were included. Both uncorrected distance visual acuity and logMAR CDVA improved after surgery. The preoperative mean logMAR CDVA was 0.29 ± 0.37 (SD), which improved by 1 line (to 0.19 ± 0.10; P = .01). The mean refractive astigmatism was -8.43 ± 2.80 diopters (D) (range -4.5 to -15 D), and it declined at the 3-month postsurgical follow-up to -4.31 ± 0.23 D (P keratoplasty astigmatism as well as stability of the results over 1 year. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  13. Phacoemulsification and customized toric intraocular lens implantation in eyes with cataract and high astigmatism after penetrating keratoplasty.

    Science.gov (United States)

    de Sanctis, Ugo; Eandi, Chiara; Grignolo, Federico

    2011-04-01

    Phacoemulsification and implantation of a hydrophilic acrylic toric intraocular lens (IOL) (T-flex 623T) with customized cylindrical power was performed in 1 eye in 3 consecutive patients with cataract and high postkeratoplasty astigmatism (range 6.75 to 8.75 diopters [D]). Twelve months postoperatively, the uncorrected distance visual acuity improved from 20/200 to 20/30 in Case 1, from 20/400 to 20/40 in Case 2, and from 20/200 to 20/25 in Case 3 and the corrected distance visual acuity was 20/25 or better in all 3 eyes. The spheroequivalent was within ± 0.50 D of the intended value and the refractive astigmatism was less than 1.00 D. The corneal grafts were transparent, and the endothelial cell loss range was 6% to 12%. Rotation of the toric IOL was less than 5 degrees. The toric IOL with customized cylindrical power provided good postoperative rotational stability and very satisfactory postoperative visual recovery. This type of toric IOL is appropriate to correct high postkeratoplasty astigmatism in eyes operated on for cataract. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  14. LASIK and PRK in hyperopic astigmatic eyes: is early retreatment advisable?

    Science.gov (United States)

    Frings, Andreas; Richard, Gisbert; Steinberg, Johannes; Druchkiv, Vasyl; Linke, Stephan Johannes; Katz, Toam

    2016-01-01

    To analyze the refractive and keratometric stability in hyperopic astigmatic laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) during the first 6 months after surgery. This retrospective cross-sectional study included 97 hyperopic eyes; 55 were treated with LASIK and 42 with PRK. Excimer ablation for all eyes was performed using the ALLEGRETTO excimer laser platform using a mitomycin C for PRK and a mechanical microkeratome for LASIK. Keratometric and refractive data were analyzed during three consecutive follow-up intervals (6 weeks, 3 months, and 6 months). The corneal topography was obtained using Scheimpflug topography, and subjective refractions were acquired by expert optometrists according to a standardized protocol. After 3 months, mean keratometry and spherical equivalent were stable after LASIK, whereas PRK-treated eyes presented statistically significant (P1 D occurred. The optical zone diameter did not correlate with the development of regression. After corneal laser refractive surgery, keratometric changes are followed by refractive changes and they occur up to 6 months after LASIK and for at least 6 months after PRK, and therefore, caution should be applied when retreatment is planned during the 1st year after surgery because hyperopic refractive regression can lead to suboptimal visual outcome. Keratometric and refractive stability is earlier achieved after LASIK, and therefore, retreatment may be independent of late regression.

  15. [Femtosecond lenticule extraction (FLEx) - Results after 12 months in myopic astigmatism].

    Science.gov (United States)

    Blum, M; Kunert, K S; Engelbrecht, C; Dawczynski, J; Sekundo, W

    2010-12-01

    This clinical trial is focussed on the 12-month results of a new method for refractive correction, femtosecond lenticule extraction (FLEx). In a prospective 6-month study 108 eyes were treated in Erfurt and Marburg. Both a flap and a lenticule of intrastromal corneal tissue were simultaneously cut utilising the Carl Zeiss Meditec AG (Jena, Germany) VisuMax femtosecond laser system. Thereafter, the lenticule was manually removed and the flap repositioned. 31 patients all treated in Erfurt volunteered for a 12-month follow-up. UCVA and BSCVA after 12 months, objective and manifest refraction as well as slit-lamp examination and late side effects were documented. 62 eyes of 31 patients were examined in this study. The spherical equivalent before surgery was -4.81 (± 1.16) D; after 12 months -0.15 (± 0.46) D were manifest. No significant change was observed after the 6 months control. Starting with UCVA of 0.12 (± 0.09) before surgery UCVA was 1.10 (± 0.26) after 12 months. In one patient corneal ectasia was diagnosed. All other patients did not have any late side effects. The stability of the correction of myopic astigmatism with the FLEx procedure is very good. The fact that one patient presented with a corneal ectasia demonstrates that one general problem of refractive corneal surgery persists with this new fs technology. © Georg Thieme Verlag KG Stuttgart · New York.

  16. Operation of astigmatic-detection atomic force microscopy in liquid environments.

    Science.gov (United States)

    Liao, H-S; Huang, K-Y; Hwang, I-S; Chang, T-J; Hsiao, Wesley W; Lin, H-H; Hwu, E-T; Chang, C-S

    2013-10-01

    The astigmatic detection system (ADS) based on commercial optical pickup head was demonstrated to achieve a sub-nanometer sensitivity in detecting the vertical movement of an object surface in air. The detection laser spot of the ADS was sub-μm and the detection bandwidth was over 80 MHz. These advantages allow detection of high-frequency mechanical resonance of very small objects, which would have many important applications in nanotechnology. In this work, we optimized the operation conditions of ADS to achieve good sensitivity in aqueous solutions. We demonstrated good contrast and good spatial resolution of cancer cells in water with the optical profilometry mode. We also built an ADS-AFM (atomic force microscopy) for imaging in water. A novel cantilever holder was designed, and the spurious peaks were suppressed down to 26.0% of the real resonance peak. Most importantly, we demonstrated that the ADS-AFM could resolve single atomic steps on a graphite substrate and image soft DNA molecules on mica in water.

  17. Influence of corneal biomechanical properties on surgically induced astigmatism in cataract surgery.

    Science.gov (United States)

    Denoyer, Alexandre; Ricaud, Xavier; Van Went, Charles; Labbé, Antoine; Baudouin, Christophe

    2013-08-01

    To perform an overall follow-up of the morphologic, optical, and biomechanical properties of the cornea to determine new parameters influencing the refractive outcomes of cataract surgery. Clinical study. Patients scheduled for cataract surgery were assessed for surgically induced corneal astigmatism (SIA) and higher-order aberrations, (HOAs) using a Scheimpflug rotating camera (Pentacam) together with corneal imaging by optical coherence tomography (Spectralis) and biomechanical analysis by the Ocular Response Analyzer preoperatively and 1, 7, and 30 days postoperatively. The central and peripheral corneal thicknesses; incision width, length, and architecture; corneal hysteresis (CH); and corneal resistance factor (CRF) were computed to identify new parameters influencing corneal optical changes that determine the final refractive result. The study enrolled 40 patients (40 eyes). The SIA and HOAs were significantly lower after microincision surgery (≤ 2.2 mm) than after small-incision surgery (2.75 mm) (both Pcorneal incision compared with a constructed incision (PCorneal 3rd-order trefoil depended on incision width (Pbiomechanical features of the cornea should be taken into account preoperatively to better predict the refractive outcomes of cataract surgery. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  18. Comparison of surgically induced astigmatism in various incisions in manual small incision cataract surgery

    Directory of Open Access Journals (Sweden)

    Nidhi Jauhari

    2014-12-01

    Full Text Available AIM:To determine the surgically induced astigmatism (SIA in Straight, Frown and Inverted V shape (Chevron incisions in manual small incision cataract surgery (SICS.METHODS:A prospective cross sectional study was done on a total of 75 patients aged 40y and above with senile cataract. The patients were randomly divided into three groups (25 each. Each group received a particular type of incision (Straight, Frown or Inverted V shape incisions. Manual SICS with intraocular lens (IOL implantation was performed. The patients were compared 4wk post operatively for uncorrected visual acuity (UCVA, best corrected visual acuity (BCVA and SIA. All calculations were performed using the SIA calculator version 2.1, a free software program. The study was analyzed using SPSS version 15.0 statistical analysis software.RESULTS:The study found that 89.5% of patients in Straight incision group, 94.2% in Frown incision group and 95.7% in Inverted V group attained BCVA post-operatively in the range of 6/6 to 6/18. Mean SIA was minimum (-0.88±0.61D×90 degrees with Inverted V incision which was statistically significant.CONCLUSION:Inverted V (Chevron incision gives minimal SIA.

  19. Preliminary study of the association between corneal histocytological changes and surgically induced astigmatism after phacoemulsification.

    Science.gov (United States)

    Du, Xing; Zhao, Guiqiu; Wang, Qing; Yang, Xian; Gao, Ang; Lin, Jing; Wang, Qian; Xu, Qiang

    2014-11-20

    Surgically induced astigmatism (SIA) was one of the factors that influences the desirable refractive outcome, and it was related to the length, type, location, structure of the incision and to the suture closure technique, etc. The aim was to evaluate the association of corneal histocytological changes with SIA after phacoemulsification. The study enrolled 68 cases of cataract patient (68 eyes). Corneal histocytological parameters at corneal incision, central cornea and contralateral incision obtained by confocal microscope through focusing (CMTF) were compared preoperatively and 1 week, 2 weeks, 1 month, 3 months and 6 months postoperatively. These biometric parameters included the endothelial cell density, keratocyte density of posterior stromal layer, and the morphological changes. SIA was calculated by Jaffe's vector analysis. 1 From preoperatively to 1 week, 2 weeks, 1 month, 3 months and 6 months postoperatively, the endothelail cell density was decreased significantly (p incision, including the cell absent area, wave-like area, dot-like and mass-like hyperreflection, stripe-like absent area, in the endothelial layer, and the keratocyte activation, microfolds, irregular hyporeflective or hyperreflective belt, and a little dot-like hyperreflection in the posterior stroma layer. 3 The reduction of the endothelial cell density at the corneal incision at 1 week, 2 weeks, 1 month postoperatively, were positively correlated with SIA (P1 week = 0.003, P2 weeks = 0.003, P1 month = 0.032), while others were not associated with SIA statistically. The reduction of endothelail cell density and the histocytological changes at the corneal incision were associated with SIA. The underlining mechanism needs further study.

  20. Clinical utility of ocular residual astigmatism and topographic disparity vector indexes in subclinical and clinical keratoconus.

    Science.gov (United States)

    Piñero, David P; Pérez-Cambrodí, Rafael J; Soto-Negro, Roberto; Ruiz-Fortes, Pedro; Artola, Alberto

    2015-12-01

    We aimed to characterize the distribution of the vector parameters ocular residual astigmatism (ORA) and topography disparity (TD) in a sample of clinical and subclinical keratoconus eyes, and to evaluate their diagnostic value to discriminate between these conditions and healthy corneas. This study comprised a total of 43 keratoconic eyes (27 patients, 17-73 years) (keratoconus group), 11 subclinical keratoconus eyes (eight patients, 11-54 years) (subclinical keratoconus group) and 101 healthy eyes (101 patients, 15-64 years) (control group). In all cases, a complete corneal analysis was performed using a Scheimpflug photography-based topography system. Anterior corneal topographic data was imported from it to the iASSORT software (ASSORT Pty. Ltd), which allowed the calculation of ORA and TD. Mean magnitude of the ORA was 3.23 ± 2.38, 1.16 ± 0.50 and 0.79 ± 0.43 D in the keratoconus, subclinical keratoconus and control groups, respectively (p keratoconus, subclinical keratoconus and control groups, respectively (p keratoconus. The diagnostic ability of these parameters for the detection of subclinical keratoconus was more limited (ORA: cutoff 1.17 D, sensitivity 60.0 %, specificity 84.2 %; TD: cutoff 1.29 D, sensitivity 80.0 %, specificity 80.2 %). The vector parameters ORA and TD are able to discriminate with good levels of precision between keratoconus and healthy corneas. For the detection of subclinical keratoconus, only TD seems to be valid.

  1. Correction of hyperopia with astigmatism following radial keratotomy with daily disposable plus spherical contact lens: a case report.

    Science.gov (United States)

    Chen, Yun-Wen; Lee, Jiahn-Shing; Hou, Chiun-Ho; Lin, Ken-Kuo

    2017-08-30

    To report the refractive correction in a case of hyperopia and astigmatism following radial keratotomy. A case report. A 47-year-old woman, who had undergone refractive surgery for radial keratotomy in both eyes 22 years before the present study, presented to our clinic with blurred vision. Her best corrected visual acuity, with spectacle correction of +3.50 DS/-1.50 DCX130° in the right eye and +3.75 DS/-1.50 DCX80° in the left eye, was 0.2 logMAR and 0.3 logMAR, respectively. Her keratometric readings were 35.75 D/36.75 D at 74° and 35.25 D/36.25 D at 61°, respectively. Prompted by intolerance to glasses, the patient requested for contact lenses. First, we applied a rigid, gas-permeable contact lens. However, we noted poor fitting due to central corneal flattening. Subsequently, we applied a conventional plus spherical soft contact lens (PSSCL), which is thick in the center and can therefore correct hyperopia and low-grade astigmatism simultaneously. The conventional PSSCL showed slightly inferior decentration, with good movement, and the patient was satisfied with it. After ascertaining the patient's living habits, we decided that a daily disposable soft contact lens would most meet her needs. The final prescription was a daily disposable PSSCL; the patient was satisfied with her corrected visual acuity of 0.0 logMAR in the right eye and 0.0 logMAR in left eye. Her daily disposable PSSCL-corrected visual acuity was stable during the 10-month follow-up. For patients displaying hyperopia with astigmatism following radial keratotomy, the PSSCL may confer better corrected visual acuity and acceptability.

  2. [Vector analysis of surgically induced astigmatism after combined operation of phacoemulsification, intraocular lens implantation and pars plana vitrectomy].

    Science.gov (United States)

    Cisiecki, Sławomir; Nawrocki, Jerzy

    2005-01-01

    To evaluate the changes in corneal shape after phacoemulsification, PC IOL implantation and pars plana vitrectomy. This study comprised 25 eyes of 25 patients who received phacoemulsification, 5.5 mm PMMA IOL implantation through 6 mm clear cornea incision with one single suture, and pars plana vitrectomy in one step - group A. To unique and compare the differences in surgical induced astigmatism (SIA) between combined procedures and two steps procedures, 2 control groups in one step surgery (only phacoemulsification with PCIOL--group B or only pars plana vitrectomy--group C) with the same shape and location of incision in cataract surgery and sclerotomy sites were analyzed. The highest value of SIA was in group A which was not statistic significant different than group B (p = 0.97). In-group C, SIA was the lowest, and there was also not significant difference between groups A (p = 0.063). The differences in SIA between group B and C were statistic irrelevant too. (P = 0.09) Shifts in axis to with the rule component were noted in 43.9 % of cases in-group A, 40.79% in-group B, and 58.96% in-group C. The highest shift in axis to against the rule meridian was observed in-group B (tab. 2) and in direction with the rule in-group C. No statistical significance was observed in the amounts of the induced astigmatism and refractive cylinder among the group of combined phacoemulsification, IOL implantation and pars plana vitrectomy. However, optical rehabilitation can be delayed by a postoperative astigmatism.

  3. Artisan iris-fixated toric phakic intraocular lens for the correction of high astigmatism after deep anterior lamellar keratoplasty.

    Science.gov (United States)

    Al-Dreihi, Madonna G; Louka, Bachar I; Anbari, Anas A

    2013-01-01

    We report the refractive correction of high astigmatism in one eye of a 23-year-old woman following deep anterior lamellar keratoplasty (DALK) using an Artisan iris-fixated, toric, phakic intraocular lens (IOL). One year after implantation, uncorrected and corrected distance visual acuities were both 20/25, refraction was -1.00 D cylinder, and the endothelial cell count was 1827 cells/mm(2). Iris-fixated phakic IOLs are not recommended for every postkeratoplasty patient with high refractive error; however, this procedure can offer good outcomes in carefully selected cases of previous DALK.

  4. Implantation of a Multifocal Toric Intraocular Lens after Radial Keratotomy and Cross-Linking with Hyperopia and Astigmatism Residues: A Case Report.

    Science.gov (United States)

    Nuzzi, Raffaele; Monteu, Francesca; Tridico, Federico

    2017-01-01

    Radial keratotomy is a refractive surgical technique, widely used in the 80s and early 90s to correct myopia and astigmatism, but now overcome by more recent laser techniques. Important consequences, often in patients with more than 45 years of age, are progressive hyperopic shift and/or an increase in corneal astigmatism, whose main cause seems to be an increase in the curvature radius of the central portion of the cornea. This seems to be due to radial keratotomy incisions - with the consequent need for cross-linking - intraocular pressure, and corneal biomechanical parameters. The authors propose phacoemulsification with a customized multifocal toric intraocular lens implantation to correct the induced shift and hyperopic astigmatism. A decent postoperative visual acuity was observed with good patient satisfaction. A specific protocol must be applied to optimize the correct diagnosis, presurgical evaluation and postsurgical outcomes that are to be maintained over time, without regressions.

  5. Implantation of a Multifocal Toric Intraocular Lens after Radial Keratotomy and Cross-Linking with Hyperopia and Astigmatism Residues: A Case Report

    Directory of Open Access Journals (Sweden)

    Raffaele Nuzzi

    2017-08-01

    Full Text Available Radial keratotomy is a refractive surgical technique, widely used in the 80s and early 90s to correct myopia and astigmatism, but now overcome by more recent laser techniques. Important consequences, often in patients with more than 45 years of age, are progressive hyperopic shift and/or an increase in corneal astigmatism, whose main cause seems to be an increase in the curvature radius of the central portion of the cornea. This seems to be due to radial keratotomy incisions – with the consequent need for cross-linking – intraocular pressure, and corneal biomechanical parameters. The authors propose phacoemulsification with a customized multifocal toric intraocular lens implantation to correct the induced shift and hyperopic astigmatism. A decent postoperative visual acuity was observed with good patient satisfaction. A specific protocol must be applied to optimize the correct diagnosis, presurgical evaluation and postsurgical outcomes that are to be maintained over time, without regressions.

  6. Correlation between the graft–host junction of penetrating keratoplasty by anterior segment-optical coherence tomography and the magnitude of postoperative astigmatism

    Directory of Open Access Journals (Sweden)

    Ghada Azab Nassar

    2017-01-01

    Full Text Available Purpose: This study aimed to evaluate the alignment pattern of the graft–host junction after penetrating keratoplasty (PK by anterior segment-optical coherence tomography (AS-OCT and to correlate this pattern with the magnitude of postoperative astigmatism. Methods: This retrospective observational study was carried out on forty patients who underwent PK from February 2013 to August 2014. AS-OCT was performed, and the graft–host junctions were classified into well-apposed junction, malapposed junction, and equally apposed junction. Mal-apposition is subdivided into gap and protrusion. The correlations between clinical characteristics, wound profiles from the AS-OCT, and the magnitude of postoperative astigmatism by Sirius camera (Costruzione Strumenti Oftalmici [CSO], Florence, Italy (CSO, Sirius, were analyzed. Results: Graft–host junctions from forty patients were analyzed; 18 eyes had well-apposed junctions, ten eyes had malapposed junctions, and 12 had equally apposed junctions. The mean cylinder was −9.44 ± −4.00D in well-apposed group, −13.40 ± −5.01D in malapposed group, and −4.67 ± −0.94D in equally apposed group. Alignment pattern of the graft–host junction correlated significantly with the magnitude of astigmatism (P = 0.034. Preoperative corneal diseases did not have an effect on the magnitude of astigmatism (P = 0.123. Conclusion: The alignment pattern of the graft–host junction by AS-OCT can explain the postoperative astigmatism after PK where it correlates significantly with the magnitude of astigmatism.

  7. Implantation of a Multifocal Toric Intraocular Lens after Radial Keratotomy and Cross-Linking with Hyperopia and Astigmatism Residues: A Case Report

    OpenAIRE

    Raffaele Nuzzi; Francesca Monteu; Federico Tridico

    2017-01-01

    Radial keratotomy is a refractive surgical technique, widely used in the 80s and early 90s to correct myopia and astigmatism, but now overcome by more recent laser techniques. Important consequences, often in patients with more than 45 years of age, are progressive hyperopic shift and/or an increase in corneal astigmatism, whose main cause seems to be an increase in the curvature radius of the central portion of the cornea. This seems to be due to radial keratotomy incisions – with the conseq...

  8. Laser-assisted in situ keratomileusis for correction of astigmatism and increasing contact lens tolerance after penetrating keratoplasty.

    Science.gov (United States)

    Park, Chang-Hyun; Kim, Su-Young; Kim, Man-Soo

    2014-10-01

    To determine effectiveness of laser-assisted in situ keratomileusis (LASIK) in the treatment of astigmatism following penetrating keratoplasty (PK). We performed a retrospective review of medical records of patients who underwent LASIK following PK and had over 1 year of follow-up data. Twenty-six patients (26 pairs of eyes) underwent LASIK following PK. Mean age of the patients at the time of LASIK was 40.7 years (range, 26 to 72 years). Following LASIK, the mean cylinder was reduced by 2.4 diopters and mean reduction of cylinder after LASIK was 65.4% from the preoperative values at the last follow-up visit. Uncorrected visual acuity became 20 / 50 or better in 69.2% of the eyes after LASIK. Best-corrected visual acuity became 20 / 50 or better in 73.1% of the eyes after LASIK. All of them were intolerable to contact lenses before LASIK. After LASIK, 6 pairs (23.1%) did not need to use contact lenses and 18 pairs (69.2%) were tolerable to using contact lenses or spectacles. There were no significant endothelial cell density changes 12 months after LASIK (p = 0.239). LASIK is effective in the treatment of astigmatism following PK and increases contact lens and spectacle tolerance.

  9. Refractive lenticule extraction (ReLEx through a small incision (SMILE for correction of myopia and myopic astigmatism: current perspectives

    Directory of Open Access Journals (Sweden)

    Ağca A

    2016-10-01

    Full Text Available Alper Ağca,1 Ahmet Demirok,2 Yusuf Yıldırım,1 Ali Demircan,1 Dilek Yaşa,1 Ceren Yeşilkaya,1 İrfan Perente,1 Muhittin Taşkapılı1 1Beyoğlu Eye Research and Training Hospital, 2Department of Ophthalmology, Istanbul Medeniyet University, Istanbul, Turkey Abstract: Small-incision lenticule extraction (SMILE is an alternative to laser-assisted in situ keratomileusis (LASIK and photorefractive keratectomy (PRK for the correction of myopia and myopic astigmatism. SMILE can be performed for the treatment of myopia ≤-12 D and astigmatism ≤5 D. The technology is currently only available in the VisuMax femtosecond laser platform. It offers several advantages over LASIK and PRK; however, hyperopia treatment, topography-guided treatment, and cyclotorsion control are not available in the current platform. The working principles, potential advantages, and disadvantages are discussed in this review. Keywords: SMILE, small-incision lenticule extraction, femtosecond laser, laser in situ keratomileusis, corneal biomechanics

  10. Genome-wide association study for refractive astigmatism reveals genetic co-determination with spherical equivalent refractive error: the CREAM consortium

    NARCIS (Netherlands)

    Q. Li (Qing); R. Wojciechowski (Robert); C.L. Simpson (Claire); P.G. Hysi (Pirro); V.J.M. Verhoeven (Virginie); M.K. Ikram (Kamran); R. Höhn (René); V. Vitart (Veronique); A.W. Hewit (Alex); K. Oexle (Konrad); K.M. Makela (Kari Matti); S. MacGregor (Stuart); M. Pirastu (Mario); Q. Fan (Qiao); C-Y. Cheng (Ching-Yu); B. St Pourcain (Beate); G. Mcmahon (George); J.P. Kemp (John); K. Northstone (Kate); J.S. Rahi (Jugnoo); P. Cumberland (Phillippa); N.G. Martin (Nicholas); P.G. Sanfilippo (Paul G.); Y. Lu (Yi); Y. Wang (Ying); C. Hayward (Caroline); O. Polasek (Ozren); H. Campbell (Harry); G. Bencic (Goran); A. Wright (Alan); J. Wedenoja (Juho); T. Zeller (Tanja); A. Schillert (Arne); A. Mirshahi (Alireza); K.J. Lackner (Karl); S.P. Yip (Shea Ping); M.K.H. Yap (Maurice K. H.); J.S. Ried (Janina); C. Gieger (Christian); D. Murgia (Daniela); J.F. Wilson (James F); B.W. Fleck (Brian W.); S. Yazar (Seyhan); J.R. Vingerling (Hans); A. Hofman (Albert); A.G. Uitterlinden (André); F. Rivadeneira Ramirez (Fernando); N. Amin (Najaf); L.C. Karssen (Lennart); B.A. Oostra (Ben); X. Zhou (Xin); Y.Y. Teo (Yik Ying); E.S. Tai (Shyong); E.N. Vithana (Eranga); V.A. Barathi (Veluchamy); Y. Zheng (Yingfeng); R. Siantar (Rosalynn); K. Neelam (Kumari); Y. Shin (Youchan); J. Lam (Janice); E. Yonova-Doing (Ekaterina); C. Venturini (Cristina); S.M. Hosseini (S Mohsen); H.-S. Wong (Hoi-Suen); T. Lehtimäki (Terho); M. Kähönen (Mika); O. Raitakari (Olli); N.J. Timpson (Nicholas); D.M. Evans (David M.); C.C. Khor; T. Aung (Tin); T.L. Young (Terri); P. Mitchell (Paul); B.E.K. Klein (Barbara); C.M. van Duijn (Cornelia); T. Meitinger (Thomas); J.B. Jonas (Jost B.); P.N. Baird (Paul); D.A. Mackey (David); T.Y. Wong (Tien Yin); S-M. Saw (Seang-Mei); O. Pärssinen (Olavi); D.E. Stambolian (Dwight); C.J. Hammond (Christopher); C.C.W. Klaver (Caroline); C. Williams (Cathy); A.D. Paterson (Andrew); J.E. Bailey-Wilson (Joan E.); J. Guggenheim (Jean)

    2015-01-01

    textabstractTo identify genetic variants associated with refractive astigmatism in the general population, meta-analyses of genome-wide association studies were performed for: White Europeans aged at least 25 years (20 cohorts, N = 31,968); Asian subjects aged at least 25 years (7 cohorts,

  11. [Limbus-parallel keratotomies with compression sutures in treatment of high astigmatism after perforating keratoplasty: a vector analysis and topographic study].

    Science.gov (United States)

    Vilchis, E; Seitz, B; Langenbucher, A; Küchle, M; Kus, M M; Naumann, G O

    1997-09-01

    Visual acuity following penetrating keratoplasty is frequently limited by excessive astigmatism which cannot be compensated for with spectacles or contact lenses. The purpose of the study was to determine the effects of arcuate keratotomies and compression sutures on the amount and regularity of corneal astigmatism and on the visual acuity. Between June 1989 and August 1995, 56 eyes from 56 patients (30 women, 26 men, average age 53 +/- 16 years) with excessive post-penetrating keratoplasty astigmatism were treated with paired arcuate cuts and compression sutures 4.8 +/- 3.5 years after suture removal (45% keratoconus, 30% scars, 20% dystrophies). The incisions were made along the meridian of maximum dioptric power in a sector extending for 60 +/- 15 degrees (6 mm diameter). Incision depth was standardized at 450 microns. Compression sutures were placed 90 degrees away in the flat meridian. Eight patients required more than one procedure to obtain the desired effect. Best corrected visual acuity (VA), keratometric readings and topographic power maps were analyzed pre- and postoperatively. We categorized the topographic maps into six groups: from group 1 (regular) to group 6 (irregular). For description of the astigmatic change after surgery, the formulas by Naylor and Jaffe (vector-corrected astigmatism) were applied. The mean preoperative astigmatism was 10.8 +/- 3.1 (4.2 to 19.2) diopters (D). After a mean follow-up of 1.1 years, the mean net astigmatism was 5.8 +/- 3.2 (0 to 16) D. The mean preoperative visual acuity (VA) was 0.38 +/- 0.31 (from 0.03 to 1.0). At the end of follow-up, the mean VA was 0.43 +/- 0.25. Non-refractive reasons for poor visual acuity included amblyopia (n = 5), macular degeneration (n = 4), glaucoma (n = 4), cataract (n = 2), and others (n = 5). Twenty-seven percent of the preoperative topographic maps were categorized into groups 1 and 2 and only 10% into groups 5 and 6. At the end of the follow-up, none of the 53 available topographic

  12. Generating high-peak-power structured lights in selectively pumped passively Q-switched lasers with astigmatic mode transformations

    Science.gov (United States)

    Chang, C. C.; Hsieh, Y. H.; Lee, C. Y.; Sung, C. L.; Tuan, P. H.; Tung, J. C.; Liang, H. C.; Chen, Y. F.

    2017-12-01

    Various high-order Hermite–Gaussian (HG) modes with high repetition rates and high peak powers are systematically generated by designing the cavity configuration to satisfy the criterion of the passive Q-switching. For the HG m,0 modes with the order m  =  1–9, the pulse repetition rate can exceed 100 kHz with peak power higher than 0.3 kW. For the HG m,m modes with the order m  =  1–10, the pulse repetition rate can be up to 37 kHz with peak power higher than 0.35 kW. Furthermore, the high-order HG beams is transformed by using an astigmatic mode converter to generate various structured lights with optical vortices. Experimental patterns of the transformed high-order HG beams in the propagation are theoretically analyzed and the phase structures are numerically manifested.

  13. Associations between anisometropia, amblyopia, and reduced stereoacuity in a school-aged population with a high prevalence of astigmatism.

    Science.gov (United States)

    Dobson, Velma; Miller, Joseph M; Clifford-Donaldson, Candice E; Harvey, Erin M

    2008-10-01

    To describe the relation between magnitude of anisometropia and interocular acuity difference (IAD), stereoacuity (SA), and the presence of amblyopia in school-aged members of a Native American tribe with a high prevalence of astigmatism. Refractive error (cycloplegic autorefraction confirmed by retinoscopy), best corrected monocular visual acuity (VA; Early Treatment Diabetic Retinopathy Study logMAR charts), and best corrected SA (Randot Preschool Stereoacuity Test) were measured in 4- to 13-year-old Tohono O'odham children (N = 972). Anisometropia was calculated in clinical notation (spherical equivalent and cylinder) and in two forms of vector notation that take into account interocular differences in both axis and cylinder magnitude. Astigmatism >or= 1.00 D was present in one or both eyes of 415 children (42.7%). Significant increases in IAD and presence of amblyopia (IAD >or= 2 logMAR lines) occurred, with >or=1 D of hyperopic anisometropia and >or=2 to 3 D of cylinder anisometropia. Significant decreases in SA occurred with >or=0.5 D of hyperopic, myopic, or cylinder anisometropia. Results for vector notation depended on the analysis used, but also showed disruption of SA at lower values of anisometropia than were associated with increases in IAD and presence of amblyopia. Best corrected IAD and presence of amblyopia are related to amount and type of refractive error difference (hyperopic, myopic, or cylindrical) between eyes. Disruption of best corrected random dot SA occurs with smaller interocular differences than those producing an increase in IAD, suggesting that the development of SA is particularly dependent on similarity of the refractive error between eyes.

  14. Aspheric Micro-monovision LASIK in Correction of Presbyopia and Myopic Astigmatism: Early Clinical Outcomes in a Chinese Population.

    Science.gov (United States)

    Zhang, Ting; Sun, Yuan; Weng, Shengbei; Liu, Manli; Zhou, Yugui; Yang, Xiaonan; Stojanovic, Aleksandar; Liu, Quan

    2016-10-01

    To analyze early clinical outcomes of aspheric micro-monovision LASIK for correction of presbyopia and myopia with or without astigmatism. Prospective, non-comparative case series of 80 eyes of 40 patients with a mean age of 43.4 ± 4.9 years (range: 38 to 63 years) treated bilaterally using an aspheric micro-monovision protocol. The target refraction was plano for the distance eye and between -0.75 and -2.25 diopters (D) for the near eye. Visual acuity, ocular aberrations, contrast sensitivity, corneal topography, amplitude of accommodation, binocular sensorial function, and satisfaction score questionnaires were evaluated at 3 months after surgery. Three months after surgery, the mean spherical equivalent (SE) refraction in the distance eye was -0.08 ± 0.27 D, whereas the attempted and achieved SE in the near eye were -1.41 ± 0.28 and -1.32 ± 0.35 D, respectively. Ninety-three percent of eyes were within ±0.50 D of target correction of SE. The uncorrected distance visual acuity (UDVA) after surgery was -0.10 ± 0.06 logMAR (20/15.5), 0.22 ± 0.12 logMAR (20/34), and -0.11 ± 0.06 logMAR (20/15), for distance eyes, near eyes, and binocularly, respectively. Ninety-five percent of patients achieved simultaneously uncorrected distance visual acuity 0.0 logMAR (20/20) or better and uncorrected near visual acuity J2 (20/25) or better. Stability was achieved from 1 week of follow-up. The overall satisfaction score for surgery was 92 ± 6. The aspheric micro-monovision protocol provided a well-tolerated and effective means for treating myopic astigmatism and alleviating presbyopic symptoms simultaneously. [J Refract Surg. 2016;32(10):680-685.]. Copyright 2016, SLACK Incorporated.

  15. Evaluation of the diagnostic ability of vector parameters characterizing the corneal astigmatism and regularity in clinical and subclinical keratoconus.

    Science.gov (United States)

    Martínez-Abad, Antonio; Piñero, David P; Ruiz-Fortes, Pedro; Artola, Alberto

    2017-04-01

    To evaluate the diagnostic ability of the vector parameters ocular residual astigmatism (ORA), topography disparity (TD) and topographic astigmatism CorT (anterior and total) for the detection of clinical and subclinical keratoconus, and to develop a detection model based on them. This study comprised a total of 61 keratoconus eyes (KC group), 19 eyes with subclinical keratoconus (SKC group) and 100 healthy eyes (control group). In all cases, a complete eye exam was performed including an analysis of the corneal structure with the Sirius system (Costruzione Strumenti Oftalmici, CSO). Likewise, the iASSORT software (ASSORT Pty) was used to calculate in all cases the vector parameters ORA, TD and CorT. Significant differences among groups were found in ORA, TD and CorT (anterior and total) (pkeratoconus was good, whereas anterior and total CorT showed a poorer diagnostic ability. ORA (cutoff 0.925 D, sensitivity/specificity 63.2%/77%) and TD (cutoff 0.710 D, sensitivity/specificity 74%/68%) showed an acceptable diagnostic ability for the detection of subclinical keratoconus, but anterior and total CorT did not. A detection model for subclinical keratoconus was obtained by logistic regression analysis involving TD, anterior corneal spherical aberration and posterior high order aberrations. The vector parameters ORA and TD are useful for the diagnosis of clinical and subclinical keratoconus. In this last condition, the combination of TD with corneal aberrometric data provides a consistent detection model. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  16. Flap-induced astigmatism in eyes with sphere myopia correction: Superior hinge using a rotating microkeratome versus nasal hinge using a linear microkeratome.

    Science.gov (United States)

    Katz, Toam; Frings, Andreas; Richard, Gisbert; Steinberg, Johannes; Druchkiv, Vasyl; Linke, Stephan J

    2015-06-01

    To compare the effect of a rotating microkeratome (M2) and a linear microkeratome (SBK) on the change in the astigmatic component in eyes with preoperative plano refractive cylinder. University Medical Centre Hamburg-Eppendorf, Hamburg, Germany. Retrospective case series. An Allegretto excimer laser was used to perform laser ablation in myopic eyes of consecutive patients. The laser in situ keratomileusis (LASIK) procedure included mechanical flap preparation using a microkeratome, either a linear type with a single-use 90 μm head to create a nasal hinge or a rotating type with a single-use 90 μm head to create a superior hinge. The Alpins vector method was applied to describe the effects of LASIK on postoperative refractive cylinder. The study evaluated 1045 eyes of 852 patients. Although the mean overall efficacy and safety indices indicate the procedure was highly precise, safe, and efficient, there were statistically significant differences in surgically induced astigmatism (SIA) between the microkeratomes (P = .002). The postoperative refractive cylinder (ie, SIA) was 0.75 diopter (D) or more in 116 eyes (11.1%), 44 (12.8%) of 344 linear cases and 72 (10.3%) of 701 rotating cases. Independent of the type of microkeratome used, the SIA was slightly higher in eyes treated first; the mean magnitude of the induced astigmatism was 0.35 D. In approximately 10% of eyes with preoperative plano refractive myopia, the astigmatic component tended to be overcorrected. Nevertheless, independent of the type of microkeratome, the maximum mean magnitude of refractive cylinder documented was 0.35 D. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  17. Comparison of surgically induced astigmatism between horizontal and X-pattern sutures in the scleral tunnel incisions for manual small incision cataract surgery.

    Science.gov (United States)

    Eslami, Yadollah; Mirmohammadsadeghi, Arash

    2015-07-01

    Two types of popular scleral tunnel sutures in the manual small incision cataract surgery (MSICS) are horizontal and X-pattern sutures. Surgically induced corneal astigmatism (SIA) is a useful indicator of the suturing effect. To compare SIA between horizontal and X-pattern sutures in the scleral tunnel incisions for MSICS. Prospective, nonrandomized comparative trial. After superior scleral tunnel incision and capsulorhexis, the nucleus was prolapsed into the anterior chamber and delivered. The wound was sutured with either horizontal or X-pattern suture. The simulated keratometry values were derived from the corneal topography preoperatively and 1.5 and 3 months postoperatively. The SIA was calculated by Cartesian coordinates based analysis. Sixty-four patients (32 patients in each group) were included in the study. In the horizontal suture group, the SIA centroid values at 1.5 and 3 months after the surgery were 0.87 × 1° and 1.11 × 180°, respectively, showing induction of against-the-rule astigmatism. In the X-pattern suture group, the SIA centroid values at 1.5 and 3 months after the surgery were 0.61 × 97° and 0.66 × 92°, respectively, showing induction of mild with-the-rule astigmatism. The difference between the amount of SIA at 1.5 and 3 months after surgery was small. In the MSICS, the X-pattern sutures were preferred to the horizontal sutures in the patients without significant preoperative steepening in line with the central meridian of the incision. In the cases with significant preoperative steepening, sutureless surgery or horizontal sutures were preferred. Corneal astigmatism in the patients undergoing MSICS was stable at 1.5 months after the surgery.

  18. Comparison of surgically induced astigmatism between horizontal and X-pattern sutures in the scleral tunnel incisions for manual small incision cataract surgery

    Directory of Open Access Journals (Sweden)

    Yadollah Eslami

    2015-01-01

    Full Text Available Background: Two types of popular scleral tunnel sutures in the manual small incision cataract surgery (MSICS are horizontal and X-pattern sutures. Surgically induced corneal astigmatism (SIA is a useful indicator of the suturing effect. Aims: To compare SIA between horizontal and X-pattern sutures in the scleral tunnel incisions for MSICS. Design: Prospective, nonrandomized comparative trial. Materials and Methods: After superior scleral tunnel incision and capsulorhexis, the nucleus was prolapsed into the anterior chamber and delivered. The wound was sutured with either horizontal or X-pattern suture. The simulated keratometry values were derived from the corneal topography preoperatively and 1.5 and 3 months postoperatively. Statistical Analysis: The SIA was calculated by Cartesian coordinates based analysis. Results: Sixty-four patients (32 patients in each group were included in the study. In the horizontal suture group, the SIA centroid values at 1.5 and 3 months after the surgery were 0.87 × 1° and 1.11 × 180°, respectively, showing induction of against-the-rule astigmatism. In the X-pattern suture group, the SIA centroid values at 1.5 and 3 months after the surgery were 0.61 × 97° and 0.66 × 92°, respectively, showing induction of mild with-the-rule astigmatism. The difference between the amount of SIA at 1.5 and 3 months after surgery was small. Conclusion: In the MSICS, the X-pattern sutures were preferred to the horizontal sutures in the patients without significant preoperative steepening in line with the central meridian of the incision. In the cases with significant preoperative steepening, sutureless surgery or horizontal sutures were preferred. Corneal astigmatism in the patients undergoing MSICS was stable at 1.5 months after the surgery.

  19. Autorefraction, Retinoscopy, Javal’s Rule, and Grosvenor’s Modified Javal’s Rule: The Best Predictor of Refractive Astigmatism

    Directory of Open Access Journals (Sweden)

    Kofi Asiedu

    2016-01-01

    Full Text Available The aim of the study was to determine the level of agreement between Javal’s rule, autorefraction, retinoscopy, and refractive astigmatism and to determine which technique is the most suitable substitute when subjective refraction is not applicable using a clinical sample. A total of 36 subjects, 14 males and 22 females, were involved in this study. The intraclass correlation coefficients between subjective refraction, autorefraction, and retinoscopy were 0.895 and 0.989, respectively, for the spherical equivalent. The Bland-Altman 95% limits of agreement between subjective refraction and autorefraction; subjective refraction and retinoscopy; and autorefraction and retinoscopy were −2.84 to 3.58, −0.88 to 1.12, and −3.01 to 3.53, respectively, for the spherical equivalent. The intraclass correlation coefficients between spectacle total astigmatism and the following techniques were as follows: retinoscopy (0.85; autorefraction (0.92; Javal’s rule (0.82; and Grosvenor et al. version (0.85. The Bland-Altman 95% limits of agreement between subjective refraction and autorefraction; subjective refraction and retinoscopy; subjective refraction and Javal’s rule; and subjective refraction and Grosvenor et al. version were −0.87 to 1.25, −1.49 to 1.99, −0.73 to 1.93, and −0.89 to 1.7, respectively, for the total astigmatism. The study showed that autorefraction and Javal’s rule may provide a starting point for subjective refraction cylinder power determination but only retinoscopy may satisfactorily replace subjective refraction total astigmatism when subjective refraction is not applicable.

  20. Successful toric intraocular lens implantation in a patient with induced cataract and astigmatism after posterior chamber toric phakic intraocular lens implantation: a case report

    Directory of Open Access Journals (Sweden)

    Kamiya Kazutaka

    2012-04-01

    Full Text Available Abstract Introduction We report the case of a patient in whom simultaneous toric phakic intraocular lens removal and phacoemulsification with toric intraocular lens implantation were beneficial for reducing pre-existing astigmatism and acquiring good visual outcomes in eyes with implantable collamer lens-induced cataract and astigmatism. Case presentation A 53-year-old woman had undergone toric implantable collamer lens implantation three years earlier. After informed consent was obtained, we performed simultaneous toric implantable collamer lens removal and phacoemulsification with toric intraocular lens implantation. Preoperatively, the manifest refraction was 0, -0.5 × 15, with an uncorrected visual acuity of 0.7 and a best spectacle-corrected visual acuity of 0.8. Postoperatively, the manifest refraction was improved to 0, -0.5 × 180, with an uncorrected visual acuity of 1.2 and a best spectacle-corrected visual acuity of 1.5. No vision-threatening complications were observed. Conclusion Toric intraocular lens implantation may be a good surgical option for the correction of spherical and cylindrical errors in eyes with implantable collamer lens-induced cataract and astigmatism.

  1. Anti-drift and auto-alignment mechanism for an astigmatic atomic force microscope system based on a digital versatile disk optical head.

    Science.gov (United States)

    Hwu, E-T; Illers, H; Wang, W-M; Hwang, I-S; Jusko, L; Danzebrink, H-U

    2012-01-01

    In this work, an anti-drift and auto-alignment mechanism is applied to an astigmatic detection system (ADS)-based atomic force microscope (AFM) for drift compensation and cantilever alignment. The optical path of the ADS adopts a commercial digital versatile disc (DVD) optical head using the astigmatic focus error signal. The ADS-based astigmatic AFM is lightweight, compact size, low priced, and easy to use. Furthermore, the optical head is capable of measuring sub-atomic displacements of high-frequency AFM probes with a sub-micron laser spot (~570 nm, FWHM) and a high-working bandwidth (80 MHz). Nevertheless, conventional DVD optical heads suffer from signal drift problems. In a previous setup, signal drifts of even thousands of nanometers had been measured. With the anti-drift and auto-alignment mechanism, the signal drift is compensated by actuating a voice coil motor of the DVD optical head. A nearly zero signal drift was achieved. Additional benefits of this mechanism are automatic cantilever alignment and simplified design.

  2. Surgically induced astigmatism after phacoemulsification with and without correction for posture-related ocular cyclotorsion: randomized controlled study.

    LENUS (Irish Health Repository)

    Dooley, Ian

    2012-02-01

    PURPOSE: To report the impact of posture-related ocular cyclotorsion on one surgeon\\'s surgically induced astigmatism (SIA) results and the variance in SIA. SETTING: Institute of Eye Surgery, Whitfield Clinic, Waterford, Ireland. METHODS: This prospective randomized controlled study included eyes that had phacoemulsification with intraocular lens implantation. Eyes were randomly assigned to have (intervention group) or not have (control group) correction for posture-related ocular cyclotorsion. In the intervention group, the clear corneal incision was placed precisely at the 120-degree meridian with instruments designed to correct posture-related ocular cyclotorsion. In the control group, the surgeon endeavored to place the incision at the 120-degree meridian, but without markings. RESULTS: The intervention group comprised 41 eyes and the control group, 61 eyes. The mean absolute SIA was 0.74 diopters (D) in the intervention group and 0.78 D in the control group; the difference between groups was not statistically significant (P>.5, unpaired 2-tailed Student t test). The variance in SIA was 0.29 D(2) and 0.31 D(2), respectively; the difference between groups was not statistically significant (P>.5, unpaired F test). CONCLUSIONS: Attempts to correct for posture-related ocular cyclotorsion did not influence SIA or its variance in a single-surgeon series. These results should be interpreted with full appreciation of the limitations of currently available techniques to correct for posture-related ocular cyclotorsion in the clinical setting.

  3. [A comparative evaluation of astigmatic neutrality of 5 mm self-sealing tunnel incision of different types].

    Science.gov (United States)

    Avetisov, S E; Mamikonian, V R; Kas'ianov, A A

    2005-01-01

    The impact produced by incisions of 2 examined types on the corneal refraction was studied in 40 patients (40 eyes) shared between 2 groups according to an incision type. 5 mm tunnel self-sealing incisions of 2 types, i.e. temporal corneal one longer by 3 mm, and upper linear sclerocorneal one stabilized by horizontal suture, were made use of. The obtained refraction was evaluated on week 1 and then in 1 and 3 months after surgery. Group 1 (surgical approach: 5 mm linear sclerocorneal tunnel incision): the mean value of induced astigmatism made 0.68 D during the initial 3 postoperative days, 0.62 D in 1 month after surgery and 0.73 D in 3 months after surgery. Group 2 (surgical approach: 5 mm temporal corneal tunnel incision): the above value made 1.1 D during the initial 3 postoperative days, 0.7 D in one month after surgery and 0.52 D in 3 months.

  4. A numerical-experimental protocol to characterize corneal tissue with an application to predict astigmatic keratotomy surgery.

    Science.gov (United States)

    Ariza-Gracia, M Á; Ortillés, Á; Cristóbal, J Á; Rodríguez Matas, J F; Calvo, B

    2017-10-01

    Tonometers are intended to determine the intraocular pressure (IOP) and the quality of corneal tissue. In contrast to the physiological state of stress of the cornea, tonometers induce non-physiological bending stress. Recently, the use of a single experiment to calibrate a set of corneal mechanical properties was suggested to be an ill-posed problem. Thus, we propose a numerical-experimental protocol that uses inflation and indentation experiments simultaneously, restricting the optimization space to circumvent the ambiguity of the fitting. For the first time, both corneal behaviors, i.e., biaxial tension (physiological) and bending (non-physiological), are taken into account. The experimental protocol was performed using an animal model (New Zealand rabbit's cornea). The patient-specific geometry and IOP were registered using a MODI topographer (CSO, Italy) and an applanation tonometer, respectively. The mechanical response was evaluated using inflation and indentation experiments. Subsequently, the optimal set of material properties is identified via an inverse finite element method. To validate the methodology, an in vivo incisional refractive surgery (astigmatic keratotomy, AK) is performed on four animals. The optical outcomes showed a good agreement between the real and simulated surgeries, indicating that the protocol can provide a reliable set of mechanical properties that enables further applications and simulations. After a reliable ex vivo database of inflation experiments is built, our protocol could be extended to humans. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Keratometry versus total corneal refractive power: Analysis of measurement repeatability with 5 different devices in normal eyes with low astigmatism.

    Science.gov (United States)

    Fityo, Sylvia; Bühren, Jens; Shajari, Mehdi; Kohnen, Thomas

    2016-04-01

    To analyze the repeatability of corneal astigmatism measurements with 2 autokeratometers (IOLMaster 500 and Lenstar LS 900), 2 Placido topographers (Keratron Scout and Atlas 9000), and a Scheimpflug tomographer (Pentacam HR). Department of Ophthalmology, Goethe University, Frankfurt, Germany. Prospective case series. The inclusion criteria were a minimum age of 18 years, corneal astigmatism of 3.00 diopters or less, and patient's consent to participate in the study. The main exclusion criteria were corneal pathologies, trauma, previous surgery, hard contact lens wear in the previous 3 months, and soft contact lens wear in the previous 6 weeks. In addition to manifest refraction and visual acuity measurements, all subjects had 2 full measurements of 1 eye using each device. Anterior corneal astigmatism and total corneal refractive power via calculations derived from the Scheimpflug tomographer were evaluated. Statistical analysis was performed using the Bland-Altman method and multiple linear regression analysis. Forty-five eyes of 45 subjects (mean age 53.11 years ± 10.43 [SD]; 23 left eyes; 33 women) were included. The mean intermeasurement differences were approximately zero for all devices. The relative coefficient of repeatability of anterior corneal astigmatism, steep axis, and the vector analysis parameter J180 were lowest with the Scheimpflug tomographer. Total corneal refractive power measured with the Scheimpflug tomographer showed the highest repeatability in the larger diameter zones. The Scheimpflug tomographer yielded higher repeatability of corneal astigmatism measurements, with total corneal refractive power measurements being as repeatable as established metrics. Dr. Kohnen receives research support from Abbott Medical Optics Inc., Alcon Pharma GmbH, Bausch & Lomb GmbH, Carl Zeiss Meditec Vertriebsgesellschaft mbH, Hoya Surgical Optics GmbH, Oculus Optikgeräte GmbH, and Schwind eye-tech-solutions GmbH and Co. KG. He receives travel

  6. Topography-guided hyperopic and hyperopic astigmatism femtosecond laser-assisted LASIK: long-term experience with the 400 Hz eye-Q excimer platform

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2012-06-01

    Full Text Available Anastasios John KanellopoulosDepartment of Ophthalmology, New York University Medical School, New York, NY, and LaserVision.gr Eye Institute, Athens, GreeceBackground: The purpose of this study was to evaluate the safety and efficacy of topography-guided ablation using the WaveLight 400 Hz excimer laser in laser-assisted in situ keratomileusis (LASIK for hyperopia and/or hyperopic astigmatism.Methods: We prospectively evaluated 208 consecutive LASIK cases for hyperopia with or without astigmatism using the topography-guided platform of the 400 Hz Eye-Q excimer system. The mean preoperative sphere value was +3.04 ± 1.75 (range 0.75–7.25 diopters (D and the mean cylinder value was –1.24 ± 1.41 (–4.75–0 D. Flaps were created either with Intralase FS60 (AMO, Irvine, CA or FS200 (Alcon, Fort Worth, TX femtosecond lasers. Parameters evaluated included age, preoperative and postoperative refractive error, uncorrected distance visual acuity, corrected distance visual acuity, flap diameter and thickness, topographic changes, higher order aberration changes, and low contrast sensitivity. These measurements were repeated postoperatively at regular intervals for at least 24 months.Results: Two hundred and two eyes were available for follow-up at 24 months. Uncorrected distance visual acuity improved from 5.5/10 to 9.2/10. At 24 (8–37 months, 75.5% of the eyes were in the ±0.50 D range and 94.4% were in the ±1.00 D range of the refractive goal. Postoperatively, the mean sphere value was –0.39 ± 0.3 and the cylinder value was –0.35 ± 0.25. Topographic evidence showed that ablation was made in the visual axis and not in the center of the cornea, thus correlating with the angle kappa. No significant complications were encountered in this small group of patients.Conclusion: Hyperopic LASIK utilizing the topography-guided platform of the 400 Hz Eye-Q Allegretto excimer and a femtosecond laser flap appears to be safe and effective for

  7. Astigmatismo induzido na cirurgia extracapsular da catarata: acompanhamento a longo prazo Induced astigmatism in extracapsular cataract extraction: long-term follow-up

    Directory of Open Access Journals (Sweden)

    Almir Ghiaroni

    2004-02-01

    Full Text Available OBJETIVO: Estudar o comportamento do astigmatismo induzido a longo prazo em uma série de pacientes submetidos à cirurgia extracapsular da catarata, nos quais foi utilizada incisão límbica posterior superior suturada com pontos separados de mononylon 10-0. MÉTODOS: Foram estudados 38 olhos, de 35 pacientes, sendo 21 do sexo feminino e 14 do sexo masculino, com idades variando entre 47 e 85 anos (média = 70,17 anos. Todos os casos foram operados pelo mesmo cirurgião. O período de acompanhamento pós-operatório variou de 15 a 33 meses (média = 22,07 meses. Nenhum dos casos teve qualquer dos pontos seccionado ou removido. Todos os pacientes atingiram acuidade visual corrigida igual ou superior a 0,5. Para o cálculo do astigmatismo induzido foram consideradas as medidas ceratométricas pré e pós-operatórias e foi utilizado um programa desenvolvido por Jaffe. RESULTADOS: O astigmatismo induzido variou de 0,13 dioptria (D a 2,74 D (média = 1,19 D. Em relação aos eixos, na maioria dos casos houve indução de astigmatismo a favor da regra (60,52%. Foi observada mudança significativa no valor dióptrico do astigmatismo quando foram comparadas as leituras ceratométricas registradas pré-operatoriamente até a segunda semana pós-operatória, entre o primeiro e o terceiro meses pós-operatórios, entre o terceiro e o sexto meses pós-operatórios e após o décimo-segundo mês pós-operatório. CONCLUSÃO: Quando o mononylon 10-0 é utilizado como material de sutura na cirurgia extracapsular da catarata, os valores de astigmatismo a favor da regra inicialmente observados tendem a diminuir com o tempo.PURPOSE: To study the long-term behavior of induced astigmatism in a series of patients who underwent extracapsular extraction in which a superoposterior limbal incision sutured with interrupted 10-0 mononylon sutures was performed. METHODS: 38 eyes of 35 patients were studied, 21 females and 17 males, with ages varying from 47 to 85 year

  8. Corneal astigmatism correction with scleral flaps in trans-scleral suture-fixed posterior chamber lens implantation: a preliminary clinical observation.

    Science.gov (United States)

    Ma, Li-Wei; Xuan, Dwight; Li, Xiao-Yan; Zhang, Jin-Song

    2011-01-01

    To study the impact of scleral flap position, under which the posterior chamber intraocular lenses (PC-IOL) were sulcus-fixed by trans-scleral suture, on cornea astigmatism. Twenty-six aphakic or cataract eyes were comprised in this prospective noncomparative case series study. Eleven eyes had traumatic cataract removed without sufficient capsular support, 3 had blunt trauma with subluxated traumatic cataract, 8 had undergone vitreoretinal surgery and 4 had congenital cataract removed. The average age was 54 years (range 21-74 years), with 17 men and 7 women. The foldable PC-IOL was fixed in sulcus by trans-scleral suture. The incision for IOL implantation was made 1mm posterior to limbus along the steepest meridian of cornea, while scleral flaps to bury the knots of trans-scleral suture were made along the flattest meridian. All the surgeries were performed by a single doctor (Ma L), and the follow up was at least 13 months (range 13-28 months). The preoperative, 3 months and 1 year postoperative corneal curvature along the steepest and flattest cornea meridian and overall cornea astigmatism were compared. The curvature along the steepest meridian changed from 44.25±2.22D preoperatively to 44.08±2.16D at 3 months postoperatively, and 43.65±5.23D at 1 year postoperatively (P>0.05); the curvature along the flattest meridian changed from 41.24±2.21D preoperatively to 43.15±3.94D at 3 months postoperatively, and 42.85±5.17D at 1 year postoperatively (Pastigmatism (SIA) on cornea was calculated by vector analysis, which was 2.42±2.13D at 3 months postoperatively, and 2.18±3.42D at 1 year postoperatively, the difference was statistically significant (Psuture, can steepen the cornea in varying degrees, thus reducing preexisting corneal astigmatism.

  9. Anisometropia of spherical equivalent and astigmatism among myopes: a 23-year follow-up study of prevalence and changes from childhood to adulthood.

    Science.gov (United States)

    Pärssinen, Olavi; Kauppinen, Markku

    2017-08-01

    To study anisometropia of spherical equivalent and astigmatism from the onset of myopia at school age to adulthood. A total of 240 myopic schoolchildren (mean age 10.9 years), with no previous spectacles, were recruited during 1983-1984 to a randomized 3-year clinical trial of bifocal treatment of myopia. Examinations with subjective cyclopedic refraction were repeated 3 years later (follow-up 1) for 238 subjects and thereafter at the mean ages of 23.2 (follow-up 2) and 33.9 years (follow-up 3) for 178 and 134 subjects. After exclusions, the 102 subjects who attended all three follow-ups were included in the analyses. Corneal refractive power and astigmatism and anterior chamber depth was measured with Pentacam topography and axial length with IOL master at study end. Prevalence and changes in anisometropia of spherical equivalent (AnisoSE) and astigmatism (AnisoAST) and their relationships with refractive and axial measures were studied. Mean (±SD) of spherical equivalent (SE), AnisoSE and AnisoAST increased from baseline to follow-up end from -1.44 ± 0.57 D to -5.11 ± 2.23 D, from 0.28 ± 0.30 D to 0.68 ± 0.69 D and from 0.14 ± 0.18 D to 0.37 ± 0.36 D, respectively. Prevalence of AnioSE, ≥1 D, increased from 5% to 22.6% throughout follow-up. Higher AnisoSE was associated with SE in the less myopic eye at baseline and at follow-up 1, and with SE in the more myopic eye in follow-ups 2 and 3 in adulthood. At study end, AnisoSE was associated with the interocular difference in axial length (AL) (r = 0.612, p Anisometropia of the spherical equivalent (AnisoSE) increased along with the myopic progression and at study end was mainly associated with the interocular difference in AL. AnisoAST was mainly explained by the interocular difference in corneal astigmatism. In cases with low AnisoSE (≤1.0 D), the interrelationship between CR and AL decreased AnisoSE causing emmetropization in AnisoSE. © 2017 Acta Ophthalmologica Scandinavica

  10. Repeatability and comparability of corneal power and corneal astigmatism obtained from a point-source color light-emitting diode topographer, a Placido-based corneal topographer, and a low-coherence reflectometer.

    Science.gov (United States)

    Ventura, Bruna V; Al-Mohtaseb, Zaina; Wang, Li; Koch, Douglas D; Weikert, Mitchell P

    2015-10-01

    To assess the repeatability and agreement of corneal power and astigmatism obtained from the Cassini point-source color light-emitting diode (LED) topographer, Humphrey Atlas 9000 Placido-based corneal topographer, and Lenstar LS-900 low-coherence reflectometer in normal eyes. Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. Evaluation of diagnostic test or technology. Consecutively enrolled patients with normal corneas were enrolled. Three sets of measurements were obtained using the color-LED topographer, the Placido topographer, and the reflectometer. Vector analysis was used in the astigmatism analysis. The repeatability was evaluated using the within-subject standard deviation, coefficient of variation (CoV), and intraclass correlation coefficient (ICC). Agreement was verified using Bland-Altman plots. The paired Student t test was used to assess statistical significance. Thirty-two eyes (32 patients) were evaluated. All devices provided highly repeatable corneal power and astigmatism measurements (ICC > 0.9) except for the Placido topographer with regard to J45 (ICC = 0.721). The color-LED topographer and the reflectometer obtained similar mean values of corneal power, astigmatism magnitude, J0, and J45 (P > .05), which was also true when comparing the color-LED topographer and the Placido topographer, except for the mean corneal power (P = .0007). The Bland-Altman plots showed a wide data spread for all analyzed variables. The color-LED topographer provided highly repeatable corneal power and astigmatism measurements. Even though it obtained values similar to those of the reflectometer and the Placido topographer, the wide data spread discourages their interchangeable use to assess corneal power and astigmatism. Drs. Wang, Koch, and Weikert are consultants to Ziemer USA, Inc. Dr. Koch is a consultant to Abbott Medical Optics, Inc., Alcon Surgical, Inc., and i-Optics, Corp. Drs. Ventura and Al-Mohtaseb have no financial or proprietary

  11. Long-Term Outcomes of Radial Keratotomy, Laser In Situ Keratomileusis, and Astigmatic Keratotomy Performed Consecutively over a Period of 21 Years

    Directory of Open Access Journals (Sweden)

    Priyanka Chhadva

    2015-01-01

    Full Text Available Purpose. To describe a case of 3 refractive procedures performed in one eye over 2 decades. Methods. Case report. Results. A 41-year-old patient presented for refractive surgery evaluation. His ocular history includes bilateral radial keratotomy performed 21 years ago for moderate myopia: spherical equivalence of −4.25 D bilaterally. Postoperative uncorrected visual acuity (UCVA was 20/30; however, over time he developed a hyperopic shift and UCVA decreased to 20/40 in the right eye. Thus, laser-assisted in situ keratomileusis (LASIK was performed at an outside institution 6.5 years later, and the patient had initial improvement of UCVA to 20/25. Due to a change in refractive error, the patient underwent uneventful astigmatic keratotomy 13 years after LASIK in the right eye, and 1.5 years after surgery best-corrected visual acuity was 20/25 with manifest refraction of −1.00+5.50×134°.  Conclusion. We report the outcomes and natural refractive progression in a patient who underwent three corneal refractive procedures over two decades. This case underlines the difficulties of long-term management of post-RK hyperopia and astigmatism.

  12. Combined Descemet-stripping automated endothelial keratoplasty and phacoemulsification with toric intraocular lens implantation for treatment of failed penetrating keratoplasty with high regular astigmatism.

    Science.gov (United States)

    Scorcia, Vincenzo; Lucisano, Andrea; Beltz, Jacqueline; Busin, Massimo

    2012-04-01

    We present the case of a 57-year-old woman who had combined Descemet-stripping automated endothelial keratoplasty (DSAEK) and phacoemulsification with implantation of a toric intraocular lens (IOL). Surgery was intended to treat a cataract developing in a post-penetrating keratoplasty (PKP) eye with high astigmatism and endothelial decompensation. Six months after uneventful surgery, the cornea was clear and the corrected distance visual acuity was 20/20 with a refraction of +0.25 -1.00 × 10 (from -3.00 -8.50 × 12 preoperatively). The internal topography map (OPD-Scan) showed an IOL rotation of 4 degrees. The endothelial cell loss was 15% of the eye-bank value. Descemet-stripping automated endothelial keratoplasty combined with phacoemulsification and toric IOL implantation is a relatively simple and very effective procedure for eyes with endothelial failure and high post-PKP astigmatism. The speed of visual rehabilitation and final visual acuity achieved with this approach was superior to that obtained with other surgical procedures. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  13. Utility of orthokeratology contact lenses; efficacy of myopia correction and level of patient satisfaction in Iranian myopic/myope-astigmatic patients.

    Science.gov (United States)

    Rajabi, Mohammad Taher; Hosseini, Seyedeh Simindokht; Ghorbani, Zahra; Nobahari, Fereshteh; Bazvand, Fatemeh; Doostdar, Askar; Zarrinbakhsh, Parviz; Rajabi, Mohammad Bagher

    2015-01-01

    To investigate the medical profiles of patients referred to Iran Lens Clinic with myopic/myope-astigmatic refractive errors. Medical records of 182 patients (364 eyes) with myopic/myope-astigmatic refractive errors that underwent orthokeratology contact lens wear and fulfilled a 6-month period of follow-up were recruited. Efficacy and safety of these contact lenses in improving the visual acuity and correction of the refractive errors were investigated. Time needed to achieve final targeted visual acuity and association of various factors in this time course and level of acuity were investigated. Complications related to these lenses that were recorded in the medical profiles were studied. In manifest refraction, the amount of spherical equivalent and myopia decreased significantly after orthokeratology contact lens wear (P gender, and keratometric findings influenced the outcomes significantly (P > 0.1). Patients with myopic refractive error lower than -5.0 Diopters achieved higher final visual acuities rather than patients with higher amounts of myopic refractive errors.

  14. Combined special capsular tension ring and toric IOL implantation for management of post-DALK high regular astigmatism with subluxated traumatic cataract

    Directory of Open Access Journals (Sweden)

    Asim Kumar Kandar

    2014-01-01

    Full Text Available We report a case of 18-year-old male who has undergone phacoemulsification with implantation of toric IOL (AcrySof IQ SN6AT9 after fixation of lens capsule with Cionni′s capsular tension ring (CTR for subluxated traumatic cataract with high astigmatism after deep anterior lamellar keratoplasty (DALK. He underwent right eye DALK for advanced keratoconus four years earlier. He had history of trauma one year later with displaced clear crystalline lens into  anterior chamber and graft dehiscence, which was repaired successfully. The graft survived, but patient developed cataract with subluxated lens, for which phacoemulsification with implantation of toric IOL was done. Serial  topography showed regular corneal astigmatism of -5.50 diopter (K 1 42.75 D @130°, K 2 48.25 D @40°. At 10-month follow-up, the patient has BCVA 20/30 with + 0.75 DS/- 1.75 DC @ 110°. The capsular bag is quite stable with well-centered IOL. Combination of Cionni′s ring with toric IOL could be a good option to manage such complex cases.

  15. Facts about Astigmatism

    Science.gov (United States)

    ... Science Communication dustin.hays@nih.gov Anna Harper - Media Relations afh@nei.nih.gov NEI Office of Communications (301)496-5248 Health Information Frequently asked questions Clinical Studies Publications Catalog Photos ...

  16. Safety, Efficacy, Predictability and Stability Indices of Photorefractive Keratectomy for Correction of Myopic Astigmatism with Plano-Scan and Tissue-Saving Algorithms

    Directory of Open Access Journals (Sweden)

    Mehrdad Mohammadpour

    2013-10-01

    Full Text Available Purpose: To assess the safety, efficacy and predictability of photorefractive keratectomy (PRK [Tissue-saving (TS versus Plano-scan (PS ablation algorithms] of Technolas 217z excimer laser for correction of myopic astigmatismMethods: In this retrospective study one hundred and seventy eyes of 85 patients (107 eyes (62.9% with PS and 63 eyes (37.1% with TS algorithm were included. TS algorithm was applied for those with central corneal thickness less than 500 µm or estimated residual stromal thickness less than 420 µm. Mitomycin C (MMC was applied for 120 eyes (70.6%; in case of an ablation depth more than 60 μm and/or astigmatic correction more than one diopter (D. Mean sphere, cylinder, spherical equivalent (SE refraction, uncorrected visual acuity (UCVA, best corrected visual acuity (BCVA were measured preoperatively, and 4 weeks,12 weeks and 24 weeks postoperatively.Results: One, three and six months postoperatively, 60%, 92.9%, 97.5% of eyes had UCVA of 20/20 or better, respectively. Mean preoperative and 1, 3, 6 months postoperative SE were -3.48±1.28 D (-1.00 to -8.75, -0.08±0.62D, -0.02±0.57 and -0.004± 0.29, respectively. And also, 87.6%, 94.1% and 100% were within ±1.0 D of emmetropia and 68.2, 75.3, 95% were within ±0.5 of emmetropia. The safety and efficacy indices were 0.99 and 0.99 at 12 weeks and 1.009 and 0.99 at 24 weeks, respectively. There was no clinically or statistically significant difference between the outcomes of PS or TS algorithms or between those with or without MMC in either group in terms of safety, efficacy, predictability or stability. Dividing the eyes with subjective SE≤4 D and SE≥4 D postoperatively, there was no significant difference between the predictability of the two groups. There was no intra- or postoperative complication.Conclusion: Outcomes of PRK for correction of myopic astigmatism showed great promise with both PS and TS algorithms.

  17. Simultaneous three-dimensional temperature and velocity field measurements using astigmatic imaging of non-encapsulated thermo-liquid crystal (TLC) particles.

    Science.gov (United States)

    Segura, Rodrigo; Rossi, Massimiliano; Cierpka, Christian; Kähler, Christian J

    2015-02-07

    A combination of cutting edge developments is presented to characterize three-dimensional (3D) temperature and velocity fields in microscopic flows. An emulsion of non-encapsulated thermo-liquid crystal (TLC) micro spheres, with a narrow size distribution is used to track the flow's motion and temperature distribution. A state-of-the-art light engine, which combines the spectrum of six light pipes, provides a balanced illumination which allows for strong and detectable color patterns across the TLC's temperature response range. Lastly, the ability of the TLC material to reflect select wavelength bands with an unchanging and independent circular polarization chirality is exploited by a filter that blocks background noise, while exclusively transmitting the color signal of the TLC particles. This approach takes advantage of the peculiar physical properties of TLCs to allow the estimation of individual TLC particle's 3D position, for the first time, using Astigmatism Particle Tracking Velocimetry (APTV).

  18. Academic and Workplace-related Visual Stresses Induce Detectable Deterioration Of Performance, Measured By Basketball Trajectories and Astigmatism Impacting Athletes Or Students In Military Pilot Training.

    Science.gov (United States)

    Mc Leod, Roger D.

    2004-03-01

    Separate military establishments across the globe can confirm that a high percentage of their prospective pilots-in-training are no longer visually fit to continue the flight training portion of their programs once their academic coursework is completed. I maintain that the visual stress induced by those intensive protocols can damage the visual feedback mechanism of any healthy and dynamic system beyond its usual and ordinary ability to self-correct minor visual loss of acuity. This deficiency seems to be detectable among collegiate and university athletes by direct observation of the height of the trajectory arc of a basketball's flight. As a particular athlete becomes increasingly stressed by academic constraints requiring long periods of concentrated reading under highly static angular convergence of the eyes, along with unfavorable illumination and viewing conditions, eyesight does deteriorate. I maintain that induced astigmatism is a primary culprit because of the evidence of that basketball's trajectory! See the next papers!

  19. Laser in situ keratomileusis with a scanning excimer laser for the correction of low to moderate myopia with and without astigmatism.

    Science.gov (United States)

    Balazsi, G; Mullie, M; Lasswell, L; Lee, P A; Duh, Y J

    2001-12-01

    To evaluate the safety and effectiveness of and patient satisfaction with laser in situ keratomileusis (LASIK) performed with a scanning excimer laser by experienced surgeons to correct low and moderate levels of myopia and astigmatism. Clinique Laservue, Montreal, Quebec, Canada. A consecutive series of 125 patients (236 eyes) with myopia of -0.5 to -7.0 diopters (D) and cylinder less than 2.5 D were enrolled in this single-center prospective clinical trial. The patients were treated with LASIK and followed for 6 months. The System-ALK Automated Corneal Shaper microkeratome (Bausch & Lomb Surgical) with a 180 microm thickness plate and the Technolas 217 excimer laser (Bausch & Lomb Surgical) with PlanoScan software for the stromal ablation were used in all procedures. Since this version of PlanoScan tended to undercorrect, a mean of 14.7% was added to the standard nomogram. Patient satisfaction was assessed by questionnaires administered preoperatively and 1 and 6 months postoperatively. Retreatments for enhancement were not performed during the 6-month follow-up. Six months after LASIK (86.4% follow-up), the mean postoperative manifest spherical equivalent was +0.02 D +/- 0.64 (SD) compared with a preoperative mean of -4.01 +/- 1.59 D. The uncorrected visual acuity was 20/40 or better in 94.6% of eyes and 20/20 or better in 81.9%. A total of 91.2% were within +/-1.0 D of emmetropia and 73.0% were within +/-0.5 D. Only 2 eyes were overcorrected by >1.0 D. Of the eyes with astigmatic myopia, 86.8% were within +/-1.0 D of the intended cylinder correction (by vector analysis) and 73.0% were within +/-0.5 D. The refractions were generally stable after 1 month, and the change in refraction between postoperative examinations was within +/-0.5 D in 88.0% of eyes. A 1-line decrease in best spectacle-corrected visual acuity was seen in 11.3% of eyes, and no eye lost more than 1 line. An increase of 1 or 2 lines was seen in 45.1%. No intraoperative problems occurred, and

  20. Delaminação límbica: uma nova técnica para correção de astigmatismo pós-transplante Limbal delamination: a new technique for postkeratoplasty astigmatism correction

    Directory of Open Access Journals (Sweden)

    Sandro Antonini Coscarelli

    2003-01-01

    Full Text Available OBJETIVO: Avaliar segurança e eficácia da técnica de delaminação límbica para correção de astigmatismos pós-transplantes. MÉTODOS: Cinco pacientes, sendo três do sexo feminino e dois do sexo masculino com idades entre 21 e 42 anos, apresentando erros de refração e enxerto transparente após transplante penetrante, foram submetidos à delaminação límbica. RESULTADOS: Em um ano de acompanhamento, os enxertos permaneceram transparentes e o astigmatismo foi reduzido em média de 3,80 dioptrias cilíndricas. CONCLUSÃO: A delaminação límbica mostrou-se técnica eficiente para correção dos astigmatismos pós-transplante.PURPOSE: To evaluate safety and efficacy of limbal delamination management for post-keratoplasty astigmatism correction. METHODS: Five patients, three women and two men, between 21 and 42 years old, who showed refractive errors with a transparent cornea after penetrating keratoplasty were submitted to the technique. RESULTS: After a 12-month follow-up the graft remained transparent. Astigmatism was reduced to an average of 3.80 cylindric dioptries. CONCLUSION: Limbal delamination management seems to be an effective technique to correct astigmatism after successful penetrating keratoplasty.

  1. Neck/shoulder discomfort due to visually demanding experimental near work is influenced by previous neck pain, task duration, astigmatism, internal eye discomfort and accommodation.

    Science.gov (United States)

    Zetterberg, Camilla; Forsman, Mikael; Richter, Hans O

    2017-01-01

    Visually demanding near work can cause eye discomfort, and eye and neck/shoulder discomfort during, e.g., computer work are associated. To investigate direct effects of experimental near work on eye and neck/shoulder discomfort, 33 individuals with chronic neck pain and 33 healthy control subjects performed a visual task four times using four different trial lenses (referred to as four different viewing conditions), and they rated eye and neck/shoulder discomfort at baseline and after each task. Since symptoms of eye discomfort may differ depending on the underlying cause, two categories were used; internal eye discomfort, such as ache and strain, that may be caused by accommodative or vergence stress; and external eye discomfort, such as burning and smarting, that may be caused by dry-eye disorders. The cumulative performance time (reflected in the temporal order of the tasks), astigmatism, accommodation response and concurrent symptoms of internal eye discomfort all aggravated neck/shoulder discomfort, but there was no significant effect of external eye discomfort. There was also an interaction effect between the temporal order and internal eye discomfort: participants with a greater mean increase in internal eye discomfort also developed more neck/shoulder discomfort with time. Since moderate musculoskeletal symptoms are a risk factor for more severe symptoms, it is important to ensure a good visual environment in occupations involving visually demanding near work.

  2. Study on the distribution of the dominant eye in people with myopia and astigmatism and the relationship between dominant eye and the two

    Directory of Open Access Journals (Sweden)

    Wen-Li Duan

    2015-11-01

    Full Text Available AIM:To study the distribution of the dominant eye in people with myopia and astigmatism and the relationship between dominant eye and the two. METHODS:Three hundred and eighty patients who went our hospital for optometry consecutively were enrolled, using hole-in-card method to detect the dominant eye. The records of age, gender, vision acuity and other related information were analyzed by SPSS 11.0 software. RESULTS: 1Most of the dominant eyes were right eyes which accounted for 66.84%, and the ametropia degree on right eyes was relatively higher; 2Dominant eyes had no significant association with gender, age and uncorrected vision acuity(P>0.05; 3There was no significant correlation between the dominant eyes and ametropia degree(P>0.05. But in the group which the difference of cylinder degree between two eyes were ≥1D, only 20% of the dominant eyes had higher ametropia degree, which was different from the other two groups. CONCLUSION:High cylinder of anisometropia may affect the choice of the dominant eye. High sphere of anisometropia may be the result of the choice of dominant eye.

  3. Neck/shoulder discomfort due to visually demanding experimental near work is influenced by previous neck pain, task duration, astigmatism, internal eye discomfort and accommodation.

    Directory of Open Access Journals (Sweden)

    Camilla Zetterberg

    Full Text Available Visually demanding near work can cause eye discomfort, and eye and neck/shoulder discomfort during, e.g., computer work are associated. To investigate direct effects of experimental near work on eye and neck/shoulder discomfort, 33 individuals with chronic neck pain and 33 healthy control subjects performed a visual task four times using four different trial lenses (referred to as four different viewing conditions, and they rated eye and neck/shoulder discomfort at baseline and after each task. Since symptoms of eye discomfort may differ depending on the underlying cause, two categories were used; internal eye discomfort, such as ache and strain, that may be caused by accommodative or vergence stress; and external eye discomfort, such as burning and smarting, that may be caused by dry-eye disorders. The cumulative performance time (reflected in the temporal order of the tasks, astigmatism, accommodation response and concurrent symptoms of internal eye discomfort all aggravated neck/shoulder discomfort, but there was no significant effect of external eye discomfort. There was also an interaction effect between the temporal order and internal eye discomfort: participants with a greater mean increase in internal eye discomfort also developed more neck/shoulder discomfort with time. Since moderate musculoskeletal symptoms are a risk factor for more severe symptoms, it is important to ensure a good visual environment in occupations involving visually demanding near work.

  4. Long-term results of photorefractive keratectomy for myopia and myopic astigmatism Resultados a longo prazo de ceratectomia fotorefrativa para miopia e astigmatismo miópico

    Directory of Open Access Journals (Sweden)

    Ester Sakae Yamazaki

    2007-12-01

    Full Text Available PURPOSE: To assess the long-term refractive outcomes of photorefractive keratectomy in myopia and myopic astigmatism. METHODS: A retrospective study of 120 photorefractive keratectomy operated eyes with at least four-year follow-up (maximum of 96 months, mean follow-up 55 months. We divided patients into group 1 (G1 spherical equivalent (SE up to -4.00 diopters (D and group 2 (G2 SE >-4.00 D. The Summit Apex Plus® excimer laser was used for ablation. All eyes were analyzed in terms of uncorrected and best spectacle corrected visual acuity (UCVA/BSCVA and cycloplegic refraction. Data were analyzed using the Refractive Surgery Consultant Elite database software. RESULTS: G1 with 85 eyes (49 patients presented mean SE -2.42 D and G2 with 35 eyes (22 patients and mean SE of -4.45 D. Ninety-four percent of eyes in G1 and 82.9% of G2 were within ±1.00 D of emmetropia at 4 years. The UCVA was 20/30 or better in 82.0% of G1 eyes and 77.0% of G2 in the last postoperative follow-up. No patient lost more than one line in G2 compared to 13.0% in G1. Eyes that gained one or more lines after 4-year follow-up were 11.9% G1 and 2.9% in G2, respectively. A statistically significant positive correlation was found between achieved versus attempted refractive correction in both groups (r=0.925, pOBJETIVO: Relatar os resultados a longo prazo da cirurgia de ceratectomia fotorefrativa em miopia e astigmatismo miópico. MÉTODOS: Estudo retrospectivo de120 olhos operados de ceratectomia fotorefrativa com um mínimo intervalo de 4 anos de seguimento pós-operatório (máximo de 96 meses e seguimento médio de 55 meses. Dividimos em grupo 1 (G1 com equivalente esférico (SE até -4.00 dioptrias (D e grupo 2(G2 SE > -4.00 D. O excimer laser Summit Apex Plus® foi usado na ablação. Foram obtidas acuidade visual não corrigida (UCVA e melhor acuidade visual corrigida (BSCVA e refração sob cicloplegia. Os dados foram analisados utilizando o programa Refractive Surgery

  5. Ceratectomia fotorrefrativa (PRK com mitomicina C a 0,02% para correção de grau acentuado de astigmatismo hipermetrópico composto secundário a cirurgia de ceratotomia radial (RK Photorefractive keratectomy (PRK with mitomicyn C 0,02% for the management of high degree of hyperopic astigmatism following radial keratectomy

    Directory of Open Access Journals (Sweden)

    Adamo Lui Netto

    2009-06-01

    Full Text Available Descrever o efeito da cirurgia fotorrefrativa (PRK associada ao uso de mitomicina C a 0,02% para correção de grau acentuado de astigmatismo hipermetrópico composto apresentado após cirurgia de ceratotomia radial (RK realizada há 12 anos.To describe PRK with mitomicyn C effects for the management of high-degree hyperopic astigmatism following Radial Keratectomy performed 12 years ago.

  6. Lente de contato de material híbrido em pacientes com ceratocone e astigmatismo miópico composto Hybrid material contact lens in keratoconus and myopic astigmatism patients

    Directory of Open Access Journals (Sweden)

    Fernando Leal

    2007-03-01

    óculos, exceto para a freqüência B (3 cpg, maior nos usuários de óculos. As aberrações de alta ordem analisadas apresentaram diminuição estatisticamente significante, quando comparados os pacientes sem e com uso de lentes de contato, com exceção da aberração esférica e do coma. CONCLUSÃO: A lente de contato de material híbrido, quando utilizada por portadores de ceratocone e astigmatismo miópico composto, propiciaram desempenho visual e conforto satisfatórios, em níveis que não diferiram, das lentes de contato rígidas-gás-permeáveis nos dois grupos de pacientes.PURPOSE: To evaluate comfort and visual performance in relation to two different used contact lens types: hybrid material (HM and rigid-gas-permeable (RGP, in patients with regular myopic astigmatism and with keratoconus. METHODS: A randomized, double masked, prospective study of 22 patients with the diagnosis of myopic astigmatism (8 with myopic astigmatism and 14 with keratoconus was conducted. Fifteen patients were female and 7 were male, and mean age was: 32.13 ± 8.12 years. In one of the eyes a rigid-gas-permeable contact lens was adapted (DK 30, and in the other a hybrid material contact lens was adapted (DK 23. All patients were submitted to the following tests: measurement of comfort level by means of the analogical visual scale, tear break-up time, best corrected visual acuity with the Bailey-Lovie scale adapted for 4 meters, functional acuity contrast test (FACT and wavefront analysis. RESULTS: In relation to comfort, there was no association with the evaluated contact lens type (p=0.350. There was a variation in comfort level during the first 7 days. The visual acuity increased between the 7th and the 15th day of adaptation. Visual acuity stabilized right after this period. The visual acuity did not show differences in relation to the studied lens type. It was verified that there was no difference in the tear break-up time (p=0.989 in relation to the studied lenses type and

  7. Posição viciosa de cabeça por astigmatismo mal corrigido: relato de caso Abnormal head position caused by incorrect prescription for astigmatism: case report

    Directory of Open Access Journals (Sweden)

    Flávia Augusta Attié de Castro

    2005-10-01

    Full Text Available A posição viciosa de cabeça é uma condição compensatória que visa proporcionar aos pacientes melhor rendimento visual. Pode ser causada por problemas oftalmológicos, como distúrbios oculomotores (nistagmos, estrabismos e altos astigmatismos. No entanto, compromete a estética e, a longo prazo, pode causar transtornos ortopédicos (coluna cervical e assimetrias faciais. Relatamos o caso de uma garota, JL, 8 anos, com cabeça inclinada para esquerda havia vários anos. Fazia uso de óculos prescritos em outro serviço para correção de astigmatismo misto: OD= +2,00 DE Ç -5,50 DC a 180º e OE= +2,25 DE Ç -5,75 DC a 180º. No exame oftálmico, a paciente apresentava cabeça inclinada para a esquerda e acuidade visual com correção de 0,5 no OD e 0,7 OE. Os testes de cobertura simples e alternado não evidenciaram desvio ocular. Rotações oculares, biomicroscopia e fundoscopia também não mostraram alterações. Na refratometria sob cicloplegia e teste de lentes foram encontrados: OD= +3,50 DE Ç -6,00 DC a 10º e OE= +3,50 DE Ç -6,00 DC a 170º, com acuidade visual igual a 1,0 nos olhos direito e esquerdo. Foram prescritas as lentes encontradas no exame e a paciente retornou com a correção nova sem a inclinação de cabeça. Erros refracionais mal corrigidos também podem gerar torcicolo e, muitas vezes, passam despercebidos. Refratometria sob cicloplegia e teste de lentes são fundamentais para um diagnóstico preciso.Abnormal head position is a compensatory condition which improves patients' vision. It can be caused by ophthalmological problems such as oculomotor imbalances (strabismus, nystagmus and high astigmatisms. However, it results in esthetic impairment, orthopedic trouble and facial asymmetries. We describe a case of a girl, JL, 8 years, with abnormal head position tilted to the left since the last glasses were prescribed. The correction used by the patient was: right eye = +2.00 sph à -5.5 cyl 180° and left eye = +2

  8. Efeito da remoção seletiva da sutura no astigmatismo nos transplantes de córnea pós-ceratocone The effect of selective suture removal on astigmatism following penetrating keratoplasty in keratoconus

    Directory of Open Access Journals (Sweden)

    Fernando Moro

    2007-10-01

    Full Text Available OBJETIVO: Demonstrar o efeito e os resultados da remoção seletiva da sutura sobre o astigmatismo nos três primeiros meses de transplante de córnea pós-ceratocone. MÉTODOS: Realizamos um estudo longitudinal observacional retrospectivo, revisando aleatoriamente os prontuários médicos de 50 pacientes, submetidos à transplante penetrante de córnea por ceratocone, realizados pelo mesmo cirurgião, no período entre 2000 e 2002, no Instituto de Oftalmologia Tadeu Cvintal. Os transplantes foram realizados com a mesma técnica cirúrgica com oito pontos isolados e sutura contínua e controle ceratoscópico per-operatório. Em todas as visitas foram mensuradas a melhor acuidade visual corrigida, ceratometria e refração. A remoção seletiva da sutura e redistribuição da sutura contínua ocorreu invariavelmente no primeiro mês de pós-operatório. RESULTADOS: No primeiro mês de pós-operatório, antes do início de remoção de suturas a acuidade visual média pré-remoção foi de 0,4 log MAR. Após remoção seletiva escalonada de suturas e estabilização do astigmatismo, a acuidade visual média pós-remoção foi de 0,07 log MAR, diferença estatisticamente significativa (pPURPOSE: To analyse the corneal astigmatism after transplantation as well as to demonstrate how post-surgical handling of sutures affects the refractive and visual outcome in patients submitted to cornea transplantation by keratoconus with three to six years of follow-up. METHODS: Non-controlled longitudinal observational secondary clinical study. Fifty records of patients submitted to penetrating keratoplasty between 2000 and 2002 have been reviewed, including 50 eyes of 50 patients operated under the same surgical technique by the same surgeon. Follow-up time ranging from three to six years. Main outcome measures were keratometry, static refraction and computadorized keratometry. Tstudent and Wilcoxon tests were used for paired samples to assess respectively

  9. Measurement of astigmatism by automated infrared photoretinoscopy.

    Science.gov (United States)

    Gekeler, F; Schaeffel, F; Howland, H C; Wattam-Bell, J

    1997-07-01

    There are basically two possibilities to measure cylindrical refractive errors by eccentric photorefraction. The first is to determine the size and the tilt of the light crescent in the subject's pupil. Sphere, cylinder, and axis can be obtained from two pictures with the knife edge at two different orientations by using equations derived by Wesemann et al. In natural eyes, the procedure has limitations because undetermined factors (not considered in the theory) affect size, shape, and intensity of the light crescent. A second possibility is to perform eccentric photorefraction separately in at least three different meridians. We have tested the power of the second possibility. The three critical parameters (sphere, cylinder, and axis) were calculated from Euler's law, which describes curvatures (or refractions) at any given angle. The procedure relied only on empirical calibration and not on a theoretical treatment of the optics. Therefore, it was not necessary to identify all factors that determine the path of light. The procedure compared favorably with subjective refractive (first population: students, age 26-30 years, N = 7 (14 eyes); correlations: sphere, r = 0.983; cylinder, r = 0.867; axis, r = 0.935) and with a Canon R-1 Autorefractor (second population: children, age 4-14 years, N = 48 (96 eyes); correlations: sphere, r = 0.955; cylinder, r = 0.600; axis, r = 0.846). Because it is fast, the technique may be suitable for screening in children. The refractions in the different meridians are performed in real time (25 to 30 Hz) and a single reading (the average from 4-6 refractions in each of the 6 meridians) is obtained in 1-2 s. It constitutes a major improvement to commercially available videorefractors which use measurements only in two meridians in conjunction with the formula by Wesemann et al., although it is still not precise enough to permit spectacle prescription.

  10. Láser in situ keratomileusis en la corrección de miopía y astigmatismo residual posqueratotomía radial en casos seleccionados Laser in situ keratomileusis to correct myopia and residual astigmatism after radial keratotomy in selected cases

    Directory of Open Access Journals (Sweden)

    Eneida Pérez Candelaria

    2010-01-01

    descriptive study was performed in 55 eyes from 31 patients with residual myopia and/or astigmatism after radial keratotomy, who were re-operated on using Laser in situ keratomileusis at Refractive Surgery Service of "Ramón Pando Ferrer" Cuban Institute of Ophthalmology from January to June 2007. Strict inclusion and exclusion criteria were applied to select the patients, on the basis of following variables: residual refractive errors in average spheral equivalent, visual acuity without correction and best visual acuity with correction before and after LASIK as well as the transoperative and postoperative complications. The average follow-up period were 12 ± 3 months. RESULTS: The spheral equivalent after LASIK was substantially reduced in the first day of the postoperative phase and kept stable in the last appointment with the specialist. The visual acuity without correction after LASIK was 1,0 (20/20 in 22 eyes (40% and > 0,5 (20/40 in 44 eyes (80 %. In eleven eyes (20%, the best corrected visual acuity improved by one line in the Snellen´s chart. The transoperative complication was found in one eye with central corneal flap perforation whereas the reported postoperative complications were detritus and hematic remains in the interphase in 2 eyes, fine foldings of the flap in one eye and epithelization of the interphase out of the visual axis also in one eye. CONCLUSIONS: The Laser in situ keratomileusis can be used successfully to correct myopia and astigmatism after radial keratotomy in duly selected cases.

  11. Aspheric spectacles for correcting presbyopia with myopia and astigmatism.

    Science.gov (United States)

    Zheng, Shaolin; Wang, Zhaoqi; Liu, Yongji; Li, Rui

    2012-10-10

    The aim of this paper is to propose a method for designing aspheric spectacles capable of realizing good optical performance at both far and near vision for presbyopia. We have experimentally measured wavefront aberrations and axial lengths for eight myopic eyes. In consideration of the field of view (FOV), the rotation of the eyeball, and a small amount of accommodation retained for presbyopia, we constructed individual eye models and optimized all the spectacle-eye systems for visible wavelengths by Zemax's simulation. Finally, we evaluated the image quality by the modulation transfer function (MTF) and visual acuity (VA) with different pupil sizes (2, 2.8, 4 mm). Results show that when the pupil size is 2 mm or 2.8 mm, the spectacles designed for the full FOV (0° and ±4° FOV) provide a strong ability to transfer low contrast at both far and near vision, and the VA for all reaches 0.8, and up to 1.1 for eyes NO. 1, NO. 5, NO. 6, and NO. 8 for the 0° FOV. As the pupil size increases to 4 mm, the VA for all comes to 0.6 for the full FOV, indicating that presbyopia is able to acquire a good visual resolution at both far and near vision by the designed aspheric spectacles. Furthermore, we verified the visual continuity of the spectacle-eye systems by studying intermediate vision, which demonstrates that the method used in our design is accurate and practicable.

  12. Cancellation of RF Coupler-Induced Emittance Due to Astigmatism

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, David H.; /SLAC

    2016-12-11

    It is well-known that the electron beam quality required for applications such as FEL’s and ultra-fast electron diffraction can be degraded by the asymmetric fields introduced by the RF couplers of superconducting linacs. This effect is especially troublesome in the injector where the low energy beam from the gun is captured into the first high gradient accelerator section. Unfortunately modifying the established cavity design is expensive and time consuming, especially considering that only one or two sections are needed for an injector. Instead, it is important to analyze the coupler fields to understand their characteristics and help find less costly solutions for their cancellation and mitigation. This paper finds the RF coupler-induced emittance for short bunches is mostly due to the transverse spatial sloping or tilt of the field, rather than the field’s time-dependence. It is shown that the distorting effects of the coupler can be canceled with a static (DC) quadrupole lens rotated about the z-axis.

  13. Femtosecond laser-assisted intrastromal corneal ring segment implantation for high astigmatism correction after penetrating keratoplasty.

    Science.gov (United States)

    Lisa, Carlos; García-Fernández, Miriam; Madrid-Costa, David; Torquetti, Leonardo; Merayo-Lloves, Jesús; Alfonso, José Fernando

    2013-11-01

    To assess the visual and refractive outcomes of femtosecond laser-assisted implantation of Ferrara-type intrastromal corneal ring segments (ICRS) in post-penetrating keratoplasty (PKP) eyes. Instituto Oftalmológico Fernández-Vega, Oviedo, Spain. Cohort study. Patients with previous PKP had ICRS implantation after femtosecond laser tunnel creation. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities and residual refractive errors were recorded before and 6 months after ICRS implantation. The power vector method was used to analyze refractive errors preoperatively and postoperatively. This study enrolled 32 eyes of 30 patients. The mean UDVA (Snellen decimal) changed from 0.16 ± 0.15 (SD) preoperatively to 0.43 ± 0.28 postoperatively (Pastigmatism components were significantly reduced after ICRS implantation (Pastigmatism correction in post-PKP eyes. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  14. Toric Intraocular Lenses in the Correction of Astigmatism During Cataract Surgery

    DEFF Research Database (Denmark)

    Kessel, Line; Andresen, Jens; Tendal, Britta

    2016-01-01

    TOPIC: We performed a systematic review and meta-analysis to evaluate the benefit and harms associated with implantation of toric intraocular lenses (IOLs) during cataract surgery. Outcomes were postoperative uncorrected distance visual acuity (UCDVA) and distance spectacle independence. Harms we...

  15. High-speed atomic force microscope based on an astigmatic detection system

    Science.gov (United States)

    Liao, H.-S.; Chen, Y.-H.; Ding, R.-F.; Huang, H.-F.; Wang, W.-M.; Hwu, E.-T.; Huang, K.-Y.; Chang, C.-S.; Hwang, I.-S.

    2014-10-01

    High-speed atomic force microscopy (HS-AFM) enables visualizing dynamic behaviors of biological molecules under physiological conditions at a temporal resolution of 1s or shorter. A small cantilever with a high resonance frequency is crucial in increasing the scan speed. However, detecting mechanical resonances of small cantilevers is technically challenging. In this study, we constructed an atomic force microscope using a digital versatile disc (DVD) pickup head to detect cantilever deflections. In addition, a flexure-guided scanner and a sinusoidal scan method were implemented. In this work, we imaged a grating sample in air by using a regular cantilever and a small cantilever with a resonance frequency of 5.5 MHz. Poor tracking was seen at the scan rate of 50 line/s when a cantilever for regular AFM imaging was used. Using a small cantilever at the scan rate of 100 line/s revealed no significant degradation in the topographic images. The results indicate that a smaller cantilever can achieve a higher scan rate and superior force sensitivity. This work shows the potential for using a DVD pickup head in future HS-AFM technology.

  16. Comparison of multifocal and monovision soft contact lens corrections in patients with low-astigmatic presbyopia.

    Science.gov (United States)

    Richdale, Kathryn; Mitchell, G Lynn; Zadnik, Karla

    2006-05-01

    The purpose of this study was to assess visual performance and patient satisfaction with two presbyopic soft contact lens modalities. A crossover study of 38 patients with presbyopia was conducted. Patients were randomized first into either multifocal (Bausch & Lomb SofLens Multifocal) or monovision (SofLens 59) for 1 month. Visual performance was measured with high- and low-contrast visual acuity at distance and near and near stereoacuity. Patients' satisfaction was measured by the National Eye Institute Refractive Error Quality of Life Instrument questionnaire and by recording the patient's final lens preference. Patients maintained at least 20/20 binocular vision with both multifocal (MF) and monovision (MV) contact lenses under high-contrast conditions at distance and near. Under low-contrast conditions, patients lost less than a line of vision from the best spectacle correction to either multifocal or monovision contact lens correction at distance (pMF = 0.001, pMV = 0.006). Under low-contrast conditions at near, multifocal wearers lost five to six letters and monovision wearers lost two letters of vision (pMF contact lenses (p = 0.002). On the NEI-RQL, patients reported worse clarity of vision (pMF = 0.01, pMV contact lens wear (pMF contact lenses, and 24% preferred monovision contact lenses (p = 0.001). The majority of our patients preferred multifocals to monovision, most likely because the Bausch & Lomb SofLens Multifocal provides excellent visual acuity without compromising stereoacuity to the same degree as monovision.

  17. The ABCD matrix for parabolic reflectors and its application to astigmatism free four-mirror cavities

    Science.gov (United States)

    Dupraz, K.; Cassou, K.; Martens, A.; Zomer, F.

    2015-10-01

    The ABCD matrix for parabolic reflectors is derived for any incident angles. It is used in numerical studies of four-mirror cavities composed of two flat and two parabolic mirrors. Constraints related to laser beam injection efficiency, optical stability, cavity-mode, beam-waist size and high stacking power are satisfied. A dedicated alignment procedure leading to stigmatic cavity-modes is employed to overcome issues related to the optical alignment of parabolic reflectors.

  18. Measuring the 3D motion of particles in microchannel acoustophoresis using astigmatism particle tracking velocimetry

    DEFF Research Database (Denmark)

    Augustsson, P.; Barnkob, Rune; Bruus, Henrik

    2012-01-01

    are examined in three dimensions. We have quantified the velocity of particles driven by the primary acoustic radiation force and acoustic streaming, respectively, using 0.5-μm and 5-μm particles. Increased ultrasound frequency and lowered viscosity of the medium reduced the influence of acoustic streaming...

  19. Management of Extreme Ametropia after Penetrating Keratoplasty: A Series of Surgical Procedures for High Myopia and Astigmatism

    Directory of Open Access Journals (Sweden)

    Jorge E. Valdez-Garcia

    2014-08-01

    Full Text Available A series of surgical interventions - relaxing corneal incisions, intraocular lens, and intrastromal rings - were used to correct a case of extreme ametropia in a thin cornea after a penetrating keratoplasty in an 18-year-old patient who presented with a -10.25 -8.50 × 120 preoperative refraction and 20/200 best-corrected visual acuity (BCVA. After a series of surgical procedures, the patient's BCVA in his left eye improved to 20/30 with +0.50 -1.00 × 170, the slit lamp examination showed no significant findings, and the patient's visual complaints disappeared. At the 1-year follow-up, the BCVA was 20/25, without visual complaints. The process of individualizing the surgical procedure in the present case was employed in an outcome-based approach, that is, the next surgical procedure was defined after the surgery and postoperative evaluation. The patient did not present complications during the follow-up period of 2.5 years.

  20. Laser-assisted subepithelial keratectomy and photorefractive keratectomy for post-penetrating keratoplasty myopia and astigmatism in adults.

    Science.gov (United States)

    Huang, Paul Y C; Huang, Peter T; Astle, William F; Ingram, April D; Hèbert, Ania; Huang, John; Ruddell, Stacy

    2011-02-01

    To evaluate whether laser-assisted subepithelial keratectomy (LASEK) and photorefractive keratectomy (PRK) achieve effective targeted correction and the extent of post-treatment corneal haze after corneal transplantation. Nonhospital surgical facility, Calgary, Alberta, Canada. Evidence-based manuscript. This study evaluated visual acuity, refractive error correction, and potential complications after LASEK or PRK to eliminate refractive error differences after penetrating keratoplasty in adults. A Nidek EC-5000 or Technolas 217 excimer laser was used in all treatments. At last follow-up (mean 20.50 months post laser), the mean spherical equivalent (SE) decreased from -2.71 diopters (D) ± 4.17 (SD) to -0.54 ± 3.28 D in the LASEK group and from -4.87 ± 3.90 D to -1.82 ± 3.34 D in the PRK group. The mean preoperative uncorrected distance visual acuity (UDVA) was 1.63 ± 0.53 and 1.45 ± 0.64, respectively, and the mean postoperative UDVA, 0.83 ± 0.54 and 0.90 ± 0.55, respectively. The improvement in SE and UDVA was statistically significant in both groups (P < .01). The mean haze (0 to 3 scale) at the last follow-up was 0.46 ± 0.708 in the LASEK group and 0.58 ± 0.776 in the PRK group. The UDVA improved and refractive errors were effectively reduced after LASEK or PRK in eyes with previous PKP. There was no significant difference in the change in SE, UDVA, or corrected distance visual acuity between LASEK and PRK. Some patients had evidence of corneal haze, although the difference between the groups was not significant. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  1. Corneal astigmatism correction with scleral flaps in trans-scleral suture-fixed posterior chamber lens implantation:a preliminary clinical observation

    National Research Council Canada - National Science Library

    Dwight Xuan

    2011-01-01

    ... suture.The incision for IOL implantation was made 1mm posterior to limbus along the steepest meridian of cornea,while scleral flaps to bury the knots of trans-scleral suture were made along the flattest...

  2. Astigmatic mites from nests of birds of prey in the U.S.A. : IV. Description of the life-cycle of Acotyledon paradoxa Oudemans, 1903

    NARCIS (Netherlands)

    Fain, A.; Philips, J.R.

    1978-01-01

    INTRODUCTION In this paper we describe for the first time the life-cycle of Acotyledon paradoxα Oudemans, 1903. This species was known, so far, only from the hypopial stage and a protonymph. The discovery of the adults allows us to precise the systematic position of the genus Acotyledon and to throw

  3. Refractive errors in school children in Onitsha, Nigeria | Nwosu ...

    African Journals Online (AJOL)

    Spherical errors were namely, hyperopia 23 (7.5%); myopia 47 (15.4%). Astigmatism occurred in 231 (75.5%) namely hyperopic astigmatism 72 (31.2%); myopic astigmatism 159 (68.8%). Anisometropia was present in 80 (26.1%) children, 16 of whom did not improve with refraction. Generally older children (12 – 17 years) ...

  4. Astigmatismo posquirúrgico en la facoemulsificación según el lugar de la incisión Postsurgical astigmatism in phacoemulsification according to the surgical site

    OpenAIRE

    Juan Raúl Hernández Silva; Meisy Ramos López; Luis Curbelo Cunill; Gilberto Fernández Vásquez; Marcelino Rio Torres; Yanele Ruiz Rodríguez

    2012-01-01

    Objetivo: Determinar el astigmatismo inducido por la técnica de facoemulsificación según el lugar de la incisión en los pacientes operados de catarata en el Instituto Cubano de Oftalmología "Ramón Pando Ferrer" de enero a diciembre de 2010. Métodos: Se realizó un estudio descriptivo, longitudinal y retrospectivo en 2 510 pacientes operados de catarata mediante la técnica de faco chop por diferentes zonas de abordaje de la incisión principal (superior, oblicua, temporal) y extracción extracaps...

  5. Posterior Corneal Characteristics of Cataract Patients with High Myopia.

    Science.gov (United States)

    Jing, Qinghe; Tang, Yating; Qian, Dongjin; Lu, Yi; Jiang, Yongxiang

    2016-01-01

    To evaluate the characteristics of the posterior corneal surface in patients with high myopia before cataract surgery. We performed a cross-sectional study at the Eye and ENT Hospital of Fudan University, Shanghai, China. Corneal astigmatism and axial length were measured with a rotating Scheimpflug camera (Pentacam) and partial coherence interferometry (IOLMaster) in a high-myopia study group of 167 eyes (axial length ≥ 26 mm) and a control group of 150 eyes (axial length > 20 mm and myopia group than in the control group. There was no significant difference in posterior corneal astigmatism between the high-myopia study group and the control group. In the study group, the mean posterior corneal astigmatism (range 0 - -0.9 diopters) was -0.29 diopters (D) ± 0.17 standard deviations (SD). The steep corneal meridian was aligned vertically (60°-120°) in 87.43% of eyes for the posterior corneal surface, and did not change with increasing age. There was a significant correlation (r = 0.235, p = 0.002) between posterior corneal astigmatism and anterior corneal astigmatism, especially when the anterior corneal surface showed with-the-rule (WTR) astigmatism (r = 0.452, p = 0.000). There was a weak negative correlation between posterior corneal astigmatism and age (r = -0.15, p = 0.053) in the high-myopia group. Compared with total corneal astigmatism values, the anterior corneal measurements alone overestimated WTR astigmatism by a mean of 0.27 ± 0.18 D in 68.75% of eyes, underestimated against-the-rule (ATR) astigmatism by a mean of 0.41 ± 0.28 D in 88.89% of eyes, and underestimated oblique astigmatism by a mean of 0.24 ± 0.13 D in 63.64% of eyes. Posterior corneal astigmatism decreased with age and remained as ATR astigmatism in most cases of high myopia. There was a significant correlation between posterior corneal astigmatism and anterior corneal astigmatism when anterior corneal astigmatism was WTR. If posterior corneal astigmatism is not accounted for when

  6. The use of Wavelight® Contoura to create a uniform cornea: the LYRA protocol. Part 3: the results of 50 treated eyes

    Directory of Open Access Journals (Sweden)

    Motwani M

    2017-05-01

    Full Text Available Manoj Motwani Motwani LASIK Institute, San Diego, CA, USA Purpose: To demonstrate how using the Wavelight Contoura measured astigmatism and axis eliminates corneal astigmatism and creates uniformly shaped corneas. Patients and methods: A retrospective analysis was conducted of the first 50 eyes to have bilateral full WaveLight® Contoura LASIK correction of measured astigmatism and axis (vs conventional manifest refraction, using the Layer Yolked Reduction of Astigmatism Protocol in all cases. All patients had astigmatism corrected, and had at least 1 week of follow-up. Accuracy to desired refractive goal was assessed by postoperative refraction, aberration reduction via calculation of polynomials, and postoperative visions were analyzed as a secondary goal. Results: The average difference of astigmatic power from manifest to measured was 0.5462D (with a range of 0–1.69D, and the average difference of axis was 14.94° (with a range of 0°–89°. Forty-seven of 50 eyes had a goal of plano, 3 had a monovision goal. Astigmatism was fully eliminated from all but 2 eyes, and 1 eye had regression with astigmatism. Of the eyes with plano as the goal, 80.85% were 20/15 or better, and 100% were 20/20 or better. Polynomial analysis postoperatively showed that at 6.5 mm, the average C3 was reduced by 86.5% and the average C5 by 85.14%. Conclusions: Using WaveLight® Contoura measured astigmatism and axis removes higher order aberrations and allows for the creation of a more uniform cornea with accurate removal of astigmatism, and reduction of aberration polynomials. WaveLight® Contoura successfully links the refractive correction layer and aberration repair layer using the Layer Yolked Reduction of Astigmatism Protocol to demonstrate how aberration removal can affect refractive correction. Keywords: WaveLight Contoura, topographic guided ablation, LASIK, PRK, uniform cornea, Contoura with LYRA Protocol, measured astigmatism

  7. New Refractive Surgery Procedures and Their Implications for Aviation Safety

    National Research Council Canada - National Science Library

    Nakagawara, Van B; Wood, Kathryn J; Montgomery, Ron W

    2006-01-01

    ...., myopia, hyperopia, astigmatism) with corrective surgery. Prior Federal Aviation Administration research studies have shown that the number of civil airmen with refractive surgery continues to increase...

  8. The U.S. Air Force Photorefractive Keratectomy (PRK) Study: Evaluation of Residual Refractive Error and High- and Low-Contrast Visual Acuity

    Science.gov (United States)

    2006-07-01

    undercorrection, overcorrection, induced astigmatism, and anisometropia . Low to moderate residual refractive error after refractive surgery may be...19 7 Incidence of Anisometropia in PRK-Treated Subjects at Baseline and After Surgery...overcorrection, induced astigmatism, and anisometropia . The primary concern for distance visual acuity was undercorrection and/or regression over time similar

  9. Visual Outcomes after Phacoemulsification with AcrySof Toric ...

    African Journals Online (AJOL)

    Introduction: To study the visual outcome of AcrySof toric intraocular lens (IOL) implantation in patients having cataract associated with astigmatism. Materials and Methods: In this prospective interventional case series, 30 eyes of 28 patients with preoperative astigmatism of 1.5–4.5D cylinder underwent phacoemulsification ...

  10. PEDIATRIC OPHTHALMLOGY AND STRABISMUS

    African Journals Online (AJOL)

    The most common diagnosis was simple myopic astigmatism (41.1%), then myopia, anisometropia, and compound myopic astigmatism with 21.7%, 10.6%, and 8.9%, respectively [Tables 1 and 2]. Conclusion: A good percentage of these children (females than males) have significant error which was correctable by glasses.

  11. Contact lenses following keratoplasty.

    Science.gov (United States)

    Beekhuis, W H; van Rij, G; Eggink, F A; Vreugdenhil, W; Schoevaart, C E

    1991-01-01

    Bandage contact lenses can be used following keratoplasty to protect the ocular surface and promote epithelial healing. Rigid gas permeable contact lenses are indicated to correct irregular astigmatism and anisometropia. The Rotterdam Eye Hospital fit 77 keratoplasty patients with contact lenses following their surgery. The methods of fitting contact lenses over the irregular or highly astigmatic surface of a graft are discussed.

  12. Small Incision Lenticule Extraction (SMILE) vs. Femtosecond Laser in Situ Keratomileusis (FS-LASIK) for treatment of myopia

    DEFF Research Database (Denmark)

    Hansen, Rasmus Søgaard; Justesen, Birgitte; Lyhne, Niels

    treatments were performed at the Department of Ophthalmology, Odense University Hospital from April 2011 to December 2013. Inclusion criteria: CDVA ≤ 0.10 (logMAR) before surgery and no other ocular conditions than myopia with or without astigmatism of maximum 3 D. Exclusion criteria: Eyes having undergone...... of astigmatism, and results were overall comparable 3 months after surgery. Financial disclosures: None....

  13. Refractive Error among Strabismic Children in Ilorin, Nigeria ...

    African Journals Online (AJOL)

    Hypermetropia was the commonest refractive error among the children (50%) followed by astigmatism (30%) and myopia (20%). There was more astigmatism among esotropic children (66.7%) compared to exotropic children (33.3%). Majority of the hypermetropia (85%) was associated with esotropia while most of the ...

  14. Visual Outcomes after Phacoemulsification with AcrySof Toric ...

    African Journals Online (AJOL)

    2016-12-13

    Dec 13, 2016 ... Introduction: To study the visual outcome of AcrySof toric intraocular lens (IOL) implantation in patients having cataract associated with astigmatism. Materials and Methods: In this prospective interventional case series, 30 eyes of 28 patients with preoperative astigmatism of. 1.5–4.5 D cylinder underwent ...

  15. Investigation of the 2-m telescope optics and seeing at the Terskol Peak Observatory

    Science.gov (United States)

    Butenko, G. Z.; Kuznetsov, V. I.; Snezhko, L. I.; Andruk, V. M.; Parusimov, V. G.; Sergeev, A. V.; Ivanov, Yu. S.

    2000-09-01

    We present the Hartmann images to attestate the Cassegrain focus optics of the 2-m telescope of the Peak Terskol Observatory of the International Center for Astronomical and Medico-Ecological Research of the NASU/RAS. The Cassegrain focus optics is a classical Ritchey-Chretien system with compensated coma and spherical aberration. The astigmatism corrector compensates for the system field astigmatism. Star images formed by the system with the astigmatism corrector are characterized by d0.8=1.''3, which does not meet the present-day requirements. The constant coma followed by the spherical aberration are dominating. The astigmatism is the least distortion of the image. Eliminating the Zeidel aberrations gives d0.8=0.''7, which coincides with manufacturer attestation. An additional adjustment should be made to achieve this image quality. Local wavefront errors including triangular astigmatism are small, which testifies that the unloading and fastening of the mirrors are of a high quality.

  16. Using corneal topography design personalized cataract surgery programs

    Directory of Open Access Journals (Sweden)

    Jin-Ou Huang

    2014-08-01

    Full Text Available AIM:To investigate how to design personalized cataract surgery programs to achieve surgical correction of preoperative corneal astigmatism with surgical astigmatism under the guidance of corneal topography, improve postoperative visual quality and reduce the cost of treatment. METHODS: Totally 202 cases(226 eyescataract patients were divided into randomized treatment group and individualized treatment group. According to the method and location of the incision, randomized treatment group were divided into 8 groups. Surgical astigmatism after different incision were calculated with the use of preoperative and postoperative corneal astigmatism through vector analysis method. Individualized treatment groups were designed personably for surgical method with reference of every surgically induced astigmatism, the surgical method chooses the type of surgical incision based on close link between preoperative corneal astigmatism and surgically induced astigmatism, and the incision was located in the steep meridian. The postoperative corneal astigmatism of individualized treatment group was observed. RESULTS: Postoperative corneal astigmatism of individualized treatment group were lower than that of 3.0mm clear corneal tunnel incision in the randomized treatment group, there were statistically significance difference, while with 3.0mm sclera tunnel incision group there were no statistically significance difference. After 55.8% of patients with the use of individualized surgical plan could undergo the operation of extracapsular cataract extraction with relatively low cost and rigid intraocular lens implantation, the per capita cost of treatment could be reduced. CONCLUSION: Personalized cataract surgery programs are designed to achieve surgical correction of preoperative corneal astigmatism under the use of corneal topography, improve postoperative visual quality and reduce the cost of treatment.

  17. Refractive error may influence mesopic pupil size.

    Science.gov (United States)

    Cakmak, Hasan Basri; Cagil, Nurullah; Simavli, Huseyin; Duzen, Betul; Simsek, Saban

    2010-02-01

    To identify factors which affect mesopic pupil diameter in refractive surgery patients. This retrospective study was performed at the 1st Ophthalmology Clinic in Ankara Ataturk Training and Research Hospital, Ankara, Turkey. Medical records of 412 refractive surgery candidates who applied between 2006 and 2008 were reviewed. Detailed ophthalmological examination data were obtained from medical records. Pupil size measurements were performed with a COAS Ocular Wavefront analyzer in mesopic conditions. Relationship between mesopic pupil diameter and age, sex, spherical refractive error (D), magnitude of astigmatism (D), type of astigmatism, spherical equivalent, and average keratometry were analyzed by means of univariate and multivariate regression analyses. Mean mesopic pupil diameter was 6.19 +/- 0.88 mm. Mean pupil diameter (mean +/- standard deviation) was 5.70 +/- 1.01 in hypermetropia, 6.04 +/- 0.79 mm in mixed astigmatism, and 6.33 +/- 0.82 mm in myopia. The difference in mean mesopic pupil diameters between myopes and hypermetropes was statistically significant (p = 0.001). However, differences with regard to mean pupil diameters between myopes and mixed astigmatism (p = 0.660) and between hypermetropes and mixed astigmatism (p = 0.109) were not significant. Mean pupil diameter was 6.00 +/- 0.99 mm in against the rule astigmatism, 5.96 +/- 0.84 mm in oblique astigmatism, and 6.27 +/- 0.84 mm in with the rule astigmatism. Mean mesopic pupil diameter in with the rule astigmatism group was higher than oblique astigmatism group. Spherical refractive error (r = -0.213, p = 0.001), cylindrical refractive error (0.197, p = 0.001), and age (r = -0.341, p = 0.001) showed correlation with pupil diameter. This study showed that age and magnitude of both spherical and cylindrical refractive error are the most determinative factors on mesopic pupil size.

  18. Fourier analysis of videokeratography data: Clinical usefulness in grade I and subclinical keratoconus.

    Science.gov (United States)

    Sideroudi, Haris; Labiris, Georgios; Georgatzoglou, Kimon; Ditzel, Fienke; Siganos, Charalambos; Kozobolis, Vassilios

    2016-05-01

    To evaluate the contribution of Fourier analysis of videokeratographic data in the diagnosis of subclinical keratoconus and keratoconus. Eye Institute of Thrace, Democritus University, Alexandroupolis, Greece. Observational case series. The following Pentacam-derived parameters, resulting from Fourier decomposition of keratometric data, were evaluated for their diagnostic capacity using receiver operating curves: spherical component and eccentricity, maximum decentration, regular astigmatism in the center and in the periphery, mean astigmatism, irregularities, regular astigmatism in the center plus the irregularities, and total astigmatism. Logistic regression was performed to identify a combined diagnostic model. The study comprised 80 keratoconus eyes, 55 eyes diagnosed with subclinical keratoconus, and 50 normal eyes. Significant differences were detected in spherical eccentricity, maximum decentration, irregularities, regular astigmatism in the center and in the periphery, regular astigmatism in the center plus the irregularities, mean astigmatism, and total astigmatism parameters between the groups. Almost all parameters had high diagnostic ability in both study groups (area under the curve >90%). Among individual parameters, those with the highest predictive accuracy were the regular astigmatism in the center plus the irregularities (subclinical keratoconus 97.6%, keratoconus 98.8%) and the maximum decentration (subclinical keratoconus 91.4%, keratoconus 98.5%). Sufficient predictive accuracy (subclinical keratoconus 99.4, keratoconus 100%) was identified in a diagnostic model that combined the regular astigmatism in the center plus the irregularities and the maximum decentration. Fourier decomposition of keratometric data provided parameters with high accuracy in differentiating corneas with subclinical keratoconus from normal corneas and should be included to allow prompt diagnosis of keratoconus. None of the authors has a financial or proprietary interest

  19. Necessity of correcting short distance refractive error in non-presbyopia patients

    Directory of Open Access Journals (Sweden)

    Wen-Lan Liu

    2014-03-01

    Full Text Available AIM: To find out the necessity and the appropriate method of correcting short distance refractive error in non-presbyopia patients by analyzing the relation between astigmatic refractive error and fixation distance.METHODS: In this prospective clinical study, 166 right eyes with myopic astigmatism were selected by sequential processing to measure at distance of 5m, 40cm and 20cm. The distance corrected near vision acuity(NCNVAand accommodative astigmatism corrected near vision acuity(ACNVAwere measured with distance-corrected glasses and near-corrected glasses, respectively, using near vision chart. The astigmatism at near were measured under monocular condition with cross-cylinder lenses, with the tested eye looking straight ahead at the line of its best corrected vision acuity in near vision chart. The degree and axis of astigmatism between two distance of the three, DCNVA and ACNVA were compared by paired t test respectively if the data are normal distribution, if not, compared by Wilcoxon matched-pairs signed-ranks test. RESULTS: The degree of astigmatism with accommodation was increased significantly as follow order: fixating at 20cm, 40cm and distance. \\〖(40cm-5m: Z=-5.316, PZ=-5.672, PZ=-2.463; P40cm,(0.78DC±0.43D>5m, 0.63DC±0.47D\\〗; The near vision acuity when fixing at 40cm and 20cm were both increased significantly when accommodative astigmatism corrected(Z=-5.741, PZ=-6.848, PCONCLUSION: The degree of astigmatism has a tendency of increasing when fixating at near, and astigmatism with the rule will be followed by the axis, while this change is random and personalized, asthenopia is more likely to appear at the distance of maxium astigmatism change, so correct the refractive error at near may be a appropriate method to treat asthenopia.

  20. Clinical analysis of outpatients with ametropia in Hebeisheng Eye Hospital

    Directory of Open Access Journals (Sweden)

    Xiao Chen

    2017-11-01

    Full Text Available AIM: To perform a clinical analysis of 1 500 cases of outpatients with ametropia in Hebeisheng Eye Hospital, to provide a theoretical basis for diagnosis, treatment, and prevention of patients with ametropia.METHODS: Totally 1 500 cases(2 840 eyesof outpatient with ametropia were chosen as the research objects in Hebeisheng Eye Hospital from June 2013 to July 2014. All cases were treated with TOPCON RM-8800 computer optometry instrument for objective optometry, and used TOPCON phoropter for subjective optometry. The combination of the two instruments was taken to determine the diopter later. Diopter and axial distribution of the myopic astigmatism and hyperopic astigmatism were observed, age of astigmatic patient, distribution of astigmatism axis were observed as well. Meanwhile, a total of 150 cases were chosen randomly to measure their corneal curvature, anterior chamber depth, axial length and other static refractive index. All indexes were compared with those of the normal people subsequently, such as amplitude of accommodation, negative relative accommodation, positive relative accommodation, sensitivity of accommodation and other dynamic refractive index. RESULTS: Ametropia types of all patients were mainly simple myopia, simple myopia astigmatism, compound myopic astigmatism, simple hypermetropia, simple hyperopia astigmatism, compound hyperopic astigmatism and mixed astigmatism, the proportion were 38.99%, 3.27%, 23.94%, 4.68%, 1.34%, 13.52%, 15.25% respectively. There were 773 eyes with myopia astigmatism. The proportion of people with a myopia astigmatism diopter of above -0.25 to -0.50, -0.75 to -1.00, -1.25 to -1.50, above -1.75 were 31.05%, 38.55%, 16.56%, 13.84%. There were 421 eyes with hyperopia astigmatism, the proportion of people with hyperopia astigmatism diopter of 0.25-0.50, 0.75-1.00, 1.25- 1.50, >1.75 were 26.60%, 24.94%, 16.63%, 31.83%. Static refractive index of 150 patients(300 eyesshowed that corneal curvature was(41

  1. Higher-order aberration corrector for an image-forming system in a transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Sawada, H., E-mail: hsawada@jeol.co.jp [CREST, Japan Science and Technology Agency, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan); JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo (Japan); Sasaki, T. [CREST, Japan Science and Technology Agency, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan); JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo (Japan); Hosokawa, F.; Yuasa, S.; Terao, M.; Kawazoe, M.; Nakamichi, T. [JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo (Japan); Kaneyama, T. [CREST, Japan Science and Technology Agency, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan); JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo (Japan); Kondo, Y. [CREST, Japan Science and Technology Agency, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan); Kimoto, K. [CREST, Japan Science and Technology Agency, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan); National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Suenaga, K. [CREST, Japan Science and Technology Agency, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan); Research Center for Advanced Carbon Materials, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565 (Japan)

    2010-07-15

    We developed a new electron optical system with three dodecapoles to compensate for spherical aberration and six-fold astigmatism, which generally remains in a two-hexapole type corrector. In this study, we applied the corrector for image-forming system in transmission electron microscope. Compensation for higher-order aberration was demonstrated through a diffractogram tableau using a triple three-fold astigmatism field system, which was then compared with a double hexapole field system. Using this electron optical system, six-fold astigmatism was measured to be less than 0.1 mm at an acceleration voltage of 60 kV, showing that the system successfully compensated for six-fold astigmatism.

  2. Ptosis - infants and children

    Science.gov (United States)

    Blepharoptosis - children; Congenital ptosis; Eyelid drooping - children; Eyelid drooping - amblyopia; Eyelid drooping - astigmatism ... Ptosis in infants and children is often due to a problem with the muscle that raises the eyelid. A nerve problem in the eyelid can ...

  3. Functional and refractive results after one month of AcrySof toric intraocular lens implantation

    Directory of Open Access Journals (Sweden)

    Francisco Alba-Bueno

    2011-04-01

    Conclusions: The implantation of SN60T toric IOL in patients with CA higher than 0.75 D is a safe, predictable and effective way of reducing refractive astigmatism in patients undergoing cataract surgery.

  4. Anatomical and functional graft survival, 10 years after epikeratoplasty in keratoconus

    National Research Council Canada - National Science Library

    Panda, Anita; Gupta, Anoop K; Sharma, Namrata; Nindrakrishna, Sasikala; Vajpayee, Rasik

    2013-01-01

    To report outcomes of epikeratoplasty in keratoconus (KC), utilizing manually-prepared plano donor lenticules in terms of flattening of the cone, reduction in astigmatism and improvement in the visual acuity...

  5. [Toric IOLs after cataract surgery and refractive lens exchange].

    Science.gov (United States)

    Auffarth, G U; Rabsilber, T M

    2007-12-01

    Patients with astigmatism (e.g. regular or keratoplasty-induced astigmatism) who undergo cataract surgery or refractive lens exchange with a standard monofocal IOL are often disappointed. Toric IOLs (T-IOLs) are, therefore, an excellent alternative for this condition. T-IOLs are now available from companies such as Alcon, Acri, Tec, Humanoptics, Wavelight, Rayner and Staar. Apart from Alcon and Staar who only produce T-IOLs with a fixed torus, all these produce customised lenses. The calculations needed for production of the T-IOLs are generally done by the companies and are based on the corneal astigmatism. T-IOLs have shown good rotational stability and good functional results. Corneal astigmatism can still be measured postoperatively, as it is corrected inside the eye. The referring ophthalmologist should exercise discretion when prescribing spectacles after surgery of this kind.

  6. Standard eye exam

    Science.gov (United States)

    ... the eye ( glaucoma ) using a method called tonometry Color blindness is tested using cards with colored dots that ... Astigmatism (abnormally curved cornea) Blocked tear duct Cataracts Color blindness Corneal abrasion (or dystrophy) Corneal ulcers and infections ...

  7. [Correction of refractive errors in patients with strabismus. Part II. Clinical aspects of refraction--spectacle and contact lens correction].

    Science.gov (United States)

    Tokarz-Sawińska, Ewa

    2012-01-01

    In Part II the clinical aspects of refractive errors such as hyperopia, myopia, astigmatism, anisometropia, aphakia and unilateral pseudophakia have been described along with strabismus and prism and spectacle correction allowing additionally proper visual alignment.

  8. 78 FR 13350 - Ophthalmic Devices Panel of the Medical Devices Advisory Committee; Notice of Meeting

    Science.gov (United States)

    2013-02-27

    ... eye for visual correction of aphakia and postoperative refractive astigmatism secondary to removal of... spectacles. FDA intends to make background material available to the public no later than 2 business days...

  9. 75 FR 9478 - Qualification of Drivers; Exemption Applications; Vision

    Science.gov (United States)

    2010-03-02

    ..., retinal detachment, macular scarring, optic atrophy, myopic astigmatism, and loss of vision due to trauma... either born with their vision impairments or have had them since childhood. The 14 individuals who...

  10. Reversible Femtosecond Laser-Assisted Myopia Correction: A Non-Human Primate Study of Lenticule Re-Implantation after Refractive Lenticule Extraction: e67058

    National Research Council Canada - National Science Library

    Andri K Riau; Romesh I Angunawela; Shyam S Chaurasia; Wing S Lee; Donald T Tan; Jodhbir S Mehta

    2013-01-01

      LASIK (laser-assisted in situ keratomileusis) is a common laser refractive procedure for myopia and astigmatism, involving permanent removal of anterior corneal stromal tissue by excimer ablation beneath a hinged flap...

  11. Reversible femtosecond laser-assisted myopia correction: a non-human primate study of lenticule re-implantation after refractive lenticule extraction

    National Research Council Canada - National Science Library

    Riau, Andri K; Angunawela, Romesh I; Chaurasia, Shyam S; Lee, Wing S; Tan, Donald T; Mehta, Jodhbir S

    2013-01-01

    LASIK (laser-assisted in situ keratomileusis) is a common laser refractive procedure for myopia and astigmatism, involving permanent removal of anterior corneal stromal tissue by excimer ablation beneath a hinged flap...

  12. Disease: H00690 [KEGG MEDICUS

    Lifescience Database Archive (English)

    Full Text Available (AIED) is an X-linked form of ocular hypopigmentation. Affected males demonstrate nystagmus, decreased visu...al acuity, myopia, astigmatism, achromatopsia, and fundus hypopigmentation. Eye disease CACNA1F [HSA:778] [K

  13. National Ignition Facility Beamline Pupil Relay Plane Location and Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Korniski, R J; Lawson, J K

    2002-01-29

    Axial astigmatism can be introduced into the nominal design of an optical system by tilted and tilted-wedged plates. The pupil images in the National Ignition Facility experience many such components. Some ramifications will be explored.

  14. Can the red-green duochrome test be used prior to correcting the refractive cylinder component?

    National Research Council Canada - National Science Library

    Gantz, Liat; Schrader, Shlomo; Ruben, Ruthie; Zivotofsky, Ari Z

    2015-01-01

    .... The duochrome red-green test is a standard tool for verification of the final refraction. Traditionally, it is recommended for use both prior to and subsequent to determining the cylindrical or astigmatic component of the refraction...

  15. Can the Red-Green Duochrome Test Be Used Prior to Correcting the Refractive Cylinder Component?: e0118874

    National Research Council Canada - National Science Library

    Liat Gantz; Shlomo Schrader; Ruthie Ruben; Ari Z Zivotofsky

    2015-01-01

    .... The duochrome red-green test is a standard tool for verification of the final refraction. Traditionally, it is recommended for use both prior to and subsequent to determining the cylindrical or astigmatic component of the refraction...

  16. Contact Lens Visual Rehabilitation in Keratoconus and Corneal Keratoplasty

    Directory of Open Access Journals (Sweden)

    Yelda Ozkurt

    2012-01-01

    Full Text Available Keratoconus is the most common corneal distrophy. It’s a noninflammatory progressive thinning process that leads to conical ectasia of the cornea, causing high myopia and astigmatism. Many treatment choices include spectacle correction and contact lens wear, collagen cross linking, intracorneal ring segments implantation and finally keratoplasty. Contact lenses are commonly used to reduce astigmatism and increase vision. There are various types of lenses are available. We reviewed soft contact lenses, rigid gas permeable contact lenses, piggyback contact lenses, hybrid contact lenses and scleral-semiscleral contact lenses in keratoconus management. The surgical option is keratoplasty, but even after sutur removal, high astigmatism may stil exists. Therefore, contact lens is an adequate treatment option to correct astigmatism after keratoplasty.

  17. Contact lens visual rehabilitation in keratoconus and corneal keratoplasty.

    Science.gov (United States)

    Ozkurt, Yelda; Atakan, Mehmet; Gencaga, Tugba; Akkaya, Sezen

    2012-01-01

    Keratoconus is the most common corneal distrophy. It's a noninflammatory progressive thinning process that leads to conical ectasia of the cornea, causing high myopia and astigmatism. Many treatment choices include spectacle correction and contact lens wear, collagen cross linking, intracorneal ring segments implantation and finally keratoplasty. Contact lenses are commonly used to reduce astigmatism and increase vision. There are various types of lenses are available. We reviewed soft contact lenses, rigid gas permeable contact lenses, piggyback contact lenses, hybrid contact lenses and scleral-semiscleral contact lenses in keratoconus management. The surgical option is keratoplasty, but even after sutur removal, high astigmatism may stil exists. Therefore, contact lens is an adequate treatment option to correct astigmatism after keratoplasty.

  18. A method for the prescription of inexpensive spectacles by non-specialist healthcare workers: S-Glasses.

    Science.gov (United States)

    Treacy, M P; Treacy, M G; Dimitrov, B D; Seager, F E; Stamp, M A; Murphy, C C

    2013-04-01

    Globally, 153 million people are visually impaired from uncorrected refractive error. The aim of this research was to verify a method whereby autorefractors could be used by non-specialist health-workers to prescribe spectacles, which used a small stock of preformed lenses that fit frames with standardised apertures. These spectacles were named S-Glasses (Smart Glasses). This prospective, single-cohort exploratory study enrolled 53 patients with 94 eligible eyes having uncorrected vision of 6/18 or worse. Eyes with best-corrected vision worse than 6/12 were excluded. An autorefractor was used to obtain refractions, which were adjusted so that eyes with astigmatism less than 2.00 dioptres (D) received spherical equivalent lenses, and eyes with more astigmatism received toric lenses with a 2.50 D cylindrical element set at one of four meridians. The primary outcome was to compare S-Glasses vision with the WHO definition of visual impairment (6/18). Where astigmatism was 2.00 D or greater, comparison with spherical equivalent was made. Mixed-model analysis with repeated effect was used to account for possible correlation between the vision of fellow eyes of the same individual. S-Glasses corrected 100% of eyes with astigmatism less than 3.00 D and 69% of eyes with astigmatism of 3.00 D or greater. Spherical equivalent lenses corrected 25% of eyes with astigmatism of 2.00-2.99 D and 11% with astigmatism of at least 3.00 D. S-Glasses could be beneficial to resource-poor populations without trained refractionists. This novel approach, using approximate toric lenses, results in superior vision for astigmatic patients compared with the practice of providing spherical equivalent alone.

  19. The effect of anisometropia on binocular visual function.

    OpenAIRE

    Dadeya S; Kamlesh; Shibal F

    2001-01-01

    PURPOSE: To investigate the effects of anisometropia on binocular vision. METHODS: One to three dioptres of unilateral hyperopia, myopia or astigmatism was induced in 30 normal adults. The effect on binocularity was assessed with the Worth-four dot test, Titmus stereo test and Bagolini′s lenses. RESULTS: Binocular vision deteriorated with increasing anisometropia. Spherical anisometropia was more deleterious than astigmatic anisometropia. CONCLUSION: In addition to amblyopia, the poten...

  20. Small Incision Lenticule Extraction (SMILE) vs. Femtosecond Laser in Situ Keratomileusis (FS-LASIK) for treatment of myopia

    DEFF Research Database (Denmark)

    Hansen, Rasmus Søgaard; Lyhne, Niels; Justesen, Birgitte

    of myopia. All treatments were performed at the Department of Ophthalmology, Odense University Hospital from April 2011 to December 2013. Inclusion criteria: CDVA ≤ 0.10 (logMAR) before surgery and no other ocular conditions than myopia with or without astigmatism of maximum 3 D. Exclusion criteria: Eyes...... degrees of myopia and low degrees of astigmatism, and results were overall comparable 3 months after surgery. Financial disclosures: None....

  1. Cost analysis of a mini-facet heliostat

    Science.gov (United States)

    Hall, Colin; Pratt, Rodney; Farrant, David; Corsi, Clotilde; Pye, John; Coventry, Joe

    2017-06-01

    A significant problem with conventional heliostats is off-axis astigmatism, which increases the spot size at the central receiver, limiting the temperature and efficiency of solar thermal systems. Inspired by low-cost mini-actuators used for car wing mirrors, we examine the economic feasibility of a heliostat with individually adjustable mini-facets to correct astigmatic effects, and we compare three alternative tracking configurations.

  2. [Toric intraocular lenses. Clinical results and rotational stability].

    Science.gov (United States)

    Gerten, G; Michels, A; Olmes, A

    2001-08-01

    Correction of an astigmatism at the time of cataract surgery can be achieved in two different ways, by alteration of the corneal curvature or by implantation of a toric intraocular lens (toric IOL). In the latter, in addition to the wound architecture and IOL calculation, the influence of rotational stability in the capsular bag is most important for the refractive result. This retrospective study included 26 eyes from 24 patients with a corneal astigmatism of 2.5-11 D before cataract surgery of which 24 eyes showed a congenital astigmatism and 2 eyes an astigmatism after keratoplasty. After phakoemulsification a three-piece toric PMMA customised IOL (6.5/13.75 mm) was implanted into the capsular bag. Subjective and objective refraction as well as keratometry and corneal topography were performed pre- and postoperatively. The axis of the toric IOL cylinder was marked and could be measured precisely in the postoperative period. The surgically induced astigmatism (SIA) was calculated. At a mean follow-up time of 12 months after the implantation of a toric IOL, all eyes showed a reduction of total astigmatism. The mean total refractive astigmatism could be reduced from 4.16 D +/- 1.58 D preoperatively to 1.64 D +/- 1.21 D postoperatively. In 6 out of the 26 eyes (23%) the toric IOL rotated more than 10 degrees in the capsular bag and in all 6 cases the IOL rotation happened in the first 3 weeks postoperation. The IOL position was surgically corrected within 3-6 weeks after initial surgery and remained stable during the follow-up period. The implantation of a PMMA toric IOL is a promising procedure to correct higher levels of corneal astigmatism in cataract surgery. The initial rotational stability of the haptics in the capsular bag still has to be improved and the corneal SIA has to be reduced by smaller incisions. Therefore, three-piece foldable IOLs with a new haptic design are under development.

  3. Biomechanical Modeling of Pterygium Radiation Surgery: A Retrospective Case Study

    OpenAIRE

    Pajic, Bojan; Aebersold, Daniel M.; Eggspuehler, Andreas; Theler, Frederik R.; Studer, Harald P.

    2017-01-01

    Pterygium is a vascularized, invasive transformation on the anterior corneal surface that can be treated by Strontium-/Yttrium90 beta irradiation. Finite element modeling was used to analyze the biomechanical effects governing the treatment, and to help understand clinically observed changes in corneal astigmatism. Results suggested that irradiation-induced pulling forces on the anterior corneal surface can cause astigmatism, as well as central corneal flattening. Finite element modeling of c...

  4. The evolution of refractive status in Chinese infants during the first year of life and its affected factors

    Directory of Open Access Journals (Sweden)

    Shu-Juan Yu

    2017-08-01

    Full Text Available AIM: To study the evolution of the refractive status and examine the affected factors in infants during the first year of life in a large sample size in China. METHODS: A total of 1258 babies (2516 eyes aged 32wk gestational age to 1y participated in the study, including 766 premature and 492 full-term infants. First, each baby received an orthoptic examination, slit-lamp checking and fundus imaging. Patients with diseases which might affect refractive status were excluded from the cohort. The cycloplegia retinoscopy was performed. Their neonatal histories were reviewed. Each measurement contained the refractive status and calculation of the spherical equivalent (SE. RESULTS: Refractive state showed an average hyperopia of +0.94±1.63 D at early ages, followed by a trend toward more hyperopia. The refractive state reached the top (+2.43±1.46 D at the age of one to two months. Then gliding till one year old when the refractive state reached +0.59±1.41 D. The prevalence of astigmatism was 42.17% in the study, being 2.82% myopic astigmatism and 39.35% hyperopic astigmatism. The 94.1% of hyperopic astigmatism was with-the-rule astigmatism and 71.83% of myopic astigmatism was with-the-rule astigmatism. Refractive state between boys and girls was different. The mean SE of boys was +1.97±1.57 D, while that of girls was +1.79±1.46 D, and the difference was significant. CONCLUSION: Before one year old, the change of refractive status is associated with checking age and sex. At the age of one to two months, the degree of hyperopia reaches the top. Boys have more hyperopic degree than girls, and with-the-rule astigmatism is predominant. Excluding premature infants with advanced retinopathy of prematurity, premature and full-term children have same refraction status.

  5. Clinical research of limbal relaxing incision during implantable collamer lens surgery

    Directory of Open Access Journals (Sweden)

    Zhen Li

    2015-02-01

    Full Text Available AIM: To evaluate the efficacy and safety of limbal relaxing incision(LRIfor correcting corneal astigmatism during implantable collamer lens(ICLsurgery.METHODS: A total of 185 eyes of 105 patients with high myopia and corneal keratometric astigmatism were included in the study. ICL surgery with concomitant relaxing incision was performed in 105 eyes of 60 patients in LRIs group(Group A. Eighty eyes of 45 patients only underwent ICL surgery were in control group(Group B. All patients undergone ophthalmic examination that included uncorrected visual acuity(UCVA, best-corrected visual acuity(BCVA, Pentacam analysis system to observe the changes of corneal astigmatism before and 1wk, 1 and 3mo after surgery.RESULTS: Respectively comparing UCVA between two groups in 1 and 3mo postoperatively, the P values were considered statistically significant(PP values were considered no statistically significant(P>0.05. Preoperative corneal astigmatism was 1.52±0.55D in group A and 1.48±0.57D in group B, there was no statistically significant difference(P>0.05. One week postoperatively, the astigmatism was 0.55±0.41D in group A and 1.20±0.48D in group B. One month postoperatively, the astigmatism was 0.60±0.38D in group A and 0.93±0.47D. Three months postoperatively, the astigmatism was 0.51±0.32D in group A and 0.96±0.40D in group B. The difference between the two groups were statistically significant(PPPCONCLUSION: LRIs performed during ICL surgery appeared to be an effective and safer procedure to reduce pre-existing corneal astigmatism and improve UCVA as well as the visual quality.

  6. [Pitfalls in the determination of distance glasses].

    Science.gov (United States)

    Lachenmayr, B

    2011-04-01

    The correct determination of distance glasses depends on a correct objective refraction and a subject determination of power and axis of a possible astigmatism in both a coarse and fine manner. In suitable cases a binocular fine refraction under polarized conditions with a red-green test should be performed. Special considerations have to be taken into account in cases of high unilateral congenital or acquired astigmatism as well as in case of congenital or acquired anisometropia or aniseiconia.

  7. [Limbal relaxing incisions during cataract surgery: one-year follow-up].

    Science.gov (United States)

    Arraes, João Carlos; Cunha, Fernando; Arraes, Tatiana Azevedo; Cavalvanti, Ronald; Ventura, Marcelo

    2006-01-01

    To evaluate astigmatism variation between preoperative, 1st and 12th postoperative month of patients who underwent cataract surgery with limbal relaxing incisions (LRI) aiming to reduce the preoperative astigmatism. Sixteen patients who underwent cataract surgery by the phacoemulsification technique with a 5.5 mm escleral incision, at the Altino Ventura Foudation, between April and July of 2002. The limbal relaxing incisions were performed according to Gills' modified nomogram (1D - 1 LRI of 6 mm; 1-2D - 2 LRI of 6 mm; 2-3D - 2 LRI of 8 mm). They were done in the most curved meridians, determined by preoperative corneal topography. Significant reduction in preoperative astigmatism was observed in the 1st postoperative month in 2 limbal relaxing incisions of the 6 mm group (57% topographic astigmatism and 87% refractional) and in 2 limbal relaxing incisions of the 8 mm group (50% topographic astigmatism and 65% refractional), maintaining the reduction with no significant alteration until the 12th postoperative month. The 1 limbal relaxing incision of the 6 mm group did not yield significant astigmatism reduction, but there was no significant alteration until de 12th postoperative month. There were also no complications such as postoperative discomfort, glare, aniseiconia, diplopia, incision infection and corneal thinning or ectasia. Two limbal relaxing incisions of 8 and 6 mm aiming to correct preoperative astigmatism of 2 to 3D and 1 to 2D, respectively, were safe and effective with a stable effect in the first postoperative follow-up year. The 1 limbal relaxing incision of 6 mm aiming to reduce 1 diopter of preoperative astigmatism was not effective, but it did not induce any significant postoperative complications.

  8. Color light-emitting diode reflection topography: validation of keratometric repeatability in a large sample of wide cylindrical-range corneas

    OpenAIRE

    Kanellopoulos AJ; Asimellis G

    2015-01-01

    Anastasios John Kanellopoulos,1,2 George Asimellis11LaserVision.gr Clinical and Research Eye Institute, Athens, Greece; 2New York University Medical School, New York, NY, USAPurpose: To investigate repeatability of steep and flat keratometry measurements, as well as astigmatism axis in cohorts with normal range and regular astigmatic such as: eyes following laser-assisted in situ keratomileusis (LASIK) and normal population, as well as cohorts of high and irregular astigmati...

  9. Identical twins with “mirror image” anisometropia and esotropia

    Directory of Open Access Journals (Sweden)

    Stanković-Babić Gordana

    2011-01-01

    Full Text Available Introduction. Identical twins account for 0.2% of the world population and 8% of all twins. A “mirror image” variation can be found in 25% of identical twins. Studies of twins assume a special place in human genetics due to the possibility of comparing genetic and other factors. We present two pairs of identical male twins with mirror-image astigmatism and esotropia. Case Outline. The first was a pair of twelve-year old identical twins with “mirror image” myopic astigmatism. The Twin 1 had myopic astigmatism in the right eye, while the Twin 2 was affected by the left eye myopic astigmatism. The second was a pair of six-year old identical twins with esotropia and hypermetropic astigmatism. The Twin 1 had esotropia in the left eye, while the right eye was affected in the Twin 2. Esotropia was surgically corrected. Conclusion. In this study we pointed to the role of genetic factors in the development of refractive error, as well as the type of strabismus. Refraction anomalies (myopia, hypermetropia and astigmatism are complex heterogeneous disorders and ideal for genetic investigation. The knowledge of genetic mechanisms involved in refractive error susceptibility may allow treatment to prevent progression or to further examine gene-environment interactions. We hope that this paper will initiate further investigation of refraction anomalies in twins and future multicentre studies, which, to our knowledge, have not been conducted in our country so far.

  10. Identical twins with "mirror image" anisometropia and esotropia.

    Science.gov (United States)

    Stanković-Babić, Gordana; Vujanović, Milena; Cekić, Sonja

    2011-01-01

    Identical twins account for 0.2% of the world population and 8% of all twins. A "mirror image" variation can be found in 25% of identical twins. Studies of twins assume a special place in human genetics due to the possibility of comparing genetic and other factors. We present two pairs of identical male twins with mirror-image astigmatism and esotropia. The first was a pair of twelve-year old identical twins with "mirror image" myopic astigmatism. The Twin 1 had myopic astigmatism in the right eye, while the Twin 2 was affected by the left eye myopic astigmatism. The second was a pair of six-year old identical twins with esotropia and hypermetropic astigmatism. The Twin 1 had esotropia in the left eye, while the right eye was affected in the Twin 2. Esotropia was surgically corrected. In this study we pointed to the role of genetic factors in the development of refractive error, as well as the type of strabismus. Refraction anomalies (myopia, hypermetropia and astigmatism) are complex heterogeneous disorders and ideal for genetic investigation. The knowledge of genetic mechanisms involved in refractive error susceptibility may allow treatment to prevent progression or to further examine gene-environment interactions. We hope that this paper will initiate further investigation of refraction anomalies in twins and future multicentre studies, which, to our knowledge, have not been conducted in our country so far.

  11. Preliminary observation of refractive cataract surgery assisted by femtosecond laser

    Directory of Open Access Journals (Sweden)

    Xiao-Li Wang

    2015-12-01

    Full Text Available AIM:To compare the differences of visual acuity and corneal astigmatism postoperatively between conventional refractive cataract surgery and that assisted by femtosecond laser.METHODS:Sixty patients(60 eyeswith age-related cataract and cornea astigmatism were divided into femtosecond group and conventional group randomly or voluntarily. The flat shaft, steep shaft and diopter of corneal astigmatism in patients in femtosecond group were inputted into the online vector calculators to get the location and width of the incision. Then femtosecond laser was used to make corneal releasing incision, the main and auxiliary incision. Phacoemulsification and aspheric multifocal intraocular lens implantation were undergone. Patients in conventional group received full-thickness relaxing incision by cornea paracentesis knife at the steepest meridian axis during phacoemulsification. Then aspheric multifocal intraocular lenses were implanted. Uncorrected distance visual acuity(UCDVA, uncorrected near visual acuity(UCNVAand cornea astigmatism were observed at 1d,1wk and 1mo postoperative. RESULTS:UCVA of patients in both groups was improved after the surgeries. UCDVA and UCNVA of femtosecond group were higher than those of conventional group, while the cornea astigmatism of femtosecond group was lower than that of conventional group.CONCLUSION:Refractile cataract surgery assisted by femtosecond laser canoffer better visual quality than conventional refractive cataract surgery because of lower cornea astigmatism and better visual acuity.

  12. Gas permeable toric use and applications: survey of Section on Cornea and Contact Lens Diplomates of the American Academy of Optometry.

    Science.gov (United States)

    Blackmore, Karen; Bachand, Nicci; Bennett, Edward S; Henry, Vinita A

    2006-01-01

    The purpose of this study was to survey Diplomates in the Section on Cornea and Contact Lenses of the American Academy of Optometry (AAO) to determine their fitting preferences for astigmatic patients, lens materials used, and their perception of simplicity or complexity of bitoric fitting. A total of 180 practitioners, representing all active Diplomates in the Cornea and Contact Lens Section, were sent a survey of 11 questions pertaining to their astigmatic contact lens prescribing habits. Sixty-eight (38%) of those surveyed responded to the questionnaire. The results of this survey included the following: (1) gas permeable (GP) lenses represented 28.7% of all contact lenses fit; (2) a spherical power effect (SPE) bitoric lens was preferred (versus four other options) by 58.8% of respondents for a 3.5 diopter (D) refractive astigmat with no residual astigmatism, whereas a cylinder power effect (CPE) bitoric was preferred by 55.9% for a 3.5 D refractive astigmatic with more than 1 D of residual astigmatism; (3) only 10.4% of responding practitioners consider GP torics to be difficult to fit. (1) Back surface toric and bitoric GP lenses are considered easy to design and fit by most Diplomates. (2) The Mandell-Moore guide is the preferred empirical method, and the Polycon SPE is the preferred diagnostic fitting method for bitoric lenses for those responding to the survey.

  13. Keratometry device for surgical support

    Directory of Open Access Journals (Sweden)

    Saia Paula

    2009-12-01

    Full Text Available Abstract Background High astigmatisms are usually induced during corneal suturing subsequent to tissue transplantation or any other surgery which involves corneal suturing. One of the reasons is that the procedure is intimately dependent on the surgeon's skill for suturing identical stitches. In order to evaluate the influence of the irregularity on suturing for the residual astigmatism, a prototype for ophthalmic surgical support has been developed. The final intention of this prototype is to be an evaluation tool for guided suture and as an outcome diminish the postoperative astigmatism. Methods The system consists of hand held ring with 36 infrared LEDs, that is to be projected onto the lachrymal film of the cornea. The image is reflected back through the optics of the ocular microscope and its distortion from the original circular shape is evaluated by developed software. It provides keratometric and circularity measurements during surgery in order to guide the surgeon for uniformity in suturing. Results The system is able to provide up to 23D of astigmatism (32D - 55D range and is ± 0.25D accurate. It has been tested in 14 volunteer patients intraoperative and has been compared to a commercial keratometer Nidek Oculus Hand-held corneal topographer. The correlation factors are 0.92 for the astigmatism and 0.97 for the associated axis. Conclusion The system is potentially efficient for guiding the surgeon on uniformity of suturing, presenting preliminary data indicating an important decrease on the residual astigmatism, from an average of 8D - for patients not submitted to the prototype guidance - to 1.4D - for patients who have actually been submitted to the prototype guidance - after the first 24 hours post-surgery and in the subsequent weeks. It also indicates that the surgeon should achieve circularity greater or equal to 98% in order to avoid postoperative astigmatisms over 1D. Trial Registration Trial registration number: CAAE - 0212.0.004.000-09.

  14. Timing of eyelid surgery in the setting of refractive surgery: preoperative and postoperative considerations.

    Science.gov (United States)

    Victoria, Ana C; Chuck, Roy S; Rosenberg, Jamie; Schwarcz, Robert M

    2011-07-01

    With any operation, the surgeon should be aware of predisposing factors that may lead to postoperative complications. Here we review the major factors due for consideration in both eyelid and refractive eye surgery, preoperatively and postoperatively, and consider the importance of timing to lessen the inherent risks of each procedure. Refractive surgery can affect corneal sensation by ablating the corneal nerves and can cause serious corneal complications if followed by eyelid surgery. Studies find that patients undergoing eyelid surgery have a change in astigmatic error of as much as 1.0 D during the first 3 postoperative months. The longest reported follow-up period of astigmatic changes in adult patients following eyelid ptosis surgery is 1 year and a considerable number of patients had a change in cylinder of up to 0.3 D postoperatively. Blepharoplastic surgery is also reported to cause astigmatic changes postoperatively, significantly more if entire fat pads are removed. To prevent corneal exposure, postrefractive eyelid surgery should be performed at least 6 months after lamellar ablative procedures and at least 3 months after surface ablative procedures. Refractive surgery revision may be necessary when astigmatic error occurs and should be carried out no earlier than 6 months postoperatively to allow for stabilization. Cosmetic blepharoplasty with fat pad debulking should be performed at least 6 months prior to refractive surgery to allow for any potential corneal astigmatic change to stabilize, for regained strength in the orbicularis, and for improved tear film distribution.

  15. Analysis of refractive state in 708 children with ametropic amblyopia

    Directory of Open Access Journals (Sweden)

    Ju-Fen Huang

    2016-01-01

    Full Text Available AIM: To analyze the refractive state and explore the epidemiologic feature of children with ametropic amblyopia.METHODS: This study retrospectively analyzed 708 children(1 416 eyeswith amblyopia from January 2012 to December 2013 in Special Department of Strabismus and Amblyopic and Department of Pediatric Ophthalmology in our hospital, who were diagnosed as ametropic amblyopia and accepted centrally comprehensive training. The refractive state were given epidemiologic analyze.RESULTS: In the 708 cases(1 416 eyes, there were 190 eyes with hyperopia(13.42%,612 eyes with hyperopia astigmatism(43.22%,18 eyes with myopia(1.27%,134 eyes with myopia astigmatism(9.46%,462 eyes with mixed astigmatism(32.63%. The distributions of refractive state in children at different age were different, and the difference was statistically significant(PCONCLUSION: Hyperopia ametropia and mixed astigmatism are the main types of refractive errors in amblyopia children. The level of amblyopia is related to refractive state and astigmatism axial.

  16. Effects of different types of refractive errors on bilateral amblyopia

    Directory of Open Access Journals (Sweden)

    Mücella Arıkan Yorgun

    2012-12-01

    Full Text Available Objectives: Identifying effects of different types of refractiveerrors on final visual acuity and stereopsis levels inpatients with bilateral amblyopia.Materials and methods: Patients with bilateral amblyopialower than ≥1.5 D anisometropia were included. Thepatients were classified according to the level of sphericalequivalent (0-4 D and >4 D of hypermetropia, the levelof astigmatism (below and above 2D in positive cylinderand type of composed refractive error [ 4 D of hypermetropiaand 2 D of astigmatism (group III]. Initialand final binocular best corrected visual acuities (BCVAwere compared between groups.Results: The initial binocular BCVA levels were significantlylower in patients with > 4 D of hypermetropia(p=0.028, without correction after treatment (p=0.235.The initial binocular BCVA was not different betweenastigmatism groups, but final BCVA levels were significantlylower in 4-6D of astigmatism compared with 2-4D of astigmatism (p=0.001. During comparison of composedrefractive errors, only the initial binocular BCVAwas significantly lower in group I compared to group II(p=0.015. The final binocular BCVA levels were not differentbetween groups I and III (p>0.05.Conclusions: Although the initial BCVA is lower in patientswith higher levels of hypermetropia, the response ofpatients to treatment with glasses is good. The responseof patients with high levels of astigmatism seems to belimited. J Clin Exp Invest 2012; 3(4: 467-471Key words: Amblyopia, isoametropic amblyopia, hypermetropia,refractive amblyopia, visual acuity

  17. In vivo and in vitro analysis of topographic changes secondary to DSAEK venting incisions

    Directory of Open Access Journals (Sweden)

    Church D

    2011-08-01

    Full Text Available Majid Moshirfar, Monette T Lependu, Dane Church, Marcus C Neuffer John A Moran Eye Center, University of Utah, Salt Lake City, UT, USA Introduction: Descemet’s stripping automated endothelial keratoplasty (DSAEK venting incisions may induce irregular corneal astigmatism. The study examines in vivo and in vitro astigmatic effects of venting incisions. Patients and methods: In vivo analysis examined eleven eyes of eleven patients who had received DSAEK with venting incisions. A chart review of the eleven eyes including assessment of pre and postoperative refraction and topography was performed. In vitro analysis examined three cadaver eyes which received topographic imaging followed by venting incisions at 4 mm, 6 mm, and 7 mm optical zones. Topographic imaging was then performed again after the incisions. Results: Postoperative topographies of eleven eyes demonstrated localized flattening at incision sites and cloverleaf pattern astigmatism. There was a significant difference in corneal irregularity measurement (P = 0.03, but no significant difference in shape factor or change of topographic cylinder. The cloverleaf pattern was found in cadaver eyes with incisions placed at 4 mm and 6 mm optical zones but not at the 7 mm zone. Conclusion: DSAEK venting incisions can cause irregular corneal astigmatism that may affect visual outcomes. The authors recommend placement of venting incisions near the 7 mm optical zone. Keywords: DSAEK, venting incisions, endothelial keratoplasty, astigmatism, endothelium, endothelial transplant

  18. Evaluation of different types of lamellar keratoplasty for treatment of peripheral corneal perforation.

    Science.gov (United States)

    Huang, Ting; Wang, Yujuan; Ji, Jianping; Gao, Na; Chen, Jiaqi

    2008-08-01

    To discuss the efficacy and visual outcomes of different types of lamellar keratoplasty (LK) for the treatment of peripheral corneal perforation. Sixty patients (67 eyes) with peripheral corneal perforation underwent semilunar LK (16 eyes), crescentic LK (12 eyes), biconvex LK (13 eyes), annular LK (11 eyes) and total LK (15 eyes) respectively. The applied type of LK for each involved eye was decided by different sizes and shapes of corneal ulceration and perforation. Postoperative visual acuity (VA), corneal astigmatism and postoperative complications were studied during a 7- to 21-month follow-up. VA showed no statistical difference preoperatively (P = 0.18), but it was statistically different postoperatively (P astigmatism in different types of LK was statistically different (P astigmatism, while biconvex LK had the highest. The main postoperative complications were leakage at the graft-host interface, graft rejection and initial disease recurrence. LK is an effective procedure in eyes with peripheral corneal perforation. Different sizes and shapes of LK can influence postoperative VA due to different degrees of astigmatism. Yet postoperative astigmatism can be reduced by making well-matched grafts and preserving the uninvolved tissue to the largest extent.

  19. Clinical Outcomes of Penetrating Keratoplasty Performed with the VisuMax Femtosecond Laser System and Comparison with Conventional Penetrating Keratoplasty

    Science.gov (United States)

    Kamiya, Kazutaka; Kobashi, Hidenaga; Shimizu, Kimiya; Igarashi, Akihito

    2014-01-01

    Purpose To assess the clinical outcomes of femtosecond laser-assisted keratoplasty (FLAK) using the VisuMax femtosecond laser system, and to compare them with those of conventional penetrating keratoplasty (PK). Methods We retrospectively examined 20 eyes of 20 consecutive patients undergoing FLAK and 20 eyes of 20 age- and diagnosis-matched patients undergoing conventional PK. We quantitatively assessed corneal astigmatism, refractive astigmatism, and corrected visual acuity, 1, 3, and 6 months postoperatively, and endothelial cell density 6 months postoperatively. Results Corneal and refractive astigmatism after FLAK were significantly lower after FLAK than that after conventional PK at 3 and 6 months postoperatively (p = 0.04 and p = 0.03, respectively, Mann-Whitney U test). FLAK provided significantly faster visual recovery than conventional PK at 1 month postoperatively (p = 0.02), but not at 3 and 6 months postoperatively (p = 0.52 and p = 0.80, respectively). We found no significant differences in the change in endothelial cell density between the two groups (p = 0.30). Conclusions FLAK using the VisuMax femtosecond laser system induces significantly less corneal and refractive astigmatism than conventional PK, and provides significantly faster visual recovery in the early postoperative period, possibly because the geometry of the donor-recipient matching is more physiological and requires less tight sutures. It is suggested that FLAK has advantages over conventional PK, in terms of astigmatism and fast visual recovery. PMID:25126741

  20. Clinical outcomes of penetrating keratoplasty performed with the VisuMax femtosecond laser system and comparison with conventional penetrating keratoplasty.

    Directory of Open Access Journals (Sweden)

    Kazutaka Kamiya

    Full Text Available To assess the clinical outcomes of femtosecond laser-assisted keratoplasty (FLAK using the VisuMax femtosecond laser system, and to compare them with those of conventional penetrating keratoplasty (PK.We retrospectively examined 20 eyes of 20 consecutive patients undergoing FLAK and 20 eyes of 20 age- and diagnosis-matched patients undergoing conventional PK. We quantitatively assessed corneal astigmatism, refractive astigmatism, and corrected visual acuity, 1, 3, and 6 months postoperatively, and endothelial cell density 6 months postoperatively.Corneal and refractive astigmatism after FLAK were significantly lower after FLAK than that after conventional PK at 3 and 6 months postoperatively (p = 0.04 and p = 0.03, respectively, Mann-Whitney U test. FLAK provided significantly faster visual recovery than conventional PK at 1 month postoperatively (p = 0.02, but not at 3 and 6 months postoperatively (p = 0.52 and p = 0.80, respectively. We found no significant differences in the change in endothelial cell density between the two groups (p = 0.30.FLAK using the VisuMax femtosecond laser system induces significantly less corneal and refractive astigmatism than conventional PK, and provides significantly faster visual recovery in the early postoperative period, possibly because the geometry of the donor-recipient matching is more physiological and requires less tight sutures. It is suggested that FLAK has advantages over conventional PK, in terms of astigmatism and fast visual recovery.

  1. Intraoperative videokeratography in penetrating keratoplasty and excimer laser-assisted lamellar keratoplasty for keratoconus.

    Science.gov (United States)

    Spadea, Leopoldo; Fiasca, Arianna; Federici, Simone

    2010-09-01

    To evaluate the usefulness of intraoperative computerized corneal topographic data in excimer laser-assisted lamellar keratoplasty (ELLK) and penetrating keratoplasty (PK). Prospective, comparative, interventional case series. Intra- and postoperative videokeratography (Keratron Scout) evaluation was performed on 30 eyes of 30 consecutive patients affected by keratoconus (16 men and 14 women; mean age 32.63±8.02 years) submitted to ELLK (15 eyes) using 16 interrupted 10-0 nylon stitches or to PK (15 eyes) using a 12-bite 10-0 nylon double-running continuous suture. In the ELLK group, the mean intraoperative keratometric astigmatism was 12.06±4.86 diopters (D), which changed to 5.19±2.51 D after topography-guided intraoperative suture adjustment. In the PK group, intraoperative keratometric astigmatism was 10.18±3.88 D, which changed to 3.49±0.41 D. After 24 months (sutures out), the mean videokeratographic keratometric astigmatism was 3.35±1.96 D in the ELLK group and 3.37±0.92 D in the PK group. The Alpins method of vector analysis showed some significant changes especially in the ELLK group. In keratoplasty surgery, videokeratography is useful for suture adjustment. In the PK group, using a double-running suture technique, the postoperative astigmatism (after all sutures were removed) was similar to the astigmatism measured intraoperatively by videokeratography. Copyright 2010, SLACK Incorporated.

  2. Prospects for electron beam aberration correction using sculpted phase masks

    Energy Technology Data Exchange (ETDEWEB)

    Shiloh, Roy, E-mail: royshilo@post.tau.ac.il; Remez, Roei; Arie, Ady

    2016-04-15

    Technological advances in fabrication methods allowed the microscopy community to take incremental steps towards perfecting the electron microscope, and magnetic lens design in particular. Still, state of the art aberration-corrected microscopes are yet 20–30 times shy of the theoretical electron diffraction limit. Moreover, these microscopes consume significant physical space and are very expensive. Here, we show how a thin, sculpted membrane is used as a phase-mask to induce specific aberrations into an electron beam probe in a standard high resolution TEM. In particular, we experimentally demonstrate beam splitting, two-fold astigmatism, three-fold astigmatism, and spherical aberration. - Highlights: • Thin membranes can be used as aberration correctors in electron columns. • We demonstrate tilt, twofold-, threefold-astigmatism, and spherical aberrations. • Experimental and physical-optics simulation results are in good agreement. • Advantages in cost, size, nonmagnetism, and nearly-arbitrary correction.

  3. Sclerocorneal Intrastromal Lamellar Keratoplasty for Pellucid Marginal Degeneration.

    Science.gov (United States)

    Guindolet, Damien; Petrovic, Alexandra; Doan, Serge; Cochereau, Isabelle; Gabison, Eric E

    2016-06-01

    Surgical management of advanced pellucid marginal degeneration is challenging. To correct both corneal thinning and induced corneal astigmatism, we propose a modified intrastromal lamellar sclero-keratoplasty. Corneal thinning was mapped using perioperative optical coherence tomography (OCT). Then through a scleral tunnel, an intrastromal pocket was created by stromal lamellar dissection under OCT guidance. A 300 μm-thick stromal lamellar graft was inserted in that pocket before closing the sclera to increase vertical median keratometry. Intrastromal lamellar sclero-keratoplasty enabled corneal thinning correction and increased corneal astigmatism correction (-11.6 diopters) without complications. Intrastromal lamellar keratoplasty with scleral tunnel is efficient in PMD. Corneal thinning is corrected with the intrastromal lamellar keratoplasty, and scleral tunnel closure allows increased corneal astigmatism correction. Perioperative OCT guidance allows better detection of the diseased cornea and is helpful for the lamellar dissection.

  4. "Top hat"-shaped penetrating keratoplasty using the femtosecond laser.

    Science.gov (United States)

    Steinert, Roger F; Ignacio, Teresa S; Sarayba, Melvin A

    2007-04-01

    To determine the feasibility of using a modified femtosecond laser to perform penetrating corneal resections. Controlled laboratory study. Fourteen corneoscleral rims were mounted on an artificial anterior chamber. Eight underwent traditional penetrating keratoplasty (PKP) and six underwent "top hat"-shaped PKP using a femtosecond laser. Wound leakage pressure and induced astigmatism were compared between the two groups. Deep corneal resection with the femtosecond laser was feasible. Wound leakage occurred at 38 +/- 11 mm Hg in the traditional PKP eyes and at 240 +/- 69 mm Hg in the laser-shaped PKP groups. Initial induced astigmatism was 3.76 +/- 0.82 diopters and 3.46 +/- 1.36 diopters in the traditional and shaped PKP groups, respectively. Shaped PKP using the femtosecond laser is feasible and provides superior incision integrity compared to traditional PKP. Initial induced astigmatism is dominated by suture effects.

  5. Non phaco suture less cataract extraction through temporal approach.

    Science.gov (United States)

    Junejo, Sameen Afzal; Jatoi, Shafi Muhammad; Khan, Nisar Ahmed

    2009-01-01

    Non Phaco suture less cataract extraction through temporal approach retains most of the advantages of phacoemulsification but can be delivered at lower cost with better visual out come. Extra capsular cataract extraction followed by posterior chamber intraocular lens implantation was performed, on 300 eyes of 250 patients. The technique involved was posterior limbal corneal tunnel incision through temporal approach, followed by implantation of PMMA posterior chamber intraocular lens. Visual acuity at the time of discharge, third post operative week and sixth week was recorded. Surgically induced astigmatism was reported. The uncorrected visual acuity at discharge was 6/18 or better in 63.2% eyes. The best corrected visual acuity was 6/9 and better in 96.0% subjects at six weeks. Poor visual outcome (astigmatism, as the corneal incision was given through temporal approach. Suture less manual extra capsular cataract surgery through temporal approach ensures rapid visual recovery with minimum astigmatism against rule.

  6. Analysis of corneal refractive power after small incision surgery of non-phacoemmulsification for high myopic eyes with cataract

    Directory of Open Access Journals (Sweden)

    Xia Ye

    2016-04-01

    Full Text Available AIM: To evaluate the changes of corneal refractive power and surgically induced astigmatism(SIAafter small incision non-phacoemmulsification surgery for high myopic eyes with cataract in middle aged and senile people. METHODS: A retrospective study was done in 145 eyes of 103 middle aged and senile patients with high myopia and cataract who underwent small incision non-phacoemulsification surgery in our hospital. The keratometer was used to measure corneal horizontal refractive power(K1, vertical corneal refractive power(K2and their axial on postoperative 3d, 1wk, 1 and 3mo. SIA was calculated by sine law and cosine law method. RESULTS: There was statistically significant difference on average corneal astigmatism at 3d and 1wk compared with that before surgeries(PPPPCONCLUSION: Corneal astigmatism is a little larger in short term after small incision non-phacoemulsification surgery for high myopia patients with cataract. The surgery method needed to be improved.

  7. Comparison of fitting stability of the different soft toric contact lenses

    OpenAIRE

    Momeni-Moghaddam, Hamed; Naroo, Shehzad A; Askarizadeh, Farshad; Tahmasebi, Fatemeh

    2014-01-01

    Purpose: To compare lens orientation and rotational recovery of five currently available soft toric lenses. Methods: Twenty subjects were recruited and trialed with each of the study lenses in a random order. Study lenses were PureVision® Toric (B&L), Air Optix® for Astigmatism (Alcon), Biofinity® Toric (CooperVision), Acuvue® Advance for Astigmatism (Vistakon), and Proclear® Toric (CooperVision). Lens orientation in primary position to determine the lens rotation form the vertical position a...

  8. Mitomycin C "straight scleral tunnel incision"--trabeculectomy with a releasable suture.

    Science.gov (United States)

    Wang, Lin-nong; Fang, Fang; Zhang, Yang; Chen, Li-xun; Zhao, Tai-hong; Xiao, Lei; Tang, Hong

    2006-09-01

    To evaluate the efficacy of "straight scleral tunnel incision" -trabeculectomy with a releasable suture supplemented with mitomycin C (MMC) on reducing intraocular pressure (IOP), complications, and corneal astigmatism in patients with primary angle-closure glaucoma (PACG). Totally 217 acute or chronic PACG patients with occludable angle above 180 degrees and IOP above 21 mm Hg were divided into 3 groups. Patients in group A (98 cases, 128 eyes), B (71 cases, 95 eyes), and C (48 cases, 60 eyes) were treated with "straight scleral tunnel incision"-trabeculectomy with a releasable suture supplemented with MMC, releasable suture trabeculectomy with MMC, and trabeculectomy with MMC, respectively. IOP, complications, and surgically induced astigmatism (SIA) were evaluated preoperatively and up to 12 months postoperatively. IOP of 2 weeks after treatment was significantly lower than preoperative IOP in all the 3 groups (all P astigmatism among the 3 groups. The corneal astigmatism after 2 weeks in group A (1.71 +/- 1.47D) was higher than that before operation (1.28 +/- 1.05D, P = 0.126). With 12 months gone, the astigmatism almost returned to preoperative levels. The corneal astigmatisms after 2 weeks in group B and C (1.99 +/- 1.20D and 2. 22 +/- 1.39D) were significantly higher than those before operation (1.20 +/- 0.85D and 1.18 +/- 0.93D, P = 0.002, P = 0.001), respectively. With 12 months gone, the mean astigmatisms in group B and C (1.87 +/- 0.91D and 1.90 +/- 1.16D) were still significantly higher than those before operation (P = 0.001, P = 0.003). The highest astigmatic polar values in group A, B, and C (1.00D, 1. 89D, and 1. 77D) occurred after 2 weeks, 1 month, and 1 month postoperation, respectively, which were significantly higher than those before operation (0.19 +/- 1.32D, 0.12 +/- 1.22D, and 0.17 +/- 1.25D, P incision" -trabeculectomy with a releasable suture supplemented with MMC can reduce complications and get satisfactory results in reducing IOP and

  9. Programa de perfeccionamiento de la técnica de la microcirugía ocular Ocular microsurgery technique improvement program

    Directory of Open Access Journals (Sweden)

    Edith Ballate Nodales

    1999-12-01

    Full Text Available Basados en las numerosas técnicas de microcirugía de la catarata que tratan de perfeccionar este acto quirúrgico y disminuir el astigmatismo residual, se propone un programa computadorizado que recoge los cálculos del astigmatismo y la aniseiconia, útil para investigaciones posteriores y un manual del usuario.On the basis of a number of cataract microsurgical techniques that try to improve this surgical procedure and diminish the residual astigmatism, we proposed a computerized program that covers astigmatism and aniseikonia calculations; useful for future research works, and a user's manual.

  10. Advances in femtosecond laser technology

    Directory of Open Access Journals (Sweden)

    Callou TP

    2016-04-01

    Full Text Available Thais Pinheiro Callou, Renato Garcia, Adriana Mukai, Natalia T Giacomin, Rodrigo Guimarães de Souza, Samir J Bechara Department of Ophthalmology, University of Sao Paulo, Sao Paulo, Brazil Abstract: Femtosecond laser technology has become widely adopted by ophthalmic surgeons. The purpose of this study is to discuss applications and advantages of femtosecond lasers over traditional manual techniques, and related unique complications in cataract surgery and corneal refractive surgical procedures, including: LASIK flap creation, intracorneal ring segment implantation, presbyopic treatments, keratoplasty, astigmatic keratotomy, and intrastromal lenticule procedures. Keywords: laser therapy, refractive surgical procedures, intracorneal ring, laser in situ keratomileusis, keratoplasty, presbyopia, cataract extraction, astigmatism surgery

  11. Wound construction in manual small incision cataract surgery

    Science.gov (United States)

    Haldipurkar, S S; Shikari, Hasanain T; Gokhale, Vishwanath

    2009-01-01

    The basis of manual small incision cataract surgery is the tunnel construction for entry to the anterior chamber. The parameters important for the structural integrity of the tunnel are the self-sealing property of the tunnel, the location of the wound on the sclera with respect to the limbus, and the shape of the wound. Cataract surgery has gone beyond just being a means to get the lens out of the eye. Postoperative astigmatism plays an important role in the evaluation of final outcome of surgery. Astigmatic consideration, hence, forms an integral part of incisional considerations prior to surgery. PMID:19075401

  12. Prevalence of common visual problems among primary school ...

    African Journals Online (AJOL)

    Hypermetropia predominated (7.8%), followed by myopia (3.6%) and astigmatism (3.5%). Ninety percent of the children with vision less than 6/6 in any eye could have their vision improved by refractive complications and disability. A total of 62.4% of these children with visual disability could have their functional vision in ...

  13. A review of corneal melting following kerato-refractive surgery.

    Science.gov (United States)

    Hodge, Christopher; Chan, Colin; Bali, Shveta Jindal; Sutton, Gerard

    2013-01-01

    Corneal melting is a rare complication that may occur following a number of different types of surgery. Keratolysis may lead to scarring, irregular astigmatism, photophobia and decreased vision. This article reviews the incidence, pathophysiology and treatment of this condition in kerato-refractive surgery. © 2012 The Authors; Clinical and Experimental Optometry © 2012 Optometrists Association Australia.

  14. Topography-guided laser refractive surgery.

    Science.gov (United States)

    Holland, Simon; Lin, David T C; Tan, Johnson C H

    2013-07-01

    Topography-guided laser refractive surgery regularizes the front corneal surface irregularities to achieve the desired refractive outcome. This is particularly applicable in highly aberrated corneas, where wavefront aberrometry is often not possible. This article aims to review the recently published results of topography-guided ablations in normal regular corneas, highly aberrated corneas, and its application in conjunction with collagen cross-linking (CXL) in cases of keratectasia. Topography-guided laser ablation is increasingly used with good efficacy and safety outcomes in highly aberrated corneas with irregular astigmatism. These include eyes with refractive surgery complications including postlaser in-situ keratomileusis ectasia, decentered ablation, small optical zones, asymmetrical astigmatism, and postradial keratectomy astigmatism. Further indications are for postkeratoplasty astigmatism and keratoconus. Simultaneous topography-guided ablations with CXL in keratectasia have been promising, both in addressing the surface irregularities and progressive nature of the conditions. Topography-guided laser refractive surgery is proving to be effective and well tolerated in the visual rehabilitation of highly aberrated eyes, with increasing predictability based on the recent research.

  15. Corneal Topographic Changes After Eyelid Ptosis Surgery.

    Science.gov (United States)

    Savino, Gustavo; Battendieri, Remo; Riso, Monica; Traina, Salvatore; Poscia, Andrea; DʼAmico, Giovanni; Caporossi, Aldo

    2016-04-01

    To evaluate the corneal topography and the topographic changes after ptosis surgery on patients affected by congenital and acquired blepharoptosis. Twenty eyes of 17 patients affected by acquired and congenital ptosis underwent surgical correction through anterior levator complex tightening. Computerized tomography (Syrius Sistem; CSO) was used to analyze any change in corneal astigmatism (CYL), simulated keratometry, anterior corneal symmetry index front, apical keratometry front, and central corneal thickness. Visual acuity, margin reflex distance, and levator function were also measured. After surgical ptosis repair, corneal topography demonstrated a reduction in average keratometry of 0.15 ± 0.47 diopters (D) and in corneal astigmatism of 0.26 ± 1.12 D. Significant differences were found in apical keratometry front (-1.84 ± 1.76 D) and in best-corrected visual acuity (-0.18 ± 0.06 logMAR) in the postoperative examinations. Central corneal thickness did not show significant differences between preoperative and postoperative examinations. Postoperative topographic maps showed a reduction of symmetry index front (0.10 ± 0.64 D). Eyelid ptosis modifies anterior corneal surface inducing refractive errors and modifying corneal astigmatism in patients, thus affecting the quality of vision. The surgical correction of blepharoptosis induces anterior corneal surface modification, restoring corneal symmetry and regular corneal astigmatism. Postoperative corneal topography showed normal corneal contours.

  16. Anisometropia in Children from Infancy to 15 Years

    OpenAIRE

    Deng, Li; Gwiazda, Jane E.

    2012-01-01

    This study examined the prevalence of anisometropia by age and the association between anisometropia and ametropia/astigmatism. Using longitudinal data, the relationship between anisometropia at early ages (at 6 months and 5 years) and the refractive error later (at 15 years) was also investigated.

  17. The Outcome of Extracapsular and Phacoemulsification Cataract ...

    African Journals Online (AJOL)

    This study was to evaluate the post operative astigmatism and visual acuity of patients after extra capsular extraction (ECCE) and phacoemulsification (PE) for the purpose of recommending the appropriate referral time for cataract extraction. Subject's hospital file data comprising 30 ECCE and 48 PE were collected and ...

  18. Spectacles in Children‑ Do's and Don'ts

    African Journals Online (AJOL)

    Mutti DO, Mitchell GL, Jones LA, Friedman NE, Frane SL, Lin WK, et al. Accommodation, acuity, and their relationship to emmetropization in infants. Optom Vis Sci 2009;86:666-76. 6. Abrahamsson M, Fabian G, Sjöstrand J. A longitudinal study of a population based sample of astigmatic children. II. The changeability.

  19. Nationwide reduction in the number of corneal transplantations for keratoconus following the implementation of cross-linking

    NARCIS (Netherlands)

    Godefrooij, Daniel A; Gans, Renze; Imhof, Saskia M; Wisse, Robert P L

    PURPOSE: Keratoconus is characterized by corneal ectasia and irregular astigmatism, which can lead to diminished vision and corneal scarring. Approximately 10-20% of patients with keratoconus eventually require a corneal transplant. Corneal cross-linking (CXL) is a relatively new treatment that may

  20. Comparison of Long-Term Outcomes of Femtosecond Laser-Assisted Keratoplasty with Conventional Keratoplasty.

    Science.gov (United States)

    Daniel, Moritz C; Böhringer, Daniel; Maier, Philip; Eberwein, Philipp; Birnbaum, Florian; Reinhard, Thomas

    2016-03-01

    Astigmatism is a significant problem in penetrating keratoplasty. Lower astigmatism and better visual outcomes had been expected from laser-assisted penetrating keratoplasty, that is, from the top-hat, mushroom, or zig-zag cutting profiles. We report the long-term outcomes of 141 femtosecond laser-assisted penetrating keratoplasties retrospectively. We compare these outcomes with those of penetrating keratoplasty using the guided trephine system (GTS). In all, 141 femtosecond laser-assisted penetrating keratoplasties had been performed in 119 patients. The results were compared with those of conventional keratoplasty (n = 1254; visual and refractive outcomes, graft rejections, and graft failure). Follow-up averaged 33 months. In eyes with keratoconus, the time to achieve a visual acuity of 10/20 (Snellen) was shorter in the mushroom than in the GTS group. However, there was no relevant long-term difference. Graft astigmatism was higher in the laser groups [keratometric astigmatism at the end of follow-up: -4.5 ± 4 (GTS), -5.8 ± 3.3 (top-hat), -5.9 ± 3.2 D (mushroom); P keratoplasty resulted in lower rates of rejection than GTS keratoplasty (31%). There is no significant difference in the refractive and visual outcomes after femtosecond laser-assisted penetrating keratoplasty compared with GTS keratoplasty. The benefits from the use of the femtosecond laser may be limited and should be weighed against an increased risk of immune reactions, higher surgical complexity, and higher costs.

  1. The intrastromal corneal ring in penetrating keratoplasty-long-term results of a prospective randomized study.

    Science.gov (United States)

    Birnbaum, Florian; Schwartzkopff, Johannes; Böhringer, Daniel; Reinhard, Thomas

    2011-07-01

    Postoperative astigmatism after penetrating keratoplasty is a major problem in corneal transplantation. The purpose of this prospective randomized study was to evaluate the efficacy and safety of an intrastromal corneal ring after penetrating keratoplasty. Twenty patients were included, 10 of whom received an intracorneal ring (group 1) and 10 who did not (group 2, control group). Astigmatism in Orbscan corneal topography, occurrence of immune reactions, and occurrence of side effects were this study's main outcome criteria. Mean follow-up time was 27.6 ± 5.3 months. Mean astigmatism (Orbscan) was 4.4 diopters in group 1 and 4.4 diopters in group 2 (P = 0.695). Spontaneous suture rupture occurred in 5 patients with corneal ring but in none of those in the control group. We observed 3 immune reactions in 3 patients with corneal ring, whereas group 2 experienced no rejection (P keratoplasty caused no reduction in postoperative astigmatism. However, its use was statistically significantly associated with adverse events.

  2. ORIGINAL ARTICLE

    African Journals Online (AJOL)

    User

    sent in 75 (31.9%) of the children with astigmatism being the commonest form of refractive error. Anterior segment abnormalities were present in ... Keywords: Disability, eye, ear, refractive error, ocular deviation . Journal of Medical and Biomedical Sciences (2013) 2(2): 16-22. © UDS Publishers Limited All Right Reserved ...

  3. MERSILENE (POLYESTER), A NEW SUTURE FOR PENETRATING KERATOPLASTY

    NARCIS (Netherlands)

    RAMSELAAR, JAM; BEEKHUIS, WH; RIJNEVELD, WJ; VANANDEL, MV; DIJK, F; JONGEBLOED, WL

    1992-01-01

    Mersilene (polyester monofilament) seems to be suitable for penetrating keratoplasty because it is strong, shows no degradation by ultraviolet light, is insoluble, so that it can be left in situ, and offers the possibility of regulating postoperative astigmatism by suture adjustment. In 12 patients

  4. Surgical device for supporting corneal suturing

    Science.gov (United States)

    Ventura, Liliane; Oliveira, Gunter C. D.; De Groote, Jean-Jacques; Sousa, Sidney J. F.; Saia, Paula

    2009-02-01

    A system for ophthalmic surgery support has been developed in order to minimize the residual astigmatism due to the induced irregular shape of the cornea by corneal suture. The system projects 36 light spots, from LEDs, displayed in a precise circle at the lachrymal film of the examined cornea. The displacement, the size and deformation of the reflected image of these light spots are analyzed providing the keratometry and the circularity of the suture. Measurements in the range of 32D - 55D (up to 23D of astigmatism are possible to be obtained) and a self-calibration system has been designed in order to keep the system calibrated. Steel precision spheres have been submitted to the system and the results show 99% of correlation with the fabricant's nominal values. The system has been tested in 13 persons in order to evaluate its clinical applicability and has been compared to a commercial keratometer Topcon OM-4. The correlation factors are 0,92 for the astigmatism and 0.99 for the associated axis. The system indicates that the surgeon should achieve circularity >=98% in order to do not induce astigmatisms over 3D.

  5. Refractive errors in Kaduna, Nigeria | Bagaiya | Nigerian Journal of ...

    African Journals Online (AJOL)

    Conclusion: Refractive error is a common cause of visual impairment among ophthalmic patients in Kaduna. Judicious management of the meagre resources on appropriate lens category, which in this study is presbyopic lens type, cannot be overemphasized. Key Words: Hypermetropia, myopia, astigmatism. Nigerian ...

  6. Distribution of refractive errors among school children in Abia State ...

    African Journals Online (AJOL)

    Following ocular pathology screening, the subjects declared free of such were subsequently refracted both objectively and subjectively using retino scope and trial case respectively.The result showed prevalence rate of 31.05% for myopia, 19.13% for hyperopia and 7.80% for astigmatism. Furthermore, the frequency of the ...

  7. Experimental and analytical characterization of the 3D motion of particles in acoustofluidic devices

    DEFF Research Database (Denmark)

    Rossi, M.; Barnkob, Rune; Augustsson, P.

    2012-01-01

    . Astigmatism Particle Tracking Velocimetry (APTV) was used to measure the three-dimensional trajectories, velocities and accelerations of the particles. The experiments show how the acoustic radiation force dominates for the large 5-µm particles, whereas the drag force from the acoustic streaming dominates...

  8. Results of penetrating keratoplasty performed with a femtosecond laser zigzag incision initial report.

    Science.gov (United States)

    Farid, Marjan; Kim, Matthew; Steinert, Roger F

    2007-12-01

    To determine the initial outcomes of utilizing a femtosecond laser to perform penetrating keratoplasty incisions in a zigzag pattern. Retrospective consecutive surgical series. Patients undergoing full-thickness corneal transplant surgery in a referral academic practice. The IntraLase femtosecond laser performed matching donor and host zigzag incisions in a consistent pattern in 13 eyes of 13 patients. Topographically determined astigmatism, imaging of incisions by anterior segment optical coherence tomography, and best spectacle-corrected visual acuity (BSCVA). Postoperative follow-up ranged from 3 to 9 months. Mean astigmatism was astigmatism was 4.25 D from month 3 onward. Nine eyes (69%) had or =20/30 by month 3; the eighth eye had improved to 20/25 by month 6. Optical coherence tomography images showed excellent anterior and posterior wound alignment, including one eye where the running suture loosened and was fully removed before month 3. The femtosecond laser-generated zigzag incision is biomechanically stable, resulting in excellent wound apposition, wound integrity with minimal suture tension, and recovery of good levels of BSCVA with moderate astigmatism within months of surgery.

  9. Refractive stability after cataract extraction using a 6.5-millimeter scleral pocket incision with horizontal or radial sutures.

    Science.gov (United States)

    Werblin, T P

    1994-01-01

    Radial suturing of 6.5-millimeter scleral tunnel incisions following cataract surgery can create significant with-the-rule astigmatism in the immediate postoperative period. Because of the significant visual distortion and slow visual recovery seen with radial suturing, this study was undertaken to compare two other suturing techniques which induce lesser amounts of with-the-rule astigmatism in the immediate postoperative period. The refractive behavior of eyes closed with loose radial sutures and with horizontal sutures was compared to the behavior of eyes closed with the more traditional "tight" radial sutures following phacoemulsification surgery. Eyes sutured with loosely tied radial sutures demonstrated minimal with-the-rule cylinder immediately following surgery (1.25 D) and showed a more rapid stabilization of astigmatism than did the eyes tied with tight radial sutures, 2 months versus up to 6 months. However, the eyes tied with horizontal sutures, which showed no induced with-the-rule astigmatism at the time of surgery, showed even more rapid stabilization between 5 days and 1 month from the time of surgery. To get the most rapid visual rehabilitation following cataract surgery, a wound closure which generates no induced with-the-rule cylinder such as horizontal sutures would be required.

  10. Bilateral Small Incision Lenticule Extraction (SMILE) After Penetrating Keratoplasty.

    Science.gov (United States)

    Kim, Bu Ki; Mun, Su Joung; Lee, Dae Gyu; Chung, Young Taek

    2016-08-01

    To report a case of successful bilateral small incision lenticule extraction (SMILE) performed on a patient who had penetrating keratoplasty and astigmatic keratotomy in the right eye and penetrating keratoplasty in the left eye. Case report. Astigmatic keratotomy was used to reduce astigmatism of the right eye because astigmatism was higher than the maximum correction limitation of SMILE. Bilateral SMILE was performed afterward. Although there were no difficulties during lenticule separation and removal of the right eye, wound dehiscence occurred during lenticule separation of the left eye. Two sutures were used at both ends of the incision, and the remainder of the procedure was successfully completed. Visual acuity improved to 20/50 in both eyes without correction, and the corrected distance visual acuities were 20/50 and 20/30 in the right and left eyes, respectively, at the 6-month postoperative visit. SMILE is a potentially effective alternative in correcting refractive errors in patients following penetrating keratoplasty. However, studies with a larger patient population with longer follow-up periods are needed to confirm these initial findings. [J Refract Surg. 2016;32(9):644-647.]. Copyright 2016, SLACK Incorporated.

  11. Long-Term Keratometric Changes after Penetrating Keratoplasty for Keratoconus and Fuchs Endothelial Dystrophy

    Science.gov (United States)

    Raecker, Matthew E.; Erie, Jay C.; Patel, Sanjay V.; Bourne, William M.

    2008-01-01

    Purpose To compare long-term keratometric changes after penetrating keratoplasty (PK) for keratoconus and Fuchs endothelial dystrophy. Methods We retrospectively analyzed 168 corneas after PK for keratoconus (85 eyes of 63 subjects) and Fuchs dystrophy (83 eyes of 60 subjects). Patients were examined after final suture removal at 12 months after PK to 30 years after surgery. Operations were performed by one surgeon using the same suturing technique in all cases. Eyes were excluded from further analysis after regrafting or after relaxing incisions. Mean keratometric corneal power and astigmatism were measured by manual keratometry. Data were assessed by using generalized estimating equation models to determine change over time. Results Mean keratometric corneal power and keratometric astigmatism increased through 30 years after PK for keratoconus (P astigmatism after PK in keratoconus patients differed from the change in Fuchs dystrophy patients only at 10 or more years after PK (P = .002 and P = .003). Conclusions Corneal curvature and regular astigmatism increase progressively after PK for keratoconus but remain stable after PK for Fuchs dystrophy. This keratometric instability after PK for keratoconus may lead to delayed corneal ectasia. PMID:19277234

  12. [The adaptation to contact lenses].

    Science.gov (United States)

    Koos, D; Koos, M J

    1992-01-01

    The indications of contact lens adaptation in optical purpose are widely large, starting, with refractive errors [correction of vices], unilateral and bilateral aphakia, myopia, anisometropia and astigmatism, together with the use of contact lens in esthetic purpose. We have been presented the adaptation techniques, the supervise, and maintenance of contact lens.

  13. [Calculations of mean refraction and variation of refraction using a dioptric space].

    Science.gov (United States)

    Touzeau, O; Costantini, E; Gaujoux, T; Borderie, V; Laroche, L

    2010-11-01

    Polar notations (sphere, cylinder, and axis) of refraction perfectly characterize a single refraction but are not suitable for statistical analysis or graphic representation. While the spherical component of refraction can be easily analyzed by the spherical equivalent, statistical analysis of astigmatism requires non-polar expressions of refraction. Indeed, the cylinder and axis of astigmatism are not independent data. In addition, axis is a directional data including a non-trigonometric cycle. Refraction can be written in a non-polar notation by three rectangular coordinates (x, y, z), which can also represent the spherocylinder by one point in a dioptric space. These three coordinates constitute three independent (orthogonal) variables that correspond to a sphere-equivalent component and a pair of Jackson cross-cylinder components, oriented at 0°/90° (WTR/ATR astigmatism) and 45°/135° (oblique astigmatism). Statistical analysis and graphical representation become less complicated when using rectangular coordinates of refraction. Rectangular coordinates of the mean refraction are obtained by average rectangular coordinates. Similarly, rectangular coordinates of refraction change are obtained by a single subtraction of rectangular coordinates between the final and initial refractions. After statistical analysis, the rectangular coordinates obtained can be converted into a polar form for a more easily understood result. Finally, non-polar notations including rectangular coordinates are useful for statistical and graphical analysis, which would be difficult with only conventional polar notations of refraction. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

  14. 78 FR 14557 - Guidance for Industry and Food and Drug Administration Staff: Investigational Device Exemption...

    Science.gov (United States)

    2013-03-06

    ... vision that is not correctable to normal levels by spectacles, contact lenses, medications, surgery, or... the heading of this document. FOR FURTHER INFORMATION CONTACT: For pre-clinical concerns: ] Ethan D... (myopia, astigmatism, presbyopia). This guidance is intended to assist device manufacturers who plan to...

  15. Intraocular Lens Implantation Surgery In Onitsha, Nigeria | Nwosu ...

    African Journals Online (AJOL)

    Surgical complications were recurrent uveitis, 20 eyes (48.8%) astigmatism, 14 eyes (34.1%); high intraocular pressure, 3 eyes (7.3%); posterior capsule opacity, 3 eyes (7.3%) posterior castle tear, 2 eyes (4.9%). Poor post-operative acuity were due to posterior capsule opacity and macular scar, 3 eyes each; leukoma, ...

  16. Spectacle use after routine cataract surgery.

    Science.gov (United States)

    Wilkins, M R; Allan, B; Rubin, G

    2009-10-01

    To measure spectacle dependence following bilateral monofocal intraocular lens (IOL) implantation and assess how it is predicted by postoperative refraction. 300 cataract patients had bilateral phacoemulsification surgery with monofocal IOL implantation. A spherical equivalent of 0 to -0.5 D was targeted. Three months after surgery, patients answered a questionnaire and had a spectacle refraction. Refractions were converted into vector notation. Logistic regression was used to evaluate whether spectacle dependence for near and distance was related to overall refractive error, spherical error, signed spherical error and astigmatic error. 169 patients attended for assessment. 38 wore distance glasses, and 160 wore reading glasses either some or all of the time. The mean right spherical equivalent was -0.03 D, and the mean right cylinder was -0.64 D. Left outcomes were similar. Patients were 34 times more likely to always use distance glasses per dioptre of astigmatic error in the better eye (p0.15). Similar effects were seen for both the better and worse eyes. Near-spectacle use was not dependent on astigmatic error (odds ratio = 0.22, p>0.12). It was only related to the signed spherical error in the worse eye with hypermetropic patients 6.74 times more likely to always wear spectacles per dioptre of positive spherical error (pspectacle dependence, whereas spherical ammetropia in the range of +/-1.0 D does not. Hypermetropia in the worse eye, but not astigmatism, predicts reading-spectacle dependence.

  17. Refractive errors in patients attending a private hospital in Jos, Nigeria

    African Journals Online (AJOL)

    confirms that most of the refractive error can be corrected with off-the-shelf spectacles. Key words: Anisometropia, astigmatism, hypermetropia, myopia, refractive error. Date of Acceptance: 2-May-2013. Address for correspondence: Dr. Keziah Malu,. Department of Ophthalmology, Benue State University Teaching. Hospital ...

  18. Classical versus complex fractional Fourier transformation.

    Science.gov (United States)

    Dragoman, D

    2009-02-01

    The quantum optical complex fractional Fourier transform (FRFT) has been related to the classical FRFT using both classical and quantum formalisms. In particular, it was shown that the kernel of the complex FRFT can be classically produced with rotated astigmatic optical systems that mimic the quantum entanglement property.

  19. Parameter study for a central-receiver power station

    Energy Technology Data Exchange (ETDEWEB)

    Biggs, F.; Vittitoe, C.N.

    1977-01-01

    The interactions between alignment and focusing strategies and heliostat errors are described and illustrated. Some descriptions of astigmatic aberrations are developed and are used to suggest an evaluation criterion for concentrators. Finally, an analysis of measurements for evaluating heliostat reflectors is given.

  20. HIV and NCDs: inevitable interaction in resource limited settings.

    African Journals Online (AJOL)

    communication for a deaf child, using sign language.24. The child health theme continues with a South African paper on astigmatism,25 followed by one highlighting suicidal ideation among adolescents in Swaziland.26 The section ends with intestinal candidiasis and antibiotics in. Nsukka, Nigeria.27. Health system ...

  1. Material Assessment for ITER’s Collective Thomson Scattering first mirror

    DEFF Research Database (Denmark)

    Santos, R.; Policarpo, H.; Gonçalves, B.

    2015-01-01

    ITER’s Collective Thomson Scattering (CTS) system is a diagnostic instrument that will measure the plasma density and velocity through Thomson scattering of microwave radiation. Some of the key components of the CTS are quasioptical mirrors used to produce astigmatic beam patterns, which have...

  2. Change in corneal curvature induced by surgery

    NARCIS (Netherlands)

    G. van Rij (Gabriel)

    1987-01-01

    textabstractThe first section deals with the mechanisms by which sutures, incisions and intracorneal contact lenses produce a change in corneal curvature. To clarify the mechanisms by which incisions and sutures produce astigmatism, we made incisions and placed sutures in the corneoscleral limbus

  3. Multifocal Toric Intraocular Lens for Traumatic Cataract in a Child

    Directory of Open Access Journals (Sweden)

    Yanfeng Zeng

    2016-10-01

    Full Text Available A child suffering from traumatic cataract and corneal astigmatism of 2.14 D had a phacoemulsification operation and implantation of a ReSTOR Toric intraocular lens (IOL to correct the astigmatism. The primary outcome measurements were the uncorrected distance visual acuity (UDVA, uncorrected near vision at 40 cm, intraocular pressure, spherical equivalent refraction, residual astigmatism, corneal astigmatism, presence of unusual optical phenomena, and use of spectacles. At 7 months postoperatively, UDVA was maintained between 16/20 and 24/20, near vision was between J1 and J3, residual spherical refraction was 0–0.37 D, and residual refractive cylinder was between 0 and 0.67 D. A multifocal toric IOL can provide the possibility of satisfactory vision for both distant and near conditions without the use of spectacles to meet children’s needs when studying and doing sports. Additionally, binocular vision can be reconstructed. This intervention, therefore, seems to be a satisfactory alternative.

  4. Page 1 Page 2 Page 3 Page 4 Page 5 11. 12. institution. J. of ...

    African Journals Online (AJOL)

    ocular lens implantation in Nepal. Ophthalmol. 36. 13. 14. 1999, 106 (10): 1887 – 92. Storr-Paulsen A., Madsen H., Perriad A.: Possible factors modifying the surgically induced astigmatism in cataract surgery. Acta. Ophthalmologica Scandinavica. 1999, 77 (5), 548. – 51. Montan P.G., Koranyi G., Setterquist H. E., Stridh.

  5. Socio-economic background and prevalence of visual defects ...

    African Journals Online (AJOL)

    Finding showed that visual defects viz hyperopia, myopia and astigmatism suffered by students in public and private secondary schools in Calabar Municipality is not dependent on the socioeconomic background of their parents. Furthermore the study revealed that myopia has a prevalence of 41% followed by hyperopia ...

  6. Effect of iris registration on outcomes of LASIK for myopia with the VISX CustomVue platform

    DEFF Research Database (Denmark)

    Moshirfar, Majid; Chen, Michael C; Espandar, Ladan

    2009-01-01

    PURPOSE: To compare visual outcomes after LASIK using the VISX STAR S4 CustomVue, with and without Iris Registration technology. METHODS: In this retrospective study, LASIK was performed on 239 myopic eyes, with or without astigmatism, of 142 patients. Iris registration LASIK was performed on 121...

  7. Page 1 NIGERIAN JOURNAL OF OPHTHALMIOLOGY ...

    African Journals Online (AJOL)

    compound myopia. Appropriate provision should therefore be made to correct this visual problem. Keywords: refractive astigmatism, prevalence, types. INTRODUCTION. Refractive error is the most common visual problem among Nigerian adults." It is a common cause of visual impairmentand eye ache and may even cause ...

  8. The effect of pterygium surgery on contrast sensitivity and corneal topographic changes

    Directory of Open Access Journals (Sweden)

    Joo Youn Oh

    2010-04-01

    Full Text Available Joo Youn Oh, Won Ryang WeeDepartment of Ophthalmology, Seoul National University Hospital, Seoul, KoreaPurpose: To investigate the effect of pterygium surgery on corneal topography and contrast sensitivity.Patient and methods: The IRB approved this prospective, nonrandomized, self-controlled study. Computerized videokeratography (Orbscan II was performed in 36 patients with primary pterygia, both before and 1 month after pterygium excision with limbal-conjunctival autografting. The topographic parameters were compared. Spatial contrast sensitivity testing was performed using VCTS 6500. Differences between preoperative and postoperative values were evaluated statistically.Results: The mean Sim K astigmatism and irregularity index, significantly decreased after pterygium surgery. The mean refractive power significantly increased after the operation. The “with-the-rule” astigmatism induced by pterygium became “against-the-rule” astigmatism after pterygium removal (P = 0.041. The contrast sensitivity of 6, 12, and 18 cycles per degree, significantly increased from 1.55 ± 0.28, 0.97 ± 0.47, and 0.29 ± 0.16 to 1.72 ± 0.18, 1.21 ± 0.44, and 0.65 ± 0.48, respectively (P = 0.007, <0.001, <0.001, respectively.Conclusions: Pterygium surgery significantly reduces corneal topographic astigmatism and improves contrast sensitivity.Keywords: corneal topography, visual acuity

  9. Pinhole Glasses

    Science.gov (United States)

    Colicchia, Giuseppe; Hopf, Martin; Wiesner, Hartmut; Zollman, Dean

    2008-01-01

    Eye aberrations are commonly corrected by lenses that restore vision by altering rays before they pass through the cornea. Some modern promoters claim that pinhole glasses are better than conventional lenses in correcting all kinds of refractive defects such as myopia (nearsighted), hyperopia (farsighted), astigmatisms, and presbyopia. Do pinhole…

  10. The correlation between variation of visual acuity and the anterior chamber depth in the early period after phacoemulsification

    Directory of Open Access Journals (Sweden)

    Kai-jian CHEN

    2011-04-01

    Full Text Available Objective To investigate the correlation between the visual acuity variation and the anterior chamber depth in the early period after phacoemulsification.Methods Thirty-six eyes of 32 patients with age-related cataract underwent 3.2mm clear corneal incision phacoemulsification and intraocular lens(IOL implantation.The visual acuity was examined and horizontal curvature(K1,vertical curvature(K2,corneal astigmatism,and anterior chamber depth were measured with IOL-master preoperatively and also on 1,3,7 and 15 postoperative days.The changes in parameters were compared,and the correlations among visual acuity,corneal astigmatism and anterior chamber depth were analyzed.Results Before operation and 1d,3d,7d and 15d after operation,the corneal astigmatism was-0.87±0.40D,-1.92±1.38D,-1.69±1.13D,-1.45±0.79D and-1.36±0.74D;the anterior chamber depth was 3.08±0.35mm,4.04±0.38mm,4.28±0.29mm,4.22±0.17mm and 4.22±0.16mm;the visual acuity was 0.18±0.10,0.44±0.14,0.59±0.12,0.61±0.11 and 0.62±0.14.Significant difference was found between pre-operative and postoperative visual acuity,corneal astigmatism and anterior chamber depth,and it was also found in corneal astigmatism between 1d and 15d post operation(P < 0.05,as well as in anterior chamber depth and visual acuity between 1d and 3d post operation(P < 0.05.A positive correlation was found between visual acuity and corneal astigmatism on 1d(r=0.42,P < 0.05,3d(r=0.35,P < 0.05 and 7d(r=0.35,P < 0.05 post operation;and a negative correlation was found between visual acuity and anterior chamber depth on 3d(r=-0.29,P < 0.05,7d(r=-0.43,P < 0.01 and 15d(r=-0.37,P < 0.05 post operation.Conclusion Both the corneal astigmatism and the anterior chamber depth are correlated with the visual acuity variation in the early period after phacoemulsification.

  11. Comparative analysis of the visual performance after implantation of the toric implantable collamer lens in stable keratoconus: a 4-year follow-up after sequential procedure (CXL+TICL implantation).

    Science.gov (United States)

    Doroodgar, Farideh; Niazi, Feazollah; Sanginabadi, Azad; Niazi, Sana; Baradaran-Rafii, Alireza; Alinia, Cyrus; Azargashb, Eznollah; Ghoreishi, Mohammad

    2017-01-01

    To report on 4-year postoperative visual performance with the toric implantable collamer lens (TICL) for stable keratoconus after sequential procedure (corneal collagen crosslinking plus TICL implantation). Forty eyes of 24 patients with stable keratoconus with myopia between 0.00 and -18.00 dioptres (D) and astigmatism between 1.25 and 8.00 D were evaluated in this prospective interventional study (https://clinicaltrials.gov/ct2/show/NCT02833649). We evaluated refraction, visual outcomes, astigmatic changes analysed by Alpins vector, contrast sensitivity, aberrometry, modulation transfer functions (MTFs), defocus curve, and operative and postoperative complications. At 4-year follow-up, 45% had 20/20 vision or better and 100% had 20/40 or better uncorrected visual acuity (UCVA). Vector analysis of refractive astigmatism shows that the surgically induced astigmatism (SIA) (3.20±1.46 D) was not significantly different from the target induced astigmatism (TIA) (3.14±1.42 D) (p=0.620). At 4 years postoperatively, none of the eyes showed a decrease in UCVA, in contrast to 24 eyes in which UCVA was increased by ≥1 lines, with contrast sensitivity and improvement in total aberrations and MTF value at 5 per degree (*p=0.004) after TICL implantation. The cumulative 4-year corneal endothelial cell loss was ≤5%. No patients reported dissatisfaction. At the end of follow-up, the vault was 658±54.33m (range, 500-711) and the intraocular pressure was 11.7±2.08 mm Hg. Occurrences of glare and night-driving troubles diminished after TICL surgery. The results from this standardised clinical investigation support TICL implantation from clinical and optical viewpoints in patients with stable keratoconus. NCT02833649, Pre-results.

  12. Visual Rehabilitation After Penetrating Keratoplasty.

    Science.gov (United States)

    Asena, Leyla; Altınörs, Dilek D

    2016-11-01

    Here, our aim was to report our treatment strategies and their results performed for visual rehabilitation after penetrating keratoplasty. The medical records of 98 patients (54 male/44 female), with results from 104 eyes, who underwent penetrating keratoplasty between January 2013 and January 2015 at the Baskent University Faculty of Medicine, Department of Ophthalmology were reviewed. Patient age, indication for penetrating keratoplasty, interventions performed for visual rehabilitation, follow-up duration, topographic and refractive astigmatism at the end of follow-up, and final best corrected visual acuity results were recorded. Mean age of patients was 54 ± 23 years. Indications for penetrating keratoplasty included keratoconus, Fuchs endothelial dystrophy, pseudophakic bullous keratopathy, and corneal scarring. The mean duration of follow-up was 23 ± 11.5 months. Topography-guided suture adjustment and selective suture removal were performed 2 to 6 weeks and after 3 months in eyes with more than 3 diopters of corneal astigmatism in patients who had continuous and interrupted sutures. Spectacle correction was administered for 86 eyes (83%), and contact lenses including rigid gas-permeable and scleral lenses were fitted in 18 eyes (17%) in patients who were unsatisfied with spectacle correction. Relaxing corneal incisions were performed in 23 eyes (22%), and toric intraocular lens implantations were performed in 34 eyes (33%) with cataracts. The mean topographic and absolute refractive astigmatism at the end of follow-up was 3.4 ± 2.6 and 3.6 ± 1.9 diopters. Topography-guided suture adjustment and selective suture removal are effective for minimizing early postoperative astigmatism. If significant astigmatism remains after suture removal, which cannot be corrected by optical means, then further surgical procedures including relaxing incisions and toric intraocular lens implantation can be performed.

  13. Comparison of femtosecond laser-assisted keratoplasty versus conventional penetrating keratoplasty.

    Science.gov (United States)

    Chamberlain, Winston D; Rush, Sloan W; Mathers, William D; Cabezas, Mauricio; Fraunfelder, Frederick W

    2011-03-01

    To compare postoperative outcomes for femtosecond laser-assisted keratoplasty (FLAK) with conventional penetrating keratoplasty (PK). Retrospective, comparative surgical series. Fifty consecutive patients who underwent FLAK and 50 case-controlled patients that had PK at the Casey Eye Institute (Oregon Health & Science University, Portland, OR). Data was collected for 50 consecutive cases that underwent zigzag incision FLAK and was compared with 50 subjects that had conventional blade trephine incision PK with similar age, diagnosis and concurrent ocular morbidities over a 2-year follow-up period. Topographic astigmatism, best spectacle-corrected visual acuity, uncorrected visual acuity, pinhole visual acuity, and the timing of selective suture removal (or adjustment) over various follow-up intervals up to 2 years postoperatively. Significantly lower topographic astigmatism was achieved in the FLAK group over the PK group in the 4- to 6-month follow-up period (P = 0.0324), which correlated well with significant earlier selective suture removal that occurred in that same group over both the 2- to 3-month (P = 0.0025) and 4- to 6-month (P = 0.0236) follow-up periods. This difference in astigmatism was no longer present at any other follow-up period up to 24 months postoperatively. The subset analysis of patients with keratoconus or post-LASIK ectasia did not show any difference in either astigmatism or visual acuity at any time. Compared with PKP, FLAK had significant improvement in astigmatism before but not after the 6 month postoperative follow-up period. Earlier suture removal was noted in the FLAK group. No significant improvement in best spectacle-corrected visual acuity was noted at any time point. There were no complications or difficulties with trephination in the FLAK procedure across a wide range of corneal pathologies. Copyright © 2011 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  14. The effects of chalazion excision on corneal surface aberrations.

    Science.gov (United States)

    Park, Young Min; Lee, Jong Soo

    2014-10-01

    This study is the first to consider the effects of chalazion on corneal surface aberrations taking into account of corneal zones, and to establish the size standard for the excision of chalazion. Twenty three eyes from 23 patients with central upper eyelid chalazion larger than 3mm were recruited in this prospective study. The participants were classified into two groups, depending on size of the lesion: Group 1 with lesion size 3-5mm and Group 2 with lesion size >5mm Chalazion was excised by standard transconjunctival vertical incision. Corneal surface aberrations were measured using a Galilei™ analyzer and an auto-refractometer before and 2 months after the excision. Corneal astigmatism in all patients decreased significantly in both auto refractometer (P=0.012) and Galilei™ (P=0.020) measurements after chalazion excision. RMS of total HOAs decreased significantly in 6mm (P=0.043) and 3mm zone (P=0.051). The RMS of Zernike orders in the vertical and horizontal trefoil decreased significantly in 6mm (P=0.035) and 3mm (P=0.041) zone. Group 2 showed a significant decrease in corneal astigmatism in both auto refractometer (P=0.040) and Galilei™ (P=0.017) parameters after chalazion excision. Group 1 showed an insignificant decrease in corneal astigmatism. Unlike Group 1, the RMS of total HOAs and vertical and horizontal trefoil in 6mm zone decreased significantly in Group 2 (Pchalazion increases astigmatism and HOAs, especially at the peripheral cornea. Significantly induced astigmatism and HOAs are caused by chalazion >5mm in size. Thus, we recommend the surgical excision of chalazion >5mm in size to reduce corneal surface aberrations. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  15. Topography-modified refraction (TMR): adjustment of treated cylinder amount and axis to the topography versus standard clinical refraction in myopic topography-guided LASIK.

    Science.gov (United States)

    Kanellopoulos, Anastasios John

    2016-01-01

    To evaluate the safety, efficacy, and contralateral eye comparison of topography-guided myopic LASIK with two different refraction treatment strategies. Private clinical ophthalmology practice. A total of 100 eyes (50 patients) in consecutive cases of myopic topography-guided LASIK procedures with the same refractive platform (FS200 femtosecond and EX500 excimer lasers) were randomized for treatment as follows: one eye with the standard clinical refraction (group A) and the contralateral eye with the topographic astigmatic power and axis (topography-modified treatment refraction; group B). All cases were evaluated pre- and post-operatively for the following parameters: refractive error, best corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), topography (Placido-disk based) and tomography (Scheimpflug-image based), wavefront analysis, pupillometry, and contrast sensitivity. Follow-up visits were conducted for at least 12 months. Mean refractive error was -5.5 D of myopia and -1.75 D of astigmatism. In group A versus group B, respectively, the average UDVA improved from 20/200 to 20/20 versus 20/16; post-operative CDVA was 20/20 and 20/13.5; 1 line of vision gained was 27.8% and 55.6%; and 2 lines of vision gained was 5.6% and 11.1%. In group A, 27.8% of eyes had over -0.50 diopters of residual refractive astigmatism, in comparison to 11.7% in group B ( P refractive astigmatism of more than -0.5 diopters. Topography-modified refraction (TMR): topographic adjustment of the amount and axis of astigmatism treated, when different from the clinical refraction, may offer superior outcomes in topography-guided myopic LASIK. These findings may change the current clinical paradigm of the optimal subjective refraction utilized in laser vision correction.

  16. Comparison of penetrating keratoplasty performed with a femtosecond laser zig-zag incision versus conventional blade trephination.

    Science.gov (United States)

    Farid, Marjan; Steinert, Roger F; Gaster, Ronald N; Chamberlain, Winston; Lin, Amy

    2009-09-01

    To evaluate visual outcomes and astigmatism in patients who underwent penetrating keratoplasty (PK) with 2 different incision techniques. Retrospective comparison of a consecutive surgical series. Fifty-seven consecutive patients who underwent PK at the University of California, Irvine, academic referral practice. A comparison of 49 eyes of 43 patients that underwent femtosecond laser zig-zag incision pattern PK versus 17 eyes of 14 patients that underwent conventional Barron suction trephination PK performed contemporaneously. All PKs were closed with an identical, 24-bite running nylon suture technique. Topographically determined astigmatism, best spectacle-corrected visual acuity (BSCVA), and recovery of full visual potential. The postoperative follow-up ranged from 1 to 12 months. There was a significant difference in average astigmatism between the groups at postoperative month 1 (P = 0.013) and 3 (P = 0.018). By month 3, the average astigmatism was 3 diopters (D) in the zig-zag group and 4.46 D in the conventional group. Of the patients with normal macular and optic nerve function (n(ZZ) = 32; n(con) = 14), a significant difference in BSCVA was seen at month 1 (P = 0.0003) and month 3 (P = 0.006) with 81% of the zig-zag group versus 45% of the conventional group achieving BSCVA of > or =20/40 by month 3 (P = 0.03). The femtosecond laser generated zig-zag-shaped incision results in a more rapid recovery of BSCVA and induces less astigmatism compared with conventional blade trephination PK. Proprietary commercial disclosure may be found after the references.

  17. Refractive cylinder outcomes after calculating toric intraocular lens cylinder power using total corneal refractive power

    Directory of Open Access Journals (Sweden)

    Davison JA

    2015-08-01

    Full Text Available James A Davison,1 Richard Potvin21Wolfe Eye Clinic, Marshalltown, IA, USA; 2Science in Vision, Akron, NY, USAPurpose: To determine whether the total corneal refractive power (TCRP value, which is based on measurement of both anterior and posterior corneal astigmatism, is effective for toric intraocular lens (IOL calculation with AcrySof® Toric IOLsPatients and methods: A consecutive series of cataract surgery cases with AcrySof toric IOL implantation was studied retrospectively. The IOLMaster® was used for calculation of IOL sphere, the Pentacam® TCRP 3.0 mm apex/ring value was used as the keratometry input to the AcrySof Toric IOL Calculator and the VERION™ Digital Marker for surgical orientation. The keratometry readings from the VERION reference unit were recorded but not used in the actual calculation. Vector differences between expected and actual residual refractive cylinder were calculated and compared to simulated vector errors using the collected VERION keratometry data.Results: In total, 83 eyes of 56 patients were analyzed. Residual refractive cylinder was 0.25 D or lower in 58% of eyes and 0.5 D or lower in 80% of eyes. The TCRP-based calculation resulted in a statistically significantly lower vector error (P<0.01 and significantly more eyes with a vector error ≤0.5 D relative to the VERION-based calculation (P=0.02. The TCRP and VERION keratometry readings suggested a different IOL toric power in 53/83 eyes. In these 53 eyes the TCRP vector error was lower in 28 cases, the VERION error was lower in five cases, and the error was equal in 20 cases. When the anterior cornea had with-the-rule astigmatism, the VERION was more likely to suggest a higher toric power and when the anterior cornea had against-the-rule astigmatism, the VERION was less likely to suggest a higher toric power.Conclusion: Using the TCRP keratometry measurement in the AcrySof toric calculator may improve overall postoperative refractive results

  18. CHARACTERISTIC OF PATIENTS WITH REFRACTIVE DISORDER AT EYE CLINIC OF SANGLAH GENERAL HOSPITAL DENPASAR, BALI-INDONESIA

    Directory of Open Access Journals (Sweden)

    T Handayani-Ariestanti

    2012-09-01

    Full Text Available Objective: Refractive disorders are one of the most common causes of visual impairment worldwide and become the second leading cause of blindness that can be cured. This study aims to know the characteristic of refractive errors patients in Sanglah General Hospital in the period of 1st January until 31st December 2011.Method: This is a retrospective analytical descriptive study. Data were collected retrospectively from patient’s medical records with refractive errors and shown as frequency andpercentage. Visual acuity before and after corrections were investigated and analyzed using McNemar Test.Results: from 579 patients, the most common diagnosis was astigmatism (40.1%, 63% were woman, 39.7% were older than 40 years old, and 60.2% live in Denpasar. In myopia cases, 69.7% patients were woman and 25.1% were between 11-20 years old. In astigmatism cases, 63.4% were woman, 57% were older than 40 years old. Of the hypermetropic cases, 61,3% were woman, 79.5% were older than 40 years. Among presbyopia cases, 53.2% patients were woman with 84.4% were older than 40 years. In McNemar test, there were a significant difference between visual acuity before and after correction in both eyes (p=0.0001. Most astigmatism was with the rule cases on both eyes. On the right eye 54.3% shows mild astigmatism, whereas on the left eye 50.8% shows moderate astigmatism. In hypermetropic cases 92.4% are mild degrees. While 55.5% presbyopic patients needadditional glasses of +1.00 D up to +2.00 D. About 97.9% patients with refractive error were given glasses prescription. Conclusion: mostly refractive errors patient are woman and the most common diagnosis is astigmatism. There were significant differences of visual acuity before and aftercorrection on both eyes (p=0.001.

  19. Criteria for correction of quadratic field-dependent aberrations.

    Science.gov (United States)

    Zhao, Chunyu; Burge, James H

    2002-11-01

    Aberrations of imaging systems can be described by using a polynomial expansion of the dependence on field position, or the off-axis distance of a point object. On-axis, or zero-order, aberrations can be calculated directly. It is well-known that aberrations with linear field dependence can be calculated and controlled by using the Abbe sine condition, which evaluates only on-axis behavior. We present a new set of relationships that fully describe the aberrations that depend on the second power of the field. A simple set of equations is derived by using Hamilton's characteristic functions and simplified by evaluating astigmatism in the pupil. The equations, which we call the pupil astigmatism criteria, use on-axis behavior to evaluate and control all aberrations with quadratic dependence on the field and arbitrary dependence on the pupil. These relations are explained and are validated by using several specific optical designs.

  20. Prospects for electron beam aberration correction using sculpted phase masks.

    Science.gov (United States)

    Shiloh, Roy; Remez, Roei; Arie, Ady

    2016-04-01

    Technological advances in fabrication methods allowed the microscopy community to take incremental steps towards perfecting the electron microscope, and magnetic lens design in particular. Still, state of the art aberration-corrected microscopes are yet 20-30 times shy of the theoretical electron diffraction limit. Moreover, these microscopes consume significant physical space and are very expensive. Here, we show how a thin, sculpted membrane is used as a phase-mask to induce specific aberrations into an electron beam probe in a standard high resolution TEM. In particular, we experimentally demonstrate beam splitting, two-fold astigmatism, three-fold astigmatism, and spherical aberration. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Optical path length and trajectory stability in rotationally asymmetric multipass cells.

    Science.gov (United States)

    Harden, Galen H; Cortes-Herrera, Luis E; Hoffman, Anthony J

    2016-08-22

    We describe the behavior of optical trajectories in multipass rotationally asymmetric cavities (RACs) using a phase-space motivated approach. Emphasis is placed on generating long optical paths. A trajectory with an optical path length of 18 m is generated within a 68 cm3 volume. This path length to volume ratio (26.6 cm-2) is large compared to current state of the art multipass cells such as the cylindrical multipass cell (6.6 cm-2) and astigmatic Herriott cell (9 cm-2). Additionally, the effect of small changes to the input conditions on the path length is studied and compared to the astigmatic Herriott cell. This work simplifies the process of designing RACs with long optical path lengths and could lead to broader implementation of these multipass cells.

  2. Fitting gas-permeable contact lenses after penetrating keratoplasty.

    Science.gov (United States)

    Genvert, G I; Cohen, E J; Arentsen, J J; Laibson, P R

    1985-05-15

    Between Sept. 1, 1981, and Jan. 31, 1984, 74 eyes (70 patients) were fitted with gas-permeable Polycon contact lenses and monitored for at least six months (range, six to 33 months; mean, 14 months). The major indications for hard contact lens fitting were astigmatism and anisometropia. Astigmatism in this series ranged from 0 to 17.50 diopters (mean, 7.7 diopters). Most patients achieved visual acuities of 20/40 or better (67 of 74, 90%) with contact lenses. Contact lenses were discontinued in 18% (13 of 74), because of graft rejection in four cases and because of contact lens intolerance in nine cases. Our results demonstrated that gas-permeable hard lenses can be fitted successfully in most patients unable to achieve optimal vision with spectacle correction after penetrating keratoplasty.

  3. Deep anterior lamellar keratoplasty for the management of iatrogenic keratectasia occurring after hexagonal keratotomy

    Directory of Open Access Journals (Sweden)

    Paras Mehta

    2012-01-01

    Full Text Available Iatrogenic keratectasia has been reported subsequent to refractive surgery or trauma. Hexagonal keratotomy (HK is a surgical incisional technique to correct hyperopia. A number of complications have been reported following this procedure, including irregular astigmatism, wound healing abnormalities and corneal ectasia. When visual acuity is poor because of ectasia or irregular astigmatism and contact lens fitting is not possible, penetrating or lamellar keratoplasty can be performed. Since incisions in refractive keratotomy are set at 90-95% depth of cornea, intraoperative microperforations are known to occur and lamellar keratoplasty may become difficult. We describe deep anterior lamellar keratoplasty (DALK used to successfully manage keratectasia after HK. Pre DALK vision was 20/400 and post DALK vision was 20/30 two months after surgery. This report aims to show improved visual outcome in corneal ectasia secondary to HK. DALK can be a procedure of choice with proper case selection.

  4. Inner-product spaces for quantitative analysis of eyes and other optical systems

    Directory of Open Access Journals (Sweden)

    William F. Harris

    2016-03-01

    Full Text Available Because dioptric power matrices of thin systems constitute a (three-dimensional inner-product space, it is possible to define distances and angles in the space and so do quantitative analyses on dioptric power for thin systems. That includes astigmatic corneal powers and refractive errors. The purpose of this study is to generalise to thick systems. The paper begins with the ray transference of a system. Two 10-dimensional inner-product spaces are devised for the holistic quantitative analysis of the linear optical character of optical systems. One is based on the point characteristic and the other on the angle characteristic; the first has distances with the physical dimension L−1 and the second has the physical dimension L. A numerical example calculates the locations, distances from the origin and angles subtended at the origin in the 10-dimensional space for two arbitrary astigmatic eyes.

  5. Imaging with spherically bent crystals or reflectors

    Science.gov (United States)

    Bitter, M.; Delgado Aparicio, L. F.; Hill, K. W.; Scott, S.; Ince-Cushman, A.; Reinke, M.; Podpaly, Y.; Rice, J. E.; Beiersdorfer, P.; Wang, E.

    2010-07-01

    This paper consists of two parts: part I describes the working principle of a recently developed x-ray imaging crystal spectrometer, where the astigmatism of spherically bent crystals is being used with advantage to record spatially resolved spectra of highly charged ions for Doppler measurements of the ion-temperature and toroidal plasma-rotation-velocity profiles in tokamak plasmas. This type of spectrometer was thoroughly tested on NSTX and Alcator C-Mod, and its concept was recently adopted for the design of the ITER crystal spectrometers. Part II describes imaging schemes, where the astigmatism has been eliminated by the use of matched pairs of spherically bent crystals or reflectors. These imaging schemes are applicable over a wide range of the electromagnetic radiation, which includes microwaves, visible light, EUV radiation and x-rays. Potential applications with EUV radiation and x-rays are the diagnosis of laser-produced plasmas, imaging of biological samples with synchrotron radiation and lithography.

  6. Topography-guided custom ablation treatment for treatment of keratoconus

    Directory of Open Access Journals (Sweden)

    Rohit Shetty

    2013-01-01

    Full Text Available Keratoconus is a progressive ectatic disorder of the cornea which often presents with fluctuating refraction and high irregular astigmatism. Correcting the vision of these patients is often a challenge because glasses are unable to correct the irregular astigmatism and regular contact lenses may not fit them very well. Topography-guided custom ablation treatment (T-CAT is a procedure of limited ablation of the cornea using excimer laser with the aim of regularizing the cornea, improving the quality of vision and possibly contact lens fit. The aim of the procedure is not to give a complete refractive correction. It has been tried with a lot of success by various groups of refractive surgeons around the world but a meticulous and methodical planning of the procedure is essential to ensure optimum results. In this paper, we attempt to elucidate the planning for a T-CAT procedure for various types of cones and asphericities.

  7. New Refractive Surgery Procedures and Their Implications for Aviation Safety

    Science.gov (United States)

    2006-04-01

    visual performance in dim illumination (167,225), dry eyes (136,226,227), irregular astigmatism (226), and dislodged or detached corneal flap due to...vision when illumination varies; 307,308) . As with all types of surgery, there is the possibility of complications, which include loss of endothelial...headlights, and/or streetlights ) before and after LASIK . There was an overall improvement in nighttime visual function and night driving (337

  8. Comparison of the femtosecond laser and mechanical microkeratome for flap cutting in LASIK

    OpenAIRE

    Li-Kun Xia; Jie Yu; Guang-Rui Chai; Dang Wang; Yang Li

    2015-01-01

    AIM: To compare refractive results, higher-order aberrations (HOAs), contrast sensitivity and dry eye after laser in situ keratomileusis (LASIK) performed with a femtosecond laser versus a mechanical microkeratome for myopia and astigmatism.METHODS: In this prospective, non-randomized study, 120 eyes with myopia received a LASIK surgery with the VisuMax femtosecond laser for flap cutting, and 120 eyes received a conventional LASIK surgery with a mechanical microkeratome. Flap thickness, visua...

  9. Corrective Techniques and Future Directions for Treatment of Residual Refractive Error Following Cataract Surgery

    OpenAIRE

    Moshirfar, Majid; McCaughey, Michael V.; Santiago-Caban, Luis

    2014-01-01

    Postoperative residual refractive error following cataract surgery is not an uncommon occurrence for a large proportion of modern-day patients. Residual refractive errors can be broadly classified into 3 main categories: myopic, hyperopic, and astigmatic. The degree to which a residual refractive error adversely affects a patient is dependent on the magnitude of the error, as well as the specific type of intraocular lens the patient possesses. There are a variety of strategies for resolving r...

  10. Laser corneal refractive surgery in the twenty-first century: a review of the impact of refractive surgery on high-order aberrations (and vice versa)

    Science.gov (United States)

    Arba-Mosquera, Samuel; Arbelaez, Maria C.; de Ortueta, Diego

    2010-07-01

    Here we review the situation of laser corneal refractive surgery in the twenty-first century. We pay special attention to the change in aberrations, covering the compensation of the loss of ablation efficiency at non-normal incidence, the effects of cyclotorsional errors, aspheric, wavefront optimized and aberration neutral concepts, and centration of refractive profiles. A review of the clinical outcomes is provided including myopic, hyperopic, and astigmatic, as well as wavefront customized or presbyopic outcomes.

  11. Laser in situ keratomileusis in adult patients with anisometropic amblyopia

    Directory of Open Access Journals (Sweden)

    Dilek Yaşa

    2013-06-01

    Full Text Available AIM: To evaluate the increase in corrected distance visual acuity (CDVA after laser in situ keratomileusis (LASIK in adults with anisometropic amblyopia.METHODS: The medical records of consecutive patients diagnosed with anisometropic amblyopia at the time of refractive evaluation who underwent LASIK were retrospectively reviewed. Patients with at least a two-line difference of visual acuity (VA between the eyes with a spherical refractive error difference of at least 3.00 diopters (D or an astigmatic difference of at least 2.00D were included. Patients with any other possible reason for amblyopia other than anisometropia or those who had undergone previous amblyopia treatment were excluded. Amblyopic eyes with myopia or myopic astigmatism were considered as group 1, hypermetropia or hypermetropic astigmatism constituted group 2, and mixed astigmatism patients comprised group 3. Uncorrected distance visual acuity (UDVA, subjective manifest refraction, and CDVA were analyzed at 1 week and 1 month, 3, and 6 months. RESULTS: The study included 57 eyes of 57 patients. There were 33 eyes in group 1, 12 eyes in group 2, and 12 eyes in group 3. The preoperative mean values for spherical equivalent of subjective manifest refraction (SE in groups 1, 2, and 3 were (-4.66±1.97D, (4.40±1.00D, and (0.15±1.05D, respectively. Mean CDVA improved 0.1 log units (1 line LogMAR at 6 months (P0.05. Moreover, age, the amount of preoperative refractive error, and the levels of preoperative corrected and UDVA had no effect on postoperative CDVA improvement (P>0.05.CONCLUSION: Correction of refractive errors with LASIK produced significant CDVA improvement in adult patients with anisometropic amblyopia and no previous amblyopia treatment.

  12. Refração por retinoscopia com luz em faixa em cães Refraction by streak retinoscopy in dogs

    Directory of Open Access Journals (Sweden)

    J.J.T. Ranzani

    2008-04-01

    Full Text Available A refração ocular por retinoscopia com luz em faixa em 10 cães normais, sem raça definida, demonstrou que a maioria dos animais, independentemente do porte, apresentou tendência à hipermetropia, além de anisometropia e astigmatismo.Ocular refraction by streak retinoscopy performed in 10 mixed breed dogs showed that most of the animals, independently of size, had a tendency to hypermetropia, anisometropia, and astigmatism.

  13. Comparison of perceptual eye positions among patients with different degrees of anisometropia

    OpenAIRE

    Yang, Cheng; Li, Xue; Zhang, Guanrong; Lan, Jianqing; Zhang, Yan; Chu, Hang; Li, Juan; Xie, Wenjuan; Wang, Shujun; Yan, Li; Zeng, Jin

    2017-01-01

    Abstract The aim of this study is to compare the perceptual eye positions (PEPs) among patients with different degrees of anisometropia. A total of 157 patients were recruited into this retrospective study. A detailed ophthalmic examination was conducted on each patient. The degree of refractive errors in the presence of astigmatism was converted into the degree of spherical equivalent (SE). Patients were divided into 3 groups according to the interocular SE difference: severe anisometropia g...

  14. Is Noncycloplegic Photorefraction Applicable for Screening Refractive Amblyopia Risk Factors?

    Directory of Open Access Journals (Sweden)

    Zhale Rajavi

    2012-01-01

    Full Text Available Purpose: To compare the accuracy of noncycloplegic photorefraction (NCP with that of cycloplegic refraction (CR for detecting refractive amblyopia risk factors (RARFs and to determine cutoff points. Methods: In this diagnostic test study, right eyes of 185 children (aged 1 to 14 years first underwent NCP using the PlusoptiX SO4 photoscreener followed by CR. Based on CR results, hyperopia (≥ +3.5 D, myopia (≥ -3 D, astigmatism (≥ 1.5 D, and anisometropia (≥ 1.5 D were set as diagnostic criteria based on AAPOS guidelines. The difference in the detection of RARFs by the two methods was the main outcome measure. Results: RARFs were present in 57 (30.8% and 52 (28.1% of cases by CR and NCP, respectively, with an 89.7% agreement. In contrast to myopia and astigmatism, mean spherical power in hyperopic eyes was significantly different based on the two methods (P < 0.001, being higher with CR (+5.96 ± 2.13 D as compared to NCP (+2.37 ± 1.36 D. Considering CR as the gold standard, specificities for NCP exceeded 93% and sensitivities were also acceptable (≥ 83% for myopia and astigmatism. Nevertheless, sensitivity of NCP for detecting hyperopia was only 45.4%. Using a cutoff point of +1.87 D, instead of +3.5 D, for hyperopia, sensitivity of NCP was increased to 81.8% with specificity of 84%. Conclusion: NCP is a relatively accurate method for detecting RARFs in myopia and astigmatism. Using an alternative cutoff point in this study, NCP may be considered an acceptable device for detecting hyperopia as well.

  15. Suction loss during femtosecond laser-assisted small-incision lenticule extraction: Incidence and analysis of risk factors.

    Science.gov (United States)

    Osman, Ihab M; Awad, Ramy; Shi, Wei; Abou Shousha, Mohamed

    2016-02-01

    To determine the incidence of and analyze risk factors for suction loss during femtosecond laser-assisted small incision lenticule extraction in the management of myopia or myopic astigmatism. Roayah Vision Correction Center, Alexandria, Egypt. Retrospective comparative case-control study. All eyes that had femtosecond laser-assisted small-incision lenticule extraction for the correction of myopia and myopic astigmatism performed between August 2010 and April 2014 were included. Eyes that developed suction loss were identified. Their characteristics, including demographic data (age and sex), eye laterality, manifest refraction, flat keratometry (K) reading, steep K reading, K astigmatism, optical zone, central corneal thickness, and corneal cap diameter and thickness, were compared with those in randomly selected control eyes to determine the risk factors for developing suction loss. Of the 3376 eyes that had femtosecond laser-assisted small-incision lenticule extraction during the study, 70 (2.1%) developed loss of suction. The incidence decreased with surgical experience (5.06% in 2010, 3.59% in 2011, 3.41% in 2012, 2.32% in 2013, and 1.84% in 2014), suggesting a learning curve. A multivariate logistic regression model showed that eyes with a larger cap diameter were significantly more likely to develop suction loss (P = .023; odds ratio, 9.60). Surgical experience significantly decreased the risk for suction loss during femtosecond laser-assisted small incision lenticule extraction for the correction of myopia or myopic astigmatism but did not eliminate it. A larger cap diameter significantly increased the risk for developing the suction loss. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  16. Risk Factors for Amblyopia in the Vision In Preschoolers Study

    Science.gov (United States)

    Pascual, Maisie; Huang, Jiayan; Maguire, Maureen G; Kulp, Marjean Taylor; Quinn, Graham E; Ciner, Elise; Cyert, Lynn A; Orel-Bixler, Deborah; Moore, Bruce; Ying, Gui-shuang

    2013-01-01

    Objective To evaluate risk factors for unilateral amblyopia and for bilateral amblyopia in the Vision In Preschoolers (VIP) Study. Design Multicenter, cross-sectional Study. Participants Three- to 5-year old Head Start preschoolers from 5 clinical centers, over-representing children with vision disorders. Methods All children underwent comprehensive eye exams including threshold visual acuity (VA), cover testing, and cycloplegic retinoscopy, performed by VIP-certified optometrists and ophthalmologists who were experienced in providing care to children. Monocular threshold VA was tested using single-surround HOTV letter protocol without correction, and retested with full cycloplegic correction when retest criteria were met. Unilateral amblyopia was defined as an inter-ocular difference in best-corrected VA ≥2 lines. Bilateral amblyopia was defined as best-corrected VA in each eye worse than 20/50 for 3-year-olds and worse than 20/40 for 4- to 5-year-olds. Main Outcome Measures Risk of amblyopia was summarized by The odds ratios (ORs) and their 95% confidence intervals (95% CIs) estimated from logistic regression models. Results In this enriched sample of Head Start children (N=3869), 296 (7.7%) children had unilateral amblyopia, and 144 (3.7%) children had bilateral amblyopia. Presence of strabismus (pamblyopia. Presence of strabismus, hyperopia ≥2.0 D, astigmatism ≥1.0 D, or anisometropia ≥0.5 D were present in 91% of children with unilateral amblyopia. Greater magnitude of astigmatism (pamblyopia. Bilateral hyperopia ≥3.0 diopters (D) or astigmatism ≥1.0 D were present in 76% of children with bilateral amblyopia. Conclusion Strabismus and significant refractive errors were risk factors for unilateral amblyopia. Bilateral astigmatism and bilateral hyperopia were risk factors for bilateral amblyopia. Despite differences in selection of study population, these results validated the findings from the Multi-ethnic Pediatric Eye Disease Study and Baltimore

  17. Corneal Donor Tissue Preparation for Endothelial Keratoplasty

    OpenAIRE

    Woodward, Maria A.; Titus, Michael; Mavin, Kyle; Shtein, Roni M.

    2012-01-01

    Over the past ten years, corneal transplantation surgical techniques have undergone revolutionary changes1,2. Since its inception, traditional full thickness corneal transplantation has been the treatment to restore sight in those limited by corneal disease. Some disadvantages to this approach include a high degree of post-operative astigmatism, lack of predictable refractive outcome, and disturbance to the ocular surface. The development of Descemet's stripping endothelial keratoplasty (DSEK...

  18. Six-month clinical outcomes after hyperopic correction with the SCHWIND AMARIS Total-Tech laser

    Science.gov (United States)

    Arbelaez, María Clara; Vidal, Camila; Arba Mosquera, Samuel

    2011-01-01

    Purpose To evaluate postoperative clinical outcomes, and corneal High Order Aberrations, among eyes with hyperopia up to +5 D of spherical equivalent, that have undergone LASIK treatments using the SCHWIND AMARIS laser system. Methods At six-month follow-up, 100 eyes with preoperative hyperopia or hyperopic astigmatism up to +5 D of spherical equivalent were retrospectively analysed. Standard examinations, pre- and postoperative wavefront analysis with a corneal-wavefront-analyzer (OPTIKON Scout) were performed. Aberration-Free aspheric treatments were planned with Custom Ablation Manager software and ablations performed using the SCHWIND AMARIS flying-spot excimer laser system (both SCHWIND eye-tech-solutions). LASIK flaps were created using a LDV femtosecond laser (Ziemer Group) in all cases. Clinical outcomes were evaluated in terms of predictability, refractive outcome, safety, and wavefront aberration. Results At six month, 90 % of eyes achieved ≥ 20/25 UCVA and 44 % achieved ≥ 20/16 UCVA. Seventy-four percent of eyes were within ± 0.25D of spherical equivalent and 89 % within ± 0.50D, with 94 % within 0.50D of astigmatism. Mean spherical equivalent was −0.12 ± 0.51D and 0.50 ± 0.51D for the astigmatism. Fifty-two percent of eyes improved BSCVA vs. only 19 % losing lines of BSCVA. Predictability slope for refraction was 1.03 and intercept +0.01 D. On average, negative corneal spherical aberrations were significantly increased by the treatments, no other aberration terms changed from pre- to postoperative values. Conclusions LASIK for hyperopia and hyperopic astigmatism with SCHWIND AMARIS yields very satisfactory visual outcomes. Preoperative refractions were postoperatively reduced to subclinical values with no clinically relevant induction of corneal HOA.

  19. Refractive errors, visual impairment, and the use of low-vision devices in albinism in Malawi.

    Science.gov (United States)

    Schulze Schwering, M; Kumar, N; Bohrmann, D; Msukwa, G; Kalua, K; Kayange, P; Spitzer, M S

    2015-04-01

    This study focuses on the refractive implications of albinism in Malawi, which is mostly associated with the burden of visual impairment. The main goal was to describe the refractive errors and to analyze whether patients with albinism in Malawi, Sub-Saharan Africa, benefit from refraction. Age, sex, refractive data, uncorrected and best-corrected visual acuity (UCVA, BCVA), colour vision, contrast sensitivity, and the prescription of sunglasses and low vision devices were collected for a group of 120 albino individuals with oculocutaneous albinism (OCA). Refractive errors were evaluated objectively and subjectively by retinoscopy, and followed by cycloplegic refraction to reconfirm the results. Best-corrected visual acuity (BCVA) was also assessed binocularly. One hundred and twenty albino subjects were examined, ranging in age from 4 to 25 years (median 12 years), 71 (59 %) boys and 49 (41 %) girls. All exhibited horizontal pendular nystagmus. Mean visual acuity improved from 0.98 (0.33) logMAR to 0.77 (0.15) logMAR after refraction (p albinism who were hyperopic more than +1.5 D hardly improved from refraction. With the rule (WTR) astigmatism was more present (37.5 %) than against the rule (ATR) astigmatism (3.8 %). Patients with astigmatism less than 1.5 D improved in 15/32 of cases (47 %) by 2 lines or more. Patients with astigmatism equal to or more than 1.5 D in any axis improved in 26/54 of cases (48 %) by 2 lines or more. Refraction improves visual acuity of children with oculocutaneous albinism in a Sub-Saharan African population in Malawi. The mean improvement was 2 logMAR units.

  20. Phacoemulsification and intraocular lens implantation in patients with oculocutaneous albinism.

    Science.gov (United States)

    Dávila, Pedro J; Ulloa-Padilla, Jan P; Izquierdo, Natalio J

    2017-01-01

    To evaluate the benefits of phacoemulsification and intraocular lens implantation in patients with oculocutaneous albinism (OCA). The charts of 195 patients with OCA who visited a local eye clinic were reviewed. All of these patients had genetic linkage analysis to establish OCA type. Frequencies and Paired t-test analysis were determined. Of the 195 patients, nine (4.6%) underwent clear cornea phacoemulsification with intraocular lens implantation. Seven of the nine patients with OCA had the Hermansky-Pudlak (HPS) type 1; two had OCA type 1. Pre-operative BCVA of all eyes ranged from 1.0 to 2.3 logMAR with a mean of 1.42 logMAR and a standard deviation of 0.41 logMAR. Post-operative BCVA of all eyes ranged from 1.0 to 1.30 logMAR with a mean of 1.04 logMAR and a standard deviation of 0.10 logMAR. BCVA improved after phacoemulsification surgery and intraocular lens implantation (p = 0.002). Pre-operative astigmatism of all eyes ranged from +0.50 to +5.75 with a mean of +2.25 and a standard deviation of +2.40. Post-operative astigmatism of all eyes ranged from +0.50 to +2.00 with a mean of +1.23 and a standard deviation of +0.42. Astigmatism improved after phacoemulsification surgery and intraocular lens implantation (p = 0.05). Nine patients with OCA who underwent phacoemulsification and intraocular lens implant experienced improved visual acuity and reduced astigmatism post-operatively. These results suggest cataract surgery may improve vision and refractive errors, and thus quality of life, in patients with albinism.

  1. Contact lens fitting after photorefractive keratectomy.

    OpenAIRE

    Astin, C. L.; Gartry, D S; McG Steele, A. D.

    1996-01-01

    AIMS/BACKGROUND: This study evaluated contact lens fitting and the longer term response of the photorefractive keratectomy (PRK) cornea to lens wear. In PRK for myopia problems such as regression, anterior stromal haze, irregular astigmatism, halo aberration, and anisometropia have been reported. Certain patients therefore require contact lens correction to obtain best corrected visual acuity (BCVA). METHOD: From an original cohort of 80 patients, 15 were dissatisfied with their visual outcom...

  2. [Refractive surgery--possibilities to maximize postoperative visual acuity].

    Science.gov (United States)

    Tudor, Corina; Hubert, Cristina

    2006-01-01

    Laser refractive surgery has an ascendant evolution on the context of the progress in the medical field. The functional result can be negatively influenced by residual errors, irregular astigmatism or anisometropia, situations in which rigid gas permeable (RGP) contact lenses are a successful alternative in optimizing visual acuity. The paper presents the particularities and the protocol of RGP fitting, outlining the contribution of the corneal topography in the ocular pre and post-operative evaluation.

  3. Corneal Biomechanics in Ectatic Diseases: Refractive Surgery Implications

    OpenAIRE

    Ambr?sio, Jr, Renato; Correia, Fernando Faria; Lopes,Bernardo; Salom?o, Marcella Q.; Luz,Allan; Daniel G Dawson; Elsheikh, Ahmed; Vinciguerra, Riccardo; Vinciguerra, Paolo; Roberts, Cynthia J.

    2017-01-01

    Background: Ectasia development occurs due to a chronic corneal biomechanical decompensation or weakness, resulting in stromal thinning and corneal protrusion. This leads to corneal steepening, increase in astigmatism, and irregularity. In corneal refractive surgery, the detection of mild forms of ectasia pre-operatively is essential to avoid post-operative progressive ectasia, which also depends on the impact of the procedure on the cornea. Method: The advent of 3D tomography is proven as a ...

  4. The biomechanical properties of the cornea and anterior segment parameters

    OpenAIRE

    Hwang, Ho Sik; Park, Seh Kwang; Kim, Man Soo

    2013-01-01

    Background To investigate the biomechanical properties of the cornea measured with the Ocular Response Analyzer (ORA) and their association with the anterior segment parameters representing the geometric dimensions including the corneal volume and anterior chamber volume. Methods A retrospective review of 1020 patients who visited the BGN Eye Clinic was done. The mean radius of the corneal curvature, corneal astigmatism, corneal volume, anterior chamber depth, and anterior chamber volume were...

  5. [Supine cyclotorsion and asphericity].

    Science.gov (United States)

    Lehnert, R; Müller, M; Liekfeld, A

    2007-08-01

    Customised ablation to correct refractive errors is becoming more and more important today. Preoperative examinations are performed in a seated position while laser surgery is carried out in the supine position. It is well known that cyclotorsions occur but until now there have not been any investigations on possible changes in astigmatism, root mean square (RMS) and asphericity. 18 eyes of 14 individuals were measured in both the seated and the supine positions with a mobile videokeratoscope, the Keratron Scout (Optikon). A change from the seated to the supine position caused cyclotorsion in left eyes from - 9 degrees to 7 degrees (p = 0.56) and from - 8 degrees to 8 degrees (p = 0.53) in right eyes. The average amount of change of the cyclotorsion was 3.6 degrees. The overall power of astigmatism increased to 0.3 D and decreased to 0.2 D compared to astigmatism in a seated position (p = 0.06). The root mean square (RMS) of the corneal wavefront increased to 0.20 microm and decreased to 0.24 microm in comparison to the same parameter in a seated position (p = 0.36). The asphericity average changed from - 0.19 in a seated position to - 0.16 in a supine position (p = 0.04). Cyclotorsion is statistically not significant when changing from a seated to a supine position as both excyclo- and incyclotorsion occur. Since individual cyclotorsion is clinically relevant, this has been taken into account by the latest laser systems. Changes in astigmatism and statistically significant changes in asphericity may be the reason for suboptimal customised refractive surgery. It must be considered whether the preoperative measurements for laser ablation in the supine position should not also be carried out in the supine position.

  6. The refractive outcome of Toric Lentis Mplus implant in cataract surgery

    Directory of Open Access Journals (Sweden)

    Patrick J Chiam

    2016-05-01

    Full Text Available AIM: To evaluate the refractive outcome of Toric Lentis Mplus intraocular lens (IOL implant. METHODS: This is a retrospective case series. Consecutive patients with corneal astigmatism of at least 1.5 D had Toric Lentis Mplus IOL implant during cataract surgery. The exclusion criteria included irregular astigmatism on corneal topography, large scotopic pupil diameter (>6 mm, poor visual potential and significant ocular comorbidity. Postoperative manifest refraction, uncorrected distance visual acuity (UDVA, best-corrected distance visual acuity (BCVA, uncorrected intermediate visual acuity (UIVA at 3/4 m and uncorrected near visual acuity (UNVA were obtained. RESULTS: There were 70 eyes from 49 patients in this study. Patients were refracted at a median of 8.9wk (range 4.0 to 15.5 from the operation date. Sixty-five percent of eyes had 6/7.5 (0.10 logMAR or better, and 99% 6/12 (0.30 logMAR or better postoperative UDVA. Eighty-nine percent could read Jaeger (J 3 (0.28 logMAR and 95% J5 (0.37 logMAR at 40 cm. The median magnitude of astigmatism decreased from 1.91 D to 0.49 D (Wilcoxon, P<0.001 after the operation. The range of the cylindrical error was reduced from 1.5-3.95 D (keratometric preoperatively to 0.00-1.46 D (subjective refraction transposed to corneal plane postoperatively. CONCLUSION: Toric Lentis Mplus IOL has good predictability in reducing preexisting corneal astigmatism.

  7. Seven year follow-up after advanced surface ablation with excimer laser for treatment of myopia: Long-term outcomes of cooling PRK and LASEK

    DEFF Research Database (Denmark)

    Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob

    , Odense University Hospital. Inclusion criteria: Age 20-50 years at time of surgery, pre-operative CDVA ≤ 0.10 (logMAR) and no other ocular conditions than myopia with or without astigmatism of maximum 3 D. Exclusion criteria: Pregnancy and eyes having undergone re-treatment. A MEL80 flying-spot excimer......, corneal densitometry and patient satisfaction, although the long-term predictability of cPRK seemed better. Financial Disclosures: None...

  8. Suture-related complications after congenital cataract surgery: Vicryl versus Mersilene sutures.

    Science.gov (United States)

    Bar-Sela, Shai M; Spierer, Oriel; Spierer, Abraham

    2007-02-01

    To evaluate 10-0 polyester sutures (Mersilene) and 10-0 absorbable polyglactin sutures (Vicryl) for small-incision congenital cataract surgery. Goldschleger Eye Institute, Sheba Medical Center, Tel-Aviv University, Tel-Aviv, Israel. A retrospective review comprised 51 patients (70 eyes) who had small-incision congenital cataract extraction and intraocular lens implantation between 1999 and 2005. Surgery was done using Mersilene sutures or Vicryl sutures. Retinoscopy and a careful examination for suture-related complications were done 1 week after surgery and then every month for 6 months. The sutures were removed in cases of local tissue reaction but not for high postoperative astigmatism. The t test was used to evaluate postoperative astigmatism and the Fisher exact test, to evaluate the difference in the incidence of suture-related complications. The patients' age ranged from 2 months to 15 years. Ten cases (18%) of corneal vascularization occurred in the Mersilene group during the 6-month follow-up period. This necessitated suture removal, after which 1 incident of endophthalmitis occurred. In contrast, no suture-related complications were noted in the Vicryl group during that time. The difference in the incidence of complications between the 2 groups approached statistical significance (P = .07). Mean astigmatism 1 week postoperatively was 2.3 diopters (D) +/- 2.1 (SD) in the Mersilene group, which was significantly higher than in the Vicryl group (mean 1.4 +/- 1.1 D) (P = .038). However, the mean astigmatism decreased to less than 1.0 D in both groups during the 6-month follow-up period. Vicryl sutures are recommended for small-incision congenital cataract surgery.

  9. The removal of 10/0 polyester (Mersilene) sutures after small incision congenital cataract surgery.

    Science.gov (United States)

    Bar-Sela, S M; Spierer, O; Spierer, A

    2008-01-01

    To evaluate the use of 10/0 polyester (Mersilene) sutures for closure of small corneal incision after congenital cataract surgery. The authors retrospectively reviewed the medical records of 58 cases (42 patients) who underwent congenital cataract extraction and intraocular lens implantation between 1999 and 2004, using Mersilene sutures. An examination looking for suture-related complications and retinoscopy was done 1 week after surgery and then every month for 6 months. The sutures were removed in cases of local tissue reaction, but not due to high postoperative astigmatism. Paired t-test was used to compare patients' age and astigmatism level in those cases who had suture removal (Group 1) as opposed to those who did not (Group 2). In 10 cases (17%) corneal vascularization, necessitating suture removal, was found during 6-month follow-up period, without the trigger of loose suture. Patient age was 3.5+/-3.3 years and 4.4+/3.3 years in Groups 1 and 2, respectively. At 1 week postoperatively the astigmatism value was 1.7+/-1.7 diopter (D) and 2.3+/-2.2 D in Groups 1 and 2, respectively, and it reduced to 0.9+/-0.8 in both groups at 6 months postoperatively. One case of endophthalmitis was encountered 2 days after suture removal. Removal of Mersilene sutures after congenital cataract surgery is required in cases of corneal vascularization, occurring during the first months postoperatively. Owing to the risk of general anesthesia and infection, suture removal should be considered with caution in cases of postoperative astigmatism.

  10. Intrastromal corneal suture for small incision cataract surgery.

    Science.gov (United States)

    Chipont Benabent, E; Artola Roig, A; Martínez Toldos, J J

    1996-01-01

    Proper wound closure is important in preventing postoperative endophthalmitis. We developed an intrastromal corneal suture technique that uses some principles of the running, locked, intradermal suture for light-tension skin wounds. It achieves close approximation of the wound edges, reduces postoperative wound care and the risk of wound infection in clean surgical wounds, and obviates suture removal. It may also help prevent endophthalmitis and early against-the-rule astigmatism without the complications associated with external suture exposure.

  11. Controlled reshaping of the front surface of the cornea through its full-area ablation outside of the optical zone with a Gaussian ArF excimer laser beam

    Science.gov (United States)

    Semchishen, A. V.; Semchishen, V. A.

    2014-01-01

    We studied in vitro the response of the topography of the cornea to its full-area laser ablation (the laser beam spot diameter is commensurable with the size of the interface) outside of the central zone with an excimer laser having a Gaussian fluence distribution across the beam. Subject to investigation were the topographically controlled surface changes of the anterior cornea in 60 porcine eyes with a 5 ± 1.25-diopter artificially induced astigmatism, the changes being caused by laser ablation of the stromal collagen in two 3.5-mm-dia. circular areas along the weaker astigmatism axis. Experimental relationships are presented between the actual astigmatism correction and the expected correction for the intact optical zones 1, 2, 3, and 4 mm in diameter. The data for each zone were approximated by the least-squares method with the function d = a + bx. The coefficient b is given with the root-mean-square error. The statistical processing of the data yielded the following results: d = (0.14 ± 0.037)x for the 1-mm-dia. optical zone, (1.10 ± 0.036)x for the 2-mm-dia. optical zone, (1.04 ± 0.020)x for the 3-mm-dia. optical zone, and (0.55 ± 0.04)x for the 4-mm-dia. optical zone. Full astigmatism correction was achieved with ablation effected outside of the 3-mm-dia. optical zone. The surface changes of the cornea are shown to be due not only to the removal of the corneal tissue, but also to the biomechanical topographic response of the cornea to its strain caused by the formation of a dense pseudomembrane in the ablation area.

  12. Systematic review comparing penetrating keratoplasty and deep anterior lamellar keratoplasty for management of keratoconus.

    Science.gov (United States)

    Henein, Christin; Nanavaty, Mayank A

    2017-02-01

    Perception of reduced incidence of graft rejection after deep anterior lamellar keratoplasty (DALK) has attracted many surgeons towards this technique in keratoconus. This review aims to compare the visual, refractive and graft outcomes after penetrating keratoplasty (PK) and DALK for keratoconus. Electronic searches of PubMed, MEDLINE, EMBASE, Latin American and Caribbean Health Sciences Literature database (LILACS), metaRegister of Controlled Trials (mRCT), ClinicalTrial.gov and the WHO International Clinical Trials Registry Platform (ICTRP) were performed. We included randomized control trials (RCTs) and comparative studies to assess primary and secondary outcomes after PK and DALK in eyes with keratoconus. Primary outcome was best-corrected visual acuity (BCVA) LogMAR at ≥6 months. Secondary outcomes included number of patients with BCVA≥0 LogMAR, uncorrected visual acuity (UCVA) LogMAR, spherical equivalent (SE), refractive and keratometric astigmatism, endothelial cell density (ECD) cell/mm2, graft rejection and graft survival. Eighteen studies (including 2 RCTs) compared DALK (965 eyes) and PK (2402 eyes) for keratoconus. There was strong evidence through RCTs suggesting better LogMAR BCVA at ≥6 months and better LogMAR UCVA with PK; reduced refractive astigmatism and rejection with DALK and no difference in SE and keratometric astigmatism. Moreover, there was weak evidence to suggest better BCVA≥0 LogMAR after PK and no difference in ECD between the two techniques. Despite the popularity of DALK amongst corneal surgeons for keratoconus, there is a paucity of high quality RCTs. The existing limited evidence confirms reduced rejection and refractive astigmatism with DALK but better visual outcomes with PK. Internationally agreed data sets and follow-up protocol are warranted. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  13. Compact adaptive optic-optical coherence tomography system

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, Scot S [Livermore, CA; Chen, Diana C [Fremont, CA; Jones, Steven M [Danville, CA; McNary, Sean M [Stockton, CA

    2011-05-17

    Badal Optometer and rotating cylinders are inserted in the AO-OCT to correct large spectacle aberrations such as myopia, hyperopic and astigmatism for ease of clinical use and reduction. Spherical mirrors in the sets of the telescope are rotated orthogonally to reduce aberrations and beam displacement caused by the scanners. This produces greatly reduced AO registration errors and improved AO performance to enable high order aberration correction in a patient eyes.

  14. Visual outcomes after implantation of a novel refractive toric multifocal intraocular lens

    Directory of Open Access Journals (Sweden)

    Talita Shimoda

    2014-04-01

    Full Text Available Purpose: To assess the postoperative outcomes of a novel toric multifocal in traocular lens (IOL in patients with cataract and corneal astigmatism. Methods: This prospective nonrandomized study included patients with cataract, corneal astigmatism, and a motivation for spectacle independence. In all patients, a Rayner M-flex® T toric IOL was implanted in the capsular bag. Three months after surgery, the distance, intermediate, and near visual acuities; spherical equivalent; residual refractive astigmatism; defocus curve; and contrast sensitivity were evaluated. A patient satisfaction and visual phenomena questionnaire was administered to all patients. Results: Thirty-four eyes of 18 patients were included in this study. Three months after surgery, the mean corrected distance visual acuity (logMAR was 0.00 ± 0.08 at 6 m, 0.20 ± 0.09 at 70 cm, and 0.08 ± 0.11 at 40 cm. Uncorrected distance vision acuity was 20/40 or better in 100% eyes. The preoperative mean refractive cylinder (RC was -2.19 (SD: ± 0.53. After a 3-month follow-up, the average RC was -0.44 D (SD: ± 0.27; p<0.001. Contrast sensitivity levels were high. At the last follow-up, 87.5% patients were spectacle-independent for near, intermediate, and distance vision, and approximately 44% patients reported halos and glare. Conclusion: Toric multifocal IOL implantation in patients with cataract and corneal astigmatism using the Rayner M-flex® T toric IOL was a simple, safe, and accurate option. This technology provides surgeons with a feasible option for meeting patient expectations of an enhanced lifestyle resulting from decreased spectacle dependence.

  15. Compact adaptive optic-optical coherence tomography system

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, Scot S [Livermore, CA; Chen, Diana C [Fremont, CA; Jones, Steven M [Danville, CA; McNary, Sean M [Stockton, CA

    2012-02-28

    Badal Optometer and rotating cylinders are inserted in the AO-OCT to correct large spectacle aberrations such as myopia, hyperopic and astigmatism for ease of clinical use and reduction. Spherical mirrors in the sets of the telescope are rotated orthogonally to reduce aberrations and beam displacement caused by the scanners. This produces greatly reduced AO registration errors and improved AO performance to enable high order aberration correction in a patient eyes.

  16. Spectacle lenses designed for the modified Listing eye rotation

    Science.gov (United States)

    Stephenson, Philip C. L.

    2004-02-01

    Knowledge of the way the eye rotates when changing gaze direction is important for the lens design process. Listing's law of eye rotation conveniently describes that rotation for distant vision. Here, a recently discovered departure from Listing's law in near vision is examined. Although lens designs that accommodate the modified rotations can be produced, as demonstrated here, the benefits to the wearer are unlikely to be perceptible except perhaps in cases of highly astigmatic vision.

  17. Windshield optics.

    Science.gov (United States)

    Irland, M J

    1969-09-01

    Windshield design involves compromises among mechanical, aerodynamic, aesthetic, thermal, and safety requirements, yet the windshield must be considered as an optical element. Four types of optical errors to be controlled by proper design are discussed, viz., astigmatism, binocular differential deviation of the line of sight, relative angular acceleration of image elements, and ghost images. Empirical limiting values for the last three and procedures for their control are given.

  18. Relationships between keratometry and collagen fibrillar structure of cornea by circular polarization biomicroscopy.

    Science.gov (United States)

    Hwang, Hosik; Kim, Eun Chul; Kim, Man Soo

    2011-04-01

    To evaluate the relationships between keratometry and collagen fibrillar structure of cornea by circular polarization biomicroscopy. Thirty-four subjects (63 eyes) were included in this study. Intraocular pressure (IOP) was measured, and keratometry was done with an automated keratometer. When the corneal astigmatism was larger than 0.75 diopter, corneal topography was done. After pupil dilation, the examiner placed a circular polarizing filter in front of the subject's eye. The images were captured by a camera connected to the slit lamp. Interfocal distance and angle were measured with ImageJ. The correlations between corneal astigmatism and interfocal distance-angle were examined by double angle vector diagram. Scalar analyses were done for the correlations between subject age and interfocal distance, between IOP and interfocal distance, and between mean cornea power and interfocal distance. The mean age of the 34 subjects was 59 ± 16 years. Mean interfocal distances and angles determined by double angle vector diagram were 4.67 mm and -20.5 degrees in the right eye and 3.73 mm and +24.2 degrees in the left eye. The correlation between age and interfocal distance and between IOP and interfocal distance were statistically insignificant (P = 0.913 and 0.361, respectively). The interfocal distance and angle showed no statistically significant correlation with corneal astigmatism by vector analysis (P = 0.221 and 0.850, respectively). The fibrillar structure pattern in circular polarizing biomicroscopy showed no statistically significant relationship with the bow tie pattern in corneal topography (P = 0.762). However, analysis of the correlation between mean corneal power and interfocal distance showed a statistically significant, but weak positive correlation (r = 0.326, P = 0.019). Interfocal distance determined through circular polarizing biomicroscopy showed a positive correlation with mean corneal power. But age, IOP, and corneal astigmatism did not show a

  19. Fourier analysis algorithm for the posterior corneal keratometric data: clinical usefulness in keratoconus.

    Science.gov (United States)

    Sideroudi, Haris; Labiris, Georgios; Georgantzoglou, Kimon; Ntonti, Panagiota; Siganos, Charalambos; Kozobolis, Vassilios

    2017-07-01

    To develop an algorithm for the Fourier analysis of posterior corneal videokeratographic data and to evaluate the derived parameters in the diagnosis of Subclinical Keratoconus (SKC) and Keratoconus (KC). This was a cross-sectional, observational study that took place in the Eye Institute of Thrace, Democritus University, Greece. Eighty eyes formed the KC group, 55 eyes formed the SKC group while 50 normal eyes populated the control group. A self-developed algorithm in visual basic for Microsoft Excel performed a Fourier series harmonic analysis for the posterior corneal sagittal curvature data. The algorithm decomposed the obtained curvatures into a spherical component, regular astigmatism, asymmetry and higher order irregularities for averaged central 4 mm and for each individual ring separately (1, 2, 3 and 4 mm). The obtained values were evaluated for their diagnostic capacity using receiver operating curves (ROC). Logistic regression was attempted for the identification of a combined diagnostic model. Significant differences were detected in regular astigmatism, asymmetry and higher order irregularities among groups. For the SKC group, the parameters with high diagnostic ability (AUC > 90%) were the higher order irregularities, the asymmetry and the regular astigmatism, mainly in the corneal periphery. Higher predictive accuracy was identified using diagnostic models that combined the asymmetry, regular astigmatism and higher order irregularities in averaged 3and 4 mm area (AUC: 98.4%, Sensitivity: 91.7% and Specificity:100%). Fourier decomposition of posterior Keratometric data provides parameters with high accuracy in differentiating SKC from normal corneas and should be included in the prompt diagnosis of KC. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.

  20. Analysis of photoastigmatic keratectomy with the cross-cylinder ablation

    Directory of Open Access Journals (Sweden)

    Nicola Rosa

    2012-01-01

    Full Text Available Aim: The aim was to evaluate the safety and efficacy of the "cross-cylinder" technique in the correction of astigmatism. Setting and Design: A prospective interventional study from a university eye department was conducted. Material and Methods: The photoastigmatic refractive keratectomy (PARK using the "cross-cylinder" technique was performed in 102 eyes of 84 patients with at least 0.75 D of astigmatism. The study population was divided into two groups: in the first group the preoperative astigmatic power ranged from −0.75 D to −3.00 D (group 1, in the second group it ranged from −3.25 D to −6.00 D (group 2. Group 1 included 82 eyes of 67 patients (29 males and 38 females with a mean cylinder power of −1.90 ± 0.63 D, group 2 included 20 eyes of 17 patients (13 males and 4 females with a mean cylinder power of -4.28 ± 0.76 D. All eyes were targeted for emmetropia. The results were evaluated using Calossi′s vector analysis method. Six-month postoperative outcomes are presented. Results: Six months after PARK the mean sphere for the entire cohort was +0.28 ± 0.75 D (range +2.5 to −2 D, the mean cylindrical power was +0.33 ± 0.51 D (range +2.5 to −1.25 D and the mean spherical equivalent refraction was +0.73 ± 0.81 D (range +1.75 to −2 D. Conclusions: The cross-cylinder technique may be safely used with predictable results for the correction of astigmatism.

  1. Big-bubble deep anterior lamellar keratoplasty assisted by femtosecond laser in children.

    Science.gov (United States)

    Buzzonetti, Luca; Petrocelli, Gianni; Valente, Paola

    2012-09-01

    To report the early results of big-bubble deep anterior lamellar keratoplasty assisted by femtosecond laser in children. Five eyes of 5 pediatric patients were enrolled in the study; 3 had keratoconus and 2 corneal opacities. An IntraLase 60 KHz femtosecond laser (Abbott Medical Optics, Inc) was used to create mushroom incisions on both donor and recipient corneas. All patients were evaluated for best-corrected visual acuity, spherical equivalent, refractive astigmatism, keratometric astigmatism, mean K value, and corneal thinnest point. The big bubble was always achieved, and all eyes were treated successfully without intraoperative complications. The follow-up was of 10 months. At 10 months (at least 3 months after complete suture removal), the mean postoperative best-corrected visual acuity was 20/30 (range, 20/25 to 20/30), mean spherical equivalent was -1.8 ± 1.2 diopters (D) (range, -0.25 to 1.25 D), mean refractive astigmatism was 1.8 ± 1.4 D (range, 0 to 4.0 D), mean keratometric astigmatism was 5.1 ± 2.1 D (range, 3.5 to 8.59 D), mean K value was 46.2 ± 0.8D, and mean corneal thinnest point was 581 ± 46 μm (range, 511-638 μm). Our early findings suggest that the big-bubble technique in deep anterior lamellar keratoplasty assisted by femtosecond laser is safe and effective also in pediatric patients in the attempt to decrease the rejection percentage, improve the refractive outcome, and then provide an antiamblyopic effect.

  2. Management of visual disturbances in albinism: a case report

    OpenAIRE

    Omar Rokiah; Idris Siti; Meng Chung; Knight Victor

    2012-01-01

    Abstract Introduction A number of vision defects have been reported in association with albinism, such as photophobia, nystagmus and astigmatism. In many cases only prescription sunglasses are prescribed. In this report, the effectiveness of low-vision rehabilitation in albinism, which included prescription of multiple visual aids, is discussed. Case presentation We present the case of a 21-year-old Asian woman with albinism and associated vision defects. Her problems were blurring of distant...

  3. Exploded representation of a refracting surface

    Directory of Open Access Journals (Sweden)

    W.H. Heath

    2005-01-01

    Full Text Available The concept of the exploded refracting sur-face is useful in the optics of contact lenses and vision underwater. The purpose of this paper is to show how to represent a refracting surface as an exploded pair of surfaces separated by a gap of zero width.  The analysis is in terms of linear optics and allows for astigmatic and non-coaxial cases.

  4. Effects of rigid contact lenses on optical coherence tomographic parameters in eyes with keratoconus.

    Science.gov (United States)

    Uzunel, Umut Duygu; Kusbeci, Tuncay; Yuce, Berna; Yüksel, Bora

    2015-07-01

    The aim was to evaluate the effect of irregular astigmatism on the retinal nerve fibre layer (RNFL), macular thickness and ganglion cell analysis obtained by spectral domain optical coherence tomography (OCT) in eyes with keratoconus. Fifty-two eyes of 31 patients (20 females) with keratoconus that required correction of irregular astigmatism with rigid gas-permeable (RGP) contact lenses were included to this study. The average, superior, nasal, inferior, temporal and 12 clock hour sector's RNFL, ganglion cell and macular thickness analyses before and 30 minutes after RGP contact lens (Rose K2 -Menicon Z material, David Thomas Contact Lenses Ltd, Northampton, United Kingdom) wear were performed to all patients with Cirrus HD spectral domain optical coherence tomography. The average thickness of the retinal nerve fibre layer, the thickness at the nasal quadrants and 1-2-3-4 o'clock hour sectors and mean signal strength were increased significantly by RGP contact lens wearing independent of the stage of keratoconus. Central sub-field thickness increased after correction with RGP contact lens (p = 0.037). After wearing RGP contact lenses, changes on ganglion cell analysis were not significant (all p values ≥ 0.111). OCT is a widely used device for retinal nerve fibre layer and macular thickness evaluation in patients with glaucoma and macular diseases. The study demonstrates that OCT parameters such as retinal nerve fibre layer, central sub-field thickness and mean signal strength are affected by irregular astigmatism. Correction of irregular astigmatism with RGP contact lenses should be recommended before analysing keratoconic eyes to obtain optimum results on OCT measurements. © 2015 The Authors. Clinical and Experimental Optometry © 2015 Optometry Australia.

  5. Variation of contrast sensitivity after femtosecond laser in situ keratomileusis in changes environments

    Directory of Open Access Journals (Sweden)

    Jing Zhou

    2015-01-01

    Full Text Available AIM: To evaluate the difference of contrast sensitivity(CSin photopic and scotopic environments in eyes with myopia and myopic astigmatism operated with femtosecond laser in situ keratomileusis(femto-LASIKand laser in situ keratomileusis(LASIK.METHODS: In a prospective study 160 myopia and myopic astigmatism patients' eyes were involved, which accepted femto-LASIK or LASIK in our hospital from January 2010 to February 2012. The myopia degree was -1.50~-10.00D, the astigmatism degree ≤-6.0D. Eighty eyes were treated with femto-LASIK in group A, and 80 eyes were treated with LASIK in group B, All patients in the treatment group completed the final 6mo of follow-up. The uncorrected visual acuity(UCVAand the best spectacle-corrected visual acuity(BSCVA, objective and manifest refractions, results of slit-lamp examination, the side effects, intraocular pressure, corneal topography, CS in photopic and scotopic environments were noted.RESULTS: All of operations on 160 cases were successful without severe complication after 6 mo follow-up. CS of femto-LASIK group(group Aat each spatial frequency environment were higher than that of LASIK group(group B. In group A, after 1mo the photopic CS, after 3mo of scotopic CS recovered to the preoperative level, 6mo after surgery improved than before the operation. In group B, after 3mo photopic CS to the preoperative level, scotopic CS at 6mo after operation was still not recovered to the preoperative level.CONCLUSION:Femto-LASIK for correction of myopia and myopic astigmatism, in improving the postoperative contrast sensitivity under shade environment has more advantages than LASIK.

  6. Endothelial lamellar keratoplasty using an artificial anterior chamber and a microkeratome.

    Science.gov (United States)

    Behrens, Ashley; Ellis, Kenneth; Li, Li; Sweet, Paula M; Chuck, Roy S

    2003-04-01

    To compare postoperative astigmatic change and graft stability using 2 different donor button diameters in endothelial lamellar keratoplasty to treat corneal endothelial failure. A 200- micro m-thick corneal flap keratectomy was performed in human donor corneoscleral rims (n = 20; 10 donors and 10 recipients) using an artificial anterior chamber and a manual microkeratome (ALTK System; Moria USA, Doylestown, Pa). After flap reflection, stromal bed trephination was performed to obtain a disc consisting of posterior stroma, Descemet membrane, and endothelium. Host beds of 7.0 mm and 7.25-mm (n = 5) or 7.50-mm (n = 5) donor buttons were obtained using a freehand trephine. The graft was secured with 8 interrupted sutures (10-0 nylon) in the stromal bed. The flap was sutured with 3 interrupted sutures. Transplanted corneas were submitted to increasing intrachamber pressures to detect graft stability, and preoperative and postoperative videokeratographic data were recorded to assess astigmatic change. The mean (SD) postoperative astigmatic change was 1.14 (3.17) diopters (D) in the 7.25-mm donor button group and 2.27 (1.77) D in the 7.50-mm donor button group (P =.69). Mean (SD) resisted pressures of 75.4 (44.81) mm Hg and 100.4 (46.86) mm Hg were observed in the 7.25-mm and 7.50-mm groups, respectively (P =.54). Both donor button sizes exhibited similar graft stability and astigmatic postoperative change in this experimental model. As endothelial lamellar keratoplasty becomes further developed as a clinical alternative to penetrating keratoplasty, this laboratory model system should be useful in evaluating different mechanical factors that contribute to graft success.

  7. Impact of corneal aberrations on through-focus image quality of presbyopia-correcting intraocular lenses using an adaptive optics bench system.

    Science.gov (United States)

    Zheleznyak, Len; Kim, Myoung Joon; MacRae, Scott; Yoon, Geunyoung

    2012-10-01

    To measure the impact of corneal aberrations on the through-focus image quality of presbyopia-correcting intraocular lenses (IOLs) using an adaptive optics IOL metrology system. Flaum Eye Institute, University of Rochester, Rochester, New York, USA. Experimental study. An adaptive optics IOL metrology system comprising a model eye, wavefront sensor, deformable mirror, and an image-capturing device acquired through-focus images of a letter chart with 3.0 mm and 5.0 mm pupil diameters. The system was used to induce corneal astigmatism and higher-order aberrations (HOAs) in previously measured pseudophakic presbyopic eyes. A single-optic accommodating IOL (Crystalens HD (HD500), an apodized (Restor +3.0 diopter [D] SN6AD1) and full-aperture (Tecnis ZM900) diffractive multifocal IOL, and a monofocal IOL (Acrysof SN60AT) were evaluated. Image quality was quantified using the correlation-coefficient image-quality metric. The single-optic accommodating IOL and monofocal IOL performed similarly; however, with a 3.0 mm pupil, the former had better intermediate (1.50 D) image quality. The multifocal IOLs had bimodal through-focus image quality trends. Corneal astigmatism reduced through-focus image quality and depth of focus with all IOLs; however, the multifocal IOLs had the most severe decline in depth of focus. Ocular spherical aberration had the strongest impact on image quality when typical pseudophakic corneal HOAs were present. The uncorrected corneal astigmatism and HOAs in pseudophakic eyes significantly affected through-focus performance of presbyopia-correcting IOLs. Although multifocal IOLs significantly increased depth of focus, this benefit diminished when more than 0.75 D astigmatism remained uncorrected. Residual ocular spherical aberration had a significant effect on image quality in the presence of other corneal HOAs. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  8. Customized photorefractive keratectomy to correct high ametropia after penetrating keratoplasty: A pilot study.

    Science.gov (United States)

    De Rosa, Giuseppe; Boccia, Rosa; Santamaria, Carmine; Fabbozzi, Lorenzo; De Rosa, Luigi; Lanza, Michele

    2015-01-01

    To evaluate preliminarily the safety and efficacy of customized photorefractive keratectomy (PRK) to correct ametropia and irregular astigmatism after penetrating keratoplasty (PK). This pilot study included five eyes of five patients with a mean spherical equivalent of -5.1±1.46D (range from -2.75 to -6.50D). In all cases, ametropia and irregular astigmatism was corrected with topography-guided customized PRK. Ocular examinations with topographic analysis were performed preoperatively as well as at 1, 3 and 6 months after surgery. All eyes gained postoperatively at least three Snellen lines of uncorrected visual acuity. Mean refractive spherical equivalent was 0.62±0.63D (range from -0.25 to -1.75D) at 6 months postoperatively. Our pilot study suggests that customized PRK can be a safe and effective method for treating ametropia and irregular astigmatisms after PK. Future studies with larger samples and longer follow-ups should be performed to confirm these results. Copyright © 2013 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  9. Application of manual small incision cataract surgery in age-related cataract

    Directory of Open Access Journals (Sweden)

    Bi-Hua Xie

    2015-08-01

    Full Text Available AIM: To research the practicability of manual small incision cataract surgery(MSICS.METHODS: Three hundred and six eyes age-related cataract were taken MSICS and 306 eyes received phacoemulsification(Phaco group. Visual acuity, the refractive and the loss ratio of cornea endothelia cells were observed and compared after surgery. RESULTS: Uncorrected visual acuity of 33 eyes(10.78%and 76 eyes(24.84%was >1.0 in 7d and 3mo after MSICS. The loss ratio of cornea endothelia cells was 8.7%, The recursive of corneal astigmatism was on average 0.75D compared with preoperation. Uncorrected visual acuity of 63 eyes(20.59%and 92 eyes(30.07%was >1.0 in 7d and 3mo after phacoemulsification. The loss ratio of cornea endothelia cells was 21.67%. The average corneal astigmatism was -0.5DC and -0.45DC in MSICS group and Phaco group respectively, but 3mo after surgery, there was no significant difference on corneal astigmatism between the two groups(P>0.05.CONCLUSION: Due to the use of Phaco machine, the cost is higher in Phaco group, and the Phaco mechanical stimulation, injury, ultrasonic energy and perfusion solutions have effects on corneal endothelium, visual acuity recovery at early postoperative is slow. However, MSICS dose not use Phaco machine, works by hands, the cost is lower, and visual acuity recovery at early postoperative is faster.

  10. Application of the holmium:YAG laser for refractive surgery III

    Science.gov (United States)

    Thompson, Vance M.; Seiler, Theo; Sacharoff, Alex C.; Durrie, Daniel S.; Aran, Alberto J.; Barnet, Ronald W.; Dulaney, David D.; Hurt, Art C., III; Mann, P. M.; Sawelson, Harold; Yanoff, Myron; Muller, David F.

    1994-06-01

    We update the continued progress of laser thermokeratoplasty (LTK) clinical trials being conducted in the U.S. for the treatment of hyperopia and hyperopic astigmatism. Data from the Phase II hyperopia investigations on 25 patients and from Phase I astigmatism trials on 30 patients is reviewed. From the hyperopia Phase IIa study, the near uncorrected visual acuity of 13 patients for whom complete follow-up results are available at 1 year shows that all 13 patients gained 2 or more lines of visual acuity (Ave. gain 3.5 lines), which indicates a significant improvement in near vision. A survey given to these hyperopia patients finds 8% could read without glasses preoperatively versus 58.3% at 1 year post-operatively. The preoperative uncorrected visual acuity of those patients treated for astigmatism in the Phase I trial showed 2 out of 30 patients or 6.7% seeing better than 20/40 versus 10 out of 27 patients or 37% at one year post-op. The one year data in both studies indicates that after an initial period of partial regression of effect, the residual correction remains relatively stable between 6 months and 1 year. Continued follow-up will be carried out to see if the corrections remain stable beyond 1 year.

  11. Anisometropia is independently associated with both spherical and cylindrical ametropia.

    Science.gov (United States)

    Qin, Xue-Jiao; Margrain, Tom H; To, Chi Ho; Bromham, Nathan; Guggenheim, Jeremy A

    2005-11-01

    To explore the associations between anisometropia and spherical ametropia, astigmatism, age, and sex. Associations between the prevalence and magnitude of anisometropia with age, sex, spherical power, and cylindrical power, were assessed in a group of 90,884 subjects attending optometry practices in the United Kingdom. Logistic regression models were used to assess the independent contribution of each explanatory variable. Logistic regression analyses that included all subjects or just those aged 20 to 40 years showed that spherical ametropia and astigmatism were independently associated with anisometropia (myopes, P Anisometropia was relatively stable between the ages of 20 and 40 years, but then became more common with age, in myopes from the age of 40 years onward (P anisometropia to a clinically significant extent. This is the first study to show an independent association between anisometropia and both spherical ametropia and astigmatism. The results also suggest that the previously noted increased prevalence of anisometropia with age occurs later in hyperopes than in myopes, once other covariates have been controlled for. However, it could not be ruled out that this latter effect was due to clinical selection bias in our sample. The findings suggest that research projects involving the recruitment of highly ametropic subjects, such as those investigating the genetics of refractive error, may benefit by avoiding the use of stringent inclusion criteria for anisometropia, because otherwise a large proportion of the relevant population will be excluded.

  12. Geometric explanation of conic-section interference fringes in a Michelson interferometer

    Science.gov (United States)

    Fang, Guangyu; Huang, Li; Xin, Li; Zhao, Haifa; Huo, Lei; Wu, Lili

    2013-09-01

    A simple geometric method based on wave-front analysis is developed to provide a concise explanation for the various interference fringes in a Michelson interferometer without the compensator plate. In view of the fact that a homocentric pencil of rays from a point light source becomes astigmatic as it passes obliquely through a glass plate, the wave-front deviation from a spherical one is obtained by calculating the astigmatic focal distance of the central ray. If the compensator plate is removed, the two central rays along the interfering paths have different astigmatic focal distances (AFDs), therefore, the optical path length difference can never be compensated with the movement of the reflected mirrors. The wave-front difference or the optical path difference is determined to the accuracy of second order by comparing the two pairs of principal curvature radii, and the trivial point-by-point calculation of the optical path length difference (OPD) is avoided. Numerical results support the theoretical analysis with great accuracy.

  13. Aberration measurement in HRTEM: Implementation and diagnostic use of numerical procedures for the highly precise recognition of diffractogram patterns

    Energy Technology Data Exchange (ETDEWEB)

    Barthel, J. [Institute of Solid State Research and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany); Thust, A., E-mail: a.thust@fz-juelich.de [Institute of Solid State Research and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany)

    2010-12-15

    The precise characterisation of the instrumental imaging properties in the form of aberration parameters constitutes an almost universal necessity in quantitative HRTEM, and is underlying most hardware and software techniques established in this field. We focus in this paper on the numerical analysis of individual diffractograms as a first preparatory step for further publications on HRTEM aberration measurement. The extraction of the defocus and the 2-fold astigmatism from a diffractogram is a classical pattern recognition problem, which we believe to have solved in a near-optimum way concerning precision, speed, and robustness. The newly gained measurement precision allows us to resolve fluctuations of the defocus and the 2-fold astigmatism and to assess thereby the optical stability of electron microscopes. Quantitative stability criteria are elaborated, which may serve as helpful guidelines for daily work as well as for microscope acceptance tests. -- Research Highlights: {yields} Algorithms for the highly precise diffractogram analysis in HRTEM are introduced. {yields} AMADEUS procedure measures defocus and astigmatism with a few Angstrom precision. {yields} Aberration measurement meets the precision requirements of 0.5 A microscopy. {yields} Quantitative criteria for the optical stability of HRTEMs are introduced.

  14. REPRINT OF: Aberration measurement in HRTEM: Implementation and diagnostic use of numerical procedures for the highly precise recognition of diffractogram patterns

    Energy Technology Data Exchange (ETDEWEB)

    Barthel, J. [Institute of Solid State Research and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany); Thust, A., E-mail: a.thust@fz-juelich.de [Institute of Solid State Research and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany)

    2011-06-15

    The precise characterisation of the instrumental imaging properties in the form of aberration parameters constitutes an almost universal necessity in quantitative HRTEM, and is underlying most hardware and software techniques established in this field. We focus in this paper on the numerical analysis of individual diffractograms as a first preparatory step for further publications on HRTEM aberration measurement. The extraction of the defocus and the 2-fold astigmatism from a diffractogram is a classical pattern recognition problem, which we believe to have solved in a near-optimum way concerning precision, speed, and robustness. The newly gained measurement precision allows us to resolve fluctuations of the defocus and the 2-fold astigmatism and to assess thereby the optical stability of electron microscopes. Quantitative stability criteria are elaborated, which may serve as helpful guidelines for daily work as well as for microscope acceptance tests. -- Research Highlights: {yields} Algorithms for the highly precise diffractogram analysis in HRTEM are introduced. {yields} AMADEUS procedure measures defocus and astigmatism with a few Angstrom precision. {yields} Aberration measurement meets the precision requirements of 0.5 A microscopy. {yields} Quantitative criteria for the optical stability of HRTEMs are introduced.

  15. What are the effects of metopic synostosis on visual function?

    Science.gov (United States)

    Macintosh, Claire; Wells, Rachel; Johnson, David; Wall, Steve

    2011-07-01

    Metopic synostosis is a premature fusion of the metopic cranial suture. Small case studies into the effects on vision have suggested that there is a raised incidence of astigmatic refractive error with increased risk of failure to develop normal vision if reconstructive surgery is delayed beyond 7 months of age. The aim of this study was to look at a much larger group of patients to give more statistical significance on the incidence of significant refractive error and strabismus in cases of metopic synostosis and compare this with that known for the general population of children at a similar age. A secondary objective was to look at the age at surgery and the visual outcome. A retrospective analysis of case notes was carried out for 64 children with a confirmed diagnosis of metopic synostosis attending the Oxford Craniofacial Unit. Twenty children (31%) were found to have a visual problem, with 18 needing glasses to correct a refractive error and 10 having strabismus. The nature of refractive error was generally hypermetropia, in some cases combined with low astigmatism (1.5 diopters [D] or less). Only 1 child was recorded as having more than 1.5 D of astigmatism. The age at surgery did not seem to influence visual outcome. The incidence of significant refractive error requiring correction and strabismus across the metopic group (31%) was higher than that found in the general population of children at a similar age (5%-11%). This reinforces the importance of orthoptic/ophthalmic surveillance in metopic synostosis.

  16. Refractive errors in Cameroonians diagnosed with complete oculocutaneous albinism

    Directory of Open Access Journals (Sweden)

    Eballé AO

    2013-07-01

    Full Text Available André Omgbwa Eballé1,3, Côme Ebana Mvogo2, Christelle Noche4, Marie Evodie Akono Zoua2, Andin Viola Dohvoma21Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon, 2Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon; 3Yaoundé Gynaeco-obstetric and Paediatric Hospital. Yaoundé, Cameroon; 4Faculty of Medicine, Université des Montagnes. Bangangté, CameroonBackground: Albinism causes significant eye morbidity and amblyopia in children. The aim of this study was to determine the refractive state in patients with complete oculocutaneous albinism who were treated at the Gynaeco-Obstetric and Paediatric Hospital, Yaoundé, Cameroon and evaluate its effect on vision.Methods: We carried out this retrospective study at the ophthalmology unit of our hospital. All oculocutaneous albino patients who were treated between March 1, 2003 and December 31, 2011 were included.Results: Thirty-five patients (70 eyes diagnosed with complete oculocutaneous albinism were enrolled. Myopic astigmatism was the most common refractive error (40%. Compared with myopic patients, those with myopic astigmatism and hypermetropic astigmatism were four and ten times less likely, respectively, to demonstrate significant improvement in distance visual acuity following optical correction.Conclusion: Managing refractive errors is an important way to reduce eye morbidity-associated low vision in oculocutaneous albino patients.Keywords: albinism, visual acuity, refraction, Cameroon

  17. Contact lens fitting post-laser-in situ keratomileusis (LASIK).

    Science.gov (United States)

    Steele, Chris; Davidson, John

    2007-05-01

    Despite recent advances in refractive surgical procedures a small proportion of patients still achieve sub-optimal results for a variety of reasons. In such cases, contact lenses may provide the only option for visual rehabilitation and restoration of binocular vision post-refractive surgery. The indications for contact lenses post-LASIK may be one, or a combination of the following: *Initial bandage lens for corneal protection. *Residual ametropia--over and under correction. *Irregular astigmatism. * Anisometropia. * Decentred ablation zones. In low powered corrections conventional soft lenses can be fitted in the normal way, giving good levels of acuity. Where there is astigmatism (>0.75 DC) then toric soft contact lenses may appropriate. Rigid lenses may prove to be the only viable option in a number of cases where visual correction is required post-refractive surgery, or in the presence of high levels of astigmatism. Fitting can be more complex however, since a conventional rigid lens cannot follow the shape of both the flattened central cornea and the relatively steeper periphery in higher corrections, as the amount of laser ablation increases. Reverse geometry lenses are indicated where there is a significant difference between the flat central ablated zone and the relatively steeper peripheral cornea. On rare occasions scleral lenses may also be indicated.

  18. Fitting contact lenses for visual rehabilitation after penetrating keratoplasty.

    Science.gov (United States)

    Wietharn, Bruce E; Driebe, William T

    2004-01-01

    To determine the optical indications for contact lens wear after corneal transplantation. The type of lenses used, fitting philosophy, visual outcomes, and complications were examined. A 4-year retrospective chart review was performed and identified 35 eyes in 30 patients wearing