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Sample records for corneal collagen cross

  1. Progress of research on corneal collagen cross-linking for corneal melting

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    Ke-Ren Xiao

    2016-06-01

    Full Text Available Corneal collagen cross-linking(CXLcould increase the mechanical strength, biological stability and halt ectasia progression due to covalent bond formed by photochemical reaction between ultraviolet-A and emulsion of riboflavin between collagen fibers in corneal stroma. Corneal melting is an autoimmune related noninfectious corneal ulcer. The mechanism of corneal melting, major treatment, the basic fundamental of ultraviolet-A riboflavin induced CXL and the clinical researches status and experiment in CXL were summarized in the study.

  2. Recent advances in corneal collagen cross-linking

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    Gitansha Shreyas Sachdev

    2017-01-01

    Full Text Available Corneal collagen cross-linking has become the preferred modality of treatment for corneal ectasia since its inception in late 1990s. Numerous studies have demonstrated the safety and efficacy of the conventional protocol. Our understanding of the cross-linking process is ever evolving, with its wide implications in the form of accelerated and pulsed protocols. Newer advancements in technology include various riboflavin formulations and the ability to deliver higher fluence protocols with customised irradiation patterns. A greater degree of customisation is likely the path forward, which will aim at achieving refractive improvements along with disease stability. The use of cross-linking for myopic correction is another avenue under exploration. Combination of half fluence cross-linking with refractive correction for high errors to prevent post LASIK regression is gaining interest. This review aims to highlight the various advancements in the cross-linking technology and its clinical applications.

  3. Induction of corneal collagen cross-linking in experimental corneal alkali burns in rabbits

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    Marcello Colombo-Barboza

    2014-10-01

    Full Text Available Objective: To evaluate the effect of riboflavin-ultraviolet-A-induced cross-linking (CXL following corneal alkali burns in rabbits. Methods: The right corneas and limbi of ten rabbits were burned using a 1N solution of NaOH and the animals were then divided into two groups: a control group submitted to clinical treatment alone and an experimental group that was treated 1 h after injury with CXL, followed by the same clinical treatment as administered to the controls. Clinical parameters were evaluated post-injury at 1, 7, 15, and 30 days by two independent observers. Following this evaluation, the corneas were excised and examined histologically. Results: There were no statistically significant differences in clinical parameters, such as hyperemia, corneal edema, ciliary injection, limbal ischemia, secretion, corneal neovascularization, symblepharon, or blepharospasm, at any of the time-points evaluated. However, the size of the epithelial defect was significantly smaller in the CXL group (p<0.05 (day 15: p=0.008 and day 30: p=0.008 and the extent of the corneal injury (opacity lesion was also smaller (day 30: p=0.021. Histopathology showed the presence of collagen bridges linking the collagen fibers in only the CXL group. Conclusions: These results suggest that the use of CXL may improve the prognosis of acute corneal alkali burns.

  4. Intraoperative corneal thickness measurements during corneal collagen cross-linking with isotonic riboflavin solution without dextran in corneal ectasia.

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    Cınar, Yasin; Cingü, Abdullah Kürşat; Sahin, Alparslan; Türkcü, Fatih Mehmet; Yüksel, Harun; Caca, Ihsan

    2014-03-01

    Abstract Objective: To monitor the changes in corneal thickness during the corneal collagen cross-linking procedure by using isotonic riboflavin solution without dextran in ectatic corneal diseases. The corneal thickness measurements were obtained before epithelial removal, after epithelial removal, following the instillation of isotonic riboflavin solution without dextran for 30 min, and after 10 min of ultraviolet A irradiation. Eleven eyes of eleven patients with progressive keratoconus (n = 10) and iatrogenic corneal ectasia (n = 1) were included in this study. The mean thinnest pachymetric measurements were 391.82 ± 30.34 µm (320-434 µm) after de-epithelialization of the cornea, 435 ± 21.17 µm (402-472 µm) following 30 min instillation of isotonic riboflavin solution without dextran and 431.73 ± 20.64 µm (387-461 µm) following 10 min of ultraviolet A irradiation to the cornea. Performing corneal cross-linking procedure with isotonic riboflavin solution without dextran might not induce corneal thinning but a little swelling throughout the procedure.

  5. Corneal collagen cross-linking and liposomal amphotericin B combination therapy for fungal keratitis in rabbits

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    Zhao-Qin Hao

    2016-11-01

    Full Text Available AIM: To observe the therapeutic effect of corneal collagen cross-linking (CXL in combination with liposomal amphotericin B in fungal corneal ulcers. METHODS: New Zealand rabbits were induced fungal corneal ulcers by scratching and randomly divided into 3 groups, i.e. control, treated with CXL, and combined therapy of CXL with 0.25% liposomal amphotericin B (n=5 each. The corneal lesions were documented with slit-lamp and confocal microscopy on 3, 7, 14, 21 and 28d after treatment. The corneas were examined with transmission electron microscopy (TEM at 4wk. RESULTS: A rabbit corneal ulcer model of Fusarium was successfully established. The corneal epithelium defect areas in the two treatment groups were smaller than that in the control group on 3, 7, 14 and 21d (P<0.05. The corneal epithelium defect areas of the combined group was smaller than that of the CXL group (P<0.05 on 7 and 14d, but there were no statistical differences on 3, 21 and 28d. The corneal epithelium defects of the two treatment groups have been healed by day 21. The corneal epithelium defects of the control group were healed on 28d. The diameters of the corneal collagen fiber bundles (42.960±7.383 nm in the CXL group and 37.040±4.160 nm in the combined group were thicker than that of the control group (24.900±1.868 nm, but there was no difference between the two treatment groups. Some corneal collagen fiber bundles were distorted and with irregular arrangement, a large number of fibroblasts could be seen among them but no inflammatory cells in both treatment groups. CONCLUSION: CXL combined with liposomal amphotericin B have beneficial effects on fungal corneal ulcers. The combined therapy could alleviate corneal inflammattions, accelerate corneal repair, and shorten the course of disease.

  6. Evaluation of subbasal nerve morphology and corneal sensation after accelerated corneal collagen cross-linking treatment on keratoconus.

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    Ozgurhan, Engin Bilge; Celik, Ugur; Bozkurt, Ercument; Demirok, Ahmet

    2015-05-01

    The aim of this study was to report on the evaluation of corneal nerve fiber density and corneal sensation after accelerated corneal collagen cross-linking on keratoconus patients. The study was performed on 30 keratoconus eyes (30 participants: 16 M, 14 F; 17-32 years old) treated with accelerated collagen cross-linking for disease stabilization. Mean outcome measures were corneal sensation evaluation by Cochet-Bonnet esthesiometry and subbasal nerve fiber density assessment by corneal in vivo confocal microscopy. All corneal measurements were performed using scanning slit confocal microscopy (ConfoScan 4, Nidek Technologies, Padova, Italy). The accelerated corneal collagen cross-linking procedure was performed on 30 eyes of 30 patients (19 right, 63.3%; 11 left, 27.7%). The mean age was 23.93 ± 4. The preoperative mean keratometry, apex keratometry and pachymetry values were 47.19 ± 2.82 D, 56.79 ± 5.39 and 426.1 ± 25.6 μm, respectively. Preoperative mean corneal sensation was 56.3 ± 5.4 mm (with a range from 40 to 60 mm), it was significantly decreased at 1st and 3rd month visit and increased to preoperative values after 6th month visit. Preoperative mean of subbasal nerve fiber density measurements was 22.8 ± 9.7 nerve fiber/mm(2) (with a range of 5-45 mm), it was not still at the preoperative values at 6th month (p = 0.0001), however reached to the preoperative values at 12th month (p = 0.914). Subbasal nerve fibers could reach the preoperative values at the 12th month after accelerated corneal collagen cross-linking treatment although the corneal sensation was improved at 6th month. These findings imply that the subjective healing process is faster than the objective evaluation of the keratoconus patients' cornea treated with accelerated corneal collagen cross-linking.

  7. Nodular Epithelial Hyperplasia after Photorefractive Keratectomy Followed by Corneal Collagen Cross-Linking

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    Bogoni, Ayla; Salerno, Liberdade Cezaro; Ghanem, Vinícius Coral; Ghanem, Ramon Coral

    2013-01-01

    This study describes a case of nodular epithelial hyperplasia and stromal alterations in a patient with keratoconus who was submitted to topography-guided photorefractive keratectomy (PRK) followed by corneal collagen cross-linking. Debridement of the epithelial nodule was performed. After a 2-year followup, a new topography-guided PRK was indicated.

  8. Riboflavin/UVA Collagen Cross-Linking-Induced Changes in Normal and Keratoconus Corneal Stroma

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    Hayes, Sally; Boote, Craig; Kamma-Lorger, Christina S.; Rajan, Madhavan S.; Harris, Jonathan; Dooley, Erin; Hawksworth, Nicholas; Hiller, Jennifer; Terill, Nick J.; Hafezi, Farhad; Brahma, Arun K.; Quantock, Andrew J.; Meek, Keith M.

    2011-01-01

    Purpose To determine the effect of Ultraviolet-A collagen cross-linking with hypo-osmolar and iso-osmolar riboflavin solutions on stromal collagen ultrastructure in normal and keratoconus ex vivo human corneas. Methods Using small-angle X-ray scattering, measurements of collagen D-periodicity, fibril diameter and interfibrillar spacing were made at 1 mm intervals across six normal post-mortem corneas (two above physiological hydration (swollen) and four below (unswollen)) and two post-transplant keratoconus corneal buttons (one swollen; one unswollen), before and after hypo-osmolar cross-linking. The same parameters were measured in three other unswollen normal corneas before and after iso-osmolar cross-linking and in three pairs of swollen normal corneas, in which only the left was cross-linked (with iso-osmolar riboflavin). Results Hypo-osmolar cross-linking resulted in an increase in corneal hydration in all corneas. In the keratoconus corneas and unswollen normal corneas, this was accompanied by an increase in collagen interfibrillar spacing (priboflavin solutions are more likely a consequence of treatment-induced changes in tissue hydration rather than cross-linking. PMID:21850225

  9. Simultaneous topography-guided PRK followed by corneal collagen cross-linking for keratoconus.

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    Kymionis, George D; Kontadakis, Georgios A; Kounis, George A; Portaliou, Dimitra M; Karavitaki, Alexandra E; Magarakis, Michael; Yoo, Sonia; Pallikaris, Ioannis G

    2009-09-01

    To present the results after simultaneous photorefractive keratectomy (PRK) followed by corneal collagen cross-linking (CXL) for progressive keratoconus. Twelve patients (14 eyes) with progressive keratoconus were prospectively treated with customized topography-guided PRK with the Pulzar Z1 (wavelength 213 nm, CustomVis) immediately followed by corneal collagen CXL with the use of riboflavin and ultraviolet A irradiation. Mean follow-up was 10.69+/-5.95 months (range: 3 to 16 months). Mean preoperative spherical equivalent refraction (SE) was -3.03+/-3.23 diopters (D) and defocus was 4.67+/-3.29 D; at last follow-up SE and defocus were statistically significantly reduced to -1.29+/-2.05 D and 3.04+/-2.53 D, respectively (PPRK followed by CXL seems to be a promising treatment capable of offering functional vision in patients with keratoconus. Copyright 2009, SLACK Incorporated.

  10. Changes in corneal topography and biomechanical properties after collagen cross linking for keratoconus: 1-year results.

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    Sedaghat, Mohammadreza; Bagheri, Mansooreh; Ghavami, Shahri; Bamdad, Shahram

    2015-01-01

    To evaluate changes in corneal topography and biomechanical properties after collagen cross-linking (CXL) for progressive keratoconus. Collagen cross-linking was performed on 97 eyes. We assessed uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA). Corneal topography indices were evaluated using placido disc topography, scanning slit anterior topography (Orbscan II), and rotating Scheimpflug topography (Pentacam). Specular microscopy and corneal biomechanics were evaluated. A 1-year-follow-up results revealed that UCVA improved from 0.31 to 0.45 and BCVA changed from 0.78 to 0.84 (P < 0.001). The mean of average keratometry value decreased from 49.62 to 47.95 D (P < 0.001). Astigmatism decreased from 4.84 to 4.24 D (P < 0.001). Apex corneal thickness decreased from 458.11 to 444.46 μm. Corneal volume decreased from 56.66 to 55.97 mm(3) (P < 0.001). Posterior best fit sphere increased from 55.50 to 46.03 mm (P = 0.025). Posterior elevation increased from 99.2 to 112.22 μm (P < 0.001). Average progressive index increased from 2.26 to 2.56 (P < 0.001). A nonsignificant decrease was observed in mean endothelial count from 2996 to 2928 cell/mm(2) (P = 0.190). Endothelial coefficient of variation (CV) increased nonsignificantly from 18.26 to 20.29 (P = 0.112). Corneal hysteresis changed from 8.18 to 8.36 (P = 0.552) and corneal resistance factor increased from 6.98 to 7.21 (P = 0.202), so these changes were not significant. Visual acuity and K values improved after CXL. In spite of the nonsignificant increase in endothelial cell count and increase in the CV, CLX seems to be a safe treatment for keratoconus. Further studies with larger sample sizes and longer follow-up periods are recommended.

  11. Microbiologic Examination of Bandage Contact Lenses Used after Corneal Collagen Cross-linking Treatment.

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    Yuksel, Erdem; Yalcin, Nuriye Gokçen; Kilic, Gaye; Cubuk, Mehmet Ozgur; Ozmen, Mehmet Cuneyt; Altay, Aylin; Çağlar, Kayhan; Bilgihan, Kamil

    2016-01-01

    To investigate the agents of bacterial contamination of contact lenses after corneal collagen cross-linking (CCL), and to present the possible changes of ocular flora after riboflavin/ultraviolet A. Seventy-two contact lenses of patients who underwent CCL and 41 contact lenses of patients who underwent photorefractive keratectomy (PRK) as control group were enrolled to the study. After 48 h of incubation, broth culture media was transferred to plates. Samples were accepted as positive if one or more colony-forming units were shown. There were positive cultures in 12 (16.7%) contact lenses in the CCL group and 5 (12.2%) had positive cultures in PRK group. Coagulase-negative staphlycocci (CNS) were the most frequent microorganism. Alpha hemolytic streptococci and Diphteroid spp. were the other isolated microorganisms. Bacterial colonization can occur during and early after the CCL procedure in epithelial healing. To prevent corneal infections after the treatment, prophylactic antibiotics should be prescribed.

  12. Corneal-Wavefront guided transepithelial photorefractive keratectomy after corneal collagen cross linking in keratoconus

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    Massimo Camellin

    2017-01-01

    Conclusions: Corneal-Wavefront guided transepithelial PRK ablation profiles after conventional CXL yields to good visual, optical, and refractive results. These treatments are safe and efficacious for the correction of refracto-therapeutic problems in keratoconic patients.

  13. Corneal changes following collagen cross linking and simultaneous topography guided photoablation with collagen cross linking for keratoconus

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    Prema Padmanabhan

    2014-01-01

    Full Text Available Purpose: To compare the outcome of Collagen cross-linking (CXL with that following topography-guided customized ablation treatment (T-CAT with simultaneous CXL in eyes with progressive keratoconus. Materials and Methods: This was a prospective, non-randomized single centre study of 66 eyes with progressive keratoconus. Of these, 40 eyes underwent CXL and 26 eyes underwent T-CAT + CXL. The refractive, topographic, tomographic and aberrometric changes measured at baseline, 1, 3 and 6 months post-operatively were compared between both groups. Results: After a mean follow-up of 7.7 ± 1.3 months, the mean retinoscopic cylinder decreased by 1.02 ± 3.16 D in the CXL group ( P = 0.1 and 2.87 ± 3.22 D in the T-CAT + CXL group ( P = 0.04. The Best corrected visual acuity increased by 2 lines or more in 10% of eyes in the CXL group and in 23.3% of eyes in the T-CAT + CXL group. The mean steepest-K reduced by 0.40 ± 3.71 D ( P = 0.77 in the CXL group and by 2.91 ± 2.01D ( P = 0.03 in the T-CAT + CXL group. The sag factor and surface asymmetry index showed no significant change in the CXL group but reduced by 3.59 ± 5.94 D ( P = 0.01 and 0.72 ± 1.18 ( P = 0.02 respectively in the T-CAT + CXL group. There was a significant increase in the highest posterior corneal elevation in both groups (9.57 ± 14.93 μ in the CXL group and 7.85 ± 9.25 μ in the T-CAT + CXL group, P ≤ 0.001 for both. There was significantly greater reduction of mean coma ( P < 0.001 and mean higher-order aberrations ( P = 0.01 following T-CAT + CXL compared to CXL. Conclusions: CAT + CXL is an effective approach to confer biomechanical stability and to improve the corneal contour in eyes with keratoconus and results in better refractive, topographic and aberrometric outcomes than CXL alone.

  14. Orbscan II anterior elevation changes following corneal collagen cross-linking treatment for keratoconus.

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    Tu, Kyaw Lin; Aslanides, Ioannis M

    2009-08-01

    To analyze anterior corneal elevation changes on Orbscan II following corneal collagen cross-linking (CXL) with riboflavin. This retrospective study included 8 patients (14 eyes) with keratoconus who underwent CXL, with a mean follow-up of 7 months (range: 5 to 10 months). Pre- and postoperative (at last clinic attendance) anterior elevation difference maps were examined for overall patterns of change. On preoperative maps, distances from maximum anterior elevation to pupil center and to topographic geometric center were compared between the two patterns identified. Pre- and postoperative topography, best spectacle-corrected visual acuity (BSCVA), and refraction were also compared between the two patterns. Two patterns of anterior elevation change were visually identified: (1) paracentral steepening, no change, or flattening centrally; and (2) central steepening. The preoperative maps of eyes that manifested pattern 1 had shorter mean distances for maximum anterior elevation to pupil center (1.70 vs. 2.27 mm) and maximum anterior elevation to geometric center (1.45 vs. 1.99 mm) than those that resulted in pattern 2. Mean maximum topographic simulated keratometry decreased (P = .004) and mean irregularity indices at 3 mm (P =.03) and 5 mm (P =.04) were reduced postoperatively in pattern 1 eyes; all increased in pattern 2 eyes. Mean BSCVA improved postoperatively for both patterns. Mean preoperative myopia decreased in pattern 1 eyes by 0.44 diopters (D), whereas it increased for pattern 2 eyes by 1.83 D. Corneal shape change influenced by anisotropy of collagen distribution is a factor in the outcome of CXL treatment for keratoconus.

  15. Role of corneal collagen fibrils in corneal disorders and related pathological conditions

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    Hong-Yan Zhou

    2017-05-01

    Full Text Available The cornea is a soft tissue located at the front of the eye with the principal function of transmitting and refracting light rays to precisely sense visual information. Corneal shape, refraction, and stromal stiffness are to a large part determined by corneal fibrils, the arrangements of which define the corneal cells and their functional behaviour. However, the modality and alignment of native corneal collagen lamellae are altered in various corneal pathological states such as infection, injury, keratoconus, corneal scar formation, and keratoprosthesis. Furthermore, corneal recuperation after corneal pathological change is dependent on the balance of corneal collagen degradation and contraction. A thorough understanding of the characteristics of corneal collagen is thus necessary to develop viable therapies using the outcome of strategies using engineered corneas. In this review, we discuss the composition and distribution of corneal collagens as well as their degradation and contraction, and address the current status of corneal tissue engineering and the progress of corneal cross-linking.

  16. Corneal Absorption of a New Riboflavin-Nanostructured System for Transepithelial Collagen Cross-Linking

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    Bottos, Katia M.; Oliveira, Anselmo G.; Bersanetti, Patrícia A.; Nogueira, Regina F.; Lima-Filho, Acácio A. S.; Cardillo, José A.; Schor, Paulo; Chamon, Wallace

    2013-01-01

    Corneal collagen cross-linking (CXL) has been described as a promising therapy for keratoconus. According to standard CXL protocol, epithelium should be debrided before treatment to allow penetration of riboflavin into the corneal stroma. However, removal of the epithelium can increase procedure risks. In this study we aim to evaluate stromal penetration of a biocompatible riboflavin-based nanoemulsion system (riboflavin-5-phosphate and riboflavin-base) in rabbit corneas with intact epithelium. Two riboflavin nanoemulsions were developed. Transmittance and absorption coefficient were measured on corneas with intact epithelia after 30, 60, 120, 180, and 240 minutes following exposure to either the nanoemulsions or standard 0.1% or 1% riboflavin-dextran solutions. For the nanoemulsions, the epithelium was removed after measurements to assure that the riboflavin had passed through the hydrophobic epithelium and retained within the stroma. Results were compared to de-epithelialized corneas exposed to 0.1% riboflavin solution and to the same riboflavin nanoemulsions for 30 minutes (standard protocol). Mean transmittance and absorption measured in epithelialized corneas receiving the standard 0.1% riboflavin solution did not reach the levels found on the debrided corneas using the standard technique. Neither increasing the time of exposure nor the concentration of the riboflavin solution from 0.1% to 1% improved riboflavin penetration through the epithelium. When using riboflavin-5-phosphate nanoemulsion for 240 minutes, we found no difference between the mean absorption coefficients to the standard cross-linking protocol (p = 0.54). Riboflavin nanoemulsion was able to penetrate the corneal epithelium, achieving, after 240 minutes, greater stromal concentration when compared to debrided corneas with the standard protocol (p = 0.002). The riboflavin-5-phosphate nanoemulsion diffused better into the stroma than the riboflavin-base nanoemulsion. PMID:23785497

  17. Corneal Collagen Cross-Linking with Hypoosmolar Riboflavin Solution in Keratoconic Corneas

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    Shaofeng Gu

    2014-01-01

    Full Text Available Purpose. To report the 12-month outcomes of corneal collagen cross-linking (CXL with a hypoosmolar riboflavin and ultraviolet-A (UVA irradiation in thin corneas. Methods. Eight eyes underwent CXL using a hypoosmolar riboflavin solution after epithelial removal. The corrected distance visual acuity (CDVA, manifest refraction, the mean thinnest corneal thickness (MTCT, and the endothelial cell density (ECD were evaluated before and 6 and 12 months after CXL. Results. The MTCT was 413.9 ± 12.4 μm before treatment and reduced to 381.1 ± 7.3 μm after the removal of the epithelium. After CXL, the thickness decreased to 410.3 ± 14.5 μm at the last follow-up. Before treatment, the mean K-value of the apex of the keratoconus corneas was 58.7 ± 3.5 diopters and slightly decreased (57.7 ± 4.9 diopters at 12 months. The mean CDVA was 0.54 ± 0.23 logarithm of the minimal angle of resolution before treatment and increased to 0.51 ± 0.21 logarithm at the last follow-up. The ECD was 2731.4 ± 191.8 cells/mm2 before treatment and was 2733.4 ± 222.6 cells/mm2 at 12 months after treatment. Conclusions. CXL with a hypoosmolar riboflavin in thin corneas seems to be a promising method for keratoconic eyes with the mean thinnest corneal thickness less than 400 μm without epithelium.

  18. Protein Oxidation Levels After Different Corneal Collagen Cross-Linking Methods.

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    Turkcu, Ummuhani Ozel; Yuksel, Nilay; Novruzlu, Sahin; Yalinbas, Duygu; Bilgihan, Ayse; Bilgihan, Kamil

    2016-03-01

    To evaluate advanced oxidation protein products (AOPP) levels, superoxide dismutase (SOD) enzyme activity, and total sulfhydryl (TSH) levels in rabbit corneas after different corneal collagen cross-linking (CXL) methods. Eighteen eyes of 9 adult New Zealand rabbits were divided into 3 groups of 6 eyes. The standard CXL group was continuously exposed to UV-A at a power setting of 3 mW/cm for 30 minutes. The accelerated CXL (A-CXL) group was continuously exposed to UV-A at a power setting of 30 mW/cm for 3 minutes. The pulse light-accelerated CXL (PLA-CXL) group received UV-A at a power setting of 30 mW/cm for 6 minutes of pulsed exposure (1 second on, 1 second off). Corneas were obtained after 1 hour of UV-A exposure, and 360-degree keratotomy was performed. SOD enzyme activity, AOPP, and TSH levels were measured in the corneal tissues. Compared with the standard CXL and A-CXL groups (133.2 ± 8.5 and 140.2 ± 6.2 μmol/mg, respectively), AOPP levels were found to be significantly increased in the PLA-CXL group (230.7 ± 30.2 μmol/mg) (P = 0.005 and 0.009, respectively). SOD enzyme activities and TSH levels did not differ between the groups (P = 0.167 and 0.187, respectively). CXL creates covalent bonds between collagen fibers because of reactive oxygen species. This means that more oxygen concentration during the CXL method will produce more reactive oxygen species and, thereby, AOPP. This means that in which CXL method occurs in more oxygen concentration that will produce more reactive oxygen species and thereby AOPP. This study demonstrated that PLA-CXL results in more AOPP formation than did standard CXL and A-CXL.

  19. Corneal collagen cross-linking in the stabilization of PRK, LASIK, thermal keratoplasty, and orthokeratology.

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    Nguyen, Michelle K; Chuck, Roy S

    2013-07-01

    To describe the use of corneal collagen cross-linking (CXL) and its efficacy in the stabilization of keratorefractive procedures, including PRK, laser in-situ keratomileusis (LASIK), thermal keratoplasty, and orthokeratology. Since its introduction, CXL has quickly gained interest in the treatment of ectactic disorders due to its ability to increase the biomechanical stability of the cornea. In its earliest use, it has shown to be effective in the treatment of both keratoconus and post-LASIK ectasia. More recent studies of CXL in combination with keratorefractive procedures have shown varying degrees of success. CXL with PRK has shown to be effective in slowing or halting the progression of keratoconus, pellucid marginal degeneration, and post-LASIK ectasia, in addition to potentially decreasing or delaying the need for penetrating keratoplasty. Several small case series have also demonstrated improved stability and efficacy of PRK and LASIK when combined with CXL, as well as a potentially decreased risk of postprocedure ectasia. In conjunction with thermokeratoplasty and orthokeratology, CXL has shown improved but only temporary results in the treatment of keratoconus. Future studies are needed to determine the efficacy and long-term stability of CXL in combination with keratorefractive procedures, as well as to address possible complications.

  20. Treatment Results of Corneal Collagen Cross-Linking Combined with Riboflavin and 440 Nm Blue Light for Bacterial Corneal Ulcer in Rabbits.

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    Wei, Shufang; Zhang, Cuiying; Zhang, Shaoru; Xu, Yanyun; Mu, Guoying

    2017-10-01

    To study the treatment effect of corneal collagen cross-linking (CXL) combined with 440 nm blue light and riboflavin on bacterial corneal ulcer using animal experiments. A total of 21 New Zealand white rabbits that developed Staphylococcus aureus corneal ulcer were randomly divided into three groups. Seven rabbits were used as blank control groups; seven rabbits were treated with CXL combined with riboflavin and 440 nm blue light; and seven rabbits were treated with CXL combined with riboflavin and 370 nm ultraviolet A light. Necrotic tissues or secretions from the ulcer surface, eye secretions, conjunctival hyperemia, hypopyon, corneal infiltration, and pathological changes of the cornea were all observed. The 1st, 3th, and 7th day after CXL treatment, a statistically significant difference was found among the inflammation scores of the three groups. The scores of 440 and 370 groups decreased gradually, significantly lower than that of the control group. Bacterial cultures of 440 and 370 groups turned to be negative while that of the control group remained positive. After 1 day of CXL treatment, pathology pictures of the three groups all showed loss of corneal epithelia with many inflammatory cells in deep stroma. After 7 days of CXL treatment, abscess formed in almost all corneal area in the control group, while in 440 and 370 groups, multilayer healing of corneal epithelia, neovascularization, and many inflammatory cells within ulcers and proliferation of a small amount of fibroblast were seen. CXL combined with riboflavin and 440 nm blue light is effective in treating S. aureus corneal ulcer.

  1. Comparison of Aqueous Humor Nitric Oxide Levels After Different Corneal Collagen Cross-Linking Methods.

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    Yuksel, Nilay; Ozel-Turkcu, Ummuhani; Yalinbas, Duygu; Novruzlu, Sahin; Bilgihan, Ayse; Bilgihan, Kamil

    2016-12-01

    Nitric oxide production can cause either apoptotic or necrotic cell death through oxidative stress. We aimed to investigate the nitrite oxide metabolites (NO x ) and nitrite levels in the aqueous humor of rabbit eyes after different methods of corneal collagen cross-linking (CXL). Twenty-four eyes of 12 adult New Zealand rabbits were used. They were assigned into four groups, each including six eyes. Group 1 (control) consisted of eyes with no treatment. Group 2 received UV-A power setting at 3 mW/cm 2 for 30 minutes of continuous exposure and named as standard CXL group. Group 3 received UV-A power setting at 30 mW/cm 2 for 3 minutes of continuous exposure and named as accelerated CXL (A-CXL) group. Group 4 received UV-A power setting at 30 mW/cm 2 for 6 minutes of pulsed exposure (1 sec on, 1 sec off) and named as pulse-light accelerated CXL (PLA-CXL). Aqueous humors were aspirated from anterior chamber with a 27G needle after 1 hour UV-A exposure. NO x and nitrite levels were measured Results: The nitrite levels in aqueous humor were significantly increased in Group 2 and Group 3 when compared with Group 1 (p = 0.000, p = 0.036, respectively). When treatment modalities were compared with each other, high nitrite level in Group 2 was statistically significant when compared with Group 4 (p = 0.019). NO x levels were higher in Group 2 when compared with Group 1 (p = 0.006). Numerous studies investigated the physiological and pathophysiological roles of NO. NO is considered one of the most important molecule for ocular health. According to NO x level in aqueous humor, it seems that PLA-CXL is the safest method due to the similar results with control group.

  2. Corneal thickness changes during corneal collagen cross-linking with UV-A irradiation and hypo-osmolar riboflavin in thin corneas

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    Belquiz Amaral Nassaralla

    2013-06-01

    Full Text Available PURPOSE: To evaluate the thinnest corneal thickness changes during and after corneal collagen cross-linking treatment with ultraviolet-A irradiation, using hypo-osmolar riboflavin solution in thin corneas. METHODS: Eighteen eyes of 18 patients were included in this study. After epithelium removal, iso-osmolar 0.1% riboflavin solution was instilled to the cornea every 3 minutes for 30 minutes. Hypo-osmolar 0.1% riboflavin solution was then applied every 20 seconds for 5 minutes or until the thinnest corneal thickness reached 400 µm. Ultraviolet-A irradiation was performed for 30 minutes. During irradiation, iso-osmolar 0.1% riboflavin drops were applied every 5 minutes. Ultrasound pachymetry was performed at approximately the thinnest point of the cornea preoperatively, after epithelial removal, after iso-osmolar riboflavin instillation, after hypo-osmolar riboflavin instillation, after ultraviolet-A irradiation, and at 1, 6 and 12 months after treatment. RESULTS: Mean preoperative thinnest corneal thickness was 380 ± 11 µm. After epithelial removal it decreased to 341 ± 11 µm, and after 30 minutes of iso-osmolar 0.1% riboflavin drops, to 330 ± 7.6 µm. After hypo-osmolar 0.1% riboflavin drops, mean thinnest corneal thickness increased to 418 ± 11 µm. After UVA irradiation, it was 384 ± 10 µm. At 1, 6 and 12 months after treatment, it was 372 ± 10 µm, 381 ± 12.7, and 379 ± 15 µm, respectively. No intraoperative, early postoperative, or late postoperative complications were noted. CONCLUSIONS: Hypo-osmolar 0.1% riboflavin solution seems to be effective for swelling thin corneas. The swelling effect is transient and short acting. Corneal thickness should be monitored throughout the procedure. Larger sample sizes and longer follow-up are required in order to make meaningful conclusions regarding safety.

  3. Herpetic keratitis after corneal collagen cross-linking with riboflavin and ultraviolet-A for progressive keratoconus.

    Science.gov (United States)

    Yuksel, Nilay; Bilgihan, Kamil; Hondur, Ahmet M

    2011-12-01

    To describe a case of herpetic keratitis after corneal collagen cross-linking (CXL) with riboflavin and ultraviolet-A for progressive keratoconus. A 31-year-old woman with rapidly progressive keratoconus in the left eye was treated with CXL. Four days postoperatively, a dendritic ulcer developed in the treated eye. The diagnosis was confirmed with polymerase chain reaction analysis of the corneal swab for herpes simplex. The patient had no prior history of herpetic eye disease or cold sores. The keratitis resolved in 10 days with treatment. At 1 month, the visual acuity was stable, but a mild superficial opacity was noted. Herpetic keratitis can be induced by CXL even in patients with no history of previous herpetic eye disease. Early diagnosis and proper treatment can facilitate successful management of this rare but important complication.

  4. Microbiologic, Pharmacokinetic, and Clinical Effects of Corneal Collagen Cross-Linking on Experimentally Induced Pseudomonas Keratitis in Rabbits.

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    Cosar, C Banu; Kucuk, Mutlu; Celik, Ekrem; Gonen, Tansu; Akyar, Isin; Serteser, Mustafa; Tokat, Fatma; Ince, Umit

    2015-10-01

    To determine the effects of corneal collagen cross-linking (CXL) on the penetration of topical 0.5% moxifloxacin, on the number of colony-forming units (CFUs) in the cornea, and on the clinical course in a rabbit eye model of experimentally induced Pseudomonas aeruginosa keratitis. In this prospective animal study, experimental Pseudomonas corneal ulcers were induced in 56 corneas of 28 albino New Zealand rabbits. The corneas were randomly divided into the following 4 groups: the control group (14 eyes), the MOX group (moxifloxacin) (14 eyes), the MOX + CXL group (14 eyes), and the CXL group (14 eyes). On day 4 of the experiment, the eyes in the control group were enucleated and CFU counting was performed. On day 10 of the experiment, all eyes were enucleated and CFU counting was performed. In the MOX and MOX + CXL groups, the moxifloxacin level in the cornea, aqueous humor, iris, plasma, and serum was measured by reverse-phase high-performance liquid chromatography. The difference in the corneal CFU count between the MOX group and the MOX + CXL group was not significant (P = 0.317). Clinical improvement was greatest in the MOX + CXL group (P < 0.001). The mean corneal moxifloxacin level was 0.391 ± 0.09 μg·mg in the MOX group versus 0.291 ± 0.09 μg·mg in the MOX + CXL group; as such, CXL did not have a significant effect on antibiotic penetrance (P = 0.386). Clinical improvement was greatest in the MOX + CXL group. The synergistic effect of CXL on corneal ulcer treatment is not through antibiotic penetrance.

  5. Management of pediatric keratoconus - Evolving role of corneal collagen cross-linking: An update

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    Vardhaman P Kankariya

    2013-01-01

    Full Text Available Pediatric keratoconus demonstrates several distinctive management issues in comparison with adult keratoconus with respect to under-diagnosis, poor compliance and modifications in treatment patterns. The major concerns comprise of the accelerated progression of the disease in the pediatric age group and management of co-morbidities such as vernal keratoconjuntivitis. Visual impairment in pediatric patients may affect social and educational development and overall negatively impact their quality of life. The treatment algorithm between adults and pediatric keratoconus has been similar; comprising mainly of visual rehabilitation with spectacles, contacts lenses (soft or rigid and keratoplasty (lamellar or penetrating depending on the stage of the disease. There is a paradigm shift in the management of keratoconus, a new treatment modality, corneal collagen crosslinking (CXL, has been utilized in adult keratoconic patients halting the progression of the disease. CXL has been utilized for over a 10 year period and based on the evidence of efficacy and safety in the adult population; this treatment has been recently utilized in management of pediatric keratoconus. This article will present an update about current management of pediatric keratoconus with special focus on CXL in this age group.

  6. Corneal collagen cross-linking with riboflavin and ultraviolet - A light for keratoconus: Results in Indian eyes

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    Agrawal Vinay

    2009-01-01

    Full Text Available Aim: To assess the results of corneal collagen cross-linking with riboflavin using ultraviolet - A light for keratoconus at one year in Indian eyes. Materials and Methods: Sixty-eight eyes of 41 patients with progressive keratoconus were included in this retrospective study. All eyes completed was 12 months of follow-up and 37 eyes had a one-year follow-up. The maximum follow-up was 16 months. Ocular examinations including refraction, best corrected visual acuity (BCVA, corneal topography, were recorded at each visit. Results: The mean age was 16.9 ± 3.5 years (range 12-39 years and the mean follow-up was 10.05 ± 3.55 months (range six to 16 months. Thirty seven eyes with a follow-up of at least 12 months were analyzed. The preoperative values on the day of treatment were compared with postoperative values of the 12-month examination. This showed that BCVA improved at least one line in 54% (20/37 of eyes and remained stable in 28% (10/37 of eyes ( P =0.006. Astigmatism decreased by a mean of 1.20 diopter (D in 47% (17/37 of eyes ( P =0.005 and remained stable (within ± 0.50 D in 42% (15/37 of eyes. The K value of the apex decreased by a mean of 2.73 D in 66% (24/37 of eyes ( P =0.004 and remained stable (within ± 0.50 D in 22% (8/37 of eyes. The maximum K value decreased by a mean of 2.47 D in 54% (20/37 of eyes ( P =0.004 and remained stable (within ± 0.50 D in 38% (14/37 of eyes. Corneal Wavefront analysis revealed that spherical and higher-order aberrations did not show significant variations in the follow-up period. The coma component showed a very significant reduction at six months after treatment and persisted throughout the follow-up period ( P =0.003 Conclusion: The results show a stabilization and improvement in keratoconus after collagen cross-linking in Indian eyes. This suggests that it is an effective treatment for progressive keratoconus.

  7. Comparison of Changes in Central Corneal Thickness During Corneal Collagen Cross-Linking, Using Isotonic Riboflavin Solutions With and Without Dextran, in the Treatment of Progressive Keratoconus.

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    Zaheer, Naima; Khan, Wajid Ali; Khan, Shama; Khan, M Abdul Moqeet

    2018-03-01

    To compare intraoperative changes in central corneal thickness (CCT) during corneal cross-linking, using 2 different isotonic riboflavin solutions either with dextran or with hydroxy propyl methylcellulose, in the treatment of progressive keratoconus. In this retrospective study, we analyzed records of corneal thickness measurements, taken during various steps of cross-linking. Cross-linking was performed using either isotonic riboflavin with dextran (group A) or isotonic riboflavin with hydroxy propyl methylcellulose (without dextran) (group B). CCT measurements were recorded before and after epithelial removal, after saturation with respective isotonic riboflavin solution, after use of hypotonic riboflavin in selected cases, and after ultraviolet A (UV-A) application. A mixed-way analysis of variance was conducted on CCT readings within each group and between both groups, and p dextran causes a significant decrease in corneal thickness, whereas dextran-free isotonic riboflavin causes a significant increase in corneal thickness, thus facilitating the procedure.

  8. Accelerated corneal collagen cross-linking in pediatric keratoconus: One year study

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    Amani E. Badawi

    2017-01-01

    Conclusion: Accelerated CXL shows a stabilization and beneficial clinical outcomes in pediatric keratoconus. It seems an effective and safe procedure in this age group. Effects of accelerated CXL on the posterior corneal surface will need further evaluation.

  9. A case report of central toxic keratopathy in a patient post TransPRK (followed by corneal collagen cross-linking).

    Science.gov (United States)

    Davey, Nicholas; Aslanides, Ioannis M; Selimis, Vasilis

    2017-01-01

    The purpose of this article is to report a case of central toxic keratopathy in a patient post transepithelial photorefractive keratectomy (TransPRK), followed immediately by corneal collagen cross-linking. This article describes the case of a 26-year-old male after bilateral aberration-free, TransPRK laser (Schwind Amaris 750S). The procedure was performed for compound myopic astigmatism in November 2015, followed immediately by accelerated corneal collagen cross-linking for early keratoconus. From day 3 post-op, tear film debris underneath both contact lenses with corneal haze and early, progressive central anterior stromal opacity formation only in the left eye were noted. At 2 weeks post-op, the left eye was noted to have a significant hyperopic shift with central corneal thinning in the anterior stroma. A central anterior stromal dense opacity had formed in the left eye with the surrounding superficial stromal haze. As of month 2, the opacity gradually started to improve in size and density. The hyperopic shift peaked at 2 months and continued to improve, largely due to epithelial compensation with a gradual recovery of stromal thickness. The question remains as to what provokes the typical central corneal necrosis/thinning in central toxic keratopathy. We hypothesize that the space between the contact lens and the corneal surface post TransPRK is prone to a "pseudo-interface pathology" that could mimic diffuse lamellar keratitis-like pathology. Suboptimal lid hygiene, resulting in tear film combinations of bacteria, inflammatory cells, matrix metalloproteinases and other proteolytic enzymes, contributes to the degradation of vulnerable, exposed collagen stromal tissue post TransPRK or any surface corneal ablation. Refractive surgeons should maintain a healthy lid margin and tear film, especially in contact lens wearers, to prevent potential complications in refractive surgery procedures.

  10. Management of corneal ectasia after LASIK with combined, same-day, topography-guided partial transepithelial PRK and collagen cross-linking: the athens protocol.

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    Kanellopoulos, Anastasios John; Binder, Perry S

    2011-05-01

    To evaluate a series of patients with corneal ectasia after LASIK that underwent the Athens Protocol: combined topography-guided photorefractive keratectomy (PRK) to reduce or eliminate induced myopia and astigmatism followed by sequential, same-day ultraviolet A (UVA) corneal collagen cross-linking (CXL). Thirty-two consecutive corneal ectasia cases underwent transepithelial PRK (WaveLight ALLEGRETTO) immediately followed by CXL (3 mW/cm(2)) for 30 minutes using 0.1% topical riboflavin sodium phosphate. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent, keratometry, central ultrasonic pachymetry, corneal tomography (Oculus Pentacam), and endothelial cell counts were analyzed. Mean follow-up was 27 months (range: 6 to 59 months). Twenty-seven of 32 eyes had an improvement in UDVA and CDVA of 20/45 or better (2.25 logMAR) at last follow-up. Four eyes showed some topographic improvement but no improvement in CDVA. One of the treated eyes required a subsequent penetrating keratoplasty. Corneal haze grade 2 was present in 2 eyes. Combined, same-day, topography-guided PRK and CXL appeared to offer tomographic stability, even after long-term follow-up. Only 2 of 32 eyes had corneal ectasia progression after the intervention. Seventeen of 32 eyes appeared to have improvement in UDVA and CDVA with follow-up >1.5 years. This technique may offer an alternative in the management of iatrogenic corneal ectasia. Copyright 2011, SLACK Incorporated.

  11. A short-term study of corneal collagen cross-linking with hypo-osmolar riboflavin solution in keratoconic corneas

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    Shao-Feng Gu

    2015-02-01

    Full Text Available AIM: To report the 3mo outcomes of collagen cross-linking (CXL with a hypo-osmolar riboflavin in thin corneas with the thinnest thickness less than 400 μm without epithelium. METHODS: Eight eyes in 6 patients with age 26.2±4.8y were included in the study. All patients underwent CXL using a hypo-osmolar riboflavin solution after its de-epithelization. Best corrected visual acuity, manifest refraction, the thinnest corneal thickness, and endothelial cell density were evaluated before and 3mo after the procedure. RESULTS: The mean thinnest thickness of the cornea was 408.5±29.0 μm before treatment and reduced to 369.8±24.8 μm after the removal of epithelium. With the application of the hypo-osmolar riboflavin solution, the thickness increased to 445.0±26.5 μm before CXL and recover to 412.5±22.7 μm at 3mo after treatment, P=0.659. Before surgery, the mean K-value of the apex of the keratoconus corneas was 57.6±4.0 diopters, and slightly decreased (54.7±4.9 diopters after surgery (P=0.085. Mean best-corrected visual acuity was 0.55±0.23 logarithm of the minimal angle of resolution, and increased to 0.53±0.26 logarithm after surgery (P=0.879. The endothelial cell density was 2706.4±201.6 cells/mm2 before treatment, and slightly decreased (2641.2±218.2 cells/mm2 at last fellow up (P=0.002. CONCLUSION: Corneal collagen cross-linking with a hypo-osmolar riboflavin in thin corneas seems to be a promising treatment. Further study should be done to evaluate the safety and efficiency of CXL in thin corneas for the long-term.

  12. Simultaneous topography-guided PRK followed by corneal collagen cross-linking after lamellar keratoplasty for keratoconus

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    Spadea L

    2012-11-01

    Full Text Available Leopoldo Spadea,1 Marino Paroli21University of L’Aquila, Department of Biotechnological and Applied Clinical Sciences, Eye Clinic, L’Aquila, 2La Sapienza University, Department of Biotechnology and Medical-Surgical Sciences, Latina, ItalyBackground: The purpose of this paper is to report the results of using combined treatment of customized excimer laser-assisted photorefractive keratectomy (PRK and prophylactic corneal collagen crosslinking (CXL for residual refractive error in a group of patients who had previously undergone lamellar keratoplasty for keratoconus.Methods: The study included 14 eyes from 14 patients who had originally been treated for keratoconus in one eye by excimer laser-assisted lamellar keratoplasty (ELLK, and subsequently presented with residual ametropia (-6.11 D ± 2.48, range -2.50 to -9.50. After a mean 40.1 ± 12.4 months since ELLK they underwent combined simultaneous corneal regularization treatment with topographically guided transepithelial excimer laser PRK (central corneal regularization and corneal CXL induced by riboflavin-ultraviolet A.Results: After a mean 15 ± 6.5 (range 6–24 months, all eyes gained at least one Snellen line of uncorrected distance visual acuity (range 1–10. No patient lost lines of corrected distance visual acuity, and four patients gained three lines of corrected distance visual acuity. Mean manifest refractive spherical equivalent was -0.79 ± 2.09 (range +1 to -3.0 D, and topographic keratometric astigmatism was 5.02 ± 2.93 (range 0.8–8.9 D. All the corneas remained clear (haze < 1.Conclusion: The combination of customized PRK and corneal CXL provided safe and effective results in the management of corneal regularization for refractive purposes after ELLK for keratoconus.Keywords: corneal collagen crosslinking, excimer laser-assisted lamellar keratoplasty, photorefractive keratectomy

  13. Simultaneous topography-guided PRK followed by corneal collagen cross-linking after lamellar keratoplasty for keratoconus.

    Science.gov (United States)

    Spadea, Leopoldo; Paroli, Marino

    2012-01-01

    The purpose of this paper is to report the results of using combined treatment of customized excimer laser-assisted photorefractive keratectomy (PRK) and prophylactic corneal collagen crosslinking (CXL) for residual refractive error in a group of patients who had previously undergone lamellar keratoplasty for keratoconus. The study included 14 eyes from 14 patients who had originally been treated for keratoconus in one eye by excimer laser-assisted lamellar keratoplasty (ELLK), and subsequently presented with residual ametropia (-6.11 D ± 2.48, range -2.50 to -9.50). After a mean 40.1 ± 12.4 months since ELLK they underwent combined simultaneous corneal regularization treatment with topographically guided transepithelial excimer laser PRK (central corneal regularization) and corneal CXL induced by riboflavin-ultraviolet A. After a mean 15 ± 6.5 (range 6-24) months, all eyes gained at least one Snellen line of uncorrected distance visual acuity (range 1-10). No patient lost lines of corrected distance visual acuity, and four patients gained three lines of corrected distance visual acuity. Mean manifest refractive spherical equivalent was -0.79 ± 2.09 (range +1 to -3.0) D, and topographic keratometric astigmatism was 5.02 ± 2.93 (range 0.8-8.9) D. All the corneas remained clear (haze PRK and corneal CXL provided safe and effective results in the management of corneal regularization for refractive purposes after ELLK for keratoconus.

  14. Conventional Corneal Collagen Cross-Linking Versus Transepithelial Diluted Alcohol and Iontophoresis-Assisted Corneal Cross-Linking in Progressive Keratoconus.

    Science.gov (United States)

    Bilgihan, Kamil; Yesilirmak, Nilufer; Altay, Yesim; Yuvarlak, Armagan; Ozdemir, Huseyin Baran

    2017-12-01

    To compare clinical outcomes of conventional corneal cross-linking (C-CXL) and diluted alcohol and iontophoresis-assisted corneal cross-linking (DAI-CXL) for the treatment of progressive keratoconus (KC). Ninety-three eyes of 80 patients with KC were treated by C-CXL (n = 47) or DAI-CXL (n = 46). Visual acuity, keratometry, KC indexes, pachymetry, and aberrations were recorded before treatment and 1, 3, 6, and 12 months after treatment. The demarcation line was assessed 1 month after treatment. A significant improvement in visual acuity was observed at month 3 and month 6 after DAI-CXL and C-CXL, respectively. A significant decrease in maximum keratometry was observed in both groups at month 6. The front symmetry index significantly improved in both groups after 6 months, whereas the Baiocchi Calossi Versaci index significantly improved only after DAI-CXL at month 12 (P = 0.01). Average keratometry and other KC indexes were stable during 12 months of follow-up. Central corneal thickness decreased by 28.6 and 40.2 μm after DAI-CXL and C-CXL at month 1, respectively (P < 0.01), and it reached baseline at the 12th month (P = 0.14) only in the DAI-CXL group. Higher-order aberrations, coma, and spherical aberration significantly worsened at month 1 (P < 0.01) only after C-CXL; however, they improved significantly at month 12 compared with baseline (P < 0.05) in both groups. The demarcation line was visible in all cases at month 1 at a mean depth of 302 ± 56 μm and 311 ± 57 μm after DAI-CXL and C-CXL, respectively (P = 0.7). The DAI-CXL protocol seems as effective as the C-CXL protocol in halting KC progression after 1 year of follow-up.

  15. The effect of riboflavin/UVA collagen cross-linking therapy on the structure and hydrodynamic behaviour of the ungulate and rabbit corneal stroma.

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    Sally Hayes

    Full Text Available To examine the effect of riboflavin/UVA corneal crosslinking on stromal ultrastructure and hydrodynamic behaviour.One hundred and seventeen enucleated ungulate eyes (112 pig and 5 sheep and 3 pairs of rabbit eyes, with corneal epithelium removed, were divided into four treatment groups: Group 1 (28 pig, 2 sheep and 3 rabbits were untreated; Group 2 (24 pig were exposed to UVA light (3.04 mW/cm(2 for 30 minutes and Group 3 (29 pig and Group 4 (31 pig, 3 sheep and 3 rabbits had riboflavin eye drops applied to the corneal surface every 5 minutes for 35 minutes. Five minutes after the initial riboflavin instillation, the corneas in Group 4 experienced a 30 minute exposure to UVA light (3.04 mW/cm(2. X-ray scattering was used to obtain measurements of collagen interfibrillar spacing, spatial order, fibril diameter, D-periodicity and intermolecular spacing throughout the whole tissue thickness and as a function of tissue depth in the treated and untreated corneas. The effect of each treatment on the hydrodynamic behaviour of the cornea (its ability to swell in saline solution and its resistance to enzymatic digestion were assessed using in vitro laboratory techniques.Corneal thickness decreased significantly following riboflavin application (p<0.01 and also to a lesser extent after UVA exposure (p<0.05. With the exception of the spatial order factor, which was higher in Group 4 than Group 1 (p<0.01, all other measured collagen parameters were unaltered by cross-linking, even within the most anterior 300 microns of the cornea. The cross-linking treatment had no effect on the hydrodynamic behaviour of the cornea but did cause a significant increase in its resistance to enzymatic digestion.It seems likely that cross-links formed during riboflavin/UVA therapy occur predominantly at the collagen fibril surface and in the protein network surrounding the collagen.

  16. Corneal collagen crosslinking and pigment dispersion syndrome.

    Science.gov (United States)

    LaHood, Benjamin R; Moore, Sacha

    2017-03-01

    We describe the case of a keratoconus patient with pigment dispersion syndrome (PDS) who was treated for progressive corneal ectasia with corneal collagen crosslinking (CXL). Pigment dispersion syndrome has been shown to have associated morphologic changes of the corneal endothelium. Corneal CXL has the potential to cause toxicity to the corneal endothelium, and adjacent pigment might increase the likelihood of damage. In this case, the presence of PDS had no detrimental effect on the outcome of treatment, and no complications were observed at 12 months follow-up, indicating that it may be safe to perform corneal CXL in the setting of PDS. This is an important observation as the number of indications for corneal CXL grows. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  17. A case report of central toxic keratopathy in a patient post TransPRK (followed by corneal collagen cross-linking

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    Davey N

    2017-04-01

    Full Text Available Nicholas Davey, Ioannis M Aslanides, Vasilis Selimis Emmetropia Mediterranean Eye Institute, Heraklion, Crete, Greece Purpose: The purpose of this article is to report a case of central toxic keratopathy in a patient post transepithelial photorefractive keratectomy (TransPRK, followed immediately by corneal collagen cross-linking.Methods: This article describes the case of a 26-year-old male after bilateral aberration-free, TransPRK laser (Schwind Amaris 750S. The procedure was performed for compound myopic astigmatism in November 2015, followed immediately by accelerated corneal collagen cross-linking for early keratoconus.Results: From day 3 post-op, tear film debris underneath both contact lenses with corneal haze and early, progressive central anterior stromal opacity formation only in the left eye were noted. At 2 weeks post-op, the left eye was noted to have a significant hyperopic shift with central corneal thinning in the anterior stroma. A central anterior stromal dense opacity had formed in the left eye with the surrounding superficial stromal haze. As of month 2, the opacity gradually started to improve in size and density. The hyperopic shift peaked at 2 months and continued to improve, largely due to epithelial compensation with a gradual recovery of stromal thickness.Conclusion: The question remains as to what provokes the typical central corneal necrosis/thinning in central toxic keratopathy. We hypothesize that the space between the contact lens and the corneal surface post TransPRK is prone to a “pseudo-interface pathology” that could mimic diffuse lamellar keratitis-like pathology. Suboptimal lid hygiene, resulting in tear film combinations of bacteria, inflammatory cells, matrix metalloproteinases and other proteolytic enzymes, contributes to the degradation of vulnerable, exposed collagen stromal tissue post TransPRK or any surface corneal ablation. Refractive surgeons should maintain a healthy lid margin and tear

  18. Persistent Epithelial Defects and Corneal Opacity After Collagen Cross-Linking With Substitution of Dextran (T-500) With Dextran Sulfate in Compounded Topical Riboflavin.

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    Höllhumer, Roland; Watson, Stephanie; Beckingsale, Peter

    2017-03-01

    Collagen cross-linking (CXL) is a commonly performed procedure to prevent the progression of keratoconus. Riboflavin is an essential part of the procedure, which facilitates both the cross-linking process and protection of intraocular structures. Dextran can be added to riboflavin to create an isotonic solution. This case report highlights the importance of compounding riboflavin with the correct dextran solution. A retrospective case series. Six eyes of 4 male patients with keratoconus aged from 20 to 38 years underwent CXL with substitution of 20% dextran (T-500) with 20% dextran sulfate in a compounded riboflavin 0.1% solution. Postoperatively, persistent corneal epithelial defects, stromal haze, and then scarring occurred. Corneal transplantation was performed for visual rehabilitation but was complicated by graft rejection followed by failure (n = 1 eye), dehiscence (n = 4), cataract (n = 2), post-laser ablation haze (n = 1), and steroid-induced glaucoma (n = 2). The visual outcome was dextran (T-500) with dextran sulfate in riboflavin solutions during CXL results in loss of vision from permanent corneal opacity. Residual host changes may compromise the results of corneal transplantation.

  19. Corneal collagen cross-linking for progressive keratoconus in patients aged 9 to 14

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    Fernando Plazzi Palis

    2016-04-01

    Full Text Available RESUMO Objetivo: Determinar a segurança e eficácia do cross-linking corneano (CXL em pacientes de 9 a 14 anos de idade com ceratocone progressivo. Métodos: Dezesseis olhos de onze pacientes (8 homens e 3 mulheres com ceratocone progressivo foram submetidos ao CXL, de acordo com o protocolo padrão de Dresden. A média do tempo de seguimento foi de 26 meses (variando de 12 a 60 meses. Os exames pré e pós-operatórios incluíram: acuidade visual sem correção (AVSC, melhor acuidade visual com correção (AVCC, topografia corneana, tonometria, refração, paquimetria corneana, e contagem de células endoteliais. Resultados: Na última visita de acompanhamento ambulatorial, a AVCC melhorou pelo menos uma linha na tabela de Snellen em 6 olhos (37,5% e permaneceu estável em 9 olhos (56,25%. Dois olhos (12,5% de pacientes que coçam os olhos com frequência, exigiram retratamento devido à progressão do ceratocone, 15 e 28 meses após o primeiro CXL. A refração e contagem de células endoteliais mantiveram-se estáveis. Os resultados topográficos mostraram melhora estatisticamente significativa nos valores do K máximo até dois anos após o CXL. No entanto, houve perda de significância ao longo do tempo. Nenhuma complicação peroperatória foi observada. Dois olhos (12,5% apresentaram haze grau I, que regrediu após um mês de terapia com esteróide tópico. Conclusão: Neste estudo com pacientes selecionados, de 9 a 14 anos de idade, o CXL mostrou ser uma opção segura e eficaz para o tratamento do ceratocone progressivo. No entanto, o efeito pode não ser duradouro, podendo ser necessário um novo tratamento. Maior amostragem e maior seguimento são necessários para verificar esta tendência.

  20. Corneal collagen crosslinking for keratoconus. A review

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    M. M. Bikbov

    2014-10-01

    Full Text Available Photochemical crosslinking is widely applied in ophthalmology. Its biochemical effect is due to the release of singlet oxygen that promotes anaerobic photochemical reaction. Keratoconus is one of the most common corneal ectasia affecting 1 in 250 to 250 000 persons. Currently, the rate of iatrogenic ectasia following eximer laser refractive surgery increases due to biomechanical weakening of the cornea. Morphologically and biochemically, ectasia is characterized by corneal layers thinning, contact between the stroma and epithelium resulting from Bowman’s membrane rupture, chromatin fragmentation in keratocyte nuclei, phagocytosis, abnormal staining and arrangement of collagen fibers, enzyme system disorders, and keratocyte apoptosis. In corneal ectasia, altered enzymatic processes result in the synthesis of abnormal collagen. Collagen packing is determined by the activity of various extracellular matrix enzymes which bind amines and aldehydes of collagen fiber amino acids. In the late stage, morphological changes of Descemet’s membrane (i.e., rupture and detachment develop. Abnormal hexagonal-shaped keratocytes and their apoptosis are the signs of endothelial dystrophy. The lack of analogs in domestic ophthalmology encouraged the scientists of Ufa Eye Research Institute to develop a device for corneal collagen crosslinking. The parameters of ultraviolet (i.e., wavelength, exposure time, power to achieve the desired effect were identified. The specifics of some photosensitizers in the course of the procedure were studied. UFalink, a device for UV irradiation of cornea, and photosensitizer Dextralink were developed and adopted. Due to the high risk of endothelial damage, this treatment is contraindicated in severe keratoconus (CCT less than 400 microns. Major effects of corneal collagen crosslinking are the following: Young’s modulus (modulus of elasticity increase by 328.9 % (on average, temperature tolerance increase by 5

  1. 5-year follow-up of combined non-topography guided photorefractive keratectomy and corneal collagen cross linking for keratoconus

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    Abdulrahman Mohammed Al-Amri

    2018-01-01

    Full Text Available AIM: To evaluate the visual outcomes of simultaneous non-topography guided photorefractive keratectomy (PRK and corneal collagen cross-linking (CXL in eyes with keratoconus 5y after the procedure. METHODS: Prospective, interventional, non-randomized, and non-controlled case series design was used. Sixty eyes of 30 patients (16 males and 14 females; age: 21-41y with mild, non-progressive (stages 1-2 keratoconus were enrolled. Refraction, uncorrected distance visual acuity (UDVA and corrected distance visual acuity (CDVA , flat and steep keratometry readings, and adverse events were evaluated preoperatively and postoperatively. Data were collected preoperatively and postoperatively at 3mo, 1, 2, 3, 4, and 5y follow-up visits after combined non-topography-guided PRK with CXL was performed. All patients had at least 5y of follow-up. RESULTS: All study parameters showed a statistically significant improvement at 5y over baseline values. The mean follow-up time was 68.20±4.71mo (range: 60-106mo. Patients showed a significant improvement in UDVA from 1.24±0.79 logMAR prior to combined non-TG-PRK+CXL to 0.06±0.15 logMAR postoperatively at the time of their last follow-up visit. CDVA significantly increased from 0.06±0.19 logMAR preoperatively to 0.03±0.12 logMAR postoperatively. A significant decrease in the mean spherical equivalent (SE refraction was observed from -2.28±1.8 to -0.79±0.93 diopters (D (P<0.05, and the manifest sphere decreased from -1.62±1.23 to -0.27±0.21 D (P=0.001. The manifest cylinder significantly decreased from -1.73±0.86 to -0.29±0.34 D postoperatively (P=0.001. The mean steep keratometry was 45.13±1.32 vs 47.28±2.12 D preoperatively (P<0.05, and the preoperative mean steepest keratometry (Kmax 48.6±3.1 was reduced significantly to 46.8±2.9 postoperatively (P<0.05. CONCLUSION: Combined non-TG-PRK with 15min CXL is an effective and safe option for correcting mild refractive error and improving visual acuity in

  2. Safety and efficacy of simultaneous corneal collagen cross-linking with topography-guided PRK in managing low-grade keratoconus: 1-year follow-up.

    Science.gov (United States)

    Tuwairqi, Waleed S; Sinjab, Mazen M

    2012-05-01

    To evaluate 1-year visual and topographic outcomes and safety and efficacy of corneal collagen cross-linking (CXL) combined with topography-guided photorefractive keratectomy (TG-PRK) to achieve near emmetropia in eyes with low-grade keratoconus. Twenty-two eyes from 15 patients (11 women, 4 men) were included in a prospective, nonrandomized, noncontrolled clinical study. Mean patient age was 26.6±6.07 years (range: 19 to 40 years). Inclusion criteria were low-grade keratoconus with evidence of progression, transparent cornea, corrected distance visual acuity (CDVA) 0.8 (decimal) or better, corneal thickness >440 μm, and maximum keratometry readings (K-max) PRK with CXL. Study parameters were uncorrected distance visual acuity, CDVA, manifest refractive error, manifest and topographic (corneal) astigmatism, patient satisfaction, and efficacy and safety of the treatment. Follow-up was 1 year. After 1 year, statistically significant improvement was noted in all study parameters (PPRK with CXL is an effective and safe treatment with remarkable visual and topographic outcomes in patients with low-grade keratoconus who meet the recommended inclusion criteria. Copyright 2012, SLACK Incorporated.

  3. Collagen cross linking: Current perspectives

    Directory of Open Access Journals (Sweden)

    Srinivas K Rao

    2013-01-01

    Full Text Available Keratoconus is a common ectatic disorder occurring in more than 1 in 1,000 individuals. The condition typically starts in adolescence and early adulthood. It is a disease with an uncertain cause and its progression is unpredictable, but in extreme cases, vision deteriorates and can require corneal transplant surgery. Corneal collagen cross-linking (CCL with riboflavin (C3R is a recent treatment option that can enhance the rigidity of the cornea and prevent disease progression. Since its inception, the procedure has evolved with newer instrumentation, surgical techniques, and is also now performed for expanded indications other than keratoconus. With increasing experience, newer guidelines regarding optimization of patient selection, the spectrum of complications and their management, and combination procedures are being described. This article in conjunction with the others in this issue, will try and explore the uses of collagen cross-linking (CXL in its current form.

  4. Corneal Collagen Cross-Linking Combined with an Artiflex Iris-Fixated Anterior Chamber Phakic Intraocular Lens Implantation in a Patient with Progressive Keratoconus

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    Sharif Hashmani

    2017-10-01

    Full Text Available We present here the case of a 24-year-old male who experienced progressive keratoconus and vision loss which adversely affected his ability to carry out everyday tasks. This landed him in the Hashmanis Hospital for consultation. He had a preoperative best corrected visual acuity of 6/12. He underwent multiple Oculus Pentacam examinations, which showed progressive keratoconus. Corneal collagen cross-linking (CXL was performed to stabilize his cornea and, subsequently, an Artiflex anterior chamber iris-fixated phakic intraocular lens (ACIF-PIOL was implanted to alleviate his refractive errors. The patient achieved a postoperative uncorrected visual acuity of 6/12. This report shows that CXL combined with ACIF-PIOL can be safe and effective in those with progressive keratoconus.

  5. Safety and Efficacy of Epithelium-On Corneal Collagen Cross-Linking Using a Multifactorial Approach to Achieve Proper Stromal Riboflavin Saturation

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    Aleksandar Stojanovic

    2012-01-01

    Full Text Available Purpose. To evaluate the efficacy and safety of epithelium-on corneal collagen cross-linking (CXL using a multifactorial approach to achieve proper stromal riboflavin saturation. Methods. This non-randomized retrospective study comprised 61 eyes with progressive keratoconus treated with epithelium-on CXL. Chemical epithelial penetration enhancement (benzalkonium chloride-containing local medication and hypotonic riboflavin solution, mechanical disruption of the superficial epithelium, and prolongation of the riboflavin-induction time until verification of stromal saturation were used before the UVA irradiation. Uncorrected and corrected distance visual acuity (UDVA, CDVA, refraction, corneal topography, and aberrometry were evaluated at baseline and at 1, 3, 6, and 12 months postoperative. Results. At 12-month, UDVA and CDVA improved significantly. None of the eyes lost lines of CDVA, while 27.4% of the eyes gained 2 or more lines. Mean spherical equivalent decreased by 0.74 D, and mean cylindrical reduction was 1.15 D. Irregularity index and asymmetry from Scheimpflug-based topography and Max-K at the location of cone from Placido-based topography showed a significant decrease. Higher-order-aberration data demonstrated a slight reduction in odd-order aberrations S 3, 5,7 (=0.04. Postoperative pain without other complications was recorded. Conclusion. Epithelium-on CXL with our novel protocol appeared to be safe and effective in the treatment of progressive keratoconus.

  6. Influence of corneal collagen crosslinking with riboflavin and ultraviolet-a irradiation on excimer laser surgery.

    NARCIS (Netherlands)

    Kampik, D.; Ralla, B.; Keller, S.; Hirschberg, M.; Friedl, P.H.A.; Geerling, G.

    2010-01-01

    PURPOSE: Riboflavin/ultraviolet A (UVA) cross-linking (CXL) of corneal collagen is a novel method of stabilizing corneal mechanical properties and preventing progression of keratectasias. This study was conducted to investigate whether CXL influences ablation rate, flap thickness, and refractive

  7. The Effect of Riboflavin/UVA Collagen Cross-linking Therapy on the Structure and Hydrodynamic Behaviour of the Ungulate and Rabbit Corneal Stroma

    Science.gov (United States)

    Hayes, Sally; Kamma-Lorger, Christina S.; Boote, Craig; Young, Robert D.; Quantock, Andrew J.; Rost, Anika; Khatib, Yasmeen; Harris, Jonathan; Yagi, Naoto; Terrill, Nicholas; Meek, Keith M.

    2013-01-01

    Purpose To examine the effect of riboflavin/UVA corneal crosslinking on stromal ultrastructure and hydrodynamic behaviour. Methods One hundred and seventeen enucleated ungulate eyes (112 pig and 5 sheep) and 3 pairs of rabbit eyes, with corneal epithelium removed, were divided into four treatment groups: Group 1 (28 pig, 2 sheep and 3 rabbits) were untreated; Group 2 (24 pig) were exposed to UVA light (3.04 mW/cm2) for 30 minutes and Group 3 (29 pig) and Group 4 (31 pig, 3 sheep and 3 rabbits) had riboflavin eye drops applied to the corneal surface every 5 minutes for 35 minutes. Five minutes after the initial riboflavin instillation, the corneas in Group 4 experienced a 30 minute exposure to UVA light (3.04 mW/cm2). X-ray scattering was used to obtain measurements of collagen interfibrillar spacing, spatial order, fibril diameter, D-periodicity and intermolecular spacing throughout the whole tissue thickness and as a function of tissue depth in the treated and untreated corneas. The effect of each treatment on the hydrodynamic behaviour of the cornea (its ability to swell in saline solution) and its resistance to enzymatic digestion were assessed using in vitro laboratory techniques. Results Corneal thickness decreased significantly following riboflavin application (priboflavin/UVA therapy occur predominantly at the collagen fibril surface and in the protein network surrounding the collagen. PMID:23349690

  8. Corneal Collagen Cross-Linking in the Management of Keratoconus in Canada: A Cost-Effectiveness Analysis.

    Science.gov (United States)

    Leung, Victoria C; Pechlivanoglou, Petros; Chew, Hall F; Hatch, Wendy

    2017-08-01

    To use patient-level microsimulation models to evaluate the comparative cost-effectiveness of early corneal cross-linking (CXL) and conventional management with penetrating keratoplasty (PKP) when indicated in managing keratoconus in Canada. Cost-utility analysis using individual-based, state-transition microsimulation models. Simulated cohorts of 100 000 individuals with keratoconus who entered each treatment arm at 25 years of age. Fellow eyes were modeled separately. Simulated individuals lived up to a maximum of 110 years. We developed 2 state-transition microsimulation models to reflect the natural history of keratoconus progression and the impact of conventional management with PKP versus CXL. We collected data from the published literature to inform model parameters. We used realistic parameters that maximized the potential costs and complications of CXL, while minimizing those associated with PKP. In each treatment arm, we allowed simulated individuals to move through health states in monthly cycles from diagnosis until death. For each treatment strategy, we calculated the total cost and number of quality-adjusted life years (QALYs) gained. Costs were measured in Canadian dollars. Costs and QALYs were discounted at 5%, converting future costs and QALYs into present values. We used an incremental cost-effectiveness ratio (ICER = difference in lifetime costs/difference in lifetime health outcomes) to compare the cost-effectiveness of CXL versus conventional management with PKP. Lifetime costs and QALYs for CXL were estimated to be Can$5530 (Can$4512, discounted) and 50.12 QALYs (16.42 QALYs, discounted). Lifetime costs and QALYs for conventional management with PKP were Can$2675 (Can$1508, discounted) and 48.93 QALYs (16.09 QALYs, discounted). The discounted ICER comparing CXL to conventional management was Can$9090/QALY gained. Sensitivity analyses revealed that in general, parameter variations did not influence the cost-effectiveness of CXL. CXL is

  9. Riboflavin for corneal cross-linking.

    Science.gov (United States)

    O'Brart, D P S

    2016-06-01

    Corneal collagen cross-linking (CXL) with riboflavin and ultraviolet A (UVA) radiation is the first therapeutic modality that appears to arrest the progression of keratoconus and other corneal ectasias. Riboflavin is central to the process, acting as a photosensitizer for the production of oxygen singlets and riboflavin triplets. These free radicals drive the CXL process within the proteins of the corneal stroma, altering its biomechanical properties. Riboflavin also absorbs the majority of the UVA radiation, which is potentially cytotoxic and mutagenic, within the anterior stroma, preventing damage to internal ocular structures, such as the corneal endothelium, lens and retina. Clinical studies report cessation of ectatic progression in over 90% of cases and the majority document significant improvements in visual, keratometric and topographic parameters. Clinical follow-up is limited to 5-10 years, but suggests sustained stability and enhancement in corneal shape. Sight-threatening complications are rare. The optimal stromal riboflavin dosage for CXL is as yet undetermined. Copyright 2016 Prous Science, S.A.U. or its licensors. All rights reserved.

  10. Improving the mechanical properties of collagen-based membranes using silk fibroin for corneal tissue engineering.

    Science.gov (United States)

    Long, Kai; Liu, Yang; Li, Weichang; Wang, Lin; Liu, Sa; Wang, Yingjun; Wang, Zhichong; Ren, Li

    2015-03-01

    Although collagen with outstanding biocompatibility has promising application in corneal tissue engineering, the mechanical properties of collagen-based scaffolds, especially suture retention strength, must be further improved to satisfy the requirements of clinical applications. This article describes a toughness reinforced collagen-based membrane using silk fibroin. The collagen-silk fibroin membranes based on collagen [silk fibroin (w/w) ratios of 100:5, 100:10, and 100:20] were prepared by using silk fibroin and cross-linking by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. These membranes were analyzed by scanning electron microscopy and their optical property, and NaCl and tryptophan diffusivity had been tested. The water content was found to be dependent on the content of silk fibroin, and CS10 membrane (loading 10 wt % of silk fibroin) performed the optimal mechanical properties. Also the suture experiments have proved CS10 has high suture retention strength, which can be sutured in rabbit eyes integrally. Moreover, the composite membrane proved good biocompatibility for the proliferation of human corneal epithelial cells in vitro. Lamellar keratoplasty shows that CS10 membrane promoted complete epithelialization in 35 ± 5 days, and their transparency is restored quickly in the first month. Corneal rejection reaction, neovascularization, and keratoconus are not observed. The composite films show potential for use in the field of corneal tissue engineering. © 2014 Wiley Periodicals, Inc.

  11. Simultaneous versus Sequential Accelerated Corneal Collagen Cross-Linking and Wave Front Guided PRK for Treatment of Keratoconus: Objective and Subjective Evaluation.

    Science.gov (United States)

    Abou Samra, Waleed Ali; El Emam, Dalia Sabry; Farag, Rania Kamel; Abouelkheir, Hossam Youssef

    2016-01-01

    Aim . To compare objective and subjective outcome after simultaneous wave front guided (WFG) PRK and accelerated corneal cross-linking (CXL) in patients with progressive keratoconus versus sequential WFG PRK 6 months after CXL. Methods . 62 eyes with progressive keratoconus were divided into two groups; the first including 30 eyes underwent simultaneous WFG PRK with accelerated CXL. The second including 32 eyes underwent subsequent WFG PRK performed 6 months later after accelerated CXL. Visual, refractive, topographic, and aberrometric data were determined preoperatively and during 1-year follow-up period and the results compared in between the 2 studied groups. Results . All evaluated visual, refractive, and aberrometric parameters demonstrated highly significant improvement in both studied groups (all P PRK and accelerated CXL is an effective and safe option to improve the vision in mild to moderate keratoconus. In one-year follow-up, there is no statistically significant difference between the simultaneous and sequential procedure.

  12. Collagen cross-linking in thin corneas

    Directory of Open Access Journals (Sweden)

    Prema Padmanabhan

    2013-01-01

    Full Text Available Collagen cross-linking (CXL has become the standard of care for progressive keratoconus, after numerous clinical studies have established its efficacy and safety in suitably selected eyes. The standard protocol is applicable in eyes which have a minimum corneal thickness of 400 μm after epithelial debridement. This prerequisite was stipulated to protect the corneal endothelium and intraocular tissues from the deleterious effect of ultraviolet-A (UVA radiation. However, patients with keratoconus often present with corneal thickness of less than 400 μm and could have otherwise benefited from this procedure. A few modifications of the standard procedure have been suggested to benefit these patients without a compromise in safety. Transepithelial cross-linking, pachymetry-guided epithelial debridement before cross-linking, and the use of hypoosmolar riboflavin are some of the techniques that have been attempted. Although clinical data is limited at the present time, these techniques are worth considering in patients with thin corneas. Further studies are needed to scientifically establish their efficacy and safety.

  13. [Biophysical principles of collagen cross-linking].

    Science.gov (United States)

    Spörl, E; Raiskup-Wolf, F; Pillunat, L E

    2008-02-01

    The reduced mechanical stability of the cornea in keratoconus or in keratectasia after Lasik may be increased by photooxidative cross-linking of corneal collagen. The biophysical principles are compiled for the safe and effective application of this new treatment method. The setting of the therapy parameters should be elucidated from the absorption behaviour of the cornea. The safety of the method for the endothelium cells and the lens will be discussed. The induced cross-links are shown to be the result of changes in the physico-chemical properties of the cornea. To reach a high absorption of the irradiation energy in the cornea, riboflavin of a concentration of 0.1% and UV light of a wavelength of 370 nm, corresponding to the relative maximum of absorption of riboflavin, were used. An irradiance of 3 mW/cm(2) and an irradiation time of 30 min lead to an increase of the mechanical stiffness. The endothelium cells will be protected due to the high absorption within the cornea, that means the damaging threshold of the endothelium cells will not be reached in a 400 microm thick stroma. As evidence for cross-links we can consider the increase of the biomechanical stiffness, the increased resistance against enzymatic degradation, a higher shrinkage temperature, a lower swelling rate and an increased diameter of collagen fibres. The therapy parameters were tested experimentally and have been proven clinically in the corneal collagen cross-linking. These parameters should be respected to reach a safe cross-linking effect without damage of the adjacent tissues.

  14. Simultaneous versus Sequential Accelerated Corneal Collagen Cross-Linking and Wave Front Guided PRK for Treatment of Keratoconus: Objective and Subjective Evaluation

    Directory of Open Access Journals (Sweden)

    Waleed Ali Abou Samra

    2016-01-01

    Full Text Available Aim. To compare objective and subjective outcome after simultaneous wave front guided (WFG PRK and accelerated corneal cross-linking (CXL in patients with progressive keratoconus versus sequential WFG PRK 6 months after CXL. Methods. 62 eyes with progressive keratoconus were divided into two groups; the first including 30 eyes underwent simultaneous WFG PRK with accelerated CXL. The second including 32 eyes underwent subsequent WFG PRK performed 6 months later after accelerated CXL. Visual, refractive, topographic, and aberrometric data were determined preoperatively and during 1-year follow-up period and the results compared in between the 2 studied groups. Results. All evaluated visual, refractive, and aberrometric parameters demonstrated highly significant improvement in both studied groups (all P<0.001. A significant improvement was observed in keratometric and Q values. The improvement in all parameters was stable till the end of follow-up. Likewise, no significant difference was determined in between the 2 groups in any of recorded parameters. Subjective data revealed similarly significant improvement in both groups. Conclusions. WFG PRK and accelerated CXL is an effective and safe option to improve the vision in mild to moderate keratoconus. In one-year follow-up, there is no statistically significant difference between the simultaneous and sequential procedure.

  15. The management of cornea blindness from severe corneal scarring, with the Athens Protocol (transepithelial topography-guided PRK therapeutic remodeling, combined with same-day, collagen cross-linking

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2012-02-01

    Full Text Available Anastasios John KanellopoulosLaservision.gr Institute, Athens, Greece; Manhattan Eye, Ear and Throat Hospital, New York, NY, USA; New York University Medical School, New York, NY, USAPurpose: To evaluate the safety and efficacy of combined transepithelial topography-guided photorefractive keratectomy (PRK therapeutic remodeling, combined with same-day, collagen cross-linking (CXL. This protocol was used for the management of cornea blindness due to severe corneal scarring.Methods: A 57-year-old man had severe corneal blindness in both eyes. Both corneas had significant central scars attributed to a firework explosion 45 years ago, when the patient was 12 years old. Corrected distance visual acuity (CDVA was 20/100 both eyes (OU with refraction: +4.00, –4.50 at 135° in the right eye and +3.50, –1.00 at 55° in the left. Respective keratometries were: 42.3, 60.4 at 17° and 35.8, 39.1 at 151.3°. Cornea transplantation was the recommendation by multiple cornea specialists as the treatment of choice. We decided prior to considering a transplant to employ the Athens Protocol (combined topography-guided partial PRK and CXL in the right eye in February 2010 and in the left eye in September 2010. The treatment plan for both eyes was designed on the topography-guided wavelight excimer laser platform.Results: Fifteen months after the right eye treatment, the right cornea had improved translucency and was topographically stable with uncorrected distance visual acuity (UDVA 20/50 and CDVA 20/40 with refraction +0.50, –2.00 at 5°. We noted a similar outcome after similar treatment applied in the left eye with UDVA 20/50 and CDVA 20/40 with –0.50, –2.00 at 170° at the 8-month follow-up.Conclusion: In this case, the introduction of successful management of severe cornea abnormalities and scarring with the Athens Protocol may provide an effective alternative to other existing surgical or medical options.Keywords: Athens Protocol, collagen cross

  16. The management of cornea blindness from severe corneal scarring, with the Athens Protocol (transepithelial topography-guided PRK therapeutic remodeling, combined with same-day, collagen cross-linking).

    Science.gov (United States)

    Kanellopoulos, Anastasios John

    2012-01-01

    To evaluate the safety and efficacy of combined transepithelial topography-guided photorefractive keratectomy (PRK) therapeutic remodeling, combined with same-day, collagen cross-linking (CXL). This protocol was used for the management of cornea blindness due to severe corneal scarring. A 57-year-old man had severe corneal blindness in both eyes. Both corneas had significant central scars attributed to a firework explosion 45 years ago, when the patient was 12 years old. Corrected distance visual acuity (CDVA) was 20/100 both eyes (OU) with refraction: +4.00, -4.50 at 135° in the right eye and +3.50, -1.00 at 55° in the left. Respective keratometries were: 42.3, 60.4 at 17° and 35.8, 39.1 at 151.3°. Cornea transplantation was the recommendation by multiple cornea specialists as the treatment of choice. We decided prior to considering a transplant to employ the Athens Protocol (combined topography-guided partial PRK and CXL) in the right eye in February 2010 and in the left eye in September 2010. The treatment plan for both eyes was designed on the topography-guided wavelight excimer laser platform. Fifteen months after the right eye treatment, the right cornea had improved translucency and was topographically stable with uncorrected distance visual acuity (UDVA) 20/50 and CDVA 20/40 with refraction +0.50, -2.00 at 5°. We noted a similar outcome after similar treatment applied in the left eye with UDVA 20/50 and CDVA 20/40 with -0.50, -2.00 at 170° at the 8-month follow-up. In this case, the introduction of successful management of severe cornea abnormalities and scarring with the Athens Protocol may provide an effective alternative to other existing surgical or medical options.

  17. Optical coherence elastography for evaluating customized riboflavin/UV-A corneal collagen crosslinking

    Science.gov (United States)

    Singh, Manmohan; Li, Jiasong; Vantipalli, Srilatha; Han, Zhaolong; Larin, Kirill V.; Twa, Michael D.

    2017-09-01

    UV-induced collagen cross-linking is a promising treatment for keratoconus that stiffens corneal tissue and prevents further degeneration. Since keratoconus is generally localized, the efficacy of collagen cross-linking (CXL) treatments could be improved by stiffening only the weakened parts of the cornea. Here, we demonstrate that optical coherence elastography (OCE) can spatially resolve transverse variations in corneal stiffness. A short duration (≤1 ms) focused air-pulse induced low amplitude (≤10 μm) deformations in the samples that were detected using a phase-stabilized optical coherence tomography system. A two-dimensional map of material stiffness was generated by measuring the damped natural frequency (DNF) of the air-pulse induced response at various transverse locations of a heterogeneous phantom mimicking a customized CXL treatment. After validation on the phantoms, similar OCE measurements were made on spatially selective CXL-treated in situ rabbit corneas. The results showed that this technique was able to clearly distinguish the untreated and CXL-treated regions of the cornea, where CXL increased the DNF of the cornea by ˜51%. Due to the noncontact nature and minimal excitation force, this technique may be valuable for in vivo assessments of corneal biomechanical properties.

  18. Evaluation of Biomechanical Changes in Myopia Patients with Unsatisfactory Corneas After Femto Second-Laser In Situ Keratomileusis (FS-LASIK) Concurrent with Accelerated Corneal Collagen Cross-Linking Using Corvis-ST: Two-Year Follow-Up Results.

    Science.gov (United States)

    Xu, Weiwei; Tao, Ye; Wang, Liqiang; Huang, Yifei

    2017-07-27

    BACKGROUND Some myopia patients with unsatisfactory corneas consider corneal refractive surgery for different reasons. Accelerated corneal collagen crosslinking (ACXL) is an effective method to enhance the resistance of the cornea. The present investigation was designed to evaluate the changes of biomechanical properties in patients with myopia and thin corneas after femtosecond-laser in situ keratomileusis (FS-LASIK) concurrent with ACXL. MATERIAL AND METHODS A prospective study was designed. A total of 22 eyes of 11 myopia astigmatism patients with unsatisfactory corneas were enrolled. The patients were assigned to femtosecond-laser in situ keratomileusis concurrent with accelerated corneal collagen crosslinking (FS-LASIK-ACXL). The follow-up duration was 24 months. Manifest refraction, uncorrected (UDVA), and corrected distance visual acuity (CDVA), ultra-high-speed camera (Corvis-ST), corneal topography, anterior segment OCT (AS-OCT), Pentacam, and endothelial cell density (ECD) were examined before and after the operation. The corneal biomechanical and refractive data was analyzed using SAS9.3. Data were analyzed through normal distribution test and variance of analysis. The difference was considered as statistically significant when pLASIK-ACXL operation. The values of first applanation length (A1L), the second applanation length (A2L), the first applanation velocity (A1V), the second applanation velocity (A2V), deformation amplitude (DA), highest concavity peak distance (PD), and radius of curvature at the time of highest concavity (HCR) did not show significant difference after the operation. CONCLUSIONS FS-LASIK-ACXL is an effective and safe surgery for improving visual acuity for myopic patients with thin corneas, and it does not increase the risk of iatrogenic keratectasia.

  19. The structural and optical properties of type III human collagen biosynthetic corneal substitutes

    Science.gov (United States)

    Hayes, Sally; Lewis, Phillip; Islam, M. Mirazul; Doutch, James; Sorensen, Thomas; White, Tomas; Griffith, May; Meek, Keith M.

    2015-01-01

    The structural and optical properties of clinically biocompatible, cell-free hydrogels comprised of synthetically cross-linked and moulded recombinant human collagen type III (RHCIII) with and without the incorporation of 2-methacryloyloxyethyl phosphorylcholine (MPC) were assessed using transmission electron microscopy (TEM), X-ray scattering, spectroscopy and refractometry. These findings were examined alongside similarly obtained data from 21 human donor corneas. TEM demonstrated the presence of loosely bundled aggregates of fine collagen filaments within both RHCIII and RHCIII-MPC implants, which X-ray scattering showed to lack D-banding and be preferentially aligned in a uniaxial orientation throughout. This arrangement differs from the predominantly biaxial alignment of collagen fibrils that exists in the human cornea. By virtue of their high water content (90%), very fine collagen filaments (2–9 nm) and lack of cells, the collagen hydrogels were found to transmit almost all incident light in the visible spectrum. They also transmitted a large proportion of UV light compared to the cornea which acts as an effective UV filter. Patients implanted with these hydrogels should be cautious about UV exposure prior to regrowth of the epithelium and in-growth of corneal cells into the implants. PMID:26159106

  20. Thermal and infrared-diode laser effects on indocyanine-green-treated corneal collagen

    Science.gov (United States)

    Timberlake, George T.; Patmore, Ann; Shallal, Assaad; McHugh, Dominic; Marshall, John

    1993-07-01

    It has been suggested that laser welds of collagenous tissues form by interdigitation and chemical bonding of thermally 'unraveled' collagen fibrils. We investigated this proposal by attempting to weld highly collagenous, avascular corneal tissue with an infrared (IR) diode laser as follows. First, the temperature at which corneal collagen shrinks and collagen fibrils 'split' into subfibrillary components was determined. Second, since use of a near-IR laser wavelength necessitated addition of an absorbing dye (indocyanine green (ICG) to the cornea, we measured absorption spectra of ICG-treated tissue to ensure that peak ICG absorbance did not change markedly when ICG was present in the cornea. Third, using gel electrophoresis of thermally altered corneal collagen, we searched for covalently crosslinked compounds predicted by the proposed welding mechanism. Finally, we attempted to weld partial thickness corneal incisions infused with ICG. Principal experimental findings were as follows: (1) Human corneal (type I) collagen splits into subfibrillary components at approximately 63 degree(s)C, the same temperature that produces collagen shrinkage. (2) Peak ICG absorption does not change significantly in corneal stroma or with laser heating. (3) No evidence was found for the formation of novel compounds or the loss of proteins as a result of tissue heating. All tissue treated with ICG, however, exhibited a novel 244 kD protein band indicating chemical activity between collagen and corneal stromal components. (4) Laser welding corneal incisions was unsuccessful possibly due to shrinkage of the sides of the incision, lack of incision compression during heating, or a less than optimal combination of ICG concentration and radiant exposure. In summary, these experiments demonstrate the biochemical and morphological complexity of ICG-enhanced IR laser-tissue welding and the need for further investigation of laser welding mechanisms.

  1. Investigation on fibrous collagen modifications during corneal laser welding by second harmonic generation microscopy

    Science.gov (United States)

    Matteini, Paolo; Ratto, Fulvio; Rossi, Francesca; Cicchi, Riccardo; Stringari, Chiara; Kapsokalyvas, Dimitrios; Pavone, Francesco S.; Pini, Roberto

    2009-02-01

    The structural modifications in the collagen lattice of corneal stroma induced by near-infrared laser welding were investigated with second-harmonic generation (SHG) imaging. The corneal laser welding procedure is performed by staining the wound edges with a saturated water solution of Indocyanine Green (ICG) followed by irradiation with a 810 nm diode laser operated in continuous (CWLW: continuous wave laser welding) or pulsed (PLW: pulsed laser welding) mode. Both these procedures can provide closure of corneal wounds by inducing different structural modifications in the extracellular matrix. SHG imaging of native corneal stroma revealed collagen bundles composed of many regularly aligned collagen fibrils. After CWLW the regular lamellar arrangement was lost; collagen bundles appeared densely packed with an increasing disordered arrangement toward the welded cut. The weld was characterized by a loss of details; nevertheless, the observation of the second harmonic signal at this site indicated the lack of collagen denaturation. By contrast, PLW mode produced welding spots at the interface between donor and recipient corneal layers, which were characterized by a severe loss of the SHG signal, suggesting the occurrence of a complete collagen denaturation. SHG imaging appeared to be a powerful tool for visualizing the supramolecular morphological modifications in the collagen matrix after laser welding.

  2. Engineering of Corneal Tissue through an Aligned PVA/Collagen Composite Nanofibrous Electrospun Scaffold.

    Science.gov (United States)

    Wu, Zhengjie; Kong, Bin; Liu, Rui; Sun, Wei; Mi, Shengli

    2018-02-24

    Corneal diseases are the main reason of vision loss globally. Constructing a corneal equivalent which has a similar strength and transparency with the native cornea, seems to be a feasible way to solve the shortage of donated cornea. Electrospun collagen scaffolds are often fabricated and used as a tissue-engineered cornea, but the main drawback of poor mechanical properties make it unable to meet the requirement for surgery suture, which limits its clinical applications to a large extent. Aligned polyvinyl acetate (PVA)/collagen (PVA-COL) scaffolds were electrospun by mixing collagen and PVA to reinforce the mechanical strength of the collagen electrospun scaffold. Human keratocytes (HKs) and human corneal epithelial cells (HCECs) inoculated on aligned and random PVA-COL electrospun scaffolds adhered and proliferated well, and the aligned nanofibers induced orderly HK growth, indicating that the designed PVA-COL composite nanofibrous electrospun scaffold is suitable for application in tissue-engineered cornea.

  3. Current status of accelerated corneal cross-linking

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    Michael Mrochen

    2013-01-01

    Full Text Available Corneal cross-linking with riboflavin is a technique to stabilize or reduce corneal ectasia, in diseases such as keratoconus and post-laser-assisted in situ keratomileusis (LASIK ectasia. There is an interest by patient as well as clinicians to reduce the overall treatment time. Especially, the introduction of corneal cross-linking in combination with corneal laser surgery demands a shorter treatment time to assure a sufficient patient flow. The principles and techniques of accelerated corneal cross-linking is discussed.

  4. Human Bone Derived Collagen for the Development of an Artificial Corneal Endothelial Graft. In Vivo Results in a Rabbit Model.

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    Natalia Vázquez

    Full Text Available Corneal keratoplasty (penetrating or lamellar using cadaveric human tissue, is nowadays the main treatment for corneal endotelial dysfunctions. However, there is a worldwide shortage of donor corneas available for transplantation and about 53% of the world's population have no access to corneal transplantation. Generating a complete cornea by tissue engineering is still a tough goal, but an endothelial lamellar graft might be an easier task. In this study, we developed a tissue engineered corneal endothelium by culturing human corneal endothelial cells on a human purified type I collagen membrane. Human corneal endothelial cells were cultured from corneal rims after corneal penetrating keratoplasty and type I collagen was isolated from remnant cancellous bone chips. Isolated type I collagen was analyzed by western blot, liquid chromatography -mass spectrometry and quantified using the exponentially modified protein abundance index. Later on, collagen solution was casted at room temperature obtaining an optically transparent and mechanically manageable membrane that supports the growth of human and rabbit corneal endothelial cells which expressed characteristic markers of corneal endothelium: zonula ocluddens-1 and Na+/K+ ATPase. To evaluate the therapeutic efficiency of our artificial endothelial grafts, human purified type I collagen membranes cultured with rabbit corneal endothelial cells were transplanted in New Zealand white rabbits that were kept under a minimal immunosuppression regimen. Transplanted corneas maintained transparency for as long as 6 weeks without obvious edema or immune rejection and maintaining the same endothelial markers that in a healthy cornea. In conclusion, it is possible to develop an artificial human corneal endothelial graft using remnant tissues that are not employed in transplant procedures. This artificial endothelial graft can restore the integrality of corneal endothelium in an experimental model of

  5. Plastic compressed collagen as a novel carrier for expanded human corneal endothelial cells for transplantation.

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    Hannah J Levis

    Full Text Available Current treatments for reversible blindness caused by corneal endothelial cell failure involve replacing the failed endothelium with donor tissue using a one donor-one recipient strategy. Due to the increasing pressure of a worldwide donor cornea shortage there has been considerable interest in developing alternative strategies to treat endothelial disorders using expanded cell replacement therapy. Protocols have been developed which allow successful expansion of endothelial cells in vitro but this approach requires a supporting material that would allow easy transfer of cells to the recipient. We describe the first use of plastic compressed collagen as a highly effective, novel carrier for human corneal endothelial cells. A human corneal endothelial cell line and primary human corneal endothelial cells retained their characteristic cobblestone morphology and expression of tight junction protein ZO-1 and pump protein Na+/K+ ATPase α1 after culture on collagen constructs for up to 14 days. Additionally, ultrastructural analysis suggested a well-integrated endothelial layer with tightly opposed cells and apical microvilli. Plastic compressed collagen is a superior biomaterial in terms of its speed and ease of production and its ability to be manipulated in a clinically relevant manner without breakage. This method provides expanded endothelial cells with a substrate that could be suitable for transplantation allowing one donor cornea to potentially treat multiple patients.

  6. Role of Decorin Core Protein in Collagen Organisation in Congenital Stromal Corneal Dystrophy (CSCD.

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    Christina S Kamma-Lorger

    Full Text Available The role of Decorin in organising the extracellular matrix was examined in normal human corneas and in corneas from patients with Congenital Stromal Corneal Dystrophy (CSCD. In CSCD, corneal clouding occurs due to a truncating mutation (c.967delT in the decorin (DCN gene. Normal human Decorin protein and the truncated one were reconstructed in silico using homology modelling techniques to explore structural changes in the diseased protein. Corneal CSCD specimens were also examined using 3-D electron tomography and Small Angle X-ray diffraction (SAXS, to image the collagen-proteoglycan arrangement and to quantify fibrillar diameters, respectively. Homology modelling showed that truncated Decorin had a different spatial geometry to the normal one, with the truncation removing a major part of the site that interacts with collagen, compromising its ability to bind effectively. Electron tomography showed regions of abnormal stroma, where collagen fibrils came together to form thicker fibrillar structures, showing that Decorin plays a key role in the maintenance of the order in the normal corneal extracellular matrix. Average diameter of individual fibrils throughout the thickness of the cornea however remained normal.

  7. Assessment of UVA-Riboflavin Corneal Cross-Linking Using Small Amplitude Oscillatory Shear Measurements.

    Science.gov (United States)

    Aslanides, Ioannis M; Dessi, Claudia; Georgoudis, Panagiotis; Charalambidis, Georgios; Vlassopoulos, Dimitris; Coutsolelos, Athanassios G; Kymionis, George; Mukherjee, Achyut; Kitsopoulos, Theofanis N

    2016-04-01

    The effect of ultraviolet (UV)-riboflavin cross-linking (CXL) has been measured primarily using the strip extensometry technique. We propose a simple and reliable methodology for the assessment of CXL treatment by using an established rheologic protocol based on small amplitude oscillatory shear (SAOS) measurements. It provides information on the average cross-link density and the elastic modulus of treated cornea samples. Three fresh postmortem porcine corneas were used to study the feasibility of the technique, one serving as control and two receiving corneal collagen cross-linking treatment. Subsequently, five pairs of fresh postmortem porcine corneas received corneal collagen cross-linking treatment with riboflavin and UVA-irradiation (370 nm; irradiance of 3 mW/cm2) for 30 minutes (Dresden protocol); the contralateral porcine corneas were used as control samples. After the treatment, the linear viscoelastic moduli of the corneal samples were measured using SAOS measurements and the average cross-linking densities extracted. For all cases investigated, the dynamic moduli of the cross-linked corneas were higher compared to those of the corresponding control samples. The increase of the elastic modulus of the treated samples was between 122% and 1750%. The difference was statistically significant for all tested samples (P = 0.018, 2-tailed t-test). We report a simple and accurate methodology for quantifying the effects of cross-linking on porcine corneas treated with the Dresden protocol by means of SAOS measurements in the linear regime. The measured dynamic moduli, elastic and viscous modulus, represent the energy storage and energy dissipation, respectively. Hence, they provide a means to assess the changing physical properties of the cross-linked collagen networks after CXL treatment.

  8. Quantification of collagen ultrastructure after penetrating keratoplasty - implications for corneal biomechanics.

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    Craig Boote

    Full Text Available To quantify long-term changes in stromal collagen ultrastructure following penetrating keratoplasty (PK, and evaluate their possible implications for corneal biomechanics.A pair of 16 mm post-mortem corneo-scleral buttons was obtained from a patient receiving bilateral penetrating keratoplasty 12 (left/28 (right years previously. Small-angle x-ray scattering quantified collagen fibril spacing, diameter and spatial order at 0.5 mm or 0.25 mm intervals along linear scans across the graft margin. Corresponding control data was collected from two corneo-scleral buttons with no history of refractive surgery. Wide-angle x-ray scattering quantified collagen fibril orientation at 0.25 mm (horizontal×0.25 mm (vertical intervals across both PK specimens. Quantification of orientation changes in the graft margin were verified by equivalent analysis of data from a 13 year post-operative right PK specimen obtained from a second patient in a previous study, and comparison made with new and published data from normal corneas.Marked changes to normal fibril alignment, in favour of tangentially oriented collagen, were observed around the entire graft margin in all PK specimens. The total number of meridional fibrils in the wound margin was observed to decrease by up to 40%, with the number of tangentially oriented fibrils increasing by up to 46%. As a result, in some locations the number of fibrils aligned parallel to the wound outnumbered those spanning it by up to five times. Localised increases in fibril spacing and diameter, with an accompanying reduction in matrix order, were also evident.Abnormal collagen fibril size and spatial order within the PK graft margin are indicative of incomplete stromal wound remodelling and the long term persistence of fibrotic scar tissue. Lasting changes in collagen fibril orientation in and around PK wounds may alter corneal biomechanics and compromise the integrity of the graft-host interface in the long term.

  9. Quantification of Collagen Ultrastructure after Penetrating Keratoplasty – Implications for Corneal Biomechanics

    Science.gov (United States)

    Gardner, Steven J.; Kamma-Lorger, Christina S.; Hayes, Sally; Nielsen, Kim; Hjortdal, Jesper; Sorensen, Thomas; Terrill, Nicholas J.; Meek, Keith M.

    2013-01-01

    Purpose To quantify long-term changes in stromal collagen ultrastructure following penetrating keratoplasty (PK), and evaluate their possible implications for corneal biomechanics. Methods A pair of 16 mm post-mortem corneo-scleral buttons was obtained from a patient receiving bilateral penetrating keratoplasty 12 (left)/28 (right) years previously. Small-angle x-ray scattering quantified collagen fibril spacing, diameter and spatial order at 0.5 mm or 0.25 mm intervals along linear scans across the graft margin. Corresponding control data was collected from two corneo-scleral buttons with no history of refractive surgery. Wide-angle x-ray scattering quantified collagen fibril orientation at 0.25 mm (horizontal)×0.25 mm (vertical) intervals across both PK specimens. Quantification of orientation changes in the graft margin were verified by equivalent analysis of data from a 13 year post-operative right PK specimen obtained from a second patient in a previous study, and comparison made with new and published data from normal corneas. Results Marked changes to normal fibril alignment, in favour of tangentially oriented collagen, were observed around the entire graft margin in all PK specimens. The total number of meridional fibrils in the wound margin was observed to decrease by up to 40%, with the number of tangentially oriented fibrils increasing by up to 46%. As a result, in some locations the number of fibrils aligned parallel to the wound outnumbered those spanning it by up to five times. Localised increases in fibril spacing and diameter, with an accompanying reduction in matrix order, were also evident. Conclusions Abnormal collagen fibril size and spatial order within the PK graft margin are indicative of incomplete stromal wound remodelling and the long term persistence of fibrotic scar tissue. Lasting changes in collagen fibril orientation in and around PK wounds may alter corneal biomechanics and compromise the integrity of the graft-host interface in the

  10. Ultrastructure Organization of Collagen Fibrils and Proteoglycans of Stingray and Shark Corneal Stroma

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    Saud A. Alanazi

    2015-01-01

    Full Text Available We report here the ultrastructural organization of collagen fibrils (CF and proteoglycans (PGs of the corneal stroma of both the stingray and the shark. Three corneas from three stingrays and three corneas from three sharks were processed for electron microscopy. Tissues were embedded in TAAB 031 resin. The corneal stroma of both the stingray and shark consisted of parallel running lamellae of CFs which were decorated with PGs. In the stingray, the mean area of PGs in the posterior stroma was significantly larger than the PGs of the anterior and middle stroma, whereas, in the shark, the mean area of PGs was similar throughout the stroma. The mean area of PGs of the stingray was significantly larger compared to the PGs, mean area of the shark corneal stroma. The CF diameter of the stingray was significantly smaller compared to the CF diameter in the shark. The ultrastructural features of the corneal stroma of both the stingray and the shark were similar to each other except for the CFs and PGs. The PGs in the stingray and shark might be composed of chondroitin sulfate (CS/dermatan sulfate (DS PGs and these PGs with sutures might contribute to the nonswelling properties of the cornea of the stingray and shark.

  11. Collagen Cross-Linking: Current Status and Future Directions

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    Marine Hovakimyan

    2012-01-01

    Full Text Available Collagen cross-linking (CXL using UVA light and riboflavin (vitamin B2 was introduced as a clinical application to stabilize the cornea by inducing cross-links within and between collagen fibers. CXL has been investigated extensively and has been shown clinically to arrest the progression of keratoconic or post-LASIK ectasia. With its minimal cost, simplicity, and proven positive clinical outcome, CXL can be regarded as a useful approach to reduce the number of penetrating keratoplasties performed. Small case series have also indicated that CXL is beneficial in corneal edema by reducing stromal swelling behavior and in keratitis by inhibiting pathogen growth. Despite these encouraging results, CXL remains a relatively new method that is potentially associated with complications. Aspects such as side effects and recurrence rates have still to be elucidated. In light of the growing interest in CXL, our paper summarizes present knowledge about this promising approach. We have intentionally endeavored to include the more relevant studies from the recent literature to provide an overview of the current status of CXL.

  12. Long-term results of cornea collagen cross-linking with riboflavin for keratoconus

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    Vinay Agrawal

    2013-01-01

    Full Text Available Corneal collagen cross-linking with riboflavin and UVA light (CXL is the only method designed to arrest the progression of keratoconus. Visual improvement generally starts 3 months after treatment. Reduction is coma seen on aberrometry in early postoperative phase is also responsible for the improvement in visual acuity. In the light of currently available data we can thus say that CXL is a safe procedure that is successful in arresting keratoconus.

  13. Iontophoresis Transcorneal Delivery Technique for Transepithelial Corneal Collagen Crosslinking With Riboflavin in a Rabbit Model.

    Science.gov (United States)

    Cassagne, Myriam; Laurent, Camille; Rodrigues, Magda; Galinier, Anne; Spoerl, Eberhard; Galiacy, Stéphane D; Soler, Vincent; Fournié, Pierre; Malecaze, François

    2016-02-01

    We compared an iontophoresis riboflavin delivery technique for transepithelial corneal collagen crosslinking (I-CXL) with a conventional CXL (C-CXL). We designed three experimental sets using 152 New Zealand rabbits to study riboflavin application by iontophoresis using charged riboflavin solution (Ricrolin+) with a 1-mA current for 5 minutes. The first set was to compare riboflavin concentration measured by HPLC in corneas after iontophoresis or conventional riboflavin application. The second set was to analyze autofluorescence and stromal collagen modification immediately and 14 days after I-CXL or C-CXL, by using nonlinear two-photon microscopy (TP) and second harmonic generation (SHG). In the third set, physical modifications after I-CXL and C-CXL were evaluated by stress-strain measurements and by studying corneal resistance against collagenase digestion. Based on HPLC analysis, we found that iontophoresis allowed riboflavin diffusion with 2-fold less riboflavin concentration than conventional application (936.2 ± 312.5 and 1708 ± 908.3 ng/mL, respectively, P riboflavin delivery in crosslinking treatments, preserving the epithelium.

  14. A novel collagen film with micro-rough surface structure for corneal epithelial repair fabricated by freeze drying technique

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    Liu, Yang; Ren, Li; Wang, Yingjun

    2014-01-01

    Highlights: • Collagen film with micro-rough surface is fabricated by freeze drying technique. • The film has suitable water uptake capability and toughness performance. • The film has good optical performance. • Human corneal epithelial cells studies confirmed the biocompatibility of the film. - Abstract: Corneal epithelial defect is a common disease and keratoplasty is a common treatment method. A collagen film with micro-rough surface was fabricated through a simple freeze drying technique in this study. Compared with the air-dried collagen film (AD-Col), this freeze-dried collagen film (FD-Col) has a more suitable water uptake capability (about 85.5%) and toughness performance. Both of the two films have good optical properties and the luminousness of them is higher than 80%. Besides, the adhesion and proliferation rate of human corneal epithelial cells on the micro-rough surface of FD-Col film is higher than that on the smooth surface of AD-Col film. The results indicate that this FD-Col film may have potential applications for corneal epithelial repair

  15. A novel collagen film with micro-rough surface structure for corneal epithelial repair fabricated by freeze drying technique

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    Liu, Yang [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); National Engineering Research Center for Tissue Restoration and Reconstruction, Guangzhou 510006 (China); Guangdong Province Key Laboratory of Biomedical Engineering, South China University of Technology, Guangzhou 510006 (China); Ren, Li, E-mail: psliren@scut.edu.cn [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); National Engineering Research Center for Tissue Restoration and Reconstruction, Guangzhou 510006 (China); Guangdong Province Key Laboratory of Biomedical Engineering, South China University of Technology, Guangzhou 510006 (China); Wang, Yingjun, E-mail: imwangyj@163.com [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); National Engineering Research Center for Tissue Restoration and Reconstruction, Guangzhou 510006 (China); Guangdong Province Key Laboratory of Biomedical Engineering, South China University of Technology, Guangzhou 510006 (China)

    2014-05-01

    Highlights: • Collagen film with micro-rough surface is fabricated by freeze drying technique. • The film has suitable water uptake capability and toughness performance. • The film has good optical performance. • Human corneal epithelial cells studies confirmed the biocompatibility of the film. - Abstract: Corneal epithelial defect is a common disease and keratoplasty is a common treatment method. A collagen film with micro-rough surface was fabricated through a simple freeze drying technique in this study. Compared with the air-dried collagen film (AD-Col), this freeze-dried collagen film (FD-Col) has a more suitable water uptake capability (about 85.5%) and toughness performance. Both of the two films have good optical properties and the luminousness of them is higher than 80%. Besides, the adhesion and proliferation rate of human corneal epithelial cells on the micro-rough surface of FD-Col film is higher than that on the smooth surface of AD-Col film. The results indicate that this FD-Col film may have potential applications for corneal epithelial repair.

  16. Scleral lens tolerance after corneal cross-linking for keratoconus

    NARCIS (Netherlands)

    Visser, Esther Simone; Soeters, Nienke; Tahzib, Nayyirih G.

    2015-01-01

    Purpose. Subjective and objective evaluation of scleral lens tolerance and fitting before and after corneal cross-linking (CXL) for progressive keratoconus. Methods. In this prospective cohort, evaluations were made of 18 unilateral eyes in patients who underwent CXL and had been wearing scleral

  17. Microscopic characterization of collagen modifications induced by low-temperature diode-laser welding of corneal tissue.

    Science.gov (United States)

    Matteini, Paolo; Rossi, Francesca; Menabuoni, Luca; Pini, Roberto

    2007-08-01

    Laser welding of corneal tissue that employs diode lasers (810 nm) at low power densities (12-20 W/cm(2)) in association with Indocyanine Green staining of the wound is a technique proposed as an alternative to conventional suturing procedures. The aim of this study is to evaluate, by means of light (LM) and transmission electron microscopy (TEM) analyses, the structural modifications induced in laser-welded corneal stroma. Experiments were carried out in 20 freshly enucleated pig eyes. A 3.5 mm in length full-thickness cut was produced in the cornea, and was then closed by laser welding. Birefringence modifications in samples stained with picrosirius red dye were analyzed by polarized LM to assess heat damage. TEM analysis was performed on ultra-thin slices, contrasted with uranyl acetate and lead citrate, in order to assess organization and size of type I collagen fibrils after laser welding. LM evidenced bridges of collagen bundles between the wound edges, with a loss of regular lamellar organization at the welded site. Polarized LM indicated that birefringence properties were mostly preserved after laser treatment. TEM examinations revealed the presence of quasi-ordered groups of fibrils across the wound edges preserving their interfibrillar spacing. These fibrils appeared morphologically comparable to those in the control tissue, indicating that type I collagen was not denatured during the diode laser corneal welding. The preservation of substantially intact, undenatured collagen fibrils in laser-welded corneal wounds supported the thermodynamic studies that we carried out recently, which indicated temperatures below 66 degrees C at the weld site under laser irradiation. This observation enabled us to hypothesize that the mechanism, proposed in the literature, of unwinding of collagen triple helixes followed by fibrils "interdigitation" is not likely to occur in the welding process that we set up for the corneal suturing.

  18. Collagen VII deficient mice show morphologic and histologic corneal changes that phenotypically mimic human dystrophic epidermolysis bullosa of the eye.

    Science.gov (United States)

    Chen, Vicki M; Shelke, Rajani; Nyström, Alexander; Laver, Nora; Sampson, James F; Zhiyi, Cao; Bhat, Najma; Panjwani, Noorjahan

    2018-06-16

    Absence of collagen VII causes blistering of the skin, eyes and many other tissues. This disease is termed dystrophic epidermolysis bullosa (DEB). Corneal fibrosis occurs in up to 41% and vision loss in up to 64% of patients. Standard treatments are supportive and there is no cure. The immune-histologic and morphologic changes in the corneas of the mouse model for this disease have not been described in the literature. Our purpose is to characterize the eyes of these mice to determine if this is an appropriate model for study of human therapeutics. Western blot analysis (WB) and immunohistochemistry (IHC) were performed to assess the relative collagen VII protein levels and its location within the cornea. Additional IHC for inflammatory and fibrotic biomarkers alpha-smooth muscle actin (α-SMA), transforming growth factor-beta (TGF-β), connective tissue growth factor (CTGF), proteinase 3, tenascin C and collagen III were performed. Clinical photographs documenting opacification of the corneas of animals of differing ages were assessed and scored independently by 2 examiners. Histology was then used to investigate morphologic changes. IHC and WB confirmed that these mice are deficient in collagen VII production at the level of the basement membrane when compared with wild-types. IHC showed anomalous deposition of collagen III throughout the stroma. Of the 5 biomarkers tested, TGF-β showed the strongest and most consistently staining. Photographs documented corneal opacities only in mice older than 10 weeks, opacities were not seen in younger animals. Histology showed multiple abnormalities, including epithelial hyperplasia, ulceration, fibrosis, edema, dysplasia, neovascularization and bullae formation. The collagen VII hypomorphic mouse shows reduced collagen VII production at the level of the corneal basement membrane. Corneal changes are similar to pathology seen in humans with this disease. The presence of anomalous stromal collagen III and TGF-β appear to be

  19. The theory and art of corneal cross-linking.

    Science.gov (United States)

    McQuaid, Rebecca; Cummings, Arthur B; Mrochen, Michael

    2013-08-01

    Before the discovery of corneal cross-linking (CXL), patients with keratoconus would have had to undergo corneal transplantation, or wear rigid gas permeable lenses (RGPs) that would temporarily flatten the cone, thereby improving the vision. The RGP contact lens (CL) would not however alter the corneal stability and if the keratoconus was progressive, the continued steepening of the cone would occur under the RGP CL. To date, the Siena Eye has been the largest study to investigate long term effects of standard CXL. Three hundred and sixty-three eyes were treated and monitored over 4 years, producing reliable long-term results proving long-term stability of the cornea by halting the progression of keratoconus, and proving the safety of the procedure. Traditionally, CXL requires epithelial removal prior to corneal soakage of a dextran-based 0.1% riboflavin solution, followed by exposure of ultraviolet-A (UV-A) light for 30 min with an intensity of 3 mW/cm2. A series of in vitro investigations on human and porcine corneas examined the best treatment parameters for standard CXL, such as riboflavin concentration, intensity, wavelength of UV-A light, and duration of treatment. Photochemically, CXL is achieved by the generation of chemical bonds within the corneal stroma through localized photopolymerization, strengthening the cornea whilst minimizing exposure to the surrounding structures of the eye. In vitro studies have shown that CXL has an effect on the biomechanical properties of the cornea, with an increased corneal rigidity of approximately 70%. This is a result of the creation of new chemical bonds within the stroma.

  20. The theory and art of corneal cross-linking

    Directory of Open Access Journals (Sweden)

    Rebecca McQuaid

    2013-01-01

    Full Text Available Before the discovery of corneal cross-linking (CXL, patients with keratoconus would have had to undergo corneal transplantation, or wear rigid gas permeable lenses (RGPs that would temporarily flatten the cone, thereby improving the vision. The RGP contact lens (CL would not however alter the corneal stability and if the keratoconus was progressive, the continued steepening of the cone would occur under the RGP CL. To date, the Siena Eye has been the largest study to investigate long term effects of standard CXL. Three hundred and sixty-three eyes were treated and monitored over 4 years, producing reliable long-term results proving long-term stability of the cornea by halting the progression of keratoconus, and proving the safety of the procedure. Traditionally, CXL requires epithelial removal prior to corneal soakage of a dextran-based 0.1% riboflavin solution, followed by exposure of ultraviolet-A (UV-A light for 30 min with an intensity of 3 mW/cm2. A series of in vitro investigations on human and porcine corneas examined the best treatment parameters for standard CXL, such as riboflavin concentration, intensity, wavelength of UV-A light, and duration of treatment. Photochemically, CXL is achieved by the generation of chemical bonds within the corneal stroma through localized photopolymerization, strengthening the cornea whilst minimizing exposure to the surrounding structures of the eye. In vitro studies have shown that CXL has an effect on the biomechanical properties of the cornea, with an increased corneal rigidity of approximately 70%. This is a result of the creation of new chemical bonds within the stroma.

  1. Highly concentrated collagen solutions leading to transparent scaffolds of controlled three-dimensional organizations for corneal epithelial cell colonization.

    Science.gov (United States)

    Tidu, Aurélien; Ghoubay-Benallaoua, Djida; Teulon, Claire; Asnacios, Sophie; Grieve, Kate; Portier, François; Schanne-Klein, Marie-Claire; Borderie, Vincent; Mosser, Gervaise

    2018-05-29

    This study aimed at controlling both the organization and the transparency of dense collagen scaffolds making use of the lyotropic mesogen properties of collagen. Cholesteric or plywood-like liquid crystal phases were achieved using mixtures of acetic and hydrochloric acids as solvents. The critical pH at which the switch between the two phases occurred was around pH = 3. The use of the two acids led to fibrillated collagen I scaffolds, whose visual aspect ranged from opaque to transparent. Rheological investigations showed that viscoelastic properties of the plywood-like solutions were optimized for molding due to faster recovery. They also confirmed the correlation between the elastic modulus and the diameter of collagen fibrils obtained after fibrillogenesis under ammonia vapor. Human corneal epithelial cells, grown from donor limbal explants, were cultured both on transparent plywood-like matrices and on human amniotic membranes for 14 days. The development of corneal epithelium and the preservation of epithelial stem cells were checked by optical microscopy, colony formation assay, immuno-fluorescence and quantitative polymerase chain reaction. A higher level of amplification of limbal stem cells was obtained with collagen matrices compared with amniotic membranes, showing the high biocompatibility of our scaffolds. We therefore suggest that collagen solutions presenting both plywood-like organization and transparency might be of interest for biomedical applications in ophthalmology.

  2. Algorithm for Correcting the Keratometric Error in the Estimation of the Corneal Power in Keratoconus Eyes after Accelerated Corneal Collagen Crosslinking

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    David P. Piñero

    2017-01-01

    Full Text Available Purpose. To analyze the errors associated to corneal power calculation using the keratometric approach in keratoconus eyes after accelerated corneal collagen crosslinking (CXL surgery and to obtain a model for the estimation of an adjusted corneal refractive index nkadj minimizing such errors. Methods. Potential differences (ΔPc among keratometric (Pk and Gaussian corneal power (PcGauss were simulated. Three algorithms based on the use of nkadj for the estimation of an adjusted keratometric corneal power (Pkadj were developed. The agreement between Pk1.3375 (keratometric power using the keratometric index of 1.3375, PcGauss, and Pkadj was evaluated. The validity of the algorithm developed was investigated in 21 keratoconus eyes undergoing accelerated CXL. Results. Pk1.3375 overestimated corneal power between 0.3 and 3.2 D in theoretical simulations and between 0.8 and 2.9 D in the clinical study (ΔPc. Three linear equations were defined for nkadj to be used for different ranges of r1c. In the clinical study, differences between Pkadj and PcGauss did not exceed ±0.8 D nk=1.3375. No statistically significant differences were found between Pkadj and PcGauss (p>0.05 and Pk1.3375 and Pkadj (p<0.001. Conclusions. The use of the keratometric approach in keratoconus eyes after accelerated CXL can lead to significant clinical errors. These errors can be minimized with an adjusted keratometric approach.

  3. A role for topographic cues in the organization of collagenous matrix by corneal fibroblasts and stem cells.

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    Dimitrios Karamichos

    Full Text Available Human corneal fibroblasts (HCF and corneal stromal stem cells (CSSC each secrete and organize a thick stroma-like extracellular matrix in response to different substrata, but neither cell type organizes matrix on tissue-culture polystyrene. This study compared cell differentiation and extracellular matrix secreted by these two cell types when they were cultured on identical substrata, polycarbonate Transwell filters. After 4 weeks in culture, both cell types upregulated expression of genes marking differentiated keratocytes (KERA, CHST6, AQP1, B3GNT7. Absolute expression levels of these genes and secretion of keratan sulfate proteoglycans were significantly greater in CSSC than HCF. Both cultures produced extensive extracellular matrix of aligned collagen fibrils types I and V, exhibiting cornea-like lamellar structure. Unlike HCF, CSSC produced little matrix in the presence of serum. Construct thickness and collagen organization was enhanced by TGF-ß3. Scanning electron microscopic examination of the polycarbonate membrane revealed shallow parallel grooves with spacing of 200-300 nm, similar to the topography of aligned nanofiber substratum which we previously showed to induce matrix organization by CSSC. These results demonstrate that both corneal fibroblasts and stromal stem cells respond to a specific pattern of topographical cues by secreting highly organized extracellular matrix typical of corneal stroma. The data also suggest that the potential for matrix secretion and organization may not be directly related to the expression of molecular markers used to identify differentiated keratocytes.

  4. Characterization of elasticity and hydration of composite hydrogel based on collagen-iota carrageenan as a corneal tissue engineering

    Science.gov (United States)

    Rinawati, M.; Triastuti, J.; Pursetyo, K. T.

    2018-04-01

    The cornea is a refractive element of the eye that serves to continue the stimulation of light into the eye it has a clear, transparent, elastic and relatively thick tissue. Factors caused corneal blindness, are dystrophy, keratoconus, corneal scaring. Hydrogels can be made from polysaccharide derivatives that have gelation properties such as iota carrageenan. Therefore, it is a need to develop composite hydrogel based collagen-iota carragenan as an engineeried corneal tissue with high elasticity and hydration properties. Collagen hydrogel has a maximum water content an has equlibrium up to 40 %, less than the human cornea, 81 % and under normal hydration conditions, the human cornea can transmit 87 % of visible light. In addition, the refractive index on the surface of the cornea with air is 1.375-1.380. Based on this study, it is necessary to conduct research on the development and composition of hydrogel composite collagen-iota carrageen hydrogen based on. The best result was K5 (5:5) treatment, which has the equilibrium water content of 87.07 % and viscosity of 10.7346 Pa.s.

  5. Topographic outcomes after corneal collagen crosslinking in progressive keratoconus: 1-year follow-up

    Directory of Open Access Journals (Sweden)

    Mauro C. Tiveron Jr

    Full Text Available ABSTRACT Purpose: We aimed to report and analyze topographic and refractive outcomes following corneal collagen crosslinking (CXL in patients with progressive keratoconus (KC. Methods: We performed a retrospective, analytical, and observational study of 100 eyes from 74 progressive KC patients who underwent CXL at the Eye Hospital of Paraná. Keratometric values were analyzed preoperatively as well as 3 and 12 months postoperatively. Results: For a total of 100 eyes, 68 belonged to male patients. The mean age of our study population was 19.9 ± 5.61 years. The average visual acuity and topographic parameters overall were stable after 1 year (p<0.05. After 3 months, steepest keratometry reading (K2 and maximum keratometry (Kmax were significantly decreased (p<0.05. Regarding topographic astigmatism (dK, there was no significant difference between the 3-month and 12-month follow-ups. When we made comparisons between genders following CXL, there were no significant differences related to the changes in Kmax, K2, and spectacle-corrected distance visual acuity (SCDVA. Conclusions: CXL promoted stabilization or improvement of keratometric values and visual acuity. We found that keratoconus apex stability may be achieved 3 months after the procedure. There was no significant difference in keratometric and refractive values measured between male and female patients.

  6. Corneal Collagen Crosslinking Combined with Phototherapeutic Keratectomy and Photorefractive Keratectomy for Corneal Ectasia after Laser in situ Keratomileusis.

    Science.gov (United States)

    Zhu, Wei; Han, Yunfei; Cui, Changxia; Xu, Wenwen; Wang, Xuan; Dou, Xiaoxiao; Xu, Linlin; Xu, Yanyun; Mu, Guoying

    2018-01-01

    The aim of this study was to analyze the effects of corneal crosslinking (CXL) combined with phototherapeutic keratectomy (PTK) and photorefractive keratectomy (PRK) in halting the progression and improving the visual function of corneal ectasia after laser in situ keratomileusis (LASIK). PTK-PRK-CXL was performed on 14 eyes of 14 patients who developed corneal ectasia after LASIK. The visual acuity, spherical refraction and cylinder, corneal topography indices, thinnest corneal thickness (TCT), and endothelial cell count were evaluated at baseline and at 1, 3, 6, and 12 months postoperatively. The mean uncorrected visual acuity improved significantly from 0.64 ± 0.36 logMAR preoperatively to 0.19 ± 0.12 logMAR at 12 months of follow-up (p 0.05) beyond 6 months after treatment. PTK-PRK-CXL is a promising procedure to halt the progression of post-LASIK keratectasia with significant visual quality improvement. © 2018 S. Karger AG, Basel.

  7. Chitosan Cross-linked Reconstituted Amniotic Collagen Membrane ...

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Chitosan Cross-linked Reconstituted Amniotic Collagen Membrane – An Excellent Cell Substratum. The KERATINOCYTE proliferation and Differentiation into multiple layers is due to the presence of type - IV collagen in the amnion. Cultured FIBROBLASTS had good ...

  8. Novel myopic refractive correction with transepithelial very high-fluence collagen cross-linking applied in a customized pattern: early clinical results of a feasibility study

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    Kanellopoulos AJ

    2014-04-01

    Full Text Available Anastasios John Kanellopoulos LaserVision.gr Institute, Athens, Greece, and New York Medical School, New York, NY, USA Background: The purpose of this study is to report the safety and efficacy of a new application of collagen cross-linking using a novel device to achieve predictable refractive myopic changes in virgin corneas. Methods: Four cases were treated with a novel device employing very high-fluence collagen cross-linking applied in a myopic pattern. Prior to treatment, riboflavin solution was applied to the intact epithelium. The collagen cross-linking device was then engaged for a total of 12 J/cm2, to be applied transepithelially in a predetermined pattern. Cornea clarity, corneal keratometry, and corneal topography were evaluated by both Placido disc and Scheimpflug imaging, along with cornea anterior segment optical coherence tomography and endothelial cell counts. Results: An average of 2.3 diopters was achieved in the first week in all four cases treated with the very high-fluence myopic collagen cross-linking intervention. There was a slight regression to 1.44 diopters at 1 month, which remained stable at 6-month follow-up. The mean keratometry change was from 44.90 diopters to 43.46 diopters. There was no significant change in endothelial cell counts or corneal clarity. There was some mild change in epithelial thickness distribution, with the treated area showing a slight but homogeneous reduction in mean thickness from 52 µm to 44 µm. Conclusion: This report describes the novel application of very high-fluence collagen cross-linking with a predictable well defined myopic refractive (flattening corneal effect. This technique has the advantages of essentially no postoperative morbidity, immediate visual rehabilitation, and the potential for tapering until the desired result is achieved. Keywords: myopia, refractive correction, high-fluence collagen cross-linking, clinical results

  9. Development of a human corneal epithelium model utilizing a collagen vitrigel membrane and the changes of its barrier function induced by exposing eye irritant chemicals.

    Science.gov (United States)

    Takezawa, Toshiaki; Nishikawa, Kazunori; Wang, Pi-Chao

    2011-09-01

    The brief TEER (trans-epithelial electrical resistance) assay after exposing chemicals to corneal epithelium in vivo is known as a suitable method for evaluating corneal irritancy and permeability quantitatively and continuously. A collagen vitrigel membrane we previously developed is a thin (about 20 μm thick) and transparent membrane composed of high density collagen fibrils equivalent to connective tissues in vivo, e.g. corneal Bowman's membrane. To develop such a TEER assay system in vitro utilizing a human corneal epithelial model, HCE-T cells (a human corneal epithelial cell line) were cultured on the collagen vitrigel membrane substratum prepared in a Millicell chamber suitable for TEER measurement. Human corneal epithelium model possessing 5-6 cell layers sufficient for TEER assay was successfully reconstructed on the substratum in the Millicell chamber by culturing the cells in monolayer for 2 days and subsequently in air-liquid interface for 7 days. The exposure of chemicals to the model induced the time-dependent relative changes of TEER in response to the characteristic of each chemical within a few minutes. These results suggest that the TEER assay using the human corneal epithelial model is very useful for an ocular irritancy evaluation as an alternative to the Draize eye irritation test. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Primary Outcomes of Accelerated Epithelium-Off Corneal Cross-Linking in Progressive Keratoconus in Children: A 1-Year Prospective Study

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    Sherif A. Eissa

    2017-01-01

    Full Text Available Purpose. To evaluate corneal transparency following accelerated collagen cross-linking (ACXL in pediatric keratoconus. Design. A prospective interventional case series. Methods. This study included 47 eyes (25 patients, aged 9–14 years, with documented progressive keratoconus. After applying 0.1% riboflavin drops, ACXL was performed. Assessment included corrected distance visual acuity (CDVA, uncorrected visual acuity (UCVA, corneal haze, and corneal densitometry in grayscale units (GSU. Result. The mean baseline and corneal densitometry peaked at 3 months post-ACXL while central and posterior densitometry showed a statistically significant increase (P<0.05 and peaked at 8 months postoperatively. By 12 months, densitometry in all corneal layers (P≥0.99 and concentric zones (P≥0.97 reached near baseline values. Slit-lamp graded haze peaked at 1 month to 1.82 ± 0.65 (P<0.05 and declined to near baseline at 12 months (0.39 ± 0.58. There was a statistically significant increase in the mean UCVA and CDVA at 12 months. Conclusion. Total and anterior corneal densitometry peaked after 3 months, while central and posterior densitometry peaked after 8 months. Maximum haze was at 1 month post-ACXL. All corneal layers, concentric zone densitometry and haze reached near baseline values after 1 year. Scheimpflug densitometry showed weak correlation with CDVA over the 12-month follow-up period (r=−0.193.

  11. Peripheral hepatic arterial embolization with cross-linked collagen fibers

    International Nuclear Information System (INIS)

    Daniels, J.R.; Kerlan, R.K. Jr.; Dodds, L.; McLaughlin, P.; La Berge, J.M.; Harrington, D.; Daniels, A.M.; Ring, E.J.

    1986-01-01

    Hepatic artery embolization with a nonimmunogenic, cross-linked collagen preparation (Angiostat, collagen for embolization, Target Therapeutics) was studied in mongrel dogs. Flow-directed technique was used to achieve complete distal arterial occlusion. Serial liver function evaluation demonstrated marked alterations at 48 to 72 hours, partial correction at 1 week, and resolution of abnormalities by 1 month. Restoration of large-vessel blood flow was angiographically demonstrable at 1 week. Recanalization, achieved by migration of endothelial cells around the collagen, resulted in complete restoration of normal hepatic vascular and tissue anatomy at 1 month. Repeated embolization at biweekly intervals was well tolerated

  12. Large proteoglycan complexes and disturbed collagen architecture in the corneal extracellular matrix of mucopolysaccharidosis type VII (Sly syndrome).

    Science.gov (United States)

    Young, Robert D; Liskova, Petra; Pinali, Christian; Palka, Barbara P; Palos, Michalis; Jirsova, Katerina; Hrdlickova, Enkela; Tesarova, Marketa; Elleder, Milan; Zeman, Jiri; Meek, Keith M; Knupp, Carlo; Quantock, Andrew J

    2011-08-24

    Deficiencies in enzymes involved in proteoglycan (PG) turnover underlie a number of rare mucopolysaccharidoses (MPS), investigations of which can considerably aid understanding of the roles of PGs in corneal matrix biology. Here, the authors analyze novel pathologic changes in MPS VII (Sly syndrome) to determine the nature of PG-collagen associations in stromal ultrastructure. Transmission electron microscopy and electron tomography were used to investigate PG-collagen architectures and interactions in a cornea obtained at keratoplasty from a 22-year-old man with MPS VII, which was caused by a compound heterozygous mutation in the GUSB gene. Transmission electron microscopy showed atypical morphology of the epithelial basement membrane and Bowman's layer in MPS VII. Keratocytes were packed with cytoplasmic vacuoles containing abnormal glycosaminoglycan (GAG) material, and collagen fibrils were thinner than in normal cornea and varied considerably throughout anterior (14-32 nm), mid (13-42 nm), and posterior (17-39 nm) regions of the MPS VII stroma. PGs viewed in three dimensions were striking in appearance in that they were significantly larger than PGs in normal cornea and formed highly extended linkages with multiple collagen fibrils. Cellular changes in the MPS VII cornea resemble those in other MPS. However, the wide range of collagen fibril diameters throughout the stroma and the extensive matrix presence of supranormal-sized PG structures appear to be unique features of this disorder. The findings suggest that the accumulation of stromal chondroitin-, dermatan-, and heparan-sulfate glycosaminoglycans in the absence of β-glucuronidase-mediated degradation can modulate collagen fibrillogenesis.

  13. Effect of the Regenerative Agent Poly(Carboxymethylglucose Sulfate) on Corneal Wound Healing After Corneal Cross-Linking for Keratoconus.

    Science.gov (United States)

    Kymionis, George D; Liakopoulos, Dimitrios A; Grentzelos, Michael A; Tsoulnaras, Konstantinos I; Detorakis, Efstathios T; Cochener, Béatrice; Tsilimbaris, Miltiadis K

    2015-08-01

    To evaluate the effect of a regenerative agent (RGTA) [Cacicol20-poly(carboxymethyl glucose sulfate); OTR3, Paris, France] on corneal reepithelialization and pain after corneal cross-linking (CXL) for keratoconus. In this prospective comparative (contralateral) clinical study, patients with bilateral progressive keratoconus underwent CXL treatment. The corneal epithelium during CXL was removed using transepithelial phototherapeutic keratectomy (Cretan protocol). One eye of each patient was randomly instilled with an RGTA (Cacicol20) once a day (study group), whereas the fellow eye was instilled with artificial tears (control group). Patients were examined daily until complete reepithelialization. Postoperative examinations included slit-lamp biomicroscopy to assess the epithelial defect size and subjective evaluation of pain. The study enrolled 18 patients (36 eyes). The mean epithelial defect size for study and control groups was 19.6 ± 4.2 mm versus 21.5 ± 2.8 mm, respectively, at day 1 (P = 0.019) and 6.4 ± 3.4 mm versus 7.9 ± 4.3 mm, respectively, at day 2 (P = 0.014). At day 3 postoperatively, 61.1% of study eyes were fully reepithelialized, compared with 11.1% of control eyes (P = 0.002). RGTA (Cacicol20) instillation seems to result in faster corneal reepithelialization after CXL in this study. However, there was no significant effect in subjective pain/discomfort.

  14. A study comparing standard and transepithelial collagen cross-linking riboflavin solutions: epithelial findings and pain scores.

    Science.gov (United States)

    Yuksel, Erdem; Novruzlu, Shahin; Ozmen, Mehmet C; Bilgihan, Kamil

    2015-06-01

    To evaluate epithelial signs and pain after epithelial-on corneal collagen cross-linking (Epi-on CCL) with new transepithelial riboflavin formulation and epithelial-off corneal collagen cross-linking (Epi-off CCL) with standard riboflavin formulation and to compare pain and duration of epithelial healing between both techniques. Thirty-nine eyes of 39 patients undergoing Epi-on CCL and 39 eyes of 39 patients undergoing Epi-off CCL were evaluated. Corneal epithelial signs and durations of corneal epithelial healing and subjective pain scores after the procedures were recorded and compared between 2 groups. Total epithelialization was observed after 2.7 ± 0.7 days in Epi-on CCL and 2.3 ± 0.4 days in Epi-off CCL (P = 0.006). The mean pain score on the first day was 3.1 ± 0.6 in Epi-on CCL and 2.3 ± 0.4 in Epi-off CCL with a significant difference (P = 0.0001). The epithelial damage was observed in both procedures; also, the epithelial healing time was longer in Epi-on CCL and it is of great importance that the patients should have therapeutic contact lenses until the epithelium heals in both procedures. The Epi-off CCL group had less pain scores than the Epi-on CCL group and more pain problems after Epi-on CCL still remains. The patient should be informed about pain, even if the Epi-on CCL procedure was performed.

  15. Combined application of prophylactic corneal cross-linking and laser in-situ keratomileusis - a review of literature.

    Science.gov (United States)

    Chan, Tommy C Y; Ng, Alex L K; Chan, Karen K W; Cheng, George P M; Wong, Ian Y H; Jhanji, Vishal

    2017-11-01

    Laser in-situ keratomileusis (LASIK) is safe and effective laser refractive procedures in treating refractive errors. However, regression of treatment and iatrogenic keratectasia remain to be a major concern, especially in treating thin cornea with high ametropia. Collagen cross-linking (CXL) is an effective method in stopping keratoconus progression through increasing the biomechanical strength of the cornea. Adjuvant cross-linking to refractive procedures can theoretically help prevent regression and reduce the risk of keratectasia development by increasing the mechanical stability of cornea. During the procedure, riboflavin is directly applied to the corneal stroma, thereby reducing the need of de-epithelialization as in the conventional protocol for keratoconus. Currently, there is still no consensus regarding the indication of CXL during refractive procedure, nor any standardized treatment protocol. This article aims to summarize the current evidence regarding the use of adjuvant CXL in LASIK. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  16. Changes in corneal sensitivity following cross-linking for progressive early-stage keratoconus

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    Anelise de Medeiros Lago

    2014-04-01

    Full Text Available Purpose: To evaluate changes in corneal sensitivity following corneal cross-linking (CXL in patients with progressive earlier stage keratoconus. Methods: Thirty-eight eyes of 19 patients (11 women, 8 men were included in a prospective, nonrandomized clinical study. The mean patient age was 22 years (range, 18-26 years. Inclusion criteria were early stage bilateral progressive keratoconus, a transparent cornea, and a thickness of ≥440 µm in the thinnest area of the cornea. Using the Cochet-Bonnet esthesiometer, central corneal sensitivity was measured before surgery, 7 days after surgery, and once a month thereafter until recovery of baseline preoperative levels. Central corneal sensitivity >40 mm was considered normal. Results: Corneal sensitivity gradually returned to preoperative levels in all treated eyes. The mean central corneal sensitivity was 52.2, 24.0, 38.2, 42.5, 50.0, and 52.5 mm before surgery, 7 days after surgery, and at 1, 2, 3, and 4 months after surgery, respectively. Normal levels of corneal sensation, but not baseline (preoperative levels, were observed 2 months after surgery. The preoperative levels were observed 3 months after surgery. Conclusions: Our results suggest that central corneal sensitivity can be decreased for as long as 3 months after CXL for progressive earlier stage keratoconus.

  17. Efectividad del crosslinking del colágeno corneal en el tratamiento del queratocono Effectiveness of the corneal collagen crosslinking in the treatment of keratoconus

    Directory of Open Access Journals (Sweden)

    Madelyn Jareño Ochoa

    2012-12-01

    Full Text Available Objetivo: determinar la efectividad del tratamiento de crosslinking del colágeno corneal en pacientes con queratocono progresivo en el Instituto Cubano de Oftalmología "Ramón Pando Ferrer". Métodos: estudio descriptivo, retrospectivo, en 30 pacientes (30 ojos con queratocono progresivo que se les realizó el crosslinking del colágeno corneal. Se recogieron los datos en el preoperatorio, al mes, 3 meses, 6 meses y al año. Las variables estudiadas fueron: edad, sexo, estadio del queratocono, mejor agudeza visual corregida, equivalente esférico, queratometría máxima topográfica, algunos índices topográficos de diagnóstico de queratocono, el coma y la paquimetría óptica. Resultados: predominó el sexo femenino, grupo de 20 a 29 años de edad y el estadio II del queratocono. La mejor agudeza visual corregida se incrementa de 0,65 ±0,25 en el preoperatorio a 0,74 ±0,23 al año. El equivalente esférico disminuye de -7,25 ±4,48 a -6,39 ±4,20 dioptrías. La queratometría máxima topográfica de 50,76 ±3,81 a 49,26 ±3,31 dioptrías. Los índices topográficos disminuyeron sus valores. El error cuadrático medio del coma se modificó de 0,59 ±0,43 a 0,45 ±0,32 micras. La paquimetría óptica del centro de la pupila varió de 494 ±39,75 a 466 ±44,24 micras y la de la posición más delgada de 484 ±45,86 a 450 ±51,12 micras. Todos los resultados al año mostraron diferencias estadísticamente significativas. Conclusiones: el crosslinking es un tratamiento efectivo para el queratocono progresivo que permite detener la evolución de esta enfermedad ectásica.Objective: to determine the effectiveness of corneal collagen crosslinking in patients with progressive keratoconus performed at “Ramón Pando Ferrer” Cuban Institute of Ophthalmology. Methods: a retrospective and descriptive study was performed in 30 patients (30 eyes with progressive keratoconus, who underwent the corneal collagen crosslinking. Data were collected

  18. Effect of corneal cross-linking on contact lens tolerance in keratoconus.

    Science.gov (United States)

    Ünlü, Metin; Yüksel, Erdem; Bilgihan, Kamil

    2017-07-01

    The aim was to investigate changes in corneal sensation and rigid gas-permeable (RGP) contact lens tolerance after corneal cross-linking (CXL) on patients with keratoconus. Thirty eyes of 30 patients, who were RGP lens intolerant, were treated with CXL. The main outcome measures were corneal sensation evaluation by Cochet-Bonnet esthesiometry, sub-basal nerve fibre assessment by corneal in vivo confocal microscopy and RGP contact lens tolerance evaluation with the Likert scale and wearing time. All eyes were evaluated preoperatively and post-operatively at one, three and six months after CXL procedure. The mean age was 25.3 ± 6.2 years. Preoperatively, the maximum keratometry (Kmax) in study eyes was 56.89 ± 4.60 D. Six months after CXL, it reduced to 56.03 ± 4.85 D (p = 0.01). Preoperative mean corneal sensation was 0.44 ± 0.05 g/mm 2 , (range: 0.40 to 0.55); it was significantly decreased at the first month and increased to preoperative values after six months. The sub-basal nerve plexus could not be visualised in 90 per cent of the patients by confocal microscopy at one month post-operatively. Gradual restoration of corneal innervation with almost similar preoperative levels at post-operative month six was noted. There were significant differences in Likert scores between preoperative and third and sixth months after CXL. Likert scale scores correlated significantly with corneal sensitivity. It can be concluded that increased RGP contact lens tolerance after CXL may be associated with the potential role of decreased corneal sensitivity and corneal flattening after CXL. © 2016 Optometry Australia.

  19. Topography-guided transepithelial PRK after intracorneal ring segments implantation and corneal collagen CXL in a three-step procedure for keratoconus.

    Science.gov (United States)

    Coskunseven, Efekan; Jankov, Mirko R; Grentzelos, Michael A; Plaka, Argyro D; Limnopoulou, Aliki N; Kymionis, George D

    2013-01-01

    To present the results of topography-guided transepithelial photorefractive keratectomy (PRK) after intracorneal ring segments implantation followed by corneal collagen cross-linking (CXL) for keratoconus. In this prospective case series, 10 patients (16 eyes) with progressive keratoconus were included. All patients underwent topography-guided transepithelial PRK after Keraring intracorneal ring segments (Mediphacos Ltda) implantation, followed by CXL treatment. The follow-up period was 6 months after the last procedure for all patients. Time interval between both intracorneal ring segments implantation and CXL and between CXL and topography-guided transepithelial PRK was 6 months. LogMAR mean uncorrected distance visual acuity and mean corrected distance visual acuity were significantly improved (PPRK with intracorneal ring segments implantation and CXL in a three-step procedure seems to be an effective, promising treatment sequence offering patients a functional visual acuity and ceasing progression of the ectatic disorder. A longer follow-up and larger case series are necessary to thoroughly evaluate safety, stability, and efficacy of this innovative procedure. Copyright 2013, SLACK Incorporated.

  20. AN ANALYTICAL STUDY OF EFFICACY OF CORNEAL COLLAGEN CROSSLINKING C3R PROCEDURE IN PROGRESSIVE KERATOCONUS PATIENTS

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    Rajasekar K

    2017-10-01

    Full Text Available BACKGROUND Keratoconus affects a significant number of the general population with conical weakened protruded area from the cornea due to weakening of the corneal stroma by a genetically premeditated preponderance. We see keratoconus as a standalone disease or accompanying other syndrome manifestations in patients. Mainly, the inferotemporal cornea is affected and the conical protrusion causes profound high irregular myopic astigmatism as a refractive error, which is very difficult to correct in progressed advanced stages. Especially in economically productive age group patients, the poor vision becomes very difficult to live with. Corneal collagen crosslinking procedure is a novel tool in the armamentarium of treatment procedures against this malady. MATERIALS AND METHODS This analytical study was conducted at cornea services, Regional Institute of Ophthalmology and Government Ophthalmic Hospital, Chennai, for a period of 14 months. Forty five eyes of forty patients with early progressive keratoconus who presented to cornea services were subjected to riboflavin UVA collagen crosslinking procedures using a standard protocol after getting an informed consent. Further response to treatment were assessed in the follow up period. RESULTS Out of 40 patients in our series, 23 were males and 17 were females. The maximum patients in our series were in the age group between 10 to 25 yrs. Epi-off procedure was done in 31 eyes and epi-on procedure was done in 14 eyes. The patients with pachymetry 400-450 microns underwent epi-on procedure and more than 450 microns underwent epi-off C3R procedure. The K values in our series were between 49D to maximum 63D. The topographic flattening was seen in 52% in epi-on and epi-off procedures. Vision improvement in our series was 57% following epi-on and 65% following epi-off procedures. CONCLUSION C3R is a very promising therapeutic modality that may halt the progression of ectatic process. It is a less invasive mode

  1. Evaluation of nanohydroxyapaptite (nano-HA) coated epigallocatechin-3-gallate (EGCG) cross-linked collagen membranes.

    Science.gov (United States)

    Chu, Chenyu; Deng, Jia; Man, Yi; Qu, Yili

    2017-09-01

    Collagen is the main component of extracellular matrix (ECM) with desirable biological activities and low antigenicity. Collagen materials have been widely utilized in guided bone regeneration (GBR) surgery due to its abilities to maintain space for hard tissue growth. However, pure collagen lacks optimal mechanical properties. In our previous study, epigallocatechin-3-gallate (EGCG) cross-linked collagen membranes, with better biological activities and enhanced mechanical properties, may promote osteoblast proliferation, but their effect on osteoblast differentiation is not very significant. Nanohydroxyapatite (nano-HA) is the main component of mineral bone, which possesses exceptional bioactivity properties including good biocompatibility, high osteoconductivity and osteoinductivity, non-immunogenicity and non-inflammatory behavior. Herein, by analyzing the physical and chemical properties as well as the effects on promoting bone regeneration, we have attempted to present a novel EGCG-modified collagen membrane with nano-HA coating, and have found evidence that the novel collagen membrane may promote bone regeneration with a better surface morphology, without destroying collagen backbone. To evaluate the surface morphologies, chemical and mechanical properties of pure collagen membranes, epigallocatechin-3-gallate (EGCG) cross-linked collagen membranes, nano-HA coated collagen membranes, nano-HA coated EGCG-collagen membranes, (ii) to evaluate the bone regeneration promoted by theses membranes. In the present study, collagen membranes were divided into 4 groups: (1) untreated collagen membranes (2) EGCG cross-linked collagen membranes (3) nano-HA modified collagen membranes (4) nano-HA modified EGCG-collagen membranes. Scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to evaluate surface morphologies and chemical properties, respectively. Mechanical properties were determined by differential scanning calorimeter (DSC

  2. Corneal Resistance to Keratolysis After Collagen Crosslinking With Rose Bengal and Green Light.

    Science.gov (United States)

    Fadlallah, Ali; Zhu, Hong; Arafat, Samer; Kochevar, Irene; Melki, Samir; Ciolino, Joseph B

    2016-12-01

    The purpose of this study was to evaluate the resistance to degradation by collagenase A of corneas that have been crosslinked with Rose Bengal and green light (RGX). The ex vivo crosslinking procedure was performed on enucleated rabbit corneas. Corneas were deepithelialized after applying 30% alcohol. Corneas were stained with Rose Bengal (RB, 0.1%) for 2 minutes and then exposed to green light (532 nm) at 0.25 W/cm2 for times to deliver doses of 50, 100, 150, or 200 J/cm2 (n = 5 per group). Five corneas were pretreated with riboflavin solution (0.1% riboflavin) for 15 minutes and irradiated with ultraviolet A (UVA) light (370 nm, 3 mW/cm2) for 30 minutes. Five corneas underwent only de-epithelialization and were otherwise untreated. Five corneas were stained with RB without light exposure. The central corneas of each group was removed with a 8.5-mm trephine and incubated at 37°C in 0.3% collagenase A solution. Time to dissolution of each cornea was compared across treatments. Corneas treated with RGX were treated with light fluences of 50, 100, 150, and 200 J/cm2; these corneas dissolved completely at 8.3 ± 1.2, 11.1 ± 1.4, 12.4 ± 1.7, and 15.7 ± 1.8 hours, respectively. Corneas treated by riboflavin and UVA light dissolved at 15.7 ± 1.7 hours, and nontreated corneas dissolved at 6.1 ± 1.3 hours. Corneas treated with only RB (no green light) dissolved at 9.3 ± 1.7 hours. Compared with the untreated corneas, all of the RB groups and the riboflavin-UVA-treated group of corneas degraded statistically significantly slower than untreated corneas (P < 0.05). Crosslinking with RGX increased corneal resistance to digestion by collagenase comparable to that produced by riboflavin and UVA treatment.

  3. Intracorneal ring segments implantation followed by same-day topography-guided PRK and corneal collagen CXL in low to moderate keratoconus.

    Science.gov (United States)

    Al-Tuwairqi, Waleed; Sinjab, Mazen M

    2013-01-01

    To evaluate the safety and efficacy of intrastromal corneal ring segments (ICRS) implantation followed by same-day topography-guided photorefractive keratectomy (PRK) and ultraviolet-A/riboflavin collagen cross-linking (CXL) in patients with low to moderate keratoconus. Patients with low to moderate keratoconus and contact lens intolerance were included in the study. All patients first underwent femtosecond laser-enabled placement of ICRS (Keraring, Mediphacos) (first step). Same-day topography-guided PRK and CXL (second step) were subsequently performed in all patients after the refraction was stable (average 6 months [range: 3 to 11 months]). Thirteen eyes from 13 patients were included in the study. Based on values before the first step and 6 months after the second step, significant improvements were noted in uncorrected distance visual acuity (0.7±0.32 logMAR vs 0.08±0.08 logMAR), corrected distance visual acuity (CDVA) (0.16±0.19 logMAR vs 0.02±0.04 log-MAR), sphere (-3.65±3.08 diopters [D] vs 0.06±1.6 D), astigmatism (-3.31±1.5 D vs -0.98±0.75 D), average K (47.28±1.99 D vs 41.42±3.22 D), and coma (2.36±1.23 μm vs 1.47±0.68 μm) (PPRK/CXL may be a reasonable option for improving visual acuity in patients with low to moderate keratoconus. Copyright 2013, SLACK Incorporated.

  4. EXPERIMENTAL REPAIR OF DEEP CORNEAL DEFECTS USING A BIO-CONSTRUCT COMPRISING A COLLAGEN TYPE I MATRIX LOADED WITH BUCCAL EPITHELIAL CELLS

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    N. S. Egorova

    2017-01-01

    Full Text Available The  research  objective was  to study the  reparative effects of  the  collagen  type  I bio-construct loaded  with buccal epithelial cells, on the rabbit cornea after experimental keratectomy at various stages of treatment (on the 3rd, 7th, 14th, 3 0th days.Material  and methods.  The  experiments were  conducted on 20 rabbits  of  the  Chinchilla breed that  were  operated on cornea of both eyes aiming to inflict epithelial and stromal cornea defects. The collagen-based bio-construct bearing buccal epithelial cells was placed  over the cornea of the experimental eyes. The  cornea of the control  eyes was covered with smooth contact lens. After the surgery, a temporal blepharorrhaphy was performed and kept for 3 days. We studied macroand microscopic pattern of corneal regeneration at 3, 7, 14, and 30 days of experiment.Results. When  using the collaged-based bio-construct containing buccal epithelial cells, the complete epithelialization of the corneal defect occurred at mean 7 days earlier compared to that in the control eyes. Thus, the offered bio-construct stimulated the cell migration and proliferation at early stages of treatment (3–7 days reducing the inflammation activity.Conclusion. The bio-construct comprising a collagen type  I matrix loaded with buccal epithelial cells can provide an effective treatment option for corneal defects.

  5. Association between anterior corneal astigmatism and posterior corneal astigmatism across age groups: a cross-sectional analysis

    Directory of Open Access Journals (Sweden)

    Vijay Shetty

    2017-11-01

    Full Text Available AIM: To assess the anterior corneal astigmatism(ACAand posterior corneal astigmatism(PCApatterns across various age groups. We also evaluated the association between magnitudes and axes of the ACA and PCA across these age groups. METHODS: The present study was a cross-sectional analysis of clinical data of 381 eyes. We converted the clinical astigmatic notation to vector notation for analysis of ACA and PCA. We estimated the correlation between magnitude and axes of the ACA and PCA in the whole population and in four age groups(5-19, 20-39, 40-59, and ≥ 60y. We used random effects linear regression models for estimating the association between the magnitudes of ACA and PCA.RESULTS: The mean of the magnitude of the ACA(3.59Dand the PCA(0.50Dwas highest in children(5 to 9y. Overall, the magnitude of the ACA ranged from 0D to 10.0 Diopters(Dand the magnitude of the PCA ranged from 0 to 3.5 D. There was a significant correlation between the ACA and the PCA in the younger age group(r=0.85, PP=0.03with each unit increase in the ACA, the increase was the smallest in this age group.CONCLUSION: It will be prudent to measure the both the magnitude and axis of the PCA, particularly in those above 60y rather than rely on rule-of-thumb calculations based on ACA parameters for IOL power calculation.

  6. Collagen based film with well epithelial and stromal regeneration as corneal repair materials: Improving mechanical property by crosslinking with citric acid

    International Nuclear Information System (INIS)

    Zhao, Xuan; Liu, Yang; Li, Weichang; Long, Kai; Wang, Lin; Liu, Sa; Wang, Yingjun; Ren, Li

    2015-01-01

    Corneal disease can lead to vision loss. It has become the second greatest cause of blindness in the world, and keratoplasty is considered as an effective treatment method. This paper presents the crosslinked collagen (Col)–citric acid (CA) films developed by making use of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The results showed that the Col–CA films had necessary optical performance, water content. The collagenase resistance of CA crosslinked films was superior to that of EDC crosslinked films. And CA5 film (Col:CA:EDC:NHS = 60:3:10:10) had the best mechanical properties. Cell experiments showed that CA5 film was non-cytotoxic and human corneal epithelial cells could proliferate well on the films. Lamellar keratoplasty showed that the CA5 film could be sutured in the rabbit eyes and was epithelialized completely in about 10 days, and the transparency was restored quickly in 30 ± 5 days. No inflammation and corneal neovascularization were observed at 6 months. Corneal stroma had been repaired; stromal cells and neo-stroma could be seen in the area of operation from the hematoxylin–eosin stained histologic sections and anterior segment optical coherence tomography images. These results indicated that Col–CA films were highly promising biomaterials that could be used in corneal tissue engineering and a variety of other tissue engineering applications. - Highlights: • Adding different amounts of citric acid could change the properties of films. • The crosslinked films had better mechanical property than non-modified films. • Crosslinked collagen–citric acid films could tolerate suture during operation. • The films showed good ability of epithelial and stromal repair

  7. Collagen based film with well epithelial and stromal regeneration as corneal repair materials: Improving mechanical property by crosslinking with citric acid

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xuan; Liu, Yang; Li, Weichang; Long, Kai; Wang, Lin; Liu, Sa; Wang, Yingjun [School of Materials Science and Engineering, South China University of Technology, Guangzhou (China); National Engineering Research Center for Tissue Restoration and Reconstruction, Guangzhou (China); Ren, Li, E-mail: psliren@scut.edu.cn [School of Materials Science and Engineering, South China University of Technology, Guangzhou (China); National Engineering Research Center for Tissue Restoration and Reconstruction, Guangzhou (China)

    2015-10-01

    Corneal disease can lead to vision loss. It has become the second greatest cause of blindness in the world, and keratoplasty is considered as an effective treatment method. This paper presents the crosslinked collagen (Col)–citric acid (CA) films developed by making use of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The results showed that the Col–CA films had necessary optical performance, water content. The collagenase resistance of CA crosslinked films was superior to that of EDC crosslinked films. And CA5 film (Col:CA:EDC:NHS = 60:3:10:10) had the best mechanical properties. Cell experiments showed that CA5 film was non-cytotoxic and human corneal epithelial cells could proliferate well on the films. Lamellar keratoplasty showed that the CA5 film could be sutured in the rabbit eyes and was epithelialized completely in about 10 days, and the transparency was restored quickly in 30 ± 5 days. No inflammation and corneal neovascularization were observed at 6 months. Corneal stroma had been repaired; stromal cells and neo-stroma could be seen in the area of operation from the hematoxylin–eosin stained histologic sections and anterior segment optical coherence tomography images. These results indicated that Col–CA films were highly promising biomaterials that could be used in corneal tissue engineering and a variety of other tissue engineering applications. - Highlights: • Adding different amounts of citric acid could change the properties of films. • The crosslinked films had better mechanical property than non-modified films. • Crosslinked collagen–citric acid films could tolerate suture during operation. • The films showed good ability of epithelial and stromal repair.

  8. Collagenous sprue cross-sectional imaging: a comparative blinded study.

    Science.gov (United States)

    Al-Bawardy, Badr; Sheedy, Shannon P; Herberts, Michelle B; Murray, Joseph A; Rubio-Tapia, Alberto; Rajan, Elizabeth; Bruining, David H; Hansel, Stephanie L; Barlow, John M; Fletcher, Joel G; Fidler, Jeff L

    2017-02-01

    Collagenous sprue (CS) is a rare enteropathy characterized by villous atrophy and a thickened subepithelial collagen band. The aim of this study is to describe the cross-sectional imaging findings of CS. A case-control, retrospective study with cases of all CS patients from January 2000 to 2015 was performed. Inclusion criteria were (1) Histopathologic diagnosis and (2) Imaging with computed tomography abdomen/pelvis (CT A/P), CT enterography (CTE), or magnetic resonance enterography within 6 months of small bowel (SB) biopsy. Control subjects were irritable bowel syndrome (IBS) patients who underwent CTE. Imaging studies were examined by two GI radiologists, blinded to patient data. 108 patients (54 CS; 54 IBS) were included. Mean age was 56.7 ± 16.5 years, and 68% were female (72% in CS group vs. 63% in IBS group; p = 0.3). CS patients were significantly older (67 ± 12 vs. 47 ± 15 year; p reversal (46% vs. 6%; p < 0.001), SB dilation (28% vs. 0%; p < 0.001), SB conformational change (28% vs. 6%; p = 0.002), SB wall thickening (13% vs. 2%; p = 0.03), and ulcerative jejunoileitis (4% vs. 0%; p = 0.01). Radiologists suspected malabsorption in 72% in the CS group and 2% in the IBS group (p < 0.001). Imaging findings suggestive of mucosal malabsorption are commonly demonstrated in CS.

  9. Radiation cross-linked collagen/dextran dermal scaffolds: effects of dextran on cross-linking and degradation.

    Science.gov (United States)

    Zhang, Yaqing; Zhang, Xiangmei; Xu, Ling; Wei, Shicheng; Zhai, Maolin

    2015-01-01

    Ionizing radiation effectively cross-links collagen into network with enhanced anti-degradability and biocompatibility, while radiation-cross-linked collagen scaffold lacks flexibility, satisfactory surface appearance, and performs poor in cell penetration and ingrowth. To make the radiation-cross-linked collagen scaffold to serve as an ideal artificial dermis, dextran was incorporated into collagen. Scaffolds with the collagen/dextran (Col/Dex) ratios of 10/0, 7/3, and 5/5 were fabricated via (60)Co γ-irradiation cross-linking, followed by lyophilization. The morphology, microstructure, physicochemical, and biological properties were investigated. Compared with pure collagen, scaffolds with dextran demonstrated more porous appearance, enhanced hydrophilicity while the cross-linking density was lower with the consequence of larger pore size, higher water uptake, as well as reduced stiffness. Accelerated degradation was observed when dextran was incorporated in both the in vitro and in vivo assays, which led to earlier integration with cell and host tissue. The effect of dextran on degradation was ascribed to the decreased cross-linking density, looser microstructure, more porous and hydrophilic surface. Considering the better appearance, softness, moderate degradation rate due to controllable cross-linking degree and good biocompatibility as well, radiation-cross-linked collagen/dextran scaffolds are expected to serve as promising artificial dermal substitutes.

  10. [The status quo and expectation of corneal research in China].

    Science.gov (United States)

    Shi, Weiyun; Xie, Lixin

    2014-09-01

    In China, corneal disease is currently the second leading cause of blindness. Severe donor shortage, insufficient technique supports and promotion, and the lack of corneal disease specialists due to poor systematic training are all urgent problems to be resolved. The last 5 years have witnessed a considerable progress in basic and clinical researches of corneal disease. Investigations on the pathogenesis and treatment of fungal keratitis have won an international reputation. Results from the study of corneal reconstruction with tissue-engineered and acellular matrix corneas have been tested in clinical trials with good preliminary performance. Moreover, the clinical researches of corneal refractive surgery have kept pace with the latest international progresses. However, Descemet's membrane endothelial keratoplasty needs further promotion, and the development and application of keratoprosthesis remains a blank. Although keratoprosthesis and corneal collagen cross-linking have been widely applied in Europe with satisfactory clinical efficacy, they are still under assessment by China Food and Drug Administration for approval of use.

  11. Impact of corneal cross-linking combined with photorefractive keratectomy on blurring strength

    OpenAIRE

    Labiris, Georgios; Sideroudi, Haris; Angelonias, Dimitris; Georgantzoglou, Kimonas; Kozobolis, Vassilios P

    2016-01-01

    Georgios Labiris,1,2 Haris Sideroudi,2 Dimitris Angelonias,2 Kimonas Georgantzoglou,2 Vassilios P Kozobolis1,21Department of Ophthalmology, University Hospital of Alexandroupolis, 2Eye Institute of Thrace, Alexandroupolis, GreecePurpose: The aim of this study was to evaluate the impact of corneal cross-linking combined with photorefractive keratectomy (PRK) on blurring strength.Methods: A total of 63 patients with keratoconus were recruited for this study, and two study groups were formed acc...

  12. Efficacy of iontophoresis-assisted epithelium-on corneal cross-linking for keratoconus

    Directory of Open Access Journals (Sweden)

    Hong-Zhen Jia

    2018-04-01

    Full Text Available Corneal cross-linking (CXL is a noninvasive therapeutic procedure for keratoconus that is aimed at improving corneal biomechanical properties by induction of covalent cross-links between stromal proteins. It is accomplished by ultraviolet A (UVA radiation of the cornea, which is first saturated with photosensitizing riboflavin. It has been shown that standard epithelium-off CXL (S-CXL is efficacious, and it has been recommended as the standard of care procedure for keratoconus. However, epithelial removal leads to pain, transient vision loss, and a higher risk of corneal infection. To avoid these disadvantages, transepithelial CXL was developed. Recently, iontophoresis has been adopted to increase riboflavin penetration through the epithelium. Several clinical observations have demonstrated the safety and efficacy of iontophoresis-assisted epithelium-on CXL (I-CXL for keratoconus. This review aimed to provide a comprehensive summary of the published studies regarding I-CXL and a comparison between I-CXL and S-CXL. All articles used in this review were mainly retrieved from the PubMed database. Original articles and reviews were selected if they were related to the I-CXL technique or related to the comparison between I-CXL and S-CXL.

  13. Distribution of Young's modulus in porcine corneas after riboflavin/UVA-induced collagen cross-linking as measured by atomic force microscopy.

    Directory of Open Access Journals (Sweden)

    Jan Seifert

    Full Text Available Riboflavin/UVA-induced corneal collagen cross-linking has become an effective clinical application to treat keratoconus and other ectatic disorders of the cornea. Its beneficial effects are attributed to a marked stiffening of the unphysiologically weak stroma. Previous studies located the stiffening effect predominantly within the anterior cornea. In this study, we present an atomic force microscopy-derived analysis of the depth-dependent distribution of the Young's modulus with a depth resolution of 5 µm in 8 cross-linked porcine corneas and 8 contralateral controls. Sagittal cryosections were fabricated from every specimen and subjected to force mapping. The mean stromal depth of the zone with effective cross-linking was found to be 219 ± 67 µm. Within this cross-linked zone, the mean Young's modulus declined from 49 ± 18 kPa at the corneal surface to 46 ± 17 kPa, 33 ± 11 kPa, 17 ± 5 kPa, 10 ± 4 kPa and 10 ± 4 kPa at stromal depth intervals of 0-50 µm, 50-100 µm, 100-150 µm, 150-200 µm and 200-250 µm, respectively. This corresponded to a stiffening by a factor of 8.1 (corneal surface, 7.6 (0-50 µm, 5.4 (50-100 µm, 3.0 (100-150 µm, 1.6 (150-200 µm, and 1.5 (200-250 µm, when compared to the Young's modulus of the posterior 100 µm. The mean Young's modulus within the cross-linked zone was 20 ± 8 kPa (2.9-fold stiffening, while it was 11 ± 4 kPa (1.7-fold stiffening for the entire stroma. Both values were significantly distinct from the mean Young's modulus obtained from the posterior 100 µm of the cross-linked corneas and from the contralateral controls. In conclusion, we were able to specify the depth-dependent distribution of the stiffening effect elicited by standard collagen cross-linking in porcine corneas. Apart from determining the depth of the zone with effective corneal cross-linking, we also developed a method that allows for atomic force microscopy-based measurements of gradients of Young's modulus in soft

  14. Laser-induced corneal cross-linking upon photorefractive ablation with riboflavin

    Directory of Open Access Journals (Sweden)

    Kornilovskiy IM

    2016-04-01

    Full Text Available Igor M Kornilovskiy,1 Elmar M Kasimov,2 Ayten I Sultanova,2 Alexander A Burtsev1 1Department of Eye Diseases, Federal State Budgetary Institution “National Pirogov Medical Surgical Centre”, Ministry of Health, Moscow, Russia; 2Department of Eye Diseases, Zarifa Aliyeva National Ophthalmology Center, Ministry of Health, Baku, Azerbaijan Aim: To estimate the biomechanical effect of the laser-induced cross-linking resulting from photorefractive ablation of the cornea with riboflavin.Methods: Excimer laser ablation studies were performed ex vivo (32 eyes of 16 rabbits by phototherapeutic keratectomy (PTK and in vivo (24 eyes of 12 rabbits by transepithelial photorefractive keratectomy (TransPRK, with and without riboflavin saturation of the stroma. Then, we performed corneal optical coherence tomography on 36 eyes of 18 patients with varying degrees of myopia at different times after the TransPRK was performed with riboflavin saturation of the stroma.Results: Biomechanical testing of corneal samples saturated with riboflavin revealed cross-linking effect accompanied by the increase in tensile strength and maximum strength. PTK showed increase in tensile strength from 5.1±1.4 to 7.2±1.6 MPa (P=0.001, while TransPRK showed increase in tensile strength from 8.8±0.9 to 12.8±1.3 MPa (P=0.0004. Maximum strength increased from 8.7±2.5 to 12.0±2.8 N (P=0.005 in PTK and from 12.8±1.6 to 18.3±1.2 N (P=0.0004 in TransPRK. Clinical optical coherence tomography studies of the biomicroscopic transparent cornea at different times after TransPRK showed increased density in the surface layers of the stroma and membrane-like structure beneath the epithelium.Conclusion: Photorefractive ablation of the preliminary corneal stroma saturation with riboflavin causes the effect of laser-induced cross-linking, which is attended with an increase in corneal tensile strength, maximum strength, increased density in the surface layers of the stroma, and formation of

  15. Evaluation of epigallocatechin-3-gallate (EGCG) cross-linked collagen membranes and concerns on osteoblasts

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Chenyu; Deng, Jia [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Xiang, Lin; Wu, Yingying [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Oral Implantology, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Wei, Xiawei [State Key Laboratory of Biotherapy and Laboratory for Aging Research, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 (China); Qu, Yili [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Oral Implantology, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Man, Yi, E-mail: manyi780203@126.com [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Oral Implantology, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China)

    2016-10-01

    Collagen membranes have ideal biological and mechanical properties for supporting infiltration and proliferation of osteoblasts and play a vital role in guided bone regeneration (GBR). However, pure collagen can lead to inflammation, resulting in progressive bone resorption. Therefore, a method for regulating the level of inflammatory cytokines at surgical sites is paramount for the healing process. Epigallocatechin-3-gallate (EGCG) is a component extracted from green tea with numerous biological activities including an anti-inflammatory effect. Herein, we present a novel cross-linked collagen membrane containing different concentrations of EGCG (0.0064%, 0.064%, and 0.64%) to regulate the level of inflammatory factors secreted by pre-osteoblast cells; improve cell proliferation; and increase the tensile strength, wettability, and thermal stability of collagen membranes. Scanning electron microscope images show that the surfaces of collagen membranes became smoother and the collagen fiber diameters became larger with EGCG treatment. Measurement of the water contact angle demonstrated that introducing EGCG improved membrane wettability. Fourier transform infrared spectroscopy analyses indicated that the backbone of collagen was intact, and the thermal stability was significant improved in differential scanning calorimetry. The mechanical properties of 0.064% and 0.64% EGCG-treated collagen membranes were 1.5-fold greater than those of the control. The extent of cross-linking was significantly increased, as determined by a 2,4,6-trinitrobenzenesulfonic acid solution assay. The Cell Counting Kit-8 (CCK-8) and live/dead assays revealed that collagen membrane cross-linked by 0.0064% EGCG induced greater cell proliferation than pure collagen membranes. Additionally, real-time polymerase chain reaction and enzyme-linked immunosorbent assay results showed that EGCG significantly affected the production of inflammatory factors secreted by MC3T3-E1 cells. Taken together, our

  16. Long-term safety and efficacy follow-up of prophylactic higher fluence collagen cross-linking in high myopic laser-assisted in situ keratomileusis

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2012-07-01

    Full Text Available Anastasios John KanellopoulosLaservision.gr Institute, Athens, Greece, and New York University Medical School, New York, NY, USABackground: The purpose of this study was to evaluate the safety and efficacy of ultraviolet A irradiation cross-linking on completion for cases of high myopic laser-assisted in situ keratomileusis (LASIK.Methods: Forty-three consecutive LASIK cases treated with femtosecond laser flap and the WaveLight excimer platform were evaluated perioperatively for uncorrected visual acuity, best corrected spectacle visual acuity, refraction, keratometry, topography, total and flap pachymetry, corneal optical coherence tomography, and endothelial cell count. All eyes at the completion of LASIK had cross-linking through the repositioned flap, with higher fluence (10 mW/cm2 ultraviolet light of an average 370 µm wavelength and 10 mW/cm2 fluence applied for 3 minutes following an earlier single instillation of 0.1% riboflavin within the flap interface. Mean follow-up duration was 3.5 (range 1.0–4.5 years.Results: Mean uncorrected visual acuity changed from 0.2 to 1.2, best corrected spectacle visual acuity from 1.1 to 1.2, spherical equivalent from -7.5 diopters (D to -0.2 D, keratometry from 44.5 D to 38 D, flap pachymetry from 105 µm to, total pachymetry from 525 to 405, and endothelial cell count from 2750 to 2800. None of the cases developed signs of ectasia or significant regression during follow-up.Conclusion: Prophylactic collagen cross-linking for high-risk LASIK cases appears to be a safe and effective adjunctive treatment for refractive regression and potential ectasia. This application may be viewed as prophylactic customization of the biomechanical behavior of corneal collagen.Keywords: prophylactic collagen cross-linking, laser-assisted in situ keratomileusis, high-risk, post-LASIK ectasia

  17. Cross-linking of dermal sheep collagen using a water-soluble carbodiimide

    NARCIS (Netherlands)

    Damink, LHHO; Dijkstra, PJ; vanLuyn, MJA; vanWachem, PB; Nieuwenhuis, P; Feijen, J

    A cross-linking method for collagen-based biomaterials was developed using the water-soluble carbodiimide 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide hydrochloride (EDC). Cross-linking using EDC involves the activation of carboxylic acid groups to give O-acylisourea groups, which form cross-links

  18. Cross-linking of dermal sheep collagen using a water-soluble carbodiimide

    NARCIS (Netherlands)

    Olde damink, L.H.H.; Olde Damink, L.H.H.; Dijkstra, Pieter J.; van Luyn, M.J.A.; van Wachem, P.B.; Nieuwenhuis, P.; Feijen, Jan

    1996-01-01

    A cross-linking method for collagen-based biomaterials was developed using the water-soluble carbodiimide 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide hydrochloride (EDC). Cross-linking using EDC involves the activation of carboxylic acid groups to give O-acylisourea groups, which form cross-links

  19. Collagen cross-linking: insights on the evolution of metazoan extracellular matrix.

    Science.gov (United States)

    Rodriguez-Pascual, Fernando; Slatter, David Anthony

    2016-11-23

    Collagens constitute a large family of extracellular matrix (ECM) proteins that play a fundamental role in supporting the structure of various tissues in multicellular animals. The mechanical strength of fibrillar collagens is highly dependent on the formation of covalent cross-links between individual fibrils, a process initiated by the enzymatic action of members of the lysyl oxidase (LOX) family. Fibrillar collagens are present in a wide variety of animals, therefore often being associated with metazoan evolution, where the emergence of an ancestral collagen chain has been proposed to lead to the formation of different clades. While LOX-generated collagen cross-linking metabolites have been detected in different metazoan families, there is limited information about when and how collagen acquired this particular modification. By analyzing telopeptide and helical sequences, we identified highly conserved, potential cross-linking sites throughout the metazoan tree of life. Based on this analysis, we propose that they have importantly contributed to the formation and further expansion of fibrillar collagens.

  20. Cross-linking in collagen by nonenzymatic glycation increases the matrix stiffness in rabbit achilles tendon.

    Science.gov (United States)

    Reddy, G Kesava

    2004-01-01

    Nonenzymatic glycation of connective tissue matrix proteins is a major contributor to the pathology of diabetes and aging. Previously the author and colleagues have shown that nonenzymatic glycation significantly enhances the matrix stability in the Achilles tendon (Reddy et al., 2002, Arch. Biochem. Biophys., 399, 174-180). The present study was designed to gain further insight into glycation-induced collagen cross-linking and its relationship to matrix stiffness in the rabbit Achilles tendon. The glycation process was initiated by incubating the Achilles tendons (n = 6) in phosphate-buffered saline containing ribose, whereas control tendons (n = 6) were incubated in phosphate-buffered saline without ribose. Eight weeks following glycation, the biomechanical attributes as well as the degree of collagen cross-linking were determined to examine the potential associations between matrix stiffness and molecular properties of collagen. Compared to nonglycated tendons, the glycated tendons showed increased maximum load, stress, strain, Young's modulus of elasticity, and toughness indicating that glycation increases the matrix stiffness in the tendons. Glycation of tendons resulted in a considerable decrease in soluble collagen content and a significant increase in insoluble collagen and pentosidine. Analysis of potential associations between the matrix stiffness and degree of collagen cross-linking showed that both insoluble collagen and pentosidine exhibited a significant positive correlation with the maximum load, stress, and strain, Young's modulus of elasticity, and toughness (r values ranging from.61 to.94) in the Achilles tendons. However, the soluble collagen content present in neutral salt buffer, acetate buffer, and acetate buffer containing pepsin showed an inverse relation with the various biomechanical attributes tested (r values ranging from.22 to.84) in the Achilles tendons. The results of the study demonstrate that glycation-induced collagen cross

  1. Collagen and elastin cross-linking is altered during aberrant late lung development associated with hyperoxia.

    Science.gov (United States)

    Mižíková, Ivana; Ruiz-Camp, Jordi; Steenbock, Heiko; Madurga, Alicia; Vadász, István; Herold, Susanne; Mayer, Konstantin; Seeger, Werner; Brinckmann, Jürgen; Morty, Rory E

    2015-06-01

    Maturation of the lung extracellular matrix (ECM) plays an important role in the formation of alveolar gas exchange units. A key step in ECM maturation is cross-linking of collagen and elastin, which imparts stability and functionality to the ECM. During aberrant late lung development in bronchopulmonary dysplasia (BPD) patients and animal models of BPD, alveolarization is blocked, and the function of ECM cross-linking enzymes is deregulated, suggesting that perturbed ECM cross-linking may impact alveolarization. In a hyperoxia (85% O2)-based mouse model of BPD, blunted alveolarization was accompanied by alterations to lung collagen and elastin levels and cross-linking. Total collagen levels were increased (by 63%). The abundance of dihydroxylysinonorleucine collagen cross-links and the dihydroxylysinonorleucine-to-hydroxylysinonorleucine ratio were increased by 11 and 18%, respectively, suggestive of a profibrotic state. In contrast, insoluble elastin levels and the abundance of the elastin cross-links desmosine and isodesmosine in insoluble elastin were decreased by 35, 30, and 21%, respectively. The lung collagen-to-elastin ratio was threefold increased. Treatment of hyperoxia-exposed newborn mice with the lysyl oxidase inhibitor β-aminopropionitrile partially restored normal collagen levels, normalized the dihydroxylysinonorleucine-to-hydroxylysinonorleucine ratio, partially normalized desmosine and isodesmosine cross-links in insoluble elastin, and partially restored elastin foci structure in the developing septa. However, β-aminopropionitrile administration concomitant with hyperoxia exposure did not improve alveolarization, evident from unchanged alveolar surface area and alveoli number, and worsened septal thickening (increased by 12%). These data demonstrate that collagen and elastin cross-linking are perturbed during the arrested alveolarization of developing mouse lungs exposed to hyperoxia. Copyright © 2015 the American Physiological Society.

  2. Cross-linking of collagen-based materials

    NARCIS (Netherlands)

    Zeeman, R.

    1998-01-01

    An example of a collagen-based tissue is the aortic heart valve. A variety of pathological processes can lead to heart valve malfunction and this is usually associated with degenerative changes of the tissue. The most commonly used types of prosthetic valves are mechanical and tissue valves. One

  3. MICROWAVE IRRADIATION AND CROSS-LINKING OF COLLAGEN

    NARCIS (Netherlands)

    VISSER, CE; VOUTE, ABE; OOSTING, J; BOON, ME; KOK, LP

    1992-01-01

    In a multifactorial experiment, dermal sheep collagen was treated in diluted glutaraldehyde solutions, 70% ethyl alcohol, Cialit 1:5000, and distilled water for 1, 3 and 5 min, respectively, in combination with microwave irradiation at different temperature settings. The shrinkage temperature

  4. SECONDARY CYTOTOXICITY OF CROSS-LINKED DERMAL SHEEP COLLAGENS DURING REPEATED EXPOSURE TO HUMAN FIBROBLASTS

    NARCIS (Netherlands)

    VANLUYN, MJA; VANWACHEM, PB; DAMINK, LHHO; DIJKSTRA, PJ; FEIJEN, J; NIEUWENHUIS, P

    1992-01-01

    We investigated commercially available dermal sheep collagen either cross-linked with hexamethylenedlisocyanate, or cross-linked with glutaraldehyde. In previous in vitro studies we could discriminate primary, i.e. extractable, and secondary cytotoxicity, due to cell-biomaterial interactions, i.e.

  5. Stabilization of collagen nanofibers with l-lysine improves the ability of carbodiimide cross-linked amniotic membranes to preserve limbal epithelial progenitor cells

    Directory of Open Access Journals (Sweden)

    Lai JY

    2014-11-01

    provide a useful strategy to assist in the development of carbodiimide cross-linked amniotic membrane as a stable stem cell niche for corneal epithelial tissue engineering.Keywords: amniotic membrane, L-lysine-pretreated concentration, collagen nanofiber stabilization, limbal progenitor cell preservation, corneal epithelial tissue engineering

  6. Collagen cross-linking in sun-exposed and unexposed sites of aged human skin

    Science.gov (United States)

    Yamauchi, M.; Prisayanh, P.; Haque, Z.; Woodley, D. T.

    1991-01-01

    A recently described nonreducible, acid-heat stable compound, histidinohydroxylysinonorleucine (HHL), is a collagen cross-link isolated from mature skin tissue. Its abundance is related to chronologic aging of skin. The present communication describes the quantity of HHL from aged human skin of the same individuals in sun-exposed (wrist) and unexposed (buttock) sites. Punch biopsies were obtained from these sites from nine people of age 60 or older. HHL contents (moles/mole of collagen) at these sites were for wrist 0.13 +/- 0.07 and for buttock 0.69 +/- 0.17 (mean +/- SD, p less than 0.001). In addition, it was found that acute irradiation of the cross-linked peptides with UVA (up to 250 J/cm2) and UVB (up to 1 J/cm2) had no effect on HHL structure. The same treatment significantly degraded another nonreducible, stable collagen cross-link, pyridinoline. The results suggest that chronic sunlight exposure may be associated with an impediment to normal maturation of human dermal collagen resulting in tenuous amount of HHL. Thus, the process of photoaging in dermal collagen is different from that of chronologic aging in human skin.

  7. Mechanical properties and collagen cross-linking of the patellar tendon in old and young men

    DEFF Research Database (Denmark)

    Couppé, C; Hansen, P; Kongsgaard, M

    2009-01-01

    were higher in OM than in YM (73 +/- 13 vs. 11 +/- 2 mmol/mol; P appreciably influence the dimensions or mechanical properties of the human patellar tendon in vivo. Collagen concentration was reduced, whereas both enzymatic......Age-related loss in muscle mass and strength impairs daily life function in the elderly. However, it remains unknown whether tendon properties also deteriorate with age. Cross-linking of collagen molecules provides structural integrity to the tendon fibrils and has been shown to change with age...... in animals but has never been examined in humans in vivo. In this study, we examined the mechanical properties and pyridinoline and pentosidine cross-link and collagen concentrations of the patellar tendon in vivo in old (OM) and young men (YM). Seven OM (67 +/- 3 years, 86 +/- 10 kg) and 10 YM (27 +/- 2...

  8. Stromal demarcation line induced by corneal cross-linking in eyes with keratoconus and nonkeratoconic asymmetric topography.

    Science.gov (United States)

    Malta, João B N; Renesto, Adimara C; Moscovici, Bernardo K; Soong, H K; Campos, Mauro

    2015-02-01

    To evaluate stromal demarcation lines following corneal cross-linking (CXL) using anterior segment optical coherence tomography in patients with keratoconus and nonkeratoconic asymmetric topography. Fifth-nine eyes of 59 patients were enrolled in a retrospective comparative case series, of which 19 eyes had keratoconus and 40 eyes had asymmetric topography. Eyes with asymmetric topography were treated in preparation for photorefractive keratectomy. One month after CXL, a stromal demarcation line was evaluated at 5 standardized corneal points using anterior segment optical coherence tomography. Mean stromal demarcation line depths were measured at 5 points on the cornea, namely, centrally, 3.0 mm temporally, 1.5 mm temporally, 3.0 mm nasally, and 1.5 mm nasally. For the keratoconus group, the values were 178 ± 47, 123 ± 15, 152 ± 47, 125 ± 23, and 160 ± 43 μm, respectively. For the asymmetric corneal topography group (without keratoconus), they were 305 ± 64, 235 ± 57, 294 ± 50, 214 ± 54, and 285 ± 58 μm, respectively. There was no correlation between central corneal pachymetry and stromal demarcation line depth in all 5 measured corneal points in both groups. CXL treatment profiles are similar in keratoconic and nonkeratoconic eyes with asymmetric topography.

  9. In vitro degradation of dermal sheep collagen cross-linked using a water-soluble carbodiimide

    NARCIS (Netherlands)

    Damink, LHHO; Dijkstra, PJ; vanLuyn, MJA; vanWachem, PB; Nieuwenhuis, P; Feijen, J

    Bacterial collagenase was used to study the susceptibility of dermal sheep collagen (DSC) cross-inked with a mixture of the water-soluble carbodiimide 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide (EIN-DSC) towards enzymatic degradation. Contrary to

  10. The mechanism of collagen cross-linking in diabetes: a puzzle nearing resolution.

    Science.gov (United States)

    Monnier, V M; Glomb, M; Elgawish, A; Sell, D R

    1996-07-01

    Considerable interest has been focused in recent years on the mechanism of collagen cross-linking by high glucose in vitro and in vivo. Experiments in both diabetic humans and in animals have shown that over time collagen becomes less soluble, less digestible by collagenase, more stable to heat-induced denaturation, and more glycated. In addition, collagen becomes more modified by advanced products of the Maillard reaction, i.e., immunoreactive advanced glycation end products and the glycoxidation markers carboxymethyllysine and pentosidine. Mechanistic studies have shown that collagen cross-linking in vitro can be uncoupled from glycation by the use of antioxidants and chelating agents. Experiments in the authors' laboratory revealed that approximately 50% of carboxymethyllysine formed in vitro originates from pathways other than oxidation of Amadori products, i.e., most likely the oxidation of Schiff base-linked glucose. In addition, the increase in thermal stability of rat tail tendons exposed to high glucose in vitro or in vivo was found to strongly depend on H2O2 formation. The final missing piece of the puzzle is that of the structure of the major cross-link. We speculate that it is a nonfluorescent nonultraviolet active cross-link between two lysine residues, which includes a fragmentation product of glucose linked in a nonreducible bond labile to both strong acids and bases.

  11. Late onset of a persistent, deep stromal scarring after PRK and corneal cross-linking in a patient with forme fruste keratoconus.

    Science.gov (United States)

    Güell, Jose L; Verdaguer, Paula; Elies, Daniel; Gris, Oscar; Manero, Felicidad

    2014-04-01

    To present a case of a late, deep stromal scar in a 22-year-old patient with forme fruste keratoconus who underwent combined corneal cross-linking and photorefractive keratectomy (PRK). Topography-guided corneal cross-linking combined with corneal PRK (without complications) was performed in both eyes with a delay of 2 weeks between each eye. At the 5-month postoperative examination of the right eye, a localized corneal haze was circumscribed to the posterior deep stroma, signifying a decrease of visual acuity. However, this improved partially and temporarily when treated with topical corticoids during 2 years of follow-up and then reoccurred, affecting the corrected distance visual acuity. To the authors' knowledge, this is the first documented, clinical case presenting a deep stromal affectation without endothelial decompensation and visual acuity affectation as a postoperative complication following topography-guided PRK and corneal cross-linking. Copyright 2014, SLACK Incorporated.

  12. Cyclophilin-B Modulates Collagen Cross-linking by Differentially Affecting Lysine Hydroxylation in the Helical and Telopeptidyl Domains of Tendon Type I Collagen.

    Science.gov (United States)

    Terajima, Masahiko; Taga, Yuki; Chen, Yulong; Cabral, Wayne A; Hou-Fu, Guo; Srisawasdi, Sirivimol; Nagasawa, Masako; Sumida, Noriko; Hattori, Shunji; Kurie, Jonathan M; Marini, Joan C; Yamauchi, Mitsuo

    2016-04-29

    Covalent intermolecular cross-linking provides collagen fibrils with stability. The cross-linking chemistry is tissue-specific and determined primarily by the state of lysine hydroxylation at specific sites. A recent study on cyclophilin B (CypB) null mice, a model of recessive osteogenesis imperfecta, demonstrated that lysine hydroxylation at the helical cross-linking site of bone type I collagen was diminished in these animals (Cabral, W. A., Perdivara, I., Weis, M., Terajima, M., Blissett, A. R., Chang, W., Perosky, J. E., Makareeva, E. N., Mertz, E. L., Leikin, S., Tomer, K. B., Kozloff, K. M., Eyre, D. R., Yamauchi, M., and Marini, J. C. (2014) PLoS Genet 10, e1004465). However, the extent of decrease appears to be tissue- and molecular site-specific, the mechanism of which is unknown. Here we report that although CypB deficiency resulted in lower lysine hydroxylation in the helical cross-linking sites, it was increased in the telopeptide cross-linking sites in tendon type I collagen. This resulted in a decrease in the lysine aldehyde-derived cross-links but generation of hydroxylysine aldehyde-derived cross-links. The latter were absent from the wild type and heterozygous mice. Glycosylation of hydroxylysine residues was moderately increased in the CypB null tendon. We found that CypB interacted with all lysyl hydroxylase isoforms (isoforms 1-3) and a putative lysyl hydroxylase-2 chaperone, 65-kDa FK506-binding protein. Tendon collagen in CypB null mice showed severe size and organizational abnormalities. The data indicate that CypB modulates collagen cross-linking by differentially affecting lysine hydroxylation in a site-specific manner, possibly via its interaction with lysyl hydroxylases and associated molecules. This study underscores the critical importance of collagen post-translational modifications in connective tissue formation. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. Cyclophilin-B Modulates Collagen Cross-linking by Differentially Affecting Lysine Hydroxylation in the Helical and Telopeptidyl Domains of Tendon Type I Collagen*

    Science.gov (United States)

    Terajima, Masahiko; Taga, Yuki; Chen, Yulong; Cabral, Wayne A.; Hou-Fu, Guo; Srisawasdi, Sirivimol; Nagasawa, Masako; Sumida, Noriko; Hattori, Shunji; Kurie, Jonathan M.; Marini, Joan C.; Yamauchi, Mitsuo

    2016-01-01

    Covalent intermolecular cross-linking provides collagen fibrils with stability. The cross-linking chemistry is tissue-specific and determined primarily by the state of lysine hydroxylation at specific sites. A recent study on cyclophilin B (CypB) null mice, a model of recessive osteogenesis imperfecta, demonstrated that lysine hydroxylation at the helical cross-linking site of bone type I collagen was diminished in these animals (Cabral, W. A., Perdivara, I., Weis, M., Terajima, M., Blissett, A. R., Chang, W., Perosky, J. E., Makareeva, E. N., Mertz, E. L., Leikin, S., Tomer, K. B., Kozloff, K. M., Eyre, D. R., Yamauchi, M., and Marini, J. C. (2014) PLoS Genet. 10, e1004465). However, the extent of decrease appears to be tissue- and molecular site-specific, the mechanism of which is unknown. Here we report that although CypB deficiency resulted in lower lysine hydroxylation in the helical cross-linking sites, it was increased in the telopeptide cross-linking sites in tendon type I collagen. This resulted in a decrease in the lysine aldehyde-derived cross-links but generation of hydroxylysine aldehyde-derived cross-links. The latter were absent from the wild type and heterozygous mice. Glycosylation of hydroxylysine residues was moderately increased in the CypB null tendon. We found that CypB interacted with all lysyl hydroxylase isoforms (isoforms 1–3) and a putative lysyl hydroxylase-2 chaperone, 65-kDa FK506-binding protein. Tendon collagen in CypB null mice showed severe size and organizational abnormalities. The data indicate that CypB modulates collagen cross-linking by differentially affecting lysine hydroxylation in a site-specific manner, possibly via its interaction with lysyl hydroxylases and associated molecules. This study underscores the critical importance of collagen post-translational modifications in connective tissue formation. PMID:26934917

  14. Absence of FKBP10 in recessive type XI osteogenesis imperfecta leads to diminished collagen cross-linking and reduced collagen deposition in extracellular matrix.

    Science.gov (United States)

    Barnes, Aileen M; Cabral, Wayne A; Weis, MaryAnn; Makareeva, Elena; Mertz, Edward L; Leikin, Sergey; Eyre, David; Trujillo, Carlos; Marini, Joan C

    2012-11-01

    Recessive osteogenesis imperfecta (OI) is caused by defects in genes whose products interact with type I collagen for modification and/or folding. We identified a Palestinian pedigree with moderate and lethal forms of recessive OI caused by mutations in FKBP10 or PPIB, which encode endoplasmic reticulum resident chaperone/isomerases FKBP65 and CyPB, respectively. In one pedigree branch, both parents carry a deletion in PPIB (c.563_566delACAG), causing lethal type IX OI in their two children. In another branch, a child with moderate type XI OI has a homozygous FKBP10 mutation (c.1271_1272delCCinsA). Proband FKBP10 transcripts are 4% of control and FKBP65 protein is absent from proband cells. Proband collagen electrophoresis reveals slight band broadening, compatible with ≈10% over-modification. Normal chain incorporation, helix folding, and collagen T(m) support a minimal general collagen chaperone role for FKBP65. However, there is a dramatic decrease in collagen deposited in culture despite normal collagen secretion. Mass spectrometry reveals absence of hydroxylation of the collagen telopeptide lysine involved in cross-linking, suggesting that FKBP65 is required for lysyl hydroxylase activity or access to type I collagen telopeptide lysines, perhaps through its function as a peptidylprolyl isomerase. Proband collagen to organics ratio in matrix is approximately 30% of normal in Raman spectra. Immunofluorescence shows sparse, disorganized collagen fibrils in proband matrix. Published 2012 Wiley Periodicals, Inc.*This article is a US Government work and, as such, is in the public domain of the United States of America.

  15. Corneal Laceration

    Medline Plus

    Full Text Available ... Ophthalmology/Strabismus Ocular Pathology/Oncology Oculoplastics/Orbit Refractive ... Corneal Laceration Sections What Is Corneal Laceration? Corneal Laceration Symptoms What Causes ...

  16. Two-photon induced collagen cross-linking in bioartificial cardiac tissue

    Science.gov (United States)

    Kuetemeyer, Kai; Kensah, George; Heidrich, Marko; Meyer, Heiko; Martin, Ulrich; Gruh, Ina; Heisterkamp, Alexander

    2011-08-01

    Cardiac tissue engineering is a promising strategy for regenerative therapies to overcome the shortage of donor organs for transplantation. Besides contractile function, the stiffness of tissue engineered constructs is crucial to generate transplantable tissue surrogates with sufficient mechanical stability to withstand the high pressure present in the heart. Although several collagen cross-linking techniques have proven to be efficient in stabilizing biomaterials, they cannot be applied to cardiac tissue engineering, as cell death occurs in the treated area. Here, we present a novel method using femtosecond (fs) laser pulses to increase the stiffness of collagen-based tissue constructs without impairing cell viability. Raster scanning of the fs laser beam over riboflavin-treated tissue induced collagen cross-linking by two-photon photosensitized singlet oxygen production. One day post-irradiation, stress-strain measurements revealed increased tissue stiffness by around 40% being dependent on the fibroblast content in the tissue. At the same time, cells remained viable and fully functional as demonstrated by fluorescence imaging of cardiomyocyte mitochondrial activity and preservation of active contraction force. Our results indicate that two-photon induced collagen cross-linking has great potential for studying and improving artificially engineered tissue for regenerative therapies.

  17. Effect of nordihydroguaiaretic acid cross-linking on fibrillar collagen: in vitro evaluation of fibroblast adhesion strength and migration

    Directory of Open Access Journals (Sweden)

    Ana Y. Rioja

    2017-04-01

    Full Text Available Fixation is required to reinforce reconstituted collagen for orthopedic bioprostheses such as tendon or ligament replacements. Previous studies have demonstrated that collagen fibers cross-linked by the biocompatible dicatechol nordihydroguaiaretic acid (NDGA have mechanical strength comparable to native tendons. This work focuses on investigating fibroblast behavior on fibrillar and NDGA cross-linked type I collagen to determine if NDGA modulates cell adhesion, morphology, and migration. A spinning disk device that applies a range of hydrodynamic forces under uniform chemical conditions was employed to sensitively quantify cell adhesion strength, and a radial barrier removal assay was used to measure cell migration on films suitable for these quantitative in vitro assays. The compaction of collagen films, mediated by the drying and cross-linking fabrication process, suggests a less open organization compared to native fibrillar collagen that likely allowed the collagen to form more inter-chain bonds and chemical links with NDGA polymers. Fibroblasts strongly adhered to and migrated on native and NDGA cross-linked fibrillar collagen; however, NDGA modestly reduced cell spreading, adhesion strength and migration rate. Thus, it is hypothesized that NDGA cross-linking masked some adhesion receptor binding sites either physically, chemically, or both, thereby modulating adhesion and migration. This alteration in the cell-material interface is considered a minimal trade-off for the superior mechanical and compatibility properties of NDGA cross-linked collagen compared to other fixation approaches.

  18. Can possible toxic effect of ultraviolet-A after corneal cross-linking be prevented? In vitro transmittance study of contact lenses at 370 nm wavelength.

    Science.gov (United States)

    Bilgihan, Kamil; Yuksel, Erdem; Deniz, Nuriye Gokcen; Yuksel, Nilay

    2015-01-01

    Corneal collagen cross linking (CCL) with ultraviolet A (UVA) has been proposed as a treatment for the progression of corneal ectasia associated with keratoconus and post-laser-assisted in situ keratomileusis (LASIK) ectasia. Despite the reports about safety of procedure, we consider that UVA of sunlight can effect riboflavin saturated and de-epitelizated cornea early after CCL. To evaluate the UVA blockage capability of 11 different silicone hydrogel contact lenses which are widely used after CCL treatment. Eleven different silicone hydrogel and daily disposable contact lenses were evaluated. The UVA light at 365 nm wavelength for UVA source and UV light meter to measure UVA radiation were used. 3, 9 and 18 mW/cm(2) power of UV radiance was applied centrally to the each type of contact lenses. The power of UVA transmittance for each radiance and percentage of blockage were evaluated for each brand. Also, protection factor (PF) was calculated. The senofilcon A and narafilcon A had the highest blockage and lowest transmittance (p = 0.02). PF was significantly higher in the senofilcon A and narafilcon A at 3, 9 and 18 mW/cm(2) (p = 0.0001). And also, the hilafilcon B, filcon IV, nelfilcon A, enfilcon A, lotrafilcon A and lotrafilcon B had the highest UVA transmittance. The narafilcon A and the senofilcon A may be a good options for epithelial healing after CCL procedure to protect the cornea from UVA of sunlight. And also, the hilafilcon B, filcon IV, nelfilcon A, enfilcon A, lotrafilcon A and lotrafilcon B contact lenses that have high-UVA transmittance feature can be a treatment choice for contact lens-assisted CCL technique in thin corneas.

  19. Automated Detection and Classification of Corneal Haze Using Optical Coherence Tomography in Patients With Keratoconus After Cross-Linking.

    Science.gov (United States)

    Dhaini, Ahmad R; Abdul Fattah, Maamoun; El-Oud, Sara Maria; Awwad, Shady T

    2018-03-13

    To evaluate a proposed technology for offering objective grading and mapping of corneal haze as detected by corneal spectral domain optical coherence tomography after corneal cross-linking. This was a retrospective study to evaluate corneal optical coherence tomography images performed on 44 eyes of 44 patients who underwent corneal cross-linking between January 2014 and May 2015, at the American University of Beirut Medical Center. Overall average brightness of the cornea was markedly increased from 43.4% (±6.0) at baseline to 50.2% (±4.4) at 1 month, 47.9% (±4.4) at 3 months, and 46.4% (±5.7) at 6 months with P <0.001, <0.001, and 0.005, respectively. In the anterior stroma, the average brightness significantly increased at 1, 3, and 6 months with values of 54.8% (±3.9), 52.5% (±5.2), and 49.7% (±6.9) with P <0.001, <0.001, and 0.003, respectively. In the mid stroma, the change was clinically significant at 1 and 3 months, whereas in the posterior stroma, it was only significant at 1 month compared with baseline (P = 0.003). Overall, haze was mostly present at 1 month after surgery in all regions, especially in the anterior (32.1%; ±19.2) and mid stromal regions (9.1%; ±18.8), P <0.001 and 0.001, respectively. In contrast, haze in the posterior stromal region peaks at 3 and 6 months after surgery. Anterior stromal haze was the greatest in intensity and area and it was present for a longer time span than mid and posterior stromal haze. At 12 months, the anterior stroma had still more haze intensity than preoperatively. This image-based software can provide objective and valuable quantitative measurements of corneal haze, which may impact clinical decision-making after different corneal surgeries.

  20. Cross-Linking in Collagen by Nonenzymatic Glycation Increases the Matrix Stiffness in Rabbit Achilles Tendon

    OpenAIRE

    Reddy, G. Kesava

    2004-01-01

    Nonenzymatic glycation of connective tissue matrix proteins is a major contributor to the pathology of diabetes and aging. Previously the author and colleagues have shown that nonenzymatic glycation significantly enhances the matrix stability in the Achilles tendon (Reddy et al., 2002, Arch. Biochem. Biophys., 399, 174–180). The present study was designed to gain further insight into glycation-induced collagen cross-linking and its relationship to matrix stiffness in the rabbit Achilles tendo...

  1. Fluorescence imaging of tryptophan and collagen cross-links to evaluate wound closure ex vivo

    Science.gov (United States)

    Wang, Ying; Ortega-Martinez, Antonio; Farinelli, Bill; Anderson, R. R.; Franco, Walfre

    2016-02-01

    Wound size is a key parameter in monitoring healing. Current methods to measure wound size are often subjective, time-consuming and marginally invasive. Recently, we developed a non-invasive, non-contact, fast and simple but robust fluorescence imaging (u-FEI) method to monitor the healing of skin wounds. This method exploits the fluorescence of native molecules to tissue as functional and structural markers. The objective of the present study is to demonstrate the feasibility of using variations in the fluorescence intensity of tryptophan and cross-links of collagen to evaluate proliferation of keratinocyte cells and quantitate size of wound during healing, respectively. Circular dermal wounds were created in ex vivo human skin and cultured in different media. Two serial fluorescence images of tryptophan and collagen cross-links were acquired every two days. Histology and immunohistology were used to validate correlation between fluorescence and epithelialization. Images of collagen cross-links show fluorescence of the exposed dermis and, hence, are a measure of wound area. Images of tryptophan show higher fluorescence intensity of proliferating keratinocytes forming new epithelium, as compared to surrounding keratinocytes not involved in epithelialization. These images are complementary since collagen cross-links report on structure while tryptophan reports on function. HE and immunohistology show that tryptophan fluorescence correlates with newly formed epidermis. We have established a fluorescence imaging method for studying epithelialization processes during wound healing in a skin organ culture model, our approach has the potential to provide a non-invasive, non-contact, quick, objective and direct method for quantitative measurements in wound healing in vivo.

  2. Validity of autorefractor based screening method for irregular astigmatism compared to the corneal topography- a cross sectional study

    Directory of Open Access Journals (Sweden)

    Alicia Galindo-Ferreiro

    2017-09-01

    Full Text Available AIM: To present a method of screening for irregular astigmatism with an autorefractor and its determinants compared to corneal topography. METHODS: This cross-sectional validity study was conducted in 2013 at an eye hospital in Spain. A tabletop autorefractor (test 1 was used to measure the refractive status of the anterior surface of the cornea at two corneal meridians of each eye. Then corneal topography (test 2 and Bogan’s classification was used to group eyes into those with regular or no astigmatism (GRI and irregular astigmatism (GRII. Test 1 provided a single absolute value for the greatest cylinder difference (Vr. The receiver operating characteristic (ROC were plotted for the Vr values measured by test 1 for GRI and GRII eyes. On the basis a Vr value of 1.25 D as cut off, sensitivity, specificity were also calculated. RESULTS: The study sample was comprised of 260 eyes (135 patients. The prevalence of irregular astigmatism was 42% [95% confidence interval (CI: 36, 48]. Based on test 2, there were 151 eyes in GRI and 109 eyes in GRII. The median Vr was 0.75 D (25% quartile, 0.5 D for GRI and 1.75 D (25% quartile, 1.25 D for GRII. The area under curve was 0.171 for GRI and 0.83 for GRII. The sensitivity of test I was 78.1% and the specificity was 76.1%. CONCLUSION: A conventional autorefractor can be effective as a first level screening method to detect irregular corneal astigmatism in places where corneal topography facilities are not available.

  3. Confocal microscopy evaluation of stromal fluorescence intensity after standard and accelerated iontophoresis-assisted corneal cross-linking.

    Science.gov (United States)

    Lanzini, Manuela; Curcio, Claudia; Spoerl, Eberhard; Calienno, Roberta; Mastropasqua, Alessandra; Colasante, Martina; Mastropasqua, Rodolfo; Nubile, Mario; Mastropasqua, Leonardo

    2017-02-01

    The aim of this study is to determine modifications in stromal fluorescence intensity after different corneal cross-linking (CXL) procedures and to correlate stromal fluorescence to corneal biomechanical resistance. For confocal microscopy study, 15 human cadaver corneas were examined. Three served as control (group 1), three were just soaked with iontophoresis procedure (group 2), three were treated with standard epi-off technique (group 3), and six underwent iontophoresis imbibition. Three of later six were irradiated for 30 min with 3 mW/cm 2 UVA (group 4) and three for 9 min at 10 mW/cm 2 UVA (group 5). Confocal microscopy was performed to quantify the fluorescence intensity in the cornea at different stromal depths. For biomechanical study, 30 human cadaver corneas were randomly divided into five groups and treated as previously described. Static stress-strain measurements of the corneas were performed. Iontophoresis imbibition followed by 10mW/cm 2 irradiation proved to increase stromal fluorescence into the corneal stroma and significant differences were revealed between group 3 and 5 both at 100 (p = 0.0171) and 250 µm (p = 0.0024), respectively. Biomechanical analysis showed an improvement of corneal resistance in group 5. Iontophoresis imbibition followed by accelerated irradiation increased the stromal fluorescence and is related to an improvement of biomechanical resistance. This approach may represent a new strategy to achieve greater concentrations of riboflavin without removing corneal epithelium and improve clinical results while reducing the side effects of CXL.

  4. Studies on Cross-linking of succinic acid with chitosan/collagen

    Directory of Open Access Journals (Sweden)

    Tapas Mitra

    2013-01-01

    Full Text Available The present study summarizes the cross-linking property of succinic acid with chitosan /collagen. In detail, the chemistry behind the cross-linking and the improvement in mechanical and thermal properties of the cross-linked material were discussed with suitable instruments and bioinformatics tools. The concentration of succinic acid with reference to the chosen polymers was optimized. A 3D scaffold prepared using an optimized concentration of succinic acid (0.2% (w/v with chitosan (1.0% (w/v and similarly with collagen (0.5% (w/v, was subjected to surface morphology, FT-IR analysis, tensile strength assessment, thermal stability and biocompatibility. Results revealed, cross-linking with succinic acid impart appreciable mechanical strength to the scaffold material. In silico analysis suggested the prevalence of non-covalent interactions, which played a crucial role in improving the mechanical and thermal properties of the cross-linked scaffold. The resultant 3D scaffold may find application as wound dressing material, as an implant in clinical applications and as a tissue engineering material.

  5. Disentangling mechanisms involved in collagen pyridinoline cross-linking : The immunophilin FKBP65 is critical for dimerization of lysyl hydroxylase 2

    NARCIS (Netherlands)

    Gjaltema, Rutger A. F.; van der Stoel, Miesje M.; Boersema, Miriam; Bank, Ruud A.

    2016-01-01

    Collagens are subjected to extensive posttranslational modifications, such as lysine hydroxylation. Bruck syndrome (BS) is a connective tissue disorder characterized at the molecular level by a loss of telopeptide lysine hydroxylation, resulting in reduced collagen pyridinoline cross-linking. BS

  6. University students' knowledge of corneal donation and willingness to donate corneas in the occupied Palestinian territory: a cross-sectional study.

    Science.gov (United States)

    Al-Labadi, Liana; Gammoh, Yazan; Shehada, Reham; Shahin, Reem; Jbarah, Walaa; Amro, Madleen; Athamny, Hanan

    2018-02-21

    Access to corneal transplantation is limited worldwide because of poor knowledge. Ethical, religious, and cultural barriers contribute to low rates of corneal donation. In the occupied Palestinian territory, limited information is available on factors affecting corneal donation. The aim of this study was to assess the knowledge and willingness towards corneal donation in Palestinian students. This cross-sectional study included university students selected through convenience sampling in Nablus in the summer of 2016. The sample size was determined using the sample formulae and a 15% non-response rate. All students registered in obligatory courses were included in the study after verbal consent. Each participant was given a self-administered questionnaire consisting of 14 questions to assess knowledge, awareness, and willingness toward corneal donation. Frequencies were used for descriptive analysis, and associations were determined using multivariate analysis and χ 2 test, with a p value of less than 0·05 considered significant. Of the 634 students completing the questionnaire, 411 (65%) were women, 614 (97%) were Muslims, and 155 (25%) were health or medical students. 592 (93%) respondents were unaware of eye bank availability, and 407 (69%; p=0.002) of these respondents did not show willingness towards corneal donation. 431 (67%) respondents were aware of a lack in corneal donation, but 274 (64%; p=0·01) of these respondents did not show willingness towards corneal donation. 429 (68%) respondents were not willing to donate their corneas, the most common reasons being disapproval by family members and poor awareness. We found no association between sociodemographic factors and willingness was determined. Palestinian students are aware of the lack of local cornea donation but are unwilling to donate their corneas. The study results are not representative of the entire population because of the homogeneous nature of the sample. Large efforts are needed locally to

  7. Clinical evaluation and induced corneal vascularization study by native and anionic collagen membranes in rabbits corneas Avaliação clínica e estudo da vascularização corneal induzida pelas membranas de colágeno nativo e aniônico em córneas de coelhos

    Directory of Open Access Journals (Sweden)

    Thaís Eliane Binotto

    2009-12-01

    Full Text Available PURPOSE: To evaluate the corneal vascularization (CV and the clinical aspects induced by interlamellar graft with native (NCM and anionic (ACM collagen membranes in rabbits corneas. METHODS: An interlamellar graft with a 0.25 x 0.25 cm NCM (group 1 or ACM (group 2 fragment was performed in the right eye (treated eye. In the left eye, an estromal tunnel was done (control eye. Sixteen rabbits were used, and they were subdivided into two experimental groups of eight animals each. The clinical evaluation was performed at the 1st, 3rd, 7th, 15th and 30th postoperative days. Corneal vascularization analysis was performed after 30 days by the Images Analizator System Leica Qwin-550®. RESULTS: After 7 days, corneal vascularization was observed at about 2.25 ± 0.71 mm (NCM and at about 1.0 ± 1.69 mm (ACM, respectively, from the limbus in direction to the central cornea. After 15 days, CV increased in both groups (5.25 ± 1.03 mm - NCM; 2.0 ± 2.39 mm - ACM and then progressively decreased until day 30 (2.25 ± 2.10 mm - NCM; 0.75 ± 2.12 mm - ACM. The statistical analysis indicated that the averages of the distances from the limb vessels to the grafts observed after 7 and 15 days had not differed statistically (p=0.17, and after 15 and 30 postoperative days had a tendency to differ statistically (p=0.09. The control eyes did not present any changes. CONCLUSION: The interlamellar graft with native and anionic collagen membranes induced corneal vascularization when applied to rabbit corneas, but anionic collagen membrane induced a smaller corneal vascularization when compared to native collagen membrane. Although further studies are required, the results found in this study demonstrated the usefulness of interlamellar graft with native and anionic collagen membranes in keratoplasties. These membranes consists in one more graft option for the surgical treatment of corneal repair in rabbits and others animals, when other forms of medical and surgical

  8. Quantitative Raman characterization of cross-linked collagen thin films as a model system for diagnosing early osteoarthritis

    Science.gov (United States)

    Wang, Chao; Durney, Krista M.; Fomovsky, Gregory; Ateshian, Gerard A.; Vukelic, Sinisa

    2016-03-01

    The onset of osteoarthritis (OA)in articular cartilage is characterized by degradation of extracellular matrix (ECM). Specifically, breakage of cross-links between collagen fibrils in the articular cartilage leads to loss of structural integrity of the bulk tissue. Since there are no broadly accepted, non-invasive, label-free tools for diagnosing OA at its early stage, Raman spectroscopyis therefore proposed in this work as a novel, non-destructive diagnostic tool. In this study, collagen thin films were employed to act as a simplified model system of the cartilage collagen extracellular matrix. Cross-link formation was controlled via exposure to glutaraldehyde (GA), by varying exposure time and concentration levels, and Raman spectral information was collected to quantitatively characterize the cross-link assignments imparted to the collagen thin films during treatment. A novel, quantitative method was developed to analyze the Raman signal obtained from collagen thin films. Segments of Raman signal were decomposed and modeled as the sum of individual bands, providing an optimization function for subsequent curve fitting against experimental findings. Relative changes in the concentration of the GA-induced pyridinium cross-links were extracted from the model, as a function of the exposure to GA. Spatially resolved characterization enabled construction of spectral maps of the collagen thin films, which provided detailed information about the variation of cross-link formation at various locations on the specimen. Results showed that Raman spectral data correlate with glutaraldehyde treatment and therefore may be used as a proxy by which to measure loss of collagen cross-links in vivo. This study proposes a promising system of identifying onset of OA and may enable early intervention treatments that may serve to slow or prevent osteoarthritis progression.

  9. A two-year's results of iontophoresis-assisted transepithelial corneal cross-linking for progressive keratoconus

    Directory of Open Access Journals (Sweden)

    Hong-Zhen Jia

    2016-07-01

    Full Text Available AIM: To report a two-year's results of iontophoresis-assisted transepithelial corneal cross-linking(I-CXLfor progressive keratoconus. METHODS: Thirty-four eyes in 24 patients with progressive keratoconus(mean age 21.0±5.6 years; range: 14-32 yearswere treated. After 1g/L riboflavin-distilled water solution was administered by iontophoresis-assited(current 1mAtransepithelial method for 5min in total, standard surface UVA irradiation(370nm, 3mW/cm2was performed at a 1-cm distance for 30min. The best corrected visual acuity(BCVAmeasured as LogMAR number, corneal refractive astigmatism, K1, K2, Kmean, Kmax, intraocular pressure, endothelial cell density, the thickness at corneal apex and the thinnest point were measured preoperatively and 2a postoperatively. RESULTS:At 2a after the procedure, BCVA(LogMARimproved from 0.32±0.25 to 0.25±0.19(t=2.849, P=0.015. K1 decreased from 47.12±4.33 to 46.06±4.77(t=2.652, P=0.015. K2 decreased from 51.36±5.59 to 50.40±6.16(t=2.121, P=0.047. Kmean decreased from 49.12±4.76 to 48.10±5.25(t=2.663, P=0.015. Kmax decreased from 57.57±8.30 to 55.91±8.14(t=2.398, P=0.026. The corneal apex thickness decreased from 476.90±38.71μm to 454.43±40.86μm(t=2.853, P=0.010. The thinnest thickness decreased from 464.38±39.92μm to 433.86±50.78μm(t=3.485, P=0.002. Corneal refractive astigmatism, intraocular pressure and endothelial cell density did not show significant changes. CONCLUSION: I-CXL for progressive keratoconus is safe and effective which can prevent deterioration of progressive keratoconus within 2a, but further long-term studies are necessary still.

  10. Corneal Laceration

    Medline Plus

    Full Text Available ... Eye Health A-Z Symptoms Glasses & Contacts Tips & Prevention News Ask an Ophthalmologist Patient Stories Español Eye ... Causes Corneal Laceration? Corneal Laceration Diagnosis Corneal Laceration Treatment What Is Corneal Laceration? Leer en Español: ¿Qué ...

  11. Chemical structure, biosynthesis and synthesis of free and glycosylated pyridinolines formed by cross-link of bone and synovium collagen.

    Science.gov (United States)

    Anastasia, Luigi; Rota, Paola; Anastasia, Mario; Allevi, Pietro

    2013-09-21

    This review focuses on the chemical structure, biosynthesis and synthesis of free and glycosylated pyridinolines (Pyds), fluorescent collagen cross-links, with a pyridinium salt structure. Pyds derive from the degradation of bone collagen and have attracted attention for their use as biochemical markers of bone resorption and to assess fracture risk prediction in persons suffering from osteoporosis, bone cancer and other bone or collagen diseases. We consider and critically discuss all reported syntheses of free and glycosylated Pyds evidencing an unrevised chemistry, original and of general utility, analysis of which allows us to also support a previously suggested non-enzymatic formation of Pyds in collagen better rationalizing and justifying the chemical events.

  12. Comparison of sequential vs same-day simultaneous collagen cross-linking and topography-guided PRK for treatment of keratoconus.

    Science.gov (United States)

    Kanellopoulos, Anastasios John

    2009-09-01

    The safety and efficacy of corneal collagen cross-linking (CXL) and topography-guided photorefractive keratectomy (PRK) using a different sequence and timing were evaluated in consecutive keratoconus cases. This study included a total of 325 eyes with keratoconus. Eyes were divided into two groups. The first group (n=127 eyes) underwent CXL with subsequent topography-guided PRK performed 6 months later (sequential group) and the second group (n=198 eyes) underwent CXL and PRK in a combined procedure on the same day (simultaneous group). Statistical differences were examined for pre- to postoperative changes in uncorrected (UCVA, logMAR) and best-spectacle-corrected visual acuity (BSCVA, logMAR), manifest refraction spherical equivalent (MRSE), keratometry (K), topography, central corneal thickness, endothelial cell count, corneal haze, and ectatic progression. Mean follow-up was 36+/-18 months (range: 24 to 68 months). At last follow-up in the sequential group, the mean UCVA improved from 0.9+/-0.3 logMAR to 0.49+/-0.25 logMAR, and mean BSCVA from 0.41+/-0.25 logMAR to 0.16+/-0.22 logMAR. Mean reduction in spherical equivalent refraction was 2.50+/-1.20 diopters (D), mean haze score was 1.2+/-0.5, and mean reduction in K was 2.75+/-1.30 D. In the simultaneous group, mean UCVA improved from 0.96+/-0.2 logMAR to 0.3+/-0.2 logMAR, and mean BSCVA from 0.39+/-0.3 logMAR to 0.11+/-0.16 logMAR. Mean reduction in spherical equivalent refraction was 3.20+/-1.40 D, mean haze score was 0.5+/-0.3, and mean reduction in K was 3.50+/-1.3 D. Endothelial cell count preoperatively and at last follow-up was unchanged (PPRK and CXL appears to be superior to sequential CXL with later PRK in the visual rehabilitation of progressing keratoconus. Copyright 2009, SLACK Incorporated.

  13. Transepithelial Riboflavin Absorption in an Ex Vivo Rabbit Corneal Model.

    Science.gov (United States)

    Gore, Daniel M; O'Brart, David; French, Paul; Dunsby, Chris; Allan, Bruce D

    2015-07-01

    To measure depth-specific riboflavin concentrations in corneal stroma using two-photon fluorescence microscopy and compare commercially available transepithelial corneal collagen cross-linking (CXL) protocols. Transepithelial CXL riboflavin preparations--MedioCross TE, Ribocross TE, Paracel plus VibeX Xtra, and iontophoresis with Ricrolin+--were applied to the corneal surface of fresh postmortem rabbit eyes in accordance with manufacturers' recommendations for clinical use. Riboflavin 0.1% (VibeX Rapid) was applied after corneal epithelial debridement as a positive control. After riboflavin application, eyes were snap frozen in liquid nitrogen. Corneal cross sections 35-μm thick were cut on a cryostat, mounted on a slide, and imaged by two-photon fluorescence microscopy. Mean (SD) concentrations were calculated from five globes tested for each protocol. Peak riboflavin concentration of 0.09% (± 0.01) was observed within the most superficial stroma (stromal depth 0-10 μm) in positive controls (epithelium-off). At the same depth, peak stromal riboflavin concentrations for MedioCross TE, Ricrolin+, Paracel/Xtra, and Ribocross TE were 0.054% (± 0.01), 0.031% (0.003), 0.021% (± 0.001), and 0.015% (± 0.004), respectively. At a depth of 300 μm (within the demarcation zone commonly seen after corneal cross-linking), the stromal concentration in epithelium-off positive controls was 0.075% (± 0.006), while at the same depth MedioCross TE and Ricrolin+ achieved 0.018% (± 0.006) and 0.016% (0.002), respectively. None of the remaining transepithelial protocols achieved concentrations above 0.005% at this same 300-μm depth. Overall, MedioCross TE was the best-performing transepithelial formulation. Corneal epithelium is a significant barrier to riboflavin absorption into the stroma. Existing commercial transepithelial CXL protocols achieve relatively low riboflavin concentrations in the anterior corneal stroma when compared to gold standard epithelium-off absorption

  14. Modification of mature non-reducible collagen cross-link concentrations in bovine m. gluteus medius and semitendinosus with steer age at slaughter, breed cross and growth promotants.

    Science.gov (United States)

    Roy, B C; Sedgewick, G; Aalhus, J L; Basarab, J A; Bruce, H L

    2015-12-01

    Increased meat toughness with animal age has been attributed to mature trivalent collagen cross-link formation. Intramuscular trivalent collagen cross-link content may be decreased by reducing animal age at slaughter and/or inducing muscle re-modeling with growth promotants. This hypothesis was tested in m. gluteus medius (GM) and m. semitendinosus (ST) from 112 beef steers finished at either 12 to 13 (rapid growth) or 18 to 20 (slow growth) months of age. Hereford-Aberdeen Angus (HAA) or Charolais-Red Angus (CRA) steers were randomly assigned to receive implants (IMP), ractopamine (RAC), both IMP and RAC, or none (control). RAC decreased pyridinoline (mol/mol collagen) and IMP increased Ehrlich chromogen (EC) (mol/mol collagen) in the GM. In the ST, RAC increased EC (mol/mol collagen) but decreased EC (nmol/g raw muscle) in slow growing CRA steers. Also, IMP increased ST pyridinoline (nmol/g raw muscle) of slow-growing HAA steers. Results indicated alteration of perimysium collagen cross-links content in muscle in response to growth promotants. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Hyperopic correction: clinical validation with epithelium-on and epithelium-off protocols, using variable fluence and topographically customized collagen corneal crosslinking

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2014-12-01

    Full Text Available Anastasios John Kanellopoulos,1,2 George Asimellis1 1LaserViison.gr Clinical and Research Eye Institute, Athens, Greece; 2Department of Ophthalmology, New York University Medical School, New York, NY, USAPurpose: To report novel application of topographically-customized collagen crosslinking aiming to achieve hyperopic refractive changes. Two approaches were evaluated, one based on epithelium-off and one based on epithelium-on (transepithelial. Methods: A peripheral annular-shaped topographically customizable design was employed for high-fluence ultraviolet (UV-A irradiation aiming to achieve hyperopic refractive changes. A total of ten eyes were involved in this study. In group-A (five eyes, a customizable ring pattern was employed to debride the epithelium by excimer laser ablation, while in group-B (also five eyes, the epithelium remained intact. In both groups, specially formulated riboflavin solutions were applied. Visual acuity, cornea clarity, keratometry, topography, and pachymetry with a multitude of modalities, as well as endothelial cell counts were evaluated. Results: One year postoperatively, the following changes have been noted: in group-A, average uncorrected distance visual acuity changed from 20/63 to 20/40. A mean hyperopic refractive increase of +0.75 D was achieved. There was some mild reduction in the epithelial thickness. In group-B, average uncorrected distance visual acuity changed from 20/70 to 20/50. A mean hyperopic refractive increase of +0.85 D was achieved. Epithelial thickness returned to slightly reduced levels (compared to baseline in group-A, whereas to slightly increased levels in group-B. Conclusion: We introduce herein the novel application of a topographically-customizable collagen crosslinking to achieve a hyperopic refractive effect. This novel technique may be applied either with epithelial removal, offering a more stable result or with a non-ablative and non-incisional approach, offering a minimally

  16. RELATIONS BETWEEN INVITRO CYTOTOXICITY AND CROSS-LINKED DERMAL SHEEP COLLAGENS

    NARCIS (Netherlands)

    VANLUYN, MJA; VANWACHEM, PB; DAMINK, LO; DIJKSTRA, PJ; FEIJEN, J; NIEUWENHUIS, P

    Collagen-based biomaterials have found various applications in the biomedical field. However, collagen-based biomaterials may induce cytotoxic effects. This study evaluated possible cytotoxic effects of (crosslinked) dermal sheep collagen (DSC) using a 7-d-methylcellulose cell culture with human

  17. Lower strength of the human posterior patellar tendon seems unrelated to mature collagen cross-linking and fibril morphology

    DEFF Research Database (Denmark)

    Hansen, Philip; Haraldsson, Bjarki Thor; Aagaard, Per

    2010-01-01

    The human patellar tendon is frequently affected by tendinopathy, but the etiology of the condition is not established, although differential loading of the anterior and posterior tendon may be associated with the condition. We hypothesized that changes in fibril morphology and collagen cross-lin...

  18. Tranexamic acid, an inhibitor of plasminogen activation, reduces urinary collagen cross-link excretion in both experimental and rheumatoid arthritis

    NARCIS (Netherlands)

    Ronday, H.K.; TeKoppele, J.M.; Greenwald, R.A.; Moak, S.A.; Roos, J.A.D.M. de; Dijkmans, B.A.C.; Breedveld, F.C.; Verheijen, J.H.

    1998-01-01

    The plasminogen activation system is one of the enzyme systems held responsible for bone and cartilage degradation in rheumatoid arthritis (RA). In this study, we evaluated the effect of tranexamic acid (TEA), an inhibitor of plasminogen activation, on urinary collagen cross-link excretion and

  19. Determination of the relationship between collagen cross-links and the bone-tissue stiffness in the porcine mandibular condyle

    NARCIS (Netherlands)

    Willems, N.M.B.K.; Mulder, L.; Bank, R.A.; Grünheid, T.; Toonder, J.M.J. den; Zentner, A.; Langenbach, G.E.J.

    2011-01-01

    Although bone-tissue stiffness is closely related to the degree to which bone has been mineralized, other determinants are yet to be identified. We, therefore, examined the extent to which the mineralization degree, collagen, and its cross-links are related to bone-tissue stiffness. A total of 50

  20. Effect of pore size and cross-linking of a novel collagen-elastin dermal substitute on wound healing

    NARCIS (Netherlands)

    Boekema, B.K.H.L.; Vlig, M.; Damink, L.O.; Middelkoop, E.; Eummelen, L.; Buhren, A.V.; Ulrich, M.M.W.

    2014-01-01

    Collagen-elastin (CE) scaffolds are frequently used for dermal replacement in the treatment of full-thickness skin defects such as burn wounds. But little is known about the optimal pore size and level of cross-linking. Different formulations of dermal substitutes with unidirectional pores were

  1. Evaluation of the shifting of the line of sight and higher order aberrations of eyes with keratoconus after corneal cross-linking.

    Science.gov (United States)

    Kosekahya, Pinar; Koc, Mustafa; Tekin, Kemal; Uzel, Murat; Atilgan, Cemile Ucgul; Caglayan, Mehtap; Yilmazbas, Pelin

    2017-10-01

    To evaluate changes in the coordinates of the line of sight (LoS) and higher order aberrations (HOAs) of eyes with keratoconus, following corneal cross-linking (CXL). All patients (93 eyes) underwent detailed ophthalmologic examination and Pentacam HR measurements at baseline and at 3, 6, and 12 months after corneal CXL. LoS coordinates on the horizontal (x) and vertical (y) axes, vertical coma, vertical trefoil, spherical aberration, total root-mean square (RMS), and HOA-RMS values were recorded along with visual acuity and topographical parameters. LoS significantly shifted to the nasal region after corneal CXL in both right and left eyes (p=0.003 and p=0.01, respectively). Horizontal axis values of both eyes significantly shifted to the temporal region at postoperative 6th months compared to the baseline measurements (p=0.02 and p=0.02, respectively) and remained the same between postoperative 6th months and 12th months (p=1.00 and p=0.97, respectively). Total-RMS, HOA-RMS, vertical coma, and spherical aberration values significantly improved after corneal CXL (pbaseline measurements (p=0.003, p=0.02, p0.05 for all values). The changes in horizontal-axis coordinates in left eyes were significantly correlated with anterior elevation, anterior astigmatism, total-RMS and HOA-RMS changes (r 2 =0.20, p=0.03; r 2 =0.35, pshifted to the nasal region and HOAs improved after corneal CXL and these changes stabilized 6th months after corneal CXL. It would be more better to perform refractive surgery in crosslinked corneas at least 6th months after corneal CXL. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  2. Fabrication of Collagen Gel Hollow Fibers by Covalent Cross-Linking for Construction of Bioengineering Renal Tubules.

    Science.gov (United States)

    Shen, Chong; Zhang, Guoliang; Wang, Qichen; Meng, Qin

    2015-09-09

    Collagen, the most used natural biomacromolecule, has been extensively utilized to make scaffolds for cell cultures in tissue engineering, but has never been fabricated into the configuration of a hollow fiber (HF) for cell culture due to its poor mechanical properties. In this study, renal tubular cell-laden collagen hollow fiber (Col HF) was fabricated by dissolving sacrificial Ca-alginate cores from collagen shells strengthened by carbodiimide cross-linking. The inner/outer diameters of the Col HF were precisely controlled by the flow rates of core alginate/shell collagen solution in the microfluidic device. As found, the renal tubular cells self-assembled into renal tubules with diameters of 50-200 μm post to the culture in Col HF for 10 days. According to the 3D reconstructed confocal images or HE staining, the renal cells appeared as a tight tubular monolayer on the Col HF inner surface, sustaining more 3D cell morphology than the cell layer on the 2D flat collagen gel surface. Moreover, compared with the cultures in either a Transwell or polymer HF membrane, the renal tubules in Col HF exhibited at least 1-fold higher activity on brush border enzymes of alkaline phosphatase and γ-glutamyltransferase, consistent with their gene expressions. The enhancement occurred similarly on multidrug resistance protein 2 and glucose uptake. Such bioengineered renal tubules in Col HF will present great potential as alternatives to synthetic HF in both clinical use and pharmaceutical investigation.

  3. Diaphragm Repair with a Novel Cross-Linked Collagen Biomaterial in a Growing Rabbit Model.

    Directory of Open Access Journals (Sweden)

    Steffi Mayer

    Full Text Available Neonates with congenital diaphragmatic hernia and large defects often require patch closure. Acellular collagen matrices (ACM have been suggested as an alternative to synthetic durable patches as they are remodeled by the host or could also be used for tissue engineering purposes.2.0x1.0 cm diaphragmatic defects were created in 6-weeks old New-Zealand white rabbits. We compared reconstruction with a purpose-designed cross-linked ACM (Matricel to 4-layer non-cross-linked small intestinal submucosa (SIS and a 1-layer synthetic Dual Mesh (Gore-Tex. Unoperated animals or animals undergoing primary closure (4/0 polyglecaprone served as age-matched controls. 60 (n = 25 resp. 90 (n = 17 days later, animals underwent chest x-ray and obduction for gross examination of explants, scoring of adhesion and inflammatory response. Also, uniaxial tensiometry was done, comparing explants to contralateral native diaphragmatic tissue.Overall weight nearly doubled from 1,554±242 g at surgery to 2,837±265 g at obduction (+84%. X-rays did show rare elevation of the left diaphragm (SIS = 1, Gore-Tex = 1, unoperated control = 1, but no herniation of abdominal organs. 56% of SIS and 10% of Matricel patches degraded with visceral bulging in four (SIS = 3, Matricel = 1. Adhesion scores were limited: 0.5 (Matricel to 1 (SIS, Gore-Tex to the left lung (p = 0.008 and 2.5 (Gore-Tex, 3 (SIS and 4 (Matricel to the liver (p<0.0001. Tensiometry revealed a reduced bursting strength but normal compliance for SIS. Compliance was reduced in Matricel and Gore-Tex (p<0.01. Inflammatory response was characterized by a more polymorphonuclear cell (SIS resp. macrophage (Matricel type of infiltrate (p<0.05. Fibrosis was similar for all groups, except there was less mature collagen deposited to Gore-Tex implants (p<0.05.Matricel induced a macrophage-dominated inflammatory response, more adhesions, had appropriate strength but a lesser compliance compared to native tissue. The herein

  4. Characterization of cross-linked porous gelatin carriers and their interaction with corneal endothelium: biopolymer concentration effect.

    Directory of Open Access Journals (Sweden)

    Jui-Yang Lai

    Full Text Available Cell sheet-mediated tissue regeneration is a promising approach for corneal reconstruction. However, the fragility of bioengineered corneal endothelial cell (CEC monolayers allows us to take advantage of cross-linked porous gelatin hydrogels as cell sheet carriers for intraocular delivery. The aim of this study was to further investigate the effects of biopolymer concentrations (5-15 wt% on the characteristic and safety of hydrogel discs fabricated by a simple stirring process combined with freeze-drying method. Results of scanning electron microscopy, porosity measurements, and ninhydrin assays showed that, with increasing solid content, the pore size, porosity, and cross-linking index of carbodiimide treated samples significantly decreased from 508±30 to 292±42 µm, 59.8±1.1 to 33.2±1.9%, and 56.2±1.6 to 34.3±1.8%, respectively. The variation in biopolymer concentrations and degrees of cross-linking greatly affects the Young's modulus and swelling ratio of the gelatin carriers. Differential scanning calorimetry measurements and glucose permeation studies indicated that for the samples with a highest solid content, the highest pore wall thickness and the lowest fraction of mobile water may inhibit solute transport. When the biopolymer concentration is in the range of 5-10 wt%, the hydrogels have high freezable water content (0.89-0.93 and concentration of permeated glucose (591.3-615.5 µg/ml. These features are beneficial to the in vitro cultivation of CECs without limiting proliferation and changing expression of ion channel and pump genes such as ATP1A1, VDAC2, and AQP1. In vivo studies by analyzing the rabbit CEC morphology and count also demonstrate that the implanted gelatin discs with the highest solid content may cause unfavorable tissue-material interactions. It is concluded that the characteristics of cross-linked porous gelatin hydrogel carriers and their triggered biological responses are in relation to biopolymer

  5. Corneal biomechanical properties from air-puff corneal deformation imaging

    Science.gov (United States)

    Marcos, Susana; Kling, Sabine; Bekesi, Nandor; Dorronsoro, Carlos

    2014-02-01

    The combination of air-puff systems with real-time corneal imaging (i.e. Optical Coherence Tomography (OCT), or Scheimpflug) is a promising approach to assess the dynamic biomechanical properties of the corneal tissue in vivo. In this study we present an experimental system which, together with finite element modeling, allows measurements of corneal biomechanical properties from corneal deformation imaging, both ex vivo and in vivo. A spectral OCT instrument combined with an air puff from a non-contact tonometer in a non-collinear configuration was used to image the corneal deformation over full corneal cross-sections, as well as to obtain high speed measurements of the temporal deformation of the corneal apex. Quantitative analysis allows direct extraction of several deformation parameters, such as apex indentation across time, maximal indentation depth, temporal symmetry and peak distance at maximal deformation. The potential of the technique is demonstrated and compared to air-puff imaging with Scheimpflug. Measurements ex vivo were performed on 14 freshly enucleated porcine eyes and five human donor eyes. Measurements in vivo were performed on nine human eyes. Corneal deformation was studied as a function of Intraocular Pressure (IOP, 15-45 mmHg), dehydration, changes in corneal rigidity (produced by UV corneal cross-linking, CXL), and different boundary conditions (sclera, ocular muscles). Geometrical deformation parameters were used as input for inverse finite element simulation to retrieve the corneal dynamic elastic and viscoelastic parameters. Temporal and spatial deformation profiles were very sensitive to the IOP. CXL produced a significant reduction of the cornea indentation (1.41x), and a change in the temporal symmetry of the corneal deformation profile (1.65x), indicating a change in the viscoelastic properties with treatment. Combining air-puff with dynamic imaging and finite element modeling allows characterizing the corneal biomechanics in-vivo.

  6. Dermal regeneration in native non-cross-linked collagen sponges with different extracellular matrix molecules

    NARCIS (Netherlands)

    de Vries, H. J.; Middelkoop, E.; Mekkes, J. R.; Dutrieux, R. P.; Wildevuur, C. H.; Westerhof, H.

    1994-01-01

    Collagenous dermal templates can prevent scarring and wound contraction in the healing of full-thickness defects. In a porcine wound model, full-thickness wounds were substituted by reconstituted and native collagen sponges in combination with autologous split-skin mesh grafts and covered with a

  7. Are the surgeons safe during UV-A radiation exposure in collagen cross-linking procedure?

    Science.gov (United States)

    Shetty, Rashmi; Shetty, Rohit; Mahendradas, Padmamalini; Shetty, Bhujang K

    2012-02-01

    To quantify the effect of scattered UV-A radiation used in the collagen cross-linking (CXL) procedure and the amount of radiation reaching the surgeon and the surrounding area and to estimate the dampening effect by various protective devices. In this case series, 3 patients [aged 25-30 (±2.5) years] with keratoconus underwent a CXL procedure with UV-A light and riboflavin. Irradiance was measured using a spectrometer (Model USB2000; Ocean Optics, Inc) for various distances from the source, at various angles, and for different durations of radiation. The spectrometer was also used to measure the dampening effect produced by gown, latex gloves, and UV-protective glasses. Maximum UV-A radiation (1.4 × 10(-9) mW/cm(2)) was measured at 2 cm from the limbus, when the probe was held at a 45-degree angle to the floor. UV-A radiation reaching the surgeon's eye and the abdomen was 3.403 × 10(-11) and 2.36 × 10(-11) mW/cm(2), respectively. Gown, latex gloves, and UV-protective glasses showed dampening effects of 99.58%, 95.01%, and 99.73%, respectively. CXL appears to be a safe procedure with respect to UV-A radiation exposure to the surgeon. Further safety can be ensured by UV-protective devices.

  8. Regulation of corneal stroma extracellular matrix assembly.

    Science.gov (United States)

    Chen, Shoujun; Mienaltowski, Michael J; Birk, David E

    2015-04-01

    The transparent cornea is the major refractive element of the eye. A finely controlled assembly of the stromal extracellular matrix is critical to corneal function, as well as in establishing the appropriate mechanical stability required to maintain corneal shape and curvature. In the stroma, homogeneous, small diameter collagen fibrils, regularly packed with a highly ordered hierarchical organization, are essential for function. This review focuses on corneal stroma assembly and the regulation of collagen fibrillogenesis. Corneal collagen fibrillogenesis involves multiple molecules interacting in sequential steps, as well as interactions between keratocytes and stroma matrix components. The stroma has the highest collagen V:I ratio in the body. Collagen V regulates the nucleation of protofibril assembly, thus controlling the number of fibrils and assembly of smaller diameter fibrils in the stroma. The corneal stroma is also enriched in small leucine-rich proteoglycans (SLRPs) that cooperate in a temporal and spatial manner to regulate linear and lateral collagen fibril growth. In addition, the fibril-associated collagens (FACITs) such as collagen XII and collagen XIV have roles in the regulation of fibril packing and inter-lamellar interactions. A communicating keratocyte network contributes to the overall and long-range regulation of stromal extracellular matrix assembly, by creating micro-domains where the sequential steps in stromal matrix assembly are controlled. Keratocytes control the synthesis of extracellular matrix components, which interact with the keratocytes dynamically to coordinate the regulatory steps into a cohesive process. Mutations or deficiencies in stromal regulatory molecules result in altered interactions and deficiencies in both transparency and refraction, leading to corneal stroma pathobiology such as stromal dystrophies, cornea plana and keratoconus. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Photorefractive keratectomy with corneal collagen cross-linking 1 year after intrastromal corneal ring segment implantation for the treatment of keratoconus

    Directory of Open Access Journals (Sweden)

    Maha Elfayoumi

    2016-01-01

    Conclusion PRK with CXL can be used to enhance aided and unaided visual acuity after treatment of keratoconus with Intacs implants, with a stable refractive outcome, and could postpone penetrating or lamellar keratoplasty in patients with the visually disabling disease of moderate keratoconus.

  10. [Dynamics of riboflavin level in aqueous humour of anterior chamber of experimental animals under standard stroma saturation by ultraviolet corneal cross-linking solutions].

    Science.gov (United States)

    Bikbov, M M; Shevchuk, N E; Khalimov, A R; Bikbova, G M

    To evaluate the dynamics of riboflavin changes in the aqueous humour of the anterior chamber (AHAC) of rabbits' eyes during standard ultraviolet (UV) cross-linking with account to the area of corneal debridement. Forty two rabbits were studied sequentially. The following solutions of riboflavin were used for cornea saturation: IR - 0.1% isosmotic riboflavin, D - Dextralink (0.1% riboflavin with 20% dextran), R - 0.1% riboflavin with 1.0% hydroxypropylmethylcellulose (HPMC). Each solution was evaluated in 3 groups that differed in the diameter of corneal debridement: group 1 - Epi-Off 3 mm (IR-3, D-3, P-3), group 2 - Epi-Off 6 mm (IR-6, D-6, R-6), and group 3 - Epi-Off 9 mm (IR-9, D-9, R-9). Aqueous humour sampling (252 samples in total) was performed in 10-minute intervals within a 60 minute period. Riboflavin levels were measured by enzyme-linked immunoassay (ID-Vit microbiological test system; Immundiagnostik, Germany). Stable growth rates of riboflavin level in the AHAC (with maximum values reached at 30-40 min) were observed for solutions D and R, regardless of the variant of corneal debridement. Moreover, throughout the whole follow-up period and regardless of the area of corneal debridement, the solution D provided a relatively lower concentration of riboflavin in the AHAC as compared to the two other solutions. At 30 minutes, when the cornea was considered ready for UV irradiation, the riboflavin level in the AHAC ranged from 385±26.1 μg/l (D-9) to 665±28 μg/l (R-9). In groups IR-9, IR-6, P-6, IR-3, and P-3 riboflavin levels were found to be in the same range starting at 20 minutes. However, even a sufficient concentration of riboflavin in the cornea or AHAC cannot guarantee safe and effective UV cross-linking, since the removed epithelium limits the area of the stroma that can be saturated with riboflavin, while the area of UV exposure is 8-10 mm. Safe and efficient standard UV cross-linking may be performed only under sufficient saturation of the

  11. Association of Cross Linked C-Telopeptide II Collagen and Hyaluronic Acid with Knee Osteoarthritis Severity

    Directory of Open Access Journals (Sweden)

    John Butar Butar

    2013-12-01

    Full Text Available BACKGROUND: This study was carried out to investigate the association of Cross Linked C-Telopeptide Type I & II Collagen (CTX-I and II and hyaluronic acid (HA with knee osteoarthritis (OA severity. METHODS: Sixty menopause women with primary knee OA were enrolled in this study during their visits to the Outpatient Department. Patients with knee pain during weight bearing, active or passive range of motion, or tenderness with Kellgren-Lawrence (KL grade of more than I were included. Patients with injury, inflammatory and metabolic diseases were excluded. Patients were put in a 10-hour fasting prior to withdrawal of morning blood samples for examinations of HA, CTX-I, interleukin 1 beta (IL-1β, and high sensitivity C reactive protein (hs-CRP level. Second void morning urine specimens were taken for CTXII assessment. HA, CTX-I and II levels were measured by enzyme-linked immunosorbent assay. RESULTS: Sixty menopausal female patients were included in this study, 35 with KL grade II, 17 grade III, and 8 grade IV. Means of CTX-II were significantly different between subjects KL grade IV and III (p=0.021. Correlation of KL grade was significant with CTX-II (p=0.001, r=0.412 and HA (p=0.0411, r=0.269. KL grades were not significantly associated with CTX-I (p=0.8364, r=-0.0272; IL-1β (p=0.5773, r=0.0853 and hs-CRP (p=0.2625, r=0.1470. CONCLUSIONS: CTX-II and HA were associated with severity of knee OA, suggesting that CTX-II and HA can be used as marker for knee OA severity. KEYWORDS: CTX-II, hyaluronic acid, otestoarthritis, knee.

  12. Comparing Change in Anterior Curvature after Corneal Cross-Linking Using Scanning-Slit and Scheimpflug Technology.

    Science.gov (United States)

    Lang, Paul Z; Thulasi, Praneetha; Khandelwal, Sumitra S; Hafezi, Farhad; Randleman, J Bradley

    2018-05-02

    To evaluate the correlation between anterior axial curvature difference maps following corneal cross-linking (CXL) for progressive keratoconus obtained from Scheimpflug-based tomography and Placido-based topography. Between-devices reliability analysis of randomized clinical trial data METHODS: Corneal imaging was collected at a single center institution pre-operatively and at 3, 6, and 12 months post-operatively using Scheimpflug-based tomography (Pentacam, Oculus Inc., Lynnwood, WA) and Scanning-slit, Placido-based topography (Orbscan II, Bausch & Lomb, Rochester, NY) in patients with progressive keratoconus receiving standard protocol CXL (3mW/cm 2 for 30 minutes). Regularization index (RI), absolute maximum keratometry (K Max), and change in (ΔK Max) were compared between the two devices at each time point. 51 eyes from 36 patients were evaluated at all time points. values were significantly different at all time points [56.01±5.3D Scheimpflug vs. 55.04±5.1D scanning-slit pre-operatively (p=0.003); 54.58±5.3D Scheimpflug vs. 53.12±4.9D scanning-slit at 12 months (pdevices (r=0.90-0.93) at all time points. The devices were not significantly different at any time point for either ΔK Max or RI but were poorly correlated at all time points (r=0.41-0.53 for ΔK Max, r=0.29-0.48 for RI). At 12 months, 95% LOA was 7.51D for absolute, 8.61D for ΔK Max, and 19.86D for RI. Measurements using Scheimpflug and scanning-slit Placido-based technology are correlated but not interchangeable. Both devices appear reasonable for separately monitoring the cornea's response to CXL; however, caution should be used when comparing results obtained with one measuring technology to the other. Copyright © 2018 Elsevier Inc. All rights reserved.

  13. Corneal Laceration

    Medline Plus

    Full Text Available ... Tips & Prevention News Ask an Ophthalmologist Patient Stories Español Eye Health / Eye Health A-Z Corneal Laceration ... Laceration Treatment What Is Corneal Laceration? Leer en Español: ¿Qué es una laceración de la córnea? Written ...

  14. Corneal Transplantation

    DEFF Research Database (Denmark)

    Hjortdal, Jesper Østergaard

    with less risk of rejection episodes. Besides covering updated chapters on penetrating keratoplasty, and anterior and posterior lamellar procedures, this textbook also gives a thorough overview of the history of corneal transplantation and a detailed presentation of the microstructural components...... and to assist fellows and corneal surgeons in their advice and selection of patients for the best surgical procedure considering benefi ts and risks....

  15. Corneal cross-linking in a child with osteogenesis imperfecta syndrome and keratoconus

    Directory of Open Access Journals (Sweden)

    Sergio Kwitko

    2017-07-01

    Full Text Available Cross-linking (CXL is a well-established procedure in children with keratoconus (KC, but cases of CXL and osteogenesis imperfecta (OI have not been published in the literature, despite the association between physiopathology of these diseases. This is the first case, to the best of our knowledge, of a young girl with both OI and KC that underwent a CXL treatment. In this case, CXL was performed at 6-years-old prior to an expected progression, without complications and probably stopped further keratoconus progression.

  16. BIOCOMPATIBILITY AND TISSUE REGENERATING CAPACITY OF CROSS-LINKED DERMAL SHEEP COLLAGEN

    NARCIS (Netherlands)

    VANWACHEM, PB; VANLUYN, MJA; DAMINK, LHHO; DIJKSTRA, PJ; FEIJEN, J; NIEUWENHUIS, P

    The biocompatibility and tissue regenerating capacity of four crosslinked dermal sheep collagens (DSC) was studied. In vitro, the four DSC versions were found to be noncytotoxic or very low in cytoxicity. After subcutaneous implantation in rats, hexamethylenediisocyanate-crosslinked DSC (HDSC)

  17. Occlusal loading and cross-linking effects on dentin collagen degradation in physiological conditions.

    Science.gov (United States)

    Turco, Gianluca; Frassetto, Andrea; Fontanive, Luca; Mazzoni, Annalisa; Cadenaro, Milena; Di Lenarda, Roberto; Tay, Franklin R; Pashley, David H; Breschi, Lorenzo

    2016-02-01

    This study evaluated the ability of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) to improve the stability of demineralized dentin collagen matrices when subjected to mechanical cycling by means of Chewing Simulation (CS). Demineralized dentin disks were randomly assigned to four groups (N=4): (1) immersion in artificial saliva at 37°C for 30 days; (2) pre-treatment with 0.5 M EDC for 60 s, then stored as in Group 1; (3) CS challenge (50 N occlusal load, 30 s occlusal time plus 30 s with no load, for 30 days); (4) pre-treatment with 0.5 M EDC as in Group 2 and CS challenge as in Group 3. Collagen degradation was evaluated by sampling storage media for ICTP and CTX telopeptides. EDC treated specimens showed no significant telopeptides release, irrespective of the aging method. Cyclic stressing of EDC-untreated specimens caused significantly higher ICTP release at day 1, compared to static storage, while by days 3 and 4, the ICTP release in the cyclic group fell significantly below the static group, and then remained undetectable from 5 to 30 days. CTX release in the cyclic groups, on EDC-untreated control specimens was always lower than in the static group in days 1-4, and then fell to undetectable for 30 days. This study showed that chewing stresses applied to control untreated demineralized dentin increased degradation of collagen in terms of CTX release, while collagen crosslinking agents may prevent dentin collagen degradation, irrespective of simulated occlusal function. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Corneal Cross-Linking Has No Effect on Matrix Metalloproteinase 9 and 13 Levels During Fungal Keratitis on the Early Stage.

    Science.gov (United States)

    Kalkanci, Ayse; Bilgihan, Kamil; Ozdemir, Huseyin Baran; Yar Saglam, Atiye Seda; Karakurt, Funda; Erdogan, Merve

    2018-04-01

    The aim of our study was to investigate matrix metalloproteinases, MMP-9 and MMP-13 levels, in the rabbit model of Fusarium and Candida keratitis treated by corneal cross-linking (PACK-CXL). Rabbit corneas were inoculated with fungal inoculum for keratitis. Each group divided into four subgroups, including un-treated group, PACK-CXL group, voriconazole group and PACK-CXL plus voriconazole group. PACK-CXL was applied with 0.25% riboflavin in accelerated Dresden protocol, and 0.1% voriconazole drops were administered. All corneal buttons excised at tenth day after ophthalmological examination. Fungal cell counts and Scheiber scores were determined in all groups. Corneal tissue MMP mRNA levels were evaluated quantitative reverse transcriptase PCR. The difference in MMP-9 and MMP-13 levels at all groups was not statistically significant (p > 0.05). PACK-CXL with 0.25% riboflavin either alone or combined with antifungal drops was unable to provide decline in inflammatory findings in both macroscopic and microscopic levels similar to medical antifungal treatment.

  19. Corneal Laceration

    Medline Plus

    Full Text Available ... by something sharp flying into the eye. It can also be caused by something striking the eye ... If the corneal laceration is deep enough it can cause a full thickness laceration. This is when ...

  20. Corneal Laceration

    Medline Plus

    Full Text Available ... to Full Corneal Transplantation Nov 29, 2016 Follow The Academy Professionals: Education Guidelines News Multimedia Public & Patients: Contact Us About the Academy Jobs at the Academy Financial Relationships with Industry ...

  1. Ultra B2 - Promoção de ligações covalentes do colágeno corneal (Corneal cross-linking no tratamento de ceratocone: resultados preliminares Corneal Cross-linking for the treatment of keratoconus: preliminary results

    Directory of Open Access Journals (Sweden)

    Mirko R. Jankov II

    2008-12-01

    atingir diferença estatisticamente significante. Nenhum dos olhos perdeu linha de BSCVA, 12 mantiveram o BSCVA pré-operatório, 7 ganharam uma linha, 5 ganharam duas e 1 paciente ganhou três linhas de BSCVA. CONCLUSÕES: O tratamento com Ultra-B2 mostrou-se seguro (não apresentou perda de linha de visão corrigida e eficaz (manteve os parâmetros anatômicos e ópticos em estacionar a progressão da ectasia corneal. Houve redução, embora sem significância estatística, da curvatura corneal máxima, equivalente esférico e cilindro refrativo nos olhos com a córnea instável devida ao ceratocone.PURPOSE: To present early visual and keratometric results for corneal cross-linking with riboflavin and UV irradiation in patients with progressive keratoconus. METHODS: Twenty-five eyes of twenty patients (15 males and 5 females with a progressive keratoconus in the previous 6 months were followed. Unaided visual acuity (UVA, best spectacle corrected visual acuity (BSCVA, spherical equivalent (SEQ, manifest cylinder, and maximal corneal curvature (max K values were followed at 1, 3 and 6 months. All patients were submitted to corneal cross-linking using riboflavin (vitamin B2 as the photosensitizer and ultraviolet light (UV, wavelength 370 nm. Epithelium was removed with 20% alcohol, cornea was soaked with vitamin B2 for 15 min, and then irradiated with UV light for 30 min, after which a bandage contact lens (BCL was placed. RESULTS: UVA increased after one month (from 0.15 ± 0.15 to 0.23 ± 0.20, and went on increasing at 3 and 6 months, reaching statistical significance (p=0.025 e p=0.037, respectively. BSCVA increased from 0.41 ± 0.27 to 0.49 ± 0.29 at month six, without reaching statistical significance at any time point. Progression of keratoconus stopped in all patients, in contrast with progression in all of them in the six-month period prior to the surgery. Max K decreased by more than 2 D (from 53.02 ± 8.42 to 50.88 ± 6.05 D, SEQ less that 1 D (from -3.27 ± 4

  2. Corneal structure and transparency

    Science.gov (United States)

    Meek, Keith M.; Knupp, Carlo

    2015-01-01

    The corneal stroma plays several pivotal roles within the eye. Optically, it is the main refracting lens and thus has to combine almost perfect transmission of visible light with precise shape, in order to focus incoming light. Furthermore, mechanically it has to be extremely tough to protect the inner contents of the eye. These functions are governed by its structure at all hierarchical levels. The basic principles of corneal structure and transparency have been known for some time, but in recent years X-ray scattering and other methods have revealed that the details of this structure are far more complex than previously thought and that the intricacy of the arrangement of the collagenous lamellae provides the shape and the mechanical properties of the tissue. At the molecular level, modern technologies and theoretical modelling have started to explain exactly how the collagen fibrils are arranged within the stromal lamellae and how proteoglycans maintain this ultrastructure. In this review we describe the current state of knowledge about the three-dimensional stromal architecture at the microscopic level, and about the control mechanisms at the nanoscopic level that lead to optical transparency. PMID:26145225

  3. Cross-ancestry genome-wide association analysis of corneal thickness strengthens link between complex and Mendelian eye diseases

    NARCIS (Netherlands)

    Iglesias, A.I. (Adriana I.); A. Mishra (Aniket); V. Vitart (Veronique); Y. Bykhovskaya (Yelena); R. Höhn (René); H. Springelkamp (Henriët); G. Cuellar-Partida (Gabriel); P. Gharahkhani (Puya); Bailey, J.N.C. (Jessica N. Cooke); Willoughby, C.E. (Colin E.); X. Li (Xiaohui); S. Yazar (Seyhan); A. Nag (Abhishek); A.P. Khawaja (Anthony); O. Polasek (Ozren); D.S. Siscovick (David); Mitchell, P. (Paul); Y.C. Tham (Yih Chung); J.L. Haines (Jonathan); L.S. Kearns (Lisa S.); C. Hayward (Caroline); Shi, Y. (Yuan); Van Leeuwen, E.M. (Elisabeth M.); K.D. Taylor (Kent); Wang, J.J. (Jie Jin); E. Rochtchina (Elena); J. Attia (John); Scott, R. (Rodney); E.G. Holliday (Elizabeth); P.N. Baird (Paul); Xie, J. (Jing); Inouye, M. (Michael); Viswanathan, A. (Ananth); X. Sim (Xueling); P.W.M. Bonnemaijer (Pieter); J.I. Rotter (Jerome I.); Martin, N.G. (Nicholas G.); T. Zeller (Tanja); R.A. Mills (Richard); S.E. Staffieri (Sandra E.); Jonas, J.B. (Jost B.); Schmidtmann, I. (Irene); T. Boutin (Thibaud); Kang, J.H. (Jae H.); S.E.M. Lucas (Sionne E.M.); Wong, T.Y. (Tien Yin); Beutel, M.E. (Manfred E.); Wilson, J.F. (James F.); R.R. Allingham (R Rand); M.H. Brilliant (Murray H.); D.L. Budenz (Donald L.); W.G. Christen (William G.); J. Fingert (John); D.S. Friedman (David); Gaasterland, D. (Douglas); T. Gaasterland (Terry); M.A. Hauser (Michael); P. Kraft (Peter); Lee, R.K. (Richard K.); P.A. Lichter (Paul A.); Liu, Y. (Yutao); S.J. Loomis (Stephanie J.); S.E. Moroi (Sayoko); M.A. Pericak-Vance (Margaret); A. Realini (Anthony); Richards, J.E. (Julia E.); J.S. Schuman (Joel S.); W.K. Scott (William); K. Singh (Kuldev); A.J. Sit (Arthur J.); D. Vollrath (Douglas); R.N. Weinreb (Robert N.); G. Wollstein (Gadi); D.J. Zack (Donald); K. Zhang (Kang); Donnelly, P. (Peter); I.E. Barroso (Inês); Blackwell, J.M. (Jenefer M.); E. Bramon (Elvira); M.A. Brown (Matthew); J.P. Casas (Juan); A. Corvin (Aiden); Deloukas, P. (Panos); A. Duncanson (Audrey); Jankowski, J. (Janusz); H.S. Markus (Hugh); J. Mathew (Joseph); C.N.A. Palmer (Colin); R. Plomin (Robert); A. Rautanen (Anna); S.J. Sawcer (Stephen); R.C. Trembath (Richard); Wood, N.W. (Nicholas W.); C.C.A. Spencer (Chris C.); G. Band (Gavin); C. Bellenguez (Céline); Freeman, C. (Colin); F.A. Hellenthal; E. Giannoulatou (Eleni); M. Pirinen (Matti); R. Pearson (Ruth); A. Strange (Amy); Z. Su (Zhan); D. Vukcevic (Damjan); Langford, C. (Cordelia); Hunt, S.E. (Sarah E.); T. Edkins (Ted); R. Gwilliam (Rhian); H. Blackburn (Hannah); S. Bumpstead (Suzannah); S. Dronov (Serge); M. Gillman (Matthew); E. Gray (Emma); N. Hammond (Naomi); A. Jayakumar (Alagurevathi); O.T. McCann (Owen); J. Liddle (Jennifer); S.C. Potter (Simon); Ravindrarajah, R. (Radhi); Ricketts, M. (Michelle); P. Waller (Patrick); P. Weston (Paul); S. Widaa (Sara); Whittaker, P. (Pamela); A.G. Uitterlinden (André); E.N. Vithana (Eranga); P.J. Foster (Paul); P.G. Hysi (Pirro); Hewitt, A.W. (Alex W.); C.C. Khor; L.R. Pasquale (Louis); Montgomery, G.W. (Grant W.); C.C.W. Klaver (Caroline); T. Aung (Tin); A.F.H. Pfeiffer (Andreas); D.A. Mackey (David); C.J. Hammond (Christopher); Cheng, C.-Y. (Ching-Yu); J.E. Craig (Jamie); Y.S. Rabinowitz (Yaron); J.L. Wiggs (Janey L.); K.P. Burdon (Kathryn); C.M. van Duijn (Cornelia); MacGregor, S. (Stuart)

    2018-01-01

    textabstractCentral corneal thickness (CCT) is a highly heritable trait associated with complex eye diseases such as keratoconus and glaucoma. We perform a genome-wide association meta-analysis of CCT and identify 19 novel regions. In addition to adding support for known connective tissue-related

  4. Preparation and characterization of malonic acid cross-linked chitosan and collagen 3D scaffolds: an approach on non-covalent interactions.

    Science.gov (United States)

    Mitra, Tapas; Sailakshmi, G; Gnanamani, A; Mandal, A B

    2012-05-01

    The present study emphasizes the influence of non-covalent interactions on the mechanical and thermal properties of the scaffolds of chitosan/collagen origin. Malonic acid (MA), a bifuncitonal diacid was chosen to offer non-covalent cross-linking. Three dimensional scaffolds was prepared using chitosan at 1.0% (w/v) and MA at 0.2% (w/v), similarly collagen 0.5% (w/v) and MA 0.2% (w/v) and characterized. Results on FT-IR, TGA, DSC, SEM and mechanical properties (tensile strength, stiffness, Young's modulus, etc.) assessment demonstrated the existence of non-covalent interaction between MA and chitosan/collagen, which offered flexibility and high strength to the scaffolds suitable for tissue engineering research. Studies using NIH 3T3 fibroblast cells suggested biocompatibility nature of the scaffolds. Docking simulation study further supports the intermolecular hydrogen bonding interactions between MA and chitosan/collagen.

  5. Effect of pore size and cross-linking of a novel collagen-elastin dermal substitute on wound healing.

    Science.gov (United States)

    Boekema, Bouke K H L; Vlig, Marcel; Olde Damink, Leon; Middelkoop, Esther; Eummelen, Lizette; Bühren, Anne V; Ulrich, Magda M W

    2014-02-01

    Collagen-elastin (CE) scaffolds are frequently used for dermal replacement in the treatment of full-thickness skin defects such as burn wounds. But little is known about the optimal pore size and level of cross-linking. Different formulations of dermal substitutes with unidirectional pores were tested in porcine full-thickness wounds in combination with autologous split skin mesh grafts (SSG). Effect on wound healing was evaluated both macro- and microscopically. CE scaffolds with a pore size of 80 or 100 μm resulted in good wound healing after one-stage grafting. Application of scaffolds with a larger average pore size (120 μm) resulted in more myofibroblasts and more foreign body giant cells (FBGC). Moderate crosslinking impaired wound healing as it resulted in more wound contraction, more FBGC and increased epidermal thickness compared to no cross-linking. In addition, take rate and redness were negatively affected compared to SSG only. Vascularization and the number of myofibroblasts were not affected by cross-linking. Surprisingly, stability of cross-linked scaffolds was not increased in the wound environment, in contrast to in vitro results. Cross-linking reduced the proliferation of fibroblasts in vitro, which might explain the reduced clinical outcome. The non-cross-linked CE substitute with unidirectional pores allowed one-stage grafting of SSG, resulting in good wound healing. In addition, only a very mild foreign body reaction was observed. Cross-linking of CE scaffolds negatively affected wound healing on several important parameters. The optimal non-cross-linked CE substitute is a promising candidate for future clinical evaluation.

  6. Confocal Raman mapping of collagen cross-link and crystallinity of human dentin-enamel junction

    Science.gov (United States)

    Slimani, Amel; Nouioua, Fares; Desoutter, Alban; Levallois, Bernard; Cuisinier, Frédéric J. G.; Tassery, Hervé; Terrer, Elodie; Salehi, Hamideh

    2017-08-01

    The separation zone between enamel and dentin [dentin-enamel junction (DEJ)] with different properties in biomechanical composition has an important role in preventing crack propagation from enamel to dentin. The understanding of the chemical structure (inorganic and organic components), physical properties, and chemical composition of the human DEJ could benefit biomimetic materials in dentistry. Spatial distribution of calcium phosphate crystallinity and the collagen crosslinks near DEJ were studied using confocal Raman microscopy and calculated by different methods. To obtain collagen crosslinking, the ratio of two peaks 1660 cm-1 over 1690 cm-1 (amide I bands) is calculated. For crystallinity, the inverse full-width at half maximum of phosphate peak at 960 cm-1, and the ratio of two Raman peaks of phosphate at 960/950 cm-1 is provided. In conclusion, the study of chemical and physical properties of DEJ provides many benefits in the biomaterial field to improve the synthesis of dental materials in respect to the natural properties of human teeth. Confocal Raman microscopy as a powerful tool provides the molecular structure to identify the changes along DEJ and can be expanded for other mineralized tissues.

  7. Visual rehabilitation in low-moderate keratoconus:intracorneal ring segment implantation followed by same-day topography-guided photorefractive keratectomy and collagen cross linking

    Directory of Open Access Journals (Sweden)

    Ferial M. Zeraid

    2014-10-01

    Full Text Available AIM:To present the results of same-day topography-guided photorefractive keratectomy (TG-PRK and corneal collagen crosslinking (CXL after previous intrastromal corneal ring segment (ISCR implantation for keratoconus.METHODS:An experimental clinical study on twenty-one eyes of 19 patients aged 27.1±6.6y (range 19-43y, with low to moderate keratoconus who were selected to undergo customized TG-PRK immediately followed by same-day CXL, 9mo after ISCR implantation in a university ophthalmology clinic. Refraction, uncorrected distance visual acuities (UDVA and corrected distance visual acuities (CDVA, keratometry (K values, central corneal thickness (CCT and coma were assessed 3mo after TG-PRK and CXL.RESULTS:After TG-PRK/CXL:the mean UDVA (logMAR improved significantly from 0.66±0.41 to 0.20±0.25 (P<0.05; Kflat value decreased from:48.44±3.66 D to 43.71±1.95 D; Ksteep value decreased from 45.61±2.40 D to 41.56±2.05 D; Kaverage also decreased from 47.00±2.66 D to 42.42±2.07 D (P<0.05 for all. The mean sphere and cylinder decreased significantly post-surgery from, -3.10±2.99 D to -0.11±0.93 D and from -3.68±1.53 to -1.11±0.75 D respectively, while the CDVA, CCT and coma showed no significant changes. Compared to post-ISCR, significant reductions (P<0.05 or all in all K values, sphere and cylinder were observed after TG-PRK/CXL.CONCLUSION:Same-day combined topography-guided PRK and corneal crosslinking following placement of ISCR is a safe and potentially effective option in treating low-moderate keratoconus. It significantly improves all visual acuity, reduced keratometry, sphere and astigmatism, but causes no change in central corneal thickness and coma.

  8. Corneal markers of diabetic neuropathy.

    Science.gov (United States)

    Pritchard, Nicola; Edwards, Katie; Shahidi, Ayda M; Sampson, Geoff P; Russell, Anthony W; Malik, Rayaz A; Efron, Nathan

    2011-01-01

    Diabetic neuropathy is a significant clinical problem that currently has no effective therapy, and in advanced cases, leads to foot ulceration and lower limb amputation. The accurate detection, characterization and quantification of this condition are important in order to define at-risk patients, anticipate deterioration, monitor progression, and assess new therapies. This review evaluates novel corneal methods of assessing diabetic neuropathy. Two new noninvasive corneal markers have emerged, and in cross-sectional studies have demonstrated their ability to stratify the severity of this disease. Corneal confocal microscopy allows quantification of corneal nerve parameters and noncontact corneal esthesiometry, the functional correlate of corneal structure, assesses the sensitivity of the cornea. Both these techniques are quick to perform, produce little or no discomfort for the patient, and are suitable for clinical settings. Each has advantages and disadvantages over traditional techniques for assessing diabetic neuropathy. Application of these new corneal markers for longitudinal evaluation of diabetic neuropathy has the potential to reduce dependence on more invasive, costly, and time-consuming assessments, such as skin biopsy.

  9. Cross-ancestry genome-wide association analysis of corneal thickness strengthens link between complex and Mendelian eye diseases

    OpenAIRE

    Iglesias, Adriana I; Mishra, Aniket; Vitart, Veronique; Bykhovskaya, Yelena; Höhn, René; Springelkamp, Henriët; Cuellar-Partida, Gabriel; Gharahkhani, Puya; Bailey, Jessica N Cooke; Willoughby, Colin E; Li, Xiaohui; Yazar, Seyhan; Nag, Abhishek; Khawaja, Anthony P.; Polasek, Ozren

    2018-01-01

    Central corneal thickness (CCT) is a highly heritable trait associated with complex eye diseases such as keratoconus and glaucoma. We perform a genome-wide association meta-analysis of CCT and identify 19 novel regions. Pathway analyses uncover new, as well as supported the role of connective tissue-related, pathways. Remarkably, >20% of the CCT-loci are near or within Mendelian disorder genes. These included FBN1, ADAMTS2 and TGFB2 which associate with connective tissue disorders (Marfan,...

  10. Corneal topography

    DEFF Research Database (Denmark)

    Andersen, J.; Koch-Jensen, P.; Østerby, Ole

    1993-01-01

    The central corneal zone is depicted on keratoscope photographs using a small target aperture and a large object distance. Information on the peripheral area is included by employing a hemispherical target with a dense circular and radial pattern. On a 16 mm (R = 8 mm) reference steel sphere the ...

  11. Cross-Linking GPVI-Fc by Anti-Fc Antibodies Potentiates Its Inhibition of Atherosclerotic Plaque- and Collagen-Induced Platelet Activation

    Directory of Open Access Journals (Sweden)

    Janina Jamasbi, RPh

    2016-04-01

    Full Text Available To enhance the antithrombotic properties of recombinant glycoprotein VI fragment crystallizable (GPVI-Fc, the authors incubated GPVI-Fc with anti-human Fc antibodies to cross-link the Fc tails of GPVI-Fc. Cross-linking potentiated the inhibition of human plaque- and collagen-induced platelet aggregation by GPVI-Fc under static and flow conditions without increasing bleeding time in vitro. Cross-linking with anti-human-Fc Fab2 was even superior to anti-human-Fc immunoglobulin G (IgG. Advanced optical imaging revealed a continuous sheath-like coverage of collagen fibers by cross-linked GPVI-Fc complexes. Cross-linking of GPVI into oligomeric complexes provides a new, highly effective, and probably safe antithrombotic treatment as it suppresses platelet GPVI-plaque interaction selectively at the site of acute atherothrombosis.

  12. Applications of corneal topography and tomography: a review.

    Science.gov (United States)

    Fan, Rachel; Chan, Tommy Cy; Prakash, Gaurav; Jhanji, Vishal

    2018-03-01

    Corneal imaging is essential for diagnosing and management of a wide variety of ocular diseases. Corneal topography is used to characterize the shape of the cornea, specifically, the anterior surface of the cornea. Most corneal topographical systems are based on Placido disc that analyse rings that are reflected off the corneal surface. The posterior corneal surface cannot be characterized using Placido disc technology. Imaging of the posterior corneal surface is useful for diagnosis of corneal ectasia. Unlike corneal topographers, tomographers generate a three-dimensional recreation of the anterior segment and provide information about the corneal thickness. Scheimpflug imaging is one of the most commonly used techniques for corneal tomography. The cross-sectional images generated by a rotating Scheimpflug camera are used to locate the anterior and posterior corneal surfaces. The clinical uses of corneal topography include, diagnosis of corneal ectasia, assessment of corneal astigmatism, and refractive surgery planning. This review will discuss the applications of corneal topography and tomography in clinical practice. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

  13. Technical advances in the sectioning of dental tissue and of on-section cross-linked collagen detection in mineralized teeth.

    Science.gov (United States)

    Singhrao, Sim K; Sloan, Alastair J; Smith, Emma L; Archer, Charles W

    2010-08-01

    Immunohistochemical detection of cross-linked fibrillar collagens in mineralized tissues is much desired for exploring the mechanisms of biomineralization in health and disease. Mineralized teeth are impossible to section when embedded in conventional media, thus limiting on-section characterization of matrix proteins by immunohistochemistry. We hypothesized that by using an especially formulated acrylic resin suitable for mineralized dental tissues, not only sectioning of teeth would be possible, but also our recently developed immunofluorescence labeling technique would be amenable to fully calcified tissues for characterization of dentinal fibrillar collagens, which remains elusive. The hypothesis was tested on fixed rodent teeth embedded in Technovit 9100 New. It was possible to cut thin (1 mum) sections of mineralized teeth, and immunofluorescence characterization of cross-linked type I fibrillar collagen was selected due to its abundance in dentine. Decalcified samples of teeth embedded in paraffin wax were also used to compare immunolabeling from either method using the same immunoreagents in equivalent concentrations. In the decalcified tissue sections, type I collagen labeling in the dentine along the tubules was "patchy" and the signal in the predentine was very weak. However, enhanced signal in mineralized samples with type I collagen was detected not only in the predentine but also at the limit between intertubular dentine, within the elements of the enamel organ and subgingival stroma. This report offers advances in sectioning mineralized dental tissues and allows the application of immunofluorescence not only for on-section protein detection but importantly for detecting cross-linked fibrous collagens in both soft and mineralized tissue sections.

  14. Construction of a human corneal stromal equivalent with non-transfected human corneal stromal cells and acellular porcine corneal stromata.

    Science.gov (United States)

    Diao, Jin-Mei; Pang, Xin; Qiu, Yue; Miao, Ying; Yu, Miao-Miao; Fan, Ting-Jun

    2015-03-01

    A tissue-engineered human corneal stroma (TE-HCS) has been developed as a promising equivalent to the native corneal stroma for replacement therapy. However, there is still a crucial need to improve the current approaches to render the TE-HCS equivalent more favorable for clinical applications. At the present study, we constructed a TE-HCS by incubating non-transfected human corneal stromal (HCS) cells in an acellular porcine corneal stromata (aPCS) scaffold in 20% fetal bovine serum supplemented DMEM/F12 (1:1) medium at 37 °C with 5% CO2in vitro. After 3 days of incubation, the constructed TE-HCS had a suitable tensile strength for transplantation, and a transparency that is comparable to native cornea. The TE-HCS had a normal histological structure which contained regularly aligned collagen fibers and differentiated HCS cells with positive expression of marker and functional proteins, mimicking a native HCS. After transplantation into rabbit models, the TE-HCS reconstructed normal corneal stroma in vivo and function well in maintaining corneal clarity and thickness, indicating that the completely biological TE-HCS could be used as a HCS equivalent. The constructed TE-HCS has promising potentials in regenerative medicine and treatment of diseases caused by corneal stromal disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Gum arabic modified Fe3O4 nanoparticles cross linked with collagen for isolation of bacteria

    Directory of Open Access Journals (Sweden)

    Chittor Raghuraman

    2010-12-01

    Full Text Available Abstract Background Multifunctional magnetic nanoparticles are important class of materials in the field of nanobiotechnology, as it is an emerging area of research for material science and molecular biology researchers. One of the various methods to obtain multifunctional nanomaterials, molecular functionalization by attaching organic functional groups to nanomagnetic materials is an important technique. Recently, functionalized magnetic nanoparticles have been demonstrated to be useful in isolation/detection of dangerous pathogens (bacteria/viruses for human life. Iron (Fe based material especially FePt is used in the isolation of ultralow concentrations (2 cfu/ml of bacteria in less time and it has been demonstrated that van-FePt may be used as an alternative fast detection technique with respect to conventional polymerase chain reaction (PCR method. However, still further improved demonstrations are necessary with interest to biocompatibility and green chemistry. Herein, we report the synthesis of Fe3O4 nanoparticles by template medication and its application for the detection/isolation of S. aureus bacteria. Results The reduction of anhydrous Iron chloride (FeCl3 in presence of sodium borohydride and water soluble polyelectrolyte (polydiallyldimethyl ammonium chloride, PDADMAC produces black precipitates. The X-ray diffraction (XRD, XPS and TEM analysis of the precipitates dried at 373 K demonstrated the formation of nanocrystalline Fe3O4. Moreover, scanning electron microscopy (SEM showed isolated staphylococcous aureus (S. aureus bacteria at ultralow concentrations using collagen coated gum arabic modified iron oxide nanoparticles (CCGAMION. Conclusion We are able to synthesize nanocrystalline Fe3O4 and CCGAMION was able to isolate S. aureus bacteria at 8-10 cfu (colony forming units/ml within ~3 minutes.

  16. Serum cross-linked n-telopeptides of type 1 collagen (NTx in patients with solid tumors

    Directory of Open Access Journals (Sweden)

    Fernando Jablonka

    Full Text Available CONTEXT AND OBJECTIVE: Cross-linked N-telopeptides of type I collagen (NTx increase in concentration in situations in which bone resorption is increased, such as osteoporosis and bone metastasis (BM. We aimed to evaluate the serum concentrations of NTx in a sample of patients with several types of solid tumors. DESIGN AND SETTING: Cross-sectional analytical study with a control group in a tertiary public hospital. METHODS: We performed the quantitative enzyme-linked immunosorbent assay (ELISA on serum NTx levels in 19 subjects without a history of cancer and 62 patients with various solid tumors who had been referred for a bone scan. Three experienced analysts read all bone scans. RESULTS: The serum NTx levels in patients with cancer and BM, with cancer but without BM and without cancer were 46.77 ± 2.58, 32.85 ± 2.05 and 22.32 ± 2.90 respectively (P < 0.0001. We did not find any significant correlations of serum NTx with age, gender, history of bone pain, tumor type and bone alkaline phosphatase levels. We found a significant correlation between serum NTx and alkaline phosphatase levels (R² = 0.08; P = 0.022. CONCLUSIONS: Serum NTx levels are significantly higher in patients with solid tumors and bone metastases than they are in patients without bone metastases and in normal controls.

  17. TGFβ affects collagen cross-linking independent of chondrocyte phenotype but strongly depending on physical environment

    NARCIS (Netherlands)

    Bastiaansen-Jenniskens, Y.M.; Koevoet, W.; Bart, A.C.W. de; Zuurmond, A.-M.; Bank, R.A.; Verhaar, J.A.N.; Groot, J. de; Osch, G.J.V.M. van

    2008-01-01

    Transforming growth factor beta (TGFβ) is often used in cartilage tissue engineering to increase matrix formation by cells with various phenotypes. However, adverse effects of TGFβ, such as extensive cross-linking in cultured fibroblasts, have also been reported. Our goal was to study effects of

  18. Pirfenidone nanoparticles improve corneal wound healing and prevent scarring following alkali burn.

    Directory of Open Access Journals (Sweden)

    Sushovan Chowdhury

    Full Text Available To evaluate the effects of pirfenidone nanoparticles on corneal re-epithelialization and scarring, major clinical challenges after alkali burn.Effect of pirfenidone on collagen I and α-smooth muscle actin (α-SMA synthesis by TGFβ induced primary corneal fibroblast cells was evaluated by immunoblotting and immunocytochemistry. Pirfenidone loaded poly (lactide-co-glycolide (PLGA nanoparticles were prepared, characterized and their cellular entry was examined in primary corneal fibroblast cells by fluorescence microscopy. Alkali burn was induced in one eye of Sprague Dawley rats followed by daily topical treatment with free pirfenidone, pirfenidone nanoparticles or vehicle. Corneal re-epithelialization was assessed daily by flourescein dye test; absence of stained area indicated complete re-epithelialization and the time for complete re-epithelialization was determined. Corneal haze was assessed daily for 7 days under slit lamp microscope and graded using a standard method. After 7 days, collagen I deposition in the superficial layer of cornea was examined by immunohistochemistry.Pirfenidone prevented (P<0.05 increase in TGF β induced collagen I and α-SMA synthesis by corneal fibroblasts in a dose dependent manner. Pirfenidone could be loaded successfully within PLGA nanoparticles, which entered the corneal fibroblasts within 5 minutes. Pirfenidone nanoparticles but not free pirfenidone significantly (P<0.05 reduced collagen I level, corneal haze and the time for corneal re-epithelialization following alkali burn.Pirfenidone decreases collagen synthesis and prevents myofibroblast formation. Pirfenidone nanoparticles improve corneal wound healing and prevent fibrosis. Pirfenidone nanoparticles are of potential value in treating corneal chemical burns and other corneal fibrotic diseases.

  19. 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.

  20. A Comparison of Different Corneal Iontophoresis Protocols for Promoting Transepithelial Riboflavin Penetration.

    Science.gov (United States)

    Gore, Daniel M; O'Brart, David P; French, Paul; Dunsby, Chris; Allan, Bruce D

    2015-12-01

    To measure corneal riboflavin penetration using different transepithelial iontophoresis protocols. Freshly enucleated rabbit eyes were divided into nine treatment groups of 4 eyes. One group, in which 0.1% wt/vol riboflavin was applied for 30 minutes without iontophoresis after corneal epithelial debridement, acted as a control. The remaining groups were treated with an intact epithelium using different riboflavin formulations and varying iontophoresis current, soak, and rinse times. After riboflavin application, eyes were snap frozen in liquid nitrogen. Corneal cross sections 35 μm thick were then imaged immediately by two-photon fluorescence microscopy, using image processing software to quantify stromal riboflavin concentration at different corneal depths. In the epithelium-on iontophoresis treatment groups, greater stromal riboflavin penetration was achieved with higher-concentration riboflavin solutions, greater iontophoresis dosage, and longer solution contact times. A protocol utilizing 0.25% wt/vol riboflavin with benzalkonium chloride (BAC) 0.01% and two cycles of applied current and subsequent soaking (1 mA 5 minutes, soak 5 minutes; 0.5 mA 5 minutes, soak 5 minutes) achieved similar stromal riboflavin penetration to epithelium-off controls. The best-performing non-BAC-containing protocol produced stromal riboflavin penetration approximately 60% that of epithelium-off controls. Riboflavin solutions containing saline resulted in minimal stromal penetration. Riboflavin loading within the epithelium was equivalent to or higher than that in the subjacent stroma, despite rinsing the ocular surface with balanced salt solution. Modified iontophoresis protocols can significantly improve transepithelial riboflavin penetration in experimental corneal collagen cross-linking.

  1. Comparison of the Early Clinical Outcomes between Combined Small-Incision Lenticule Extraction and Collagen Cross-Linking versus SMILE for Myopia.

    Science.gov (United States)

    Ng, Alex L K; Chan, Tommy C Y; Cheng, George P M; Jhanji, Vishal; Ye, Cong; Woo, Victor C P; Lai, Jimmy S M

    2016-01-01

    Background. To compare the early outcome of combined SMILE and collagen crosslinking (SMILE Xtra) with SMILE. Method. Prospective, comparative interventional study of 21 eyes receiving SMILE Xtra using a low energy protocol and 32 control eyes receiving SMILE only. The outcomes were compared at 1, 3, and 6 months postoperatively. Results. Both groups had myopia with spherical equivalent refraction (SEQ) > 4.00 D. The SMILE Xtra group had thinner preoperative central corneal thickness and residual stromal bed thickness (p line in corrected distance visual acuity. The safety index was 0.96 ± 0.06 and 1.00 ± 0.00 in SMILE Xtra and control, respectively (p SMILE Xtra and +0.03 ± 0.25 D for control (p = 0.021). The efficacy index was 0.88 ± 0.13 and 0.97 ± 0.06, respectively (p = 0.005). Conclusion. SMILE Xtra had good overall safety profile and predictability at 6 months. However, when compared with control, the safety index and efficacy index were statistically significantly lower in the early postoperative period.

  2. Comparison of the Early Clinical Outcomes between Combined Small-Incision Lenticule Extraction and Collagen Cross-Linking versus SMILE for Myopia

    Directory of Open Access Journals (Sweden)

    Alex L. K. Ng

    2016-01-01

    Full Text Available Background. To compare the early outcome of combined SMILE and collagen crosslinking (SMILE Xtra with SMILE. Method. Prospective, comparative interventional study of 21 eyes receiving SMILE Xtra using a low energy protocol and 32 control eyes receiving SMILE only. The outcomes were compared at 1, 3, and 6 months postoperatively. Results. Both groups had myopia with spherical equivalent refraction (SEQ > 4.00 D. The SMILE Xtra group had thinner preoperative central corneal thickness and residual stromal bed thickness (p<0.021. At 6 months, no eyes lost more than 1 line in corrected distance visual acuity. The safety index was 0.96±0.06 and 1.00±0.00 in SMILE Xtra and control, respectively (p<0.001. 89% and 94% of eyes were within ±0.50 D of target refraction, respectively, with the mean error in SEQ correction being -0.17±0.26 D for SMILE Xtra and +0.03±0.25 D for control (p=0.021. The efficacy index was 0.88±0.13 and 0.97±0.06, respectively (p=0.005. Conclusion. SMILE Xtra had good overall safety profile and predictability at 6 months. However, when compared with control, the safety index and efficacy index were statistically significantly lower in the early postoperative period.

  3. Applications of biomaterials in corneal wound healing

    Directory of Open Access Journals (Sweden)

    I-Lun Tsai

    2015-04-01

    Full Text Available Disease affecting the cornea is a common cause of blindness worldwide. To date, the amniotic membrane (AM is the most widely used clinical method for cornea regeneration. However, donor-dependent differences in the AM may result in variable clinical outcomes. To overcome this issue, biomaterials are currently under investigation for corneal regeneration in vitro and in vivo. In this article, we highlight the recent advances in hydrogels, bioengineered prosthetic devices, contact lenses, and drug delivery systems for corneal regeneration. In clinical studies, the therapeutic effects of biomaterials, including fibrin and collagen-based hydrogels and silicone contact lenses, have been demonstrated in damaged cornea. The combination of cells and biomaterials may provide potential treatment in corneal wound healing in the future.

  4. Collagen turnover after tibial fractures

    DEFF Research Database (Denmark)

    Joerring, S; Krogsgaard, M; Wilbek, H

    1994-01-01

    Collagen turnover after tibial fractures was examined in 16 patients with fracture of the tibial diaphysis and in 8 patients with fracture in the tibial condyle area by measuring sequential changes in serological markers of turnover of types I and III collagen for up to 26 weeks after fracture....... The markers were the carboxy-terminal extension peptide of type I procollagen (PICP), the amino-terminal extension peptide of type III procollagen (PIIINP), and the pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (ICTP). The latter is a new serum marker of degradation of type I...... collagen. A group comparison showed characteristic sequential changes in the turnover of types I and III collagen in fractures of the tibial diaphysis and tibial condyles. The turnover of type III collagen reached a maximum after 2 weeks in both groups. The synthesis of type I collagen reached a maximum...

  5. Collagenous sprue

    DEFF Research Database (Denmark)

    Soendergaard, Christoffer; Riis, Lene Buhl; Nielsen, Ole Haagen

    2014-01-01

    Collagenous sprue is a rare clinicopathological condition of the small bowel. It is characterised by abnormal subepithelial collagen deposition and is typically associated with malabsorption, diarrhoea and weight loss. The clinical features of collagenous sprue often resemble those of coeliac...... disease and together with frequent histological findings like mucosal thinning and intraepithelial lymphocytosis the diagnosis may be hard to reach without awareness of this condition. While coeliac disease is treated using gluten restriction, collagenous sprue is, however, not improved...... by this intervention. In cases of diet-refractory 'coeliac disease' it is therefore essential to consider collagenous sprue to initiate treatment at an early stage to prevent the fibrotic progression. Here, we report a case of a 78-year-old man with collagenous sprue and present the clinical and histological...

  6. Equine corneal stromal abscesses

    DEFF Research Database (Denmark)

    Henriksen, M. D. L.; Andersen, P. H.; Plummer, C. E.

    2013-01-01

    The last 30 years have seen many changes in the understanding of the pathogenesis and treatment of equine corneal stromal abscesses (SAs). Stromal abscesses were previously considered an eye problem related to corneal bacterial infection, equine recurrent uveitis, corneal microtrauma and corneal....... Medical and surgical treatments are now directed towards elimination of fungal and bacterial infections, reduction and replacement of diseased corneal stroma, and suppression of iridocyclitis. If the abscess and anterior uveitis do not respond satisfactorily to medical therapy, full thickness or split...

  7. Corneal surface reconstruction - a short review

    Directory of Open Access Journals (Sweden)

    Madhavan H N

    2009-01-01

    Full Text Available Cornea is the clear, dome-shaped surface that covers the front of the eye and when damage due to burns or injury and several other diseases, stem cells residing in its rim called "limbus" are stimulated to multiply to support growth of new epithelial cells over its surface. If this ready source of stem cells is damaged or destroyed the natural repair is not possible and such a condition is known as corneal limbal stem cell deficiency (CLSCD disease. Stem cell transplant helps such persons to regenerate the corneal surface. Human corneal limbal stem cell transplantation is at present an established procedure with reasonable good clinical outcome particularly when autologous limbal epithelial tissue from a fellow unaffected eye is used. 1, 2 A major concern related to the autograft is the possibility of CLSCD at the donor site, 3 techniques that allowed the expansion of a small limbal biopsy in the laboratory using cell cultures that could be then transplanted to the affected eye have been developed ,4, 5 Human amniotic membrane (HAM is used as a scaffold for both culturing the human limbal epithelial cells and for ocular surface reconstruction with the cultured limbal epithelial cells. 4-7 However, researchers have used alternative scaffolds like collagen 8, fibrin gel 9 and cross-linked gel of fibronectin and fibrin. 10 All these are biological materials and also need for animal 3T3 feeder layer for stem cell cultures. The properties of HAM are unique including antiadhesive effects, bacteriostatic effects, wound protection, pain reduction, and improvement of epithelialization and characteristically lacking imunogenicity. The use of amniotic membrane transplantation (AMT to treat ocular surface abnormalities was first reported by Graziella Pellegrini, chief of stem cell laboratory at Giovanni Paolo Hospital in Venice, Italy, who was the first to demonstrate the limbal stem cell transplant in 1997. Amniotic membrane has been successfully used in

  8. Ultra B2 - Promoção de ligações covalentes do colágeno corneal (Corneal cross-linking) no tratamento de ceratocone: resultados preliminares

    OpenAIRE

    Jankov, Mirko R; Hafezi, Farhad; Beko, Maja; Ignjatovic, Zora; Djurovic, Branislav; Markovic, Vujica; Schor, Paulo

    2008-01-01

    OBJETIVO: Apresentar os resultados visuais e ceratométricos, seis meses após tratamento foto-terapêutico com luz ultravioleta (UV) e vitamina B2 (Ultra B2), em pacientes com ceratocone progressivo. MÉTODOS: Vinte e cinco olhos de 20 pacientes (15 homens e 5 mulheres) com ceratocone progressivo, determinado pelo aumento de curvatura em exames seriados de topografia corneal, nos últimos seis meses foram avaliados. Acuidade visual não corrigida (UVA), acuidade visual melhor corrigida com óculos ...

  9. Clinical evaluation of the Serum CrossLaps One Step ELISA, a new assay measuring the serum concentration of bone-derived degradation products of type I collagen C-telopeptides

    DEFF Research Database (Denmark)

    Christgau, S; Rosenquist, C; Alexandersen, P

    1998-01-01

    The Serum CrossLaps One Step ELISA is a sandwich assay using two monoclonal antibodies specific for a beta-aspartate form of the epitope EKAHDGGR derived from the carboxy-terminal telopeptide region of type I collagen alpha1-chain. Our objective was to assess the clinical value of the Serum Cross...

  10. [Collagen nephritis].

    Science.gov (United States)

    Lago, N R; Bulos, M J; Monserrat, A J

    1997-01-01

    Fibrillar collagen in the glomeruli is considered specific of the nail-patella syndrome. A new nephropathy with diffuse intraglomerular deposition of type III collagen without nail and skeletal abnormalities has been described. We report the case of a 26-year-old woman who presented persistent proteinuria, hematuria, deafness without nail and skeletal abnormalities. The renal biopsy showed focal and segmental glomerulosclerosis by light microscopy. The electron microscopy revealed the presence of massive fibrillar collagen within the mesangial matriz and the basement membrane. This is the first patient reported in our country. We emphasize the usefulness of electron microscopy in the study of glomerular diseases.

  11. Building blocks of Collagen based biomaterial devices

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Building blocks of Collagen based biomaterial devices. Collagen as a protein. Collagen in tissues and organs. Stabilizing and cross linking agents. Immunogenicity. Hosts (drugs). Controlled release mechanisms of hosts. Biodegradability, workability into devices ...

  12. Effect of Cycloplegia on Corneal Biometrics and Refractive State.

    Science.gov (United States)

    Bagheri, Abbas; Feizi, Mohadeseh; Shafii, Aliakbar; Faramarzi, Amir; Tavakoli, Mehdi; Yazdani, Shahin

    2018-01-01

    To determine changes in refractive state and corneal parameters after cycloplegia with cyclopentolate hydrochloride 1% using a dual Scheimpflug imaging system. In this prospective cross-sectional study patients aged 10 to 40 years who were referred for optometric evaluation enrolled and underwent autorefraction and corneal imaging with the Galilei dual Scheimpflug system before and 30 minutes after twice instillation of medication. Changes in refraction and astigmatism were investigated. Corneal biometrics including anterior and posterior corneal curvatures, total corneal power and corneal pachymetry were compared before and after cycloplegia. Two hundred and twelve eyes of 106 subjects with mean age of 28 ± 5 years including 201 myopic and 11 hyperopic eyes were evaluated. Mean spherical equivalent refractive error before cycloplegia was -3.4 ± 2.6 D. A mean hyperopic shift of 0.4 ± 0.5 D occurred after cycloplegia ( P biometrics should be considered before cataract and refractive surgeries.

  13. Intrastromal corneal ring implants for corneal thinning disorders: an evidence-based analysis.

    Science.gov (United States)

    2009-01-01

    progressively thins causing a cone-like bulge or forward protrusion in response to the normal pressure of the eye. Thinning occurs primarily in the stoma layers and is believed to be a breakdown in the collagen network. This bulging can lead to an irregular shape or astigmatism of the cornea and, because the anterior part of the cornea is largely responsible for the focusing of light on the retina, results in loss of visual acuity. This can make even simple daily tasks, such as driving, watching television or reading, difficult to perform. Keratoconus (KC) is the most common form of corneal thinning disorder and is a noninflammatory chronic disease process. Although the specific causes of the biomechanical alterations that occur in KC are unknown, there is a growing body of evidence to suggest that genetic factors may play an important role. KC is a rare condition (management for this condition follows a step-wise approach depending on disease severity. Contact lenses are the primary treatment of choice when there is irregular astigmatism associated with the disease. When patients can no longer tolerate contact lenses or when lenses no longer provide adequate vision, patients are referred for corneal transplant. Keratoconus is one of the leading indications for corneal transplants and has been so for the last three decades. Yet, despite high graft survival rates of up to 20 years, there are reasons to defer receiving transplants for as long as possible. Patients with keratoconus are generally young and life-long term graft survival would be an important consideration. The surgery itself involves lengthy time off work and there are potential complications from long term steroid use following surgery, as well as the risk of developing secondary cataracts, glaucoma etc. After transplant, recurrent KC is possible with need for subsequent intervention. Residual refractive errors and astigmatism can remain challenging after transplantation and high refractive surgery rates and re

  14. Glaucoma after corneal replacement.

    Science.gov (United States)

    Baltaziak, Monika; Chew, Hall F; Podbielski, Dominik W; Ahmed, Iqbal Ike K

    Glaucoma is a well-known complication after corneal transplantation surgery. Traditional corneal transplantation surgery, specifically penetrating keratoplasty, has been slowly replaced by the advent of new corneal transplantation procedures: primarily lamellar keratoplasties. There has also been an emergence of keratoprosthesis implants for eyes that are high risk of failure with penetrating keratoplasty. Consequently, there are different rates of glaucoma, pathogenesis, and potential treatment in the form of medical, laser, or surgical therapy. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Anatomical characterization of central, apical and minimal corneal thickness

    Directory of Open Access Journals (Sweden)

    Federico Saenz-Frances

    2014-08-01

    Full Text Available AIM: To anatomically locate the points of minimum corneal thickness and central corneal thickness (pupil center in relation to the corneal apex.METHODS: Observational, cross-sectional study, 299 healthy volunteers. Thickness at the corneal apex (AT, minimum corneal thickness (MT and corneal thickness at the pupil center (PT were determined using the pentacam. Distances from the corneal apex to MT (MD and PT (PD were calculated and their quadrant position (taking the corneal apex as the reference determined:point of minimum thickness (MC and point of central thickness (PC depending on the quadrant position. Two multivariate linear regression models were constructed to examine the influence of age, gender, power of the flattest and steepest corneal axes, position of the flattest axis, corneal volume (determined using the Pentacam and PT on MD and PD. The effects of these variables on MC and PC were also determined in two multinomial regression models.RESULTS: MT was located at a mean distance of 0.909 mm from the apex (79.4% in the inferior-temporal quadrant. PT was located at a mean distance of 0.156 mm from the apex. The linear regression model for MD indicated it was significantly influenced by corneal volume (B=-0.024; 95%CI:-0.043 to -0.004. No significant relations were identified in the linear regression model for PD or the multinomial logistic regressions for MC and PC.CONCLUSION: MT was typically located at the inferior-temporal quadrant of the cornea and its distance to the corneal apex tended to decrease with the increment of corneal volume.

  16. Second Harmonic Generation Imaging Analysis of Collagen Arrangement in Human Cornea.

    Science.gov (United States)

    Park, Choul Yong; Lee, Jimmy K; Chuck, Roy S

    2015-08-01

    To describe the horizontal arrangement of human corneal collagen bundles by using second harmonic generation (SHG) imaging. Human corneas were imaged with an inverted two photon excitation fluorescence microscope. The excitation laser (Ti:Sapphire) was tuned to 850 nm. Backscatter signals of SHG were collected through a 425/30-nm bandpass emission filter. Multiple, consecutive, and overlapping image stacks (z-stacks) were acquired to generate three dimensional data sets. ImageJ software was used to analyze the arrangement pattern (irregularity) of collagen bundles at each image plane. Collagen bundles in the corneal lamellae demonstrated a complex layout merging and splitting within a single lamellar plane. The patterns were significantly different in the superficial and limbal cornea when compared with deep and central regions. Collagen bundles were smaller in the superficial layer and larger in deep lamellae. By using SHG imaging, the horizontal arrangement of corneal collagen bundles was elucidated at different depths and focal regions of the human cornea.

  17. Treatment of chest burn contracture causing respiratory compromise with island release and grafting using cross-link collagen and Integra™ bilayer dressing

    Directory of Open Access Journals (Sweden)

    Neil Doctor

    2014-04-01

    Full Text Available Post-burn skin contractures of the anterior and lateral abdomen and chest may result in respiratory compromise due to limitation of rib excursion. This case report describes a young man with respiratory compromise limiting his daily activity and function, as a result of a 90% burn sustained 6 years previously. Release of his chest and upper abdomen was achieved using “island” scar releases and a cross-linked bovine tendon collagen and glycosaminoglycan and a semi-permeable polysiloxane bilayer matrix dressing (Integra™ followed by subsequent split thickness skin graft. An immediate increase in maximal inspiratory volume was obtained intra-operatively and in the im­mediate post-operative period, and this improvement was sustained after healing of all wounds with subjective relief of the patient’s symptoms.

  18. The carboxy-terminal pyridinoline cross-linked telopeptide of type I collagen in serum as a marker of bone resorption

    DEFF Research Database (Denmark)

    Hassager, C; Jensen, L T; Pødenphant, J

    1994-01-01

    Carboxy-terminal pyridinoline cross-linked telopeptide of type I collagen (ICTP) in serum has recently been proposed as a new biochemical marker of bone resorption. In the present study we compared serum ICTP with radiopharmaceutical and histomorphometric measurements of bone turnover...... in postmenopausal women with mild osteoporosis, and assessed the effect of hormone replacement therapy (HRT) (2 mg 17 beta-estradiol plus 1 mg norethisterone daily) and anabolic steroid therapy (50 mg nandrolone decanoate (ND) i.m. every 3 weeks) on serum ICTP in two double-blind placebo-controlled studies with 55...... to 75-year-old women. Serum ICTP measured by radioimmunoassay (RIA) correlated significantly with the 24-hour whole body retention of 99m-technetium diphosphonate (Rho = 0.47, P

  19. Shear bond strength of composite to deep dentin after treatment with two different collagen cross-linking agents at varying time intervals.

    Science.gov (United States)

    Srinivasulu, S; Vidhya, S; Sujatha, M; Mahalaxmi, S

    2012-01-01

    This in vitro study evaluated the shear bond strength of composite resin to deep dentin using a total etch adhesive after treatment with two collagen cross-linking agents at varying time intervals. Thirty freshly extracted human maxillary central incisors were sectioned longitudinally into equal mesial and distal halves (n=60). The proximal deep dentin was exposed, maintaining a remaining dentin thickness (RDT) of approximately 1 mm. The specimens were randomly divided into three groups based on the surface treatment of dentin prior to bonding as follows: group I (n=12, control): no prior dentin surface treatment; group II (n=24): dentin surface pretreated with 10% sodium ascorbate; and group III (n=24): dentin surface pretreated with 6.5% proanthocyanidin. Groups II and III were further subdivided into two subgroups of 12 specimens each, based on the pretreatment time of five minutes (subgroup A) and 10 minutes (subgroup B). Shear bond strength of the specimens was tested with a universal testing machine, and the data were statistically analyzed. Significantly higher shear bond strength to deep dentin was observed in teeth treated with 10% sodium ascorbate (group II) and 6.5% proanthocyanidin (group III) compared to the control group (group I). Among the collagen cross-linkers used, specimens treated with proanthocyanidin showed significantly higher shear bond strength values than those treated with sodium ascorbate. No significant difference was observed between the five-minute and 10-minute pretreatment times in groups II and III. It can be concluded that dentin surface pretreatment with both 10% sodium ascorbate and 6.5% proanthocyanidin resulted in significant improvement in bond strength of resin composite to deep dentin.

  20. The ratio 1660/1690 cm(-1) measured by infrared microspectroscopy is not specific of enzymatic collagen cross-links in bone tissue.

    Science.gov (United States)

    Farlay, Delphine; Duclos, Marie-Eve; Gineyts, Evelyne; Bertholon, Cindy; Viguet-Carrin, Stéphanie; Nallala, Jayakrupakar; Sockalingum, Ganesh D; Bertrand, Dominique; Roger, Thierry; Hartmann, Daniel J; Chapurlat, Roland; Boivin, Georges

    2011-01-01

    In postmenopausal osteoporosis, an impairment in enzymatic cross-links (ECL) occurs, leading in part to a decline in bone biomechanical properties. Biochemical methods by high performance liquid chromatography (HPLC) are currently used to measure ECL. Another method has been proposed, by Fourier Transform InfraRed Imaging (FTIRI), to measure a mature PYD/immature DHLNL cross-links ratio, using the 1660/1690 cm(-1) area ratio in the amide I band. However, in bone, the amide I band composition is complex (collagens, non-collagenous proteins, water vibrations) and the 1660/1690 cm(-1) by FTIRI has never been directly correlated with the PYD/DHLNL by HPLC. A study design using lathyritic rats, characterized by a decrease in the formation of ECL due to the inhibition of lysyl oxidase, was used in order to determine the evolution of 1660/1690 cm(-1) by FTIR Microspectroscopy in bone tissue and compare to the ECL quantified by HPLC. The actual amount of ECL was quantified by HPLC on cortical bone from control and lathyritic rats. The lathyritic group exhibited a decrease of 78% of pyridinoline content compared to the control group. The 1660/1690 cm(-1) area ratio was increased within center bone compared to inner bone, and this was also correlated with an increase in both mineral maturity and mineralization index. However, no difference in the 1660/1690 cm(-1) ratio was found between control and lathyritic rats. Those results were confirmed by principal component analysis performed on multispectral infrared images. In bovine bone, in which PYD was physically destructed by UV-photolysis, the PYD/DHLNL (measured by HPLC) was strongly decreased, whereas the 1660/1690 cm(-1) was unmodified. In conclusion, the 1660/1690 cm(-1) is not related to the PYD/DHLNL ratio, but increased with age of bone mineral, suggesting that a modification of this ratio could be mainly due to a modification of the collagen secondary structure related to the mineralization process.

  1. The Ratio 1660/1690 cm−1 Measured by Infrared Microspectroscopy Is Not Specific of Enzymatic Collagen Cross-Links in Bone Tissue

    Science.gov (United States)

    Farlay, Delphine; Duclos, Marie-Eve; Gineyts, Evelyne; Bertholon, Cindy; Viguet-Carrin, Stéphanie; Nallala, Jayakrupakar; Sockalingum, Ganesh D.; Bertrand, Dominique; Roger, Thierry; Hartmann, Daniel J.; Chapurlat, Roland; Boivin, Georges

    2011-01-01

    In postmenopausal osteoporosis, an impairment in enzymatic cross-links (ECL) occurs, leading in part to a decline in bone biomechanical properties. Biochemical methods by high performance liquid chromatography (HPLC) are currently used to measure ECL. Another method has been proposed, by Fourier Transform InfraRed Imaging (FTIRI), to measure a mature PYD/immature DHLNL cross-links ratio, using the 1660/1690 cm−1 area ratio in the amide I band. However, in bone, the amide I band composition is complex (collagens, non-collagenous proteins, water vibrations) and the 1660/1690 cm−1 by FTIRI has never been directly correlated with the PYD/DHLNL by HPLC. A study design using lathyritic rats, characterized by a decrease in the formation of ECL due to the inhibition of lysyl oxidase, was used in order to determine the evolution of 1660/1690 cm−1 by FTIR Microspectroscopy in bone tissue and compare to the ECL quantified by HPLC. The actual amount of ECL was quantified by HPLC on cortical bone from control and lathyritic rats. The lathyritic group exhibited a decrease of 78% of pyridinoline content compared to the control group. The 1660/1690 cm−1 area ratio was increased within center bone compared to inner bone, and this was also correlated with an increase in both mineral maturity and mineralization index. However, no difference in the 1660/1690 cm−1 ratio was found between control and lathyritic rats. Those results were confirmed by principal component analysis performed on multispectral infrared images. In bovine bone, in which PYD was physically destructed by UV-photolysis, the PYD/DHLNL (measured by HPLC) was strongly decreased, whereas the 1660/1690 cm−1 was unmodified. In conclusion, the 1660/1690 cm−1 is not related to the PYD/DHLNL ratio, but increased with age of bone mineral, suggesting that a modification of this ratio could be mainly due to a modification of the collagen secondary structure related to the mineralization process. PMID:22194900

  2. The effects of different cross-linking conditions on collagen-based nanocomposite scaffolds—an in vitro evaluation using mesenchymal stem cells

    International Nuclear Information System (INIS)

    Suchý, Tomáš; Šupová, Monika; Sucharda, Zbyněk; Rýglová, Šárka; Žaloudková, Margit; Sauerová, Pavla; Kalbáčová, Marie Hubálek; Verdánová, Martina; Sedláček, Radek

    2015-01-01

    Nanocomposite scaffolds which aimed to imitate a bone extracellular matrix were prepared for bone surgery applications. The scaffolds consisted of polylactide electrospun nano/sub-micron fibres, a natural collagen matrix supplemented with sodium hyaluronate and natural calcium phosphate nano-particles (bioapatite). The mechanical properties of the scaffolds were improved by means of three different cross-linking agents: N-(3-dimethylamino propyl)-N’-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in an ethanol solution (EDC/NHS/EtOH), EDC/NHS in a phosphate buffer saline solution (EDC/NHS/PBS) and genipin. The effect of the various cross-linking conditions on the pore size, structure and mechanical properties of the scaffolds were subsequently studied. In addition, the mass loss, the swelling ratio and the pH of the scaffolds were determined following their immersion in a cell culture medium. Furthermore, the metabolic activity of human mesenchymal stem cells (hMSCs) cultivated in scaffold infusions for 2 and 7 days was assessed. Finally, studies were conducted of cell adhesion, proliferation and penetration into the scaffolds. With regard to the structural stability of the tested scaffolds, it was determined that EDC/NHS/PBS and genipin formed the most effectively cross-linked materials. Moreover, it was discovered that the genipin cross-linked scaffold also provided the best conditions for hMSC cultivation. In addition, the infusions from all the scaffolds were found to be non-cytotoxic. Thus, the genipin and EDC/NHS/PBS cross-linked scaffolds can be considered to be promising biomaterials for further in vivo testing and bone surgery applications. (paper)

  3. Late Stage of Corneal Decompensation Caused by Progressive Keratoconus: Can We Treat It and Save the Cornea?

    Directory of Open Access Journals (Sweden)

    Igor Knezović

    2015-01-01

    Full Text Available Aim. To report a case of 40-year-old male with progressive bilateral keratoconus who had undergone transepithelial phototherapeutic keratectomy (TE-PTK and corneal collagen cross-linking (CXL using hypoosmolar riboflavin solution in a same day procedure. Methods. Eye examination showed that UCDVA on both eyes was 0,01 according to Snellen charts, and slit lamp biomicroscopy showed paracentral diffuse intrastromal corneal haze. Anterior OCT marked stromal hyperreflective zones and localized paracentral thinning of the cornea. Scheimpflug tomography noted keratoconus stages III-IV on both eyes. After 40/35 microns TE-PTK, a CXL was performed for 30 minutes using hypoosmolar riboflavin solution. The left eye was treated first and the right eye 1 month after. Follow-up period was 10 months. Results. One month after the treatment both eyes showed improvement in corneal topography and the UCDVA was better. Eight months after the treatment BSCVA improved to 0,6 in both eyes using Rose K2 contact lenses and remained stable. Conclusion. TE-PTK and CXL using hypotonic riboflavin solution as a same day procedure have been shown to be a safe and promising method in this case of progressive keratoconus. It was necessary to consider certain parameters that could influence the safety and the final outcome of this combined protocol.

  4. New Details of the Human Corneal Limbus Revealed With Second Harmonic Generation Imaging.

    Science.gov (United States)

    Park, Choul Yong; Lee, Jimmy K; Zhang, Cheng; Chuck, Roy S

    2015-09-01

    To report novel findings of the human corneal limbus by using second harmonic generation (SHG) imaging. Corneal limbus was imaged by using an inverted two-photon excitation fluorescence microscope. Laser (Ti:Sapphire) was tuned at 850 nm for two-photon excitation. Backscatter signals of SHG and autofluorescence (AF) were collected through a 425/30-nm emission filter and a 525/45-emission filter, respectively. Multiple, consecutive, and overlapping image stacks (z-stack) were acquired for the corneal limbal area. Two novel collagen structures were revealed by SHG imaging at the limbus: an anterior limbal cribriform layer and presumed anchoring fibers. Anterior limbal cribriform layer is an intertwined reticular collagen architecture just beneath the limbal epithelial niche and is located between the peripheral cornea and Tenon's/scleral tissue. Autofluorescence imaging revealed high vascularity in this structure. Central to the anterior limbal cribriform layer, radial strands of collagen were found to connect the peripheral cornea to the limbus. These presumed anchoring fibers have both collagen and elastin and were found more extensively in the superficial layers than deep layer and were absent in very deep limbus near Schlemm's canal. By using SHG imaging, new details of the collagen architecture of human corneal limbal area were elucidated. High resolution images with volumetric analysis revealed two novel collagen structures.

  5. Human corneal epithelial subpopulations

    DEFF Research Database (Denmark)

    Søndergaard, Chris Bath

    2013-01-01

    Corneal epithelium is being regenerated throughout life by limbal epithelial stem cells (LESCs) believed to be located in histologically defined stem cell niches in corneal limbus. Defective or dysfunctional LESCs result in limbal stem cell deficiency (LSCD) causing pain and decreased visual acuity...... subpopulations in human corneal epithelium using a combination of laser capture microdissection and RNA sequencing for global transcriptomic profiling. We compared dissociation cultures, using either expansion on γ-irradiated NIH/3T3 feeder cells in serum-rich medium or expansion directly on plastic in serum...

  6. Betanin reduces the accumulation and cross-links of collagen in high-fructose-fed rat heart through inhibiting non-enzymatic glycation.

    Science.gov (United States)

    Han, Junyan; Tan, Chang; Wang, Yiheng; Yang, Shaobin; Tan, Dehong

    2015-02-05

    We attempted to determine whether betanin (from natural pigments) that has antioxidant properties would be protective against fructose-induced diabetic cardiac fibrosis in Sprague-Dawley rats. Fructose water solution (30%) was accessed freely, and betanin (25 and 100 mg/kg/d) was administered by intra-gastric gavage continuously for 60 d. Rats were sacrificed after overnight fast. The rat blood and left ventricle were collected. In vitro antiglycation assay in bovine serum albumin/fructose system was also performed. In rats treated only with fructose, levels of plasma markers: glucose, insulin, HOMA and glycated hemoglobin rised, left ventricle collagen accumulated and cross-linked, profibrotic factor-transforming growth factor (TGF)-β1 and connective tissue growth factor (CTGF) protein expression increased, and soluble collagen decreased, compared with those in normal rats, showing fructose induces diabetic cardiac fibrosis. Treatment with betanin antagonized the changes of these parameters, demonstrating the antifibrotic role of betanin in the selected diabetic models. In further mechanistic study, betanin decreased protein glycation indicated by the decreased levels of protein glycation reactive intermediate (methylglyoxal), advanced glycation end product (N(ε)-(carboxymethyl) lysine) and receptors for advanced glycation end products (AGEs), antagonized oxidative stress and nuclear factor-κB activation elicited by fructose feeding, suggesting inhibition of glycation, oxidative stress and nuclear factor-κB activation may be involved in the antifibrotic mechanisms. Betanin also showed anitglycative effect in BSA/fructose system, which supported that anitglycation was involved in betanin's protective roles in vivo. Taken together, the potential for using betanin as an auxillary therapy for diabetic cardiomyopathy deserves to be explored further. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  7. Prevalence and causes of corneal blindness.

    Science.gov (United States)

    Wang, Haijing; Zhang, Yaoguang; Li, Zhijian; Wang, Tiebin; Liu, Ping

    2014-04-01

    The study aimed to assess the prevalence and causes of corneal blindness in a rural northern Chinese population. Cross-sectional study. The cluster random sampling method was used to select the sample. This population-based study included 11 787 participants of all ages in rural Heilongjiang Province, China. These participants underwent a detailed interview and eye examination that included the measurement of visual acuity, slit-lamp biomicroscopy and direct ophthalmoscopy. An eye was considered to have corneal blindness if the visual acuity was blindness and low vision. Among the 10 384 people enrolled in the study, the prevalence of corneal blindness is 0.3% (95% confidence interval 0.2-0.4%). The leading cause was keratitis in childhood (40.0%), followed by ocular trauma (33.3%) and keratitis in adulthood (20.0%). Age and illiteracy were found to be associated with an increased prevalence of corneal blindness. Blindness because of corneal diseases in rural areas of Northern China is a significant public health problem that needs to be given more attention. © 2013 Royal Australian and New Zealand College of Ophthalmologists.

  8. An age-related study of morphology and cross-link composition of collagen fibrils in the digital flexor tendons of young thoroughbred horses.

    Science.gov (United States)

    Patterson-Kane, J C; Parry, D A; Birch, H L; Goodship, A E; Firth, E C

    1997-01-01

    The superficial digital flexor tendon is the most commonly injured tendon in the racing Thoroughbred. Despite the clinical significance of this structure, only limited data exist regarding normal age-related morphology of the tensile units, the collagen fibrils. The age at which these collagen fibrils become mature in composition and structure may be of importance. Consequently, the association of age and collagen fibril crosslink composition, diameter distribution and crimp morphology in the superficial and deep digital flexor tendons of Thoroughbreds up to and including three years of age has been studied. Replacement of immature crosslinks, peaking of the collagen fibril mass-average diameter and collagen fibril index, and stabilization of collagen crimp morphology changes supported the hypothesis that both digital flexor tendons become mature in structure by two years of age.

  9. Trifluoperazine: corneal endothelial phototoxicity

    International Nuclear Information System (INIS)

    Hull, D.S.; Csukas, S.; Green, K.

    1983-01-01

    Trifluoperazine is used for the treatment of psychiatric disorders. Perfusion of corneal endothelial cells with trifluoperazine-HC1 concurrent with exposure to long wavelength ultraviolet light resulted in a corneal swelling rate greater than that found in perfused corneas not exposed to ultraviolet light. Exposure of endothelial cells to 25 W incandescent light during perfusion with trifluoperazine-HC1 did not result in a higher corneal swelling rate compared to those perfused in the dark. The increased corneal swelling rate could be produced by pre-exposure of the trifluoperazine-HC1 perfusing solution to ultraviolet light suggesting the production of toxic photoproducts during exposure of trifluoperazine-HC1 to ultraviolet light. Perfusion of corneal endothelial cells with non-ultraviolet illuminated trifluoperazine-HC1 had no effect on endothelial cell membranes or ultrastructure. This is in contrast to cells perfused with trifluoperazine-HC1 that had been exposed to ultraviolet light in which there was an alteration of mitochondria and a loss of cytoplasmic homogeneity. The data imply that the trifluoperazine-HC1 photoproduct had an adverse effect on cellular transport mechanisms. The study also further demonstrates the value of the corneal endothelial cell model for identifying the physiological and anatomical changes occuring in photo-induced toxic reactions. (author)

  10. Construction of Anterior Hemi-Corneal Equivalents Using Nontransfected Human Corneal Cells and Transplantation in Dog Models.

    Science.gov (United States)

    Xu, Bin; Song, Zhan; Fan, Tingjun

    2017-11-01

    Tissue-engineered human anterior hemi-cornea (TE-aHC) is a promising equivalent for treating anterior lamellar keratopathy to surmount the severe shortage of donated corneas. This study was intended to construct a functional TE-aHC with nontransfected human corneal stromal (ntHCS) and epithelial (ntHCEP) cells using acellular porcine corneal stromata (aPCS) as a carrier scaffold, and evaluate its biological functions in a dog model. To construct a TE-aHC, ntHCS cells were injected into an aPCS scaffold and cultured for 3 days; then, ntHCEP cells were inoculated onto the Bowman's membrane of the scaffold and cultured for 5 days under air-liquid interface condition. After its morphology and histological structure were characterized, the constructed TE-aHC was transplanted into dog eyes via lamellar keratoplasty. The corneal transparency, thickness, intraocular pressure, epithelial integrity, and corneal regeneration were monitored in vivo, and the histological structure and histochemical property were examined ex vivo 360 days after surgery, respectively. The results showed that the constructed TE-aHC was highly transparent and composed of a corneal epithelium of 7-8 layer ntHCEP cells and a corneal stroma of regularly aligned collagen fibers and well-preserved glycosaminoglycans with sparsely distributed ntHCS cells, mimicking a normal anterior hemi-cornea (aHC). Moreover, both ntHCEP and ntHCS cells maintained positive expression of their marker and functional proteins. After transplantation into dog eyes, the constructed TE-aHC acted naturally in terms of morphology, structure and inherent property, and functioned well in maintaining corneal clarity, thickness, normal histological structure, and composition in dog models by reconstructing a normal aHC, which could be used as a promising aHC equivalent in corneal regenerative medicine and aHC disorder therapy. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  11. A Rare Form of Corneal Opacity Associated with Spondyloepiphyseal Dysplasia Congenita

    Directory of Open Access Journals (Sweden)

    Yuichiro Ishida

    2018-02-01

    Full Text Available A 13-year-old Japanese female diagnosed with spondyloepiphyseal dysplasia congenita (SEDC was referred for ophthalmologic evaluation. Examination with slit-lamp and optical coherence tomography revealed bilateral thin cornea with diffuse corneal opacity which was localised at the posterior stromal depth in the central cornea. Unlike the two previously reported cases of diffuse and nodular patterns of corneal opacity in SEDC, the current case exhibited a rare form of corneal opacity. SEDC is one of the type II collagenopathies, characterised by dwarfism because the mutations in COL2A1 prevent bone growth. Although the existence of type II collagen has not been reported in the human corneal stroma, the aetiology of the opacity in the corneal stroma in SEDC type II collagenopathy is of interest.

  12. Alpha-ketoglutarate decreases serum levels of C-terminal cross-linking telopeptide of type I collagen (CTX) in postmenopausal women with osteopenia: six-month study.

    Science.gov (United States)

    Filip, Rafał S; Pierzynowski, Stefan G; Lindegard, Birger; Wernerman, Jan; Haratym-Maj, Agnieszka; Podgurniak, Małgorzata

    2007-03-01

    Several studies have shown that alpha-ketoglutaric acid (AKG) increases serum levels of proline and has beneficial effects on skeletal development. We studied the effect of alpha-ketoglutaric (AKG) acid calcium salt (6 g AKG and 1.68 Ca/day) or calcium alone (1.68 Ca/day) on serum C-terminal cross-linked telopeptide of type I collagen (CTX) and osteocalcin (OC), as well as on lumbar spine bone mineral density (BMD) in a randomized, parallel group, double-blind, 6-month study conducted on 76 postmenopausal women with osteopenia. The maximum decrease of the mean CTX level in the AKG-Ca group was observed after 24 weeks (37.0%, p = 0.006). The differences in CTX between study groups were statistically significant after 12 and 24 weeks. The OC serum level was not affected by treatments. The BMD of the AKG-Ca group increased by 1.6% from baseline; however, the difference between treatment groups was estimated as 0.9% (non-significant). This study suggests the potential usefulness of AKG-Ca in osteopenic postmenopausal women. AKG-Ca induced beneficial changes in serum CTX, which was consistent with preserving the bone mass in the lumbar spine; however, the long-term effect needs to be further investigated.

  13. Serum Bone Resorption Markers after Parathyroidectomy for Renal Hyperparathyroidism: Correlation Analyses for the Cross-Linked N-telopeptide of Collagen I and Tartrate-Resistant Acid Phosphatase

    Directory of Open Access Journals (Sweden)

    Kuo-Chin Hung

    2012-01-01

    Full Text Available Patients on long-term dialysis may develop secondary hyperparathyroidism (SHPT with increased serum concentrations of bone resorption markers such as the cross-linked N-telopeptide of type I collagen (NTX and type-5b tartrate-resistant acid phosphatase (TRAP. When SHPT proves refractory to treatment, parathyroidectomy (PTX may be needed. Renal patients on maintenance HD who received PTX for refractory SHPT (n=23 or who did not develop refractory SHPT (control subjects; n=25 were followed prospectively for 4 weeks. Serum intact parathyroid hormone (iPTH, NTX, TRAP, and bone alkaline phosphatase (BAP concentrations were measured serially and correlation analyses were performed. iPTH values decreased rapidly and dramatically. BAP values increased progressively with peak increases observed at 2 weeks after surgery. NTX and TRAP values decreased concurrently and progressively through 4 weeks following PTX. A significant correlation between TRAP and NTX values was observed before PTX but not at 4 weeks after PTX. Additionally, the fractional changes in serum TRAP were larger than those in serum NTX at all times examined after PTX. Serum iPTH, TRAP, and NTX values declined rapidly following PTX for SHPT. Serum TRAP values declined to greater degrees than serum NTX values throughout the 4-week period following PTX.

  14. The Influence of Lamellar Orientation on Corneal Material Behavior: Biomechanical and Structural Changes in an Avian Corneal Disorder

    Science.gov (United States)

    Elsheikh, Ahmed; Kassem, Wael; Kamma-Lorger, Christina S.; Hocking, Paul M.; White, Nick; Inglehearn, Chris F.; Ali, Manir; Meek, Keith M.

    2011-01-01

    Purpose. Retinopathy, globe enlarged (RGE) is an inherited genetic disease of chickens with a corneal phenotype characterized by loss of tissue curvature and changes in peripheral collagen fibril alignment. This study aimed to characterize the material behavior of normal and RGE chicken corneas under inflation and compare this with new spatial- and depth-resolved microstructural information to investigate how stromal fibril architecture determines corneal behavior under intraocular pressure (IOP). Methods. Six RGE chicken corneas and six age-matched normal controls were tested using trephinate inflation and their stress-strain behavior determined as a function of posterior pressure. Second harmonic generation mulitphoton microscopy was used to compare the in-plane appearance and degree of through-plane interlacing of collagen lamellae between normal and mutant corneas. Results. RGE corneas displayed a 30–130% increase in material stiffness [Etangent(RGE) = 0.94 ± 0.18 MPa to 3.09 ± 0.66 MPa; Etangent(normals) = 0.72 ± 0.13 MPa to 1.34 ± 0.35 MPa] (P ≤ 0.05). The normal in-plane disposition of anterior collagen in the peripheral cornea was altered in RGE but through-plane lamellar interlacing was unaffected. Conclusions. This article demonstrates changes in corneal material behavior in RGE that are qualitatively consistent with microstructural collagen alterations identified both herein and previously. This study indicates that, in general, changes in stromal fibril orientation may significantly affect corneal material behavior and thereby its response to IOP. PMID:21051696

  15. Evaluating the Toxicity/Fixation Balance for Corneal Cross-Linking With Sodium Hydroxymethylglycinate (SMG) and Riboflavin-UVA (CXL) in an Ex Vivo Rabbit Model Using Confocal Laser Scanning Fluorescence Microscopy.

    Science.gov (United States)

    Kim, Su-Young; Babar, Natasha; Munteanu, Emilia Laura; Takaoka, Anna; Zyablitskaya, Mariya; Nagasaki, Takayuki; Trokel, Stephen L; Paik, David C

    2016-04-01

    To develop methods to delineate the relationship between endothelial cell toxicity and tissue fixation (toxicity/fixation) using sodium hydroxymethylglycinate (SMG), a formaldehyde releaser, and riboflavin-UVA photochemical corneal cross-linking (CXL) for therapeutic tissue cross-linking of the cornea. Eleven fresh cadaveric rabbit heads were used for ex vivo corneal cross-linking simulation. After epithelial debridement, the tissue was exposed to 1/4 max (9.8 mM) or 1/3 max (13 mM) SMG at pH 8.5 for 30 minutes or riboflavin-UVA (CXL). The contralateral cornea served as a paired control. Postexposure, cross-linking efficacy was determined by thermal denaturation temperature (Tm) and endothelial damage was assessed using calcein AM and ethidium homodimer staining (The Live/Dead Kit). Confocal laser scanning fluorescence microscopy was used to generate live/dead cell counts using a standardized algorithm. The ΔTm after CXL, 1/3 SMG, and 1/4 SMG was 2.2 ± 0.9°C, 1.3 ± 0.5°C, and 1.1 ± 0.5°C, respectively. Endothelial cell damage was expressed as the percent of dead cells/live + dead cells counted per high-power field. The values were 3 ± 1.7% (control) and 8.9 ± 11.1% (CXL) (P = 0.390); 1 ± 0.2% (control) and 19.5 ± 32.2% (1/3 max SMG) (P = 0.426); and 2.7 ± 2.4% (control) and 2.8 ± 2.2% (1/4 max SMG) (P = 0.938). The values for endothelial toxicity were then indexed over the shift in Tm to yield a toxicity/fixation index. The values were as follows: 2.7 for CXL, 14 for 1/3 max, and 0.1 for 1/4 max. Quarter max (1/4 max = 9.8 mM) SMG effectively cross-linked tissue and was nontoxic to endothelial cells. Thus, SMG is potentially a compound that could achieve both desired effects.

  16. HPLC detection of loss rate and cell migration of HUVECs in a proanthocyanidin cross-linked recombinant human collagen-peptide (RHC)–chitosan scaffold

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jing; Deng, Aipeng [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yang, Yang [Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Gao, Lihu; Xu, Na; Liu, Xin; Hu, Lunxiang; Chen, Junhua [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yang, Shulin, E-mail: yshulin@njust.edu.cn [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2015-11-01

    Porous scaffolds with appropriate pore structure, biocompatibility, mechanical property and processability play an important role in tissue engineering. In this paper, we fabricated a recombinant human collagen-peptide (RHC)–chitosan scaffold cross-linked by premixing 30% proanthocyanidin (PA) in one-step freeze-drying. To remove the residual acetic acid, optimized 0.2 M phosphate buffer of pH 6.24 with 30% ethanol (PBSE) was selected to neutralize the lyophilized scaffold followed by three times deionized water rinse. Ninhydrin assay was used to characterize the components loss during the fabrication process. To detect the exact RHC loss under optimized neutralization condition, high performance liquid chromatography (HPLC) equipped size exclusion chromatography column was used and the total RHC loss rate through PBSE rinse was 19.5 ± 5.08%. Fourier transform infrared spectroscopy (FT-IR) indicated hydrogen bonding among RHC, chitosan and PA, it also presented a probative but not strong hydrophobic interaction between phenyl rings of polyphenols and pyrrolidine rings of proline in RHC. Further, human umbilical vein endothelial cell (HUVEC) viability analyzed by a scanning electron microscope (SEM) and acridine orange/ethidium bromide (AO/EB) fluorescence staining exhibited that this scaffold could not only promote cell proliferation on scaffold surface but also permit cells migration into the scaffold. qRT-PCR exhibited that the optimized scaffold could stimulate angiogenesis associated genes VEGF and CD31 expression. These characterizations indicated that this scaffold can be considered as an ideal candidate for tissue engineering. - Highlights: • PA cross-linked recombinant human collagen–chitosan scaffold. • Fabrication in one-step lyophilization with neutralization. • HPLC detection of RHC loss rate • HUVEC proliferation and migration in scaffold • Angiogenesis associated gene expressions were increased in scaffold cell culturing.

  17. New composite materials prepared by calcium phosphate precipitation in chitosan/collagen/hyaluronic acid sponge cross-linked by EDC/NHS.

    Science.gov (United States)

    Kaczmarek, B; Sionkowska, A; Kozlowska, J; Osyczka, A M

    2018-02-01

    Nowadays, fabrication of composite materials based on biopolymers is a rising field due to potential for bone repair and tissue engineering application. Blending of different biopolymers and incorporation of inorganic particles in the blend can lead to new materials with improved physicochemical properties and biocompatibility. In this work 3D porous structures called scaffolds based on chitosan, collagen and hyaluronic acid were obtained through the lyophilization process. Scaffolds were cross-linked by EDC/NHS. Infrared spectra for the materials were made, the percentage of swelling, scaffolds porosity and density, mechanical parameters, thermal stability were studied. Moreover, the scaffolds were used as matrixes for the calcium phosphate in situ precipitation. SEM images were taken and EDX analysis was carried out for calcium and phosphorous content determination in the scaffold. In addition, the adhesion and proliferation of human osteosarcoma SaOS-2 cells was examined on obtained scaffolds. The results showed that the properties of 3D composites cross-linked by EDC/NHS were altered after the addition of 1, 2 and 5% hyaluronic acid. Mechanical parameters, thermal stability and porosity of scaffolds were improved. Moreover, calcium and phosphorous were found in each kind of scaffold. SEM images showed that the precipitation was homogeneously carried in the whole volume of samples. Attachment of SaOS-2 cells to all modified materials was better compared to unmodified control and proliferation of these cells was markedly increased on scaffolds with precipitated calcium phosphate. Obtained materials can provide the support useful in tissue engineering and regenerative medicine. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Distrofia corneal de Schnyder

    Directory of Open Access Journals (Sweden)

    Michel Guerra Almaguer

    Full Text Available La principal entidad hereditaria con depósitos de lípidos en el estroma corneal es la distrofia cristalina central, conocida como distrofia de Schnyder, quien la describió en Suiza en 1927. Se caracteriza por depósitos blanco-amarillentos en el estroma corneal central y superficial. Se presenta un paciente de 28 años, del sexo masculino y piel negra, con antecedente de salud anterior. Acudió a consulta y refirió una disminución de la visión y cambio de coloración progresiva de ambos ojos, de años de evolución. En la exploración oftalmológica de ambos ojos se apreciaron lesiones blanquecinas anulares a nivel del estroma corneal, con ligera turbidez corneal central. Los estudios refractivos realizados constataron un astigmatismo hipermetrópico simple. El resto del examen oftalmológico fue negativo. Para el diagnóstico de certeza se empleó el microscopio confocal. Se concluye que el caso presenta una distrofia corneal estromal de tipo cristalina, de Schnyder.

  19. Response of human corneal fibroblasts on silk film surface patterns.

    Science.gov (United States)

    Gil, Eun Seok; Park, Sang-Hyug; Marchant, Jeff; Omenetto, Fiorenzo; Kaplan, David L

    2010-06-11

    Transparent, biodegradable, mechanically robust, and surface-patterned silk films were evaluated for the effect of surface morphology on human corneal fibroblast (hCF) cell proliferation, orientation, and ECM deposition and alignment. A series of dimensionally different surface groove patterns were prepared from optically graded glass substrates followed by casting poly(dimethylsiloxane) (PDMS) replica molds. The features on the patterned silk films showed an array of asymmetric triangles and displayed 37-342 nm depths and 445-3 582 nm widths. hCF DNA content on all patterned films were not significantly different from that on flat silk films after 4 d in culture. However, the depth and width of the grooves influenced cell alignment, while the depth differences affected cell orientation; overall, deeper and narrower grooves induced more hCF orientation. Over 14 d in culture, cell layers and actin filament organization demonstrated that confluent hCFs and their cytoskeletal filaments were oriented along the direction of the silk film patterned groove axis. Collagen type V and proteoglycans (decorin and biglycan), important markers of corneal stromal tissue, were highly expressed with alignment. Understanding corneal stromal fibroblast responses to surface features on a protein-based biomaterial applicable in vivo for corneal repair potential suggests options to improve corneal tissue mimics. Further, the approaches provide fundamental biomaterial designs useful for bioengineering oriented tissue layers, an endemic feature in most biological tissue structures that lead to critical tissue functions.

  20. Granular corneal dystrophy

    OpenAIRE

    Castillo Pérez, Alexeide de la C; Vilches Lescaille, Daysi; Noriega, Justo Luis; Martínez Balido, Daneel; León Balbón, Bárbaro Ramón; León Bernal, Danysleidi

    2015-01-01

    Las distrofias corneales constituyen un conjunto de enfermedades que presentan, en su mayoría, una baja incidencia y se caracterizan por acúmulo de material hialino o amiloide que disminuyen la transparencia corneal. La distrofia granular es una enfermedad autosómica dominante que presenta opacidades grises en el estroma superficial central de la córnea y se hacen visibles en la primera y segunda décadas de la vida, lo que provoca disminución de la visión más significativa cerca de los 40 año...

  1. Airbag induced corneal ectasia.

    Science.gov (United States)

    Mearza, Ali A; Koufaki, Fedra N; Aslanides, Ioannis M

    2008-02-01

    To report a case of airbag induced corneal ectasia. Case report. A patient 3 years post-LASIK developed bilateral corneal ectasia worse in the right eye following airbag deployment in a road traffic accident. At last follow up, best corrected vision was 20/40 with -4.00/-4.00 x 25 in the right eye and 20/25 with -1.25/-0.50 x 135 in the left eye. This is a rare presentation of trauma induced ectasia in a patient post-LASIK. It is possible that reduction in biomechanical integrity of the cornea from prior refractive surgery contributed to this presentation.

  2. Characterization of Genipin-Modified Dentin Collagen

    Directory of Open Access Journals (Sweden)

    Hiroko Nagaoka

    2014-01-01

    Full Text Available Application of biomodification techniques to dentin can improve its biochemical and biomechanical properties. Several collagen cross-linking agents have been reported to strengthen the mechanical properties of dentin. However, the characteristics of collagen that has undergone agent-induced biomodification are not well understood. The objective of this study was to analyze the effects of a natural cross-linking agent, genipin (GE, on dentin discoloration, collagen stability, and changes in amino acid composition and lysyl oxidase mediated natural collagen cross-links. Dentin collagen obtained from extracted bovine teeth was treated with three different concentrations of GE (0.01%, 0.1%, and 0.5% for several treatment times (0–24 h. Changes in biochemical properties of NaB3H4-reduced collagen were characterized by amino acid and cross-link analyses. The treatment of dentin collagen with GE resulted in a concentration- and time-dependent pigmentation and stability against bacterial collagenase. The lysyl oxidase-mediated trivalent mature cross-link, pyridinoline, showed no difference among all groups while the major divalent immature cross-link, dehydro-dihydroxylysinonorleucine/its ketoamine in collagen treated with 0.5% GE for 24 h, significantly decreased compared to control (P< 0.05. The newly formed GE-induced cross-links most likely involve lysine and hydroxylysine residues of collagen in a concentration-dependent manner. Some of these cross-links appear to be reducible and stabilized with NaB3H4.

  3. Efficient Generation of Human Embryonic Stem Cell-Derived Corneal Endothelial Cells by Directed Differentiation.

    Directory of Open Access Journals (Sweden)

    Kathryn L McCabe

    Full Text Available To generate human embryonic stem cell derived corneal endothelial cells (hESC-CECs for transplantation in patients with corneal endothelial dystrophies.Feeder-free hESC-CECs were generated by a directed differentiation protocol. hESC-CECs were characterized by morphology, expression of corneal endothelial markers, and microarray analysis of gene expression.hESC-CECs were nearly identical morphologically to primary human corneal endothelial cells, expressed Zona Occludens 1 (ZO-1 and Na+/K+ATPaseα1 (ATPA1 on the apical surface in monolayer culture, and produced the key proteins of Descemet's membrane, Collagen VIIIα1 and VIIIα2 (COL8A1 and 8A2. Quantitative PCR analysis revealed expression of all corneal endothelial pump transcripts. hESC-CECs were 96% similar to primary human adult CECs by microarray analysis.hESC-CECs are morphologically similar, express corneal endothelial cell markers and express a nearly identical complement of genes compared to human adult corneal endothelial cells. hESC-CECs may be a suitable alternative to donor-derived corneal endothelium.

  4. Corneal changes with accommodation using dual Scheimpflug photography.

    Science.gov (United States)

    Sisó-Fuertes, Irene; Domínguez-Vicent, Alberto; del Águila-Carrasco, Antonio; Ferrer-Blasco, Teresa; Montés-Micó, Robert

    2015-05-01

    To assess whether corneal parameters and aberrations are affected by accommodation. Optics Department, University of Valencia, Valencia, Spain. Prospective cross-sectional study. The Galilei G4 dual Scheimpflug device was used to obtain data on the anterior and posterior axial curvatures, total corneal power (TCP), and corneal pachymetry from 3 corneal zones (central: 0.0 up to 4.0 mm; paracentral or mid: 4.0 up to 7.0 mm; peripheral: 7.0 up to 10.0 mm) in young emmetropic eyes in the unaccommodated and 4 accommodated states (from -1.0 to -4.0 diopters [D] in 1.0 D steps). The 2nd-, 3rd-, and 4th-order aberrations as well as the root mean square (RMS) were also determined for the entire cornea at the same accommodative demands. The study evaluated 7 subjects (12 eyes). No significant changes in any measured parameter were found during accommodation for any corneal zone (P > .05). Statistically significant differences were found in the various corneal zones when it was assumed they were constant with accommodation (P the high standard deviation values. Different parameters in various zones of the cornea as well as corneal aberrations were stable during accommodation. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

  5. Altered corneal biomechanical properties in children with osteogenesis imperfecta.

    Science.gov (United States)

    Lagrou, Lisa M; Gilbert, Jesse; Hannibal, Mark; Caird, Michelle S; Thomas, Inas; Moroi, Sayoko E; Bohnsack, Brenda L

    2018-04-07

    To evaluate biomechanical corneal properties in children with osteogenesis imperfecta (OI). A prospective, observational, case-control study was conducted on children 6-19 years of age diagnosed with OI. Patients with OI and healthy control subjects underwent complete ophthalmic examinations. Additional tests included Ocular Response Analyzer (ORA) and ultrasonic pachymetry. Primary outcomes were central corneal thickness (CCT), corneal hysteresis (CH), and corneal resistance factor (CRF). Intraocular pressure (IOP) was measured directly by either iCare or Goldmann applanation and indirectly by the ORA (Goldmann-correlated and corneal-compensated IOP). Statistically significant differences between OI and control groups were determined using independent samples t test. A total of 10 of 18 OI cases (mean age, 13 ± 4.37 years; 8 males) and 30 controls (mean age, 12.76 ± 2.62 years; 16 males) were able to complete the corneal biomechanics and pachymetry testing. Children with OI had decreased CH (8.5 ± 1.0 mm Hg vs 11.6 ± 1.2 mm Hg [P < 0.001]), CRF (9.0 ± 1.9 mm Hg vs 11.5 ± 1.5 [P < 0.001]) and CCT (449.8 ± 30.8 μm vs 568 ± 47.6 μm [P < 0.001]) compared to controls. The corneal-compensated IOP was significantly higher in OI cases (18.8 ± 3.1 mm Hg) than in controls (15.0 ± 1.6 mm Hg, P < 0.004), but there was no significant difference in Goldmann-correlated IOP (16.3 ± 4.2 mm Hg vs 15.8 ± 2.2 mm Hg). Collagen defects in OI alter corneal structure and biomechanics. Children with OI have decreased CH, CRF, and CCT, resulting in IOPs that are likely higher than measured by tonometry. These corneal alterations are present at a young age in OI. Affected individuals should be routinely screened for glaucoma and corneal pathologies. Copyright © 2018 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

  6. Quantitative Assessment of Ultrastructure and Light Scatter in Mouse Corneal Debridement Wounds

    Science.gov (United States)

    Boote, Craig; Du, Yiqin; Morgan, Sian; Harris, Jonathan; Kamma-Lorger, Christina S.; Hayes, Sally; Lathrop, Kira L.; Roh, Danny S.; Burrow, Michael K.; Hiller, Jennifer; Terrill, Nicholas J.; Funderburgh, James L.; Meek, Keith M.

    2012-01-01

    Purpose. The mouse has become an important wound healing model with which to study corneal fibrosis, a frequent complication of refractive surgery. The aim of the current study was to quantify changes in stromal ultrastructure and light scatter that characterize fibrosis in mouse corneal debridement wounds. Methods. Epithelial debridement wounds, with and without removal of basement membrane, were produced in C57BL/6 mice. Corneal opacity was measured using optical coherence tomography, and collagen diameter and matrix order were quantified by x-ray scattering. Electron microscopy was used to visualize proteoglycans. Quantitative PCR (Q-PCR) measured mRNA transcript levels for several quiescent and fibrotic markers. Results. Epithelial debridement without basement membrane disruption produced a significant increase in matrix disorder at 8 weeks, but minimal corneal opacity. In contrast, basement membrane penetration led to increases in light scatter, matrix disorder, and collagen diameter, accompanied by the appearance of abnormally large proteoglycans in the subepithelial stroma. This group also demonstrated upregulation of several quiescent and fibrotic markers 2 to 4 weeks after wounding. Conclusions. Fibrotic corneal wound healing in mice involves extensive changes to collagen and proteoglycan ultrastructure, consistent with deposition of opaque scar tissue. Epithelial basement membrane penetration is a deciding factor determining the degree of ultrastructural changes and resulting opacity. PMID:22467580

  7. Validation of Na,K-ATPase pump function of corneal endothelial cells for corneal regenerative medicine.

    Science.gov (United States)

    Hatou, Shin; Higa, Kazunari; Inagaki, Emi; Yoshida, Satoru; Kimura, Erika; Hayashi, Ryuhei; Tsujikawa, Motokazu; Tsubota, Kazuo; Nishida, Kohji; Shimmura, Shigeto

    2013-12-01

    Tissue-engineering approaches to cultivate corneal endothelial cells (CECs) or induce CECs from stem cells are under investigation for the treatment of endothelial dysfunction. Before clinical application, a validation method to determine the quality of these cells is required. In this study, we quantified the endothelial pump function required for maintaining the corneal thickness using rabbit CECs (RCECs) and a human CEC line (B4G12). The potential difference of RCECs cultured on a permeable polyester membrane (Snapwell), B4G12 cells on Snapwell, or B4G12 cells on a collagen membrane (CM6) was measured by an Ussing chamber system, and the effect of different concentrations of ouabain (Na,K-ATPase specific inhibitor) was obtained. A mathematical equation derived from the concentration curve revealed that 2 mM ouabain decreases pump function of RCECs to 1.0 mV, and 0.6 mM ouabain decreases pump function of B4G12 on CM6 to 1.0 mV. Ouabain injection into the anterior chamber of rabbit eyes at a concentration of pump function >1.0 mV is required to maintain the corneal thickness. These results can be used for standardization of CEC pump function and validation of tissue-engineered CEC sheets for clinical use.

  8. Spontaneous Corneal Hydrops in a Patient with a Corneal Ulcer

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    Hatim Batawi

    2016-01-01

    Full Text Available Purpose: We report the case of a 77-year-old man with no history of keratoconus or other ectatic disorders who presented with corneal hydrops in the setting of a corneal ulcer. The risk factors, pathogenesis and treatment options of corneal hydrops are discussed. Method: This is an observational case report study. Results: A 77-year-old man presented with a 1-day history of severe pain, redness, mucous discharge and photophobia in the right eye. A slit-lamp examination of the right eye showed an area of focal corneal edema and protrusion. Within the area of edema and protrusion, there was an infiltrate with an overlying epithelial defect consistent with an infectious corneal ulcer. The Seidel test showed no leakage, so a clinical diagnosis of corneal hydrops associated with nonperforated corneal ulcer was made. With appropriate antibiotic treatment, the corneal ulcer and hydrops both resolved over a 1-month period. Conclusion: Corneal hydrops can occur in the setting of corneal infections.

  9. Collagen derived serum markers in carcinoma of the prostate

    DEFF Research Database (Denmark)

    Rudnicki, M; Jensen, L T; Iversen, P

    1995-01-01

    Three new collagen markers deriving from the collagenous matrix, e.g. carboxyterminal propeptide of type I procollagen (PICP), carboxy-terminal pyridinoline cross-linked telopeptide of type I collagen (ICTP), and aminoterminal propeptide of type III procollagen (PIIINP) were used for the diagnose...

  10. A STUDY ON PREVALENCE AND CAUSES OF CORNEAL BLINDNESS IN PAEDIATRIC AGE GROUP

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    E. Ramadevi

    2017-12-01

    Full Text Available BACKGROUND Corneal disease is responsible for less than 2% of blindness in children in industrialised countries. In poor countries of the world, corneal scarring occurs due to vitamin A deficiency, measles and ophthalmia neonatorum. Thus, corneal disease is an important cause of blindness among children living in developing nations, which already carry a major burden of blindness. The aim of the study is to study the1. Prevalence of corneal blindness in the paediatric age group. 2. Causes of corneal blindness in the paediatric age group. 3. Morbidity of corneal blindness in the paediatric age group. MATERIALS AND METHODS It was cross-sectional observational study. Study Period- December 2014 to August 2016. Study Done- Government General Hospital, Kakinada. Sample Size- 50 patients. Inclusion Criteria- Children of age group 6 to 12 years with corneal blindness who have attended the outpatient department during the study period. Exclusion Criteria- Children with childhood blindness other than corneal pathology. Study Tools- Predesigned, semi-structured questionnaire regarding age, sex and age of onset of visual loss, laterality, history of ocular injury, vitamin A immunisation, family history of consanguinity and place of residence and socioeconomic status was taken. Visual acuity was measured using an E optotype and Landolt broken C chart with best corrected vision. Visual loss was classified according to the WHO categories of visual impairment. Ophthalmic examination was done by slit lamp and B scan. RESULTS Ocular trauma and corneal ulcers are most common cause of corneal blindness. 84% of corneal blindness cases were preventable and curable. CONCLUSION Trauma was the commonest cause of corneal blindness followed by infectious keratitis. 84% of corneal blindness was preventable and curable. Most causes of corneal blindness were avoidable.

  11. Impact of Facial Conformation on Canine Health: Corneal Ulceration

    Science.gov (United States)

    Packer, Rowena M. A.; Hendricks, Anke; Burn, Charlotte C.

    2015-01-01

    Concern has arisen in recent years that selection for extreme facial morphology in the domestic dog may be leading to an increased frequency of eye disorders. Corneal ulcers are a common and painful eye problem in domestic dogs that can lead to scarring and/or perforation of the cornea, potentially causing blindness. Exaggerated juvenile-like craniofacial conformations and wide eyes have been suspected as risk factors for corneal ulceration. This study aimed to quantify the relationship between corneal ulceration risk and conformational factors including relative eyelid aperture width, brachycephalic (short-muzzled) skull shape, the presence of a nasal fold (wrinkle), and exposed eye-white. A 14 month cross-sectional study of dogs entering a large UK based small animal referral hospital for both corneal ulcers and unrelated disorders was carried out. Dogs were classed as affected if they were diagnosed with a corneal ulcer using fluorescein dye while at the hospital (whether referred for this disorder or not), or if a previous diagnosis of corneal ulcer(s) was documented in the dogs’ histories. Of 700 dogs recruited, measured and clinically examined, 31 were affected by corneal ulcers. Most cases were male (71%), small breed dogs (mean± SE weight: 11.4±1.1 kg), with the most commonly diagnosed breed being the Pug. Dogs with nasal folds were nearly five times more likely to be affected by corneal ulcers than those without, and brachycephalic dogs (craniofacial ratio dogs. A 10% increase in relative eyelid aperture width more than tripled the ulcer risk. Exposed eye-white was associated with a nearly three times increased risk. The results demonstrate that artificially selecting for these facial characteristics greatly heightens the risk of corneal ulcers, and such selection should thus be discouraged to improve canine welfare. PMID:25969983

  12. The Collagen-Binding Adhesin Is a Virulence Factor in Staphylococcus aureus Keratitis

    Science.gov (United States)

    Rhem, Marcus N.; Lech, Elizabeth M.; Patti, Joseph M.; McDevitt, Damien; Höök, Magnus; Jones, Dan B.; Wilhelmus, Kirk R.

    2000-01-01

    A collagen-binding strain of Staphylococcus aureus produced suppurative inflammation in a rabbit model of soft contact lens-associated bacterial keratitis more often than its collagen-binding-negative isogenic mutant. Reintroduction of the cna gene on a multicopy plasmid into the mutant helped it regain its corneal adherence and infectivity. The topical application of a collagen-binding peptide before bacterial challenge decreased S. aureus adherence to deepithelialized corneas. These data suggest that the collagen-binding adhesin is involved in the pathogenesis of S. aureus infection of the cornea. PMID:10816547

  13. A Comparative Study of Vertebrate Corneal Structure: The Evolution of a Refractive Lens.

    Science.gov (United States)

    Winkler, Moritz; Shoa, Golroxan; Tran, Stephanie T; Xie, Yilu; Thomasy, Sarah; Raghunathan, Vijay K; Murphy, Christopher; Brown, Donald J; Jester, James V

    2015-04-01

    Although corneal curvature plays an important role in determining the refractive power of the vertebrate eye, the mechanisms controlling corneal shape remain largely unknown. To address this question, we performed a comparative study of vertebrate corneal structure to identify potential evolutionarily based changes that correlate with the development of a corneal refractive lens. Nonlinear optical (NLO) imaging of second-harmonic-generated (SHG) signals was used to image collagen and three-dimensionally reconstruct the lamellar organization in corneas from different vertebrate clades. Second-harmonic-generated images taken normal to the corneal surface showed that corneal collagen in all nonmammalian vertebrates was organized into sheets (fish and amphibians) or ribbons (reptiles and birds) extending from limbus to limbus that were oriented nearly orthogonal (ranging from 77.7°-88.2°) to their neighbors. The slight angular offset (2°-13°) created a rotational pattern that continued throughout the full thickness in fish and amphibians and to the very posterior layers in reptiles and birds. Interactions between lamellae were limited to "sutural" fibers in cartilaginous fish, and occasional lamellar branching in fish and amphibians. There was a marked increase in lamellar branching in higher vertebrates, such that birds ≫ reptiles > amphibians > fish. By contrast, mammalian corneas showed a nearly random collagen fiber organization with no orthogonal, chiral pattern. Our data indicate that nonmammalian vertebrate corneas share a common orthogonal collagen structural organization that shows increased lamellar branching in higher vertebrate species. Importantly, mammalian corneas showed a different structural organization, suggesting a divergent evolutionary background.

  14. Collagen organization in the chicken cornea and structural alterations in the retinopathy, globe enlarged (rge) phenotype--an X-ray diffraction study.

    Science.gov (United States)

    Boote, Craig; Hayes, Sally; Jones, Simon; Quantock, Andrew J; Hocking, Paul M; Inglehearn, Chris F; Ali, Manir; Meek, Keith M

    2008-01-01

    An investigation into the collagenous structure of the mature avian cornea is presented. Wide-angle X-ray diffraction is employed to assess collagen organization in 9-month-old chicken corneas. The central 2-4mm corneal region features a preponderance of fibrils directed along the superior-inferior and nasal-temporal orthogonal meridians. More peripherally the orientation of fibrils alters in favor of a predominantly tangential arrangement. The chicken cornea appears to be circumscribed by an annulus of fibrils that extends into the limbus. The natural arrangement of collagen in the chicken cornea is discussed in relation to corneal shape and the mechanical requirements of avian corneal accommodation. Equivalent data are also presented from age-matched blind chickens affected with the retinopathy, globe enlarged (rge) mutation, characterized by an abnormally thick and flat cornea. The data indicate considerable realignment and redistribution of collagen lamellae in the peripheral rge cornea. In contrast to normal chickens, no obvious tangential collagen alignment was evident in the periphery of rge corneas. In mammals, the presence of a limbal fibril annulus is believed to be important in corneal shape preservation. We postulate that corneal flattening in rge chickens may be related to biomechanical changes brought about by an alteration in collagen arrangement at the corneal periphery.

  15. Fracture mechanics of collagen fibrils

    DEFF Research Database (Denmark)

    Svensson, Rene B; Mulder, Hindrik; Kovanen, Vuokko

    2013-01-01

    Tendons are important load-bearing structures, which are frequently injured in both sports and work. Type I collagen fibrils are the primary components of tendons and carry most of the mechanical loads experienced by the tissue, however, knowledge of how load is transmitted between and within...... fibrils is limited. The presence of covalent enzymatic cross-links between collagen molecules is an important factor that has been shown to influence mechanical behavior of the tendons. To improve our understanding of how molecular bonds translate into tendon mechanics, we used an atomic force microscopy...... technique to measure the mechanical behavior of individual collagen fibrils loaded to failure. Fibrils from human patellar tendons, rat-tail tendons (RTTs), NaBH₄ reduced RTTs, and tail tendons of Zucker diabetic fat rats were tested. We found a characteristic three-phase stress-strain behavior in the human...

  16. The potential role of bioengineering and three-dimensional printing in curing global corneal blindness.

    Science.gov (United States)

    Ludwig, Parker E; Huff, Trevor J; Zuniga, Jorge M

    2018-01-01

    An insufficiency of accessible allograft tissue for corneal transplantation leaves many impaired by untreated corneal disease. There is promise in the field of regenerative medicine for the development of autologous corneal tissue grafts or collagen-based scaffolds. Another approach is to create a suitable corneal implant that meets the refractive needs of the cornea and is integrated into the surrounding tissue but does not attempt to perfectly mimic the native cornea on a cellular level. Materials that have been investigated for use in the latter concept include natural polymers such as gelatin, semisynthetic polymers like gelatin methacrylate, and synthetic polymers. There are advantages and disadvantages inherent in natural and synthetic polymers: natural polymers are generally more biodegradable and biocompatible, while synthetic polymers typically provide greater control over the characteristics or property adjustment of the materials. Additive manufacturing could aid in the precision production of keratoprostheses and the personalization of implants.

  17. Neurotrophic corneal and conjunctival xerosis

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    Svetlana Gennadyevna Zhurova

    2014-03-01

    Full Text Available Purpose: to develop a method of surgical treatment of patients with corneal ulcers of xerotic etiology and evaluate its efficacy in different time periods after operation. Materials and methods: 68 patients (86 eyes with severe dry eye syndrome complicated by xerotic corneal ulcers were examined. In all patients, the ulcer defect was covered with conjunctiva and amniotic membrane. The operation was combined with an outer tarsorrhaphy and temporary blepharorraphy. Results: All 86 eyes (100% achieved total closure of the ulcer defect, sealing of any perforation and maintaining of corneal transparency beyond the ulcer defect. Conclusion: Surgical closure of corneal ulcers with conjunctiva is an effective method of treatment of xerotic corneal ulcers. It could be recommended in patients with corneal perforation and tendency of descemetocele formation.

  18. Corneal Neurotoxicity Due to Topical Benzalkonium Chloride

    OpenAIRE

    Sarkar, Joy; Chaudhary, Shweta; Namavari, Abed; Ozturk, Okan; Chang, Jin-Hong; Yco, Lisette; Sonawane, Snehal; Khanolkar, Vishakha; Hallak, Joelle; Jain, Sandeep

    2012-01-01

    Topical application of benzalkonium chloride (BAK) to the eye causes dose-related corneal neurotoxicity. Corneal inflammation and reduction in aqueous tear production accompany neurotoxicity. Cessation of BAK treatment leads to recovery of corneal nerve density.

  19. Distrofia corneal granular

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    Alexeide de la C Castillo Pérez

    Full Text Available Las distrofias corneales constituyen un conjunto de enfermedades que presentan, en su mayoría, una baja incidencia y se caracterizan por acúmulo de material hialino o amiloide que disminuyen la transparencia corneal. La distrofia granular es una enfermedad autosómica dominante que presenta opacidades grises en el estroma superficial central de la córnea y se hacen visibles en la primera y segunda décadas de la vida, lo que provoca disminución de la visión más significativa cerca de los 40 años de edad. Presentamos dos casos clínicos de distrofia granular en pacientes hermanos de diferentes sexos, quienes acudieron a la consulta y refirieron visión nublada. El estudio de la historia familiar nos ayuda en el correcto diagnóstico y la biomicroscopia constituye el elemento más importante.

  20. Contact Lens Related Corneal Ulcer

    OpenAIRE

    Loh, KY; Agarwal, P

    2010-01-01

    A corneal ulcer caused by infection is one of the major causes of blindness worldwide. One of the recent health concerns is the increasing incidence of corneal ulcers associated with contact lens user especially if the users fail to follow specific instruction in using their contact lenses. Risk factors associated with increased risk of contact lens related corneal ulcers are: overnight wear, long duration of continuous wear, lower socio-economic classes, smoking, dry eye and poor hygiene. Th...

  1. Cell therapy of congenital corneal diseases with umbilical mesenchymal stem cells: lumican null mice.

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    Hongshan Liu

    Full Text Available BACKGROUND: Keratoplasty is the most effective treatment for corneal blindness, but suboptimal medical conditions and lack of qualified medical personnel and donated cornea often prevent the performance of corneal transplantation in developing countries. Our study aims to develop alternative treatment regimens for congenital corneal diseases of genetic mutation. METHODOLOGY/PRINCIPAL FINDINGS: Human mesenchymal stem cells isolated from neonatal umbilical cords were transplanted to treat thin and cloudy corneas of lumican null mice. Transplantation of umbilical mesenchymal stem cells significantly improved corneal transparency and increased stromal thickness of lumican null mice, but human umbilical hematopoietic stem cells failed to do the same. Further studies revealed that collagen lamellae were re-organized in corneal stroma of lumican null mice after mesenchymal stem cell transplantation. Transplanted umbilical mesenchymal stem cells survived in the mouse corneal stroma for more than 3 months with little or no graft rejection. In addition, these cells assumed a keratocyte phenotype, e.g., dendritic morphology, quiescence, expression of keratocyte unique keratan sulfated keratocan and lumican, and CD34. Moreover, umbilical mesenchymal stem cell transplantation improved host keratocyte functions, which was verified by enhanced expression of keratocan and aldehyde dehydrogenase class 3A1 in lumican null mice. CONCLUSIONS/SIGNIFICANCE: Umbilical mesenchymal stem cell transplantation is a promising treatment for congenital corneal diseases involving keratocyte dysfunction. Unlike donated corneas, umbilical mesenchymal stem cells are easily isolated, expanded, stored, and can be quickly recovered from liquid nitrogen when a patient is in urgent need.

  2. Effects of edible bird's nest (EBN on cultured rabbit corneal keratocytes

    Directory of Open Access Journals (Sweden)

    Hun Lee

    2011-10-01

    Full Text Available Abstract Background There has been no effective treatment or agent that is available for corneal injury in promoting corneal wound healing. Previous studies on edible bird's nest extract (EBN had reported the presence of hormone-like substance; avian epidermal growth factor that could stimulate cell division and enhance regeneration. This study aimed to investigate the effects of EBN on corneal keratocytes proliferative capacity and phenotypical changes. Methods Corneal keratocytes from six New Zealand White Rabbits were isolated and cultured until Passage 1. The proliferative effects of EBN on corneal keratocytes were determined by MTT assay in serum-containing medium (FDS and serum-free medium (FD. Keratocytes phenotypical changes were morphologically assessed and gene expression of aldehyde dehydrogenase (ALDH, collagen type 1 and lumican were determined through RT-PCR. Results The highest cell proliferation was observed when both media were supplemented with 0.05% and 0.1% EBN. Cell proliferation was also consistently higher in FDS compared to FD. Both phase contrast micrographs and gene expression analysis confirmed the corneal keratocytes retained their phenotypes with the addition of EBN. Conclusions These results suggested that low concentration of EBN could synergistically induce cell proliferation, especially in serum-containing medium. This could be a novel breakthrough as both cell proliferation and functional maintenance are important during corneal wound healing. The in vitro test is considered as a crucial first step for nutri-pharmaceutical formation of EBN-based eye drops before in vivo application.

  3. Collagen cross-linking by adipose-derived mesenchymal stromal cells and scar-derived mesenchymal cells: Are mesenchymal stromal cells involved in scar formation?

    NARCIS (Netherlands)

    Bogaerdt, van den A.J.; Veen, van der A.G.; Zuijlen, van P.P.; Reijnen, L.; Verkerk, M.; Bank, R.A.; Middelkoop, E.; Ulrich, M.

    2009-01-01

    In this work, different fibroblast-like (mesenchymal) cell populations that might be involved in wound healing were characterized and their involvement in scar formation was studied by determining collagen synthesis and processing. Depending on the physical and mechanical properties of the tissues,

  4. Collagen cross-linking by adipose-derived mesenchymal stromal cells and scar-derived mesenchymal cells : Are mesenchymal stromal cells involved in scar formation?

    NARCIS (Netherlands)

    van den Bogaerdt, Antoon J.; van der Veen, Vincent C.; van Zuijlen, Paul P. M.; Reijnen, Linda; Verkerk, Michelle; Bank, Ruud A.; Middelkoop, Esther; Ulrich, Magda M. W.

    2009-01-01

    In this work, different fibroblast-like (mesenchymal) cell populations that might be involved in wound healing were characterized and their involvement in scar formation was studied by determining collagen synthesis and processing. Depending on the physical and mechanical properties of the tissues,

  5. Removal of the basement membrane enhances corneal wound healing.

    Science.gov (United States)

    Pal-Ghosh, Sonali; Pajoohesh-Ganji, Ahdeah; Tadvalkar, Gauri; Stepp, Mary Ann

    2011-12-01

    Recurrent corneal erosions are painful and put patients' vision at risk. Treatment typically begins with debridement of the area around the erosion site followed by more aggressive treatments. An in vivo mouse model has been developed that reproducibly induces recurrent epithelial erosions in wild-type mice spontaneously within two weeks after a single 1.5 mm corneal debridement wound created using a dulled-blade. This study was conducted to determine whether 1) inhibiting MMP9 function during healing after dulled-blade wounding impacts erosion development and 2) wounds made with a rotating-burr heal without erosions. Oral or topical inhibition of MMPs after dulled-blade wounding does not improve healing. Wounds made by rotating-burr heal with significantly fewer erosions than dulled-blade wounds. The localization of MMP9, β4 integrin and basement membrane proteins (LN332 and type VII collagen), immune cell influx, and reinnervation of the corneal nerves were compared after both wound types. Rotating-burr wounds remove the anterior basement membrane centrally but not at the periphery near the wound margin, induce more apoptosis of corneal stromal cells, and damage more stromal nerve fibers. Despite the fact that rotating-burr wounds do more damage to the cornea, fewer immune cells are recruited and significantly more wounds resolve completely. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Intrastromal corneal ring segments for management of keratoconus

    Directory of Open Access Journals (Sweden)

    Sri Ganesh

    2013-01-01

    Full Text Available Keratoconus is a progressive corneal ectasia, which can be managed both by conservative measures like glasses or contact lenses in non-progressive cases or surgical procedures like collagen crosslinking (CXL with or without adjuvant measures like intrastromal corneal rings segments (ICRS or topography guided ablation. Various kinds of ICRS are available to the surgeon, but it is most essential to be able to plan the implantation of the ring to optimize outcomes. Aims: The aim of this study is to evaluate the visual outcome and progression in patients of keratoconus implanted with ICRS. Materials and Methods: Two different types of ICRS-Intacs (Addition Technology and Kerarings (Mediphacos Inc. were implanted in 2 different cohorts of patients and were followed-up to evaluate the outcome of the procedure. All patients underwent a complete ocular examination including best spectacle corrected visual acuity, slit lamp examination fundus examination, corneal topography and pachymetry. The ICRS implantation is done with CXL to stop the progression of the disease. Improvement in uncorrected visual acuity (UCVA, best spectacle corrected visual acuity and topographic changes were analyzed. Results: A significant improvement in keratometry and vision was seen in both groups. Conclusion: ICRS have been found to reduce corneal irregularity and flatten keratometry with improvement in UCVA and best corrected visual acuity.

  7. Corneal complications and visual impairment in vernal keratoconjunctivitis patients

    International Nuclear Information System (INIS)

    Arif, A.S.; Aaqil, B.; Siddiqui, A.; Nazneen, Z.; Farooq, U.

    2017-01-01

    Vernal kerato-conjunctivitis (VKC) is an infrequent but serious form of allergic conjunctivitis common in warm and humid areas where air is rich in allergens. It affects both eyes asymmetrically. Although VKC is a self-limiting disease but visions affecting corneal complications influence the quality of life in school children. The aim of this study was to list the corneal complications due to this condition and to find out the extent of visual impairment among VKC patients. Methods: This cross-sectional study was conducted in the department of Ophthalmology, Benazir Bhutto Shaheed Hospital on 290 eyes of diagnosed cases of VKC. The diagnosis of VKC was made on the basis of history and examination. Visual acuity was recorded using Snellen's notation and visual impairment was classified according to World Health Organization classification for visual disabilities. Results: The mean age of presentation was 10.83+-6.13 years. There were 207 (71.4%) males and 83 (28.6%) females. Corneal scarring was observed in 59 (20.3%) eyes. Keratoconus was found to be in 17 (5.9%) eyes. Shield ulcer was detected in 09 (3.1%) eyes while 07 (2.4%) eyes had corneal neovascularization. Majority of the patients with visual loss had corneal scarring and the complication that led to severe visual loss in most of the eyes was Keratoconus. Conclusion: Vernal kerato-conjunctivitis in the presence of corneal complications is a sight threatening disease and can lead to severe visual impairment. (author)

  8. Glutaraldehyde cross-linking of amniotic membranes affects their nanofibrous structures and limbal epithelial cell culture characteristics.

    Science.gov (United States)

    Lai, Jui-Yang; Ma, David Hui-Kang

    2013-01-01

    Given that the cells can sense nanometer dimensions, the chemical cross-linking-mediated alteration in fibrillar structure of collagenous tissue scaffolds is critical to determining their cell culture performances. This article explores, for the first time, the effect of nanofibrous structure of glutaraldehyde (GTA) cross-linked amniotic membrane (AM) on limbal epithelial cell (LEC) cultivation. Results of ninhydrin assays demonstrated that the amount of new cross-links formed between the collagen chains is significantly increased with increasing the cross-linking time from 1 to 24 hours. By transmission electron microscopy, the AM treated with GTA for a longer duration exhibited a greater extent of molecular aggregation, thereby leading to a considerable increase in nanofiber diameter and resistance against collagenase degradation. In vitro biocompatibility studies showed that the samples cross-linked with GTA for 24 hours are not well-tolerated by the human corneal epithelial cell cultures. When the treatment duration is less than 6 hours, the biological tissues cross-linked with GTA for a longer time may cause slight reductions in 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt, and anti-inflammatory activities. Nevertheless, significant collagen molecular aggregation also enhances the stemness gene expression, indicating a high ability of these AM matrices to preserve the progenitors of LECs in vitro. It is concluded that GTA cross-linking of collagenous tissue materials may affect their nanofibrous structures and corneal epithelial stem cell culture characteristics. The AM treated with GTA for 6 hours holds promise for use as a niche for the expansion and transplantation of limbal epithelial progenitor cells.

  9. Dynamic corneal deformation response and integrated corneal tomography

    Directory of Open Access Journals (Sweden)

    Marcella Q Salomão

    2018-01-01

    Full Text Available Measuring corneal biomechanical properties is still challenging. There are several clinical applications for biomechanical measurements, including the detection of mild or early forms of ectatic corneal diseases. This article reviews clinical applications for biomechanical measurements provided by the Corvis ST dynamic non contact tonometer

  10. Structure of collagen-glycosaminoglycan matrix and the influence to its integrity and stability.

    Science.gov (United States)

    Bi, Yuying; Patra, Prabir; Faezipour, Miad

    2014-01-01

    Glycosaminoglycan (GAG) is a chain-like disaccharide that is linked to polypeptide core to connect two collagen fibrils/fibers and provide the intermolecular force in Collagen-GAG matrix (C-G matrix). Thus, the distribution of GAG in C-G matrix contributes to the integrity and mechanical properties of the matrix and related tissue. This paper analyzes the transverse isotropic distribution of GAG in C-G matrix. The angle of GAGs related to collagen fibrils is used as parameters to qualify the GAGs isotropic characteristic in both 3D and 2D rendering. Statistical results included that over one third of GAGs were perpendicular directed to collagen fibril with symmetrical distribution for both 3D matrix and 2D plane cross through collagen fibrils. The three factors tested in this paper: collagen radius, collagen distribution, and GAGs density, were not statistically significant for the strength of Collagen-GAG matrix in 3D rendering. However in 2D rendering, a significant factor found was the radius of collagen in matrix for the GAGs directed to orthogonal plane of Collagen-GAG matrix. Between two cross-section selected from Collagen-GAG matrix model, the plane cross through collagen fibrils was symmetrically distributed but the total percentage of perpendicular directed GAG was deducted by decreasing collagen radius. There were some symmetry features of GAGs angle distribution in selected 2D plane that passed through space between collagen fibrils, but most models showed multiple peaks in GAGs angle distribution. With less GAGs directed to perpendicular of collagen fibril, strength in collagen cross-section weakened. Collagen distribution was also a factor that influences GAGs angle distribution in 2D rendering. True hexagonal collagen packaging is reported in this paper to have less strength at collagen cross-section compared to quasi-hexagonal collagen arrangement. In this work focus is on GAGs matrix within the collagen and its relevance to anisotropy.

  11. Proximal collagenous gastroenteritides:

    DEFF Research Database (Denmark)

    Nielsen, Ole Haagen; Riis, Lene Buhl; Danese, Silvio

    2014-01-01

    AIM: While collagenous colitis represents the most common form of the collagenous gastroenteritides, the collagenous entities affecting the proximal part of the gastrointestinal tract are much less recognized and possibly overlooked. The aim was to summarize the latest information through a syste...

  12. The degree of collagen crosslinks in medical collagen membranes determined by water absorption

    International Nuclear Information System (INIS)

    Braczko, M.; Tederko, A.; Grzybowski, J.

    1994-01-01

    Collagen membranes were crosslinked by using three agents: glutaraldehyde, hexametylenediisocyanate, and UV irradiation. The increasing concentrations of above chemical agents or longer time of UV exposition resulted in the higher cross-links degree and in the decrease of collagen membranes swelling (measured as water absorption), their elasticity and mechanical resistance. According to American standards, the degree of collagen biomaterial cross-links is determined by measuring of the digestion time by pepsin. However, that method is very time-consuming. In our study, we have that a simple, linear regression between logarithm of digestion time by pepsin exists and it was identical for all three cross-linking agents used. We have concluded that determination of water absorption can be an alternative, simple and fast method for examination of collagen membrane cross-links degree. (author). 16 refs, 7 figs, 1 tab

  13. Fibrous mini-collagens in hydra nematocysts.

    Science.gov (United States)

    Holstein, T W; Benoit, M; Herder, G V; David, C N; Wanner, G; Gaub, H E

    1994-07-15

    Nematocysts (cnidocysts) are exocytotic organelles found in all cnidarians. Here, atomic force microscopy and field emission scanning electron microscopy reveal the structure of the nematocyst capsule wall. The outer wall consists of globular proteins of unknown function. The inner wall consists of bundles of collagen-like fibrils having a spacing of 50 to 100 nanometers and cross-striations at intervals of 32 nanometers. The fibrils consist of polymers of "mini-collagens," which are abundant in the nematocysts of Hydra. The distinct pattern of mini-collagen fibers in the inner wall can provide the tensile strength necessary to withstand the high osmotic pressure (15 megapascals) in the capsules.

  14. The Role of Titanium Surface Microtopography on Adhesion, Proliferation, Transformation, and Matrix Deposition of Corneal Cells.

    Science.gov (United States)

    Zhou, Chengxin; Lei, Fengyang; Chodosh, James; Paschalis, Eleftherios I

    2016-04-01

    Titanium (Ti) is an excellent implantable biomaterial that can be further enhanced by surface topography optimization. Despite numerous data from orthopedics and dentistry, the effect of Ti surface topography on ocular cells is still poorly understood. In light of the recent adaptation of Ti in the Boston Keratoprosthesis artificial cornea, we attempted to perform an extended evaluation of the effect of Ti surface topography on corneal cell adhesion, proliferation, cytotoxicity, transformation, and matrix deposition. Different surface topographies were generated on medical grade Ti-6Al-4V-ELI (extra-low interstitial), with linearly increased roughness (polished to grit blasted). Biological response was evaluated in vitro using human corneal limbal epithelial (HCLE) cells, stromal fibroblasts (HCF), and endothelial cells (HCEnC). None of the Ti surface topographies caused cytotoxicity to any of the three corneal cell types. However, rough Ti surface inhibited HCLE and HCF cell adhesion and proliferation, while HCEnC proliferation was unaffected. Long-term experiments with HCF revealed that rough Ti surface with R(a) (the arithmetic average of the profile height from the mean line) ≥ 1.15 μm suppressed HCF focal adhesion kinase phosphorylation, changed fibroblast morphology, and caused less aligned and reduced deposition of collagen matrix as compared to smooth Ti (R(a) ≤ 0.08 μm). In the presence of transforming growth factor β1 (TGFβ1) stimulation, rough Ti inhibited alpha-smooth muscle actin (α-SMA) expression and collagen deposition, leading to decreased myofibroblast transformation and disorganization of the collagen fibrils as compared to smooth Ti. This study suggests that Ti surface topography regulates corneal cell behavior in a tissue-dependent manner that varies across the corneal strata. Contrary to the accepted paradigm, smooth surface topography can enhance cell adhesion and proliferation and increase matrix deposition by corneal cells.

  15. Altered corneal stromal matrix organization is associated with mucopolysaccharidosis I, III and VI.

    Science.gov (United States)

    Alroy, J; Haskins, M; Birk, D E

    1999-05-01

    The presence of cloudy corneas is a prominent feature of mucopolysaccharidosis (MPS) types I and VI, but not MPS IIIA or IIIB. The cause of corneal cloudiness in MPS I and VI is speculative. Transparency of the cornea is dependent on the uniform diameter and the regular spacing and arrangement of the collagen fibrils within the stroma. Alterations in the spacing of collagen fibrils in a variety of conditions including corneal edema, scars, and macular corneal dystrophy is clinically manifested as corneal opacity. The purpose of this study was to compare the structural organization of the stromal extracellular matrix of normal corneas with that of MPS corneas. The size and arrangement of collagen fibrils in cloudy corneas from patients with MPS I were examined. The alterations observed were an increased mean fibril diameter with a broader distribution in the MPS corneas. The MPS I corneas also had altered fibril spacing and more irregular packing compared with normal control corneas. The clear corneas of patients with MPS IIIA and IIIB also showed increases in mean fibril diameter and fibril spacing. However, there was less variation indicating more regularity than seen in MPS I. In addition, corneas from cat models of certain MPS were compared to the human corneas. Cats with MPS I and VI, as well as normal control cats, were examined. Structural alterations comparable to those seen in human MPS corneas were seen in MPS I and VI cats relative to normal clear corneas. The findings suggest that cloudy corneas in MPS I and VI are in part a consequence of structural alterations in the corneal stroma, including abnormal spacing, size, and arrangement of collagen fibrils. Copyright 1999 Academic Press.

  16. Aloe vera: an in vitro study of effects on corneal wound closure and collagenase activity.

    Science.gov (United States)

    Curto, Elizabeth M; Labelle, Amber; Chandler, Heather L

    2014-11-01

    To evaluate the in vitro effects of an aloe vera solution on (i) the viability and wound healing response of corneal cells and (ii) the ability to alter collagenase and gelatinase activities. Primary cultures of corneal epithelial cells and fibroblasts were prepared from grossly normal enucleated canine globes and treated with an aloe solution (doses ranging from 0.0-2 mg/mL). Cellular viability was evaluated using a colorimetric assay. A corneal wound healing model was used to quantify cellular ingrowth across a defect made on the confluent surface. Anticollagenase and antigelatinase activities were evaluated by incubating a bacterial collagenase/gelatinase with aloe solution (doses ranging from 0.0-500 μg/mL) and comparing outcome measures to a general metalloproteinase inhibitor, 1, 10-phenanthroline, and canine serum (doses ranging from 0.0-100%). None of the concentrations of aloe solution tested significantly affected the viability of corneal epithelial cells or fibroblasts. Concentrations ≤175 μg/mL slightly accelerated corneal epithelial cell wound closure; this change was not significant. Concentrations ≥175 μg/mL significantly (P ≤ 0.001) slowed the rate of corneal fibroblast wound closure, while aloe concentrations Aloe solution did not alter the ability for collagenase to degrade gelatin or collagen Type I but increased the ability for collagenase to degrade Type IV collagen. Although additional experiments are required, lower concentrations of aloe solution may be beneficial in healing of superficial corneal wounds to help decrease fibrosis and speed epithelialization. An increase in collagenase activity with aloe vera warrants further testing before considering in vivo studies. © 2014 American College of Veterinary Ophthalmologists.

  17. Unilateral congenital corneal keloid with anterior segment mesenchymal dysgenesis and subluxated lens: case report and review of literature.

    Science.gov (United States)

    Vanathi, M; Sen, Seema; Panda, Anita; Dada, Tanuj; Behera, Geeta; Khokhar, Sudharshan

    2007-01-01

    To report the unusual association of unilateral congenital corneal keloid with anterior-segment mesenchymal dysgenesis and bilateral subluxated lens. A 20-year old man presented with a mass lesion involving the left cornea. The corneal lesion had been present since birth. On biomicroscopic examination, a well-defined vascularized, grayish-white mass occupying the whole of the left cornea was seen. The right eye showed multiple peripheral corneal opacities with iridocorneal adhesions, a poorly defined supranasal limbus, and a subluxated lens. Excision biopsy of the mass was done for histopathologic examination. Histopathologic examination of the excised corneal mass showed features consistent with that of a corneal keloid: thickened keratinized epithelium, absent Bowman membrane layer, and fibrovascular hyperplasia composed of hyalinized collagen fibers with irregular orientation of the collagen lamellae. During penetrating keratoplasty of the left eye, an anomalous iris pattern with poorly defined angle and a supranasal subluxated lens was also observed. Extraction of the subluxated lens was also done. The graft failed subsequent to a nonhealing persistent epithelial defect. Our case report highlights the rare association of a unilateral congenital corneal keloid with anterior-segment mesenchymal dysgenesis and bilateral subluxated lens.

  18. The Antifibrosis Effects of Peroxisome Proliferator-Activated Receptor δ on Rat Corneal Wound Healing after Excimer Laser Keratectomy

    Directory of Open Access Journals (Sweden)

    Yun Gu

    2014-01-01

    Full Text Available Corneal stromal fibrosis characterized by myofibroblasts and abnormal extracellular matrix (ECM is usually the result of inappropriate wound healing. The present study tested the hypothesis that the ligand activation of peroxisome proliferator-activated receptor (PPAR δ had antifibrosis effects in a rat model of corneal damage. Adult Sprague-Dawley rats underwent bilateral phototherapeutic keratectomy (PTK. The eyes were randomized into four groups: PBS, GW501516 (a selective agonist of PPARδ, GSK3787 (a selective antagonist of PPARδ, or GW501516 combined with GSK3787. The agents were subconjunctivally administered twice a week until sacrifice. The cellular aspects of corneal wound healing were evaluated with in vivo confocal imaging and postmortem histology. A myofibroblast marker (α-smooth muscle actin and ECM production (fibronectin, collagen type III and collagen type I were examined by immunohistochemistry and RT-PCR. At the early stages of wound healing, GW501516 inhibited reepithelialization and promoted angiogenesis. During the remodeling phase of wound healing, GW501516 attenuated the activation and proliferation of keratocytes, which could be reversed by GSK3787. GW501516 decreased transdifferentiation from keratocytes into myofibroblasts, ECM synthesis, and corneal haze. These results demonstrate that GW501516 controls corneal fibrosis and suggest that PPARδ may potentially serve as a therapeutic target for treating corneal scars.

  19. GAKG-RGEKG an Epitope That Provokes Immune Cross-Reactivity between Prevotella sp. and Human Collagen: Evidence of Molecular Mimicry in Chronic Periodontitis

    Directory of Open Access Journals (Sweden)

    Gustavo Alberto Obando-Pereda

    2016-01-01

    Full Text Available Periodontal disease afflicts 20% of world population. This process usually occurs in the form of being lethargic and chronic, and consequently this disease is known as chronic process. All chronic diseases constantly cause activation of the immune system, and therefore the presentation of microbial peptides which are presented to lymphocytes by professional antigen presenting cells can present microbial peptides very similar to important structures of human economy causing autoimmune diseases, process known as molecular mimicry. Thus, the aim of this study was to verify the presence of molecular mimicry phenomenon between periodontopathogens and human proteins. Blasting microbes of Socransky periodontal complexes against human collagen were performed and then the proteins with similarities were modelled and were screened in the MHI binding virtual methods. The epitopes selected were produced and plasma of chronic periodontal volunteers was obtained and a dot immunobinding assay was performed. Hypothetical protein of Prevotella sp. and human collagen epitopes with high similarities were positive for dot immunobinding assay. With this result it can be suggested that the mimicry phenomena can occur on periodontal disease.

  20. Endocytic collagen degradation

    DEFF Research Database (Denmark)

    Madsen, Daniel H.; Jürgensen, Henrik J.; Ingvarsen, Signe Ziir

    2012-01-01

    it crucially important to understand both the collagen synthesis and turnover mechanisms in this condition. Here we show that the endocytic collagen receptor, uPARAP/Endo180, is a major determinant in governing the balance between collagen deposition and degradation. Cirrhotic human livers displayed a marked...... up-regulation of uPARAP/Endo180 in activated fibroblasts and hepatic stellate cells located close to the collagen deposits. In a hepatic stellate cell line, uPARAP/Endo180 was shown to be active in, and required for, the uptake and intracellular degradation of collagen. To evaluate the functional...... groups of mice clearly revealed a fibrosis protective role of uPARAP/Endo180. This effect appeared to directly reflect the activity of the collagen receptor, since no compensatory events were noted when comparing the mRNA expression profiles of the two groups of mice in an array system focused on matrix-degrading...

  1. Corneal Toxicity Following Exposure to Asclepias Tuberosa.

    Science.gov (United States)

    Mikkelsen, Lauge Hjorth; Hamoudi, Hassan; Gül, Cigdem Altuntas; Heegaard, Steffen

    2017-01-01

    To present a case of corneal toxicity following exposure to milky plant latex from Asclepias tuberosa. A 70-year-old female presented with blurred vision and pain in her left eye after handling an Ascepias tuberosa . Clinical examination revealed a corneal stromal oedema with small epithelial defects. The corneal endothelium was intact and folds in Descemets membrane were observed. The oedema was treated with chloramphenicol, dexamethasone and scopolamine. The corneal oedema had appeared after corneal exposure to the plant, Asclepias tuberosa , whose latex contains cardenolides that inhibit the Na + / K + -ATPase in the corneal endothelium. The oedema resolved after 96 hours. After nine months the best corrected visual acuity was 20/20. Corneal toxicity has previously been reported for plants of the Asclepias family. This is a rare case describing severe corneal toxicity caused by exposure to latex from Asclepias tuberosa . Handling of plants of the Asclepias family should be kept as a differential diagnosis in cases of acute corneal toxicity.

  2. CONTACT LENS RELATED CORNEAL ULCER

    Directory of Open Access Journals (Sweden)

    AGARWAL P

    2010-01-01

    Full Text Available A corneal ulcer caused by infection is one of the major causes of blindness worldwide. One of the recent health concerns is the increasing incidence of corneal ulcers associated with contact lens user especially if the users fail to follow specific instruction in using their contact lenses. Risk factors associated with increased risk of contact lens related corneal ulcers are:overnight wear, long duration of continuous wear, lower socio-economic classes, smoking, dry eye and poor hygiene. The presenting symptoms of contact lens related corneal ulcers include eye discomfort, foreign body sensation and lacrimation. More serious symptoms are redness (especially circum-corneal injection, severe pain, photophobia, eye discharge and blurring of vision. The diagnosis is established by a thorough slit lamp microscopic examination with fluorescein staining and corneal scraping for Gram stain and culture of the infective organism. Delay in diagnosing and treatment can cause permanent blindness, therefore an early referral to ophthalmologist and commencing of antimicrobial therapy can prevent visual loss.

  3. Collagen derived serum markers in carcinoma of the prostate

    DEFF Research Database (Denmark)

    Rudnicki, M; Jensen, L T; Iversen, P

    1995-01-01

    Three new collagen markers deriving from the collagenous matrix, e.g. carboxyterminal propeptide of type I procollagen (PICP), carboxy-terminal pyridinoline cross-linked telopeptide of type I collagen (ICTP), and aminoterminal propeptide of type III procollagen (PIIINP) were used for the diagnose......, ICTP, and PICP did not differ between these two groups. In patients with metastatic prostatic cancer all five markers were increased compared to the level measured in patients with localized cancer (p

  4. Bilateral congenital corneal keloids and anterior segment mesenchymal dysgenesis in a case of Rubinstein-Taybi syndrome.

    Science.gov (United States)

    Rao, Srinivas K; Fan, Dorothy S P; Pang, C P; Li, Winnie W Y; Ng, Joan S K; Good, William V; Lam, Dennis S C

    2002-01-01

    To report the unusual association of bilateral corneal keloids and anterior segment mesenchymal dysgenesis in a child with Rubinstein-Taybi syndrome. Case report of a 2-year-old boy. Excision of the epicorneal mass in the right eye was followed by recurrence of the lesion. Multiple penetrating keratoplasties were unsuccessful in reconstructing the anterior segment because of recurrent corneal epithelial breakdown, suggesting limbal stem cell insufficiency. Histopathology and electron microscopy of the excised mass lesion showed features typical of a corneal keloid: thickened keratinized epithelium, absent Bowman's layer, and fibrovascular hyperplasia, with haphazard orientation of the collagen lamellae. Ultrasound biomicroscopy and intraoperative findings suggested a diagnosis of Peter anomaly, but genetic analysis did not show a PAX6 mutation. The findings in our patient add to the spectrum of ocular changes described in Rubinstein-Taybi syndrome and confirm earlier reports of poor ocular prognosis in corneal keloids and Rubinstein-Taybi syndrome.

  5. Low temperature corneal laser welding investigated by atomic force microscopy

    Science.gov (United States)

    Matteini, Paolo; Sbrana, Francesca; Tiribilli, Bruno; Pini, Roberto

    2009-02-01

    The structural modifications in the stromal matrix induced by low-temperature corneal laser welding were investigated by atomic force microscopy (AFM). This procedure consists of staining the wound with Indocyanine Green (ICG), followed by irradiation with a near-infrared laser operated at low-power densities. This induces a local heating in the 55-65 °C range. In welded tissue, extracellular components undergo heat-induced structural modifications, resulting in a joining effect between the cut edges. However, the exact mechanism generating the welding, to date, is not completely understood. Full-thickness cuts, 3.5 mm in length, were made in fresh porcine cornea samples, and these were then subjected to laser welding operated at 16.7 W/cm2 power density. AFM imaging was performed on resin-embedded semi-thin slices once they had been cleared by chemical etching, in order to expose the stromal bulk of the tissue within the section. We then carried out a morphological analysis of characteristic fibrillar features in the laser-treated and control samples. AFM images of control stromal regions highlighted well-organized collagen fibrils (36.2 +/- 8.7 nm in size) running parallel to each other as in a typical lamellar domain. The fibrils exhibited a beaded pattern with a 22-39 nm axial periodicity. Laser-treated corneal regions were characterized by a significant disorganization of the intralamellar architecture. At the weld site, groups of interwoven fibrils joined the cut edges, showing structural properties that were fully comparable with those of control regions. This suggested that fibrillar collagen is not denatured by low-temperature laser welding, confirming previous transmission electron microscopy (TEM) observations, and thus it is probably not involved in the closure mechanism of corneal cuts. The loss of fibrillar organization may be related to some structural modifications in some interfibrillar substance as proteoglycans or collagen VI. Furthermore, AFM

  6. Can Riboflavin Penetrate Stroma Without Disrupting Integrity of Corneal Epithelium in Rabbits? Iontophoresis and Ultraperformance Liquid Chromatography With Electrospray Ionization Tandem Mass Spectrometry.

    Science.gov (United States)

    Novruzlu, Şahin; Türkcü, Ümmühani Özel; Kvrak, İbrahim; Kvrak, Şeyda; Yüksel, Erdem; Deniz, Nuriye Gökçen; Bilgihan, Ayşe; Bilgihan, Kamil

    2015-08-01

    To examine riboflavin concentrations in corneas and aqueous humor from rabbits with standard and transepithelial methods and iontophoresis without disrupting the integrity of the corneal epithelium before corneal collagen cross-linking. Twenty-four eyes of 12 adult New Zealand rabbits were used. They were assigned to 4 groups, each including 6 eyes. Group 1 was exposed to the standard method and given riboflavin 0.1% after epithelial debridement. Group 2 was exposed to the transepithelial method and given benzalkonium chloride (BAC), ethylenediaminetetraacetic acid (EDTA), trometamol (TRIS), hydroxypropylmethylcellulose (HPMC), and riboflavin 0.2% 3 times at 1.5-minute intervals followed by riboflavin 0.2%. Group 3 was given riboflavin 0.1% by using 1-mA electric current for 10 minutes with the help of iontophoresis without using substances disrupting the integrity of the corneal epithelium. Group 4 received the same treatment as did group 3, except that it was given riboflavin 0.2%. Following these treatments, riboflavin concentrations in aqueous humor and corneas were measured with ultraperformance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). Riboflavin concentrations in the cornea and aqueous humor were higher in group 1 (42.4 ± 5.4 μg/g) than in the other groups. They were significantly higher in group 4 (34.2 ± 6.6 μg/g) than in group 2 (24.4 ± 1.2 μg/g) (P = 0.009) and group 3 (23.6 ± 6.1 μg/g) (P = 0.026). There was not a significant difference in corneal riboflavin concentrations between group 2 and group 3 (P = 0.937). Intrastromal and aqueous riboflavin concentrations after administration of riboflavin 0.2% through iontophoresis without disrupting the integrity of the corneal epithelium were lower than those after the standard method, but higher than those after the transepithelial method. In this study, in which riboflavin concentrations were measured with a very sensitive method

  7. Corneal Toxicity Following Exposure to Asclepias Tuberosa

    DEFF Research Database (Denmark)

    Mikkelsen, Lauge Hjorth; Hamoudi, Hassan; Gül, Cigdem Altuntas

    2017-01-01

    PURPOSE: To present a case of corneal toxicity following exposure to milky plant latex from Asclepias tuberosa. METHODS: A 70-year-old female presented with blurred vision and pain in her left eye after handling an Ascepias tuberosa. Clinical examination revealed a corneal stromal oedema with small...... epithelial defects. The corneal endothelium was intact and folds in Descemets membrane were observed. The oedema was treated with chloramphenicol, dexamethasone and scopolamine. RESULTS: The corneal oedema had appeared after corneal exposure to the plant, Asclepias tuberosa, whose latex contains cardenolides...... that inhibit the Na+/ K+-ATPase in the corneal endothelium. The oedema resolved after 96 hours. After nine months the best corrected visual acuity was 20/20. CONCLUSION: Corneal toxicity has previously been reported for plants of the Asclepias family. This is a rare case describing severe corneal toxicity...

  8. Correlation between Corneal Thickness and Degree of Myopic Refractory Error

    Directory of Open Access Journals (Sweden)

    A Mortazavi

    2005-01-01

    Full Text Available Background: corneal thickness is an important factor in refractive surgeries such as Radial Keratotomy (RK, Photo Refractive Keratotomy (PRK and Laser Insitu Keratomileusis (LASIK. This study evaluated the correlation between this factor and the degree of myopic refractory error. Methods: In this cross-sectional study, 224 myopic eyes (112 patients which had undergone LASIK operation were assessed. These patients had referred to Aban Eye Clinic, Isfahan, Iran, during August and September 2002. Corneal thickness was measured by ORB SCAN Topoghraphy, and cycloplegic refraction was performed with autorefratometery and retinoscopy. Suspected keratoconus cases and hyperopic patients were excluded. Results: The patients' age was 27.2 ± 1.36 in men (N = 35 and 30.13 ± 1.04 in women (N = 77. Mean value of myopic refractory error in male patients was 5.1 ± 0.24D and in female patients was 3.8 ± 0.36D. Mean of corneal thickness was 540 ± 5.25 µM and 530 ± 5.88 µM in male and female patients respectively. There was no correlation between the degree of myopia and corneal thickness in any of the patients. Also in this research, no relations between the age and myopia were found. Right eye (P > 0.5, r = 0.124 Left eye (P > 0.5, r = 0.104. Conclusion: Based on our findings, corneal thickness and myopic refectory error do not seem to have any relations. (r = 0.039, p = 0.684. Keywords: Corneal Thickness, Cornea, Myopia, LASIK, Refractory Error

  9. Human stem cell based corneal tissue mimicking structures using laser-assisted 3D bioprinting and functional bioinks.

    Science.gov (United States)

    Sorkio, Anni; Koch, Lothar; Koivusalo, Laura; Deiwick, Andrea; Miettinen, Susanna; Chichkov, Boris; Skottman, Heli

    2018-07-01

    There is a high demand for developing methods to produce more native-like 3D corneal structures. In the present study, we produced 3D cornea-mimicking tissues using human stem cells and laser-assisted bioprinting (LaBP). Human embryonic stem cell derived limbal epithelial stem cells (hESC-LESC) were used as a cell source for printing epithelium-mimicking structures, whereas human adipose tissue derived stem cells (hASCs) were used for constructing layered stroma-mimicking structures. The development and optimization of functional bioinks was a crucial step towards successful bioprinting of 3D corneal structures. Recombinant human laminin and human sourced collagen I served as the bases for the functional bioinks. We used two previously established LaBP setups based on laser induced forward transfer, with different laser wavelengths and appropriate absorption layers. We bioprinted three types of corneal structures: stratified corneal epithelium using hESC-LESCs, lamellar corneal stroma using alternating acellular layers of bioink and layers with hASCs, and finally structures with both a stromal and epithelial part. The printed constructs were evaluated for their microstructure, cell viability and proliferation, and key protein expression (Ki67, p63α, p40, CK3, CK15, collagen type I, VWF). The 3D printed stromal constructs were also implanted into porcine corneal organ cultures. Both cell types maintained good viability after printing. Laser-printed hESC-LESCs showed epithelial cell morphology, expression of Ki67 proliferation marker and co-expression of corneal progenitor markers p63α and p40. Importantly, the printed hESC-LESCs formed a stratified epithelium with apical expression of CK3 and basal expression of the progenitor markers. The structure of the 3D bioprinted stroma demonstrated that the hASCs had organized horizontally as in the native corneal stroma and showed positive labeling for collagen I. After 7 days in porcine organ cultures, the 3D bioprinted

  10. Collagen Fibrils: Nature's Highly Tunable Nonlinear Springs.

    Science.gov (United States)

    Andriotis, Orestis G; Desissaire, Sylvia; Thurner, Philipp J

    2018-03-21

    Tissue hydration is well known to influence tissue mechanics and can be tuned via osmotic pressure. Collagen fibrils are nature's nanoscale building blocks to achieve biomechanical function in a broad range of biological tissues and across many species. Intrafibrillar covalent cross-links have long been thought to play a pivotal role in collagen fibril elasticity, but predominantly at large, far from physiological, strains. Performing nanotensile experiments of collagen fibrils at varying hydration levels by adjusting osmotic pressure in situ during atomic force microscopy experiments, we show the power the intrafibrillar noncovalent interactions have for defining collagen fibril tensile elasticity at low fibril strains. Nanomechanical tensile tests reveal that osmotic pressure increases collagen fibril stiffness up to 24-fold in transverse (nanoindentation) and up to 6-fold in the longitudinal direction (tension), compared to physiological saline in a reversible fashion. We attribute the stiffening to the density and strength of weak intermolecular forces tuned by hydration and hence collagen packing density. This reversible mechanism may be employed by cells to alter their mechanical microenvironment in a reversible manner. The mechanism could also be translated to tissue engineering approaches for customizing scaffold mechanics in spatially resolved fashion, and it may help explain local mechanical changes during development of diseases and inflammation.

  11. Corneal Toxicity Following Exposure to Asclepias Tuberosa

    OpenAIRE

    Mikkelsen, Lauge Hjorth; Hamoudi, Hassan; G?l, Cigdem Altuntas; Heegaard, Steffen

    2017-01-01

    PURPOSE: To present a case of corneal toxicity following exposure to milky plant latex from Asclepias tuberosa.METHODS: A 70-year-old female presented with blurred vision and pain in her left eye after handling an Ascepias tuberosa. Clinical examination revealed a corneal stromal oedema with small epithelial defects. The corneal endothelium was intact and folds in Descemets membrane were observed. The oedema was treated with chloramphenicol, dexamethasone and scopolamine.RESULTS: The corneal ...

  12. Topical Drug Formulations for Prolonged Corneal Anesthesia

    Science.gov (United States)

    Wang, Liqiang; Shankarappa, Sahadev A.; Tong, Rong; Ciolino, Joseph B.; Tsui, Jonathan H.; Chiang, Homer H.; Kohane, Daniel S.

    2013-01-01

    Purpose Ocular local anesthetics (OLA’s) currently used in routine clinical practice for corneal anesthesia are short acting and their ability to delay corneal healing makes them unsuitable for long-term use. In this study, we examined the effect on the duration of corneal anesthesia of the site-1 sodium channel blocker tetrodotoxin (TTX), applied with either proparacaine or the chemical permeation enhancer OTAB. The effect of test solutions on corneal healing was also studied. Methods Solutions of TTX, proparacaine, and OTAB, singly or in combination were applied topically to the rat cornea. The blink response, an indirect measure of corneal sensitivity, was recorded using a Cochet-Bonnet esthesiometer, and the duration of corneal anesthesia calculated. The effect of test compounds on the rate of corneal epithelialization was studied in vivo following corneal debridement. Results Combination of TTX and proparacaine resulted in corneal anesthesia that was 8–10 times longer in duration than that from either drug administered alone, while OTAB did not prolong anesthesia. The rate of corneal healing was moderately delayed following co-administration of TTX and proparacaine. Conclusion Co-administration of TTX and proparacaine significantly prolonged corneal anesthesia but in view of delayed corneal re-epithelialization, caution is suggested in use of the combination. PMID:23615270

  13. Biocompatibility and Biomechanical Effect of Single Wall Carbon Nanotubes Implanted in the Corneal Stroma: A Proof of Concept Investigation

    Directory of Open Access Journals (Sweden)

    Alfredo Vega-Estrada

    2016-01-01

    Full Text Available Corneal ectatic disorders are characterized by a progressive weakening of the tissue due to biomechanical alterations of the corneal collagen fibers. Carbon nanostructures, mainly carbon nanotubes (CNTs and graphene, are nanomaterials that offer extraordinary mechanical properties and are used to increase the rigidity of different materials and biomolecules such as collagen fibers. We conducted an experimental investigation where New Zealand rabbits were treated with a composition of CNTs suspended in balanced saline solution which was applied in the corneal tissue. Biocompatibility of the composition was assessed by means of histopathology analysis and mechanical properties by stress-strain measurements. Histopathology samples stained with blue Alcian showed that there were no fibrous scaring and no alterations in the mucopolysaccharides of the stroma. It also showed that there were no signs of active inflammation. These were confirmed when Masson trichrome staining was performed. Biomechanical evaluation assessed by means of tensile test showed that there is a trend to obtain higher levels of rigidity in those corneas implanted with CNTs, although these changes are not statistically significant (p>0.05. Implanting CNTs is biocompatible and safe procedure for the corneal stroma which can lead to an increase in the rigidity of the collagen fibers.

  14. N-Isopropylacrylamide-co-glycidylmethacrylate as a Thermoresponsive Substrate for Corneal Endothelial Cell Sheet Engineering

    Directory of Open Access Journals (Sweden)

    Bernadette K. Madathil

    2014-01-01

    Full Text Available Endothelial keratoplasty is a recent shift in the surgical treatment of corneal endothelial dystrophies, where the dysfunctional endothelium is replaced whilst retaining the unaffected corneal layers. To overcome the limitation of donor corneal shortage, alternative use of tissue engineered constructs is being researched. Tissue constructs with intact extracellular matrix are generated using stimuli responsive polymers. In this study we evaluated the feasibility of using the thermoresponsive poly(N-isopropylacrylamide-co-glycidylmethacrylate polymer as a culture surface to harvest viable corneal endothelial cell sheets. Incubation below the lower critical solution temperature of the polymer allowed the detachment of the intact endothelial cell sheet. Phase contrast and scanning electron microscopy revealed the intact architecture, cobble stone morphology, and cell-to-cell contact in the retrieved cell sheet. Strong extracellular matrix deposition was also observed. The RT-PCR analysis confirmed functionally active endothelial cells in the cell sheet as evidenced by the positive expression of aquaporin 1, collagen IV, Na+-K+ ATPase, and FLK-1. Na+-K+ ATPase protein expression was also visualized by immunofluorescence staining. These results suggest that the in-house developed thermoresponsive culture dish is a suitable substrate for the generation of intact corneal endothelial cell sheet towards transplantation for endothelial keratoplasty.

  15. Acute corneal hydrops in keratoconus

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    Prafulla K Maharana

    2013-01-01

    Full Text Available Acute corneal hydrops is a condition characterized by stromal edema due to leakage of aqueous through a tear in descemet membrane. The patient presents with sudden onset decrease in vision, photophobia, and pain. Corneal thinning and ectasias combined with trivial trauma to the eye mostly by eye rubbing is considered as the underlying cause. With conservative approach self-resolution takes around 2 to 3 months. Surgical intervention is required in cases of non-resolution of corneal edema to avoid complications and for early visual rehabilitation. Intracameral injection of air or gas such as perflouropropane is the most common surgical procedure done. Recent investigative modality such as anterior segment optical coherence tomography is an extremely useful tool for diagnosis, surgical planning, and postoperative follow up. Resolution of hydrops may improve the contact lens tolerance and visual acuity but most cases require keratoplasty for visual rehabilitation.

  16. Ocular dimensions, corneal thickness, and corneal curvature in quarter horses with hereditary equine regional dermal asthenia.

    Science.gov (United States)

    Badial, Peres R; Cisneros-Àlvarez, Luis Emiliano; Brandão, Cláudia Valéria S; Ranzani, José Joaquim T; Tomaz, Mayana A R V; Machado, Vania M; Borges, Alexandre S

    2015-09-01

    The aim of this study was to compare ocular dimensions, corneal curvature, and corneal thickness between horses affected with hereditary equine regional dermal asthenia (HERDA) and unaffected horses. Five HERDA-affected quarter horses and five healthy control quarter horses were used. Schirmer's tear test, tonometry, and corneal diameter measurements were performed in both eyes of all horses prior to ophthalmologic examinations. Ultrasonic pachymetry was performed to measure the central, temporal, nasal, dorsal, and ventral corneal thicknesses in all horses. B-mode ultrasound scanning was performed on both eyes of each horse to determine the dimensions of the ocular structures and to calculate the corneal curvature. Each corneal region examined in this study was thinner in the affected group compared with the healthy control group. However, significant differences in corneal thickness were only observed for the central and dorsal regions. HERDA-affected horses exhibited significant increases in corneal curvature and corneal diameter compared with unaffected animals. The ophthalmologic examinations revealed mild corneal opacity in one eye of one affected horse and in both eyes of three affected horses. No significant between-group differences were observed for Schirmer's tear test, intraocular pressure, or ocular dimensions. Hereditary equine regional dermal asthenia-affected horses exhibit decreased corneal thickness in several regions of the cornea, increased corneal curvature, increased corneal diameter, and mild corneal opacity. Additional research is required to determine whether the increased corneal curvature significantly impacts the visual accuracy of horses with HERDA. © 2014 American College of Veterinary Ophthalmologists.

  17. Distinct characteristics of mandibular bone collagen relative to long bone collagen: relevance to clinical dentistry.

    Science.gov (United States)

    Matsuura, Takashi; Tokutomi, Kentaro; Sasaki, Michiko; Katafuchi, Michitsuna; Mizumachi, Emiri; Sato, Hironobu

    2014-01-01

    Bone undergoes constant remodeling throughout life. The cellular and biochemical mechanisms of bone remodeling vary in a region-specific manner. There are a number of notable differences between the mandible and long bones, including developmental origin, osteogenic potential of mesenchymal stem cells, and the rate of bone turnover. Collagen, the most abundant matrix protein in bone, is responsible for determining the relative strength of particular bones. Posttranslational modifications of collagen, such as intermolecular crosslinking and lysine hydroxylation, are the most essential determinants of bone strength, although the amount of collagen is also important. In comparison to long bones, the mandible has greater collagen content, a lower amount of mature crosslinks, and a lower extent of lysine hydroxylation. The great abundance of immature crosslinks in mandibular collagen suggests that there is a lower rate of cross-link maturation. This means that mandibular collagen is relatively immature and thus more readily undergoes degradation and turnover. The greater rate of remodeling in mandibular collagen likely renders more flexibility to the bone and leaves it more suited to constant exercise. As reviewed here, it is important in clinical dentistry to understand the distinctive features of the bones of the jaw.

  18. Distinct Characteristics of Mandibular Bone Collagen Relative to Long Bone Collagen: Relevance to Clinical Dentistry

    Directory of Open Access Journals (Sweden)

    Takashi Matsuura

    2014-01-01

    Full Text Available Bone undergoes constant remodeling throughout life. The cellular and biochemical mechanisms of bone remodeling vary in a region-specific manner. There are a number of notable differences between the mandible and long bones, including developmental origin, osteogenic potential of mesenchymal stem cells, and the rate of bone turnover. Collagen, the most abundant matrix protein in bone, is responsible for determining the relative strength of particular bones. Posttranslational modifications of collagen, such as intermolecular crosslinking and lysine hydroxylation, are the most essential determinants of bone strength, although the amount of collagen is also important. In comparison to long bones, the mandible has greater collagen content, a lower amount of mature crosslinks, and a lower extent of lysine hydroxylation. The great abundance of immature crosslinks in mandibular collagen suggests that there is a lower rate of cross-link maturation. This means that mandibular collagen is relatively immature and thus more readily undergoes degradation and turnover. The greater rate of remodeling in mandibular collagen likely renders more flexibility to the bone and leaves it more suited to constant exercise. As reviewed here, it is important in clinical dentistry to understand the distinctive features of the bones of the jaw.

  19. Corneal manifestations in systemic diseases

    OpenAIRE

    Zarranz-Ventura, J.; Nova, E. De; Moreno-Montañés, J.

    2008-01-01

    Un gran número de enfermedades sistémicas presentan manifestaciones corneales dentro de su espectro de enfermedad. El estudio detallado de todos los cuadros que asocian patología corneal resulta inabarcable, por ello se presentan las enfermedades más prevalentes o características. Este estudio contempla las enfermedades pulmonares y conectivopatías (colagenosis, enfermedades reumatológicas y enfermedades inflamatorias idiopáticas), las enfermedades dermatológicas, cardiovasculares, hematológi...

  20. [Corneal manifestations in systemic diseases].

    Science.gov (United States)

    Zarranz Ventura, J; De Nova, E; Moreno-Montañés, J

    2008-01-01

    Systemic diseases affecting the cornea have a wide range of manifestations. The detailed study of all pathologies that cause corneal alteration is unapproachable, so we have centered our interest in the most prevalent or characteristic of them. In this paper we have divided these pathologies in sections to facilitate their study. Pulmonar and conective tissue (like colagen, rheumatologic and idiopathic inflamatory diseases), dermatologic, cardiovascular, hematologic, digestive and hepatopancreatic diseases with corneal alteration are described. Endocrine and metabolic diseases, malnutrition and carential states are also studied, as well as some otorhinolaryngologic and genetic diseases that affect the cornea. Finally, a brief report of ocular toxicity induced by drugs is referred.

  1. Progress in corneal wound healing

    Science.gov (United States)

    Ljubimov, Alexander V.; Saghizadeh, Mehrnoosh

    2015-01-01

    Corneal wound healing is a complex process involving cell death, migration, proliferation, differentiation, and extracellular matrix remodeling. Many similarities are observed in the healing processes of corneal epithelial, stromal and endothelial cells, as well as cell-specific differences. Corneal epithelial healing largely depends on limbal stem cells and remodeling of the basement membrane. During stromal healing, keratocytes get transformed to motile and contractile myofibroblasts largely due to activation of transforming growth factor-β system. Endothelial cells heal mostly by migration and spreading, with cell proliferation playing a secondary role. In the last decade, many aspects of wound healing process in different parts of the cornea have been elucidated, and some new therapeutic approaches have emerged. The concept of limbal stem cells received rigorous experimental corroboration, with new markers uncovered and new treatment options including gene and microRNA therapy tested in experimental systems. Transplantation of limbal stem cell-enriched cultures for efficient re-epithelialization in stem cell deficiency and corneal injuries has become reality in clinical setting. Mediators and course of events during stromal healing have been detailed, and new treatment regimens including gene (decorin) and stem cell therapy for excessive healing have been designed. This is a very important advance given the popularity of various refractive surgeries entailing stromal wound healing. Successful surgical ways of replacing the diseased endothelium have been clinically tested, and new approaches to accelerate endothelial healing and suppress endothelial-mesenchymal transformation have been proposed including Rho kinase (ROCK) inhibitor eye drops and gene therapy to activate TGF-β inhibitor SMAD7. Promising new technologies with potential for corneal wound healing manipulation including microRNA, induced pluripotent stem cells to generate corneal epithelium, and

  2. Correlations between corneal and total wavefront aberrations

    Science.gov (United States)

    Mrochen, Michael; Jankov, Mirko; Bueeler, Michael; Seiler, Theo

    2002-06-01

    Purpose: Corneal topography data expressed as corneal aberrations are frequently used to report corneal laser surgery results. However, the optical image quality at the retina depends on all optical elements of the eye such as the human lens. Thus, the aim of this study was to investigate the correlations between the corneal and total wavefront aberrations and to discuss the importance of corneal aberrations for representing corneal laser surgery results. Methods: Thirty three eyes of 22 myopic subjects were measured with a corneal topography system and a Tschernig-type wavefront analyzer after the pupils were dilated to at least 6 mm in diameter. All measurements were centered with respect to the line of sight. Corneal and total wavefront aberrations were calculated up to the 6th Zernike order in the same reference plane. Results: Statistically significant correlations (p the corneal and total wavefront aberrations were found for the astigmatism (C3,C5) and all 3rd Zernike order coefficients such as coma (C7,C8). No statistically significant correlations were found for all 4th to 6th order Zernike coefficients except for the 5th order horizontal coma C18 (p equals 0.003). On average, all Zernike coefficients for the corneal aberrations were found to be larger compared to Zernike coefficients for the total wavefront aberrations. Conclusions: Corneal aberrations are only of limited use for representing the optical quality of the human eye after corneal laser surgery. This is due to the lack of correlation between corneal and total wavefront aberrations in most of the higher order aberrations. Besides this, the data present in this study yield towards an aberration balancing between corneal aberrations and the optical elements within the eye that reduces the aberration from the cornea by a certain degree. Consequently, ideal customized ablations have to take both, corneal and total wavefront aberrations, into consideration.

  3. Investigation of Overrun-Processed Porous Hyaluronic Acid Carriers in Corneal Endothelial Tissue Engineering.

    Directory of Open Access Journals (Sweden)

    Jui-Yang Lai

    Full Text Available Hyaluronic acid (HA is a linear polysaccharide naturally found in the eye and therefore is one of the most promising biomaterials for corneal endothelial regenerative medicine. This study reports, for the first time, the development of overrun-processed porous HA hydrogels for corneal endothelial cell (CEC sheet transplantation and tissue engineering applications. The hydrogel carriers were characterized to examine their structures and functions. Evaluations of carbodiimide cross-linked air-dried and freeze-dried HA samples were conducted simultaneously for comparison. The results indicated that during the fabrication of freeze-dried HA discs, a technique of introducing gas bubbles in the aqueous biopolymer solutions can be used to enlarge pore structure and prevent dense surface skin formation. Among all the groups studied, the overrun-processed porous HA carriers show the greatest biological stability, the highest freezable water content and glucose permeability, and the minimized adverse effects on ionic pump function of rabbit CECs. After transfer and attachment of bioengineered CEC sheets to the overrun-processed HA hydrogel carriers, the therapeutic efficacy of cell/biopolymer constructs was tested using a rabbit model with corneal endothelial dysfunction. Clinical observations including slit-lamp biomicroscopy, specular microscopy, and corneal thickness measurements showed that the construct implants can regenerate corneal endothelium and restore corneal transparency at 4 weeks postoperatively. Our findings suggest that cell sheet transplantation using overrun-processed porous HA hydrogels offers a new way to reconstruct the posterior corneal surface and improve endothelial tissue function.

  4. Collagen Quantification in Tissue Specimens.

    Science.gov (United States)

    Coentro, João Quintas; Capella-Monsonís, Héctor; Graceffa, Valeria; Wu, Zhuning; Mullen, Anne Maria; Raghunath, Michael; Zeugolis, Dimitrios I

    2017-01-01

    Collagen is the major extracellular protein in mammals. Accurate quantification of collagen is essential in the biomaterials (e.g., reproducible collagen scaffold fabrication), drug discovery (e.g., assessment of collagen in pathophysiologies, such as fibrosis), and tissue engineering (e.g., quantification of cell-synthesized collagen) fields. Although measuring hydroxyproline content is the most widely used method to quantify collagen in biological specimens, the process is very laborious. To this end, the Sircol™ Collagen Assay is widely used due to its inherent simplicity and convenience. However, this method leads to overestimation of collagen content due to the interaction of Sirius red with basic amino acids of non-collagenous proteins. Herein, we describe the addition of an ultrafiltration purification step in the process to accurately determine collagen content in tissues.

  5. The effects of different cross-linking conditions on collagen-based nanocomposite scaffolds-an in vitro evaluation using mesenchymal stem cells

    Czech Academy of Sciences Publication Activity Database

    Suchý, Tomáš; Šupová, Monika; Sauerová, P.; Verdánová, M.; Sucharda, Zbyněk; Rýglová, Šárka; Žaloudková, Margit; Sedláček, R.; Hubálek Kalbáčová, M.

    2015-01-01

    Roč. 10, DEC (2015), č. článku 065008. ISSN 1748-6041 R&D Projects: GA MZd(CZ) NV15-25813A Institutional support: RVO:67985891 Keywords : cross-linking agents * nano-composite scaffolds * human mesenchymal stem cells * EDC/NHS * genipin Subject RIV: JI - Composite Materials Impact factor: 3.361, year: 2015

  6. Collagen crosslinking for ectasia following PRK performed in excimer laser-assisted keratoplasty for keratoconus.

    Science.gov (United States)

    Spadea, Leopoldo

    2012-01-01

    To report the results of corneal collagen crosslinking (CXL) in a patient with corneal ectasia developed after excimer laser-assisted lamellar keratoplasty for keratoconus and a secondary photorefractive keratectomy (PRK) for residual refractive error. A 33-year-old woman, who had originally been treated for keratoconus in the right eye by excimer laser-assisted lamellar keratoplasty, subsequently had her residual ametropia treated by topographically guided, transepithelial excimer laser PRK. Five years after PRK, the patient developed corneal ectasia showing concomitant visual changes of best spectacle-corrected visual acuity (BSCVA) reduced to 20/33 with a refraction of -6.00 +6.00 × 30. The minimum corneal thickness at the ectasia apex was 406 µm. A treatment of riboflavin-UVA-induced corneal CXL was performed on the right eye. Two years after the CXL treatment, the right eye improved to 20/20 BSCVA with a refraction of plano +1.00 × 50 while exhibiting a clear lamellar graft. Corneal CXL provided safe and effective management of ectasia developed after excimer laser-assisted lamellar keratoplasty and PRK.

  7. The Impact of Pterygium Excision on Corneal Astigmatism

    International Nuclear Information System (INIS)

    Khan, F. A.; Niazi, S. P. K.; Khan, D. A.

    2014-01-01

    Objective: To compare the corneal astigmatism before and after the excision of pterygium and also to determine the correlation of pterygium size with the postoperative corneal astigmatism. Study Design: Cross-sectional interventional study. Place and Duration of Study: Eye Department, Combined Military Hospital, Abbottabad, from May 2011 to March 2012. Methodology: Thirty patients underwent pterygium excision. Pre-operatively Snellen visual acuity, manifest refraction and slit lamp examination was done. The size of the pterygium was recorded in mm by projecting a horizontal slit lamp beam from the limbus to the apex. All the pterygium were equal to or greater than 2.5 mm. Keratometry was performed with an automated keratometer. Keratometric data was recorded pre-operatively and at 28 days postoperatively. Wilcoxon signed rank test was used for comparing the pre-operative and the postoperative corneal astigmatism. Spearman's rank order was calculated to observe correlation of pterygium size with the postoperative astigmatism. Results: The median (mean rank) pre-operative astigmatism of 2.25 (15.50) reduced to a median (mean rank) postoperative astigmatism of 1.30 (14.96). This decrease in the postoperative astigmatism was statistically significant (p < 0.001). There was a statistically non-significant correlation between the postoperative astigmatism and the pterygium size (rs = -0.29, p = 0.12). Conclusion: Pterygium excision caused significant reduction in corneal astigmatism. (author)

  8. Corneal densitometry and its correlation with age, pachymetry, corneal curvature, and refraction.

    Science.gov (United States)

    Garzón, Nuria; Poyales, Francisco; Illarramendi, Igor; Mendicute, Javier; Jáñez, Óscar; Caro, Pedro; López, Alfredo; Argüeso, Francisco

    2017-12-01

    To determine normative corneal densitometry values in relation to age, sex, refractive error, corneal thickness, and keratometry, measured using the Oculus Pentacam system. Three hundred and thirty-eight healthy subjects (185 men; 153 women) with no corneal disease underwent an exhaustive ocular examination. Corneal densitometry was expressed in standardized grayscale units (GSU). The mean corneal densitometry over the total area was 16.46 ± 1.85 GSU. The Pearson correlation coefficient for total densitometry was r = 0.542 (p  0.05). This is the first report of normative corneal densitometry values in relation to keratometry, corneal thickness, and spherical equivalent measured with the latest Oculus Pentacam software. Corneal densitometry increases with age, but corneal keratometry and refractive parameters do not affect light scattering in the human cornea.

  9. Corneal Regeneration After Photorefractive Keratectomy: A Review

    Directory of Open Access Journals (Sweden)

    Javier Tomás-Juan

    2015-07-01

    Full Text Available Photorefractive keratectomy (PRK remodels corneal stroma to compensate refractive errors. The removal of epithelium and the ablation of stroma provoke the disruption of corneal nerves and a release of several peptides from tears, epithelium, stroma and nerves. A myriad of cytokines, growth factors, and matrix metalloproteases participate in the process of corneal wound healing. Their balance will determine if reepithelization and stromal remodeling are appropriate. The final aim is to achieve corneal transparency for restoring corneal function, and a proper visual quality. Therefore, wound-healing response is critical for a successful refractive surgery. Our goal is to provide an overview into how corneal wounding develops following PRK. We will also review the influence of intraoperative application of mitomycin C, bandage contact lenses, anti-inflammatory and other drugs in preventing corneal haze and post-PRK pain.

  10. History of corneal transplantation in Australia.

    Science.gov (United States)

    Coster, Douglas J

    2015-04-01

    Corneal transplantation is a triumph of modern ophthalmology. The possibility of corneal transplantation was first raised in 1797 but a century passed before Zirm achieved the first successful penetrating graft in 1905. Gibson reported the first corneal graft in Australia from Brisbane in 1940 and English established the first eye bank there a few years later. Corneal transplantation evolved steadily over the twentieth century. In the second half of the century, developments in microsurgery, including surgical materials such as monofilament nylon and strong topical steroid drops, accounted for improvements in outcomes. In 2013, approximately 1500 corneal transplants were done in Australia. Eye banking has evolved to cope with the rising demands for donor corneas. Australian corneal surgeons collaborated to establish and support the Australian Corneal Graft Registry in 1985. It follows the outcomes of their surgery and has become an important international resource for surgeons seeking further improvement with the procedure. © 2014 Royal Australian and New Zealand College of Ophthalmologists.

  11. Corneal Regeneration After Photorefractive Keratectomy: A Review.

    Science.gov (United States)

    Tomás-Juan, Javier; Murueta-Goyena Larrañaga, Ane; Hanneken, Ludger

    2015-01-01

    Photorefractive keratectomy (PRK) remodels corneal stroma to compensate refractive errors. The removal of epithelium and the ablation of stroma provoke the disruption of corneal nerves and a release of several peptides from tears, epithelium, stroma and nerves. A myriad of cytokines, growth factors, and matrix metalloproteases participate in the process of corneal wound healing. Their balance will determine if reepithelization and stromal remodeling are appropriate. The final aim is to achieve corneal transparency for restoring corneal function, and a proper visual quality. Therefore, wound-healing response is critical for a successful refractive surgery. Our goal is to provide an overview into how corneal wounding develops following PRK. We will also review the influence of intraoperative application of mitomycin C, bandage contact lenses, anti-inflammatory and other drugs in preventing corneal haze and post-PRK pain. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  12. Corneal stroma microfibrils.

    Science.gov (United States)

    Hanlon, Samuel D; Behzad, Ali R; Sakai, Lynn Y; Burns, Alan R

    2015-03-01

    Elastic tissue was first described well over a hundred years ago and has since been identified in nearly every part of the body. In this review, we examine elastic tissue in the corneal stroma with some mention of other ocular structures which have been more thoroughly described in the past. True elastic fibers consist of an elastin core surrounded by fibrillin microfibrils. However, the presence of elastin fibers is not a requirement and some elastic tissue is comprised of non-elastin-containing bundles of microfibrils. Fibers containing a higher relative amount of elastin are associated with greater elasticity and those without elastin, with structural support. Recently it has been shown that the microfibrils, not only serve mechanical roles, but are also involved in cell signaling through force transduction and the release of TGF-β. A well characterized example of elastin-free microfibril bundles (EFMBs) is found in the ciliary zonules which suspend the crystalline lens in the eye. Through contraction of the ciliary muscle they exert enough force to reshape the lens and thereby change its focal point. It is believed that the molecules comprising these fibers do not turn-over and yet retain their tensile strength for the life of the animal. The mechanical properties of the cornea (strength, elasticity, resiliency) would suggest that EFMBs are present there as well. However, many authors have reported that, although present during embryonic and early postnatal development, EFMBs are generally not present in adults. Serial-block-face imaging with a scanning electron microscope enabled 3D reconstruction of elements in murine corneas. Among these elements were found fibers that formed an extensive network throughout the cornea. In single sections these fibers appeared as electron dense patches. Transmission electron microscopy provided additional detail of these patches and showed them to be composed of fibrils (∼10 nm diameter). Immunogold evidence clearly

  13. Corneal stroma microfibrils

    KAUST Repository

    Hanlon, Samuel D.

    2015-03-01

    Elastic tissue was first described well over a hundred years ago and has since been identified in nearly every part of the body. In this review, we examine elastic tissue in the corneal stroma with some mention of other ocular structures which have been more thoroughly described in the past. True elastic fibers consist of an elastin core surrounded by fibrillin microfibrils. However, the presence of elastin fibers is not a requirement and some elastic tissue is comprised of non-elastin-containing bundles of microfibrils. Fibers containing a higher relative amount of elastin are associated with greater elasticity and those without elastin, with structural support. Recently it has been shown that the microfibrils, not only serve mechanical roles, but are also involved in cell signaling through force transduction and the release of TGF-β. A well characterized example of elastin-free microfibril bundles (EFMBs) is found in the ciliary zonules which suspend the crystalline lens in the eye. Through contraction of the ciliary muscle they exert enough force to reshape the lens and thereby change its focal point. It is believed that the molecules comprising these fibers do not turn-over and yet retain their tensile strength for the life of the animal. The mechanical properties of the cornea (strength, elasticity, resiliency) would suggest that EFMBs are present there as well. However, many authors have reported that, although present during embryonic and early postnatal development, EFMBs are generally not present in adults. Serial-block-face imaging with a scanning electron microscope enabled 3D reconstruction of elements in murine corneas. Among these elements were found fibers that formed an extensive network throughout the cornea. In single sections these fibers appeared as electron dense patches. Transmission electron microscopy provided additional detail of these patches and showed them to be composed of fibrils (~10nm diameter). Immunogold evidence clearly

  14. Corneal thickness: measurement and implications.

    Science.gov (United States)

    Ehlers, Niels; Hjortdal, Jesper

    2004-03-01

    The thickness of the cornea was reported in more than 100-year-old textbooks on physiological optics (Helmholtz, Gullstrand). Physiological interest was revived in the 1950s by David Maurice, and over the next 50 years, this 'simple' biological parameter has been studied extensively. Several techniques for its measurement have been described and physiological and clinical significance have been studied. In this review, the different methods and techniques of measurement are briefly presented (optical, ultrasound). While the corneal thickness of many animals are the same over a considerable part of the surface, in the human cornea anterior and posterior curvature are not concentric giving rise to a problem of definition. Based on this the precision and accuracy of determining the central corneal thickness are discussed. Changes in corneal thickness reflects changes in function of the boundary layers, in particular the endothelial barrier. The absolute value of thickness is of importance for the estimation of IOP but also in diagnosis of corneal and systemic disorders. Finally it is discussed to what extent the thickness is a biometric parameter of significance, e.g. in the progression of myopia or in the development of retinal detachment.

  15. Interference figures of polarimetric interferometry analysis of the human corneal stroma.

    Directory of Open Access Journals (Sweden)

    Rodolfo Mastropasqua

    Full Text Available A rotating polarimetric 90°-cross linear-filter interferometry system was used to detect the morphological characteristics and features of interference patterns produced in in-vivo corneal stroma in healthy human corneas of 23 subjects. The characteristic corneal isogyres presenting with an evident cross-shaped pattern, grossly aligned with the fixation axis, were observed in all patients with centers within the pupillary dark area, impeding the exact determination of the center point. During the rotational scan in 78.3% of the eyes the cross-shaped pattern of the isogyre gradually separated to form two distinct hyperbolic arcs in opposite quadrants, reaching their maximal separation at 45 degrees with respect to angle of cross-shaped pattern formation. The corneal cross and hyperbolic-pattern repeated every 90° throughout the 360° rotational scan. While the interpretation of the isogyres presents particular difficulties, two summary parameters can be extracted for each cornea: the presence/orientation of a single or two dark areas in post-processed images and isochromes. However, the development of dedicated software for semi-quantitative analysis of these parameters and enantiomorphism may become available in the near future. The possible application of polarimetric interferometry in the field of both corneal pathologies and corneal surgery may be of great interest for clinical purposes.

  16. Management of corneal bee sting

    Directory of Open Access Journals (Sweden)

    Razmjoo H

    2011-12-01

    Full Text Available Hassan Razmjoo1,2, Mohammad-Ali Abtahi1,2,4, Peyman Roomizadeh1,3, Zahra Mohammadi1,2, Seyed-Hossein Abtahi1,3,41Medical School, Isfahan University of Medical Sciences (IUMS; 2Ophthalmology Ward, Feiz Hospital, IUMS; 3Isfahan Medical Students Research Center (IMSRC, IUMS; 4Isfahan Ophthalmology Research Center (IORC, Feiz Hospital, IUMS, Isfahan, IranAbstract: Corneal bee sting is an uncommon environmental eye injury that can result in various ocular complications with an etiology of penetrating, immunologic, and toxic effects of the stinger and its injected venom. In this study we present our experience in the management of a middle-aged male with a right-sided deep corneal bee sting. On arrival, the patient was complaining of severe pain, blurry vision with acuity of 160/200, and tearing, which he had experienced soon after the injury. Firstly, we administered conventional drugs for eye injuries, including topical antibiotic, corticosteroid, and cycloplegic agents. After 2 days, corneal stromal infiltration and edema developed around the site of the sting, and visual acuity decreased to 100/200. These conditions led us to remove the stinger surgically. Within 25 days of follow-up, the corneal infiltration decreased gradually, and visual acuity improved to 180/200. We suggest a two-stage management approach for cases of corneal sting. For the first stage, if the stinger is readily accessible or primary dramatic reactions, including infiltration, especially on the visual axis, exist, manual or surgical removal would be indicated. Otherwise, we recommend conventional treatments for eye injuries. Given this situation, patients should be closely monitored for detection of any worsening. If the condition does not resolve or even deteriorates, for the second stage, surgical removal of the stinger under local or generalized anesthesia is indicated.Keywords: bee sting, stinger, cornea, removal, management, surgery

  17. Surface Topography and Mechanical Strain Promote Keratocyte Phenotype and Extracellular Matrix Formation in a Biomimetic 3D Corneal Model.

    Science.gov (United States)

    Zhang, Wei; Chen, Jialin; Backman, Ludvig J; Malm, Adam D; Danielson, Patrik

    2017-03-01

    The optimal functionality of the native corneal stroma is mainly dependent on the well-ordered arrangement of extracellular matrix (ECM) and the pressurized structure. In order to develop an in vitro corneal model, it is crucial to mimic the in vivo microenvironment of the cornea. In this study, the influence of surface topography and mechanical strain on keratocyte phenotype and ECM formation within a biomimetic 3D corneal model is studied. By modifying the surface topography of materials, it is found that patterned silk fibroin film with 600 grooves mm -1 optimally supports cell alignment and ECM arrangement. Furthermore, treatment with 3% dome-shaped mechanical strain, which resembles the shape and mechanics of native cornea, significantly enhances the expression of keratocyte markers as compared to flat-shaped strain. Accordingly, a biomimetic 3D corneal model, in the form of a collagen-modified, silk fibroin-patterned construct subjected to 3% dome-shaped strain, is created. Compared to traditional 2D cultures, it supports a significantly higher expression of keratocyte and ECM markers, and in conclusion better maintains keratocyte phenotype, alignment, and fusiform cell shape. Therefore, the novel biomimetic 3D corneal model developed in this study serves as a useful in vitro 3D culture model to improve current 2D cultures for corneal studies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Central corneal thickness and related factors in an elderly American Chinese population.

    Science.gov (United States)

    Wang, Dandan; Singh, Kuldev; Weinreb, Robert; Kempen, John; He, Mingguang; Lin, Shan

    2011-07-01

    To assess central corneal thickness and related factors in an elderly American Chinese population residing in San Francisco. Cross-sectional community based study. American Chinese aged 40 years and older were enrolled using random cluster sampling and volunteer screening in the Chinatown district of San Francisco. The following data were obtained: central corneal thickness by ultrasound pachymetry, intraocular pressure by Goldmann applanation tonometry, axial length by A-scan biometry, refractive status and corneal curvature by autorefractor. History of systemic and ocular diseases was collected via standard questionnaire. Central corneal thickness. Of 311 eligible subjects, 274 consented to study participation, and 228 phakic eyes were analyzed. Mean corneal thickness was 524.1 ± 31.1 µm, 545.5 ± 30.9 µm and 538.9 ± 31.8 µm in the sampling cluster, volunteer group and all subjects, respectively. A multiple linear regression model showed corneal thickness to be negatively associated with age (standardized regression coefficient [SRC] = -0.21; P = 0.016) and corneal curvature (SRC = -0.19; P = 0.018) but positively correlated with intraocular pressure (SRC = 0.20; P = 0.023). The distribution of central corneal thickness among this American Chinese population is similar to that reported in studies from East Asia. The independent factors associated with thinner corneas included older age, lower intraocular pressure and greater corneal curvature. While descendents of Chinese immigrants in America have, on average, thicker corneas than their ancestors, this phenomenon is potentially impacted by the level of intraocular pressure. © 2011 The Authors. Clinical and Experimental Ophthalmology © 2011 Royal Australian and New Zealand College of Ophthalmologists.

  19. Enhancing amine terminals in an amine-deprived collagen matrix.

    LENUS (Irish Health Repository)

    Tiong, William H C

    2008-10-21

    Collagen, though widely used as a core biomaterial in many clinical applications, is often limited by its rapid degradability which prevents full exploitation of its potential in vivo. Polyamidoamine (PAMAM) dendrimer, a highly branched macromolecule, possesses versatile multiterminal amine surface groups that enable them to be tethered to collagen molecules and enhance their potential. In this study, we hypothesized that incorporation of PAMAM dendrimer in a collagen matrix through cross-linking will result in a durable, cross-linked collagen biomaterial with free -NH 2 groups available for further multi-biomolecular tethering. The aim of this study was to assess the physicochemical properties of a G1 PAMAM cross-linked collagen matrix and its cellular sustainability in vitro. Different amounts of G1 PAMAM dendrimer (5 or 10 mg) were integrated into bovine-derived collagen matrices through a cross-linking process, mediated by 5 or 25 mM 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) in 5 mM N-hydroxysuccinimide (NHS) and 50 mM 2-morpholinoethane sulfonic acid buffer at pH 5.5. The physicochemical properties of resultant matrices were investigated with scanning electron microscopy (SEM), collagenase degradation assay, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectra, and ninhydrin assay. Cellular sustainability of the matrices was assessed with Alamar Blue assay and SEM. There was no significant difference in cellular behavior between the treated and nontreated groups. However, the benefit of incorporating PAMAM in the cross-linking reaction was limited when higher concentrations of either agent were used. These results confirm the hypothesis that PAMAM dendrimer can be incorporated in the collagen cross-linking process in order to modulate the properties of the resulting cross-linked collagen biomaterial with free -NH 2 groups available for multi-biomolecular tethering.

  20. Fish collagen is an important panallergen in the Japanese population.

    Science.gov (United States)

    Kobayashi, Y; Akiyama, H; Huge, J; Kubota, H; Chikazawa, S; Satoh, T; Miyake, T; Uhara, H; Okuyama, R; Nakagawara, R; Aihara, M; Hamada-Sato, N

    2016-05-01

    Collagen was identified as a fish allergen in early 2000s. Although its allergenic potential has been suggested to be low, risks associated with collagen as a fish allergen have not been evaluated to a greater extent. In this study, we aimed to clarify the importance of collagen as a fish allergen. Our results showed that 50% of Japanese patients with fish allergy had immunoglobulin E (IgE) against mackerel collagen, whereas 44% had IgE against mackerel parvalbumin. IgE inhibition assay revealed high cross-reactivity of mackerel collagen to 22 fish species (inhibition rates: 87-98%). Furthermore, a recently developed allergy test demonstrated that collagen triggered IgE cross-linking on mast cells. These data indicate that fish collagen is an important and very common panallergen in fish consumed in Japan. The high rate of individuals' collagen allergy may be attributable to the traditional Japanese custom of raw fish consumption. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Turning the tide of corneal blindness

    Directory of Open Access Journals (Sweden)

    Matthew S Oliva

    2012-01-01

    Full Text Available Corneal diseases represent the second leading cause of blindness in most developing world countries. Worldwide, major investments in public health infrastructure and primary eye care services have built a strong foundation for preventing future corneal blindness. However, there are an estimated 4.9 million bilaterally corneal blind persons worldwide who could potentially have their sight restored through corneal transplantation. Traditionally, barriers to increased corneal transplantation have been daunting, with limited tissue availability and lack of trained corneal surgeons making widespread keratoplasty services cost prohibitive and logistically unfeasible. The ascendancy of cataract surgical rates and more robust eye care infrastructure of several Asian and African countries now provide a solid base from which to dramatically expand corneal transplantation rates. India emerges as a clear global priority as it has the world′s largest corneal blind population and strong infrastructural readiness to rapidly scale its keratoplasty numbers. Technological modernization of the eye bank infrastructure must follow suit. Two key factors are the development of professional eye bank managers and the establishment of Hospital Cornea Recovery Programs. Recent adaptation of these modern eye banking models in India have led to corresponding high growth rates in the procurement of transplantable tissues, improved utilization rates, operating efficiency realization, and increased financial sustainability. The widespread adaptation of lamellar keratoplasty techniques also holds promise to improve corneal transplant success rates. The global ophthalmic community is now poised to scale up widespread access to corneal transplantation to meet the needs of the millions who are currently blind.

  2. Clinical applications of corneal confocal microscopy

    Directory of Open Access Journals (Sweden)

    Mitra Tavakoli

    2008-06-01

    Full Text Available Mitra Tavakoli1, Parwez Hossain2, Rayaz A Malik11Division of Cardiovascular Medicine, University of Manchester and Manchester Royal Infirmary, Manchester, UK; 2University of Southampton, Southampton Eye Unit, Southampton General Hospital, Southampton, UKAbstract: Corneal confocal microscopy is a novel clinical technique for the study of corneal cellular structure. It provides images which are comparable to in-vitro histochemical techniques delineating corneal epithelium, Bowman’s layer, stroma, Descemet’s membrane and the corneal endothelium. Because, corneal confocal microscopy is a non invasive technique for in vivo imaging of the living cornea it has huge clinical potential to investigate numerous corneal diseases. Thus far it has been used in the detection and management of pathologic and infectious conditions, corneal dystrophies and ecstasies, monitoring contact lens induced corneal changes and for pre and post surgical evaluation (PRK, LASIK and LASEK, flap evaluations and Radial Keratotomy, and penetrating keratoplasty. Most recently it has been used as a surrogate for peripheral nerve damage in a variety of peripheral neuropathies and may have potential in acting as a surrogate marker for endothelial abnormalities.Keywords: corneal confocal microscopy, cornea, infective keratitis, corneal dystrophy, neuropathy

  3. Comparison of Corneal Biomechanical Properties between Indian and Chinese Adults.

    Science.gov (United States)

    Chua, Jacqueline; Nongpiur, Monisha E; Zhao, Wanting; Tham, Yih Chung; Gupta, Preeti; Sabanayagam, Charumathi; Aung, Tin; Wong, Tien Yin; Cheng, Ching-Yu

    2017-09-01

    To investigate the difference in corneal hysteresis (CH) and corneal resistance factor (CRF) between Indian and Chinese populations. Population-based cross-sectional study. Three hundred eighty-two Singaporean Indian persons and 764 Singaporean Chinese 50 years of age or older were included from the Singapore Indian Eye Study and Singapore Chinese Eye Study, respectively. Participants underwent standardized systemic and ocular examinations and interviewer-administered questionnaires for risk factor assessment. The CH and CRF were measured with the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, NY). Information on genetic ancestry was derived using principal component analysis. Linear regression models were used to investigate the association of CH and CRF with potential risk factors. Corneal hysteresis and CRF. After excluding participants with a history of intraocular surgery, a diagnosis of glaucoma suspect or glaucoma, refractive surgery, or presence of corneal abnormalities, CH and CRF readings were available for 382 Indian persons. For each Indian participant, 2 Chinese participants were selected and matched for age and gender (n = 764). There were no differences in the clinical measurements of CH (10.6±1.6 mmHg; P = 0.670) or CRF (10.3±1.7 mmHg; P = 0.103) between the ethnic groups. However, after adjusting for covariates, Indian persons had, on average, 0.18-mmHg higher CH levels than in Chinese (95% confidence interval [CI], 0.02-0.38; P = 0.031). Consistently, CH level was correlated significantly with genetic ancestry in the Southeast Asian population. Corneal resistance factor level was not associated independently with self-reported ethnicity (95% CI, -0.10 to 0.29; P = 0.335). Chinese have lower CH than Indian persons, and this disparity may reflect biomechanical differences of the cornea. Copyright © 2017 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  4. Assessment of corneal epithelial thickness in dry eye patients.

    Science.gov (United States)

    Cui, Xinhan; Hong, Jiaxu; Wang, Fei; Deng, Sophie X; Yang, Yujing; Zhu, Xiaoyu; Wu, Dan; Zhao, Yujin; Xu, Jianjiang

    2014-12-01

    To investigate the features of corneal epithelial thickness topography with Fourier-domain optical coherence tomography (OCT) in dry eye patients. In this cross-sectional study, 100 symptomatic dry eye patients and 35 normal subjects were enrolled. All participants answered the ocular surface disease index questionnaire and were subjected to OCT, corneal fluorescein staining, tear breakup time, Schirmer 1 test without anesthetic (S1t), and meibomian morphology. Several epithelium statistics for each eye, including central, superior, inferior, minimum, maximum, minimum - maximum, and map standard deviation, were averaged. Correlations of epithelial thickness with the symptoms of dry eye were calculated. The mean (±SD) central, superior, and inferior corneal epithelial thickness was 53.57 (±3.31) μm, 52.00 (±3.39) μm, and 53.03 (±3.67) μm in normal eyes and 52.71 (±2.83) μm, 50.58 (±3.44) μm, and 52.53 (±3.36) μm in dry eyes, respectively. The superior corneal epithelium was thinner in dry eye patients compared with normal subjects (p = 0.037), whereas central and inferior epithelium were not statistically different. In the dry eye group, patients with higher severity grades had thinner superior (p = 0.017) and minimum (p dry eye corneal epithelium was thinner than normal eyes in the superior region. In more severe dry eye disease patients, the superior and minimum epithelium was much thinner, with a greater range of map standard deviation.

  5. A Case of “en bloc” Excision of a Chest Wall Leiomyosarcoma and Closure of the Defect with Non-Cross-Linked Collagen Matrix (Egis®

    Directory of Open Access Journals (Sweden)

    Marco Rastrelli

    2016-10-01

    Full Text Available Sarcomas arising from the chest wall account for less than 20% of all soft tissue sarcomas, and at this site, primitive tumors are the most frequent to occur. Leiomyosarcoma is a malignant smooth muscle tumor and the best outcomes are achieved with wide surgical excision. Although advancements have been made in treatment protocols, leiomyosarcoma remains one of the more difficult soft tissue sarcoma to treat. Currently, general local control is obtained with surgical treatment with wide negative margins. We describe the case of a 50-year-old man who underwent a chest wall resection involving a wide portion of the pectoralis major and minor muscle, the serratus and part of the second, third and fourth ribs of the left side. The full-thickness chest wall defect of 10 × 8 cm was closed using a non-cross-linked acellular dermal matrix (Egis® placed in two layers, beneath the rib plane and over it. A successful repair was achieved with no incisional herniation and with complete tissue regeneration, allowing natural respiratory movements. No complications were observed in the postoperative course. Biological non-cross-linked matrix, derived from porcine dermis, behaves like a scaffold supporting tissue regeneration; it can be successfully used as an alternative to synthetic mesh for chest wall reconstruction.

  6. A Case of “en bloc” Excision of a Chest Wall Leiomyosarcoma and Closure of the Defect with Non-Cross-Linked Collagen Matrix (Egis®)

    Science.gov (United States)

    Rastrelli, Marco; Tropea, Saveria; Spina, Romina; Costa, Alessandra; Stramare, Roberto; Mocellin, Simone; Bonavina, Maria Giuseppina; Rossi, Carlo Riccardo

    2016-01-01

    Sarcomas arising from the chest wall account for less than 20% of all soft tissue sarcomas, and at this site, primitive tumors are the most frequent to occur. Leiomyosarcoma is a malignant smooth muscle tumor and the best outcomes are achieved with wide surgical excision. Although advancements have been made in treatment protocols, leiomyosarcoma remains one of the more difficult soft tissue sarcoma to treat. Currently, general local control is obtained with surgical treatment with wide negative margins. We describe the case of a 50-year-old man who underwent a chest wall resection involving a wide portion of the pectoralis major and minor muscle, the serratus and part of the second, third and fourth ribs of the left side. The full-thickness chest wall defect of 10 × 8 cm was closed using a non-cross-linked acellular dermal matrix (Egis®) placed in two layers, beneath the rib plane and over it. A successful repair was achieved with no incisional herniation and with complete tissue regeneration, allowing natural respiratory movements. No complications were observed in the postoperative course. Biological non-cross-linked matrix, derived from porcine dermis, behaves like a scaffold supporting tissue regeneration; it can be successfully used as an alternative to synthetic mesh for chest wall reconstruction. PMID:27920698

  7. Embryonic chicken cornea and cartilage synthesize type IX collagen molecules with different amino-terminal domains.

    OpenAIRE

    Svoboda, K K; Nishimura, I; Sugrue, S P; Ninomiya, Y; Olsen, B R

    1988-01-01

    We have analyzed embryonic chicken cornea for the presence of type IX collagen mRNA and protein. Using RNA transfer blot analysis, we demonstrate that alpha 1(IX) and alpha 2(IX) mRNAs are expressed by corneal epithelial cells at the time that the primary stromal components are synthesized. The levels of the mRNAs decrease with increasing developmental age and are barely detectable at day 11 of development. In contrast, type IX collagen protein is detectable by immunofluorescence at days 5 an...

  8. Collagen metabolism in obesity

    DEFF Research Database (Denmark)

    Rasmussen, M H; Jensen, L T; Andersen, T

    1995-01-01

    OBJECTIVE: To investigate the impact of obesity, fat distribution and weight loss on collagen turnover using serum concentrations of the carboxyterminal propeptide of type I procollagen (S-PICP) and the aminoterminal propeptide of type III pro-collagen (S-PIIINP) as markers for collagen turnover...... (r = 0.37; P = 0.004), height (r = 0.27; P = 0.04), waist circumference (r = 0.35; P = 0.007), as well as with WHR (r = 0.33; P = 0.01) and was inversely correlated to age (r = -0.40; P = 0.002). Compared with randomly selected controls from a large pool of healthy volunteers, the obese patients had...... restriction (P obesity and associated with body fat distribution, suggesting...

  9. Visual outcome after corneal transplantation for corneal perforation and iris prolapse in 37 horses

    DEFF Research Database (Denmark)

    Henriksen, Michala de Linde; Plummer, C. E.; Mangan, B.

    2012-01-01

    We wanted to investigate the visual outcome of horses presented with iris prolapse and treated with corneal transplantation.......We wanted to investigate the visual outcome of horses presented with iris prolapse and treated with corneal transplantation....

  10. Collagen Homeostasis and Metabolism

    DEFF Research Database (Denmark)

    Magnusson, S Peter; Heinemeier, Katja M; Kjaer, Michael

    2016-01-01

    The musculoskeletal system and its collagen rich tissue is important for ensuring architecture of skeletal muscle, energy storage in tendon and ligaments, joint surface protection, and for ensuring the transfer of muscular forces into resulting limb movement. Structure of tendon is stable...... inactivity or immobilization of the human body will conversely result in a dramatic loss in tendon stiffness and collagen synthesis. This illustrates the importance of regular mechanical load in order to preserve the stabilizing role of the connective tissue for the overall function of the musculoskeletal...

  11. In vitro evaluation of the interactions between human corneal endothelial cells and extracellular matrix proteins

    International Nuclear Information System (INIS)

    Choi, Jin San; Kim, Eun Young; Kim, Min Jeong; Giegengack, Matthew; Khan, Faraaz A; Soker, Shay; Khang, Gilson

    2013-01-01

    The corneal endothelium is the innermost cell layer of the cornea and rests on Descemet's membrane consisting of various extracellular matrix (ECM) proteins which can directly affect the cellular behaviors such as cell adhesion, proliferation, polarity, morphogenesis and function. The objective of this study was to investigate the interactions between the ECM environment and human corneal endothelial cells (HCECs), with the ultimate goal to improve cell proliferation and function in vitro. To evaluate the interaction of HCECs with ECM proteins, cells were seeded on ECM-coated tissue culture dishes, including collagen type I (COL I), collagen type IV (COL IV), fibronectin (FN), FNC coating mix (FNC) and laminin (LM). Cell adhesion and proliferation of HCECs on each substratum and expression of CEC markers were studied. The results showed that HCECs plated on the COL I, COL IV, FN and FNC-coated plates had enhanced cell adhesion initially; the number for COL I, COL IV, FN and FNC was significantly higher than the control (P < 0.05). In addition, cells grown on ECM protein-coated dishes showed more compact cellular morphology and CEC marker expression compared to cells seeded on uncoated dishes. Collectively, our results suggest that an adequate ECM protein combination can provide a long-term culture environment for HCECs for corneal endothelium transplantation. (paper)

  12. Anterior corneal profile with variable asphericity.

    Science.gov (United States)

    Rosales, Marco A; Juárez-Aubry, Montserrat; López-Olazagasti, Estela; Ibarra, Jorge; Tepichín, Eduardo

    2009-12-10

    We present a corneal profile in which the eccentricity, e(Q=-e(2)), has a nonlinear continuous variation from the center outwards. This nonlinear variation is intended to fit and reproduce our current experimental data in which the anterior corneal surface of the human eye exhibits different values of e at different diameters. According to our clinical data, the variation is similar to an exponential decay. We propose a linear combination of two exponential functions to describe the variation of e. We then calculate the corneal sagittal height by substituting e in the first-order aspherical surface equation to obtain the corneal profile. This corneal profile will be used as a reference to analyze the resultant profiles of the customized corneal ablation in refractive surgery.

  13. Topical thrombin-related corneal calcification.

    Science.gov (United States)

    Kiratli, Hayyam; Irkeç, Murat; Alaçal, Sibel; Söylemezoğlu, Figen

    2006-09-01

    To report a highly unusual case of corneal calcification after brief intraoperative use of topical thrombin. A 44-year-old man underwent sclerouvectomy for ciliochoroidal leiomyoma, during which 35 UNIH/mL lyophilized bovine thrombin mixed with 9 mL of diluent containing 1500 mmol/mL calcium chloride was used. From the first postoperative day, corneal and anterior lenticular capsule calcifications developed, and corneal involvement slightly enlarged thereafter. A year later, 2 corneal punch biopsies confirmed calcification mainly in the Bowman layer. Topical treatment with 1.5% ethylenediaminetetraacetic acid significantly restored corneal clarity. Six months later, a standard extracapsular cataract extraction with intraocular lens placement improved visual acuity to 20/60. This case suggests that topical thrombin drops with elevated calcium concentrations may cause acute corneal calcification in Bowman layer and on the anterior lens capsule.

  14. Evaluation of corneal symmetry after UV corneal crosslinking for keratoconus

    Directory of Open Access Journals (Sweden)

    Mofty H

    2017-11-01

    Full Text Available Hanan Mofty,1,2 Khaled Alzahrani,2 Fiona Carley,3 Sophie Harper,3 Arun Brahma,3 Leon Au,3 Debbie Morley,3 M Chantal Hillarby2 1Optometry Department, College of Applied Medical Science, King Saud University, Riyadh, Kingdom of Saudi Arabia; 2Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, 3Manchester Royal Eye Hospital, Manchester, UK Purpose: The purpose of this study was to assess UV corneal crosslinking (CXL treatment outcomes for keratoconus by evaluating the corneal regularity in patients through follow-up using the Oculus Pentacam.Patients and methods: A total of 18 eyes from CXL patients with keratoconus were studied before and after CXL treatment, and six eyes from six patients who were not treated with CXL served as controls. Treated patients had Pentacam images taken before CXL treatment and regularly 3 months post treatment up to the 12th month. Controls were imaged during their first appointment and after 12 months. Symmetry and asphericity were evaluated and correlated with both best-corrected visual acuity (BCVA and maximum K-readings.Results: In the CXL-treated group, there was a significant improvement in the index of symmetrical variation (ISV and keratoconus index (KI at 3 months and in the index of height asymmetry (IHA and minimum radius of curvature (Rmin at 9 months post treatment. On the contrary, the untreated group’s indices showed some significant worsening in ISV, KI, central keratoconus index (CKI, and Rmin. A novel finding in our study was a slight positive shift of anterior asphericity in the 6 mm, 7 mm, and 8 mm 3 months after treatment, which had a correlation with BCVA (R2=0.390, p=0.053 and a strong correlation with maximum K-reading (R2=0.690, p=0.005. However, the untreated group had no significant changes after 1 year.Conclusion: The corneal asymmetrical shape is associated with the spherical aberration alteration

  15. The effect of vitamin C deficiency and chronic ultraviolet-B exposure on corneal ultrastructure: a preliminary investigation

    Science.gov (United States)

    Hayes, Sally; Cafaro, Thamara A.; Boguslawska, Patrycja J.; Kamma-Lorger, Christina S.; Boote, Craig; Harris, Jonathan; Young, Robert; Hiller, Jennifer; Terrill, Nicholas; Meek, Keith M.

    2011-01-01

    Purpose In the visually debilitating condition of climatic droplet keratopathy, corneal transparency is progressively lost. Although the precise cause of the disease and the mechanism by which it progresses are not known, a lifetime exposure to high solar radiation and a vitamin C–deficient diet may be involved in its development. This study examines the effect of dietary ascorbate levels and ultraviolet (UV)-B exposure on corneal stromal structure. Methods Eight guinea pigs were divided into four treatment groups (A, B, C, and D). For 15 weeks, Groups A and C were fed an ascorbate-rich diet (2 mg/100 g bodyweight/day), while Groups B and D received an ascorbate-deficient diet (0.07 mg/100 g bodyweight/day). For the last 12 weeks of the study, Groups C and D also experienced chronic UVB exposure (0.12 J/cm2 for 40 min/day). Following euthanasia, the corneas were enucleated and their stromal ultrastructure examined using X-ray scattering and electron microscopy. Results UVB exposure resulted in an increased corneal thickness (p<0.001), but this was not accompanied by a widespread expansion of the collagen fibrillar array, and in the case of ascorbate-deficient animals, stromal thickening was associated with the compaction of collagen fibrils (p<0.01). Neither UVB exposure nor ascorbic acid deficiency caused any change in the average diameter or D-periodicity of the stromal collagen fibrils. Conclusions UVB-induced changes in the corneal ultrastructure were most pronounced in animals fed an ascorbic acid–deficient diet. This suggests that ascorbic acid may play a vital role in protecting the corneal stroma from the harmful effects of UVB. PMID:22171156

  16. [The genetics of collagen diseases].

    Science.gov (United States)

    Kaplan, J; Maroteaux, P; Frezal, J

    1986-01-01

    Heritable disorders of collagen include Ehler-Danlos syndromes (11 types are actually known), Larsen syndrome and osteogenesis imperfecta. Their clinical, genetic and biochemical features are reviewed. Marfan syndrome is closely related to heritable disorders of collagen.

  17. Manipulation of in vitro collagen matrix architecture for scaffolds of improved physiological relevance

    Science.gov (United States)

    Hapach, Lauren A.; VanderBurgh, Jacob A.; Miller, Joseph P.; Reinhart-King, Cynthia A.

    2015-12-01

    Type I collagen is a versatile biomaterial that is widely used in medical applications due to its weak antigenicity, robust biocompatibility, and its ability to be modified for a wide array of applications. As such, collagen has become a major component of many tissue engineering scaffolds, drug delivery platforms, and substrates for in vitro cell culture. In these applications, collagen constructs are fabricated to recapitulate a diverse set of conditions. Collagen fibrils can be aligned during or post-fabrication, cross-linked via numerous techniques, polymerized to create various fibril sizes and densities, and copolymerized into a wide array of composite scaffolds. Here, we review approaches that have been used to tune collagen to better recapitulate physiological environments for use in tissue engineering applications and studies of basic cell behavior. We discuss techniques to control fibril alignment, methods for cross-linking collagen constructs to modulate stiffness, and composite collagen constructs to better mimic physiological extracellular matrix.

  18. Mechanisms of lamellar collagen formation in connective tissues.

    Science.gov (United States)

    Ghazanfari, Samaneh; Khademhosseini, Ali; Smit, Theodoor H

    2016-08-01

    The objective of tissue engineering is to regenerate functional tissues. Engineering functional tissues requires an understanding of the mechanisms that guide the formation and evolution of structure in the extracellular matrix (ECM). In particular, the three-dimensional (3D) collagen fiber arrangement is important as it is the key structural determinant that provides mechanical integrity and biological function. In this review, we survey the current knowledge on collagen organization mechanisms that can be applied to create well-structured functional lamellar tissues and in particular intervertebral disc and cornea. Thus far, the mechanisms behind the formation of cross-aligned collagen fibers in the lamellar structures is not fully understood. We start with cell-induced collagen alignment and strain-stabilization behavior mechanisms which can explain a single anisotropically aligned collagen fiber layer. These mechanisms may explain why there is anisotropy in a single layer in the first place. However, they cannot explain why a consecutive collagen layer is laid down with an alternating alignment. Therefore, we explored another mechanism, called liquid crystal phasing. While dense concentrations of collagen show such behavior, there is little evidence that the conditions for liquid crystal phasing are actually met in vivo. Instead, lysyl aldehyde-derived collagen cross-links have been found essential for correct lamellar matrix deposition. Furthermore, we suggest that supra-cellular (tissue-level) shear stress may be instrumental in the alignment of collagen fibers. Understanding the potential mechanisms behind the lamellar collagen structure in connective tissues will lead to further improvement of the regeneration strategies of functional complex lamellar tissues. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Corneal iron ring after conductive keratoplasty.

    Science.gov (United States)

    Kymionis, George D; Naoumidi, Tatiana L; Aslanides, Ioannis M; Pallikaris, Ioannis G

    2003-08-01

    To report formation of corneal iron ring deposits after conductive keratoplasty. Observational case report. Case report. A 54-year-old woman underwent conductive keratoplasty for hyperopia. One year after conductive keratoplasty, iron ring pattern pigmentation was detected at the corneal epithelium of both eyes. This is the first report of the appearance of corneal iron ring deposits following conductive keratoplasty treatment in a patient. It is suggested that alterations in tear film stability, resulting from conductive keratoplasty-induced changes in corneal curvature, constitute the contributory factor for these deposits.

  20. Tear Mediators in Corneal Ectatic Disorders.

    Directory of Open Access Journals (Sweden)

    Dorottya Pásztor

    Full Text Available To compare the concentrations of 11 tear mediators in order to reveal the biochemical difference between pellucid marginal degeneration (PMD and keratoconus (KC.We have designed a cross-sectional study in which patients with corneal ectasia based on slit-lamp biomicroscopy and Pentacam HR (keratometry values (K1, K2, Kmax, astigmatism, minimal radius of curvature (Rmin, corneal thickness (Apex and Min, indices (surface variation, vertical asymmetry, keratoconus, central keratoconus, height asymmetry and decentration were enrolled. Eyes of keratoconic patients were similar to the PMD patients in age and severity (K2, Kmax and Rmin. Non-stimulated tear samples were collected from nine eyes of seven PMD patients, 55 eyes of 55 KC patients and 24 eyes of 24 healthy controls. The mediators' (interleukin -6, -10, chemokine ligand 5, -8, -10, matrix metalloproteinase (MMP -9, -13, tissue inhibitor of metalloproteinases (TIMP-1, tissue plasminogen activator, plasminogen activator inhibitor, nerve growth factor concentrations were measured using Cytometric Bead Array.MMP-9 was the only mediator which presented relevant variances between the two patient groups (p = 0.005. The ratios of MMP-9 and TIMP-1 were 2.45, 0.40 and 0.23 in PMD, KC and the controls, respectively.As far as we are aware, this is the first study that aims to reveal the biochemical differences between PMD and KC. Further studies of biomarkers to investigate the precise role of these mediators need to be defined, and it is important to confirm the observed changes in a larger study to gain further insights into the molecular alterations in PMD.

  1. Comparative Confocal and Histopathological Study of Corneal Changes in Multiple Myeloma.

    Science.gov (United States)

    Micali, Antonio; Roszkowska, Anna M; Postorino, Elisa I; Rania, Laura; Aragona, Emanuela; Wylegala, Edward; Nowinska, Anna; Ieni, Antonio; Calimeri, Sebastiano; Pisani, Antonina; Aragona, Pasquale; Puzzolo, Domenico

    2017-01-01

    Corneal opacities rarely occur in multiple myeloma (MM). Our study correlates the findings of in vivo confocal microscopy (IVCM), a useful diagnostic tool, with histopathological features of corneal opacities appearing in a patient with MM. Case report. A 53-year-old man developed corneal opacities in both eyes, more pronounced in the left eye. After IVCM examination, he underwent penetrating keratoplasty in the left eye, and the button was processed for light and electron microscopy and immunohistochemistry. The diagnosis of MM was made, as confirmed by the elevation of IgGk light chains. IVCM demonstrated hyperreflective areas at the epithelial level, hyperreflective keratocytes of dendritic and lamellar morphology in whole stroma, and hyperreflective endothelial cells. Histopathological examination disclosed many vacuoles in the epithelial cell cytoplasm and a homogenous granular material in the Bowman layer. In stroma, keratocytes of different shape and size, with vesicles laden with an abnormal material, were evident. In Descemet membrane, the posterior nonbanded zone had a honeycomb appearance because of the presence of many roundish spaces among wide-spaced collagen fibers. Endothelial cells demonstrated vesicles filled with a material of uneven electron density. Immunohistochemical analysis showed strong positivity for IgGk light chains in keratocytes and among stromal lamellae. This is the first study describing a correspondence between IVCM features and histopathological alterations observed in corneal opacities in MM. The results of this study improve the current understanding of the pictures obtained by IVCM studies.

  2. Control of Scar Tissue Formation in the Cornea: Strategies in Clinical and Corneal Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Samantha L. Wilson

    2012-09-01

    Full Text Available Corneal structure is highly organized and unified in architecture with structural and functional integration which mediates transparency and vision. Disease and injury are the second most common cause of blindness affecting over 10 million people worldwide. Ninety percent of blindness is permanent due to scarring and vascularization. Scarring caused via fibrotic cellular responses, heals the tissue, but fails to restore transparency. Controlling keratocyte activation and differentiation are key for the inhibition and prevention of fibrosis. Ophthalmic surgery techniques are continually developing to preserve and restore vision but corneal regression and scarring are often detrimental side effects and long term continuous follow up studies are lacking or discouraging. Appropriate corneal models may lead to a reduced need for corneal transplantation as presently there are insufficient numbers or suitable tissue to meet demand. Synthetic optical materials are under development for keratoprothesis although clinical use is limited due to implantation complications and high rejection rates. Tissue engineered corneas offer an alternative which more closely mimic the morphological, physiological and biomechanical properties of native corneas. However, replication of the native collagen fiber organization and retaining the phenotype of stromal cells which prevent scar-like tissue formation remains a challenge. Careful manipulation of culture environments are under investigation to determine a suitable environment that simulates native ECM organization and stimulates keratocyte migration and generation.

  3. Rheology of Heterotypic Collagen Networks

    NARCIS (Netherlands)

    Piechocka, I.K.; van Oosten, A.S.G.; Breuls, R.G.M.; Koenderink, G.H.

    2011-01-01

    Collagen fibrils are the main structural element of connective tissues. In many tissues, these fibrils contain two fibrillar collagens (types I and V) in a ratio that changes during tissue development, regeneration, and various diseases. Here we investigate the influence of collagen composition on

  4. From Nano to Macro: Studying the Hierarchical Structure of the Corneal Extracellular Matrix

    Science.gov (United States)

    Quantock, Andrew J.; Winkler, Moritz; Parfitt, Geraint J.; Young, Robert D.; Brown, Donald J.; Boote, Craig; Jester, James V.

    2014-01-01

    In this review, we discuss current methods for studying ocular extracellular matrix (ECM) assembly from the ‘nano’ to the ‘macro’ levels of hierarchical organization. Since collagen is the major structural protein in the eye, providing mechanical strength and controlling ocular shape, the methods presented focus on understanding the molecular assembly of collagen at the nanometer level using x-ray scattering through to the millimeter to centimeter level using nonlinear optical (NLO) imaging of second harmonic generated (SHG) signals. Three-dimensional analysis of ECM structure is also discussed, including electron tomography, serial block face scanning electron microscopy (SBF-SEM) and digital image reconstruction. Techniques to detect non-collagenous structural components of the ECM are also presented, and these include immunoelectron microscopy and staining with cationic dyes. Together, these various approaches are providing new insights into the structural blueprint of the ocular ECM, and in particular that of the cornea, which impacts upon our current understanding of the control of corneal shape, pathogenic mechanisms underlying ectatic disorders of the cornea and the potential for corneal tissue engineering. PMID:25819457

  5. Collagen derived serum markers in carcinoma of the prostate

    DEFF Research Database (Denmark)

    Rudnicki, M; Jensen, L T; Iversen, P

    1995-01-01

    Three new collagen markers deriving from the collagenous matrix, e.g. carboxyterminal propeptide of type I procollagen (PICP), carboxy-terminal pyridinoline cross-linked telopeptide of type I collagen (ICTP), and aminoterminal propeptide of type III procollagen (PIIINP) were used for the diagnose...... of prostatic bone metastases. Blood samples were obtained prior to biopsy or TURP. Serum PICP, PIIINP and ICTP were measured with commercial available RIAs and PSA by IRMA. Serum PSA was increased in patients with local prostatic cancer compared with patients with hyperplasia (p

  6. Uniform spatial distribution of collagen fibril radii within tendon implies local activation of pC-collagen at individual fibrils

    Science.gov (United States)

    Rutenberg, Andrew D.; Brown, Aidan I.; Kreplak, Laurent

    2016-08-01

    Collagen fibril cross-sectional radii show no systematic variation between the interior and the periphery of fibril bundles, indicating an effectively constant rate of collagen incorporation into fibrils throughout the bundle. Such spatially homogeneous incorporation constrains the extracellular diffusion of collagen precursors from sources at the bundle boundary to sinks at the growing fibrils. With a coarse-grained diffusion equation we determine stringent bounds, using parameters extracted from published experimental measurements of tendon development. From the lack of new fibril formation after birth, we further require that the concentration of diffusing precursors stays below the critical concentration for fibril nucleation. We find that the combination of the diffusive bound, which requires larger concentrations to ensure homogeneous fibril radii, and lack of nucleation, which requires lower concentrations, is only marginally consistent with fully processed collagen using conservative bounds. More realistic bounds may leave no consistent concentrations. Therefore, we propose that unprocessed pC-collagen diffuses from the bundle periphery followed by local C-proteinase activity and subsequent collagen incorporation at each fibril. We suggest that C-proteinase is localized within bundles, at fibril surfaces, during radial fibrillar growth. The much greater critical concentration of pC-collagen, as compared to fully processed collagen, then provides broad consistency between homogeneous fibril radii and the lack of fibril nucleation during fibril growth.

  7. Proteomics of Fuchs' Endothelial Corneal Dystrophy support that the extracellular matrix of Descemet's membrane is disordered

    DEFF Research Database (Denmark)

    Poulsen, Ebbe Toftgaard; Dyrlund, Thomas F; Runager, Kasper

    2014-01-01

    Fuchs' endothelial corneal dystrophy (FECD) is a major corneal disorder affecting the innermost part of the cornea, leading to visual impairment. As the morphological changes in FECD are mainly observed in the extracellular matrix of the Descemet's membrane/endothelial layer we determined...... that the morphological changes observed in FECD is caused in part by an aberrant assembly of the extracellular matrix within the Descemet's membrane/endothelial layer......., respectively, of which 10 were significantly regulated. The results indicated that the level of type VIII collagen was unaltered even though the protein previously has been implicated in familial early onset forms of the disease. Using the second relative quantitation method iTRAQ we identified 22...

  8. Hyperplastic corneal pannus: an immunohistochemical analysis and review.

    Science.gov (United States)

    Jakobiec, Frederick A; Stacy, Rebecca C; Mendoza, Pia R; Chodosh, James

    2014-01-01

    An exuberant corneal pannus usually develops in adults with a history of surgery or trauma in the anterior central stroma and appears as a glistening, vascularized, moderately elevated, well circumscribed white nodule. We describe a 78-year-old woman with such a pannus, which in the past has typically been referred to as keloidal or hypertrophic. The involved eye had only light perception, and she underwent a penetrating keratoplasty that improved her vision to 20/100. Histopathologic and immunohistochemical evaluations of a the specimen disclosed a reactive spindle cell stromal proliferation of myofibroblasts that were smooth muscle actin positive with a low Ki67 proliferation index. Desmin, caldesmon, and calponin were negative, in keeping with the incomplete myofilamentary differentiation of a myofibroblast. There was a generous admixture of CD68/163-positive histiocytes and dispersed C3/5-positive T-lymphocytes. An absence of CD138- and IgG4-positive plasma cells ruled out an IgG4-related disease. For a lesion to be keloidal, the collagen must have a thick hyaline character, sharp edges, and a sparsity of intervening cells and vessels. A hypertrophic pannus would be composed of large swollen cells not necessarily increased in number. We therefore recommend adoption of the term hyperplastic for lesions like that described here because of the obvious increase in cellularity from proliferating myofibroblasts and the lack of true keloidal collagen. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Rechazo y retrasplante corneal Corneal rejection and re-transplantation

    Directory of Open Access Journals (Sweden)

    Miguel O Mokey Castellanos

    2007-06-01

    Full Text Available Se efectuó una investigación observacional análítica retrospectiva, sobre los transplantes corneales efectuados en el Servicio de Oftalmología del Hospital "Hermanos Ameijeiras. Rechazaron 76 pacientes, que se compararon con un control de 89 pacientes, que en un período similar no tuvieron rechazo. El queratocono fue la afección corneal que predominó. El primer lugar en los rechazos correspondió a queratoherpes (43,5 %. El menor índice de rechazo fue para el queratocono (8,8 %. Se analizó la multiplicidad de rechazos; y fue frecuente que se presentara un solo rechazo, aunque sí hubo congruencia entre el número de rechazos y la necesidad de retrasplantes. Se encontró que los resultados de la conducta médica o quirúrgica se relacionaban con la causa. Se calcula un índice de supervivencia (Kaplan-Meier, que concluye que en los primeros dos años existe menos posibilidad de aparición de rechazoAn retrospective observational analytical research was conducted on corneal transplants performed at Ophthalmological Service in “Hermanos Ameijeiras” hospital . Seventy six patients had graft rejection and were compared to a control group of 89 patients that did not present rejection in the same period of time. Keratoconus was the prevailing corneal problem. The highest rejection rate corresponded to keratoherpes (43,5% whereas the lowest rate was for keratoconus (8,8%. Multiplicity of rejections was analyzed and it was found that mostly one graft rejection occured, but number of rejections was associated with the need of re-transplantation. It was found that the results of medical or surgical performance were related to the cause of graft rejection. A survival index (Kaplan-Meier was estimated, which showed that occurence of graf rejection is less probable in the first two years

  10. Chemical Stabilisation of Collagen as a Biomimetic

    Directory of Open Access Journals (Sweden)

    R. Gordon Paul

    2003-01-01

    Full Text Available Collagen is the most abundant protein in animals and because of its high mechanical strength and good resistance to degradation has been utilized in a wide range of products in industry whilst its low antigenicity has resulted in its widespread use in medicine. Collagen products can be purified from fibres, molecules reconstituted as fibres or from specific recombinant polypeptides with preferred properties. A common feature of all these biomaterials is the need for stable chemical cross-linking to control the mechanical properties and the residence time in the body, and to some extent the immunogenicity of the device. This can be achieved by a number of different cross-linking agents that react with specific amino acid residues on the collagen molecule imparting individual biochemical, thermal and mechanical characteristics to the biomaterial. In this review we have summarised the major techniques for testing these characteristics and the mechanisms involved in the variety of cross-linking reactions to achieve particular properties..

  11. Chitosan and thiolated chitosan: Novel therapeutic approach for preventing corneal haze after chemical injuries.

    Science.gov (United States)

    Zahir-Jouzdani, Forouhe; Mahbod, Mirgholamreza; Soleimani, Masoud; Vakhshiteh, Faezeh; Arefian, Ehsan; Shahosseini, Saeed; Dinarvand, Rasoul; Atyabi, Fatemeh

    2018-01-01

    Corneal haze, commonly caused by deep physical and chemical injuries, can greatly impair vision. Growth factors facilitate fibroblast proliferation and differentiation, which leads to haze intensity. In this study, the potential effect of chitosan (CS) and thiolated-chitosan (TCS) nanoparticles and solutions on inhibition of fibroblast proliferation, fibroblast to myofibroblast differentiation, neovascularization, extracellular matrix (ECM) deposition, and pro-fibrotic cytokine expression was examined. Transforming growth factor beta-1 (TGFβ 1 ) was induced by interleukin-6 (IL6) in human corneal fibroblasts and expression levels of TGFβ 1 , Platelet-derived growth factor (PDGF), α-smooth muscle actins (α-SMA), collagen type I (Col I), fibronectin (Fn) and vascular endothelial growth factor (VEGF) were quantified using qRT-PCR. To assess wound-healing capacity, TCS-treated mice were examined for α-SMA positive cells, collagen deposition, inflammatory cells and neovascularization through pathological immunohistochemistry. The results revealed that CS and TCS could down-regulate the expression levels of TGFβ 1 and PDGF comparable to that of TGFβ 1 knockdown experiment. However, down-regulation of TGFβ 1 was not regulated through miR29b induction. Neovascularization along with α-SMA and ECM deposition were significantly diminished. According to these findings, CS and TCS can be considered as potential anti-fibrotic and anti-angiogenic therapeutics. Furthermore, TCS, thiolated derivative of CS, will increase mucoadhesion of the polymer at the corneal surface which makes the polymer efficient and non-toxic therapeutic approach for corneal injuries. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Mimicking corneal stroma using keratocyte-loaded photopolymerizable methacrylated gelatin hydrogels.

    Science.gov (United States)

    Kilic Bektas, Cemile; Hasirci, Vasif

    2018-04-01

    Cell-laden methacrylated gelatin (GelMA) hydrogels with high (approximately 90%) transparency were prepared to mimic the natural form and function of corneal stroma. They were synthesized from GelMA with a methacrylation degree of 70% as determined by nuclear magnetic resonance. Hydrogels were strong enough to withstand handling. Stability studies showed that 87% of the GelMA hydrogels remained after 21 days in phosphate buffered saline (PBS). Cell viability in the first 2 days was over 90% for the human keratocytes loaded in the gels as determined with the live-dead analysis. Cells in the hydrogel elongated and connected to each other as observed by confocal laser scanning microscopy (CLSM) images and scanning electron microscope analysis after 3 weeks in the culture medium and cells were seen to be distributed throughout the hydrogel bulk. Cells were found to synthesize collagen Types I and V, decorin, and biglycan (representative collagens and proteoglycans of human corneal stroma, respectively) showing that keratocytes maintained their functions and preserved their phenotypes in the hydrogels. Transparency of cell-loaded and cell-free hydrogels after 21 days was found to be over 90% at all time points in the visible light range and was comparable to the transparency of the native cornea. The corneal stroma equivalent produced in this study that has cells entrapped in it leads to a product with homogenous distribution of cells. It was transparent at the very beginning and is expected to allow better vision than nontransparent substrates. It, therefore, has a significant potential to be used as an alternative to the current products used to treat corneal blindness. Copyright © 2017 John Wiley & Sons, Ltd.

  13. Corynebacterium macginleyi isolated from a corneal ulcer

    Directory of Open Access Journals (Sweden)

    Kathryn Ruoff

    2010-02-01

    Full Text Available We report the isolation of Corynebacterium macginleyi from the corneal ulcer culture of a patient, later enrolled in the Steroids for Corneal Ulcer Trial (SCUT. To our knowledge this is the first published report from North America of the recovery of C. macginleyi from a serious ocular infection.

  14. Do topical antibiotics help corneal epithelial trauma?

    OpenAIRE

    King, J. W.; Brison, R. J.

    1993-01-01

    Topical antibiotics are routinely used in emergency rooms to treat corneal trauma, although no published evidence supports this treatment. In a noncomparative clinical trial, 351 patients with corneal epithelial injuries were treated without antibiotics. The infection rate was 0.7%, suggesting that such injuries can be safely and effectively managed without antibiotics. A comparative clinical trial is neither warranted nor feasible.

  15. Corneal laceration caused by river crab

    Directory of Open Access Journals (Sweden)

    Vinuthinee N

    2015-01-01

    Full Text Available Naidu Vinuthinee,1,2 Anuar Azreen-Redzal,1 Jaafar Juanarita,1 Embong Zunaina2 1Department of Ophthalmology, Hospital Sultanah Bahiyah, Alor Setar, 2Department of Ophthalmology, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Malaysia Abstract: A 5-year-old boy presented with right eye pain associated with tearing and photophobia of 1-day duration. He gave a history of playing with a river crab when suddenly the crab clamped his fingers. He attempted to fling the crab off, but the crab flew and hit his right eye. Ocular examination revealed a right eye corneal ulcer with clumps of fibrin located beneath the corneal ulcer and 1.6 mm level of hypopyon. At presentation, the Seidel test was negative, with a deep anterior chamber. Culture from the corneal scrapping specimen grew Citrobacter diversus and Proteus vulgaris, and the boy was treated with topical gentamicin and ceftazidime eyedrops. Fibrin clumps beneath the corneal ulcer subsequently dislodged, and revealed a full-thickness corneal laceration wound with a positive Seidel test and shallow anterior chamber. The patient underwent emergency corneal toileting and suturing. Postoperatively, he was treated with oral ciprofloxacin 250 mg 12-hourly for 1 week, topical gentamicin, ceftazidime, and dexamethasone eyedrops for 4 weeks. Right eye vision improved to 6/9 and 6/6 with pinhole at the 2-week follow-up following corneal suture removal. Keywords: corneal ulcer, pediatric trauma, ocular injury

  16. Glutaraldehyde cross-linking of amniotic membranes affects their nanofibrous structures and limbal epithelial cell culture characteristics

    Directory of Open Access Journals (Sweden)

    Lai JY

    2013-10-01

    Full Text Available Jui-Yang Lai,1–3 David Hui-Kang Ma4,5 1Institute of Biochemical and Biomedical Engineering, 2Biomedical Engineering Research Center, 3Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan; 4Limbal Stem Cell Laboratory, Department of Ophthalmology, Chang Gung Memorial Hospital, Taoyuan, Taiwan; 5Department of Chinese Medicine, Chang Gung University, Taoyuan, Taiwan Abstract: Given that the cells can sense nanometer dimensions, the chemical cross-linking-mediated alteration in fibrillar structure of collagenous tissue scaffolds is critical to determining their cell culture performances. This article explores, for the first time, the effect of nanofibrous structure of glutaraldehyde (GTA cross-linked amniotic membrane (AM on limbal epithelial cell (LEC cultivation. Results of ninhydrin assays demonstrated that the amount of new cross-links formed between the collagen chains is significantly increased with increasing the cross-linking time from 1 to 24 hours. By transmission electron microscopy, the AM treated with GTA for a longer duration exhibited a greater extent of molecular aggregation, thereby leading to a considerable increase in nanofiber diameter and resistance against collagenase degradation. In vitro biocompatibility studies showed that the samples cross-linked with GTA for 24 hours are not well-tolerated by the human corneal epithelial cell cultures. When the treatment duration is less than 6 hours, the biological tissues cross-linked with GTA for a longer time may cause slight reductions in 3-(4,5-dimethylthiazol-2-yl-5-(3-carboxymethoxyphenyl-2-(4-sulfophenyl-2H-tetrazolium, inner salt, and anti-inflammatory activities. Nevertheless, significant collagen molecular aggregation also enhances the stemness gene expression, indicating a high ability of these AM matrices to preserve the progenitors of LECs in vitro. It is concluded that GTA cross-linking of collagenous tissue materials may affect their nanofibrous

  17. The tissue-engineered human cornea as a model to study expression of matrix metalloproteinases during corneal wound healing.

    Science.gov (United States)

    Couture, Camille; Zaniolo, Karine; Carrier, Patrick; Lake, Jennifer; Patenaude, Julien; Germain, Lucie; Guérin, Sylvain L

    2016-02-01

    Corneal injuries remain a major cause of consultation in the ophthalmology clinics worldwide. Repair of corneal wounds is a complex mechanism that involves cell death, migration, proliferation, differentiation, and extracellular matrix (ECM) remodeling. In the present study, we used a tissue-engineered, two-layers (epithelium and stroma) human cornea as a biomaterial to study both the cellular and molecular mechanisms of wound healing. Gene profiling on microarrays revealed important alterations in the pattern of genes expressed by tissue-engineered corneas in response to wound healing. Expression of many MMPs-encoding genes was shown by microarray and qPCR analyses to increase in the migrating epithelium of wounded corneas. Many of these enzymes were converted into their enzymatically active form as wound closure proceeded. In addition, expression of MMPs by human corneal epithelial cells (HCECs) was affected both by the stromal fibroblasts and the collagen-enriched ECM they produce. Most of all, results from mass spectrometry analyses provided evidence that a fully stratified epithelium is required for proper synthesis and organization of the ECM on which the epithelial cells adhere. In conclusion, and because of the many characteristics it shares with the native cornea, this human two layers corneal substitute may prove particularly useful to decipher the mechanistic details of corneal wound healing. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Designing Hydrogel Adhesives for Corneal Wound Repair

    Science.gov (United States)

    Grinstaff, Mark W.

    2013-01-01

    Today, corneal wounds are repaired using nylon sutures. Yet there are a number of complications associated with suturing the cornea, and thus there is interest in an adhesive to replace or supplement sutures in the repair of corneal wounds. We are designing and evaluating corneal adhesives prepared from dendrimers – single molecular weight, highly branched polymers. We have explored two strategies to form these ocular adhesives. The first involves a photocrosslinking reaction and the second uses a peptide ligation reactions to couple the individual dendrimers together to from the adhesive. These adhesives were successfully used to repair corneal perforations, close the flap produced in a LASIK procedure, and secure a corneal transplant. PMID:17889330

  19. Healed corneal ulcer with keloid formation.

    Science.gov (United States)

    Alkatan, Hind M; Al-Arfaj, Khalid M; Hantera, Mohammed; Al-Kharashi, Soliman

    2012-04-01

    We are reporting a 34-year-old Arabic white female patient who presented with a white mass covering her left cornea following multiple ocular surgeries and healed corneal ulcer. The lesion obscured further view of the iris, pupil and lens. The patient underwent penetrating keratoplasty and the histopathologic study of the left corneal button showed epithelial hyperplasia, absent Bowman's layer and subepithelial fibrovascular proliferation. The histopathologic appearance was suggestive of a corneal keloid which was supported by further ultrastructural study. The corneal graft remained clear 6 months after surgery and the patient was satisfied with the visual outcome. Penetrating keratoplasty may be an effective surgical option for corneal keloids in young adult patients.

  20. Late onset corneal ectasia after LASIK surgery.

    Science.gov (United States)

    Said, Ashraf; Hamade, Issam H; Tabbara, Khalid F

    2011-07-01

    To report late onset corneal ectasia following myopic LASIK. A retrospective cohort case series. Nineteen patients with late onset corneal ectasia following LASIK procedure were examined at The Eye Center, Riyadh, Saudi Arabia. Patients underwent LASIK for myopia with spherical equivalent ranging from -1.4 to -13.75 diopters. Age and gender, history of systemic or local diseases, and time of onset of corneal ectasia were recorded. Eye examination and corneal topographical analyses were done before and after LASIK surgery. Nineteen patients (29 eyes) with late onset corneal ectasia were identified from 1998 to 2008 in 13 male and six female patients. The mean follow-up period was 108 ± 23 months (range 72-144 months). No patient had pre-operative identifiable risk factors for corneal ectasia and the mean time of onset was 57 ± 24 months (range 24-120 months after LASIK). The pre-operative values included mean central pachymetry 553 ± 25 μm, mean keratometry reading of 42.9 ± 1.5 diopters, average oblique cylinder of 1.4 ± 1.2 diopters, posterior surface elevation of 26 ± 2.1 diopters, corneal flap thickness of 160 μm, mean spherical equivalent of -5.6 ± 3.6 diopters, and calculated residual corneal stromal bed thickness was 288 ± 35 μm. Three (5 eyes) patients developed ectasia after pregnancy. Three (4 eyes) patients developed corneal ectasia following severe adenoviral keratoconjunctivitis and had positive PCR for adenovirus type 8. Corneal ectasia may develop many years after LASIK surgery and symptoms could go undetected for some time. Pregnancy and adenoviral keratoconjunctivitis occurred post-operatively in six patients.

  1. Corneal modeling for analysis of photorefractive keratectomy

    Science.gov (United States)

    Della Vecchia, Michael A.; Lamkin-Kennard, Kathleen

    1997-05-01

    Procedurally, excimer photorefractive keratectomy is based on the refractive correction of composite spherical and cylindrical ophthalmic errors of the entire eye. These refractive errors are inputted for correction at the corneal plane and for the properly controlled duration and location of laser energy. Topography is usually taken to correspondingly monitor spherical and cylindrical corneorefractive errors. While a corneal topographer provides surface morphologic information, the keratorefractive photoablation is based on the patient's spherical and cylindrical spectacle correction. Topography is at present not directly part of the procedural deterministic parameters. Examination of how corneal curvature at each of the keratometric reference loci affect the shape of the resultant corneal photoablated surface may enhance the accuracy of the desired correction. The objective of this study was to develop a methodology to utilize corneal topography for construction of models depicting pre- and post-operative keratomorphology for analysis of photorefractive keratectomy. Multiple types of models were developed then recreated in optical design software for examination of focal lengths and other optical characteristics. The corneal models were developed using data extracted from the TMS I corneal modeling system (Computed Anatomy, New York, NY). The TMS I does not allow for manipulation of data or differentiation of pre- and post-operative surfaces within its platform, thus models needed to be created for analysis. The data were imported into Matlab where 3D models, surface meshes, and contour plots were created. The data used to generate the models were pre- and post-operative curvatures, heights from the corneal apes, and x-y positions at 6400 locations on the corneal surface. Outlying non-contributory points were eliminated through statistical operations. Pre- and post- operative models were analyzed to obtain the resultant changes in the corneal surfaces during PRK

  2. Collagen-Gold Nanoparticle Conjugates for Versatile Biosensing

    Directory of Open Access Journals (Sweden)

    Sarah Unser

    2017-02-01

    Full Text Available Integration of noble metal nanoparticles with proteins offers promising potential to create a wide variety of biosensors that possess both improved selectivity and versatility. The multitude of functionalities that proteins offer coupled with the unique optical properties of noble metal nanoparticles can allow for the realization of simple, colorimetric sensors for a significantly larger range of targets. Herein, we integrate the structural protein collagen with 10 nm gold nanoparticles to develop a protein-nanoparticle conjugate which possess the functionality of the protein with the desired colorimetric properties of the nanoparticles. Applying the many interactions that collagen undergoes in the extracellular matrix, we are able to selectively detect both glucose and heparin with the same collagen-nanoparticle conjugate. Glucose is directly detected through the cross-linking of the collagen fibrils, which brings the attached nanoparticles into closer proximity, leading to a red-shift in the LSPR frequency. Conversely, heparin is detected through a competition assay in which heparin-gold nanoparticles are added to solution and compete with heparin in the solution for the binding sites on the collagen fibrils. The collagen-nanoparticle conjugates are shown to detect both glucose and heparin in the physiological range. Lastly, glucose is selectively detected in 50% mouse serum with the collagen-nanoparticle devices possessing a linear range of 3–25 mM, which is also within the physiologically relevant range.

  3. Collagen macromolecular drug delivery systems

    International Nuclear Information System (INIS)

    Gilbert, D.L.

    1988-01-01

    The objective of this study was to examine collagen for use as a macromolecular drug delivery system by determining the mechanism of release through a matrix. Collagen membranes varying in porosity, crosslinking density, structure and crosslinker were fabricated. Collagen characterized by infrared spectroscopy and solution viscosity was determined to be pure and native. The collagen membranes were determined to possess native vs. non-native quaternary structure and porous vs. dense aggregate membranes by electron microscopy. Collagen monolithic devices containing a model macromolecule (inulin) were fabricated. In vitro release rates were found to be linear with respect to t 1/2 and were affected by crosslinking density, crosslinker and structure. The biodegradation of the collagen matrix was also examined. In vivo biocompatibility, degradation and 14 C-inulin release rates were evaluated subcutaneously in rats

  4. Central Corneal Thickness And Its Relationship To Intra-ocular And Epidemiological Determinants

    International Nuclear Information System (INIS)

    Tayyab, A.; Masrur, A.

    2016-01-01

    Objective: To measure central corneal thickness in Pakistani population and determine its relationship to intra-ocular pressure, age, gender and ethnicity. Study Design: Cross-sectional observation study. Place and Duration of Study: Pakistan Institute of Medical Sciences, Islamabad, Pakistan, between December 2013 and February 2015. Methodology: The right eyes of 1000 cases (496 males and 504 females) were recruited for this study. Inclusion criteria were Pashtun or Punjabi ethnicity, intra-ocular pressure < 22 mmHg, gonioscopically open angles, cup-disk-ratio < 0.5, and age matched normal visual fields. Cases with prior ocular surgery, contact lens use, corneal pathologies, myopia or hypermetropia > ±3.0 diopters, astigmatism of > ±1.0 diopters were excluded. Central corneal thickness was measured using a TopCon non-contact specular microscope. Intra-ocular pressure was measured using Goldmann applanation tonometer. Frequency distribution, test of significance, and regression analysis was carried out using Statistical Package for Social Sciences version 20.0. Result: Mean age was 47.31 ±11.78 years. Ethnic composition was 51.6 percentage (n=516) Pashtun and 48.4 percentage (n=484) Punjabi. The mean central corneal thickness was 503.96 (±12.47) meu m, while the mean intra-ocular pressure was 15.61 (±2.68) mmHg. Regression analysis showed a significant association between central corneal thickness and intra-ocular pressure (p=0.00) and age (p=0.00). A ±100 μ change in central corneal thickness was associated with change in IOP of ±3.30 mmHg, whereas central corneal thickness decreased by 0.12 meu m per year. No significant association could be established between central corneal thickness and ethnicity (p=0.19). Conclusion: Central corneal thickness of the studied races was comparable to non-Caucasians which affects intra-ocular pressure measurements, and decreases with increasing age. No relationship was observed between central corneal thickness and

  5. Collagens - structure, function and biosynthesis.

    OpenAIRE

    Gelse, K; Poschl, E; Aigner, T

    2003-01-01

    The extracellular matrix represents a complex alloy of variable members of diverse protein families defining structural integrity and various physiological functions. The most abundant family is the collagens with more than 20 different collagen types identified so far. Collagens are centrally involved in the formation of fibrillar and microfibrillar networks of the extracellular matrix, basement membranes as well as other structures of the extracellular matrix. This review focuses on the dis...

  6. IκB kinase β regulates epithelium migration during corneal wound healing.

    Directory of Open Access Journals (Sweden)

    Liang Chen

    2011-01-01

    Full Text Available The IKKβ is known to regulate transcription factor NF-κB activation leading to inflammatory responses. Recent gene knockout studies have shown that IKKβ can orchestrate local inflammatory responses and regulate homeostasis of epithelial tissues. To investigate whether IKKβ has an intrinsic role in epithelial cells, we established an in vivo system in the immune privileged corneal epithelium. We generated triple transgenic Krt12(rtTA/rtTAt/tet-O-Cre/Ikkβ(F/F (Ikkβ(ΔCE/ΔCE mice by crossing the Krt12-rtTA knock-in mice, which express the reverse tetracycline transcription activator in corneal epithelial cells, with the tet-O-Cre and Ikkβ(F/F mice. Doxycycline-induced IKKβ ablation occurred in corneal epithelial cells of triple transgenic Ikkβ(ΔCE/ΔCE mice, but loss of IKKβ did not cause ocular abnormalities in fetal development and postnatal maintenance. Instead, loss of IKKβ significantly delayed healing of corneal epithelial debridement without affecting cell proliferation, apoptosis or macrophage infiltration. In vitro studies with human corneal epithelial cells (HCEpi also showed that IKKβ was required for cytokine-induced cell migration and wound closure but was dispensable for cell proliferation. In both in vivo and in vitro settings, IKKβ was required for optimal activation of NF-κB and p38 signaling in corneal epithelial cells, and p38 activation is likely mediated through formation of an IKKβ-p38 protein complex. Thus, our studies in corneal epithelium reveal a previously un-recognized role for IKKβ in the control of epithelial cell motility and wound healing.

  7. Alloimmunity and Tolerance in Corneal Transplantation.

    Science.gov (United States)

    Amouzegar, Afsaneh; Chauhan, Sunil K; Dana, Reza

    2016-05-15

    Corneal transplantation is one of the most prevalent and successful forms of solid tissue transplantation. Despite favorable outcomes, immune-mediated graft rejection remains the major cause of corneal allograft failure. Although low-risk graft recipients with uninflamed graft beds enjoy a success rate ∼90%, the rejection rates in inflamed graft beds or high-risk recipients often exceed 50%, despite maximal immune suppression. In this review, we discuss the critical facets of corneal alloimmunity, including immune and angiogenic privilege, mechanisms of allosensitization, cellular and molecular mediators of graft rejection, and allotolerance induction. Copyright © 2016 by The American Association of Immunologists, Inc.

  8. Corneal iron ring after hyperopic photorefractive keratectomy.

    Science.gov (United States)

    Bilgihan, K; Akata, F; Gürelik, G; Adigüzel, U; Akpinar, M; Hasanreisoğlu, B

    1999-05-01

    To report the incidence and course of corneal iron deposition after hyperopic photorefractive keratectomy (PRK). Gazi University, Medical School, Department of Ophthalmology, Ankara, Turkey. Between January 1995 and December 1997, 62 eyes had PRK to correct hyperopia. Nine eyes developed corneal iron ring 5 to 8 months (mean 6.25 months +/- 1.3 [SD]) after PRK for hyperopia. The rings persisted during the mean follow-up of 19 +/- 11.09 months. The ring-shaped iron deposition after PRK for hyperopia must be differentiated from the Fleischer ring. Our results suggest that the slitlamp findings of peripheral corneal iron deposition in hyperopic PRK patients correlate with achieved correction.

  9. Investigation of the influence of UV irradiation on collagen thin films by AFM imaging

    International Nuclear Information System (INIS)

    Stylianou, Andreas; Yova, Dido; Alexandratou, Eleni

    2014-01-01

    Collagen is the major fibrous extracellular matrix protein and due to its unique properties, it has been widely used as biomaterial, scaffold and cell-substrate. The aim of the paper was to use Atomic Force Microscopy (AFM) in order to investigate well-characterized collagen thin films after ultraviolet light (UV) irradiation. The films were also used as in vitro culturing substrates in order to investigate the UV-induced alterations to fibroblasts. A special attention was given in the alteration on collagen D-periodicity. For short irradiation times, spectroscopy (fluorescence/absorption) studies demonstrated that photodegradation took place and AFM imaging showed alterations in surface roughness. Also, it was highlighted that UV-irradiation had different effects when it was applied on collagen solution than on films. Concerning fibroblast culturing, it was shown that fibroblast behavior was affected after UV irradiation of both collagen solution and films. Furthermore, after a long irradiation time, collagen fibrils were deformed revealing that collagen fibrils are consisting of multiple shells and D-periodicity occurred on both outer and inner shells. The clarification of the effects of UV light on collagen and the induced modifications of cell behavior on UV-irradiated collagen-based surfaces will contribute to the better understanding of cell–matrix interactions in the nanoscale and will assist in the appropriate use of UV light for sterilizing and photo-cross-linking applications. - Highlights: • Collagen thin films were formed and exposed in UV irradiation. • Collagen thin films were formed from UV-irradiated collagen solution. • Nanocharacterization of collagen thin films by AFM • Fluorescence and absorption spectroscopy studies on collagen films • Investigation of fibroblast response on collagen films

  10. Investigation of the influence of UV irradiation on collagen thin films by AFM imaging

    Energy Technology Data Exchange (ETDEWEB)

    Stylianou, Andreas, E-mail: styliand@mail.ntua.gr; Yova, Dido; Alexandratou, Eleni

    2014-12-01

    Collagen is the major fibrous extracellular matrix protein and due to its unique properties, it has been widely used as biomaterial, scaffold and cell-substrate. The aim of the paper was to use Atomic Force Microscopy (AFM) in order to investigate well-characterized collagen thin films after ultraviolet light (UV) irradiation. The films were also used as in vitro culturing substrates in order to investigate the UV-induced alterations to fibroblasts. A special attention was given in the alteration on collagen D-periodicity. For short irradiation times, spectroscopy (fluorescence/absorption) studies demonstrated that photodegradation took place and AFM imaging showed alterations in surface roughness. Also, it was highlighted that UV-irradiation had different effects when it was applied on collagen solution than on films. Concerning fibroblast culturing, it was shown that fibroblast behavior was affected after UV irradiation of both collagen solution and films. Furthermore, after a long irradiation time, collagen fibrils were deformed revealing that collagen fibrils are consisting of multiple shells and D-periodicity occurred on both outer and inner shells. The clarification of the effects of UV light on collagen and the induced modifications of cell behavior on UV-irradiated collagen-based surfaces will contribute to the better understanding of cell–matrix interactions in the nanoscale and will assist in the appropriate use of UV light for sterilizing and photo-cross-linking applications. - Highlights: • Collagen thin films were formed and exposed in UV irradiation. • Collagen thin films were formed from UV-irradiated collagen solution. • Nanocharacterization of collagen thin films by AFM • Fluorescence and absorption spectroscopy studies on collagen films • Investigation of fibroblast response on collagen films.

  11. Type II collagen C2C epitope in human synovial fluid and serum after knee injury

    DEFF Research Database (Denmark)

    Kumahashi, N; Swärd, P; Larsson, S

    2015-01-01

    PURPOSE: Investigate in a cross-sectional study time-dependent changes of synovial fluid type II collagen epitope C2C concentrations after knee injury and correlate to other joint injury biomarkers. METHODS: Synovial fluid samples were aspirated between 0 days and 7 years after injury (n = 235...... = 0.403, P type II collagen (r = 0.444, P = 0.003), ARGS-aggrecan (r = 0.337, P ... with an immediate and sustained local degradation of type II collagen....

  12. Double thermal transitions of type I collagen in acidic solution.

    Science.gov (United States)

    Liu, Yan; Liu, Lingrong; Chen, Mingmao; Zhang, Qiqing

    2013-01-01

    Contributed equally to this work. To further understand the origin of the double thermal transitions of collagen in acidic solution induced by heating, the denaturation of acidic soluble collagen was investigated by micro-differential scanning calorimeter (micro-DSC), circular dichroism (CD), dynamic laser light scattering (DLLS), transmission electron microscopy (TEM), and two-dimensional (2D) synchronous fluorescence spectrum. Micro-DSC experiments revealed that the collagen exhibited double thermal transitions, which were located within 31-37 °C (minor thermal transition, T(s) ∼ 33 °C) and 37-55 °C (major thermal transition, T(m) ∼ 40 °C), respectively. The CD spectra suggested that the thermal denaturation of collagen resulted in transition from polyproline II type structure to unordered structure. The DLLS results showed that there were mainly two kinds of collagen fibrillar aggregates with different sizes in acidic solution and the larger fibrillar aggregates (T(p2) = 40 °C) had better heat resistance than the smaller one (T(p1) = 33 °C). TEM revealed that the depolymerization of collagen fibrils occurred and the periodic cross-striations of collagen gradually disappeared with increasing temperature. The 2D fluorescence correlation spectra were also applied to investigate the thermal responses of tyrosine and phenylalanine residues at the molecular level. Finally, we could draw the conclusion that (1) the minor thermal transition was mainly due to the defibrillation of the smaller collagen fibrillar aggregates and the unfolding of a little part of triple helices; (2) the major thermal transition primarily arose from the defibrillation of the larger collagen fibrillar aggregates and the complete denaturation of the majority part of triple helices.

  13. Corneal Mechanical Thresholds Negatively Associate With Dry Eye and Ocular Pain Symptoms

    Science.gov (United States)

    Spierer, Oriel; Felix, Elizabeth R.; McClellan, Allison L.; Parel, Jean Marie; Gonzalez, Alex; Feuer, William J.; Sarantopoulos, Constantine D.; Levitt, Roy C.; Ehrmann, Klaus; Galor, Anat

    2016-01-01

    Purpose To examine associations between corneal mechanical thresholds and metrics of dry eye. Methods This was a cross-sectional study of individuals seen in the Miami Veterans Affairs eye clinic. The evaluation consisted of questionnaires regarding dry eye symptoms and ocular pain, corneal mechanical detection and pain thresholds, and a comprehensive ocular surface examination. The main outcome measures were correlations between corneal thresholds and signs and symptoms of dry eye and ocular pain. Results A total of 129 subjects participated in the study (mean age 64 ± 10 years). Mechanical detection and pain thresholds on the cornea correlated with age (Spearman's ρ = 0.26, 0.23, respectively; both P Dry eye symptom severity scores and Neuropathic Pain Symptom Inventory (modified for the eye) scores negatively correlated with corneal detection and pain thresholds (range, r = −0.13 to −0.27, P eye pain (pain to wind, light, temperature) and explained approximately 32% of measurement variability (R = 0.57). Conclusions Mechanical detection and pain thresholds measured on the cornea are correlated with dry eye symptoms and ocular pain. This suggests hypersensitivity within the corneal somatosensory pathways in patients with greater dry eye and ocular pain complaints. PMID:26886896

  14. Corneal Mechanical Thresholds Negatively Associate With Dry Eye and Ocular Pain Symptoms.

    Science.gov (United States)

    Spierer, Oriel; Felix, Elizabeth R; McClellan, Allison L; Parel, Jean Marie; Gonzalez, Alex; Feuer, William J; Sarantopoulos, Constantine D; Levitt, Roy C; Ehrmann, Klaus; Galor, Anat

    2016-02-01

    To examine associations between corneal mechanical thresholds and metrics of dry eye. This was a cross-sectional study of individuals seen in the Miami Veterans Affairs eye clinic. The evaluation consisted of questionnaires regarding dry eye symptoms and ocular pain, corneal mechanical detection and pain thresholds, and a comprehensive ocular surface examination. The main outcome measures were correlations between corneal thresholds and signs and symptoms of dry eye and ocular pain. A total of 129 subjects participated in the study (mean age 64 ± 10 years). Mechanical detection and pain thresholds on the cornea correlated with age (Spearman's ρ = 0.26, 0.23, respectively; both P Dry eye symptom severity scores and Neuropathic Pain Symptom Inventory (modified for the eye) scores negatively correlated with corneal detection and pain thresholds (range, r = -0.13 to -0.27, P eye pain (pain to wind, light, temperature) and explained approximately 32% of measurement variability (R = 0.57). Mechanical detection and pain thresholds measured on the cornea are correlated with dry eye symptoms and ocular pain. This suggests hypersensitivity within the corneal somatosensory pathways in patients with greater dry eye and ocular pain complaints.

  15. Correlating Corneal Biomechanics and Ocular Biometric Properties with Lamina Cribrosa Measurements in Healthy Subjects.

    Science.gov (United States)

    Pérez Bartolomé, Francisco; Martínez de la Casa, Jose María; Camacho Bosca, Irene; Sáenz-Francés, Federico; Aguilar Munoa, Soledad; Martín Juan, Alberto; Garcia-Feijoo, Julian

    2018-01-01

    To examine interrelations between corneal biomechanics, ocular biometric variables and optic disc size (ODS), lamina cribosa depth (LCD) or thickness (LCT) in a healthy population. In a cross-sectional case-control study, the following measurements were made in 81 eyes of 81 participants: axial length, anterior chamber depth, lens thickness, and central corneal thickness using the optical biometer Lenstar LS900; and corneal hysteresis (CH), corneal resistance factor (CRF), Goldman-correlated intraocular pressure (IOPg), and corneal-compensated IOP (IOPcc) using the Ocular Response Analyzer. Serial horizontal enhanced depth imaging optical coherence tomography (EDI OCT) B-scans of the optic nerve head were obtained in each participant. Mean ODS, mean LCD, and mean LCT were measured in 11 equally spaced horizontal B-scans, excluding the LC insertion area under Bruch's membrane and scleral rim. LCD was measured in 74 of 81 eyes (91.36%); LCT in 60/81 (75.3%); ODS in 81/81 (100%). CRF was poorly, but significantly, correlated with LCT (Pearson's R = 0.264; P = 0.045). IOPcc, IOPg, CH, and ocular biometrics variables were poorly (non-significantly) correlated with LCD, LCT, and ODS. CRF was poorly but directly correlated with LCT. No association was detected between CH or ocular biometric variables and ODS, LCD, or LCT.

  16. Central corneal thickness among glaucoma patients attending ...

    African Journals Online (AJOL)

    AAU_CHS

    ocular pressure measurement and is different among different ethnic population and subtypes of glaucoma. The central corneal thickness of different subtypes of glaucoma at Menelik II Hospital ... Intraocular pressure is a key element in the.

  17. Transforming growth factor-β2 induces morphological alteration of human corneal endothelial cells in vitro

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2014-10-01

    Full Text Available AIM:To investigate the morphological altering effect of transforming growth factor-β2 (TGF-β2 on untransfected human corneal endothelial cells (HCECs in vitro.METHODS: After untransfected HCECs were treated with TGF-β2 at different concentrations, the morphology, cytoskeleton distribution, and type IV collagen expression of the cells were examined with inverted contrast light microscopy, fluorescence microscopy, immunofluorescence or Western Blot.RESULTS:TGF-β2 at the concentration of 3-15 μg/L had obviously alterative effects on HCECs morphology in dose and time-dependent manner, and 9 μg/L was the peak concentration. TGF-β2 (9 μg/L altered HCE cell morphology after treatment for 36h, increased the mean optical density (P<0.01 and the length of F-actin, reduced the mean optical density (P<0.01 of the collagen type IV in extracellular matrix (ECM and induced the rearrangement of F-actin, microtubule in cytoplasm and collagen type IV in ECM after treatment for 72h. CONCLUTION:TGF-β2 has obviously alterative effect on the morphology of HCECs from polygonal phenotype to enlarged spindle-shaped phenotype, in dose and time-dependence manner by inducing more, elongation and alignment of F-actin, rearrangement of microtubule and larger spread area of collagen type IV.

  18. Cyclophilin B Deficiency Causes Abnormal Dentin Collagen Matrix.

    Science.gov (United States)

    Terajima, Masahiko; Taga, Yuki; Cabral, Wayne A; Nagasawa, Masako; Sumida, Noriko; Hattori, Shunji; Marini, Joan C; Yamauchi, Mitsuo

    2017-08-04

    Cyclophilin B (CypB) is an endoplasmic reticulum-resident protein that regulates collagen folding, and also contributes to prolyl 3-hydroxylation (P3H) and lysine (Lys) hydroxylation of collagen. In this study, we characterized dentin type I collagen in CypB null (KO) mice, a model of recessive osteogenesis imperfecta type IX, and compared to those of wild-type (WT) and heterozygous (Het) mice. Mass spectrometric analysis demonstrated that the extent of P3H in KO collagen was significantly diminished compared to WT/Het. Lys hydroxylation in KO was significantly diminished at the helical cross-linking sites, α1/α2(I) Lys-87 and α1(I) Lys-930, leading to a significant increase in the under-hydroxylated cross-links and a decrease in fully hydroxylated cross-links. The extent of glycosylation of hydroxylysine residues was, except α1(I) Lys-87, generally higher in KO than WT/Het. Some of these molecular phenotypes were distinct from other KO tissues reported previously, indicating the dentin-specific control mechanism through CypB. Histological analysis revealed that the width of predentin was greater and irregular, and collagen fibrils were sparse and significantly smaller in KO than WT/Het. These results indicate a critical role of CypB in dentin matrix formation, suggesting a possible association between recessive osteogenesis imperfecta and dentin defects that have not been clinically detected.

  19. Collagen Conduit Versus Microsurgical Neurorrhaphy

    DEFF Research Database (Denmark)

    Boeckstyns, Michel; Sørensen, Allan Ibsen; Viñeta, Joaquin Fores

    2013-01-01

    To compare repair of acute lacerations of mixed sensory-motor nerves in humans using a collagen tube versus conventional repair.......To compare repair of acute lacerations of mixed sensory-motor nerves in humans using a collagen tube versus conventional repair....

  20. Risk factors for corneal ectasia after LASIK.

    Science.gov (United States)

    Tabbara, Khalid F; Kotb, Amgad A

    2006-09-01

    To establish a grading system that helps identify high-risk individuals who may experience corneal ectasia after LASIK. Retrospective, comparative, interventional case series. One hundred forty-eight consecutive patients (148 eyes) were included in this study. Thirty-seven patients who underwent LASIK at other refractive centers experienced corneal ectasia in 1 eye after LASIK. One hundred eleven eyes of 111 patients who underwent successful LASIK during the same period were age and gender matched and served as controls. All patients underwent preoperative and postoperative topographic analysis of the cornea. The follow-up period in both groups of patients ranged from 2 to 5 years, with a mean follow-up of 3.6 years. All patients underwent LASIK for myopia (spherical equivalent, -4.00 to -8.00 diopters). Corneal keratometry, oblique cylinder, pachymetry, posterior surface elevation, difference between the inferior and superior corneal diopteric power, and posterior best sphere fit (BSF) over anterior BSF were given a grade of 1 to 3 each. An ectasia grading system was established, and the cumulative risk score was assessed. Patients who had a grade of 7 or less showed no evidence of corneal ectasia, whereas 16 (59%) of 27 patients who had a grade of 8 to 12 had corneal ectasia. Twenty-one (100%) of 21 patients with a grade of more than 12 had corneal ectasia after LASIK (P<0.0001). A risk score may help in the prediction of patients who are at risk of experiencing corneal ectasia after LASIK. A prospective clinical study is needed to assess the validity of these risk factors.

  1. Healed corneal ulcer with keloid formation

    OpenAIRE

    Alkatan, Hind M.; Al-Arfaj, Khalid M.; Hantera, Mohammed; Al-Kharashi, Soliman

    2012-01-01

    We are reporting a 34-year-old Arabic white female patient who presented with a white mass covering her left cornea following multiple ocular surgeries and healed corneal ulcer. The lesion obscured further view of the iris, pupil and lens. The patient underwent penetrating keratoplasty and the histopathologic study of the left corneal button showed epithelial hyperplasia, absent Bowman’s layer and subepithelial fibrovascular proliferation. The histopathologic appearance was suggestive of a co...

  2. Corneal elastosis within lattice dystrophy lesions.

    Science.gov (United States)

    Pe'er, J; Fine, B S; Dixon, A; Rothberg, D S

    1988-01-01

    Corneal buttons of two patients with lattice corneal dystrophy were studied by light and electron microscopy. They showed elastotic degeneration within the amyloid deposits. The amyloid deposits displayed characteristic staining; the elastotic material (elastin) within the deposits stained positive with Verhoeff-van Gieson and Movat pentachrome stains and showed autofluorescence. The characteristic ultrastructural findings of amyloid and elastotic material were also demonstrated. The possibility of the associations of these two materials in the cornea is discussed. Images PMID:3258531

  3. Intraocular pressure, corneal thickness, and corneal hysteresis in Steinert's myotonic dystrophy

    Directory of Open Access Journals (Sweden)

    Carlos Alexandre de A. Garcia Filho

    2011-06-01

    Full Text Available PURPOSE: Low intraocular pressure (IOP measured by Goldmann applanation tonometry (GAT is one of the ocular manifestations of Steinert's myotonic dystrophy. The goal of this study was to evaluate the corneal-compensated IOP as well as corneal properties (central corneal thickness and corneal hysteresis in patients with myotonic dystrophy. METHODS: A total of 12 eyes of 6 patients with Steinert's myotonic dystrophy (dystrophy group and 12 eyes of 6 age-, race-, and gender-matched healthy volunteers (control group were included in the study. GAT, Dynamic Contour Tonometry (DCT-Pascal and Ocular Response Analyzer (ORA were used to assess the IOP. Central corneal thickness was obtained by ultrasound pachymetry, and corneal hysteresis was analyzed using the ORA device. In light of the multiplicity of tests performed, the significance level was set at 0.01 rather than 0.05. RESULTS: The mean (standard deviation [SD] GAT, DCT, and corneal-compensated ORA IOP in the dystrophy group were 5.4 (1.4 mmHg, 9.7 (1.5 mmHg, and 10.1 (2.6 mmHg, respectively. The mean (SD GAT, DCT, and corneal-compensated ORA IOP in the control group was 12.6 (2.9 mmHg, 15.5 (2.7 mmHg, and 15.8 (3.4 mmHg, respectively. There were significant differences in IOP values between dystrophy and control groups obtained by GAT (mean, -7.2 mmHg; 99% confidence interval [CI], -10.5 to -3.9 mmHg; P<0.001, DCT (mean, -5.9 mmHg; 99% CI, -8.9 to -2.8 mmHg; P<0.001, and corneal-compensated ORA measurements (mean, -5.7 mmHg; 99% CI, -10.4 to -1.0 mmHg; P=0.003. The mean (SD central corneal thickness was similar in the dystrophy (542 [31] µm and control (537 [11] µm groups (P=0.65. The mean (SD corneal hysteresis in the dystrophy and control groups were 11.2 (1.5 mmHg and 9.7 (1.2 mmHg, respectively (P=0.04. CONCLUSIONS: Patients with Steinert's myotonic dystrophy showed lower Goldmann and corneal-compensated IOP in comparison with healthy individuals. Since central corneal thickness and

  4. The roles of TGF-beta1 gene transfer on collagen formation during Achilles tendon healing.

    Science.gov (United States)

    Hou, Yu; Mao, ZeBing; Wei, XueLei; Lin, Lin; Chen, LianXu; Wang, HaiJun; Fu, Xin; Zhang, JiYing; Yu, ChangLong

    2009-05-29

    Collagen content and cross-linking are believed to be major determinants of tendon structural integrity and function. The current study aimed to investigate the effects of transforming growth factor (TGF)-beta1 on the collagen content and cross-linking of Achilles tendons, and on the histological and biomechanical changes occurring during Achilles tendon healing in rabbits. Bone marrow-derived mesenchymal stem cells (BMSCs) transfected with the TGF-beta1 gene were surgically implanted into experimentally injured Achilles tendons. Collagen proteins were identified by immunohistochemical staining and fiber bundle accumulation was revealed by Sirius red staining. Achilles tendons treated with TGF-beta1-transfected BMSCs showed higher concentrations of collagen I protein, more rapid matrix remodeling, and larger fiber bundles. Thus TGF-beta1 can promote mechanical strength in healing Achilles tendons by regulating collagen synthesis, cross-link formation, and matrix remodeling.

  5. Fluorescence studies on the aggregation behaviors of collagen modified with NHS-activated poly(γ-glutamic acid).

    Science.gov (United States)

    Zhang, Min; Yang, Junhui; Yang, Qili; Huang, Liulian; Wu, Hui; Chen, Lihui; Ding, Cuicui

    2018-06-01

    The poly(γ-glutamic acid)-NHS (γ-PGA-NHS) esters were used to endow collagen with both of excellent water-solubility and thermal stability via cross-linking reaction between γ-PGA-NHS and collagen. In the present work, the effect of γ-PGA-NHS on the aggregation of collagen molecules was studied by fluorescence techniques. The fluorescence emission spectra of pyrene in collagen solutions and the intrinsic fluorescence emission spectra of collagen suggested different effects of γ-PGA-NHS on collagen molecules: inhibiting aggregation below critical aggregation concentration (CAC) and promoting aggregation above CAC. The two-dimensional (2D) fluorescence correlation spectra indicated that the intermolecular hydrogen bonding and cross-linking between γ-PGA-NHS and collagen would influence the aggregation of collagen molecules. By the ultra-sensitive differential scanning calorimeter (VP-DSC), it was found that the main denaturational transition temperature (T m2 ) of modified collagen increased, while its calorimetric enthalpy changes (ΔH 2 ) decreased compared to those of native collagen, further indicating that the modification of γ-PGA-NHS influenced the aggregation of collagen molecules. The study provide useful information for the utilizing and or the processing of water-soluble collagen in aqueous solution in the fields such as cosmetics, health care products, tissue engineering and biomedical materials, etc. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Chlorpromazine-induced corneal endothelial phototoxicity

    International Nuclear Information System (INIS)

    Hull, D.S.; Csukas, S.; Green, K.

    1982-01-01

    Chlorpromazine, which has been used extensively for the treatment of psychiatric disorders, is known to accumulate in the posterior corneal stroma, lens, and uveal tract. Because it is a phototoxic compound, the potential exists for it to cause cellular damage after light exposure. Specular microscopic perfusion of corneal endothelial cells in darkness with 0.5 mM chlorpromazine HCl resulted in a swelling rate of 18 +/- 2 micrometer/hr, whereas corneas exposed to long-wavelength ultraviolet light for 3 min in the presence of 0.5 mM chlorpromazine swelled at 37 +/- 9 micrometer/hr (p less than 0.01). Preirradiation of 0.5 mM chlorpromazine solution with ultraviolet light for 30 min and subsequent corneal perfusion with the solution resulted in a corneal swelling rate of 45 +/- 19 micrometer/hr. Cornea endothelial cells perfused with 0.5 mM chlorpromazine that was preirradiated with ultraviolet light showed marked swelling on scanning electron microscopic examination, whereas those perfused with nonirradiated chlorpromazine were flat and showed a normal mosaic pattern. Combining either 500 U/ml catalase or 290 U/ml superoxide dismutase with chlorpromazine did not alter photoinduction of corneal swelling. The data suggest that corneal endothelial chlorpromazine phototoxicity is secondary to cytotoxic products resulting from the photodynamically induced decomposition of chlorpromazine and is not caused by hydrogen peroxide or superoxide anion generated during the phototoxic reaction

  7. Experimental Models for Investigating Intra-Stromal Migration of Corneal Keratocytes, Fibroblasts and Myofibroblasts

    Directory of Open Access Journals (Sweden)

    Lisha Ma

    2012-03-01

    Full Text Available Following laser vision correction, corneal keratocytes must repopulate areas of cell loss by migrating through the intact corneal stroma, and this can impact corneal shape and transparency. In this study, we evaluate 3D culture models for simulating this process in vitro. Buttons (8 mm diameter were first punched out of keratocyte populated compressed collagen matrices, exposed to a 3 mm diameter freeze injury, and cultured in serum-free media (basal media or media supplemented with 10% FBS, TGFb1 or PDGF BB. Following freeze injury, a region of cell death was observed in the center of the constructs. Although cells readily migrated on top of the matrices to cover the wound area, a limited amount of cell migration was observed within the constructs. We next developed a novel “sandwich” model, which better mimics the native lamellar architecture of the cornea. Using this model, significant migration was observed under all conditions studied. In both models, cells in TGFb and 10% FBS developed stress fibers; whereas cells in PDGF were more dendritic. PDGF stimulated the most inter-lamellar migration in the sandwich construct. Overall, these models provide insights into the complex interplay between growth factors, cell mechanical phenotypes and the structural properties of the ECM.

  8. The digestion of phagocytosed collagen is inhibited by the proteinase inhibitors leupeptin and E-64

    NARCIS (Netherlands)

    Everts, V.; Beertsen, W.; Tigchelaar-Gutter, W.

    1985-01-01

    Using morphometric methods the effects of the thiol-proteinase inhibitors leupeptin and E-64 on the digestion of intracytoplasmic collagen fibrils were studied in cultured mouse bone explants. Both drugs caused a dose-dependent increase of lysosomal structures containing cross-banded collagen

  9. Collagen Fiber Orientation in Primate Long Bones.

    Science.gov (United States)

    Warshaw, Johanna; Bromage, Timothy G; Terranova, Carl J; Enlow, Donald H

    2017-07-01

    Studies of variation in orientation of collagen fibers within bone have lead to the proposition that these are preferentially aligned to accommodate different kinds of load, with tension best resisted by fibers aligned longitudinally relative to the load, and compression best resisted by transversely aligned fibers. However, previous studies have often neglected to consider the effect of developmental processes, including constraints on collagen fiber orientation (CFO), particularly in primary bone. Here we use circularly polarized light microscopy to examine patterns of CFO in cross-sections from the midshaft femur, humerus, tibia, radius, and ulna in a range of living primate taxa with varied body sizes, phylogenetic relationships and positional behaviors. We find that a preponderance of longitudinally oriented collagen is characteristic of both periosteal primary and intracortically remodeled bone. Where variation does occur among groups, it is not simply understood via interpretations of mechanical loads, although prioritized adaptations to tension and/or shear are considered. While there is some suggestion that CFO may correlate with body size, this relationship is neither consistent nor easily explicable through consideration of size-related changes in mechanical adaptation. The results of our study indicate that there is no clear relationship between CFO and phylogenetic status. One of the principle factors accounting for the range of variation that does exist is primary tissue type, where slower depositing bone is more likely to comprise a larger proportion of oblique to transverse collagen fibers. Anat Rec, 300:1189-1207, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  10. Targeted decorin gene therapy delivered with adeno-associated virus effectively retards corneal neovascularization in vivo.

    Directory of Open Access Journals (Sweden)

    Rajiv R Mohan

    Full Text Available Decorin, small leucine-rich proteoglycan, has been shown to modulate angiogenesis in nonocular tissues. This study tested a hypothesis that tissue-selective targeted decorin gene therapy delivered to the rabbit stroma with adeno-associated virus serotype 5 (AAV5 impedes corneal neovascularization (CNV in vivo without significant side effects. An established rabbit CNV model was used. Targeted decorin gene therapy in the rabbit stroma was delivered with a single topical AAV5 titer (100 µl; 5×10(12 vg/ml application onto the stroma for two minutes after removing corneal epithelium. The levels of CNV were examined with stereomicroscopy, H&E staining, lectin, collagen type IV, CD31 immunocytochemistry and CD31 immunoblotting. Real-time PCR quantified mRNA expression of pro- and anti-angiogenic genes. Corneal health in live animals was monitored with clinical, slit-lamp and optical coherence tomography biomicroscopic examinations. Selective decorin delivery into stroma showed significant 52% (p<0.05, 66% (p<0.001, and 63% (p<0.01 reduction at early (day 5, mid (day 10, and late (day 14 stages of CNV in decorin-delivered rabbit corneas compared to control (no decorin delivered corneas in morphometric analysis. The H&E staining, lectin, collagen type IV, CD31 immunostaining (57-65, p<0.5, and CD31 immunoblotting (62-67%, p<0.05 supported morphometric findings. Quantitative PCR studies demonstrated decorin gene therapy down-regulated expression of VEGF, MCP1 and angiopoietin (pro-angiogenic and up-regulated PEDF (anti-angiogenic genes. The clinical, biomicroscopy and transmission electron microscopy studies revealed that AAV5-mediated decorin gene therapy is safe for the cornea. Tissue-targeted AAV5-mediated decorin gene therapy decreases CNV with no major side effects, and could potentially be used for treating patients.

  11. Newly identified interfibrillar collagen crosslinking suppresses cell proliferation and remodelling.

    Science.gov (United States)

    Marelli, Benedetto; Le Nihouannen, Damien; Hacking, S Adam; Tran, Simon; Li, Jingjing; Murshed, Monzur; Doillon, Charles J; Ghezzi, Chiara E; Zhang, Yu Ling; Nazhat, Showan N; Barralet, Jake E

    2015-06-01

    Copper is becoming recognised as a key cation in a variety of biological processes. Copper chelation has been studied as a potential anti-angiogenic strategy for arresting tumour growth. Conversely the delivery of copper ions and complexes in vivo can elicit a pro-angiogenic effect. Previously we unexpectedly found that copper-stimulated intraperitoneal angiogenesis was accompanied by collagen deposition. Here, in hard tissue, not only was healing accelerated by copper, but again enhanced deposition of collagen was detected at 2 weeks. Experiments with reconstituted collagen showed that addition of copper ions post-fibrillogenesis rendered plastically-compressed gels resistant to collagenases, enhanced their mechanical properties and increased the denaturation temperature of the protein. Unexpectedly, this apparently interfibrillar crosslinking was not affected by addition of glucose or ascorbic acid, which are required for crosslinking by advanced glycation end products (AGEs). Fibroblasts cultured on copper-crosslinked gels did not proliferate, whereas those cultured with an equivalent quantity of copper on either tissue culture plastic or collagen showed no effect compared with controls. Although non-proliferative, fibroblasts grown on copper-cross-linked collagen could migrate, remained metabolically active for at least 14 days and displayed a 6-fold increase in Mmps 1 and 3 mRNA expression compared with copper-free controls. The ability of copper ions to crosslink collagen fibrils during densification and independently of AGEs or Fenton type reactions is previously unreported. The effect on MMP susceptibility of collagen and the dramatic change in cell behaviour on this crosslinked ECM may contribute to shedding some light on unexplained phenomena as the apparent benefit of copper complexation in fibrotic disorders or the enhanced collagen deposition in response to localised copper delivery. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. The synthesis and coupling of photoreactive collagen-based peptides to restore integrin reactivity to an inert substrate, chemically-crosslinked collagen

    Science.gov (United States)

    Malcor, Jean-Daniel; Bax, Daniel; Hamaia, Samir W.; Davidenko, Natalia; Best, Serena M.; Cameron, Ruth E.; Farndale, Richard W.; Bihan, Dominique

    2016-01-01

    Collagen is frequently advocated as a scaffold for use in regenerative medicine. Increasing the mechanical stability of a collagen scaffold is widely achieved by cross-linking using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS). However, this treatment consumes the carboxylate-containing amino acid sidechains that are crucial for recognition by the cell-surface integrins, abolishing cell adhesion. Here, we restore cell reactivity to a cross-linked type I collagen film by covalently linking synthetic triple-helical peptides (THPs), mimicking the structure of collagen. These THPs are ligands containing an active cell-recognition motif, GFOGER, a high-affinity binding site for the collagen-binding integrins. We end-stapled peptide strands containing GFOGER by coupling a short diglutamate-containing peptide to their N-terminus, improving the thermal stability of the resulting THP. A photoreactive Diazirine group was grafted onto the end-stapled THP to allow covalent linkage to the collagen film upon UV activation. Such GFOGER-derivatized collagen films showed restored affinity for the ligand-binding I domain of integrin α2β1, and increased integrin-dependent cell attachment and spreading of HT1080 and Rugli cell lines, expressing integrins α2β1 and α1β1, respectively. The method we describe has wide application, beyond collagen films or scaffolds, since the photoreactive diazirine will react with many organic carbon skeletons. PMID:26854392

  13. Details of the Collagen and Elastin Architecture in the Human Limbal Conjunctiva, Tenon's Capsule and Sclera Revealed by Two-Photon Excited Fluorescence Microscopy.

    Science.gov (United States)

    Park, Choul Yong; Marando, Catherine M; Liao, Jason A; Lee, Jimmy K; Kwon, Jiwon; Chuck, Roy S

    2016-10-01

    To investigate the architecture and distribution of collagen and elastin in human limbal conjunctiva, Tenon's capsule, and sclera. The limbal conjunctiva, Tenon's capsule, and sclera of human donor corneal buttons were imaged with an inverted two-photon excited fluorescence microscope. No fixation process was necessary. The laser (Ti:sapphire) was tuned at 850 nm for two-photon excitation. Backscatter signals of second harmonic generation (SHG) and autofluorescence (AF) were collected through a 425/30-nm and a 525/45-nm emission filter, respectively. Multiple, consecutive, and overlapping (z-stack) images were acquired. Collagen signals were collected with SHG, whereas elastin signals were collected with AF. The size and density of collagen bundles varied widely depending on depth: increasing from conjunctiva to sclera. In superficial image planes, collagen bundles were image planes (episclera and superficial sclera), collagen bundles were thicker (near 100 μm in width) and densely packed. Comparatively, elastin fibers were thinner and sparse. The orientation of elastin fibers was independent of collagen fibers in superficial layers; but in deep sclera, elastin fibers wove through collagen interbundle gaps. At the limbus, both collagen and elastin fibers were relatively compact and were distributed perpendicular to the limbal annulus. Two-photon excited fluorescence microscopy has enabled us to understand in greater detail the collagen and elastin architecture of the human limbal conjunctiva, Tenon's capsule, and sclera.

  14. Development of a monoclonal antibody to urinary degradation products from the C-terminal telopeptide alpha 1 chain of type I collagen. Application in an enzyme Immunoassay and comparison to CrossLaps(TM) ELISA

    DEFF Research Database (Denmark)

    C, Fledelius; I, Kolding; P, Quist

    1997-01-01

    A monoclonal antibody MAbA7 was raised against a synthetic peptide having a sequence (EKAHDGGR) specific for a part of the C-telopeptide alpha 1 chain of type I collagen. MAbA7 was labelled with horseradish peroxide and used in a competitive one-step enzyme-linked immunosorbent assay (ELISA...... concentrations decreased 88% (pantibody and the new assay may be useful for further investigations of the physiological...

  15. Instillation of Sericin Enhances Corneal Wound Healing through the ERK Pathway in Rat Debrided Corneal Epithelium

    Directory of Open Access Journals (Sweden)

    Noriaki Nagai

    2018-04-01

    Full Text Available Sericin is a major constituent of silk produced by silkworms. We previously found that the instillation of sericin enhanced the proliferation of corneal epithelial cells, and acted to promote corneal wound healing in both normal and diabetic model rats. However, the mechanisms by which sericin promotes the proliferation of corneal cells have not been established. In this study, we investigated the effects of sericin on Akt and ERK activation in a human corneal epithelial cell line (HCE-T cells and rat debrided corneal epithelium. Although Akt phosphorylation was not detected following the treatment of HCE-T cells with sericin, ERK1/2 phosphorylation was enhanced. The growth of HCE-T cells treated with sericin was significantly increased, with the cell growth of sericin-treated HCE-T cells being 1.7-fold higher in comparison with vehicle-treated HCE-T cells. On the other hand, both of an ERK inhibitor U0126 (non-specific specific inhibitor and SCH772984 (specific inhibitor attenuated the enhanced cell growth by sericin, and the growth level in the case of co-treatment with sericin and ERK1/2 inhibitor was similar to that of cells treated with ERK1/2 inhibitor alone. In an in vivo study using rat debrided corneal epithelium, the corneal wound healing rate was enhanced by the instillation of sericin, and this enhancement was also attenuated by the instillation of U0126. In addition, the corneal wound healing rate in rats co-instilled with sericin and U0126 was similar to that following the instillation of U0126 alone. In conclusion, we found that the instillation of sericin enhanced cell proliferation via the activation of the MAPK/ERK pathway, resulting in the promotion of corneal wound healing in rat eyes. These findings provide significant information for designing further studies to develop potent corneal wound-healing drugs.

  16. Controlling human corneal stromal stem cell contraction to mediate rapid cell and matrix organization of real architecture for 3-dimensional tissue equivalents.

    Science.gov (United States)

    Mukhey, Dev; Phillips, James B; Daniels, Julie T; Kureshi, Alvena K

    2018-02-01

    The architecture of the human corneal stroma consists of a highly organized extracellular matrix (ECM) interspersed with keratocytes. Their progenitor cells; corneal stromal stem cells (CSSC) are located at the periphery, in the limbal stroma. A highly organized corneal ECM is critical for effective transmission of light but this structure may be compromised during injury or disease, resulting in loss of vision. Re-creating normal organization in engineered tissue equivalents for transplantation often involves lengthy culture times that are inappropriate for clinical use or utilisation of synthetic substrates that bring complications such as corneal melting. CSSC have great therapeutic potential owing to their ability to reorganize a disorganized matrix, restoring transparency in scarred corneas. We examined CSSC contractile behavior to assess whether this property could be exploited to rapidly generate cell and ECM organization in Real Architecture For 3D Tissues (RAFT) tissue equivalents (TE) for transplantation. Free-floating collagen gels were characterized to assess contractile behavior of CSSC and establish optimum cell density and culture times. To mediate cell and collagen organization, tethered collagen gels seeded with CSSC were cultured and subsequently stabilized with the RAFT process. We demonstrated rapid creation of biomimetic RAFT TE with tunable structural properties. These displayed three distinct regions of varying degrees of cellular and collagen organization. Interestingly, increased organization coincided with a dramatic loss of PAX6 expression in CSSC, indicating rapid differentiation into keratocytes. The organized RAFT TE system could be a useful bioengineering tool to rapidly create an organized ECM while simultaneously controlling cell phenotype. For the first time, we have demonstrated that human CSSC exhibit the phenomenon of cellular self-alignment in tethered collagen gels. We found this mediated rapid co-alignment of collagen fibrils

  17. A collagen-binding EGFR antibody fragment targeting tumors with a collagen-rich extracellular matrix

    OpenAIRE

    Hui Liang; Xiaoran Li; Bin Wang; Bing Chen; Yannan Zhao; Jie Sun; Yan Zhuang; Jiajia Shi; He Shen; Zhijun Zhang; Jianwu Dai

    2016-01-01

    Many tumors over-express collagen, which constitutes the physical scaffold of tumor microenvironment. Collagen has been considered to be a target for cancer therapy. The collagen-binding domain (CBD) is a short peptide, which could bind to collagen and achieve the sustained release of CBD-fused proteins in collagen scaffold. Here, a collagen-binding EGFR antibody fragment was designed and expressed for targeting the collagen-rich extracellular matrix in tumors. The antibody fragment (Fab) of ...

  18. Human tears reveal insights into corneal neovascularization.

    Science.gov (United States)

    Zakaria, Nadia; Van Grasdorff, Sigi; Wouters, Kristien; Rozema, Jos; Koppen, Carina; Lion, Eva; Cools, Nathalie; Berneman, Zwi; Tassignon, Marie-José

    2012-01-01

    Corneal neovascularization results from the encroachment of blood vessels from the surrounding conjunctiva onto the normally avascular cornea. The aim of this study is to identify factors in human tears that are involved in development and/or maintenance of corneal neovascularization in humans. This could allow development of diagnostic tools for monitoring corneal neovascularization and combination monoclonal antibody therapies for its treatment. In an observational case-control study we enrolled a total of 12 patients with corneal neovascularization and 10 healthy volunteers. Basal tears along with reflex tears from the inferior fornix, superior fornix and using a corneal bath were collected along with blood serum samples. From all patients, ocular surface photographs were taken. Concentrations of the pro-angiogenic cytokines interleukin (IL)-6, IL-8, Vascular Endothelial Growth Factor (VEGF), Monocyte Chemoattractant Protein 1 (MCP-1) and Fas Ligand (FasL) were determined in blood and tear samples using a flow cytometric multiplex assay. Our results show that the concentration of pro-angiogenic cytokines in human tears are significantly higher compared to their concentrations in serum, with highest levels found in basal tears. Interestingly, we could detect a significantly higher concentration of IL- 6, IL-8 and VEGF in localized corneal tears of patients with neovascularized corneas when compared to the control group. This is the first study of its kind demonstrating a significant difference of defined factors in tears from patients with neovascularized corneas as compared to healthy controls. These results provide the basis for future research using animal models to further substantiate the role of these cytokines in the establishment and maintenance of corneal neovascularization.

  19. Lysyl oxidases regulate fibrillar collagen remodelling in idiopathic pulmonary fibrosis

    NARCIS (Netherlands)

    Tjin, Gavin; White, Eric S; Faiz, Alen; Sicard, Delphine; Tschumperlin, Daniel J; Mahar, Annabelle; Kable, Eleanor P W; Burgess, Janette K

    2017-01-01

    Idiopathic pulmonary fibrosis (IPF) is a progressive scarring disease of the lung with feweffective therapeutic options. Structural remodelling of the extracellular matrix [i.e. collagen cross-linkingmediated by the lysyl oxidase (LO) family of enzymes (LOX, LOXL1-4)] might contribute to disease

  20. Regeneration of defective epithelial basement membrane and restoration of corneal transparency

    Science.gov (United States)

    Marino, Gustavo K.; Santhiago, Marcony R.; Santhanam, Abirami; Torricelli, Andre A. M.; Wilson, Steven E.

    2018-01-01

    PURPOSE To study regeneration of the normal ultrastructure of the epithelial basement membrane (EBM) in rabbit corneas that had -9D photorefractive keratectomy (PRK) and developed late haze (fibrosis) with restoration of transparency over one to four months after surgery and in corneas that had incisional wounds. METHODS Twenty-four rabbits had one of their eyes included into one of the two procedure groups (-9D PRK or nearly full-thickness incisional wounds), while the opposite eye serving as unwounded controls. All corneas were evaluated with slit lamp photos, transmission electron microscopy and immunohistochemistry for the myofibroblast marker alpha-smooth muscle actin and collagen type III. RESULTS In the ‘-9D PRK group’, corneas at one month after surgery had dense corneal haze and no evidence of regenerated EBM ultrastructure. By two months after surgery, however, small areas of stromal clearing began to appear within the confluent opacity (lacunae), and these corresponded to small islands of normally-regenerated EBM detected within larger area of the excimer laser-ablated zone with no evidence of normal EBM. By four months after surgery, the EBM was fully-regenerated and the corneal transparency was completely restored to the ablated zone. In the ‘Incisional wound group’, the two dense, linear corneal opacities were observed at one month after surgery and progressively faded by two and three months after surgery. The EBM ultrastructure was fully regenerated at the site of the incisions, including around epithelial plugs that extended into the stroma, by one month after surgery in all eyes. CONCLUSIONS In the rabbit model, spontaneous resolution of corneal fibrosis (haze) after high correction PRK is triggered by regeneration of EBM with normal ultrastructure in the excimer laser- ablated zone. Conversely, incisional wounds heal in rabbit corneas without the development of myofibroblasts because the EBM regenerates normally by one month after surgery

  1. Corneal endothelial cell density and morphology in patients with acromegaly.

    Science.gov (United States)

    Hatipoglu, Esra; Arici, Ceyhun; Arslan, Osman Sevki; Dikkaya, Funda; Sultan, Pinar; Kadioglu, Pinar; Gundogdu, Sadi

    2014-12-01

    Acromegaly has various impacts on many organs. The ophthalmologic effects of acromegaly have not yet been investigated in detail. The aim of the current study was to evaluate qualitative and quantitative changes in corneal endothelial cells and central corneal thickness (CCT) of the patients with acromegaly. In this prospective, cross-sectional study, 128 eyes of 64 patients with acromegaly (female/male=40/24) and 208 eyes of 104 age and gender-matched healthy volunteers (female/male=69/35) were included. Endothelial cell density (ECD), cellular area (CA), coefficient of variation (CV) in cell size, percentage of hexagonal cells, and CCT were measured in patients with acromegaly and in healthy volunteers using the noncontact specular microscopy (SP-3000P: Topcon Corporation, Tokyo, Japan). ECD and CA were lower in cases with acromegaly than in controls (ECD in acromegaly: 2615.65 cell/mm(2) and in controls: 2700.35 cell/mm(2); p=0.002. CA in acromegaly: 382.30μm(2) and in controls: 400.30μm(2); p=0.02). In the entire group with acromegaly, the time elapsed since diagnosis was positively correlated with CA and was negatively correlated with ECD (r=+0.39, p=0.001 and r=-0.42, p=0.001). The endothelial layer of the cornea may be under risk of impairment with prolonged disease duration in acromegaly. Consistency of the corneal endothelium should be also sought during long-term follow-up of the cases with acromegaly. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Disorganized collagen scaffold interferes with fibroblast mediated deposition of organized extracellular matrix in vitro.

    Science.gov (United States)

    Saeidi, Nima; Guo, Xiaoqing; Hutcheon, Audrey E K; Sander, Edward A; Bale, Shyam Sundar; Melotti, Suzanna A; Zieske, James D; Trinkaus-Randall, Vickery; Ruberti, Jeffrey W

    2012-10-01

    Many tissue engineering applications require the remodeling of a degradable scaffold either in vitro or in situ. Although inefficient remodeling or failure to fully remodel the temporary matrix can result in a poor clinical outcome, very few investigations have examined in detail, the interaction of regenerative cells with temporary scaffoldings. In a recent series of investigations, randomly oriented collagen gels were directly implanted into human corneal pockets and followed for 24 months. The resulting remodeling response exhibited a high degree of variability which likely reflects differing regenerative/synthetic capacity across patients. Given this variability, we hypothesize that a disorganized, degradable provisional scaffold could be disruptive to a uniform, organized reconstruction of stromal matrix. In this investigation, two established corneal stroma tissue engineering culture systems (collagen scaffold-based and scaffold-free) were compared to determine if the presence of the disorganized collagen gel influenced matrix production and organizational control exerted by primary human corneal fibroblast cells (PHCFCs). PHCFCs were cultured on thin disorganized reconstituted collagen substrate (RCS--five donors: average age 34.4) or on a bare polycarbonate membrane (five donors: average age 32.4 controls). The organization and morphology of the two culture systems were compared over the long-term at 4, 8, and 11/12 weeks. Construct thickness and extracellular matrix organization/alignment was tracked optically with bright field and differential interference contrast (DIC) microscopy. The details of cell/matrix morphology and cell/matrix interaction were examined with standard transmission, cuprolinic blue and quick-freeze/deep-etch electron microscopy. Both the scaffold-free and the collagen-based scaffold cultures produced organized arrays of collagen fibrils. However, at all time points, the amount of organized cell-derived matrix in the scaffold

  3. Contact lens rehabilitation following repaired corneal perforations

    Science.gov (United States)

    Titiyal, Jeewan S; Sinha, Rajesh; Sharma, Namrata; Sreenivas, V; Vajpayee, Rasik B

    2006-01-01

    Background Visual outcome following repair of post-traumatic corneal perforation may not be optimal due to presence of irregular keratometric astigmatism. We performed a study to evaluate and compare rigid gas permeable contact lens and spectacles in visual rehabilitation following perforating corneal injuries. Method Eyes that had undergone repair for corneal perforating injuries with or without lens aspiration were fitted rigid gas permeable contact lenses. The fitting pattern and the improvement in visual acuity by contact lens over spectacle correction were noted. Results Forty eyes of 40 patients that had undergone surgical repair of posttraumatic corneal perforations were fitted rigid gas permeable contact lenses for visual rehabilitation. Twenty-four eyes (60%) required aphakic contact lenses. The best corrected visual acuity (BCVA) of ≥ 6/18 in the snellen's acuity chart was seen in 10 (25%) eyes with spectacle correction and 37 (92.5%) eyes with the use of contact lens (p < 0.001). The best-corrected visual acuity with spectacles was 0.20 ± 0.13 while the same with contact lens was 0.58 ± 0.26. All the patients showed an improvement of ≥ 2 lines over spectacles in the snellen's acuity chart with contact lens. Conclusion Rigid gas permeable contact lenses are better means of rehabilitation in eyes that have an irregular cornea due to scars caused by perforating corneal injuries. PMID:16536877

  4. Bone Collagen: New Clues to its Mineralization Mechanism From Recessive Osteogenesis Imperfecta

    Science.gov (United States)

    Eyre, David R.; Ann Weis, Mary

    2013-01-01

    Until 2006 the only mutations known to cause osteogenesis imperfecta (OI) were in the two genes coding for type I collagen chains. These dominant mutations affecting the expression or primary sequence of collagen α1(I) and α2(I) chains account for over 90% of OI cases. Since then a growing list of mutant genes causing the 5–10% of recessive cases has rapidly emerged. They include CRTAP, LEPRE1 and PPIB, which encode three proteins forming the prolyl 3-hydroxylase complex; PLOD2 and FKBP10, which encode respectively lysyl hydroxylase 2 and a foldase required for its activity in forming mature cross-links in bone collagen; SERPIN H1, which encodes the collagen chaperone HSP47; SERPIN F1, which encodes pigment epithelium-derived factor required for osteoid mineralization; and BMP1, which encodes the type I procollagen C-propeptidase. All cause fragile bone in infancy, which can include over-mineralization or under-mineralization defects as well as abnormal collagen post-translational modifications. Consistently both dominant and recessive variants lead to abnormal cross-linking chemistry in bone collagen. These recent discoveries strengthen the potential for a common pathogenic mechanism of misassembled collagen fibrils. Of the new genes identified, eight encode proteins required for collagen post-translational modification, chaperoning of newly synthesized collagen chains into native molecules or transport through the endoplasmic reticulum and Golgi for polymerization, cross-linking and mineralization. In reviewing these findings, we conclude that a common theme is emerging in the pathogenesis of brittle bone disease of mishandled collagen assembly with important insights on post-translational features of bone collagen that have evolved to optimize it as a biomineral template. PMID:23508630

  5. Efficacy of Tectonic Corneal Patch Graft for Progressive Peripheral Corneal Thinning

    Directory of Open Access Journals (Sweden)

    Cafer Tanrıverdio

    2014-12-01

    Full Text Available Objectives: To report the results of tectonic corneal patch graft (TCPG in patients with progressive peripheral corneal thinning (PCT. Materials and Methods: In this study, we included 8 patients who underwent TCPG for PCT or perforated corneal ulceration at Ankara Training and Research Hospital. Results: We performed TCPG in 7 patients for PCT and in 1 patient for perforated corneal ulceration. Mean age was 57.2±16.7 (38- 82 years. Postoperative follow-up time ranged from 6 to 24 months (mean 13.9±6.7. Possible etiologies leading to progressive PCT were trachoma, infectious corneal ulcer, and rheumatoid arthritis-severe dry eye in 2 patients each. Other 2 patients had a progressive PCT following ocular surgery. One of the patients with infectious corneal ulcer also had a trauma caused by a scissor. Amnion membrane transplantation was performed in 3 patients prior to TCPG. While the anatomic success was achieved in all 8 patients, best-corrected visual acuity (BCVA was 0.1 or better in 4 patients (50%. Postoperative BCVA was better than preoperative BCVA in 6 patients (75%. Local peripheral anterior synechiae developed in two eyes. Conclusion: TCPG is a useful therapeutic option in selected cases of corneal thinning and perforations because it effectively restores the integrity of the globe and allows acceptable visual results. (Turk J Ophthalmol 2014; 44: 440-4

  6. Analysis of the horizontal corneal diameter, central corneal thickness, and axial length in premature infants

    Directory of Open Access Journals (Sweden)

    Ozdemir Ozdemir

    2014-08-01

    Full Text Available Purpose: To determine the horizontal corneal diameter, central corneal thickness, and axial length in premature infants. Methods: Infants with a birth weight of less than 2,500 g or with a gestation period of less than 36 weeks were included in the study. Infants with retinopathy of prematurity (ROP were allocated to Group 1 (n=138, while those without ROP were allocated to Group 2 (n=236. All infants underwent a complete ophthalmologic examination, including corneal diameter measurements, pachymetry, biometry, and fundoscopy. Between-group comparisons of horizontal corneal diameter, central corneal thickness, and axial lengths were performed. Independent sample t-tests were used for statistical analysis. Results: Data was obtained from 374 eyes of 187 infants (102 female, 85 male. The mean gestational age at birth was 30.7 ± 2.7 weeks (range 25-36 weeks, the mean birth weight was 1,514 ± 533.3 g (range 750-1,970 g, and the mean postmenstrual age at examination was 40.0 ± 4.8 weeks. The mean gestational age and the mean birth weight of Group 1 were statistically lower than Group 2 (p0.05. Conclusions: The presence of ROP in premature infants does not alter the horizontal corneal diameter, central corneal thickness, or axial length.

  7. Keratocyte apoptosis and corneal antioxidant enzyme activities after refractive corneal surgery.

    Science.gov (United States)

    Bilgihan, K; Bilgihan, A; Adiguzel, U; Sezer, C; Yis, O; Akyol, G; Hasanreisoglu, B

    2002-01-01

    Refractive corneal surgery induces keratocyte apoptosis and generates reactive oxygen radicals (ROS) in the cornea. The purpose of the present study is to evaluate the correlation between keratocyte apoptosis and corneal antioxidant enzyme activities after different refractive surgical procedures in rabbits. Rabbits were divided into six groups. All groups were compared with the control group (Group 1), after epithelial scraping (Group 2), epithelial scrape and photorefractive keratectomy (PRK) (traditional PRK: Group 3), transepithelial PRK (Group 4), creation of a corneal flap with microkeratome (Group 5) and laser-assisted in situ keratomileusis (LASIK, Group 6). Terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labelling assay (to detect DNA fragmentation in situ) and light microscopy were used to detect apoptosis in rabbit eyes. Glutathione peroxidase (Gpx) and superoxide dismutase (SOD) activities of the corneal tissues were measured with spectrophotometric methods. Corneal Gpx and SOD activities decreased significantly in all groups when compared with the control group (P<0.05) and groups 2, 3 and 6 showed a significantly higher amount of keratocyte apoptosis (P<0.05). Not only a negative correlation was observed between corneal SOD activity and keratocyte apoptosis (cc: -0.3648) but Gpx activity also showed negative correlation with keratocyte apoptosis (cc: -0.3587). The present study illustrates the negative correlation between keratocyte apoptosis and corneal antioxidant enzyme activities. This finding suggests that ROS may be partly responsible for keratocyte apoptosis after refractive surgery.

  8. Evaluation of corneal higher order aberrations in normal topographic patterns

    Directory of Open Access Journals (Sweden)

    Ali Mirzajani

    2016-06-01

    Conclusions: Based on results in this study, there were a good correlation between corneal topographic pattern and corneal HOAs in normal eyes. These results indicate that the corneal HOAs values are largely determined by the topographic patterns. A larger sample size would perhaps have been beneficial to yield in more accurate outcomes.

  9. Clinical Validation of Point-Source Corneal Topography in Keratoplasty

    NARCIS (Netherlands)

    Vrijling, A C L; Braaf, B.; Snellenburg, J.J.; de Lange, F.; Zaal, M.J.W.; van der Heijde, G.L.; Sicam, V.A.D.P.

    2011-01-01

    Purpose. To validate the clinical performance of point-source corneal topography (PCT) in postpenetrating keratoplasty (PKP) eyes and to compare it with conventional Placido-based topography. Methods. Corneal elevation maps of the anterior corneal surface were obtained from 20 post-PKP corneas using

  10. Corneal surface temperature change as the mode of stimulation of the non-contact corneal aesthesiometer.

    Science.gov (United States)

    Murphy, P J; Morgan, P B; Patel, S; Marshall, J

    1999-05-01

    The non-contact corneal aesthesiometer (NCCA) assesses corneal sensitivity by using a controlled pulse of air, directed at the corneal surface. The purpose of this paper was to investigate whether corneal surface temperature change was a component in the mode of stimulation. Thermocouple experiment: A simple model corneal surface was developed that was composed of a moistened circle of filter paper placed on a thermocouple and mounted on a glass slide. The temperature change produced by different stimulus pressures was measured for five different ambient temperatures. Thermal camera experiment: Using a thermal camera, the corneal surface temperature change was measured in nine young, healthy subjects after exposure to different stimulus air pulses. Pulse duration was set at 0.9 s but was varied in pressure from 0.5 to 3.5 millibars. Thermocouple experiment: An immediate drop in temperature was detected by the thermocouple as soon as the air flow was incident on the filter paper. A greater temperature change was produced by increasing the pressure of the incident air flow. A relationship was found and a calibration curve plotted. Thermal camera experiment: For each subject, a drop in surface temperature was detected at each stimulus pressure. Furthermore, as the stimulus pressure increased, the induced reduction in temperature also increased. A relationship was found and a calibration curve plotted. The NCCA air-pulse stimulus was capable of producing a localized temperature change on the corneal surface. The principal mode of corneal nerve stimulation, by the NCCA air pulse, was the rate of temperature change of the corneal surface.

  11. Enhanced detection method for corneal protein identification using shotgun proteomics

    Directory of Open Access Journals (Sweden)

    Schlager John J

    2009-06-01

    Full Text Available Abstract Background The cornea is a specialized transparent connective tissue responsible for the majority of light refraction and image focus for the retina. There are three main layers of the cornea: the epithelium that is exposed and acts as a protective barrier for the eye, the center stroma consisting of parallel collagen fibrils that refract light, and the endothelium that is responsible for hydration of the cornea from the aqueous humor. Normal cornea is an immunologically privileged tissue devoid of blood vessels, but injury can produce a loss of these conditions causing invasion of other processes that degrade the homeostatic properties resulting in a decrease in the amount of light refracted onto the retina. Determining a measure and drift of phenotypic cornea state from normal to an injured or diseased state requires knowledge of the existing protein signature within the tissue. In the study of corneal proteins, proteomics procedures have typically involved the pulverization of the entire cornea prior to analysis. Separation of the epithelium and endothelium from the core stroma and performing separate shotgun proteomics using liquid chromatography/mass spectrometry results in identification of many more proteins than previously employed methods using complete pulverized cornea. Results Rabbit corneas were purchased, the epithelium and endothelium regions were removed, proteins processed and separately analyzed using liquid chromatography/mass spectrometry. Proteins identified from separate layers were compared against results from complete corneal samples. Protein digests were separated using a six hour liquid chromatographic gradient and ion-trap mass spectrometry used for detection of eluted peptide fractions. The SEQUEST database search results were filtered to allow only proteins with match probabilities of equal or better than 10-3 and peptides with a probability of 10-2 or less with at least two unique peptides isolated within

  12. PHAGOCYTOSIS AND REMODELING OF COLLAGEN MATRICES

    OpenAIRE

    Abraham, Leah C.; Dice, J Fred.; Lee, Kyongbum; Kaplan, David L.

    2007-01-01

    The biodegradation of collagen and the deposition of new collagen-based extracellular matrices are of central importance in tissue remodeling and function. Similarly, for collagen-based biomaterials used in tissue engineering, the degradation of collagen scaffolds with accompanying cellular infiltration and generation of new extracellular matrix is critical for integration of in vitro grown tissues in vivo. In earlier studies we observed significant impact of collagen structure on primary lun...

  13. Mechanisms of allograft rejection of corneal endothelium

    International Nuclear Information System (INIS)

    Tagawa, Y.; Silverstein, A.M.; Prendergast, R.A.

    1982-01-01

    The local intraocular graft-vs.-host (GVH) reaction, involving the destruction of the corneal endothelial cells of the rabbit host by sensitized donor lymphoid cells, has been used to study the mechanism of corneal allograft rejection. Pretreatment of donor cells with a specific mouse monoclonal hybridoma anti-T cell antibody and complement suppresses the destructive reaction, suggesting that a cellular-immune mechanism is primarily involved. Pretreatment of donor cells with mitomycin-C completely abolishes the local GVH reaction, indicating that the effector lymphocytes must undergo mitosis within the eye before they can engage in target cell destruction. Finally, studies of the local GVH reaction in irradiated leukopenic recipients or in preinflamed rabbit eyes suggest that host leukocytes may contribute nonspecifically to enhance the destructive process. These studies show that the local ocular GVH reaction may provide a useful model for the study of the mechanisms involved in the rejection of corneal allografts

  14. Dextran Preserves Native Corneal Structure During Decellularization.

    Science.gov (United States)

    Lynch, Amy P; Wilson, Samantha L; Ahearne, Mark

    2016-06-01

    Corneal decellularization has become an increasingly popular technique for generating scaffolds for corneal regeneration. Most decellularization procedures result in tissue swelling, thus limiting their application. Here, the use of a polysaccharide, dextran, to reduce swelling and conserve the native corneal structure during decellularization was investigated. Corneas were treated with 1% Triton X-100, 0.5% sodium dodecyl sulfate, and nucleases under constant rotation followed by extensive washing. To reduce swelling, decellularization solutions were supplemented with 5% dextran either throughout the whole decellularization process or during the washing cycles only. Quantitative analysis of DNA content showed a 96% reduction after decellularization regardless of the addition of dextran. Dextran resulted in a significant reduction in swelling from 3.85 ± 0.43 nm without to 1.94 ± 0.29-2.01 ± 0.37 nm (p dextran must be present throughout the decellularization protocol to preserve the native corneal architecture, anisotropy analysis demonstrated comparable results (0.22 ± 0.03) to the native cornea (0.24 ± 0.02), p > 0.05. Dextran can counteract the detrimental effects of decellularizing agents on the biomechanical properties of the tissue resulting in similar compressive moduli (mean before decellularization: 5.40 ± 1.18 kPa; mean after decellularization with dextran: 5.64 ± 1.34 kPa, p > 0.05). Cells remained viable in the presence of decellularized scaffolds. The findings of this study indicate that dextran not only prevents significant corneal swelling during decellularization but also enhances the maintenance of the native corneal ultrastructure.

  15. Host immune cellular reactions in corneal neovascularization

    Directory of Open Access Journals (Sweden)

    Nizar S. Abdelfattah

    2016-04-01

    Full Text Available Corneal neovascularization (CNV is a global important cause of visual impairment. The immune mechanisms leading to corneal heme- and lymphangiogenesis have been extensively studied over the past years as more attempts were made to develop better prophylactic and therapeutic measures. This article aims to discuss immune cells of particular relevance to CNV, with a focus on macrophages, Th17 cells, dendritic cells and the underlying immunology of common pathologies involving neovascularization of the cornea. Hopefully, a thorough understanding of these topics would propel the efforts to halt the detrimental effects of CNV.

  16. Research on inhibition of corneal neovascularization

    Directory of Open Access Journals (Sweden)

    Zhang-Hui Yang

    2015-12-01

    Full Text Available Corneal transparency is the basis of the normal physiological functions.However, corneal neovascularization(CNVmay occur in the infection, mechanical and chemical injury or under other pathological conditions,which make the cornea lose original transparency and severe visual impairment. In recent years, along with the development of immunology, molecular biology, biochemistry and other disciplines, there is more in-depth understanding on the CNV, and clinical treatment of CNV has made new breakthroughs. This article provides an overview of the inhibition of CNV.

  17. Resliced image space construction for coronary artery collagen fibers.

    Science.gov (United States)

    Luo, Tong; Chen, Huan; Kassab, Ghassan S

    2017-01-01

    Collagen fibers play an important role in the biomechanics of the blood vessel wall. The objective of this study was to determine the 3D microstructure of collagen fibers in the media and adventitia of coronary arteries. We present a novel optimal angle consistence algorithm to reform image slices in the visualization and analysis of 3D collagen images. 3D geometry was reconstructed from resliced image space where the 3D skeleton was extracted as the primary feature for accurate reconstruction of geometrical parameters. Collagen fibers (range 80-200) were reconstructed from the porcine coronary artery wall for the measurement of various morphological parameters. Collagen waviness and diameters were 1.37 ± 0.19 and 2.61 ± 0.89 μm, respectively. The biaxial distributions of orientation had two different peaks at 110.7 ± 25.2° and 18.4 ± 19.3°. Results for width, waviness, and orientation were found to be in good agreement with manual measurements. In addition to accurately measuring 2D features more efficiently than the manual approach, the present method produced 3D features that could not be measured in the 2D manual approach. These additional parameters included the tilt angle (5.10 ± 2.95°) and cross-sectional area (CSA; 5.98 ± 3.79 μm2) of collagen fibers. These 3D collagen reconstructions provide accurate and reliable microstructure for biomechanical modeling of vessel wall mechanics.

  18. Inelastic behaviour of collagen networks in cell–matrix interactions and mechanosensation

    Science.gov (United States)

    Mohammadi, Hamid; Arora, Pamma D.; Simmons, Craig A.; Janmey, Paul A.; McCulloch, Christopher A.

    2015-01-01

    The mechanical properties of extracellular matrix proteins strongly influence cell-induced tension in the matrix, which in turn influences cell function. Despite progress on the impact of elastic behaviour of matrix proteins on cell–matrix interactions, little is known about the influence of inelastic behaviour, especially at the large and slow deformations that characterize cell-induced matrix remodelling. We found that collagen matrices exhibit deformation rate-dependent behaviour, which leads to a transition from pronounced elastic behaviour at fast deformations to substantially inelastic behaviour at slow deformations (1 μm min−1, similar to cell-mediated deformation). With slow deformations, the inelastic behaviour of floating gels was sensitive to collagen concentration, whereas attached gels exhibited similar inelastic behaviour independent of collagen concentration. The presence of an underlying rigid support had a similar effect on cell–matrix interactions: cell-induced deformation and remodelling were similar on 1 or 3 mg ml−1 attached collagen gels while deformations were two- to fourfold smaller in floating gels of high compared with low collagen concentration. In cross-linked collagen matrices, which did not exhibit inelastic behaviour, cells did not respond to the presence of the underlying rigid foundation. These data indicate that at the slow rates of collagen compaction generated by fibroblasts, the inelastic responses of collagen gels, which are influenced by collagen concentration and the presence of an underlying rigid foundation, are important determinants of cell–matrix interactions and mechanosensation. PMID:25392399

  19. Mycobacterial laminin-binding histone-like protein mediates collagen-dependent cytoadherence

    Directory of Open Access Journals (Sweden)

    André Alves Dias

    2012-12-01

    Full Text Available When grown in the presence of exogenous collagen I, Mycobacterium bovis BCG was shown to form clumps. Scanning electron microscopy examination of these clumps revealed the presence of collagen fibres cross-linking the bacilli. Since collagen is a major constituent of the eukaryotic extracellular matrices, we assayed BCG cytoadherence in the presence of exogenous collagen I. Collagen increased the interaction of the bacilli with A549 type II pneumocytes or U937 macrophages, suggesting that BCG is able to recruit collagen to facilitate its attachment to host cells. Using an affinity chromatography approach, we have isolated a BCG collagen-binding protein corresponding to the previously described mycobacterial laminin-binding histone-like protein (LBP/Hlp, a highly conserved protein associated with the mycobacterial cell wall. Moreover, Mycobacterium leprae LBP/Hlp, a well-characterized adhesin, was also able to bind collagen I. Finally, using recombinant fragments of M. leprae LBP/Hlp, we mapped the collagen-binding activity within the C-terminal domain of the adhesin. Since this protein was already shown to be involved in the recognition of laminin and heparan sulphate-containing proteoglycans, the present observations reinforce the adhesive activities of LBP/Hlp, which can be therefore considered as a multifaceted mycobacterial adhesin, playing an important role in both leprosy and tuberculosis pathogenesis.

  20. Corneal hydrops induced by Bell’s paralysis in a case of corneal ectasia

    Directory of Open Access Journals (Sweden)

    Lokman Aslan

    2017-09-01

    Full Text Available An 18-year-old male patient presented with suddenly decreased vision, itching, corneal edema and an inability to close the left eye. They had left Bell’s paralysis for two weeks and had used high diopter glasses for five years. The best corrected visual acuity was 0.4 in their right eye and counting fingers in the left eye. Biomicroscopic examination revealed thinning and steepening of the cornea in the right eye and anterior protrusion of the cornea, stromal edema and punctate disruption of the epithelium in the left eye. Topographic image of the right eye was consistent with keratoconus. Six months later, stromal edema gradually regressed and a corneal scar ensued. This case presentation emphasizes that Bell’s palsy may induce disease progression in a patient with preexisting corneal ectasia and results in corneal hydrops. [Arch Clin Exp Surg 2017; 6(3.000: 165-167

  1. A new nanosecond UV laser at 355 nm: early results of corneal flap cutting in a rabbit model.

    Science.gov (United States)

    Trost, Andrea; Schrödl, Falk; Strohmaier, Clemens; Bogner, Barbara; Runge, Christian; Kaser-Eichberger, Alexandra; Krefft, Karolina; Vogel, Alfred; Linz, Norbert; Freidank, Sebastian; Hilpert, Andrea; Zimmermann, Inge; Grabner, Günther; Reitsamer, Herbert A

    2013-12-03

    A new 355 nm UV laser was used for corneal flap cutting in an animal model and tested for clinical and morphologic alterations. Corneal flaps were created (Chinchilla Bastards; n = 25) with an UV nanosecond laser at 355 nm (150 kHz, pulse duration 850 ps, spot-size 1 μm, spot spacing 6 × 6 μm, side cut Δz 1 μm; cutting depth 130 μm) and pulse energies of 2.2 or 2.5 μJ, respectively. Following slit-lamp examination, animals were killed at 6, 12, and 24 hours after treatment. Corneas were prepared for histology (hematoxylin and eosin [HE], TUNEL-assay) and evaluated statistically, followed by ultrastructural investigations. Laser treatment was tolerated well, flap lift was easier at 2.5 μJ compared with 2.2 μJ. Standard HE at 24 hours revealed intact epithelium in the horizontal cut, with similar increase in corneal thickness at both energies. Irrespective of energy levels, TUNEL assay revealed comparable numbers of apoptotic cells in the horizontal and vertical cut at 6, 12, and 24 hours, becoming detectable in the horizontal cut as an acellular stromal band at 24 hours. Ultrastructural analysis revealed regular morphology in the epi- and endothelium, while in the stroma, disorganized collagen lamellae were detectable representing the horizontal cut, again irrespective of energy levels applied. This new UV laser revealed no epi- nor endothelial damage at energies feasible for corneal flap cutting. Observed corneal swelling was lower compared with existing UV laser studies, albeit total energy applied here was much higher. Observed loss of stromal keratinocytes is comparable with available laser systems. Therefore, this new laser is suitable for refractive surgery, awaiting its test in a chronic environment.

  2. Biological effect of hydrolyzed collagen on bone metabolism.

    Science.gov (United States)

    Daneault, Audrey; Prawitt, Janne; Fabien Soulé, Véronique; Coxam, Véronique; Wittrant, Yohann

    2017-06-13

    Osteoporosis is a chronic and asymptomatic disease characterized by low bone mass and skeletal microarchitectural deterioration, increased risk of fracture, and associated comorbidities most prevalent in the elderly. Due to an increasingly aging population, osteoporosis has become a major health issue requiring innovative disease management. Proteins are important for bone by providing building blocks and by exerting specific regulatory function. This is why adequate protein intake plays a considerable role in both bone development and bone maintenance. More specifically, since an increase in the overall metabolism of collagen can lead to severe dysfunctions and a more fragile bone matrix and because orally administered collagen can be digested in the gut, cross the intestinal barrier, enter the circulation, and become available for metabolic processes in the target tissues, one may speculate that a collagen-enriched diet provides benefits for the skeleton. Collagen-derived products such as gelatin or hydrolyzed collagen (HC) are well acknowledged for their safety from a nutritional point of view; however, what is their impact on bone biology? In this manuscript, we critically review the evidence from literature for an effect of HC on bone tissues in order to determine whether HC may represent a relevant alternative in the design of future nutritional approaches to manage osteoporosis prevention.

  3. Corneal clarity measurements in healthy volunteers across different age groups: Observational study.

    Science.gov (United States)

    Alzahrani, Khaled; Carley, Fiona; Brahma, Arun; Morley, Debbie; Hillarby, M Chantal

    2017-11-01

    The aim of this study was to standardize and investigate the changes in corneal clarity with age. Densitometry software for the Oculus Pentacam was used to examine corneal clarity at different age groups.A total of 192 eyes from 97 healthy participants were included in this cohort comparative nonrandomized, cross-sectional study. An Oculus Pentcam was used to image the cornea of healthy participants grouped by age (between 10 and 70 years old). Data from the densitometry output have been used to determine clarity in concentric zones and different depths of the cornea.Corneal densitometry (CD) across all ages showed significant differences between groups when divided into the following layers: anterior, central, and posterior or divided into 0 to 2, 2 to 6, and 6 to 10 mm concentric zones (P age in all 3 layers of the periphery (6-10 mm) (P age group had lower clarity than the 20 to 30-age group (P age is differed when the cornea is divided into layers and zones. This study suggests that there are other factors that may play an essential role in corneal clarity as well as age.

  4. Corneal Aberrations in Former Preterm Infants: Results From The Wiesbaden Prematurity Study.

    Science.gov (United States)

    Fieß, Achim; Schuster, Alexander K; Kölb-Keerl, Ruth; Knuf, Markus; Kirchhof, Bernd; Muether, Philipp S; Bauer, Jacqueline

    2017-12-01

    To compare corneal aberrations in former preterm infants to that of full-term infants. A prospective cross-sectional study was carried out measuring the corneal shape with Scheimpflug imaging in former preterm infants of gestational age (GA) ≤32 weeks and full-term infants with GA ≥37 weeks now being aged between 4 to 10 years. The main outcome measures were corneal aberrations including astigmatism (Zernike: Z2-2; Z22), coma (Z3-1; Z31), trefoil (Z3-3; Z33), spherical aberration (Z40) and root-mean square of higher-order aberrations (RMS HOA). Multivariable analysis was performed to assess independent associations of gestational age groups and of retinopathy of prematurity (ROP) occurrence with corneal aberrations adjusting for sex and age at examination. A total of 259 former full-term and 226 preterm infants with a mean age of 7.2 ± 2.0 years were included in this study. Statistical analysis revealed an association of extreme prematurity (GA ≤28 weeks) with higher-order and lower-order aberrations of the total cornea. Vertical coma was higher in extreme prematurity (P prematurity rather than with ROP occurrence.

  5. Characteristics of, prevalence of, and risk factors for corneal pigmentation (pigmentary keratopathy) in Pugs.

    Science.gov (United States)

    Labelle, Amber L; Dresser, Christine B; Hamor, Ralph E; Allender, Matthew C; Disney, Julia L

    2013-09-01

    To determine the characteristics of, prevalence of, and risk factors for corneal pigmentation (CP) in Pugs. Prospective cross-sectional study. 295 Pugs > 16 weeks old. Ophthalmic examination of the anterior segment of each eye was performed, including determination of tear film characteristics (Schirmer tear test and tear film breakup time) and corneal sensitivity. Digital photographs of the head and each eye were obtained. Corneal pigmentation of eyes was graded as absent, very mild, mild, moderate, or severe. Signalment and medical history information and American Kennel Club registration status were recorded. Results-CP was detected in at least 1 eye of 243 of the 295 (82.4%) Pugs; CP was typically very mild or mild. Detection of CP was not significantly associated with coat color, age, eyelid conformation, or tear film characteristics but was significantly associated with sex of dogs. The severity of CP was not significantly associated with American Kennel Club registration status or age, but was significantly associated with sex, tear film characteristics, and coat color. Iris hypoplasia was detected in 72.1% of the Pugs. Iris-to-iris persistent pupillary membranes were detected in 85.3% of the Pugs. Prevalence of CP in Pugs in this study was high. Unexpectedly high prevalences of iris hypoplasia and persistent pupillary membranes were also identified. The condition identified in these Pugs was a pigmentary keratopathy, rather than pigmentary keratitis or corneal melanosis. This condition may have a genetic basis, and further studies are warranted to determine etiology.

  6. Enhanced stabilization of collagen by furfural.

    Science.gov (United States)

    Lakra, Rachita; Kiran, Manikantan Syamala; Usha, Ramamoorthy; Mohan, Ranganathan; Sundaresan, Raja; Korrapati, Purna Sai

    2014-04-01

    Furfural (2-furancarboxaldehyde), a product derived from plant pentosans, has been investigated for its interaction with collagen. Introduction of furfural during fibril formation enhanced the thermal and mechanical stability of collagen. Collagen films treated with furfural exhibited higher denaturation temperature (Td) (pFurfural and furfural treated collagen films did not have any cytotoxic effect. Rheological characterization showed an increase in shear stress and shear viscosity with increasing shear rate for treated collagen. Circular dichroism (CD) studies indicated that the furfural did not have any impact on triple helical structure of collagen. Scanning electron microscopy (SEM) of furfural treated collagen exhibited small sized porous structure in comparison with untreated collagen. Thus this study provides an alternate ecologically safe crosslinking agent for improving the stability of collagen for biomedical and industrial applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. A comparison study of Riboflavin/UV-A and Rose-Bengal/Green light cross-linking of the rabbit corneas using optical coherence elastography

    Science.gov (United States)

    Li, Jiasong; Singh, Manmohan; Han, Zhaolong; Vantipalli, Srilatha; Liu, Chih-Hao; Wu, Chen; Raghunathan, Raksha; Kazemi, Tina; Twa, Michael D.; Larin, Kirill V.

    2016-03-01

    The biomechanical properties of the cornea are critical factors which determine its health and subsequent visual acuity. Keratoconus is a structural degeneration of the cornea which can diminish vision quality. Riboflavin/UV-A corneal collagen cross-linking (UV-CXL) is an emerging treatment that increases the stiffness of the cornea and improves its ability to resist further degeneration. While UV-CXL has shown great promise for effective therapy of the keratoconus, there are concerns associated with the UV irradiation, such as keratocyte cytotoxicity. Rose-bengal/green light corneal collagen cross-linking (RGX) has been proposed as an alternative to UV-CXL. Because of the high absorbance of the rose-bengal dye at green wavelengths, the treatment time is significantly shorter than with UV-CXL. Moreover, because green light is used in lieu of UV irradiation, there are no cytotoxic side-effects. In this study, noncontact optical coherence elastography (OCE) was used to compare the outcomes of UV-CXL and RGX treatment in rabbit cornea. Low-amplitude (micrometer scale) elastic waves were induced by a focused air-pulse loading system. The elastic wave propagation was then imaged by a phase-stabilized swept source OCE (PhS-SSOCE) system. The changes in the viscoelasticity of the corneas were quantified by a previously developed modified Rayleigh Lamb frequency model. The depth-resolved micro-scale phase-velocity distribution in the cornea was used to reveal the depth-wise heterogeneity before and after both cross-linking techniques. Our results show that UV-CXL and RGX increased the stiffness of the corneas by ~54% and ~5% while reducing the viscosity by ~42% and ~17%, respectively. The depth-wise phase velocities showed that UV-CXL affected the anterior ~1/3 of the corneas, while RGX only affected the anterior ~1/7 of the corneas.

  8. Rate of Corneal Collagen Crosslinking Redo in Private Practice: Risk Factors and Safety

    Directory of Open Access Journals (Sweden)

    Joelle Antoun

    2015-01-01

    Full Text Available Objective. To report the rate of progression of keratectasia after primary crosslinking (CXL and evaluate the safety and efficiency of CXL redo. Materials and Methods. We conducted a retrospective analysis of the patients who underwent CXL between 2010 and 2013 at the Beirut Eye Specialist Hospital, Lebanon. Progression of keratectasia was based on the presence of an increase in maximum keratometry of 1.00 D, a change in the map difference between two consecutive topographies of 1.00 D, a deterioration of visual acuity, or any change in the refraction. Primary and redo CXL were done using the same protocol. Results. Among the 221 eyes of 130 patients who underwent CXL, 7 eyes (3.17% of five patients met the criteria of progression. All patients reported a history of allergic conjunctivitis and eye rubbing and progressed within 9 to 48 months. No complications were noted and all patients were stable 1 year after CXL redo. Conclusion. Allergic conjunctivitis and eye rubbing were the only risk factors associated with keratoconus progression after CXL. A close followup is thus mandatory, even years after the procedure. CXL redo seems to be a safe and efficient technique to halt the progression after a primary CXL.

  9. Longitudinal changes in corneal curvature and its relationship to axial length in the Correction of Myopia Evaluation Trial (COMET cohort

    Directory of Open Access Journals (Sweden)

    Mitchell Scheiman

    2016-01-01

    Conclusions: Differences in average corneal curvature by age, gender, and ethnicity observed in early childhood remain consistent as myopia progresses and stabilizes. This study also demonstrates increases in the AL/CR ratio as myopia progresses and then stabilizes, supporting observations from previous cross-sectional data.

  10. Polysaccharide coating of human corneal endothelium

    DEFF Research Database (Denmark)

    Schroder, H D; Sperling, S

    1977-01-01

    Electron microscopy revealed the presence of a 600-1500 A thick layer of polysaccharide on the surface of human corneal endothelial cells. The surface layer was visualized by combined fixation and staining in a mixture of ruthenium red and osmium tetroxide. The coating material was stable for at ...... for at least 39 h post mortem and was retained on disintegrating cells....

  11. Ultraviolet induced lysosome activity in corneal epithelium

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, A.P.

    1980-01-01

    A 5.000 W Xe-Hg high pressure lamp and a double monochromator were used to produce a 3.3 nm half-bandpass ultraviolet radiation at 295 nm. Pigmented rabbit eyes were irradiated with radiant exposures from 140 Jm/sup -2/ to 10.000 Jm/sup -2/ and evaluated by slit-lamp biomicroscopy, light and electron microscopy. Corneal threshold (Hsub(c) was 200 Jm/sup -2/ and lens threshold (Hsub(L)) was 7.500 Jm/sup -2/. The most repeatable and reliable corneal response to these levels of UV was the development of corneal epithelial granules. Histological changes included a loss of superficial epithelial cells and selective UV induced autolysis of the wing cells. It is suggested that the biomicroscopically observed granules are the clinical manifestation of the secondary lysosomes revealed by light and electron microscopy. It is proposed that UV breaks down the primary lysosome membranes to release hydrolytic enzymes which in turn form the secondary lysosomes during autolysis. Extreme levels of radiant exposure at 295 nm result in indiscriminate destruction of all layers of the corneal epithelium, but the posterior cornea was spared.

  12. Ultraviolet induced lysosome activity in corneal epithelium

    International Nuclear Information System (INIS)

    Cullen, A.P.

    1980-01-01

    A 5.000 W Xe-Hg high pressure lamp and a double monochromator were used to produce a 3.3 nm half-bandpass ultraviolet radiation at 295 nm. Pigmented rabbit eyes were irradiated with radiant exposures from 140 Jm -2 to 10.000 Jm -2 and evaluated by slit-lamp biomicroscopy, light and electron microscopy. Corneal threshold (Hsub(c) was 200 Jm -2 and lens threshold (Hsub(L)) was 7.500 Jm -2 . The most repeatable and reliable corneal response to these levels of UV was the development of corneal epithelial granules. Histological changes included a loss of superficial epithelial cells and selective UV induced autolysis of the wing cells. It is suggested that the biomicroscopically observed granules are the clinical manifestation of the secondary lysosomes revealed by light and electron microscopy. It is proposed that UV breaks down the primary lysosome membranes to release hydrolytic enzymes which in turn form the secondary lysosomes during autolysis. Extreme levels of radiant exposure at 295 nm result in indiscriminate destruction of all layers of the corneal epithelium, but the posterior cornea was spared. (orig.) [de

  13. Corneal ulcers: For the general practitioner

    African Journals Online (AJOL)

    Speci c enquiry as to instillation of medication (e.g. steroid drops) or home ... unaided and then with pinhole, with the fellow eye occluded. As a corneal ... topical anaesthetic drops will assist in making the patient comfortable enough to open ...

  14. Past and present of corneal refractive surgery

    DEFF Research Database (Denmark)

    Vestergaard, Anders Højslet

    Surgical correction of refractive errors is becoming increasingly popular. In the 1990s, the excimer laser revolutionized the field of corneal refractive surgery with PRK and LASIK, and lately refractive lenticule extraction (ReLEx) of intracorneal tissue, using only a femtosecond laser, has become...

  15. Management of Corneal Bee Sting Injuries.

    Science.gov (United States)

    Rai, Ruju R; Gonzalez-Gonzalez, Luis A; Papakostas, Thanos D; Siracuse-Lee, Donna; Dunphy, Robert; Fanciullo, Lisa; Cakiner-Egilmez, Tulay; Daly, Mary K

    2017-01-01

    To review the management of keratitis after corneal bee stings and to report a case of deep stromal corneal infiltrate secondary to a retained bee stinger managed conservatively in a patient who presented three days after unsanitary manipulation of the stinger apparatus. Case report and review of literature. A 57-year-old male beekeeper was evaluated for pain, blurry vision, and photosensitivity after a corneal bee sting. Of note, the venom sac had been removed with dirty tweezers three days prior to his visit. On exam, a focal infiltrate with diffuse edema was seen surrounding a retained bee stinger in the peripheral cornea. Trace cells in the anterior chamber were also noted. Based on a high suspicion for infectious keratitis, a conservative treatment strategy was elected. Administration of broad-spectrum topical antibiotics with concomitant abstention of corticosteroids led to rapid resolution of the symptoms. Over 16 months of follow-up, the stinger has remained in situ without migration and the patient has maintained 20/20 visual acuity without complications. There is debate on the preferred method for the management of corneal injury secondary to bee stings, especially when it is associated with a retained stinger. We herein present our findings in our appraisal of reported cases. In the aftermath of an ocular bee sting, close surveillance for inflammation and infection is essential. Individual manifestations of these injuries vary in timing, type, and severity; therefore, the accessibility of the stinger and the evolving clinical picture should guide therapeutic decisions.

  16. 21 CFR 886.1220 - Corneal electrode.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Corneal electrode. 886.1220 Section 886.1220 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... to the cornea to provide data showing the changes in electrical potential in the retina after...

  17. Corneal topography measurements for biometric applications

    Science.gov (United States)

    Lewis, Nathan D.

    The term biometrics is used to describe the process of analyzing biological and behavioral traits that are unique to an individual in order to confirm or determine his or her identity. Many biometric modalities are currently being researched and implemented including, fingerprints, hand and facial geometry, iris recognition, vein structure recognition, gait, voice recognition, etc... This project explores the possibility of using corneal topography measurements as a trait for biometric identification. Two new corneal topographers were developed for this study. The first was designed to function as an operator-free device that will allow a user to approach the device and have his or her corneal topography measured. Human subject topography data were collected with this device and compared to measurements made with the commercially available Keratron Piccolo topographer (Optikon, Rome, Italy). A third topographer that departs from the standard Placido disk technology allows for arbitrary pattern illumination through the use of LCD monitors. This topographer was built and tested to be used in future research studies. Topography data was collected from 59 subjects and modeled using Zernike polynomials, which provide for a simple method of compressing topography data and comparing one topographical measurement with a database for biometric identification. The data were analyzed to determine the biometric error rates associated with corneal topography measurements. Reasonably accurate results, between three to eight percent simultaneous false match and false non-match rates, were achieved.

  18. Research on mouse model of grade II corneal alkali burn

    Directory of Open Access Journals (Sweden)

    Jun-Qiang Bai

    2016-04-01

    Full Text Available AIM: To choose appropriate concentration of sodium hydroxide (NaOH solution to establish a stable and consistent corneal alkali burn mouse model in grade II. METHODS: The mice (n=60 were randomly divided into four groups and 15 mice each group. Corneal alkali burns were induced by placing circle filter paper soaked with NaOH solutions on the right central cornea for 30s. The concentrations of NaOH solutions of groups A, B, C, and D were 0.1 mol/L, 0.15 mol/L , 0.2 mol/L, and 1.0 mol/L respectively. Then these corneas were irrigated with 20 mL physiological saline (0.9% NaCl. On day 7 postburn, slit lamp microscope was used to observe corneal opacity, corneal epithelial sodium fluorescein staining positive rate, incidence of corneal ulcer and corneal neovascularization, meanwhile pictures of the anterior eyes were taken. Cirrus spectral domain optical coherence tomography was used to scan cornea to observe corneal epithelial defect and corneal ulcer. RESULTS: Corneal opacity scores ( were not significantly different between the group A and group B (P=0.097. Incidence of corneal ulcer in group B was significantly higher than that in group A (P=0.035. Incidence of corneal ulcer and perforation rate in group B was lower than that in group C. Group C and D had corneal neovascularization, and incidence of corneal neovascularization in group D was significantly higher than that in group C (P=0.000. CONCLUSION: Using 0.15 mol/L NaOH can establish grade II mouse model of corneal alkali burns.

  19. Effects of artificial tear treatment on corneal epithelial thickness and corneal topography findings in dry eye patients.

    Science.gov (United States)

    Çakır, B; Doğan, E; Çelik, E; Babashli, T; Uçak, T; Alagöz, G

    2018-05-01

    To investigate the effects of artificial tear treatment on central corneal epithelial thickness, and central, mid-peripheral and peripheral corneal thicknesses in patients with dry eye disease (DED). Patients with DED underwent ocular examinations, including Schirmer-2 test, slit lamp examination for tear break-up time (BUT), corneal topography (CT) for measuring mean central, mid-peripheral and peripheral corneal thickness values and anterior segment optic coherence tomography (AS-OCT) for obtaining central corneal epithelial thickness. After artificial tear treatment (carboxymethylcellulose and sodium hyaluronate formulations) for one month, patients were examined again at a second visit and the results were compared. Sixty-one eyes of 33 female dry eye patients (mean age: 38.3±5.7 years) were enrolled. The mean follow-up time was 36.4±3.3 days. The mean tear BUT and Schirmer-1 tests revealed significant improvement after treatment (P=0.000, P=0.000, respectively). Central corneal epithelium and mean mid-peripheral corneal thicknesses measured significantly higher after treatment (P=0.001, P=0.02). Changes in central and peripheral corneal thicknesses were not statistically significant. Artificial tear treatment in dry eye patients seems to increase central corneal epithelial and mid-peripheral corneal thicknesses. Measurement of corneal epithelial thickness can be a useful tool for evaluation of treatment response in dry eye patients. Further long-term prospective studies are needed to investigate this item. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  20. Collagen and mineral deposition in rabbit cortical bone during maturation and growth: effects on tissue properties.

    Science.gov (United States)

    Isaksson, Hanna; Harjula, Terhi; Koistinen, Arto; Iivarinen, Jarkko; Seppänen, Kari; Arokoski, Jari P A; Brama, Pieter A; Jurvelin, Jukka S; Helminen, Heikki J

    2010-12-01

    We characterized the composition and mechanical properties of cortical bone during maturation and growth and in adult life in the rabbit. We hypothesized that the collagen network develops earlier than the mineralized matrix. Growth was monitored, and the rabbits were euthanized at birth (newborn), and at 1, 3, 6, 9, and 18 months of age. The collagen network was assessed biochemically (collagen content, enzymatic and non-enzymatic cross-links) in specimens from the mid-diaphysis of the tibia and femur and biomechanically (tensile testing) from decalcified whole tibia specimens. The mineralized matrix was analyzed using pQCT and 3-point bend tests from intact femur specimens. The collagen content and the Young's modulus of the collagen matrix increased significantly until the rabbits were 3 months old, and thereafter remained stable. The amount of HP and LP collagen cross-links increased continuously from newborn to 18 months of age, whereas PEN cross-links increased after 6 months of age. Bone mineral density and the Young's modulus of the mineralized bone increased until the rabbits were at least 6 months old. We concluded that substantial changes take place during the normal process of development in both the biochemical and biomechanical properties of rabbit cortical bone. In cortical bone, the collagen network reaches its mature composition and mechanical strength prior to the mineralized matrix. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  1. The Steroids for Corneal Ulcers Trial

    Science.gov (United States)

    Srinivasan, Muthiah; Mascarenhas, Jeena; Rajaraman, Revathi; Ravindran, Meenakshi; Lalitha, Prajna; Glidden, David V.; Ray, Kathryn J.; Hong, Kevin C.; Oldenburg, Catherine E.; Lee, Salena M.; Zegans, Michael E.; McLeod, Stephen D.; Lietman, Thomas M.; Acharya, Nisha R.

    2013-01-01

    Objectives To provide comprehensive trial methods and baseline data for the Steroids for Corneal Ulcers Trial and to present epidemiological characteristics such as risk factors, causative organisms, and ulcer severity. Methods Baseline data from a 1:1 randomized, placebo-controlled, double-masked clinical trial comparing prednisolone phosphate, 1%, with placebo as adjunctive therapy for the treatment of bacterial corneal ulcers. Eligible patients had a culture-positive bacterial corneal ulcer and had been taking moxifloxacin for 48 hours. The primary outcome for the trial is best spectacle-corrected visual acuity at 3 months from enrollment. This report provides comprehensive baseline data, including best spectacle-corrected visual acuity, infiltrate size, microbio-logical results, and patient demographics, for patients enrolled in the trial. Results Of 500 patients enrolled, 97% were in India. Two hundred twenty patients (44%) were agricultural workers. Median baseline visual acuity was 0.84 logMAR (Snellen, 20/125) (interquartile range, 0.36-1.7; Snellen, 20/50 to counting fingers). Baseline visual acuity was not significantly different between the United States and India. Ulcers in India had larger infiltrate/scar sizes (P=.04) and deeper infiltrates (P=.04) and were more likely to be localized centrally (P=.002) than ulcers enrolled in the United States. Gram-positive bacteria were the most common organisms isolated from the ulcers (n=366, 72%). Conclusions The Steroids for Corneal Ulcers Trial will compare the use of a topical corticosteroid with placebo as adjunctive therapy for bacterial corneal ulcers. Patients enrolled in this trial had diverse ulcer severity and on average significantly reduced visual acuity at presentation. PMID:21987581

  2. Development of a nanofiltration method for bone collagen {sup 14}C AMS dating

    Energy Technology Data Exchange (ETDEWEB)

    Boudin, Mathieu, E-mail: mathieu.boudin@ugent.be [Royal Institute for Cultural Heritage, Jubelpark 1, B-1000 Brussels (Belgium); Ghent University, Faculty of Bioscience Engineering, Laboratory of Applied Physical Chemistry, Coupure Links 653, B-9000 Ghent (Belgium); Boeckx, Pascal [Ghent University, Faculty of Bioscience Engineering, Laboratory of Applied Physical Chemistry, Coupure Links 653, B-9000 Ghent (Belgium); Buekenhoudt, Anita [Flemish Institute for Technological Research, Separation and Conversion Technology, Boeretang 200, B-2400 Mol (Belgium); Vandenabeele, Peter [Ghent University, Department of Archaeology, Sint-Pietersnieuwstraat 35, B-9000 Ghent (Belgium); Van Strydonck, Mark [Royal Institute for Cultural Heritage, Jubelpark 1, B-1000 Brussels (Belgium)

    2013-01-15

    Radiocarbon dating of bones is usually performed on the collagen fraction. However, this collagen can contain exogenous molecules, including humic substances (HSs) and/or other soil components that may have a different age than the bone. Incomplete removal can result in biased {sup 14}C dates. Ultrafiltration of collagen, dissolved as gelatin (molecular weight (MW) {approx}100,000 Dalton), has received considerable attention to obtain more reliable dates. Ultrafiltration is an effective method of removal of low-molecular weight contaminants from bone collagen but it does not remove high-molecular weight contaminants, such as cross-linked humic collagen complexes. However, comparative dating studies have raised the question whether this cleaning step itself may introduce contamination with carbon from the filters used. In this study, a nanofiltration method was developed using a ceramic filter to avoid a possible extraneous carbon contamination introduced by the filter. This method should be applicable to various protein materials e.g. collagen, silk, wool, leather and should be able to remove low-molecular and high molecular weight HSs. In this study bone collagen was hot acid hydrolyzed to amino acids and nanofiltrated. A filter with a molecular weight cutoff (MWCO) of 450 Dalton was chosen in order to collect the amino acids in the permeate and the HSs in the retentate. Two pilot studies were set up. Two nanofiltration types were tested in pilot study 1: dead end and cross flow filtration. Humic substance (HS)-solutions with fossil carbon and modern hydrolyzed collagen contaminated with HSs were filtrated and analyzed with spectrofluorescence to determine the HS removal. Cross flow nanofiltration showed the most efficient HS removal. A second pilot study based upon these results was set up wherein only cross flow filtration was performed. {sup 14}C measurements of the permeates of hydrolyzed modern collagen contaminated with fossil HSs demonstrate a significant

  3. Ocular lens availability of glutathione from collagen inserts for protection of eye from radiation

    International Nuclear Information System (INIS)

    Omer, S.A.

    2003-01-01

    Full text: Ocular inserts of glutathione ( G ) were prepared using 1 % collagen solution containing free G ,liposomal G and liposomal G with Concanavalin A ,a specific targeting agent of G to ocular lens. These inserts have to be sterilized for in-vivo ophthalmic application by exposure to U V radiation for 2 hr. using dry ice and acetone for protection of G from thermal degradation. In vitro release characteristics of G (17.0 μ mole) from the prepared inserts were investigated at 37deg C in phosphate buffer pH 7.4 . The results of release data showed that the release of G from inserts were arranged in the following order, free G, liposomal G with or without Concanavalin A. The extent of uptake of G from the collagen inserts by rabbit cornea was also tested. The results of ocular lens availability of G from collagen inserts revealed that a highly significant increase in the uptake of G by ocular lenses,where the percentages drug uptake from the applied doses at T max were 1.12% (p(0.05), 2.12% (p(0.01) and 3.4% (p(0.001) in case of using collagen inserts containing free G, liposomal G and liposomal G with Concanavalin A respectively. That is to say,lipid nature of liposomes together with Concanavlin A improved the penetration of the entrapped hydrophilic G through corneal barrier to the ocular lenses

  4. Collagen like peptide bioconjugates for targeted drug delivery applications

    Science.gov (United States)

    Luo, Tianzhi

    Collagen is the most abundant protein in mammals, and there has been long-standing interest in understanding and controlling collagen assembly in the design of new materials. Collagen-like peptides (CLP), also known as collagen-mimetic peptides (CMP), are short synthetic peptides which mimic the triple helical conformation of native collagens. In the past few decades, collagen like peptides and their conjugated hybrids have become a new class of biomaterials that possesses unique structures and properties. In addition to traditional applications of using CLPs to decipher the role of different amino acid residues and tripeptide motifs in stabilizing the collagen triple helix and mimicking collagen fibril formation, with the introduction of specific interactions including electrostatic interactions, pi-pi stacking interaction and metal-ligand coordination, a variety of artificial collagen-like peptides with well-defined sequences have been designed to create higher order assemblies with specific biological functions. The CLPs have also been widely used as bioactive domains or physical cross-linkers to fabricate hydrogels, which have shown potential to improve cell adhesion, proliferation and ECM macromolecule production. Despite this widespread use, the utilization of CLPs as domains in stimuli responsive bioconjugates represents a relatively new area for the development of functional polymeric materials. In this work, a new class of thermoresponsive diblock conjugates, containing collagen-like peptides and a thermoresponsive polymer, namely poly(diethylene glycol methyl ether methacrylate) (PDEGMEMA), is introduced. The CLP domain maintains its triple helix conformation after conjugation with the polymer. The engineered LCST of these conjugates has enabled temperature-induced assembly under aqueous conditions, at physiologically relevant temperatures, into well-defined vesicles with diameters of approximately 50-200 nm. The formation of nanostructures was driven by

  5. Ethinyl oestradiol administration in women suppresses synthesis of collagen in tendon in response to exercise

    DEFF Research Database (Denmark)

    Hansen, Mette; Koskinen, Satu O; Petersen, Susanne G

    2008-01-01

    24 h post-exercise through microdialysis catheters placed anterior to the patellar tendon in both legs and subsequently analysed for the amino-terminal propeptide of type I collagen (PINP), a marker of tendon collagen synthesis. To determine the long-term effect of OC usage, patellar tendon cross......-OC 24 h post-exercise is consistent with the hypothesis that oestradiol inhibits exercise-induced collagen synthesis in human tendon. The mechanism behind this is either a direct effect of oestradiol, or an indirect effect via a reduction in levels of free IGF-I. However, the data did not indicate any......Women are at greater risk than men of sustaining certain kinds of injury and diseases of collagen-rich tissues. To determine whether a high level of oestradiol has an acute influence on collagen synthesis in tendons at rest and in response to exercise, one-legged kicking exercise was performed...

  6. Safety and efficacy of collagen crosslinking for the treatment of keratoconus.

    Science.gov (United States)

    Kolli, Sai; Aslanides, Ioannis M

    2010-11-01

    Keratoconus is a condition that causes corneal ectasia and reduced vision in young adults. A proportion of these patients have progressive disease requiring corneal transplantation. A revolutionary new treatment that is purported to halt progression of keratoconus, known as collagen crosslinking (CXL), has recently been introduced into clinical practice. CXL involves the treatment of the cornea with riboflavin followed by photoactivation with UVA light leading to corneal strengthening. This article reviews the basic science, clinical protocols, safety aspects and clinical results of CXL. The reader will gain a comprehensive understanding of: i) the basic science of CXL; ii) the optimised protocols for clinical use of CXL; iii) the results of all the main clinical trials in the literature; iv) contraindications to treatment and v) full clinical safety profile of CXL. CXL represents a new treatment that uniquely allows the halt of progression of keratoconus, thus preventing visual loss and the need for surgical intervention. Available data suggest that this treatment has high efficacy and is very safe and may represent the future standard treatment for progressive keratoconus.

  7. Quantitative assessment of rat corneal thickness and morphology during stem cell therapy by high-speed optical coherence tomography

    Science.gov (United States)

    Lal, Cerine; McGrath, James; Subhash, Hrebesh; Rani, Sweta; Ritter, Thomas; Leahy, Martin

    2016-03-01

    Optical Coherence Tomography (OCT) is a non-invasive 3 dimensional optical imaging modality that enables high resolution cross sectional imaging in biological tissues and materials. Its high axial and lateral resolution combined with high sensitivity, imaging depth and wide field of view makes it suitable for wide variety of high resolution medical imaging applications at clinically relevant speed. With the advent of swept source lasers, the imaging speed of OCT has increased considerably in recent years. OCT has been used in ophthalmology to study dynamic changes occurring in the cornea and iris, thereby providing physiological and pathological changes that occur within the anterior segment structures such as in glaucoma, during refractive surgery, lamellar keratoplasty and corneal diseases. In this study, we assess the changes in corneal thickness in the anterior segment of the eye during wound healing process in a rat corneal burn model following stem cell therapy using high speed swept source OCT.

  8. Sorption of sodium hydroxide by type I collagen and bovine corneas.

    Science.gov (United States)

    Whikehart, D R; Edwards, W C; Pfister, R R

    1991-01-01

    There are no quantitative studies on the uptake of alkali into corneal tissues. To study this phenomenon, both type I collagen and bovine corneas were incubated in sodium hydroxide (NaOH) under varying conditions for periods up to 27.5 h. The sorption (absorption or adsorption) of the alkali to protein and tissue was measured as the quantity of NaOH no longer available for titration to neutrality with hydrochloric acid. Sorption was found to be dependent on the concentration of NaOH (0.01-1 N) but independent of the incubation temperature (4-35 degrees C). In whole cornea, sorption of 1 N NaOH began immediately and increased with time up to 6 h. After 6 h, sorption decreased, together with the observed degradation and solubilization of the tissue. Stripping of the corneal endothelium alone or of the endothelium and epithelium increased sorption in a similar manner when compared to whole corneas for periods up to 4 h. These observations are compatible with ionic and nonionic bonding of hydroxide ions to collagen (including that of the cornea) and the subsequent release of hydroxide ions during hydrolysis of the protein itself. Indirect evidence also suggests the inclusion of quantities of unbound hydroxide ions in hydrated gels of glycosaminoglycans. It is proposed that in a chemical burn of the cornea, alkali is both stored in the tissue (by sorption) and reacted with it (by hydrolysis), without any net consumption of alkali taking place.

  9. Retinal nerve fiber layer measurements by scanning laser polarimetry with enhanced corneal compensation in healthy subjects.

    Science.gov (United States)

    Rao, Harsha L; Venkatesh, Chirravuri R; Vidyasagar, Kelli; Yadav, Ravi K; Addepalli, Uday K; Jude, Aarthi; Senthil, Sirisha; Garudadri, Chandra S

    2014-12-01

    To evaluate the (i) effects of biological (age and axial length) and instrument-related [typical scan score (TSS) and corneal birefringence] parameters on the retinal nerve fiber layer (RNFL) measurements and (ii) repeatability of RNFL measurements with the enhanced corneal compensation (ECC) protocol of scanning laser polarimetry (SLP) in healthy subjects. In a cross-sectional study, 140 eyes of 73 healthy subjects underwent RNFL imaging with the ECC protocol of SLP. Linear mixed modeling methods were used to evaluate the effects of age, axial length, TSS, and corneal birefringence on RNFL measurements. One randomly selected eye of 48 subjects from the cohort underwent 3 serial scans during the same session to determine the repeatability. Age significantly influenced all RNFL measurements. RNFL measurements decreased by 1 µm for every decade increase in age. TSS affected the overall average RNFL measurement (β=-0.62, P=0.003), whereas residual anterior segment retardance affected the superior quadrant measurement (β=1.14, P=0.01). Axial length and corneal birefringence measurements did not influence RNFL measurements. Repeatability, as assessed by the coefficient of variation, ranged between 1.7% for the overall average RNFL measurement and 11.4% for th nerve fiber indicator. Age significantly affected all RNFL measurements with the ECC protocol of SLP, whereas TSS and residual anterior segment retardance affected the overall average and the superior average RNFL measurements, respectively. Axial length and corneal birefringence measurements did not influence any RNFL measurements. RNFL measurements had good intrasession repeatability. These results are important while evaluating the change in structural measurements over time in glaucoma patients.

  10. Collagen crosslinks in chondromalacia of the patella.

    Science.gov (United States)

    Väätäinen, U; Kiviranta, I; Jaroma, H; Arokosi, J; Tammi, M; Kovanen, V

    1998-02-01

    The aim of the study was to determine collagen concentration and collagen crosslinks in cartilage samples from chondromalacia of the patella. To study the extracellular matrix alterations associated to chondromalacia, we determined the concentration of collagen (hydroxyproline) and its hydroxylysylpyridinoline and lysylpyridinoline crosslinks from chondromalacia foci of the patellae in 12 patients and 7 controls from apparently normal cadavers. The structure of the collagen network in 8 samples of grades II-IV chondromalacia was examined under polarized light microscopy. The full-thickness cartilage samples taken with a surgical knife from chondromalacia lesions did not show changes in collagen, hydroxylysylpyridinoline and lysylpyridinoline concentration as compared with the controls. Polarized light microscopy showed decreased birefringence in the superficial cartilage of chondromalacia lesions, indicating disorganization or disappearance of collagen fibers in this zone. It is concluded that the collagen network shows gradual disorganization with the severity of chondromalacia lesion of the patella without changes in the concentration or crosslinks of collagen.

  11. Ultrastructural Changes and Corneal Wound Healing After SMILE and PRK Procedures.

    Science.gov (United States)

    Wei, Shengsheng; Wang, Yan; Wu, Di; Zu, PeiPei; Zhang, Hui; Su, Xiaolian

    2016-10-01

    To compare keratocyte activation, cellular morphologic changes and wound healing after SMILE and PRK procedures using transmission electron microscope (TEM). In this study, 22 New Zealand white rabbits (10- to 15-week old) were used. The right eyes of all animals underwent SMILE procedure and the left eyes underwent PRK procedure. Cornea samples taken 1 day and 1 week postoperatively were examined using TEM. Using TEM 1 day after SMILE procedure, the organization of collagen fibers seemed to have been preserved without thermal alterations. Keratocyte activation was observed in the anterior stroma. Disrupted collagen arrangement and debris of cells are visible in the area of damage, and some phagocytic cells and a large number of secondary lysosomes are visible in those cells. At the perimeter zone of the interface, many coenocytes and collagen fragments could be found within the phagocytic cell. One week after SMILE procedure, potential lacuna could be discerned. A large part of the interface of the lenticule extracted had an appearance of clearly being adhered to some mucus secretions. One day after PRK procedure, an irregular epithelial surface was visible using TEM. Keratocytes had been activated and the rough endoplasmic reticulum in those cells had expanded. One week after PRK procedure, the epithelial surface still was irregular and keratinization of the epithelium was still visible in some areas. Corneal endothelium cells were mildly damaged and some vacuoles within the cytoplasm could be discerned. In the anterior stroma, some unhealthy activated keratocytes could still be observed. New collagen fibrils were found present near the activated keratocytes. Using TEM, keratocyte activation could still be observed after SMILE compared to after PRK procedure. Fewer cellular ultrastructural changes were seen after SMILE procedure. Unlike in PRK procedure, no damaged epithelium and endothelium were found after SMILE.

  12. Reinforcement of a porous collagen scaffold with surface-activated PLA fibers.

    Science.gov (United States)

    Liu, Xi; Huang, Changbin; Feng, Yujie; Liang, Jie; Fan, Yujiang; Gu, Zhongwei; Zhang, Xingdong

    2010-01-01

    A hybrid porous collagen scaffold mechanically reinforced with surface-activated poly(lactic acid) (PLA) fiber was prepared. PLA fibers, 20 mum in diameter and 1 mm in length, were aminolyzed with hexanediamine to introduce free amino groups on the surfaces. After the amino groups were transferred to aldehyde groups by treatment with glutaraldehyde, different amounts (1.5, 3, 5 and 8 mg) of surface-activated PLA fibers were homogeneously mixed with 2 ml type-I collagen solution (pH 2.8, 0.6 wt%). This mixture solution was then freeze-dried and cross-linked to obtain collagen sponges with surface-activated PLA fiber. Scanning electron microscopy observation indicated that the collagen sponges had a highly interconnected porous structure with an average pore size of 170 mum, irrespective of PLA fiber incorporation. The dispersion of surface-activated PLA fibers was homogeneous in collagen sponge, in contrast to unactivated PLA fibers. The compression modulus test results showed that, compared with unactivated PLA fibers, the surface-activated PLA fibers enhanced the resistance of collagen sponge to compression more significantly. Cytotoxicity assay by MTT test showed no cytotoxicity of these collagen sponges. L929 mouse fibroblast cell-culture studies in vitro revealed that the number of L929 cells attached to the collagen sponge with surface-activated PLA fibers, both 6 h and 24 h after seeding, was higher than that in pure collagen sponge and sponge with unactivated PLA fibers. In addition, a better distribution of cells infiltrated in collagen sponge with surface-activated PLA fibers was observed by histological staining. These results indicated that the collagen sponge reinforced with surface-activated PLA fibers is a promising biocompatible scaffold for tissue engineering.

  13. Unilateral corneal leukoplakia without limbal involvement

    Directory of Open Access Journals (Sweden)

    Hirano K

    2015-05-01

    Full Text Available Koji Hirano,1 Mihoko Koide,2 Yoshikazu Mizoguchi,3 Yasuhiro Osakabe,4 Kaoru-Araki Sasaki5 1Department of Ophthalmology, Ban Buntane Hotokukai Hospital, School of Medicine, Fujita Health University, Nagoya, Japan; 2Koide Internal Medicine and Eye Clinic, Nagoya, Japan; 3Department of Pathology, Ban Buntane Hotokukai Hospital, School of Medicine, Fujita Health University, Nagoya, Japan; 4Department of Molecular Pathology, Tokyo Medical University, Tokyo, Japan; 5Department of Ophthalmology, Japan Health Care Organization, Hoshigaoka Medical Center, Hirakata, Japan Purpose: Leukoplakia is the term given to a white patch or plaque that is found mainly on the oral mucus membrane. It can occasionally be seen on the corneal surface. We report our clinical and histopathological findings in a case of unilateral corneal leukoplakia. Methods: A 26-year-old woman was referred to our hospital because of a white patch on her right cornea that continued to expand. She first noticed the white patch when she was 20 years old, and the white patch had expanded to cover the pupillary area affecting her vision. After plastic surgery on both eyelids for bilateral entropion to alleviate the pain caused by the eyelashes rubbing the cornea, the white corneal patch decreased in size. Because of this reduction, we performed surgery to remove the patch with microforceps under topical anesthesia. The plaque was removed easily and completely, and submitted for histopathological examination. Results: Histopathological examination showed that the specimen had characteristics of epidermis with a basal cell layer, spinous cell layer, granular cell layer, and horny layer with hyperkeratosis. She was diagnosed with leukoplakia of the corneal surface. The basic structure of the squamous cell layer was preserved, and there were no signs of metaplasia. Six months after the removal of the leukoplakia, no recurrence was seen and her corrected decimal visual acuity recovered to 1

  14. Corneal Graft Rejection: Incidence and Risk Factors

    Directory of Open Access Journals (Sweden)

    Alireza Baradaran-Rafii

    2008-12-01

    Full Text Available

    PURPOSE: To determine the incidence and risk factors of late corneal graft rejection after penetrating keratoplasty (PKP. METHODS: Records of all patients who had undergone PKP from 2002 to 2004 without immunosuppressive therapy other than systemic steroids and with at least one year of follow up were reviewed. The role of possible risk factors such as demographic factors, other host factors, donor factors, indications for PKP as well as type of rejection were evaluated. RESULTS: During the study period, 295 PKPs were performed on 286 patients (176 male, 110 female. Mean age at the time of keratoplasty was 38±20 (range, 40 days to 90 years and mean follow up period was 20±10 (range 12-43 months. Graft rejection occurred in 94 eyes (31.8% at an average of 7.3±6 months (range, 20 days to 39 months after PKP. The most common type of rejection was endothelial (20.7%. Corneal vascularization, regrafting, anterior synechiae, irritating sutures, active inflammation, additional anterior segment procedures, history of trauma, uncontrolled glaucoma, prior graft rejection, recurrence of herpetic infection and eccentric grafting increased the rate of rejection. Patient age, donor size and bilateral transplantation had no significant influence on graft rejection. CONCLUSION: Significant risk factors for corneal graft rejection include

  15. Comparison of Central Corneal Thickness Measured by Standard Ultrasound Pachymetry, Corneal Topography, Tono-Pachymetry and Anterior Segment Optical Coherence Tomography.

    Science.gov (United States)

    González-Pérez, Javier; Queiruga Piñeiro, Juan; Sánchez García, Ángelx; González Méijome, José Manuel

    2018-04-10

    To compare central corneal thickness (CCT) measured by standard ultrasound pachymetry (USP), and three non-contact devices in healthy eyes. A cross-sectional study of CCT measurement in 52 eyes of 52 healthy volunteers was done by a single examiner at Ocular Surface and Contact Lens Laboratory. Three consecutive measurements were done by standard USP, non-contact tono-pachymeter, Pentacam corneal topographer, and Anterior Segment Optical Coherence Tomography (AS-OCT). The mean values were used for assessment. The results were compared using multivariate ANOVA, linear regression, and Pearson correlation. Agreement among the devices was analyzed using mean differences and Bland-Altman analysis with 95% limits of agreement (LoA). Finally, reliability was analyzed using intraclass correlation coefficient (ICC). Mean CCT by ultrasound pachymeter, tono-pachymeter, corneal topographer and AS-OCT were 558.9 ± 31.2 µm, 525.8 ± 43.1 µm, 550.4 ± 30.5 µm, and 545.9 ± 30.5 µm respectively. There was a significant positive correlation between AS-OCT and USP (Pearson correlation = 0.957, p device, and USP. Mean CCT among USP, Pentacam and AS-OCT were comparable and had significant linear correlations. In clinical practice, these three modalities could be interchangeable in healthy patients.

  16. Application of Collagen Scaffold in Tissue Engineering: Recent Advances and New Perspectives

    Directory of Open Access Journals (Sweden)

    Chanjuan Dong

    2016-02-01

    Full Text Available Collagen is the main structural protein of most hard and soft tissues in animals and the human body, which plays an important role in maintaining the biological and structural integrity of the extracellular matrix (ECM and provides physical support to tissues. Collagen can be extracted and purified from a variety of sources and offers low immunogenicity, a porous structure, good permeability, biocompatibility and biodegradability. Collagen scaffolds have been widely used in tissue engineering due to these excellent properties. However, the poor mechanical property of collagen scaffolds limits their applications to some extent. To overcome this shortcoming, collagen scaffolds can be cross-linked by chemical or physical methods or modified with natural/synthetic polymers or inorganic materials. Biochemical factors can also be introduced to the scaffold to further improve its biological activity. This review will summarize the structure and biological characteristics of collagen and introduce the preparation methods and modification strategies of collagen scaffolds. The typical application of a collagen scaffold in tissue engineering (including nerve, bone, cartilage, tendon, ligament, blood vessel and skin will be further provided. The prospects and challenges about their future research and application will also be pointed out.

  17. Structural aspects of fish skin collagen which forms ordered arrays via liquid crystalline states.

    Science.gov (United States)

    Giraud-Guille, M M; Besseau, L; Chopin, C; Durand, P; Herbage, D

    2000-05-01

    The ability of acid-soluble type I collagen extracts from Soleidae flat fish to form ordered arrays in condensed phases has been compared with data for calf skin collagen. Liquid crystalline assemblies in vitro are optimized by preliminary treatment of the molecular population with ultrasounds. This treatment requires the stability of the fish collagen triple helicity to be controlled by X-ray diffraction and differential scanning calorimetry and the effect of sonication to be evaluated by viscosity measurements and gel electrophoresis. The collagen solution in concentrations of at least 40 mg ml(-1) showed in polarized light microscopy birefringent patterns typical of precholesteric phases indicating long-range order within the fluid collagen phase. Ultrastructural data, obtained after stabilization of the liquid crystalline collagen into a gelated matrix, showed that neutralized acid-soluble fish collagen forms cross-striated fibrils, typical of type I collagen, following sine wave-like undulations in precholesteric domains. These ordered geometries, approximating in vivo situations, give interesting mechanical properties to the material.

  18. Assembly of collagen into microribbons: effects of pH and electrolytes.

    Science.gov (United States)

    Jiang, Fengzhi; Hörber, Heinrich; Howard, Jonathon; Müller, Daniel J

    2004-12-01

    Collagen represents the major structural protein of the extracellular matrix. Elucidating the mechanism of its assembly is important for understanding many cell biological and medical processes as well as for tissue engineering and biotechnological approaches. In this work, conditions for the self-assembly of collagen type I molecules on a supporting surface were characterized. By applying hydrodynamic flow, collagen assembled into ultrathin ( approximately 3 nm) highly anisotropic ribbon-like structures coating the entire support. We call these novel collagen structures microribbons. High-resolution atomic force microscopy topographs show that subunits of these microribbons are built by fibrillar structures. The smallest units of these fibrillar structures have cross-sections of approximately 3 x 5nm, consistent with current models of collagen microfibril formation. By varying the pH and electrolyte of the buffer solution during the self-assembly process, the microfibril density and contacts formed within this network could be controlled. Under certain electrolyte compositions the microribbons and microfibers display the characteristic D-periodicity of approximately 65 nm observed for much thicker collagen fibrils. In addition to providing insight into the mechanism of collagen assembly, the ultraflat collagen matrices may also offer novel ways to bio-functionalize surfaces.

  19. Femtosecond-assisted intrastromal corneal ring implantation for keratoconus treatment: a comparison with crosslinking combination

    Directory of Open Access Journals (Sweden)

    Peter Alexander von Harbach Ferenczy

    2015-04-01

    Full Text Available Purpose: To compare visual outcomes, corneal astigmatism, and keratometric readings in patients with keratoconus who underwent intrastromal corneal ring implantation (ICRSI alone with those who underwent ICRSI combined with ultraviolet A riboflavin-mediated corneal collagen crosslinking (CXL. Methods: Pre- and post-operative best-corrected distance visual acuity (BCDVA, spherical error, cylindrical error, and mean keratometry were retrospectively compared over a period of 2 years in patients with keratoconus who underwent only ICRSI (group 1 versus those in patients who underwent combined ICRSI-CXL (group 2. Results: Thirty-two eyes of 31 patients were evaluated. CXL was performed in 10 cases (31%, and there were no complications or need for ring repositioning. BCDVA improved from 0.54 to 0.18 in the group 1 and from 0.56 to 0.17 in the group 2. Spherical and cylindrical errors and mean keratometry values significantly decreased in both groups. No patient postoperatively had visual acuity (VA of less than 20/60 on refraction, and 78% exhibited VA better than or equal to 20/40 with spectacles (72% of group 1 and 90% of group 2. Improvement in the spherical equivalent (SE value was observed in the group 1 (from -5.89 ± 3.37 preoperatively to -2.65 ± 2.65 postoperatively; p<0.05 and group 2 (from -6.91 ± 1.93 preoperatively to -2.11 ± 3.01 postoperatively; p<0.05. Conclusion: Both techniques can be considered safe and effective in improving VA and refractive SE values, in decreasing the curvature of the cone apex in the topographical analysis, and in decreasing corrected diopters postoperatively in patients with keratoconus.

  20. Intravital two-photon microscopy of immune cell dynamics in corneal lymphatic vessels.

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    Philipp Steven

    Full Text Available BACKGROUND: The role of lymphatic vessels in tissue and organ transplantation as well as in tumor growth and metastasis has drawn great attention in recent years. METHODOLOGY/PRINCIPAL FINDINGS: We now developed a novel method using non-invasive two-photon microscopy to simultaneously visualize and track specifically stained lymphatic vessels and autofluorescent adjacent tissues such as collagen fibrils, blood vessels and immune cells in the mouse model of corneal neovascularization in vivo. The mouse cornea serves as an ideal tissue for this technique due to its easy accessibility and its inducible and modifiable state of pathological hem- and lymphvascularization. Neovascularization was induced by suture placement in corneas of Balb/C mice. Two weeks after treatment, lymphatic vessels were stained intravital by intrastromal injection of a fluorescently labeled LYVE-1 antibody and the corneas were evaluated in vivo by two-photon microscopy (TPM. Intravital TPM was performed at 710 nm and 826 nm excitation wavelengths to detect immunofluorescence and tissue autofluorescence using a custom made animal holder. Corneas were then harvested, fixed and analyzed by histology. Time lapse imaging demonstrated the first in vivo evidence of immune cell migration into lymphatic vessels and luminal transport of individual cells. Cells immigrated within 1-5.5 min into the vessel lumen. Mean velocities of intrastromal corneal immune cells were around 9 µm/min and therefore comparable to those of T-cells and macrophages in other mucosal surfaces. CONCLUSIONS: To our knowledge we here demonstrate for the first time the intravital real-time transmigration of immune cells into lymphatic vessels. Overall this study demonstrates the valuable use of intravital autofluorescence two-photon microscopy in the model of suture-induced corneal vascularizations to study interactions of immune and subsequently tumor cells with lymphatic vessels under close as possible