Multi-centre evaluation of two daily disposable contact lenses.

Science.gov (United States)

Walker, Jon; Young, Graeme; Hunt, Chris; Henderson, Terri

2007-05-01

To evaluate the clinical performance of two daily disposable contact lenses: 1-DAY ACUVUE (1DA) (etafilcon A, Johnson & Johnson Vision Care) and FOCUS DAILIES with AquaComfort (FD) (nelfilcon A, CIBA Vision, Inc.), which contains a quickly released moisture enhancing agent, polyvinyl alcohol (PVA). This was a 1-week, daily wear, subject-masked, bilateral, parallel group study with subjects randomly assigned to one of two daily disposable soft contact lenses. Subjects were existing soft contact lens wearers in the age range 18-39 years with a spherical refraction between -0.50 and -6.00 D. Subjects were assessed at baseline and after 1 week. Assessments included both subjective (symptoms, wearing time, vision) and objective (lens fit and ocular health) outcomes. Twenty clinical sites enrolled 282 subjects (74% female) of whom 276 (98%) successfully completed the study. Significantly more 1DA wearers reported higher mean comfort scores than with FD (3.95 versus 3.41, respectively, Pdisposable lenses highlight that, although both lenses may be considered as clinically acceptable, these lenses should not be regarded as interchangeable.

Ocular surface displacement with and without contact lenses during non-contact tonometry.

Science.gov (United States)

Rimayanti, Ulfah; Kiuchi, Yoshiaki; Uemura, Shohei; Takenaka, Joji; Mochizuki, Hideki; Kaneko, Makoto

2014-01-01

To evaluate the displacement of the central ocular surface during non-contact tonometry with and without soft contact lenses and determine the factors associated with the displacement of the central ocular surface and intraocular pressure (IOP) reading changes caused by wearing soft contact lenses (CLs). One eye each in 21 subjects was studied. The cornea was photographed using a high-speed camera at 5,000 frames/sec during non-contact tonometry without contact lenses (NCL), with -5.0 diopters (D), -0.5 D and +5.0 D CL. The displacement of the ocular surface and the factors affecting displacement at the IOP reading and maximum displacement time were investigated. The IOP readings while wearing +5 D CL were significantly higher than those obtained while wearing -5 D CL. The ocular surface displacement between +5 D CL and other groups were significantly different. A significant positive correlation was found between the ocular surface displacement of subjects at the IOP reading time and the IOP obtained with the non-contact tonometer. A significant negative correlation was found between the ocular surface curvature and the IOP obtained using the non-contact tonometer. The radius of curvature of the ocular surface affected the displacement during the IOP reading and maximum displacement time. Our results indicate that soft contact lens use changes the ocular surface behavior and IOP readings during non-contact tonometry. The radius of curvature of the eye affects the ocular surface displacement and IOP readings in this situation.

Corneal erosions, bacterial contamination of contact lenses, and microbial keratitis.

Science.gov (United States)

Willcox, Mark D P; Naduvilath, Thomas J; Vaddavalli, Pravin K; Holden, Brien A; Ozkan, Jerome; Zhu, Hua

2010-11-01

To estimate the rate of corneal erosion coupled with gram-negative bacterial contamination of contact lenses and compare this with the rate of microbial keratitis (MK) with contact lenses. The rate of corneal erosion and contact lens contamination by gram-negative bacteria were calculated from several prospective trials. These rates were used to calculate the theoretical rate of corneal erosion happening at the same time as wearing a contact lens contaminated with gram-negative bacteria. This theoretical rate was then compared with the rates of MK reported in various epidemiological and clinical trials. Corneal erosions were more frequent during extended wear (0.6-2.6% of visits) compared with daily wear (0.01-0.05% of visits). No corneal erosions were observed for lenses worn on a daily disposable basis. Contamination rates for lenses worn on a daily disposable basis were the lowest (2.4%), whereas they were the highest for low Dk lenses worn on an extended wear basis (7.1%). The estimated rate of corneal erosions occurring at the same time as wearing lenses contaminated with gram-negative bacteria was the lowest during daily wear of low Dk lenses (1.56/10,000 [95% CI: 0.23-10.57]) and the highest during extended wear of high Dk lenses (38.55/10,000 [95% CI: 24.77-60.04]). These rates were similar in magnitude to the rates reported for MK of different hydrogel lenses worn on differing wear schedules. The coincidence of corneal erosions during lens wear with gram-negative bacterial contamination of lenses may account for the relative incidence of MK during lens wear with different lens materials and modes of use.

In vitro power profiles of daily disposable contact lenses.

Science.gov (United States)

Belda-Salmerón, Lurdes; Madrid-Costa, David; Ferrer-Blasco, Teresa; García-Lázaro, Santiago; Montés-Micó, Robert

2013-10-01

To evaluate and compare the distribution of refractive power within the optic zone of different soft contact lenses and to investigate the effect of lens decentration on the power profiles. The Nimo TR1504 instrument was used to measure the optical power across different aperture diameters (from 1.5mm to 5.5mm in steps of 0.5mm) of four daily disposable contact lenses: DAILIES TOTAL1, Proclear 1-Day, SofLens daily disposable and 1-DAY ACUVUE MOIST. Measurements were performed using a wet cell. Power data were evaluated when contact lenses were in its centered position and after inducing different amounts of lens decentration (from 0.2mm to 1.0mm in steps of 0.2mm). All contact lenses showed an increase - more negative - in lens power with distance from the lens center. The amount of change varied depending on the lens. It was about 10% of lens power for DAILIES TOTAL1 (-0.29diopters (D)), SofLens daily disposable (-0.36D), and Proclear 1-Day (-0.32D) whereas 1-DAY ACUVUE MOIST showed a percentage variation of 3.3% (-0.10D). After inducing a lens decentration up to 1mm, the power curves were shifted in the negative direction. However, the change obtained in lens power compared with well-centered position was always lower than a quarter of diopter both for all the lenses and aperture diameters. Our results showed a variation of the refractive power from the lens center, becoming more negative toward the periphery, with a negligible effect of the decentration for all disposable contact lenses studied. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Power profiles of single vision and multifocal soft contact lenses.

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Wagner, Sandra; Conrad, Fabian; Bakaraju, Ravi C; Fedtke, Cathleen; Ehrmann, Klaus; Holden, Brien A

2015-02-01

The purpose of this study was to investigate the optical zone power profile of the most commonly prescribed soft contact lenses to assess their potential impact on peripheral refractive error and hence myopia progression. The optical power profiles of six single vision and ten multifocal contact lenses of five manufacturers in the powers -1.00 D, -3.00 D, and -6.00 D were measured using the SHSOphthalmic (Optocraft GmbH, Erlangen, Germany). Instrument repeatability was also investigated. Instrument repeatability was dependent on the distance from the optical centre, manifesting unreliable data for the central 1mm of the optic zone. Single vision contact lens measurements of -6.00 D lenses revealed omafilcon A having the most negative spherical aberration, lotrafilcon A having the least. Somofilcon A had the highest minus power and lotrafilcon A the biggest deviation in positive direction, relative to their respective labelled powers. Negative spherical aberration occurred for almost all of the multifocal contact lenses, including the centre-distance designs etafilcon A bifocal and omafilcon A multifocal. Lotrafilcon B and balafilcon A seem to rely predominantly on the spherical aberration component to provide multifocality. Power profiles of single vision soft contact lenses varied greatly, many having a negative spherical aberration profile that would exacerbate myopia. Some lens types and powers are affected by large intra-batch variability or power offsets of more than 0.25 dioptres. Evaluation of power profiles of multifocal lenses was derived that provides helpful information for prescribing lenses for presbyopes and progressing myopes. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

A Laboratory Assessment of Factors That Affect Bacterial Adhesion to Contact Lenses

OpenAIRE

Dutta, Debarun; Willcox, Mark DP

2013-01-01

Adhesion of pathogenic microbes, particularly bacteria, to contact lenses is implicated in contact lens related microbial adverse events. Various in vitro conditions such as type of bacteria, the size of initial inoculum, contact lens material, nutritional content of media, and incubation period can influence bacterial adhesion to contact lenses and the current study investigated the effect of these conditions on bacterial adhesion to contact lenses. There was no significant difference in num...

A Laboratory Assessment of Factors That Affect Bacterial Adhesion to Contact Lenses

Science.gov (United States)

Dutta, Debarun; Willcox, Mark DP

2013-01-01

Adhesion of pathogenic microbes, particularly bacteria, to contact lenses is implicated in contact lens related microbial adverse events. Various in vitro conditions such as type of bacteria, the size of initial inoculum, contact lens material, nutritional content of media, and incubation period can influence bacterial adhesion to contact lenses and the current study investigated the effect of these conditions on bacterial adhesion to contact lenses. There was no significant difference in numbers of bacteria that adhered to hydrogel etafilcon A or silicone hydrogel senofilcon A contact lenses. Pseudomonas aeruginosa adhered in higher numbers compared to Staphylococcus aureus. Within a genera/species, adhesion of different bacterial strains did not differ appreciably. The size of initial inoculum, nutritional content of media, and incubation period played significant roles in bacterial adhesion to lenses. A set of in vitro assay conditions to help standardize adhesion between studies have been recommended. PMID:24833224

A Laboratory Assessment of Factors That Affect Bacterial Adhesion to Contact Lenses

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Debarun Dutta

2013-11-01

Full Text Available Adhesion of pathogenic microbes, particularly bacteria, to contact lenses is implicated in contact lens related microbial adverse events. Various in vitro conditions such as type of bacteria, the size of initial inoculum, contact lens material, nutritional content of media, and incubation period can influence bacterial adhesion to contact lenses and the current study investigated the effect of these conditions on bacterial adhesion to contact lenses. There was no significant difference in numbers of bacteria that adhered to hydrogel etafilcon A or silicone hydrogel senofilcon A contact lenses. Pseudomonas aeruginosa adhered in higher numbers compared to Staphylococcus aureus. Within a genera/species, adhesion of different bacterial strains did not differ appreciably. The size of initial inoculum, nutritional content of media, and incubation period played significant roles in bacterial adhesion to lenses. A set of in vitro assay conditions to help standardize adhesion between studies have been recommended.

Extended release of hyaluronic acid from hydrogel contact lenses for dry eye syndrome.

Science.gov (United States)

Maulvi, Furqan A; Soni, Tejal G; Shah, Dinesh O

2015-01-01

Current dry eye treatment includes delivering comfort enhancing agents to the eye via eye drops, but low residence time of eye drops leads to low bioavailability. Frequent administration leads to incompliance in patients, so there is a great need for medical device such as contact lenses to treat dry eye. Studies in the past have demonstrated the efficacy of hyaluronic acid (HA) in the treatment of dry eyes using eye drops. In this paper, we present two methods to load HA in hydrogel contact lenses, soaking method and direct entrapment. The contact lenses were characterized by studying their optical and physical properties to determine their suitability as extended wear contact lenses. HA-laden hydrogel contact lenses prepared by soaking method showed release up to 48 h with acceptable physical and optical properties. Hydrogel contact lenses prepared by direct entrapment method showed significant sustained release in comparison to soaking method. HA entrapped in hydrogels resulted in reduction in % transmittance, sodium ion permeability and surface contact angle, while increase in % swelling. The impact on each of these properties was proportional to HA loading. The batch with 200-μg HA loading showed all acceptable values (parameters) for contact lens use. Results of cytotoxicity study indicated the safety of hydrogel contact lenses. In vivo pharmacokinetics studies in rabbit tear fluid showed dramatic increase in HA mean residence time and area under the curve with lenses in comparison to eye drop treatment. The study demonstrates the promising potential of delivering HA through contact lenses for the treatment of dry eye syndrome.

The Effect of Various Contact Lenses on Intraocular Pressure Measurement by Goldman Tonometer

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Monireh Mahjoob

2014-06-01

Full Text Available Background: Today, contact lenses have extensive usages. Contact lens places on cornea, so it may induce variation on cornea and these variations can influence the measurement of intraocular pressure (IOP by Goldman tonometer. The aim of this research was to study the effect of various contact lenses on measurement of intraocular pressure by Goldman tonometer. Materials and Methods: In this study, 80 subjects aged 18-25 were selected randomly among patients of Al-Zahra ophthalmology center. None of them has any eye pathological problems. Before wearing the lens, intraocular pressure was measured, and then patients were divided into two groups of soft and hard contact lenses. Soft and hard contact lenses were placed on the eye for two hours, and the intraocular pressure was measured again. Results: The mean of IOP before wearing contact lenses and two hours later was 15.96 mmHg and 13.93, s respectively. Paired test showed a significant difference between IOP before and after wearing contact lenses (p=0.001.There was no significant differences in mean of intraocular pressure decline before and after placing the contact lens in both soft and hard lenses. Conclusion: According to this study, the intraocular pressure decreases after wearing contact lenses (CL. This decline may be due to variation in properties of cornea after wearing CL that can also affect IOP measurement.

Effect of cholesterol deposition on bacterial adhesion to contact lenses.

Science.gov (United States)

Babaei Omali, Negar; Zhu, Hua; Zhao, Zhenjun; Ozkan, Jerome; Xu, Banglao; Borazjani, Roya; Willcox, Mark D P

2011-08-01

To examine the effect of cholesterol on the adhesion of bacteria to silicone hydrogel contact lenses. Contact lenses, collected from subjects wearing Acuvue Oasys or PureVision lenses, were extracted in chloroform:methanol (1:1, v/v) and amount of cholesterol was estimated by thin-layer chromatography. Unworn lenses were soaked in cholesterol, and the numbers of Pseudomonas aeruginosa strains or Staphylococcus aureus strains that adhered to the lenses were measured. Cholesterol was tested for effects on bacterial growth by incubating bacteria in medium containing cholesterol. From ex vivo PureVision lenses, 3.4 ± 0.3 μg/lens cholesterol was recovered, and from Acuvue Oasys lenses, 2.4 ± 0.2 to 1.0 ± 0.1 μg/lens cholesterol was extracted. Cholesterol did not alter the total or viable adhesion of any strain of P. aeruginosa or S. aureus (p > 0.05). However, worn PureVision lenses reduced the numbers of viable cells of P. aeruginosa (5.8 ± 0.4 log units) compared with unworn lenses (6.4 ± 0.2 log units, p = 0.001). Similarly, there were fewer numbers of S. aureus 031 adherent to worn PureVision (3.05 ± 0.8 log units) compared with unworn PureVision (4.6 ± 0.3 log units, p = 0.0001). Worn Acuvue Oasys lenses did not affect bacterial adhesion. Cholesterol showed no effect on the growth of any test strain. Although cholesterol has been shown to adsorb to contact lenses during wear, this lipid does not appear to modulate bacterial adhesion to a lens surface.

Ocular surface displacement with and without contact lenses during non-contact tonometry.

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Ulfah Rimayanti

Full Text Available PURPOSE: To evaluate the displacement of the central ocular surface during non-contact tonometry with and without soft contact lenses and determine the factors associated with the displacement of the central ocular surface and intraocular pressure (IOP reading changes caused by wearing soft contact lenses (CLs. METHODS: One eye each in 21 subjects was studied. The cornea was photographed using a high-speed camera at 5,000 frames/sec during non-contact tonometry without contact lenses (NCL, with -5.0 diopters (D, -0.5 D and +5.0 D CL. The displacement of the ocular surface and the factors affecting displacement at the IOP reading and maximum displacement time were investigated. RESULTS: The IOP readings while wearing +5 D CL were significantly higher than those obtained while wearing -5 D CL. The ocular surface displacement between +5 D CL and other groups were significantly different. A significant positive correlation was found between the ocular surface displacement of subjects at the IOP reading time and the IOP obtained with the non-contact tonometer. A significant negative correlation was found between the ocular surface curvature and the IOP obtained using the non-contact tonometer. The radius of curvature of the ocular surface affected the displacement during the IOP reading and maximum displacement time. CONCLUSIONS: Our results indicate that soft contact lens use changes the ocular surface behavior and IOP readings during non-contact tonometry. The radius of curvature of the eye affects the ocular surface displacement and IOP readings in this situation.

Practitioner Perceptions of Patients Wearing Decorative Contact Lenses Purchased Through Unauthorized Sellers.

Science.gov (United States)

Gaiser, Hilary; Ho, Connie; Janier, Nicole; Wee, Amy; Johnson, Catherine; Watanabe, Ronald

2017-03-01

To describe practitioner experiences regarding ocular complications in patients wearing decorative contact lenses, and to investigate the compliance of unauthorized distributors of decorative contact lenses to current Food and Drug Administration (FDA) and Federal Trade Commission (FTC) regulations. Also, to provide data to support a more targeted public health approach to reducing the incidence of illegal contact lens sales and associated ocular complications. An institutional review board-approved online survey was distributed through mass email to a list of 98 optometrists in the Boston, MA area. Concurrently, an empirical evaluation of independent, online decorative contact lens sellers who were not associated with FDA-approved contact lens manufacturers was performed to determine their adherence to FDA and FTC guidelines. The first 18 noncoincidental websites that resulted from a Google search for "costume contact lens sellers" and "cosmetic contact lens sellers" were examined as to the brands and parameters of lenses being sold, whether or not a valid prescription was required or verified, and if consumer education was provided. Twenty-two optometrists completed the online survey. Seventy-seven percent of respondents reported having patients with complications from decorative contact lenses that were purchased both legally and illegally. The most common age group for complications was 18 to 25 years (61%). One third of complications were seen in first-time lens wearers, half of whom never received proper care instructions or were unaware that care instructions existed. One quarter of the lenses were purchased illegally with unlicensed stores being the most common place of purchase. Of the 18 online sites examined, 72% of sellers failed to adhere to FTC and FDA regulations. A significant number of individuals who obtain contact lenses illegally from unauthorized sources are young adults. Most unauthorized sellers reviewed did not adhere to the proper protocol

Protein deposition and its effect on bacterial adhesion to contact lenses.

Science.gov (United States)

Omali, Negar Babaei; Zhu, Hua; Zhao, Zhenjun; Willcox, Mark D P

2013-06-01

Bacterial adhesion to contact lenses is believed to be the initial step for the development of several adverse reactions that occur during lens wear such as microbial keratitis. This study examined the effect of combinations of proteins on the adhesion of bacteria to contact lenses. Unworn balafilcon A and senofilcon A lenses were soaked in commercially available pure protein mixtures to achieve the same amount of various proteins as found ex vivo. These lenses were then exposed to Pseudomonas aeruginosa and Staphylococcus aureus. Following incubation, the numbers of P. aeruginosa or S. aureus that adhered to the lenses were measured. The possible effect of proteins on bacterial growth was investigated by incubating bacteria in medium containing protein. Although there was a significant (p lenses soaked in the lysozyme/lactoferrin combination, the protein adhered to lenses did not alter the adhesion of any other strains of P. aeruginosa or S. aureus (p > 0.05). Growth of S. aureus 031 (p 0.05). Adsorption of amounts of lysozyme and lactoferrin or lipocalin equivalent to those extracted from worn contact lenses did not affect the adhesion of most strains of S. aureus or P. aeruginosa to lens surfaces.

Adherence of Pseudomonas aeruginosa to contact lenses

International Nuclear Information System (INIS)

Miller, M.J.

1988-01-01

The purpose of this research was to examined the interactions of P. aeruginosa with hydrogel contact lenses and other substrata, and characterize adherence to lenses under various physiological and physicochemical conditions. Isolates adhered to polystyrene, glass, and hydrogel lenses. With certain lens types, radiolabeled cells showed decreased adherence with increasing water content of the lenses, however, this correlation with not found for all lenses. Adherence to rigid gas permeable lenses was markedly greater than adherence to hydrogels. Best adherence occurred near pH 7 and at a sodium chloride concentration of 50 mM. Passive adhesion of heat-killed cells to hydrogels was lower than the adherence obtained of viable cells. Adherence to hydrogels was enhanced by mucin, lactoferrin, lysozyme, IgA, bovine serum albumin, and a mixture of these macromolecules. Adherence to coated and uncoated lenses was greater with a daily-wear hydrogel when compared with an extended-wear hydrogel of similar polymer composition. Greater adherence was attributed to a higher concentration of adsorbed macromolecules on the 45% water-content lens in comparison to the 55% water-content lens

Soft contact lenses: Basic characteristics, advantages and complications associated with their use

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Milosavljević Miloš

2016-01-01

Full Text Available Soft contact lenses have an important place in ophthalmology, both for the correction of refractive anomalies and tor the treatment of some eye diseases. From the moment when adequately biocompatible materials were found, for a very sensitive environment such as the human eye, from early 60s of the 20th century, starts irrepressible expansion of soft contact lenses. The reason for this expansion of soft contact lenses lies in advantages they undoubtedly have in comparison to glasses, but also in comparison to hard and semi-hard contact lenses. Unfortunately, in parallel with the increasing number of users of this type of optical aids, increases the incidence of complications that can arise. Complications can be very diverse in nature and severity, and they can be classified into three major groups: symptoms of eye dryness, infections and allergic-toxic complications. Symptoms of dry eye are very common for users of contact lenses, and their occurrence is especially provoked by certain factors, such as cigarette smoke or prolonged watching the computer screen or TV. These complications are usually not so dangerous and can easily be solved by applying artificial tears. Infections are not so common and occur as a result of inadequate maintenance of contact lenses. If the symptoms are recognized early, infections are mostly stopped at the level of conjunctivitis and are treated fairly quickly and easily. Otherwise, the infection can progress to ulcerative keratitis, the most severe complication of inadequate application of soft contact lenses, and in some cases it can even lead to blindness. Allergic-toxic complications generally occur in susceptible persons and their occurrence in most cases means contraindication for further wearing of soft contact lenses. This case report underlines possible role of rheumatoid factor in estimation of the patient's response to administered therapy.

Contact lenses purchased over the internet place individuals potentially at risk for harmful eye care practices.

Science.gov (United States)

Fogel, Joshua; Zidile, Chaya

2008-01-01

Individuals are increasingly purchasing contact lenses over the Internet. No studies exist regarding Internet purchase of contact lenses and eye care health practices. One hundred fifty-one college students were surveyed regarding contact lenses purchase category (doctor's office, store, Internet). Pearson chi-square analyses compared purchase category with responses regarding U.S. Food and Drug Administration (FDA) recommendations for purchasing contact lenses online. Analysis of variance compared contact lenses purchase category with the Time Pressure Scale (TPS). Also, correlation analyses compared the TPS with Internet eye-health statements. Contact lens purchase categories included doctor's office (43.0%), store (55.0%), and Internet (22.5%), with individuals purchasing at multiple venues. With regard to the FDA recommendations, those who purchased contact lenses at a doctor's office more often adhered to the recommendations, whereas those who purchased contact lenses at a store or the Internet did so less often. Those who purchased contact lenses over the Internet had significantly higher TPS scores. In addition, higher TPS scores were significantly correlated with various statements regarding the Internet. Those who purchase contact lenses via the Internet or store do not follow a number of FDA contact lenses recommendations. Also, those with higher TPS scores trust possible non-evidence-based contact lenses Internet information. Implications with regard to the Fairness to Contact Lens Consumers Act are discussed.

Use of Contact Lenses in Eyes with Severe Keratoconus: Long-term Results

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Zerrin Tuncer

2012-05-01

Full Text Available Pur po se: To evaluate the long-term results of rigid gas permeable (RGP contact lenses in severe keratoconic eyes. Ma te ri al and Met hod: Severe keratoconic eyes with RGP contact lenses were evaluated retrospectively. Re sults: Long-term follow-up results of RGP contact lenses applied to 59 eyes of 42 patients (25 women, 17 men with a diagnosis of severe keratoconus were analyzed. Follow-up period was 3 to 12 years (mean: 6.57±3.60. The mean age at first exam was 25.88±9.10 years, the mean corneal curve K1 was 6.49±0.40 mm and K2 was 5.91±0.40 mm. Mean visual acuities with spectacles and contact lenses were 0.26±0.10 lines (0.63±0.20 logMAR and 0.66±0.20 lines (0.20±0.10 logMAR, respectively. The difference between both visual acuities was statistically significant (p=0.0001. At the last visit, the mean visual acuity with RGP contact lenses was 0.68±0.20 lines (0.19±0.10 logMAR. There was no statistically significant difference in visual acuity between first and last examinations with contact lenses (p=0.32. During the long-term follow-up period, apical scarring developed in 17 eyes. Only the 2 eyes of one patient needed penetrating keratoplasty after 6 years of RGP contact lens use. Dis cus si on: Use of RGP contact lenses should be considered before penetrating keratoplasty in cases of severe keratoconus. (Turk J Ophthalmol 2012; 42: 202-6

Management of complications associated with lathe-cut soft contact lenses.

Science.gov (United States)

Freeman, M I

1979-06-01

At the present time, nine lathe-cut lenses are FDA approved and commercially available in the United States. Complications of lathe-cut soft contact lenses cover a wide spectrum of problems. Five significant complications of lathe-cut lenses and their prevention and therapeutic management are discussed.

The effect of UV-blocking contact lenses as a therapy for canine chronic superficial keratitis.

Science.gov (United States)

Denk, Nora; Fritsche, Jens; Reese, Sven

2011-05-01

To evaluate the effect of UV-blocking soft contact lenses in treatment for chronic superficial keratitus (CSK). Twenty six dogs with CSK were treated continuously with UV-blocking contact lenses for 6 months. A contact lens was placed on one eye of each dog; the other eye remained without a lens as a control eye. After this primary study, five of the dogs were further treated and they wore then contact lenses in both eyes. Continuously, all patients were concurrently treated topically with cyclosporine. The contact lenses were changed every 4 weeks and an ophthalmic examination performed. Evaluation criteria included corneal alterations as pigmentation, edema, pannus and vascularization. To determine the transmittance characteristics of the contact lenses before and after use, 32 contact lenses were measured with a UV-vis-NIR spectrophotometer. Pigmentation increased in eyes wearing lenses and in control eyes over the evaluation period of 6 months. Corneal edema increased in the eyes wearing lenses, but remained unaffected in the control eyes. A significant difference in the incidence of pannus and the extent of corneal vascularisation could not be evaluated. Adverse effects were noted in six cases (corneal edema and vascularisation, conjunctivitis, blepharospasm). All new lenses studied reduced UV-radiation to a safe level, whereas used lenses did not maintain their transmittance characteristics. No positive effect of UV-blocking contact lenses could be proven with the study design used. © 2011 American College of Veterinary Ophthalmologists.

High-Dk piggyback contact lenses over Intacs for keratoconus: a case report.

Science.gov (United States)

Smith, Kyle A; Carrell, James D

2008-07-01

The authors describe a case of a keratoconic patient with Intacs fitted with a high-Dk piggyback contact lens system. A 41-year-old man presented to the clinic 1 week after Intacs surgery for keratoconus with complaints of poor visual acuity (VA) and monocular polyopia OU. The patient was corrected to 20/30 in both eyes with rigid gas permeable contact lenses but could not tolerate the lenses for more than 8 hours OD and 2 hours OS. The patient was then successfully fit with a high-Dk piggyback contact lens system. The patient was able to wear the piggyback contact lenses comfortably 12 to 18 hours per day and was corrected to 20/25 OD, 20/30 OS, and 20/20 OU. Patients with Intacs for keratoconus may require a combination of soft and rigid contact lenses for the best possible VA. Contact lens fitting with a high-Dk piggyback contact lens system can provide optimal comfort, corneal health, and VA for patients with Intacs for keratoconus.

Bacteria and parasites in contact lenses of asymptomatic wearers in Nigeria

OpenAIRE

Emina, Michael Osita; Idu, Faustina Kemdinum

2011-01-01

Purpose: This is to determine the prevalence of bacterial and parasitic flora in asymptomatic disposable and extended contact lens wearers in Lagos State, Nigeria. Methods: The study was carried out on 156 contact lenses from 78 asymptomatic wearers between the ages of 12 to 38 years. Eighty two disposable daily wear (DWCL) and 74 extended wear (EWCL) contact lenses were examined. The contact lenses’ swabs and the trays were transferred to the laboratory for microbial examination. Resul...

Effect of phospholipid deposits on adhesion of bacteria to contact lenses.

Science.gov (United States)

Babaei Omali, Negar; Proschogo, Nicholas; Zhu, Hua; Zhao, Zhenjun; Diec, Jennie; Borazjani, Roya; Willcox, Mark D P

2012-01-01

Protein and lipid deposits on contact lenses may contribute to clinical complications. This study examined the effect of phospholipids on the adhesion of bacteria to contact lenses. Worn balafilcon A (n = 11) and senofilcon A (n = 11) were collected after daily wear and phospholipids were extracted in chloroform:methanol. The amount of phospholipid was measured by electrospray ionization mass spectrometry. Unworn lenses soaked in phospholipids were exposed to Pseudomonas aeruginosa and Staphylococcus aureus. After 18 h incubation, the numbers of P. aeruginosa or S. aureus that adhered to the lenses were measured. Phospholipid was tested for possible effects on bacterial growth. A broad range of sphingomyelins (SM) and phosphatidylcholines (PC) were detected from both types of worn lenses. SM (16:0) (m/z 703) and PC (34:2) (m/z 758) were the major phospholipids detected in the lens extracts. Phospholipids did not alter the adhesion of any strain of P. aeruginosa or S. aureus (p > 0.05). Phospholipids (0.1 mg/mL) showed no effect on the growth of P. aeruginosa 6294 or S. aureus 031. Phospholipids adsorb/absorb to contact lenses during wear, however, the major types of phospholipids adsorbed to lenses do not alter bacterial adhesion or growth.

The effects of two different types of bandage contact lenses on the healthy canine eye.

Science.gov (United States)

Braus, Barbara Katharina; Riedler, Daniela; Tichy, Alexander; Spergser, Joachim; Schwendenwein, Ilse

2018-02-06

To compare two types of bandage contact lenses on the healthy canine eye. Six healthy Beagles. Two different types of bandage contact lenses (single sized human silicone contact lens 'PureVision 2' (Bausch & Lomb Incorporated, Rochester, NY, USA) and specially designed veterinary hydrogel contact lens 'AcriVet Pat D' (Bausch & Lomb Incorporated) were placed in 12 eyes of healthy Beagle dogs. Retention times and the effects of the lenses regarding irritation of the eye, changes in tear production, impact of contact lenses on tonometric readings, and cytologic and microbiological alterations of the canine eye were investigated. Mean retention times for veterinary hydrogel lenses with special dimensions were significantly shorter (2 days) than for one size human silicon lenses (8.8 days). Irritation scores were overall low for both types of lenses apart from one human lens causing severe irritation and keratoconjunctivitis as a sequel to folding and displacement. Tear production remained stable in human contact lenses. Intraocular pressure readings with a contact lens in place were only slightly altered; the most accurate readings were obtained through a human lens with an applanation tonometer. Cytology revealed a slight, nonsignificant increase in neutrophilic granulocytes with both types of lenses; the microflora did not change significantly. Human silicone lenses have significantly longer retention times and are less expensive than veterinary hydrogel lenses. In regard to irritation, bacterial growth and inflammation, both types of lenses can be recommended for use in canine eyes. © 2018 American College of Veterinary Ophthalmologists.

Consequences of wear interruption for discomfort with contact lenses.

Science.gov (United States)

Papas, Eric B; Tilia, Daniel; Tomlinson, Daniel; Williams, Josh; Chan, Eddy; Chan, Jason; Golebiowski, Blanka

2014-01-01

To establish whether increased end-of-day discomfort during soft contact lens wear is associated with short-term changes occurring to the lens itself. Twenty-seven subjects wore hydrogel lenses (Focus Dailies; Alcon) bilaterally for 10 hours on two separate days. Comfort was reported using 1-100 numerical rating scales (1 = intolerable discomfort, 100 = lens cannot be felt). Day 1 ratings were taken before lens insertion and at 0.05, 5, and 10 hours post-insertion. Day 2 ratings occurred at similar times, but lenses were removed after the 5-hour assessment and either reinserted (n = 14) or newly replaced (n = 12). An additional rating was taken 5 minutes after re-insertion. Wear then continued to the 10-hour point. In a separate study, 24 different subjects repeated these procedures using a silicone hydrogel lens (AirOptix Aqua; Alcon) with wear taking place on 3 days to permit lens replacement to be with existing as well as new lenses in all subjects. For hydrogel lenses, comfort scores (mean ± 95% CI) reported after 10 hours were 79.4 ± 8.3 when lenses were worn un-replaced, compared with 73.2 ± 9.2 for replacement with the existing lens. When replacement was with a brand new lens, the corresponding values were 72.9 ± 10.9 (un-replaced) versus 69.2 ± 12.8 (new lens replacement). For silicone hydrogel lenses, 10-hour comfort was 90.3 ± 3.2 (un-replaced) versus 92.2 ± 2.9 (replacement with existing lens) versus 90.0 ± 3.3 (replacement with new lens). Differences between replacement conditions were not significant in any case (analysis of variance, p > 0.05). Final comfort was not influenced by replacing lenses midway through the wearing period. Comfort decrements experienced by users of these daily contact lenses towards the later part of the wearing period are not caused by changes occurring to the lenses on this time scale. Possible alternative etiological factors include a fatigue-like response in one or more ocular tissues or stimulation of ocular

Microbiologic study of soft contact lenses after laser subepithelial keratectomy for myopia.

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Hondur, Ahmet; Bilgihan, Kamil; Cirak, Meltem Yalinay; Dogan, Ozgur; Erdinc, Alper; Hasanreisoglu, Berati

2008-01-01

To evaluate the extent and agents of bacterial contamination of bandage disposable soft contact lenses after laser subepithelial keratectomy (LASEK) and to correlate the findings with clinical data. Disposable soft contact lenses were collected from 52 eyes of 26 consecutive patients treated with LASEK for myopia. The patients were treated with a fixed combination of tobramycin and diclofenac until epithelial closure. The lenses were removed on the fourth or fifth postoperative day with sterile forceps and immediately placed in sterile tubes containing culture media brain-heart infusion broth. The lenses were evaluated for microbial colonization. Of the 52 contact lenses analyzed, six (11.5%) had positive cultures. However, no clinical finding of infection was noted. Isolated microorganisms were coagulase-negative staphylococci (two lenses), Stenotrophomonas maltophilia (two lenses), Acinetobacter species (one lens), and Aeromonas hydrophila (one lens). Except for one case, the microorganisms were sensitive to the administered antibiotic. The risk of infectious keratitis after LASEK seems to be low. Except for staphylococci, the isolated microorganisms have not been previously reported to colonize the ocular surface or cause keratitis after refractive surgery. These findings may suggest a changing trend of potentially infectious agents after surface ablation.

Compliance as factor for prevent complications of using of contact lenses

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E. Y. Markova

2015-01-01

Full Text Available The main goal of this study is to identify the role of compliance in the prevention of complications while wearing soft contact lenses (SCL. 2257 patients in the «Center of vision correction contact» were examined. The age of patients was from12 till 46 years. 58 % female, 42 % male. 47.5 % patients were using daily disposable lenses, 52.5 % — lenses of planned replacement: 23.4 % — 2 weeks, 25.1 % — 1 month, 4 % — 3 months. All patients were using SCL for at least 1 year. The benefits of contact lens are compared with the glasses by different authors. However, any contact lens are a foreign body for the eye, which requires special care, and in case of non-compliance with the doctor’s recommendations may cause the complications. This study has shown that compliance among patients using contact lenses is below 50 %. The main reason for noncompliance of patients is the lack of time and attention to the health of patients. For achievement of compliance and prevention of complications of contact lens is recommended to regularly take the following necessary measures: patient education, explaining to him the need for each stage of lens care, which increases motivation. At the same time, the learning process can be demonstrated to have complications arise in the case of disturbances. Optimization of individual therapeutic program, which is the correct selection of contact lenses and care products tailored to the individual needs of the patient, his lifestyle and personal finance. However, the risk of complications depends not only on the doctor or the manufacturer, but to a greater extent on the patient. In other words, compliance — a necessary condition for ensuring the effectiveness of contact lens and avoiding the occurrence of complications.

Oxygen, water, and sodium chloride transport in soft contact lenses materials.

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Gavara, Rafael; Compañ, Vicente

2017-11-01

Oxygen permeability, diffusion coefficient of the sodium ions and water flux and permeability in different conventional hydrogel (Hy) and silicone-hydrogel (Si-Hy) contact lenses have been measured experimentally. The results showed that oxygen permeability and transmissibility requirements of the lens have been addressed through the use of siloxane containing hydrogels. In general, oxygen and sodium chloride permeability values increased with the water content of the lens but there was a percolation phenomenon from a given value of water uptake mainly in the Si-Hy lenses which appeared to be related with the differences between free water and bound water contents. The increase of ion permeability with water content did not follow a unique trend indicating a possible dependence of the chemical structure of the polymer and character ionic and non-ionic of the lens. Indeed, the salt permeability values for silicone hydrogel contact lenses were one order of magnitude below those of conventional hydrogel contact lenses, which can be explained by a diffusion of sodium ions occurring only through the hydrophilic channels. The increase of the ionic permeability in Si-Hy materials may be due to the confinement of ions in nanoscale water channels involving possible decreased degrees of freedom for diffusion of both water and ions. In general, ionic lenses presented values of ionic permeability and diffusivity higher than most non-ionic lenses. The tortuosity of the ionic lenses is lower than the non-ionic Si-Hy lenses. Frequency 55 and PureVision exhibited the highest water permeability and flux values and, these parameters were greater for ionic Si-Hy lenses than for ionic conventional hydrogel lenses. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2218-2231, 2017. © 2016 Wiley Periodicals, Inc.

Ultraviolet radiation for the sterilization of contact lenses

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Gritz, D.C.; Lee, T.Y.; McDonnell, P.J.; Shih, K.; Baron, N.

1990-01-01

Two sources of ultraviolet (UV) radiation with peak wavelengths in the UV-C or UV-B ranges were compared for their ability to sterilize contact lenses infected with Pseudomonas aeruginosa, Streptococcus pneumoniae, Acanthamoeba castellani, Candida albicans, and Aspergillus niger. Also examined was the effect of prolonged UV light exposure on soft and rigid gas permeable (RGP) contact lenses. The UV-C lamp (253.7 nm, 250 mW/cm2 at 1 cm) was germicidal for all organisms within 20 minutes but caused destruction of the soft lens polymers within 6 hours of cumulative exposure. UV-C caused damage to RGP lenses in less than 100 hours. The UV-B lamp (290-310 nm, 500 mW/cm2 at 1 cm) was germicidal for all organisms tested (except Aspergillus) with a 180-minute exposure and caused less severe changes in the soft lens polymers than did the UV-C lamp, although cumulative exposure of 300 hours did substantially weaken the soft lens material. RGP materials were minimally affected by exposure to 300 hours of UV-B. Ultraviolet light is an effective germicidal agent but is injurious to soft lens polymers; its possible utility in the sterilization of RGP lenses and lens cases deserves further study

Comparison of surface roughness and bacterial adhesion between cosmetic contact lenses and conventional contact lenses.

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Ji, Yong Woo; Cho, Young Joo; Lee, Chul Hee; Hong, Soon Ho; Chung, Dong Yong; Kim, Eung Kweon; Lee, Hyung Keun

2015-01-01

To compare physical characteristics of cosmetic contact lenses (Cos-CLs) and conventional contact lenses (Con-CLs) that might affect susceptibility to bacterial adhesion on the contact lens (CL) surface. Surface characteristics of Cos-CLs and Con-CLs made from the same material by the same manufacturer were measured by atomic force microscopy (AFM) and scanning electron microscopy. To determine the extent and rate of bacterial adhesion, Cos-CL and Con-CL were immersed in serum-free Roswell Park Memorial Institute media containing Staphylococcus aureus or Pseudomonas aeruginosa. Additionally, the rate of removal of adherent bacteria was evaluated using hand rubbing or immersion in multipurpose disinfecting solutions (MPDS). The mean surface roughness (root mean square and peak-to-valley value) measured by AFM was significantly higher for Cos-CL than for Con-CL. At each time point, significantly more S. aureus and P. aeruginosa adhered to Cos-CL than to Con-CL, which correlated with the surface roughness of CL. In Cos-CL, bacteria were mainly found on the tinted surface rather than on the noncolored or convex areas. Pseudomonas aeruginosa attached earlier than S. aureus to all types of CL. However, P. aeruginosa was more easily removed from the surface of CL than S. aureus by hand rubbing or MPDS soaking. Increased surface roughness is an important physical factor for bacterial adhesion in Cos-CL, which may explain why rates of bacterial keratitis rates are higher in Cos-CL users in CL physical characteristics.

Switchable Liquid Crystal Contact Lenses for the Correction of Presbyopia

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James Bailey

2018-01-01

Full Text Available Presbyopia is an age-related disorder where the lens of the eye hardens so that focusing on near objects becomes increasingly difficult. This complaint affects everyone over the age of 50. It is becoming progressively more relevant, as the average age of the global population continues to rise. Bifocal or varifocal spectacles are currently the best solution for those that require near and far vision correction. However, many people prefer not to wear spectacles and while multifocal contact lenses are available, they are not widely prescribed and can require significant adaptation by wearers. One possible solution is to use liquid crystal contact lenses that can change focal power by applying a small electric field across the device. However, the design of these contact lenses must be carefully considered as they must be comfortable for the user to wear and able to provide the required change in focal power (usually about +2D. Progress towards different lens designs, which includes lens geometry, liquid crystal choices and suitable alignment modes, are reviewed. Furthermore, we also discuss suitable electrode materials, possible power sources and suggest some methods for switching the lenses between near and far vision correction.

Microbial contamination of soft contact lenses & accessories in asymptomatic contact lens users

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Deeksha V Thakur

2014-01-01

Full Text Available Background & objectives: With increasing use of soft contact lenses the incidence of contact lens induced infections is also increasing. This study was aimed to assess the knowledge of new and existing contact lens users about the risk of microbial contamination associated with improper use and maintenance of contact lenses, type of microbial flora involved and their potential to cause ophthalmic infections. Methods: Four samples each from 50 participants (n=200 were collected from the lenses, lens care solutions, lens care solution bottles and lens cases along with a questionnaire regarding their lens use. The samples were inoculated onto sheep blood agar, Mac Conkey′s agar and Sabouraud′s dextrose agar. Organisms were identified using standard laboratory protocols. Results: Overall rate of microbial contamination among the total samples was 52 per cent. The most and the least contaminated samples were found to be lens cases (62% and lens care solution (42%, respectively. The most frequently isolated contaminant was Staphylococcus aureus (21% followed by Pseudomonas species (19.5%. Majority (64% of the participants showed medium grade of compliance to lens cleaning practices. Rate of contamination was 100 and 93.75 per cent respectively in those participants who showed low and medium compliance to lens care practices as compared to those who had high level of compliance (43.75% ( p0 <0.05. Interpretation & conclusions: Lens care practices amongst the participants were not optimum which resulted into high level contamination. Hence, creating awareness among the users about the lens care practices and regular cleaning and replacements of lens cases are required.

Contact lenses and the rate of evaporation measured in vitro; the influence of wear, squalene and wax.

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Vishnubhatla, Sravya; Borchman, Douglas; Foulks, Gary N

2012-12-01

Accelerated evaporation of tears may contribute to dry eye symptoms. It is not clear whether contact lenses decrease or increase the rate of evaporation of tears. In this study, the rates of evaporation through contact lenses (ERTCL) were measured in vitro to gain insight to this question. Contact lenses were equilibrated with various solutions to determine if they influenced ERTCL in vitro. ERTCL was measured gravimetrically. ERTCL measured in vitro for used contact lenses was about 20% faster than for buffer alone suggesting that natural tear components bound to the lenses changed the ERTCL. One natural tear component that binds to contact lenses is waxes. Equilibration of contact lenses with wax increased the ERTCL by about 30% suggesting that waxes might potentially increase ERTCL in vivo. Squalene, found in sebum and possibly meibum was infused into the contact lenses as a step toward decreasing the ERTCL. Squalene decreased ERTCL by over 60% in vitro. Soaking a contact lens in DuraSite(®) with benzalkonium chloride (BAK) did not alter the ERTCL. ERTCL were about 40% higher than the evaporation rate of DuraSite(®) alone or without BAK. In addition to lowering the ERTCL, the squalene in contact lenses could be a source of terpenoids to replace the terpenoids deficient in patients with MGD. If the ERTCL could be minimized in vivo, contact lenses could potentially be used to relieve dry eye symptoms in patients with evaporative dry eye. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

On- and off-eye spherical aberration of soft contact lenses and consequent changes of effective lens power.

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Dietze, Holger H; Cox, Michael J

2003-02-01

Soft contact lenses produce a significant level of spherical aberration affecting their power on-eye. A simple model assuming that a thin soft contact lens aligns to the cornea predicts that these effects are similar on-eye and off-eye. The wavefront aberration for 17 eyes and 33 soft contact lenses on-eye was measured with a Shack-Hartmann wavefront sensor. The Zernike coefficients describing the on-eye spherical aberration of the soft contact lens were compared with off-eye ray-tracing results. Paraxial and effective lens power changes were determined. The model predicts the on-eye spherical aberration of soft contact lenses closely. The resulting power change for a +/- 7.00 D spherical soft contact lens is +/- 0.5 D for a 6-mm pupil diameter and +/- 0.1 D for a 3-mm pupil diameter. Power change is negligible for soft contact lenses corrected for off-eye spherical aberration. For thin soft contact lenses, the level of spherical aberration and the consequent power change is similar on-eye and off-eye. Soft contact lenses corrected for spherical aberration in air will be expected to be aberration-free on-eye and produce only negligibly small power changes. For soft contact lenses without aberration correction, for higher levels of ametropia and large pupils, the soft contact lens power should be determined with trial lenses with their power and p value similar to the prescribed lens. The benefit of soft contact lenses corrected for spherical aberration depends on the level of ocular spherical aberration.

Broad spectrum antimicrobial activity of melimine covalently bound to contact lenses.

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Dutta, Debarun; Cole, Nerida; Kumar, Naresh; Willcox, Mark D P

2013-01-07

To develop a stable antimicrobial contact lens, which is effective against the International Organization for Standardization (ISO) panel microorganisms, Acanthamoeba castellanii and drug resistant strains of Pseudomonas aeruginosa and Staphylococcus aureus. Melimine was covalently incorporated into etafilcon A lenses. The amount of peptide present on the lens surface was quantified using amino acid analysis. After coating, the heat stability (121°C), lens surface hydrophobicity (by captive bubble), and in vitro cytotoxicity to mouse L929 cells of the lenses were investigated. Antimicrobial activity against the micro-organisms was evaluated by viable plate count and fluorescence microscopy, measuring the proportion of cell death compared with control lenses with no melimine. The most effective concentration was determined to be 152 ± 44 μg lens(-1) melimine on the lens surface. After coating, lenses were relatively hydrophilic and were nontoxic to mammalian cells. The activity remained high after autoclaving (e.g., 3.1, 3.9, 1.2, and 1.0 log inhibition against P. aeruginosa, S. aureus, A. castellanii, and Fusarium solani, respectively). Fluorescence microscopy confirmed significantly reduced (P bacteria to melimine contact lenses. Viable count confirmed that lenses were active against all the bacteria and fungi from the ISO panel, Acanthamoeba and gave at least 2 log inhibition against all the multidrug resistant S. aureus and P. aeruginosa strains. Melimine may offer excellent potential for development as a broad spectrum antimicrobial coating for contact lenses, showing activity against all the bacterial and fungal ISO panel microorganisms, Acanthamoeba, and antibiotic resistant strains of P. aeruginosa and S. aureus.

Antibacterial activity of contact lenses bearing surface-immobilized layers of intact liposomes loaded with levofloxacin.

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Danion, Anne; Arsenault, Isabelle; Vermette, Patrick

2007-09-01

In vitro methods to evaluate antibacterial activity were used with contact lenses bearing levofloxacin-loaded liposomes developed for the prevention and treatment of bacterial ocular infections such as keratitis. Levofloxacin was incorporated into liposomes before these intact liposomes were immobilized onto the surfaces of soft contact lenses using a multilayer immobilization strategy. The release of levofloxacin from contact lenses bearing 2, 5, and 10 layers of liposomes into a saline buffer at 37 degrees C was monitored by fluorescence. The levofloxacin release, as a function of time, was described by a mechanism taking into account two independent first-order kinetic models. The total release of levofloxacin from the contact lenses was completed within 6 days. The release of levofloxacin from contact lenses bearing 10 layers of liposomes and subsequently soaked overnight in a levofloxacin solution was also studied and compare to that of dried contact lenses without any chemical modification rehydrated in a levofloxacin solution. The antibacterial activity of the liposome-coated contact lenses against Staphylococcus aureus was evaluated by measuring (i) the diameters of the inhibition zone on an agar plate and (ii) the optical density using a broth assay. The liposome-coated lenses showed an antibacterial activity both on agar and in broth following 24 h. When initial bacteria inocula were equal or below 10(6) CFU/mL, all the bacteria were inhibited within 2 h. When using initial bacteria inocula of 10(8) CFU/mL, an initial burst release provided by soaking the liposomal lenses was required for the first hours to inhibit bacteria growth. (c) 2007 Wiley-Liss, Inc. and the American Pharmacists Association.

Isolation of coagulase-negative staphylococci from extended-wear soft contact lenses in asymptomatic patients.

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Faghri, Jamshid

2008-05-01

Coagulase-negative staphylococci and diphtheroids are normal inhabitants of the outer surface of the human eye. These microorganisms serve as part of the defense mechanism of the ocular anatomy in preventing colonization and infection by pathogenic bacteria. Nevertheless, infections associated with contaminated solutions and cases became serious problems for people who wear soft contact lenses. The aim of this study is to isolate and identify aerobic bacteria, particularly, gram-negative species associated with the use of extended-wear soft contact lenses. Extended-wear contact lenses were collected, using aseptic technique, from the eyes of individuals after 30 days of extended wear (5-7 day intermittent periods) and were examined for adhered aerobic bacteria. Coagulase-negative staphylococci were isolated from 74% of the lenses. Serratia marcescens was found at an incidence of 10% and Pseudomonas aeruginosa at an incidence of 6%. The presence of species of bacteria, including P. aeruginosa and S. marcescens, which have been associated with daily wear soft contact lenses, solutions, and cases also seem to be associated with extended-wear lenses.

Power Profiles of Commercial Multifocal Soft Contact Lenses.

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Kim, Eon; Bakaraju, Ravi C; Ehrmann, Klaus

2017-02-01

To evaluate the optical power profiles of commercially available soft multifocal contact lenses and compare their optical designs. The power profiles of 38 types of multifocal contact lenses-three lenses each-were measured in powers +6D, +3D, +1D, -1D, -3D, and -6D using NIMO TR1504 (Lambda-X, Belgium). All lenses were measured in phosphate buffered saline across 8 mm optic zone diameter. Refractive index of each lens material was measured using CLR 12-70 (Index Instruments, UK), which was used for converting measured power in the medium to in-air radial power profiles. Three basic types of power profiles were identified: center-near, center-distance, and concentric-zone ring-type designs. For most of the lens types, the relative plus with respect to prescription power was lower than the corresponding spectacle add. For some lens types, the measured power profiles were shifted by up to 1D across the power range relative to their labeled power. Most of the lenses were designed with noticeable amounts of spherical aberration. The sign and magnitude of spherical aberration can either be power dependent or consistent across the power range. Power profiles can vary widely between the different lens types; however, certain similarities were also observed between some of the center-near designs. For the more recently released lens types, there seems to be a trend emerging to reduce the relative plus with respect to prescription power, include negative spherical aberration, and keep the power profiles consistent across the power range.

Lathe-cut hydrophilic contact lenses: report of 100 clinical cases.

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Espy, J W

1978-10-01

In a review of the literature, it became apparent that there were very few articles describing the advantages, as well as the fitting techniques, of lathe-cut hydrophilic contact lenses. Few practitioners, including those who fit other types of hydrophilic lenses and hard lenses, have had any experience with this lens, and considerable interest has been generated by fragmentary reports of good results. This paper describes in detail the geometry of the first lathe-cut hydrophilic lens approved by the Federal Drug Administration, the fitting methods utilizing trial lenses, and the results of 100 patients successfully fitted.

Characterization of nanophotonic soft contact lenses based on poly (2-hydroxyethyl methacrylate and fullerene

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Debeljković Aleksandra D.

2013-01-01

Full Text Available This work presents comparative research of characteristics of a basic and new nanophotonic material, the latter of which was obtained by incorporation fullerene, C60, in the base material for soft contact lenses. The basic (SL38 and nanophotonic materials (SL38-A for soft contact lenses were obtained by radical polymerization of 2-hydroxyethyl methacrylate and 2-hydroxyethyl methacrylate and fullerene, which were derived by the technology in the production lab of the company Soleko (Milan, Italy. The materials were used for production of soft contact lenses in the company Optix (Belgrade, Serbia for the purposes of this research. Fullerene was used due to its apsorption transmission characteristics in ultraviolet, visible and near infrared spectrum. For the purposes of material characterization for potential application as soft contact lenses, network parameters were calculated and SEM analysis of the materials was performed while the optical properties of the soft contact lenses were measured by a Rotlex device. The values of the diffusion exponent, n, close to 0.5 indicated Fick's kinetics corresponding to diffusion. The investigated hydrogels could be classified as nonporous hydrogels. With Rotlex device, values of optical power and map of defects were showed. The obtained values of optical power and map of defects showed that the optical power of synthesized nanophotonic soft contact lens is identical to the nominal value while this was not the case for the basic lens. Also, the quality of the nanophotonic soft contact lens is better than the basic soft contact lens. Hence, it is possible to synthesize new nanophotonic soft contact lenses of desired optical characteristics, implying possibilities for their application in this field.

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

Science.gov (United States)

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.

[Effect of intraocular pressure measurement through therapeutic soft contact lenses by noncontact tonometer].

Science.gov (United States)

Sugimoto-Takeuchi, R; Yamamoto, R; Kuwayama, Y; Kinoshita, S

1991-09-01

The measurement of intraocular pressure (IOP) was compared with and without soft contact lenses by a non-contact tonometer. The soft contact lenses examined were Plano-T and Plano-B4 therapeutic contact lenses and Breath-O refractive lens. Twenty-nine eyes of 18 patients with an IOP ranging from 9 to 48mmHg were studied. The measurements of IOP were 19.7 +/- 8.6mmHg with Plano-T and 18.9 +/- 9.2mmHg with Plano-B4. Both numbers were not statistically different, when compared with controls (19.3 +/- 9.8mmHg without lens). There was, however, a significant difference significant difference with (44.7 +/- 10.7mmHg) and without the Breath-O (p less than 0.01). The results suggest that accurate IOP measurements can be obtained through therapeutic soft contact lens by a non-contact tonometer.

Polymer-interaction driven diffusionof eyeshadow in soft contact lenses.

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Tavazzi, Silvia; Rossi, Alessandra; Picarazzi, Sara; Ascagni, Miriam; Farris, Stefano; Borghesi, Alessandro

2017-10-01

Soft contact lenses used for the correction of ametropia are often made of hydrogel and silicone-hydrogel materials. Since they are placed directly on the surface of the eye and they are hydrated by tears, eye cosmetics can compromise the lens performance and, even worse, can be transported from an external environment to the ocular surface through the contact lens. The diffusion of the dye component of a purple eyeshadow in soft contact lenses of different materials is here evaluated. Diffusivity is found to be typically higher in silicone-hydrogels than in hydrogels. In hydrogels, diffusivity is greater in the case of lower oxygen transmissibility. Despite differences between materials, absorbed mass of dye is much larger (10-100 times) than the expected mass by simple hydration and swelling of the contact lens. The most contaminated materials are also resistant to cleaning solutions. The results indicate that, notwithstanding the complexity of contact lens networks, diffusion of dye is found to follow Fick's law and it is driven by polymer-dye interaction, which governs lens hydration and swelling. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Refractive surgery or contact lenses – how and when to decide?

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Xu K

2011-11-01

Full Text Available Kunyong Xu1, Vishal Jhanji2 1Michael G DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada; 2Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong Abstract: Correction of refractive errors can be achieved with spectacles, contact lenses, and refractive surgery. The past decade has seen a surge in the availability of alternatives for patients and surgeons in terms of both surgical and nonsurgical options for the management of refractive errors. Newer generation contact lenses provide enhanced safety and better handling, whereas modern-day refractive surgery presents a plethora of choices based on the clinical characteristics and requirements of patients. We have moved from an era of "one size fits all" to a purely customized way of treating patients with refractive errors. This review presents the background, advantages, and disadvantages of the two most commonly used options for correction of ametropia, ie, contact lenses and refractive surgery. Keywords: laser-assisted in situ keratomileusis, contact lens, patient selection, complications, outcomes

Physicochemical factors influencing bacterial transfer from contact lenses to surfaces with different roughness and wettability.

Science.gov (United States)

Vermeltfoort, Pit B J; van der Mei, Henny C; Busscher, Henk J; Hooymans, Johanna M M; Bruinsma, Gerda M

2004-11-15

The aim of this study was to determine the transfer of Pseudomonas aeruginosa No. 3 and Staphylococcus aureus 835 from contact lenses to surfaces with different hydrophobicity and roughness. Bacteria were allowed to adhere to contact lenses (Surevue, PureVision, or Focus Night & Day) by incubating the lenses in a bacterial suspension for 30 min. The contaminated lenses were put on a glass, poly(methylmethacrylate), or silicone rubber substratum, shaped to mimic the eye. After 2 and 16 h, lenses were separated from the substrata and bacteria were swabbed off from the respective surfaces and resuspended in saline. Appropriate serial dilutions of these suspensions were made, from which aliquots were plated on agar for enumeration. Bacterial transfer varied between 4 and 60%, depending on the combination of strain, contact time, contact lens, and substratum surface. For P. aeruginosa No. 3, transfer was significantly higher after 16 h than after 2 h, whereas less increase with time was seen for S. aureus 835. Bacterial transfer from all tested contact lenses was least to silicone rubber, the most hydrophobic and roughest substratum surface included. (c) 2004 Wiley Periodicals, Inc.

The Antibiofilm efficacy of nitric oxide on soft contact lenses.

Science.gov (United States)

Kim, Dong Ju; Park, Joo-Hee; Kim, Marth; Park, Choul Yong

2017-11-21

To investigate the antibiofilm efficacy of nitric oxide (NO) on soft contact lenses. Nitrite (NO precursor) release from various concentrations (0-1000 μM) of sodium nitrite (NaNO 2, NO donor) was measured by Griess Assay. Cell viability assay was performed using human corneal epithelial cell under various concentration (0-1000 μM) of NaNO 2 . Biofilm formation on soft contact lenses was achieved by adding Staphylococcus aureus or Pseudomonas aeruginosa to the culture media. Various concentrations of NaNO 2 (0-1000 μM) were added to the culture media, each containing soft contact lens. After incubation in NaNO 2 containing culture media for 1, 3, or 7 days, each contact lens was transferred to a fresh, bacteria-free media without NaNO 2 . The bacteria in the biofilm were dispersed in the culture media for planktonic growth. After reculturing the lenses in the fresh media for 24 h, optical density (OD) of media was measured at 600 nm and colony forming unit (CFU) was counted by spreading media on tryptic soy agar plate for additional 18 h. Nitrite release from NaNO 2 showed dose-dependent suppressive effect on biofilm formation. Most nitrite release from NaNO 2 tended to occur within 30 min. The viability of human corneal epithelial cells was well maintained at tested NaNO 2 concentrations. The bacterial CFU and OD showed dose-dependent decrease in the NaNO 2 treated samples on days 1, 3 and 7 for both Staphylococcus aureus and Pseudomonas aeruginosa. NO successfully inhibited the biofilm formation by Staphylococcus aureus or Pseudomonas aeruginosa on soft contact lenses in dose-dependent manner.

Adhesion of Stenotrophomonas maltophilia, Delftia acidovorans, and Achromobacter xylosoxidans to Contact Lenses.

Science.gov (United States)

Vijay, Ajay Kumar; Willcox, Mark D P

2017-09-26

Contact lens cases become contaminated with microbes during use. We wished to compare the adhesion of uncommon bacterial contaminants isolated from lens cases to contact lenses with and without organic soil. Strains of Delftia acidovorans (001), Stenotrophomonas maltophilia (002 and 006), and Achromobacter xylosoxidans (001) isolated from contact lens cases (test strains) and Pseudomonas aeruginosa (Paer1) isolated from eyes at the time of infiltrative response (control strain) were used. Bacteria were grown and resuspended in phosphate-buffered saline (PBS) or 10% organic soil (heat-killed Saccharomyces cerevisiae resuspended in complement inactivated bovine serum). Two silicone hydrogel (senofilcon A and comfilcon A) and one hydrogel lens (etafilcon A) lens materials were used. Bacteria (1.0×10 and 1.0×10 colony-forming units/mL; CFU/mL) adhered to lenses for 24 hr and the numbers of bacteria adherent to each lens type (with and without organic soil) were estimated by culture. All the four test strains adhered in significantly greater numbers to contact lenses after incubation in inoculum prepared with organic soil compared with PBS-D. acidovorans 001 (0.7 log10 CFU; P0.05). Achromobacter xylosoxidans 001 (PBacteria that are commonly found in contact lens cases adhered to contact lenses in relatively high numbers in the presence of organic soil. This might indicate that a similar phenomenon occurs in the presence of tears. This may facilitate their transfer from the lens to the cornea and the production of corneal infiltrates.

Evaluation of glutaraldehyde and povidone iodine for sterilization of wide-field contact vitrectomy lenses.

Science.gov (United States)

Das, T; Sharma, S; Singh, J; Rao, V; Chalam, K V

2001-01-01

Wide-field vitrectomy contact lenses are currently sterilized with ethylene oxide gas, and other lenses with autoclaving. To maintain a large inventory or possibly run the risk of loss of lens quality with repeated autoclaving, glutaraldehyde 2% and povidone iodine 5% solution were evaluated as possible sterilizing agents. Ethylene oxide presterilized lenses were contaminated with known concentrations (10(5) organisms/mL) of bacteria (S. epidemidis, P. aeruginosa, B. subtilis), and fungi (A. flavus, C. albicans) for 5 minutes. The test lenses were treated with glutaraldehyde or povidone iodine for 5, 10, 30, 60, and 120 minutes, and controls with sterilized water for a similar duration. Following treatment, both test and control lenses were sampled with sterile cotton swabs. The swabs were cultured for bacteria (tryptone soya broth 48 hours), and fungi (Saubourd's dextrose broth 5 days). The culture was negative for both glutaraldehyde- and povidone iodine-treated lenses against all organisms at all time points except B subtilis, which needed 120 minutes treatment. Two hours contact time with glutaraldehyde 2% or providone iodine 5% can sterilize vitrectomy contact lenses against common bacteria and fungi without affecting lens quality.

Comfort, Ocular Dryness, and Equilibrium Water Content Changes of Daily Disposable Contact Lenses.

Science.gov (United States)

Insua Pereira, Eduardo; Lira, Madalena

2017-10-26

The objective of this investigation was to evaluate the level of comfort and ocular dryness during wear with six daily disposable contact lenses (DDCL) and also determine the changes in contact lens equilibrium water content (EWC) resulting from their wear. In this contralateral open trial, 27 subjects were randomly fitted with six DDCL (stenfilcon A, delefilcon A, nelfilcon A, narafilcon A, nesofilcon A, and omafilcon A). The evaluation of comfort and ocular dryness sensation was recorded by the participants at two moments of the day (11 AM and 5 PM) over a period of 10 days of contact lens wear. The assessment was made with the aid of visual analogue scales (0-10). The refractive index of 54 contact lenses was accessed by a single operator using a digital automated refractometer (CLR 12-70; Index Instruments). The EWC of the lenses was estimated based on its refractive index values. Comfort ratings were slightly higher for delefilcon A (9.56±0.67, P=0.01) and narafilcon A (9.40±0.93, P=0.01) and these lenses wearers also reported less ocular dryness. The results revealed a pronounced water content reduction for omafilcon A (P=0.002), narafilcon A (P=0.008), and nesofilcon A (P=0.003). Although changes in subjective responses and EWC were distinct among the materials analyzed, all the contact lenses performed well during the 10 days of wear.

The effect of protein-coated contact lenses on the adhesion and viability of gram negative bacteria.

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Williams, Timothy J; Schneider, Rene P; Willcox, Mark D P

2003-10-01

Gram negative bacterial adhesion to contact lenses can cause adverse responses. During contact lens wear, components of the tear film adsorb to the contact lens. This study aimed to investigate the effect of this conditioning film on the viability of bacteria. Bacteria adhered to contact lenses which were either unworn, worn for daily-, extended- or overnight-wear or coated with lactoferrin or lysozyme. Numbers of viable and total cells were estimated. The number of viable attached cells was found to be significantly lower than the total number of cells on worn (50% for strain Paer1 on daily-wear lenses) or lactoferrin-coated lenses (56% for strain Paer1). Lysozyme-coated lenses no statistically significant effect on adhesion. The conditioning film gained through wear may not inhibit bacterial adhesion, but may act adversely upon those bacteria that succeed in attaching.

Adhesion of Pseudomonas aeruginosa and Staphylococcus epidermidis to silicone-hydrogel contact lenses.

Science.gov (United States)

Henriques, Mariana; Sousa, Cláudia; Lira, Madalena; Elisabete, M; Oliveira, Real; Oliveira, Rosário; Azeredo, Joana

2005-06-01

The purpose of this study is to compare the adhesion capabilities of the most important etiologic agents of microbial ocular infection to the recently available silicone-hydrogel lenses with those to a conventional hydrogel lens. In vitro static adhesion assays of Pseudomonas aeruginosa 10,145, Staphylococcus epidermidis 9142 (biofilm-positive), and 12,228 (biofilm-negative) to two extended-wear silicone-hydrogel lenses (balafilcon A and lotrafilcon A), a daily wear silicone-hydrogel lens (galyfilcon A) and a conventional hydrogel (etafilcon A) were performed. To interpret the adhesion results, lens surface relative hydrophobicity was assessed by water contact angle measurements. P. aeruginosa and S. epidermidis 9142 exhibited greater adhesion capabilities to the extended wear silicone-hydrogel lenses than to the daily wear silicone- and conventional hydrogel lenses (p adhesion extent of these strains to galyfilcon A and etafilcon A. The biofilm negative strain of S. epidermidis adhered in larger extents to the silicone-hydrogel lenses than to the conventional hydrogel (p contact angle measurements revealed that the extended wear silicone-hydrogel lenses are hydrophobic, whereas the daily wear silicone- and conventional hydrogel lenses are hydrophilic. As a result of their hydrophobicity, the extended wear silicone-hydrogel lenses (lotrafilcon A and balafilcon A) may carry higher risk of microbial contamination than both the hydrophilic daily wear silicone-hydrogel lens, galyfilcon A and the conventional hydrogel lens, etafilcon A.

Prevention of bacterial colonization of contact lenses with covalently attached selenium and effects on the rabbit cornea.

Science.gov (United States)

Mathews, Steven M; Spallholz, Julian E; Grimson, Mark J; Dubielzig, Richard R; Gray, Tracy; Reid, Ted W

2006-08-01

Although silicone hydrogel materials have produced many corneal health benefits to patients wearing contact lenses, bacteria that cause acute red eye or corneal ulcers are still a concern. A coating that inhibits bacterial colonization while not adversely affecting the cornea should improve the safety of contact lens wear. A covalent selenium (Se) coating on contact lenses was evaluated for safety using rabbits and prevention of bacterial colonization of the contact lenses in vitro. Contact lenses coated with Se were worn on an extended-wear schedule for up to 2 months by 10 New Zealand White rabbits. Corneal health was evaluated with slit-lamp biomicroscopy, pachymetry, electron microscopy, and histology. Lenses worn by the rabbits were analyzed for protein and lipid deposits. In addition, the ability of Se to block bacterial colonization was tested in vitro by incubating lenses in a Pseudomonas aeruginosa broth followed by scanning electron microscopy of the contact lens surface. The covalent Se coating decreased bacterial colonization in vitro while not adversely affecting the corneal health of rabbits in vivo. The Se coating produced no noticeable negative effects as observed with slit-lamp biomicroscopy, pachymetry, electron microscopy, and histology. The Se coating did not affect protein or lipid deposition on the contact lenses. The data from this pilot study suggest that a Se coating on contact lenses might reduce acute red eye and bacterial ulceration because of an inhibition of bacterial colonization. In addition, our safety tests suggest that this positive effect can be produced without an adverse effect on corneal health.

Influence of protein deposition on bacterial adhesion to contact lenses.

Science.gov (United States)

Subbaraman, Lakshman N; Borazjani, Roya; Zhu, Hua; Zhao, Zhenjun; Jones, Lyndon; Willcox, Mark D P

2011-08-01

The aim of the study is to determine the adhesion of Gram positive and Gram negative bacteria onto conventional hydrogel (CH) and silicone hydrogel (SH) contact lens materials with and without lysozyme, lactoferrin, and albumin coating. Four lens types (three SH-balafilcon A, lotrafilcon B, and senofilcon A; one CH-etafilcon A) were coated with lysozyme, lactoferrin, or albumin (uncoated lenses acted as controls) and then incubated in Staphylococcus aureus (Saur 31) or either of two strains of Pseudomonas aeruginosa (Paer 6294 and 6206) for 24 h at 37 °C. The total counts of the adhered bacteria were determined using the H-thymidine method and viable counts by counting the number of colony-forming units on agar media. All three strains adhered significantly lower to uncoated etafilcon A lenses compared with uncoated SH lenses (p 0.05). Lactoferrin coating on lenses increased binding (total and viable counts) of Saur 31 (p lenses showed significantly higher total counts (p lenses. Albumin coating of lenses increased binding (total and viable counts) of all three strains (p lenses does not possess antibacterial activity against certain bacterial strains, whereas lactoferrin possess an antibacterial effect against strains of P. aeruginosa.

Effect of surfactant chain length on drug release kinetics from microemulsion-laden contact lenses.

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Maulvi, Furqan A; Desai, Ankita R; Choksi, Harsh H; Patil, Rahul J; Ranch, Ketan M; Vyas, Bhavin A; Shah, Dinesh O

2017-05-30

The effect of surfactant chain lengths [sodium caprylate (C 8 ), Tween 20 (C 12 ), Tween 80 (C 18 )] and the molecular weight of block copolymers [Pluronic F68 and Pluronic F 127] were studied to determine the stability of the microemulsion and its effect on release kinetics from cyclosporine-loaded microemulsion-laden hydrogel contact lenses in this work. Globule size and dilution tests (transmittance) suggested that the stability of the microemulsion increases with increase in the carbon chain lengths of surfactants and the molecular weight of pluronics. The optical transmittance of direct drug-laden contact lenses [DL-100] was low due to the precipitation of hydrophobic drugs in the lenses, while in microemulsion-laden lenses, the transmittance was improved when stability of the microemulsion was achieved. The results of in vitro release kinetics revealed that drug release was sustained to a greater extent as the stability of microemulsion was improved as well. This was evident in batch PF127-T80, which showed sustained release for 15days in comparison to batch DL-100, which showed release up to 7days. An in vivo drug release study in rabbit tear fluid showed significant increase in mean residence time (MRT) and area under curve (AUC) with PF-127-T80 lenses (stable microemulsion) in comparison to PF-68-SC lenses (unstable microemulsion) and DL-100 lenses. This study revealed the correlation between the stability of microemulsion and the release kinetics of drugs from contact lenses. Thus, it was inferred that the stable microemulsion batches sustained the release of hydrophobic drugs, such as cyclosporine from contact lenses for an extended period of time without altering critical lens properties. Copyright © 2017 Elsevier B.V. All rights reserved.

pH triggered controlled drug delivery from contact lenses: Addressing the challenges of drug leaching during sterilization and storage.

Science.gov (United States)

Maulvi, Furqan A; Choksi, Harsh H; Desai, Ankita R; Patel, Akanksha S; Ranch, Ketan M; Vyas, Bhavin A; Shah, Dinesh O

2017-09-01

In the present work a novel cyclosporine-loaded Eudragit S100 (pH-sensitive) nanoparticles-laden contact lenses were designed to provide sustained release of cyclosporine at therapeutic rates, without leaching of drug during sterilization and storage period (shelf life). The nanoparticles were prepared by Quasi-emulsion solvent diffusion technique using different weight ratios of cyclosporine to Eudragit S100. The contact lenses with direct drug entrapment were also fabricated (DL-50) for comparison. The percentage swelling and optical transparency of nanoparticles-laden contact lenses were improved in comparison to DL-50 lenses. The nanoparticles-laden contact lenses showed sustained drug release profiles, with inverse relationship to the amount of nanoparticles loaded in the contact lenses. It was interesting to note that nanoparticles form nanochannels/cavities after dissolution of Eudragit S 100 in tear fluid pH=7.4 (in vitro release study). This followed the precipitation of drug in hydrogel matrix of contact lenses. As the amount of nanoparticles loading increased, more number of cavities were formed, which caused the formation of large cavities in contact lens matrix. This in turn precipitated the drug. The nanoparticles-laden contact lenses with 1:1 (drug: Eudragit) weight ratio showed the most promising results of sustaining the drug release up to 156h, without affecting optical and physical properties of contact lenses. Packaging study confirmed that the drug was not leached in packaging solution (buffer, pH=6.5) from nanoparticles-laden lenses during shelf life period. In-vivo study in rabbit tear fluid showed sustained release up to 14days. The study revealed the application of pH-sensitive nanoparticles-laden contact lenses for controlled release of cyclosporine without altering the optical and physical properties of lens material. Copyright © 2017 Elsevier B.V. All rights reserved.

Oxygen permeability of the pigmented material used in cosmetic daily disposable contact lenses

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Galas S

2016-12-01

Full Text Available Stephen Galas, Lenora L Copper Johnson & Johnson Vision Care Inc., Jacksonville, FL, USA Purpose: To evaluate the individual contributions of pigment colorant and packing solution containing polyvinyl pyrrolidone (PVP on the oxygen permeability (Dk of a cosmetic printed etafilcon A daily disposable contact lens packaged with PVP. Method: The oxygen transport of a contact lens is evaluated through the central optical zone of the lens. Cosmetic printed contact lenses contain pigment colorant in the periphery or mid-periphery of the lens. Therefore, to assess the impact of cosmetic print on oxygen permeability, special lenses need to be produced that contain the colorant within the central optical zone. This technique was used to obtain multiple measurements of nonedge-corrected Dk/t of both the center pigmented lens and its nonpigmented equivalent, using a polarographic measurement described in International Organization for Standardization (ISO 18369-4:2006(E, and the Dk derived for each measurement is corrected for edge effect. In addition, the edge-corrected Dk values of lenses made from the same monomer batch were measured. The lenses were packaged and autoclaved with and without proprietary technology which embeds PVP in the contact lens during autoclaving. The resulting Dk value of the printed lens material was then used with thickness data to generate true Dk/t profiles for a given lens power. Results: The edge-corrected Dk of the printed etafilcon A lens with offset pigment colorant was measured to be 19.7×10-11 (cm2/s (mL O2/mL·mmHg at 35°C. This was within ±20% tolerance range as specified in ISO 18369-2:2012(E for the edge-corrected Dk of the nonpigmented etafilcon A control lens evaluated during the same session, 19.5×10-11 (cm2/s (mL O2/mL·mmHg. The edge-corrected Dk values of the lenses packaged with PVP (mean 20.1, standard deviation [SD] 0.3 were also within the ±20% tolerance range compared to those packaged without PVP

Adhesion of Pseudomonas aeruginosa to contact lenses after exposure to multi-purpose lens care solutions

NARCIS (Netherlands)

Bruinsma, GM; Van der Mei, HC; Busscher, HJ; de Vries, Jacob

2001-01-01

Elemental surface compositions of contact lenses were measured after exposure to different lens care solutions (LCS) using X-ray photoelectron spectroscopy and were related to adhesion and detachment of Pseudomonas aeruginosa. Etafilcon A and polymacon contact lenses, prior to and after exposure to

Physicochernical factors influencing bacterial transfer from contact lenses to surfaces with different roughness and Wettability

NARCIS (Netherlands)

Vermeltfoort, PBJ; van der Mei, HC; Busscher, HJ; Hooymans, JMM; Bruinsma, GM

2004-01-01

The aim of this study was to determine the transfer of Pseudomonas aeruginosa No. 3 and Staphylococcus aureus 835 from contact lenses to surfaces with different hydrophobicity and roughness. Bacteria were allowed to adhere to contact lenses (Surevue, PureVision, or Focus Night & Day) by incubating

A study of the suitability of disposable coloured contact lenses for a South African clinic based population

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V. R. Moodley

2009-12-01

Full Text Available Optomet rists have always considered the fitting of all types of contact lenses to be an integral part of the scope of practice of their profession.  However, since the introduction of disposable cosmetic coloured contact lenses into the market, the frequency of over the counter sales of contact lenses has significantly increased.  Patients often present with contact lens complications at the University of Kwa-Zulu Natal clinic and local practices.  It is sometimes reported that the lenses were purchased over the counter, from an optometry practice or another non-registered vendor.  A common observation in these instances has been that the lenses do not fit optimally and that the incidence of complications associated with tight fitting lenses was much higher amongst the African patients as opposed to those of other race groups.  A clinical observational study utilizing convenience sampling of 240 subjects was undertaken to evaluate the fitting criteria of disposable cosmetic coloured contact lenses on a South African clinic based population.  All patients requesting the lenses chose their preferred colour and were fitted with Freshlook ColorBlends, Images or Expressions Colors lenses.  Lenses were evaluated after 20-25 minutes and then classified into tight, ideal or loose fits according to the lower lid push-up test, lenscentration, post blink movement and version lag and upgaze lens movements.  The ages of the subjects ranged from 16 to 45 years with a mean of 24.13 ± 5.66 years.  Seventy (29.2% were males and 170 (70.8% were females. The majority (62.9% of the lenses fitted on the subjects were rejected according to the fit criteria. The African subjects had the highest percentage of rejected fits (82.8% whilst 75% of the White subjects had acceptable fits.  The main reason for lens fits being rejected was that they displayed charac teristics of a tight fit (96% with only 4% of the fits being rejected due to being too loose. These

Intraocular pressure measurement with the noncontact tonometer through soft contact lenses.

Science.gov (United States)

Liu, Yi-Chun; Huang, Jehn-Yu; Wang, I-Jong; Hu, Fung-Rong; Hou, Yu-Chih

2011-03-01

To assess the accuracy of measuring intraocular pressure (IOP) through a soft contact lens (SCL) with different refractive powers using a noncontact tonometer (NCT). Thirty-two healthy adult volunteers free of glaucoma or corneal disease participated in this study. IOP was measured in the right eyes without SCLs and with different lens powers, from -3.0 to -12.0 D as measured by NCT. IOP of the left eyes was also measured, as an internal control. Corneal curvature was measured in both eyes using an autokeratometer. Sixteen volunteers wore one brand of SCL (group A) and the other 16 wore a different brand, with 2 different curvatures (groups B and C). Statistical data were analyzed by SPSS using the Wilcoxon signed rank test for comparison of IOP readings and multiple linear regression analysis for the relationship among power of contact lenses, corneal power, and difference in IOP measurements. The difference in mean IOP between eyes without lenses and those with lenses was statistically significant in lens with -6.0 D and below in all 3 groups. The decrease in IOP significantly correlated with the refractive power of contact lenses in all 3 groups. The difference in IOP measurements was influenced by the mean K in group A but not in group B or C. There was no statistically significant difference in the IOP measurements in the left eyes or in the mean K between the right and left eyes. IOP measurement through myopic SCLs by NCT may be inaccurate and tends toward underestimation, especially in high myopic lenses. A strong relationship exists between IOP reduction and myopic lens power.

[Profile of medical students from the Universidade Estadual Paulista-UNESP--Botucatu, who wear contact lenses].

Science.gov (United States)

Vidotti, Vanessa Gonçalves; Kamegasawa, Amélia

2006-01-01

To analyze the ametropy, way of acquisition, the care and complications related to contact lens wear among medical students from Faculdade de Medicina de Botucatu da Universidade Estadual Paulista-UNESP--Botucatu (SP). Questionnaire applied to students from the 1st to the 6th year of the Medical school of the Faculdade de Medicina de Botucatu da Universidade Estadual Paulista-UNESP--Botucatu (SP), forming an analytical cross-sectional survey. 27.4% of the students use contact lenses, and among them 94.8% use soft contact lenses and 98% have negative degree. 46.9% discard their contact lens monthly. 63.9% have an average daily use of 14 hours, 14.1% acquire the contact lenses from optician stores or at pharmacies and 46.5% of the students clean their contact lenses when they put them on and take them off. Regarding complications, 51.0% reported ocular redness; 44.5%, blurred vision; and 42.6%, foreign body sensation, whereas only 4 students reported "keratitis". We concluded that the inadequate adaptation that occurs even in users knowledgeable about this issue such as medical students, has increased the risk of complications. This fact indicates that more attention must be paid to contact lens care in order to prevent permanent visual deficit.

Microbial changes in conjunctival flora with 30-day continuous-wear silicone hydrogel contact lenses.

Science.gov (United States)

Iskeleli, Güzin; Bahar, Hrisi; Eroglu, Ebru; Torun, Muzeyyen Mamal; Ozkan, Sehirbay

2005-05-01

To determine the effect of 30-day continuous-wear silicone hydrogel contact lenses on the conjunctival flora in asymptomatic wearers. The authors studied 29 eyes of 15 patients wearing Focus NIGHT & DAY silicone hydrogel contact lenses for up to 30 nights of continuous wear. The average age of the patients was 25.54 +/- 8.98 years. Cultures of the inferior cul-de-sac were taken bilaterally from all eyes, before and after lens wear in asymptomatic patients. The isolation and identification of bacteria were made by standard clinical laboratory methods. The number of eyes whose conjunctival cultures were sterile before using the lenses significantly decreased (P = 0.0005), and the number of eyes with a growth of coagulase-negative staphylococci and diphtheroid rods in their conjunctival cultures significantly increased after using these lenses (P = 0.001 and P = 0.031, respectively). Conversely, a statistically significant difference was not found in the number of eyes that carried Propionibacterium acnes and Fusobacterium nucleatum in their conjunctival cultures before and after using the 30-day continuous-wear silicone hydrogel lenses (P = 0.998 and P = 0.488, respectively). The results suggest that the sterility of the conjunctiva significantly decreased after using 30-day continuous-wear silicone hydrogel contact lenses. In addition, the number of bacteria of the normal conjunctival flora significantly increased after the use of these lenses. Contamination by the bacteria of the eyelids may be a possible colonization factor in this study group. Therefore, it is appropriate to examine the patients who wear these lenses more frequently.

The use of contact lenses in low vision rehabilitation: optical and therapeutic applications.

Science.gov (United States)

Vincent, Stephen J

2017-09-01

Ocular pathology that manifests at an early age has the potential to alter the vision-dependent emmetropisation mechanism, which co-ordinates ocular growth throughout childhood. The disruption of this feedback mechanism in children with congenital or early-onset visual impairment often results in the development of significant ametropia, including high levels of spherical refractive error, astigmatism and anisometropia. This review examines the use of contact lenses as a refractive correction, low vision aid and therapeutic intervention in the rehabilitation of patients with bilateral, irreversible visual loss due to congenital ocular disease. The advantages and disadvantages of the use of contact lenses for increased magnification (telescopes and microscopes) or field expansion (reverse telescopes) are discussed, along with the benefits and practical considerations for the correction of pathological high myopia. The historical and present use of therapeutic tinted contact lenses to reduce photosensitivity and nystagmus in achromatopsia, albinism and aniridia are also presented, including clinical considerations for the contact lens practitioner. In addition to the known optical benefits in comparison to spectacles for high levels of ametropia (an improved field of view for myopes and fewer inherent oblique aberrations), contact lenses may be of significant psycho-social benefit for patients with low vision, due to enhanced cosmesis and reduced conspicuity and potential related effects of improved self-esteem and peer acceptance. The contact lens correction of patients with congenital vision impairment can be challenging for both practitioner and patient but should be considered as a potential optical or therapeutic solution in modern low vision rehabilitation. © 2017 Optometry Australia.

Visual performance with sport-tinted contact lenses in natural sunlight.

Science.gov (United States)

Erickson, Graham B; Horn, Fraser C; Barney, Tyler; Pexton, Brett; Baird, Richard Y

2009-05-01

The use of tinted and clear contact lenses (CLs) in all aspects of life is becoming a more popular occurrence, particularly in athletic activities. This study broadens previous research regarding performance-tinted CLs and their effects on measures of visual performance. Thirty-three subjects (14 male, 19 female) were fitted with clear B&L Optima 38, 50% visible light transmission Amber and 36% visible light transmission Gray-Green Nike Maxsight CLs in an individualized randomized sequence. Subjects were dark-adapted with welding goggles before testing and in between subtests involving a Bailey-Lovie chart and the Haynes Distance Rock test. The sequence of testing was repeated for each lens modality. The Amber and Gray-Green lenses enabled subjects to recover vision faster in bright sunlight compared with clear lenses. Also, subjects were able to achieve better visual recognition in bright sunlight when compared with clear lenses. Additionally, the lenses allowed the subjects to alternate fixation between a bright and shaded target at a more rapid rate in bright sunlight as compared with clear lenses. Subjects preferred both the Amber and Gray-Green lenses over clear lenses in the bright and shadowed target conditions. The results of the current study show that Maxsight Amber and Gray-Green lenses provide better contrast discrimination in bright sunlight, better contrast discrimination when alternating between bright and shaded target conditions, better speed of visual recovery in bright sunlight, and better overall visual performance in bright and shaded target conditions compared with clear lenses.

Descriptive analysis of the type and design of contact lenses fitted according to keratoconus severity and morphology

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Letícia Helena Lunardi

2016-04-01

Full Text Available ABSTRACT Purpose: Keratoconus is characterized by bilateral asymmetrical corneal ectasia that leads to inferior stromal thinning and corneal protrusion. There is currently a lack of consensus regarding the most efficacious method for fitting contact lenses in patients with keratoconus, given the various topographical patterns and evolution grades observed in affected populations. The purpose of the present study was to evaluate the association between keratoconus evolution grade and topography pattern and the type and design of fitted contact lens. Methods: We performed a retrospective analysis of contact lenses fitted in a total of 185 patients with keratoconus (325 eyes. Keratoconus was classified as either grade I, II, III, or IV based on keratometry and cone morphology (nipple, oval, globus, or indeterminate results. Results: A total of 325 eyes were evaluated in the present study. Of the 62 eyes classified as grade I, 66.1% were fitted with monocurve contact lenses. Of the 162 eyes classified as grade I and II, 51%, 30%, and 19% were fitted with adapted monocurve rigid gas-permeable contact lenses (RGPCL, bicurve lenses, and others lens types, respectively. Bicurve lenses were fitted in 52.1% and 62.2% of eyes classified as grade III and IV, respectively. Of the eyes classified as grade III and IV, monocurve and bicurve RGPCL were fitted in 26% and 55%, respectively. In eyes with oval keratoconus, 45%, 35%, and 20% were fitted with monocurve lenses, bicurve lenses, and other lens types, respectively. In eyes with round cones (nipple morphology, 55%, 30%, and 15% were fitted with bicurve lenses, monocurve lenses, and other lens types, respectively. Conclusion: Monocurve RGPCL were most frequently fitted in patients with mild to moderate keratoconus and oval cones morphology, while bicurve lenses were more frequently fitted in patients with severe and advanced keratoconus. This was probably because bicurve lenses are more appropriate for

External ocular surface and lens microbiota in contact lens wearers with corneal infiltrates during extended wear of hydrogel lenses.

Science.gov (United States)

Willcox, Mark; Sharma, Savitri; Naduvilath, Thomas J; Sankaridurg, Padmaja R; Gopinathan, Usha; Holden, Brien A

2011-03-01

To determine whether carriage of microbes on the contact lens or ocular surfaces during extended wear (EW) with soft hydroxyethyl methacrylate (HEMA)-based contact lenses predisposes the wearer to adverse events. Participants (non-contact lens wearers) were enrolled in a clinical study involving wear of HEMA-based hydrogel lenses on a six night EW basis with weekly replacement. Type and number of bacteria colonizing the lower lid margins, upper bulbar conjunctiva, and contact lenses during EW after one night, 1 week, 1 month, and thereafter every 3 months for 3.5 years were determined. The association of bacteria with adverse responses was compared between carriers (defined as having significant microbes cultured from two or more samples with 1 year) and noncarriers, and the strength of the association was estimated using multivariate logistic regression. Carriers of gram-positive bacteria on lenses (particularly coagulase negative staphylococci or Corynebacterium spp.) were approximately three and eight times more likely to develop contact lens-induced peripheral ulcers (CLPUs) and asymptomatic infiltrates (AIs), respectively. Staphylococcus aureus was most frequently isolated from lenses during CLPU. Carriers of gram-negative bacteria on lenses were five times more likely to develop contact lens-induced acute red eye (CLARE). Haemophilus influenzae was isolated most frequently from lenses during CLARE and AI events. Bacterial carriage on contact lenses during EW predisposes the wearer to the development of corneal inflammatory events including CLARE, CLPU, and AI.

In vivo performance of melimine as an antimicrobial coating for contact lenses in models of CLARE and CLPU.

Science.gov (United States)

Cole, Nerida; Hume, Emma B H; Vijay, Ajay K; Sankaridurg, Padmaja; Kumar, Naresh; Willcox, Mark D P

2010-01-01

One strategy to minimize bacteria-associated adverse responses such as microbial keratitis, contact lens-induced acute red eye (CLARE), and contact lens induced peripheral ulcers (CLPUs) that occur with contact lens wear is the development of an antimicrobial or antiadhesive contact lens. Cationic peptides represent a novel approach for the development of antimicrobial lenses. A novel cationic peptide, melimine, was covalently incorporated into silicone hydrogel lenses. Confirmation tests to determine the presence of peptide and anti-microbial activity were performed. Cationic lenses were then tested for their ability to prevent CLPU in the Staphylococcus aureus rabbit model and CLARE in the Pseudomonas aeruginosa guinea pig model. In the rabbit model of CLPU, melimine-coated lenses resulted in significant reductions in ocular symptom scores and in the extent of corneal infiltration (P lenses in the CLARE model showed significant improvement in all ocular response parameters measured, including the percentage of eyes with corneal infiltrates, compared with those observed in the eyes fitted with the control lens (P lenses with the peptide melimine may represent a novel method of prevention of bacterial growth on contact lenses and consequently result in reduction of the incidence and severity of adverse responses due to Gram-positive and -negative bacteria during lens wear.

Trends in the use of silicone hydrogel contact lenses for daily wear.

Science.gov (United States)

Efron, Nathan; Morgan, Philip B

2008-10-01

Although the first silicone hydrogel contact lenses introduced onto the world contact lens market in 1999 held approval for both daily wear and extended wear use, the latter modality was promoted much more heavily by the manufacturers. The first silicone hydrogel lenses specifically promoted for daily wear were introduced in 2003. Data that we have gathered from annual contact lens fitting surveys demonstrate an immediate increase in market share whereby this lens type now represents more than one-third of soft lens fits in the United Kingdom. The success of this lens category is attributed to the health and safety benefits of silicone hydrogel materials and the positive impact of lens manufacturers by way of the effective marketing and distribution of these products.

Bacterial and fungal biofilm formation on contact lenses and their susceptibility to lens care solutions

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Siddharth Kackar

2017-01-01

Full Text Available Background: Microbial biofilm formation on contact lenses and lens storage cases may be a risk factor for contact lens-associated corneal infections. Various types of contact lens care solutions are used to reduce microbial growths on lenses. Objectives: The present study aimed at comparing the growths of biofilms on the different contact lenses and lens cases. The study also aimed at determining the effect of lens care solutions and bacteriophage on these biofilms. Materials and Methods: One type of hard lens and two types of soft lenses were used for the study. The organisms used were Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Candida albicans ATCC 60193 and Escherichia coli ATCC 25922. Biofilm production was performed by modified O'Toole and Kolter method and effect of lens cleaning solutions and a crude coliphage on biofilms was also studied. Results were visualised using scanning electron microscopy and quantitated by colony counting method and spectrophotometric measurement of optical density (OD. Statistical analysis was done by SPSS 11.5, Kruskal–Wallis test and Chi-square test. Results: Soft lens cleaning solutions had a significant inhibitory effect (P = 0.020 on biofilm formation on soft lenses and also lens cases (P < 0.001. Soft lens cleaning solution 2 was more efficient than solution 1. However, no such inhibitory effect was observed with regard to hard lens cleaning solution, but for a significant reduction in the OD values (P < 0.001. There was no significant inhibitory effect by bacteriophages. Conclusion: This study showed the importance of selecting the appropriate lens cleaning solution to prevent biofilm production on contact lenses.

Phosphorylcholine impairs susceptibility to biofilm formation of hydrogel contact lenses.

Science.gov (United States)

Selan, Laura; Palma, Stefano; Scoarughi, Gian Luca; Papa, Rosanna; Veeh, Richard; Di Clemente, Daniele; Artini, Marco

2009-01-01

To compare silicone-hydrogel, poly(2-hydroxyethyl methacrylate) (pHEMA), and phosphorylcholine-coated (PC-C) contact lenses in terms of their susceptibility to biofilm formation by Staphylococcus epidermidis and Pseudomonas aeruginosa. Laboratory investigation. Biofilm formation on colonized test lenses was evaluated with confocal microscopy and in vitro antibiotic susceptibility assays. The results of the latter assays were compared with those performed on planktonic cultures of the same organism. For both microorganisms, sessile colonies on silicone-hydrogel and pHEMA lenses displayed lower antibiotic susceptibility than their planktonic counterparts. In contrast, the susceptibility of cultures growing on PC-C lenses was comparable with that for planktonic cultures. In particular, minimum inhibitory concentration for Tazocin (piperacillin plus tazobactam; Wyeth Pharmaceuticals, Aprilia, Italy; S. epidermidis) and gentamicin (P. aeruginosa) was identical, either in the presence of PC-C support or in planktonic cultures (Tazocin, aeruginosa) was two-fold higher for PC-C lenses (0.4 mug/ml) with respect to planktonic cultures (0.2 mug/ml). Confocal microscopy of lenses colonized for 24 hours with P. aeruginosa green fluorescent protein-expressing cells revealed a sessile colonization on silicone-hydrogel lens and a few isolated bacterial cells scattered widely over the surface of the PC-C lens. An increase in antibiotic susceptibility of bacterial cultures was associated with diminished bacterial adhesion. Our results indicate that PC-C lenses seem to be more resistant than silicone-hydrogel and pHEMA lenses to bacterial adhesion and colonization. This feature may facilitate their disinfection.

'Colored' and Decorative Contact Lenses: A Prescription Is a Must

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... Safely Wear Decorative or “Colored” Contact Lenses An entertainment industry artist from American Horror Story and the ... Follow FDA on Facebook View FDA videos on YouTube View FDA photos on Flickr FDA Archive Combination ...

A meta-analysis of studies on cosmetically tinted soft contact lenses

Directory of Open Access Journals (Sweden)

Rah MJ

2013-10-01

Full Text Available Marjorie J Rah,1 Jeffery Schafer,1 Lening Zhang,1 Osbert Chan,2 Lipika Roy,3 Joseph T Barr11Bausch & Lomb Incorporated, Rochester, NY, USA; 2Bausch & Lomb Incorporated, Asia Pacific Medical Affairs, Hong Kong; 3Bausch & Lomb Incorporated, Asia Pacific Medical Affairs, Singapore, MalaysiaBackground: Concerns regarding the safety of cosmetically tinted contact lenses have been reported in the literature. The purpose of this paper is to evaluate the safety of cosmetically tinted contact lenses in a large number of patients across six clinical trials that varied from 1 week to 3 months in duration.Methods: Lenses tested included: Naturelle limbal ring daily disposable, Lacelle limbal ring daily disposable, Lacelle colored cosmetic daily disposable, Lacelle limbal ring planned replacement at 2 weeks, and Alamode traditional/annual colored cosmetic lens. The primary safety outcome was slit-lamp examination, including epithelial edema, epithelial microcysts, corneal staining, bulbar injection, limbal injection, upper lid tarsal conjunctival abnormalities, corneal neovascularization, and corneal infiltrates. High contrast logMAR visual acuity with lenses, and lens wearing time, movement, and centration, are also presented.Results: A total of 871 subjects (1,742 eyes and 23 clinical investigators participated in the six studies, with an average completion rate of 96.4% across all studies. The mean age of the patients was 26.8 ± 6.6 years, and 86.7% of participants were female. The total number of slit-lamp examinations across the six studies was 2,456 visits by eye (1,228 visits by patient. There were no slit-lamp signs > grade 2 for any finding, with the exception of corneal staining in one study. In this study, grade 3 corneal staining was noted in one eye (0.1% at follow-up visit 1 and four (0.6% of all eligible dispensed eyes at follow-up visit 2, with no eyes requiring medical treatment. No adverse events were reported during any of the trials

Platelet lysate and chondroitin sulfate loaded contact lenses to heal corneal lesions.

Science.gov (United States)

Sandri, Giuseppina; Bonferoni, Maria Cristina; Rossi, Silvia; Delfino, Alessio; Riva, Federica; Icaro Cornaglia, Antonia; Marrubini, Giorgio; Musitelli, Giorgio; Del Fante, Claudia; Perotti, Cesare; Caramella, Carla; Ferrari, Franca

2016-07-25

Hemoderivative tear substitutes contain various ephiteliotrophic factors, such as growth factors (GF), involved in ocular surface homeostasis without immunogenic properties. The aim of the present work was the loading of platelet lysate into contact lenses to improve the precorneal permanence of platelet lysate growth factors on the ocular surface to enhance the treatment of corneal lesions. To this purpose, chondroitin sulfate, a sulfated glycosaminoglycan, which is normally present in the extracellular matrix, was associated with platelet lysate. In fact, chondroitin sulfate is capable of electrostatic interaction with positively charged growth factors, in particular, with bFGF, IGF, VEGF, PDGF and TGF-β, resulting in their stabilization and reduced degradation in solution. In the present work, various types of commercially available contact lenses have been loaded with chondroitin sulfate or chondroitin sulfate in association with platelet lysate to achieve a release of growth factors directly onto the corneal surface lesions. One type of contact lenses (PureVision(®)) showed in vitro good proliferation properties towards corneal cells and were able to enhance cut closure in cornea constructs. Copyright © 2016 Elsevier B.V. All rights reserved.

Demodex sp. as a Potential Cause of the Abandonment of Soft Contact Lenses by Their Existing Users

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Witold Tarkowski

2015-01-01

Full Text Available Demodex mites may be a potential etiological factor in the development of various eye and skin disorders. The aim of the study was to investigate the presence of Demodex in the hair follicles of eyelashes and their potential influence on abandoning soft contact lenses which had been previously well tolerated by their users. A group of 62 users of contact lenses (28 with emerging discomfort and 34 without discomfort were examined. There is a need to check the existence of a relationship between D. folliculorum or/and D. brevis infestation and the emergence of intolerance to the presence of soft contact lenses. The removed lashes were examined under light microscopy, applying standard parasitological methods if demodicosis is suspected. A positive result was assumed if at least one adult stage, larva, protonymph/nymph, or egg of D. folliculorum and/or D. brevis was present. A positive correlation was observed between the presence of Demodex and intolerance to contact lenses by their existing users p<0.05, and Demodex sp. infections were observed in 92.86% of patients with intolerance to contact lenses. Our results provide further evidence for the pathogenic role played by the mites in the development of eye diseases.

The measurement of intraocular pressure over positive soft contact lenses by rebound tonometry

Directory of Open Access Journals (Sweden)

Fabrizio Zeri

2016-07-01

Conclusions: Rebound tonometry over positive hydrogel CLs leads to a certain degree of IOP underestimation. This result did not change for the two positive lenses used in the experiment, despite their large difference in power and therefore in lens thickness. Optometrists should bear this in mind when measuring IOP with the rebound tonometer over plus power contact lenses.

Bacterial Colonization of Disposable Soft Contact Lenses Is Greater during Corneal Infiltrative Events than during Asymptomatic Extended Lens Wear

OpenAIRE

Sankaridurg, Padmaja R.; Sharma, Savitri; Willcox, Mark; Naduvilath, Thomas J.; Sweeney, Deborah F.; Holden, Brien A.; Rao, Gullapalli N.

2000-01-01

Microorganisms, especially gram-negative bacteria, are considered to play a role in the etiology of certain corneal infiltrative events (CIEs) observed during soft contact lens wear. This study explored the possibility of microbial colonization of soft contact lenses as a risk factor leading to CIEs. In a clinical trial conducted from March 1993 to January 1996, 330 subjects wore disposable soft contact lenses on a 6-night extended-wear and disposal schedule. During this period, 4,321 lenses ...

Reduction in ionic permeability of a silicone hydrogel contact lenses after one month of daily wear

International Nuclear Information System (INIS)

Ferreira da Silva, Ana Rita; González-Méijome, José M; Compañ, Vicente

2015-01-01

Purpose. To compare the ionic permeability using the ionoflux method of new and worn samples of a silicone hydrogel contact lens material. Methods. An ionoflux experimental setup was established to measure the ionic permeability (NaCl) of soft contact lenses. Samples of a silicone hydrogel lens (Comfilcon A, Coopervision, Pleasanton, CA) with optical powers of −1.00, −1.50 and −4.75 diopters (D) were used in this study. Three samples of each power were measured after being worn for one month on a daily wear basis. Lenses were cleaned and disinfected every night using multipurpose disinfecting solutions. Three samples of new lenses from the same batch and the same optical power were also measured to evaluate the effect of lens wear on the ionic permeability of the lens material. Before measurement, the lenses were equilibrated with a 1 M NaCl solution during one week before of each measurement. Results. Lens power had minimal effect on the ionic permeability of a modern silicone hydrogel contact lens with the −1.00 lens having a 15% lower permeability compared to the other two lenses. After one month of lens wear the apparent ionic permeability for lenses with −1.50 D decreased by 15%. In the case of −1.00 and −4.75 D lenses there was a decrease of 26%. Conclusions. The ionic permeability of silicone hydrogel lenses of different optical powers was not significantly different. Worn lenses present a significant reduction of the ionic permeability after a month of wear. The potential effect this reduction on lens movement and discomfort associated to lens wear should be further evaluated. (paper)

Efficacy of ophthalmic solutions to detach adhering Pseudomonas aeruginosa from contact lenses

NARCIS (Netherlands)

Landa, AS; van der Mei, HC; van Rij, G; Busscher, HJ

Purpose. To compare the efficacies of two all-in-one contact lens (CL) cleaning solutions and a detergent mixture on the detachment of a pathogenic bacterium adhering to two types of contact lenses in the absence and presence of a tear film. Methods. Bacterial-detachment studies were carried out in

Atomic force microscopy and scanning electron microscopy analysis of daily disposable limbal ring contact lenses.

Science.gov (United States)

Lorenz, Kathrine Osborn; Kakkassery, Joseph; Boree, Danielle; Pinto, David

2014-09-01

Limbal ring (also known as 'circle') contact lenses are becoming increasingly popular, especially in Asian markets because of their eye-enhancing effects. The pigment particles that give the eye-enhancing effects of these lenses can be found on the front or back surface of the contact lens or 'enclosed' within the lens matrix. The purpose of this research was to evaluate the pigment location and surface roughness of seven types of 'circle' contact lenses. Scanning electron microscopic (SEM) analysis was performed using a variable pressure Hitachi S3400N instrument to discern the placement of lens pigments. Atomic force microscopy (Dimension Icon AFM from Bruker Nano) was used to determine the surface roughness of the pigmented regions of the contact lenses. Atomic force microscopic analysis was performed in fluid phase under contact mode using a Sharp Nitride Lever probe (SNL-10) with a spring constant of 0.06 N/m. Root mean square (RMS) roughness values were analysed using a generalised linear mixed model with a log-normal distribution. Least square means and their corresponding 95% confidence intervals were estimated for each brand, location and pigment combination. SEM cross-sectional images at 500× and 2,000× magnification showed pigment on the surface of six of the seven lens types tested. The mean depth of pigment for 1-DAY ACUVUE DEFINE (1DAD) lenses was 8.1 μm below the surface of the lens, while the remaining lens types tested had pigment particles on the front or back surface. Results of the atomic force microscopic analysis indicated that 1DAD lenses had significantly lower root mean square roughness values in the pigmented area of the lens than the other lens types tested. SEM and AFM analysis revealed pigment on the surface of the lens for all types tested with the exception of 1DAD. Further research is required to determine if the difference in pigment location influences on-eye performance. © 2014 The Authors. Clinical and Experimental

Performance of Lotrafilcon B silicone hydrogel contact lenses in experienced low-Dk/t daily lens wearers.

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Dillehay, Sally M; Miller, Marian B

2007-11-01

The silicone hydrogel lens O2OPTIX with a Dk/t of 138 (at -3.00 diopters [D]) was evaluated and compared with patients' habitual low-Dk/t lenses. This large, multisite (United States and Canada), single-masked study enrolled experienced daily-wear, low-Dk/t, 2-week replacement soft contact lens wearers. Subjects underwent baseline evaluations and were fitted with O2OPTIX lenses for a 2-week period. After 2 weeks, subjects returned for assessment versus their habitual lenses. Data for 760 subjects were analyzed. The overall average habitual contact lens power was -3.13 D, and the average O2OPTIX lens power was -3.22 D. Biomicroscopy evaluations showed improvements in signs related to corneal health with O2OPTIX. Conjunctival and limbal redness, corneal neovascularization, corneal edema, and corneal and conjunctival staining all decreased significantly from baseline. O2OPTIX lenses performed better than habitual lenses in terms of comfort, symptoms, and overall preference. When wearing O2OPTIX lenses, significantly fewer subjects reported problems compared to their habitual lenses, including uncomfortable lens wear (-20.3%), redness (-44.5%), dryness during the day (-40.2%), and dryness at the end of the day (-34.4%); 47.9% reported that they could wear O2OPTIX lenses longer than their habitual lenses. At the end of study, among those with a preference, a significantly greater proportion of patients (60.3%) preferred O2OPTIX lenses to their habitual lenses. Daily wear of O2OPTIX lenses resulted in improvements in corneal signs of health and patient symptoms and provided excellent vision and comfort. O2OPTIX lenses were preferred by subjects over their habitual lenses.

Oxygen permeability of the pigmented material used in cosmetic daily disposable contact lenses.

Science.gov (United States)

Galas, Stephen; Copper, Lenora L

2016-01-01

To evaluate the individual contributions of pigment colorant and packing solution containing polyvinyl pyrrolidone (PVP) on the oxygen permeability (Dk) of a cosmetic printed etafilcon A daily disposable contact lens packaged with PVP. The oxygen transport of a contact lens is evaluated through the central optical zone of the lens. Cosmetic printed contact lenses contain pigment colorant in the periphery or mid-periphery of the lens. Therefore, to assess the impact of cosmetic print on oxygen permeability, special lenses need to be produced that contain the colorant within the central optical zone. This technique was used to obtain multiple measurements of nonedge-corrected Dk/t of both the center pigmented lens and its nonpigmented equivalent, using a polarographic measurement described in International Organization for Standardization (ISO) 18369-4:2006(E), and the Dk derived for each measurement is corrected for edge effect. In addition, the edge-corrected Dk values of lenses made from the same monomer batch were measured. The lenses were packaged and autoclaved with and without proprietary technology which embeds PVP in the contact lens during autoclaving. The resulting Dk value of the printed lens material was then used with thickness data to generate true Dk/t profiles for a given lens power. The edge-corrected Dk of the printed etafilcon A lens with offset pigment colorant was measured to be 19.7×10 -11 (cm 2 /s) (mL O 2 /mL·mmHg) at 35°C. This was within ±20% tolerance range as specified in ISO 18369-2:2012(E) for the edge-corrected Dk of the nonpigmented etafilcon A control lens evaluated during the same session, 19.5×10 -11 (cm 2 /s) (mL O 2 /mL·mmHg). The edge-corrected Dk values of the lenses packaged with PVP (mean 20.1, standard deviation [SD] 0.3) were also within the ±20% tolerance range compared to those packaged without PVP (mean 20.0, SD 0.3). The pigment colorant and PVP embedded in the contact lens during autoclaving were not found to

The effects of the modulus of the lens material on intraocular pressure measurement through soft contact lenses.

Science.gov (United States)

Boyraz, S; Güngör, I

2013-09-01

To investigate the effects of the modulus of the lens material on the intraocular pressure measurement using the Tono-Pen XL applanation tonometer through soft contact lenses. Thirty eyes of 15 patients with myopia were evaluated. Intraocular pressure (IOP) measurements were performed using Tono-Pen XL directly over cornea, and subsequently through three soft contact lenses made up of different lens materials. All were -3.00 diopter soft contact lenses: lotrafilcon A with a low water content (24%) and high modulus (1.4 MPa) (CL-I), balafilcon A with a moderate water content (36%) and moderate modulus (1.1 MPa) (CL-II), and vifilcon A with a moderate water content (55%) and low modulus (0.79 MPa) (CL-III). IOP measurements through contact lenses were compared with each other, and with direct corneal measurements. The mean age of the patients (11 males and 4 females) was 26.86±5.62 years. All measurements obtained through CLs were significantly higher than the direct corneal measurements. The measurements through CLs differed by 4.61±0.54 mmHg (P=0,001), 2.9±0.46 mmHg (P=0.001), and 1.94±0.51 mmHg (P=0,003) for CL-I, CL-II and CL-III, respectively. In the paired comparisons of measurements through CLs, all comparisons were significant except the comparison of measurements through CL-II and CL-III (P=0.128). IOP measurements through silicone-hydrogel contact lenses with a high modulus and low water content were higher compared to the other contact lenses. While measuring IOP through CLs, the clinicians should consider the effect of the lens material and the features of the device used.

The measurement of intraocular pressure over positive soft contact lenses by rebound tonometry.

Science.gov (United States)

Zeri, Fabrizio; De Cusatis, Mario; Lupelli, Luigi; Swann, Peter Graham

2016-01-01

To investigate if the accuracy of intraocular pressure (IOP) measurements using rebound tonometry over disposable hydrogel (etafilcon A) contact lenses (CL) is affected by the positive power of the CLs. The experimental group comprised 26 subjects, (8 male, 18 female). IOP measurements were undertaken on the subjects' right eyes in random order using a Rebound Tonometer (ICare). The CLs had powers of +2.00D and +6.00D. Measurements were taken over each contact lens and also before and after the CLs had been worn. The IOP measure obtained with both CLs was significantly lower compared to the value without CLs (t test; p<0.001) but no significant difference was found between the two powers of CLs. Rebound tonometry over positive hydrogel CLs leads to a certain degree of IOP underestimation. This result did not change for the two positive lenses used in the experiment, despite their large difference in power and therefore in lens thickness. Optometrists should bear this in mind when measuring IOP with the rebound tonometer over plus power contact lenses. Copyright © 2016 The Authors. Published by Elsevier Espana.. All rights reserved.

Aberration changes of the corneal anterior surface following discontinued use of rigid gas permeable contact lenses.

Science.gov (United States)

Yu, Qing; Wu, Jiang-Xiu; Zhang, He-Ning; Ye, Sheng; Dong, Shi-Qi; Zhang, Chen-Hao

2013-01-01

To record aberrations with a corneal topographic device on the anterior surface of the cornea at different time-points prior to wearing and following discontinued use of rigid gas permeable (RGP) contact lenses. The effect of wearing RGP on the anterior surface of the cornea was discussed to provide guidance for clinical refractive error correction. The study objects were 24 eyes from 24 patients. All patients underwent identical examination procedures prior to lens use, as well as afterwards, including slit-lamp examination, non-contact tonometer measurement, computer optometry and corneal curvature measurement, subjective refraction test, and corneal topography analysis. The patients wore contact lenses everyday for 1 month and then discontinued. Corneal topographies were recorded at certain time points of 30 minutes, 1 day, 3, 7 and 14 days following use. Total corneal aberration at each time point following discontinued use of RGP contact lenses was less than the time point prior to use. Detailed results were as follows: root mean square (RMS) (pre)=(1.438±0.328)µm, RMS (30 minutes)=(1.076±0.355)µm, RMS (1 day)=(1.362±0.402)µm, RMS (3 days)=(1.373±0.398)µm, RMS (7 days)=(1.387±0.415)µm, and RMS (14 days)=(1.430±0.423)µm. Results showed that at 30 minutes after discontinued use of RGP contact lenses, almost all 2(nd)- and 3(rd)-order aberrations change. Quadrafoil Z10 and spherical Z12 of the 4(th)-order were also changed. Alterations to Z5, Z6, and Z12 at 1 day after discontinued use were significant differences compared with the time period prior to RGP use: Z5 and Z6 decreased, and Z12 increased slightly. Z5 and Z6 remained decreased at 3 days after discontinued use, but Z9 and Z10 continued to increase and Z12 returned to levels prior to RGP use. At 14 days after discontinued use, all aberrations were not significantly different from the values prior to use. The use RGP contact lenses greatly reduced total aberration of the anterior surface of

Prevention of the adverse photic effects of peripheral light-focusing using UV-blocking contact lenses.

Science.gov (United States)

Kwok, L Stephen; Kuznetsov, Valerian A; Ho, Arthur; Coroneo, Minas T

2003-04-01

Peripheral light-focusing (PLF) is an occult form of ultraviolet radiation (UVR) hazardous to the human eye. In PLF, obliquely incident light is refracted from the peripheral cornea to concentrated sites inside the anterior segment. In the current study, the directionality of this phenomenon for UVR and whether PLF is established in outdoor settings exposed to sunlight were investigated. The protection provided by a UV-blocking contact lens was also evaluated. UVA and UVB sensors were placed on the nasal limbus of an anatomically based model eye. The temporal limbus was exposed to a UV light source placed at various angles behind the frontal plane. PLF was quantified with the sensor output. The ensemble was mounted in the orbit of a mannequin head and exposed to sunlight in three insolation environments within the region of Sydney, Australia. PLF for UVA and UVB was determined with no eyewear or with sunglasses and commercially available soft contact lenses, with and without UV-blocking capability. The intensity of UVA peaked at approximately 120 degrees incidence, the level at which the UVB response was also at its maximum. The intensification of UVA was up to x18.3. The intensity of PLF for UVA and UVB was reduced by an order of magnitude by a UV-blocking contact lens, whereas a clear contact lenses had a much lesser effect. Only the UV-blocking contact lens achieved a significant effect on UVA and UVB irradiance in the urban, beach, and mountain locales (P UV-blocking soft contact lenses. Sunglasses may be unable to shield oblique rays, unless side protection is incorporated. Contact lenses can offer UVR protection against all angles of incidence, including the peak-response angle. They can also protect the eye in settings in which the wearing of sunglasses is not feasible or convenient.

Ocular physiology and comfort in neophyte subjects fitted with daily disposable silicone hydrogel contact lenses.

Science.gov (United States)

Morgan, Philip B; Chamberlain, Paul; Moody, Kurt; Maldonado-Codina, Carole

2013-06-01

To evaluate the performance of a silicone hydrogel daily disposable lens in neophyte subjects over 12 months. Seventy four subjects with no previous contact lens experience were randomised to wear narafilcon A (1 DAY ACUVUE(®) TruEye™) lenses (LW group) or to wear no contact lenses (NLW group) for 12 months. Biomicroscopy (performed by a masked investigator), visual acuity and subjective response scores were recorded at an initial visit and six follow-up visits, in addition to lens fit and surface evaluation for the LW group. Comfort was recorded with SMS messaging. Fifteen of the LW group discontinued before the end of the study, compared with six of the NLW group. Measured visual acuity was about half a line better for the NLW group as these subjects were provided with their full sphero-cylindrical over-refraction, compared to the LW group in their best spherical corrected contact lenses; subjective scores for vision were similar for the two groups. Bulbar conjunctival hyperaemia, limbal hyperaemia, corneal staining, conjunctival staining and papillary conjunctivitis were clinically equivalent for the two groups whereas conjunctival staining was higher in the LW group. Comfort scores assessed by SMS were equivalent for the LW and NLW groups; there was a measurable improvement in comfort during the first month of wear for the LW group. This work has demonstrated that modern soft lenses (narafilcon A daily disposable silicone hydrogel lenses) offer an excellent, comfortable form of vision correction, and are able to exhibit minimal alterations to ocular physiology. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Influence of day and night wear on surface properties of silicone hydrogel contact lenses and bacterial adhesion.

Science.gov (United States)

Vermeltfoort, Pit B J; Rustema-Abbing, Minie; de Vries, Joop; Bruinsma, Gerda M; Busscher, Henk J; van der Linden, Matthijs L; Hooymans, Johanna M M; van der Mei, Henny C

2006-06-01

The aim of this study was to determine the effect of continuous wear on physicochemical surface properties of silicone hydrogel (S-H) lenses and their susceptibility to bacterial adhesion. In this study, volunteers wore 2 pairs of either "lotrafilcon A" or "balafilcon A" S-H contact lenses. The first pair was worn continuously for a week and the second pair for 4 weeks. One lens of each pair was used for surface characterization and the other one for bacterial adhesion experiments. Lens surfaces were characterized by examination of their wettability, roughness, elemental composition, and proteins attached to their surfaces. Adhesion of Staphylococcus aureus 835 and Pseudomonas aeruginosa #3 to a lens was studied using a parallel plate flow chamber. Before use, the lotrafilcon A lens was rougher than the balafilcon A lens and had a lower water contact angle and a higher affinity for S. aureus 835. After wear, both lens types had similar water contact angles, whereas the differences in elemental surface composition decreased as well. S. aureus 835 adhered in higher numbers to worn balafilcon A lenses, whereas the opposite was seen for P. aeruginosa #3. The initial deposition rates of both bacterial strains to lotrafilcon A lenses decreased by wearing and were found to correlate significant (P lenses. In this study, the differences in surface properties between 2 types of S-H lenses were found to change after 1 week of continuous wear. Generally, bacteria adhered in lower numbers and less tenaciously to worn lenses, except S. aureus 835, adhering in higher numbers to worn balafilcon A lenses.

Deposition of lipid, protein, and secretory phospholipase A2 on hydrophilic contact lenses.

Science.gov (United States)

Mochizuki, Hiroshi; Yamada, Masakazu; Hatou, Shin; Kawashima, Motoko; Hata, Seiichiro

2008-01-01

Recent studies have shown that low tear phospholipid levels are associated with tear film instability in hydrophilic contact lens wearers. The concentration of secretory phospholipase A2 (sPLA2), the enzyme that hydrolyzes phospholipids, in tears is known to exceed the levels found in serum by four orders of magnitude. This study was performed to determine the levels of sPLA2 from the deposition on two different frequent-replacement contact lens materials. Polymacon and etafilcon A contact lenses worn for 2 weeks by 16 experienced contact lens wearers were used for the analysis. Total lipids were determined by the sulfo-phospho-vanillin reaction. Phospholipids in lipid extracts were estimated by phosphorus determination with ammonium molybdate through enzymatic digestion. Total protein was measured by bicinchoninic acid analysis. Double-antibody sandwich enzyme-linked immunosorbent assay was used to determine sPLA2 concentrations. Total lipid deposition was found to be greater in the polymacon group (66.3+/-16.3 microg/lens) than in the etafilcon A group, although phospholipids were not detected in either group. The etafilcon A group had greater deposition of protein (3.7+/-0.7 mg/lens) than the polymacon group had. The etafilcon A group deposited statistically significantly more group IIa sPLA2 (1.1+/-0.3 microg/lens) than the polymacon group (0.07+/-0.04 microg/lens) did (P<0.001). There was a significant difference in the lipid and protein deposition profiles in the two lenses tested. A significant amount of sPLA2 in the deposition on contact lenses may play a role in tear film instability in hydrophilic contact lens wearers.

Vision of low astigmats through thick and thin lathe-cut soft contact lenses.

Science.gov (United States)

Cho, P; Woo, G C

2001-01-01

Distance and near visual acuity of 13 low astigmats were determined in a double-masked experiment through thick and thin (centre thickness 0.12 mm and 0.06 mm, respectively) spherical lathe-cut soft lenses. For each lens type, distance and near LogMAR VA and over-refraction were assessed with different logMAR VA charts. For 70% of the subjects, the residual astigmatism was significantly lower than the refractive astigmatism with thicker lenses. No statistically significant differences in the distance and near logMAR VA was found between the two lens types using any of the charts used, though, in general, logMAR VA obtained through the thicker lens was better than logMAR VA through the thinner lens. The variabilities in distance and near logMAR VA between the two lens types increased with decreased contrast. The variabilities in distance logMAR VA were greater with Chinese charts than with English charts, and LogMAR VA with Chinese charts were significantly worse for both lens types. Based on the results of this study, we concluded that thicker spherical lathe-cut soft lenses provide better vision in low astigmats. The Snellen acuity test is inadequate for vision assessment of soft contact lens wearers. When a patient wearing thin soft contact lenses complains of poor vision in spite of 6/6 or 6/5 Snellen acuity, changing to thicker lenses may be considered.

Bilateral Acanthamoeba ulcer in a user of disposable soft contact lenses: a tragic incident or a consequence of the aggressive policy of soft contact lens trading?

Science.gov (United States)

Sousa, Sidney Júlio de Faria E; Dias, Vanderson Glerian; Marcomini, Luís Antonio Gorla

2008-01-01

This is the report of a case of bilateral Acanthamoeba keratitis in a 19-year-old woman who bought a pair of disposable soft contact lenses in a boutique. She wore this same pair of lenses for 3 months daily without the appropriate care. This led to bilateral corneal transplantation with cataract extraction and also trabeculectomy in the right eye. When last seen, both grafts were crystal clear but the visual acuities were far from satisfactory. She also had bilateral secondary glaucoma, barely controlled by topical medication. Actually, the physical features and the wearing time characteristics of the disposable soft contact lenses created unprecedented difficulties to the medical surveillance of their wearers. Without the right assistance they tend to become careless regarding routine cleaning. They also feel free to buy less expensive lenses, to use saline instead of lens solutions, to violate the limits of wearing time and to extend the use over the sleeping period. Additionally, the aggressive marketing and the wide distribution of these lenses increase the chances that economically or educationally unprepared people will acquire them. The question that remains is: Is the present case an accidental event or an example of what is likely to happen in the future if the indiscriminate selling of disposable soft contact lenses continues to evolve?

Bacterial populations on silicone hydrogel and hydrogel contact lenses after swimming in a chlorinated pool.

Science.gov (United States)

Choo, Jennifer; Vuu, Kathy; Bergenske, Peter; Burnham, Kara; Smythe, Jennifer; Caroline, Patrick

2005-02-01

A number of reports have indicated an association between swimming with contact lenses and subsequent eye infection. This study tests whether a hydrophilic contact lens worn while swimming accumulates bacteria present in the water. It was of interest to determine whether lens type (silicone hydrogel vs. hydrogel) affected the result. Fifteen healthy noncontact lens wearers swam for 30 minutes with a silicone hydrogel lens (PureVision, Bausch & Lomb, Rochester, NY) on one eye and a hydrogel lens (Acuvue 2, Vistakon Inc., Jacksonville, FL) on the other. Lenses were removed aseptically and placed in sterile vials 10 minutes after the subjects left the water. Microbial growth was enumerated for total numbers of colonies and categorized by species present. Numbers of colonies were compared between the two lens groups and with a water sample taken from the pool at the time of the experiment. Eight of the subjects returned on a different day and wore new lenses for 50 minutes in normal room conditions. Two lenses were lost while swimming. Twenty-seven of the remaining 28 lenses worn while swimming showed colonization, principally with Staphylococcus epidermidis, which was also by far the most common species identified from the water itself. Small numbers of Staphylococcus aureus and Streptococcus salivarius were also present in the water and on the lenses. Numbers of colonies varied among subjects (range, 0 to 230), but no differences were observed between the two lens groups. Lenses removed after 30 minutes of wear without swimming were mostly sterile, with 3 of 16 lenses showing just two colonies each. It appears that wearing a hydrophilic lens while swimming allows accumulation of microbial organisms on or in the lens, regardless of lens material. Swimmers should be advised to wear tight-fitting goggles if lenses are worn while swimming, and thorough disinfection of the lenses before overnight wear seems prudent.

Aberration changes of the corneal anterior surface following discontinued use of rigid gas permeable contact lenses

Directory of Open Access Journals (Sweden)

Shi-Qi Dong

2013-04-01

Full Text Available AIM: To record aberrations with a corneal topographic device on the anterior surface of the cornea at different time-points prior to wearing and following discontinued use of rigid gas permeable (RGP contact lenses. The effect of wearing RGP on the anterior surface of the cornea was discussed to provide guidance for clinical refractive error correction. METHODS: The study objects were 24 eyes from 24 patients. All patients underwent identical examination procedures prior to lens use, as well as afterwards, including slit-lamp examination, non-contact tonometer measurement, computer optometry and corneal curvature measurement, subjective refraction test, and corneal topography analysis. The patients wore contact lenses everyday for 1 month and then discontinued. Corneal topographies were recorded at certain time points of 30 minutes, 1 day, 3, 7 and 14 days following use. RESULTS: Total corneal aberration at each time point following discontinued use of RGP contact lenses was less than the time point prior to use. Detailed results were as follows:root mean square (RMS (pre=(1.438±0.328μm, RMS (30 minutes=(1.076±0.355μm, RMS (1 day=(1.362±0.402μm, RMS (3 days=(1.373±0.398μm, RMS (7 days=(1.387±0.415μm, and RMS (14 days=(1.430±0.423μm. Results showed that at 30 minutes after discontinued use of RGP contact lenses, almost all 2nd- and 3rd-order aberrations change. Quadrafoil Z10 and spherical Z12 of the 4th-order were also changed. Alterations to Z5, Z6, and Z12 at 1 day after discontinued use were significant differences compared with the time period prior to RGP use:Z5 and Z6 decreased, and Z12 increased slightly. Z5 and Z6 remained decreased at 3 days after discontinued use, but Z9 and Z10 continued to increase and Z12 returned to levels prior to RGP use. At 14 days after discontinued use, all aberrations were not significantly different from the values prior to use. CONCLUSION: The use RGP contact lenses greatly reduced total

Comparison of tear osmolarity and ocular comfort between daily disposable contact lenses: hilafilcon B hydrogel versus narafilcon A silicone hydrogel.

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Sarac, Ozge; Gurdal, Canan; Bostancı-Ceran, Basak; Can, Izzet

2012-06-01

The aim of this study was to evaluate tear osmolarity and ocular comfort with two different types of hydrogel daily disposable lenses. The right eyes of 15 first-time contact lens users were included in this prospective study. All eyes wore hilafilcon B silicone hydrogel contact lenses for 8 h (group 1). After 1 week without contact lenses, all eyes wore narafilcon A silicone hydrogel contact lenses for 8 h (group 2). Tear osmolarity measurement was performed before and after 4 and 8 h of each contact lens wear. Ocular comfort was assessed after 4 and 8 h of each contact lens wear. In group 1, the mean baseline, 4- and 8-h tear osmolarity values were 293 ± 10.57, 303.00 ± 10.5 mOsm/L (p = 0.023), and 295.0 ± 1.4 mOsm/L (p > 0.05), respectively. In group 2, the mean baseline, 4- and 8-h tear osmolarity values were 294 ± 13.65, 300.9 ± 11.3 mOsm/L (p = 0.007), and 298.80 ± 7.2 mOsm/L (p > 0.05), respectively. In group 1, the mean comfort score was 7.20 ± 0.45 and 8.60 ± 0.45 at 4 and 8 h, respectively (p = 0.038). In group 2, the mean comfort score significantly decreased from 9.80 ± 0.45 to 7.80 ± 0.84 at 4 h (p = 0.039). Both hydrogel and silicone hydrogel daily disposable contact lenses elevated tear osmolarity during 8 h of contact lens wear. The increase in tear osmolarity with both contact lenses was below the cut-off value for dry eye and was not associated with ocular comfort.

The effect of surface treatment of silicone hydrogel contact lenses on the attachment of Acanthamoeba castellanii trophozoites.

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Beattie, Tara K; Tomlinson, Alan

2009-11-01

To determine if plasma surface treatment of Focus Night & Day silicone hydrogel contact lenses affects the attachment of Acanthamoeba. Unworn lotrafilcon A contact lenses with (Focus Night & Day) and without surface treatment and Acuvue, conventional hydrogel lenses, were quartered before 90-min incubation with Acanthamoeba castellanii trophozoites. After incubation and rinsing, the trophozoites attached to one surface of each quarter were counted by direct light microscopy. Sixteen replicates were observed for each lens type. Logarithmic transformation of data allowed the use of parametric analysis of variance. No significant difference in attachment was established between the untreated lotrafilcon A and the conventional hydrogel lenses (Ptreatment of the native Focus Night & Day material produced a significant increase in attachment (Ptreatment to reduce lens hydrophobicity; however, this procedure results in an enhanced acanthamoebal attachment. It is possible that the silicone hydrogel lens could be at a greater risk of promoting Acanthamoeba infection if exposed to the organism because of the enhanced attachment characteristic of this material. Eye care professionals should be aware of the enhanced affinity that Acanthamoeba show for this lens and accordingly emphasise to patients the significance of appropriate lens hygiene. This is particularly important where lenses are worn in a regime that could increase the chance of exposure to the organism, i.e., 6 nights/7 days extended wear or daily wear, where lenses will be stored in a lens case, or where lenses are worn when in contact with potentially contaminated water sources, i.e., swimming or showering.

Studies on Development of Polymeric Materials Using Gamma Irradiation for Contact and Intraocular Lenses

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Pranshu Chhabra

2009-01-01

Full Text Available For the development of materials for contact lenses and intraocular lenses, the selection criteria is based on the (i capacity to absorb and retain water, (ii hydrophilicity and hydrophobicity, (iii refractive index and (iv hardness besides the other essential properties. Various monomers are being studied to develop suitable materials for such applications. Selection of suitable monomers that can be converted into optical materials of desired characteristics is the most essential step. In the present paper, an attempt has been made to develop suitable optical polymers based on 2-hydroxy ethyl methacrylate (HEMA, N-vinyl pyrrolidone (NVP, methyl methacrylate (MMA, methacrylic acid (MAA, and styrene. Compositions were prepared in such a way that polymers of varying hydrophilicity or hydrophobicity could be obtained keeping HEMA as the base (main monomer. For polymerization, gamma irradiation (Co-60 as a source was used. The results of the study showed that: (i an increase in NVP and MAA content brought in an increase in hydrophilicity of polymerized HEMA (pHEMA, while the addition of styrene and MMA decreased hydrophilicity of polymerized HEMA (pHEMA, (ii polymers for contact lenses with water retention capacity as high as >50 wt.% and as low as <10 wt% with varying content of suitable comonomers can be designed, (iii polymeric materials for contact lenses can be made by using radiation processing such as Co-60 and (iv a dose of 40 kGy was found to be ideal for purpose.

Clinical comparison of the (polymacon) spin-cast hydrogel contact lens to the (polymacon) lathe-cut hydrogel lenses.

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Hill, J F

1980-08-01

The purpose of this study was to compare the clinical acceptability of polymacon spin-cast to polymacon lathe-cut hydrophilic contact lenses. Ten patients successfully wearing polymacon spin-cast lenses were studied. Each patient had one eye refitted with polymacon lathe-cut lenses. Comparison of the two types of lenses was then made. Objective evaluation included centration, movement, visual acuity, and over-refraction. Subjective criteria were based on patient comfort and stability and quality of vision. Results indicate that lathe-cut lenses can be just as clinically satisfactory as the spincast ones.

Cosmetic Cleansing Oil Absorption by Soft Contact Lenses in Dry and Wet Conditions.

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Tsukiyama, Junko; Miyamoto, Yuko; Kodama, Aya; Fukuda, Masahiko; Shimomura, Yoshikazu

2017-09-01

Previous reports showed that cosmetic cleansing oil for removing makeup, which contains mineral oil and surfactant, can deform some silicone hydrogel contact lenses (SHCLs) when applied directly to the lenses, although plasma-coated SHCLs (lotrafilcon A and B) were not affected. In the present study, we investigated hydrogel lenses and SHCLs in both wet and dry conditions. Several brands of hydrogel and SHCLs were immersed in a cleansing oil solution containing Sudan Black B for 5 min under wet and dry conditions. The lenses under the wet condition were simply picked up from the saline, whereas those under the dry condition were blotted with paper wipes. After immersing, the excess solution remaining on the lenses was removed by finger rubbing with a multipurpose solution. The lenses were then examined using a stereomicroscope, and their mean brightness was measured and compared. The cosmetic cleansing oil was not absorbed by the hydrogel lenses under wet or dry conditions. However, four of seven brands of SHCLs absorbed the cosmetic cleansing oil under both conditions (dry and wet), whereas asmofilcon A absorbed it only under the dry condition. Lotrafilcon B and delefilcon A did not absorb cleansing oil even under the dry condition. Hydrogel lenses resist cosmetic cleansing oil. However, SHCLs have different degrees of resistance depending on the lens material. Some SHCLs absorbed cosmetic cleansing oil more under dry conditions than under wet conditions.

Bacterial transmission from contact lenses to porcine corneas : An ex vivo study

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Vermeltfoort, Pit B. J.; van Kooten, Theo G.; Bruinsma, Gerda .; Hooymans, Anneke M. M.; van der Mei, Henny C.; Busscher, Henk J.

PURPOSE. To quantify the transmission to ex vivo porcine eyes of Staphylococcus aureus 835 and Pseudomonas aeruginosa 3 from three types of contact lenses - one daily wear and two extended wear - differing in hydrophobicity and roughness. METHODS. One daily wear lens (etafilcon) and two

Bacterial Colonization of Disposable Soft Contact Lenses Is Greater during Corneal Infiltrative Events than during Asymptomatic Extended Lens Wear

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Sankaridurg, Padmaja R.; Sharma, Savitri; Willcox, Mark; Naduvilath, Thomas J.; Sweeney, Deborah F.; Holden, Brien A.; Rao, Gullapalli N.

2000-01-01

Microorganisms, especially gram-negative bacteria, are considered to play a role in the etiology of certain corneal infiltrative events (CIEs) observed during soft contact lens wear. This study explored the possibility of microbial colonization of soft contact lenses as a risk factor leading to CIEs. In a clinical trial conducted from March 1993 to January 1996, 330 subjects wore disposable soft contact lenses on a 6-night extended-wear and disposal schedule. During this period, 4,321 lenses (118 during CIEs; 4,203 during asymptomatic lens wear) were recovered aseptically and analyzed for microbial colonization. A greater percentage of lenses were free from microbial colonization during asymptomatic wear than during CIEs (42 versus 23%; P bacteria, gram-negative bacteria and fungi was greater during CIEs than during asymptomatic lens wear (P bacteria were isolated most frequently and were usually normal external ocular microbiota. Of the gram-positive bacteria, the incidence of Streptococcus pneumoniae was greater during CIE than during asymptomatic wear (7.6 versus 0.6%; P bacteria were seen in few cases during asymptomatic wear, their incidence during CIE in comparison to asymptomatic wear was substantial and significant (23.7 versus 3.8%; P bacteria or S. pneumoniae. Colonization of soft contact lenses with pathogenic bacteria, especially gram-negative bacteria and S. pneumoniae, appears to be a significant risk factor leading to CIE. PMID:11101574

Power profiles and short-term visual performance of soft contact lenses.

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Papas, Eric; Dahms, Anne; Carnt, Nicole; Tahhan, Nina; Ehrmann, Klaus

2009-04-01

To investigate the manner in which contemporary soft contact lenses differ in the distribution of optical power within their optic zones and establish if these variations affect the vision of wearers or the prescribing procedure for back vertex power (BVP). By using a Visionix VC 2001 contact lens power analyzer, power profiles were measured across the optic zones of the following contemporary contact lenses ACUVUE 2, ACUVUE ADVANCE, O2OPTIX, NIGHT & DAY and PureVision. Single BVP measures were obtained using a Nikon projection lensometer. Visual performance was assessed in 28 masked subjects who wore each lens type in random order. Measurements taken were high and low contrast visual acuity in normal illumination (250 Cd/m), high contrast acuity in reduced illumination (5 Cd/m), subjective visual quality using a numerical rating scale, and visual satisfaction rating using a Likert scale. Marked differences in the distribution of optical power across the optic zone were evident among the lens types. No significant differences were found for any of the visual performance variables (p > 0.05, analysis of variance with repeated measures and Friedman test). Variations in power profile between contemporary soft lens types exist but do not, in general, result in measurable visual performance differences in the short term, nor do they substantially influence the BVP required for optimal correction.

Intraocular pressure measurements in relation to head position and through soft contact lenses: comparison of three portable instruments.

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Klein, Ainat; Shemesh, Gabi; Loewenstein, Anat; Kurtz, Shimon

2011-01-01

to compare the reproducibility of three portable instruments-the Tono-Pen tonometer (Reichert Ophthalmic Instruments, Depew, NY), the Phosphene tonometer (Bausch & Lomb, Rochester, NY), and the TERT (Through Eyelid Russian Tonometer; Rjazan State Instrument Making, Rjazan, Russia)-in the measurement of intraocular pressure (IOP) with and without soft contact lenses and in different head positions. twenty-six eyes of healthy volunteers were examined by the three instruments while the subjects were sitting, recumbent, and hyperextending their heads, and with and without contact lenses. IOP measurements were compared and the effects of head position and presence of contact lenses on the resultant values were analyzed. the average difference between the recumbent and sitting positions was 3.56, 2.68, and 2.62 mm Hg for the Tono-Pen tonometer, Phosphene tonometer, and TERT, respectively. There was an increase of 5.60, 2.78, and 2.63 mm Hg in hyperextension compared to sitting for the Tono-Pen tonometer, Phosphene tonometer, and TERT, respectively. The difference in the IOP values obtained in the presence and absence of therapeutic contact lens for the three instruments in the three positions was between -1.23 and +1.47 mm Hg. IOP measurements of bedridden patients are only slightly higher than those of sitting patients except for the Tono-Pen tonometer in the hyperextension position. The presence of contact lenses does not affect IOP values obtained by the three evaluated instruments.

[Analysis of aberration changes of the corneal anterior surface following discontinued use of rigid gas permeable contact lenses].

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Yu, Qing; Wu, Jiang-xiu; Zhang, He-ning; Ye, Sheng; Dong, Shi-qi; Zhang, Chen-hao

2011-04-01

The present study used a corneal topographic device to record aberrations on the anterior surface of the cornea at different time-points prior to wearing and following discontinued use of rigid gas permeable (RGP) contact lenses. The effect of wearing RGPCL on the anterior surface of the cornea was discussed to provide guidance for clinical refractive error correction. The study objects were 60 eyes from 30 patients. All patients underwent identical examination procedures prior to lens use, as well as afterwards, including slit-lamp examination, non-contact tonometer measurement, computer optometry & corneal curvature measurement, subjective refraction test, and corneal topography analysis. The patients wore contact lenses every day for 1 month and then discontinued. Corneal topographies were recorded at certain time points of 30 min, 1 day, 3 days, 1 week, and 2 weeks following use. Total corneal aberration at each time point following discontinued use of RGP contact lenses was less than the time point prior to use. Detailed results are as follows; root mean square (RMS) (pre) = (1.438 ± 0.328), RMS (30 min) = (1.076 ± 0.355), RMS (1 day) = (1.362 ± 0.402), RMS (3 day) = (1.373 ± 0.398), RMS (7 day) = (1.387 ± 0.415), and RMS (14 day) = (1.448 ± 0.423). Results showed that at 30 minutes after discontinued use of RGP contact lenses, almost all 2(nd)- and 3(rd)-order aberrations were altered. Quadrafoil Z10 and spherical Z12 of the 4(th)-order were also changed. Alterations to Z5, Z6, and Z12 at 1 day after discontinued use were significant compared with the time period prior to RGP use: Z5 and Z6 decreased, and Z12 increased slightly (F = 2.869 ∼ 5.549, P = 0.001 ∼ 0.042). Z5 and Z6 remained decreased at 3 days after discontinued use, but Z9 and Z10 continued to increase and Z12 returned to levels prior to RGP use (P > 0.05). At 2 weeks after discontinued use, all aberrations were not significantly different from the values prior to use (P > 0.05). The

The impact of cellular debris on Pseudomonas aeruginosa adherence to silicone hydrogel contact lenses and contact lens storage cases.

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Burnham, Geoffrey W; Cavanagh, H Dwight; Robertson, Danielle M

2012-01-01

To evaluate neutrophil-enhanced Pseudomonas aeruginosa (PA) biofilm formation on silicone hydrogel contact lenses and to determine the effect of epithelial biodebris on PA adherence in contact lens storage cases. A fully invasive PA corneal isolate stably conjugated to green fluorescent protein was used. Unworn lotrafilcon A contact lenses were incubated at various ratios of PA to polymorphonuclear neutrophil (PMN) for 24 hours at 37°C. Lens-associated PA was evaluated using laser scanning confocal microscopy and nonviable PA were visualized using propidium iodide. Viable bacteria were enumerated by colony-forming unit (CFU) analysis. For acute epithelial cell studies, PA viability was determined after coincubation with freeze-thaw epithelial cell lysates in 96-well polystyrene plates. Levels of residual cellular debris and bacterial viability were further assessed in used contact lens storage cases. Laser scanning confocal microscopy demonstrated that cotreatment with PMA-stimulated neutrophils increased PA adherence over 24 hours to lens surfaces with a striking alteration of PA architecture. Propidium iodide staining showed that the adherent bacteria consisted of a mixture of viable and nonviable PA; a PMN-associated increase in viable PA was confirmed by CFU (PA:PMN 0.1:1, P = 0.025; PA:PMN 1:1, P = 0.005). Acute epithelial cell debris studies revealed a significant increase in viable PA in 96-well plates in the presence of epithelial freeze-thaw lysates (PA:debris 1:1, P = 0.002; PA:debris 100:1, P = 0.002). Crystal violet staining of used lens storage cases revealed residual cellular debris at all time points, which was independent of microbial contamination; all lens cases used for periods of 9 months or more were uniformly associated with high levels of viable microorganisms. These results demonstrate that prolonged corneal inflammation with the presence of PMNs when confronted with simultaneous PA challenge in extended contact lens wear has the potential

Changes in corneal structure with continuous wear of high-Dk soft contact lenses: a pilot study.

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González-Méijome, J M; González-Pérez, J; Cerviño, A; Yebra-Pimentel, E; Parafita, M A

2003-06-01

Despite numerous studies that have considered the effects of extended wear of high-Dk soft contact lenses on ocular physiology, little attention has been paid to the impact of such lenses on central or peripheral corneal thickness and curvature. The present study aims to report the time course of changes in corneal thickness and curvature that accompanies the 30-night continuous wear of new silicone hydrogel soft contact lenses in a neophyte population in a longitudinal study. Six subjects wore high-Dk lotrafilcon (Dk = 140) on a 30-night replacement schedule for 12 months. Only measurements from the right eye were considered for analysis. Topographical measurements of corneal thickness and curvature were taken. The same parameters were monitored for an additional period of 3 months after lens removal. An almost homogenous increase in corneal radius of curvature was detected for all the locations studied, being statistically significant for the 4-mm cord diameter area. This effect was associated with a progressive thinning effect for the central cornea, whereas midperipheral and peripheral areas did not display such a thinning effect during continuous wear. These effects were still evident for the central cornea 3 months after contact lens wear discontinuation. Continuous wear of high-Dk silicone hydrogel contact lenses is associated with clinically appreciable changes in topographical corneal curvature, whereas only a reduction in corneal thickness is appreciated in the central area. This effect seems to be a result of mechanical pressure induced by these hybrid hyperpermeable materials, characterized by a higher modulus of elasticity. The small sample size compromises the conclusions addressed from this study, and further work will be necessary to confirm the present results.

Microbial contamination of contact lenses after scaling and root planing using ultrasonic scalers with and without protective eyewear: A clinical and microbiological study.

Science.gov (United States)

Afzha, Rooh; Chatterjee, Anirban; Subbaiah, Shobha Krishna; Pradeep, Avani Rangaraju

2016-01-01

Ultrasonic scaler is a preferential treatment modality among the clinicians. However, the aerosol/splatter generated is a concern for patients and practitioners. Therefore, the purpose of this study was to evaluate contamination of contact lenses of the dentist after scaling and root planing using ultrasonic scalers with and without protective eyewear. Thirty patients were randomly selected for scaling and root planing and divided into 2 groups of 15 each. Group A - dentist wearing contact lenses and protective eyewear. Group B - dentist wearing only contact lenses. After scaling and root planing using ultrasonic scalers, the lenses were subjected to culture and 16S rRNA (16S ribosomal RNA) gene sequencing. In Group A - 15 out of thirty samples were contaminated, in Group B - all the thirty samples were contaminated. Most of the samples showed Gram-positive bacteria and 5 samples were contaminated with fungi. 16S rRNA gene sequencing of forty contaminated samples showed that 31 were contaminated with Streptococcus mutans and 9 with Staphylococcus aureus. Keeping in mind the limitation of the study for the absence of negative control, we would like to conclude that dental practitioners should better avoid contact lenses in a dental setup because of the risk of contamination of the contact lenses from the various dental procedures which can produce aerosol/splatter and if worn, it is recommended to wear protective eyewear.

Barriers, motivators and enablers for dispensing multifocal contact lenses in Mumbai, India.

Science.gov (United States)

Thite, Nilesh; Shah, Ukti; Mehta, Jasmin; Jurkus, Janice

2015-01-01

To understand the potential barriers, motivators and enablers in dispensing multifocal contact lenses (MFCL). Two focus group discussions were conducted to design questionnaires regarding the prescribing habits for multifocal contact lenses (MFCL). Questions on potential barriers and motivators were included. The questionnaires were distributed among 133 eye care practitioners across Mumbai, India. Practitioners fitting one or less patient per month with MFCL completed the survey describing potential barriers, while those who prescribed more MFCL's per month completed the survey describing enablers and motivators. Responses from 102 practitioners were received. Most common potential barriers in prescribing MFCL were increased chair time (75%), lack of readily available trials (69%) and limitation in power range (63%). Lack of awareness among patients (90%) was the most common barrier from patients' outlook. Professional satisfaction (88%) and better business proposition (82%) were observed as main motivators while availability of the trials (84%) and correct patient selection (82%) were the major enablers. Graduate Optometrists felt dispensing MFCL did not offer a good business proposition (p=0.02). Experienced practitioners were observed to be least motivated (p=0.01) and believed that their patients found these lenses expensive (p=0.02). To enhance the MFCL practice, barriers like lack of awareness and limitations in power range must be addressed. Trial lens availability may motivate practitioners to prescribe MFCL. Further probing is required to understand lack of motivation among experienced practitioners. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Nonadhesive, silica nanoparticles-based brush-coated contact lens casesCompromising between ease of cleaning and microbial transmission to contact lenses

NARCIS (Netherlands)

Qu, Wenwen; Hooymans, Johanna M. M.; Qiu, Jun; de-Bont, Nik; Gelling, Onko-Jan; van der Mei, Henny C.; Busscher, Henk J.

Surface properties of lens cases are determinant for their cleanability and for microbial transmission from lens cases to contact lenses (CLs). PEG-polymer-brush-coatings are known to decrease microbial adhesion more than other surface-coatings. Here, we applied a robust, silica nanoparticles-based

Peripheral refraction with dominant design multifocal contact lenses in young myopes

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Daniela Lopes-Ferreira

2013-04-01

Conclusion: It is possible to induce significant changes in the pattern of relative peripheral refraction in the myopic direction with commercially available dominant design multifocal contact lenses. The higher add (+3.00 D induced an significantly higher effect than the +2.00 D add lens, although an increase of 1 D in add power does not correspond to the same amount of increase in RPRE.

Mechanistic modeling of ophthalmic drug delivery to the anterior chamber by eye drops and contact lenses.

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Gause, Samuel; Hsu, Kuan-Hui; Shafor, Chancellor; Dixon, Phillip; Powell, Kristin Conrad; Chauhan, Anuj

2016-07-01

Ophthalmic drug for the anterior chamber diseases are delivered into tears by either eye drops or by extended release devices placed in the eyes. The instilled drug exits the eye through various routes including tear drainage into the nose through the canaliculi and transport across various ocular membranes. Understanding the mechanisms relevant to each route can be useful in predicting the dependency of ocular bioavailability on various formulation parameters, such as drug concentration, salinity, viscosity, etc. Mathematical modeling has been developed for each of the routes and validated by comparison with experiments. The individual models can be combined into a system model to predict the fraction of the instilled drug that reaches the target. This review summarizes the individual models for the transport of drugs across the cornea and conjunctiva and the canaliculi tear drainage. It also summarizes the combined tear dynamics model that can predict the ocular bioavailability of drugs instilled as eye drops. The predictions from the individual models and the combined model are in good agreement with experimental data. Both experiments and models predict that the corneal bioavailability for drugs delivered through eye drops is less than 5% due to the small area of the cornea in comparison to the conjunctiva, and the rapid clearance of the instilled solution by tear drainage. A contact lens is a natural choice for delivering drugs to the cornea due to the placement of the contact in the immediate vicinity of the cornea. The drug released by the contact towards the cornea surface is trapped in the post lens tear film for extended duration of at least 30min allowing transport of a large portion into the cornea. The model predictions backed by in vivo animal and clinical data show that the bioavailability increases to about 50% with contact lenses. This realization has encouraged considerable research towards delivering ocular drugs by contact lenses. Commercial

Microbial contamination of contact lenses after scaling and root planing using ultrasonic scalers with and without protective eyewear: A clinical and microbiological study

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Rooh Afzha

2016-01-01

Full Text Available Background: Ultrasonic scaler is a preferential treatment modality among the clinicians. However, the aerosol/splatter generated is a concern for patients and practitioners. Therefore, the purpose of this study was to evaluate contamination of contact lenses of the dentist after scaling and root planing using ultrasonic scalers with and without protective eyewear. Materials and Methods: Thirty patients were randomly selected for scaling and root planing and divided into 2 groups of 15 each. Group A - dentist wearing contact lenses and protective eyewear. Group B - dentist wearing only contact lenses. After scaling and root planing using ultrasonic scalers, the lenses were subjected to culture and 16S rRNA (16S ribosomal RNA gene sequencing. Results: In Group A – 15 out of thirty samples were contaminated, in Group B – all the thirty samples were contaminated. Most of the samples showed Gram-positive bacteria and 5 samples were contaminated with fungi. 16S rRNA gene sequencing of forty contaminated samples showed that 31 were contaminated with Streptococcus mutans and 9 with Staphylococcus aureus. Conclusion: Keeping in mind the limitation of the study for the absence of negative control, we would like to conclude that dental practitioners should better avoid contact lenses in a dental setup because of the risk of contamination of the contact lenses from the various dental procedures which can produce aerosol/splatter and if worn, it is recommended to wear protective eyewear.

Microbiological study of therapeutic soft contact lenses used in the treatment of recurrent corneal erosion syndrome.

Science.gov (United States)

Park, Young Min; Kwon, Han Jo; Lee, Jong Soo

2015-03-01

To determine the bacteriological spectrum of the removed therapeutic soft contact lenses (TSCLs) and to establish efficacy of prophylactic antibiotics on TSCLs used for 2 weeks for treatment of patients with recurrent corneal erosion syndrome (RCES). This study included idiopathic RCES treated using highly oxygen-permeable silicone hydrogel contact lenses (CLs), and treated 4 times per day with topical tobramycin 3% for 2 weeks. After TSCLs were applied for 2 weeks, the lenses were removed with sterile forceps under which a speculum was inserted, and placed on blood agar with the inner face down. The TSCLs were analyzed for bacterial colonization, and antibiotic susceptibility tests were performed for the isolates, using disk diffusion. Of the 40 lenses analyzed, 9 (22.5%) yielded positive cultures. Staphylococcus epidermidis was the most commonly isolated microorganism; there were five methicillin-sensitive coagulase-negative staphylococci and two methicillin-resistant coagulase-negative staphylococci. Furthermore, we found two lenses that were colonized by Enterobacter gergoviae and Citrobacter freundii. All cultured bacteria showed intermediate or complete sensitivity to ciprofloxacin, tigecycline, and tobramycin. Despite bacterial colonization in 9 CLs, no clinical signs of infectious keratitis were found in any of the patients with prophylactic topical tobramycin 3%. In case of using TSCLs for 2 weeks, tobramycin or ciprofloxacin may be useful as prophylactic topical antibiotics for preventing secondary corneal infections. Considering currently growing incidence of ciprofloxacin-resistant ocular isolates, tobramycin seems to be a reasonable prophylactic topical antibiotic susceptible broad spectrum of bacteria in clinics.

Diabetes mellitus y lentes de contacto Diabetes mellitus related to use of contact lenses

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Beatriz Zozaya Aldana

2009-04-01

Full Text Available Cada día aumenta el número de diabéticos diagnosticados que demandan como método de compensación para los defectos de refracción las lentes de contacto. Debido a la escasa información que se tiene sobre el tema, dedicamos nuestro trabajo a realizar una revisión sobre la relación de estos dos temas: lentes de contacto y diabetes, con el justo ánimo de brindar una atención más completa a nuestros pacientes.Every day increases the figure of diagnosed diabetic patients requiring a compensatory method for refraction defects the use of contact lenses. Due to the non-available information on this matter, this paper is aimed to make a review on relation between these two topics: contact lenses and diabetes to offer a more complete care to our patients.

Antimicrobial Efficacy of Multipurpose Disinfecting Solutions in the Presence of Contact Lenses and Lens Cases.

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Gabriel, Manal M; McAnally, Cindy; Bartell, John

2018-03-01

The aim of this study was to use antimicrobial efficacy endpoint methodology to determine compatibility of multipurpose disinfecting solutions (MPSs), lens cases, and hydrogel lenses for disinfection (AEEMC) against International Organization for Standardization (ISO)-specified microorganisms and clinical ocular isolates of Stenotrophomonas maltophilia. Six MPSs (PQ/Aldox 1, 2, and 3; PQ/Alexidine; PQ/PHMB; and PHMB) were challenged against ISO-specified microorganisms and S. maltophilia using the AEEMC test. AEEMC tests were performed with and without balafilcon A, etafilcon A, and senofilcon A lenses in lens cases with organic soil. Exposure times included disinfection time (DT) and 24 hr. Additionally, all six MPSs were challenged with two strains of S. maltophilia, based on the ISO Stand-alone test. The efficacy against bacteria for PQ/Aldox and PQ/Alexidine MPSs was not diminished by the presence of lenses. The efficacy of PQ/PHMB and PHMB MPSs against Serratia marcescens was significantly reduced compared with the no-lens control at DT for at least one lens type. The PHMB MPS with lenses present also demonstrated reduced efficacy against Staphylococcus aureus at DT versus the control. PQ/Aldox MPSs retained activity against Fusarium solani with lenses present; however, all other test MPSs demonstrated reduced F. solani efficacy at DT with lenses present. With lenses, all MPSs showed reduced efficacy against Candida albicans. AEEMC antimicrobial efficacy test results vary based on challenge microorganism, contact lenses, and MPS biocide systems. This study highlights the importance of evaluating MPSs for compatibility with lenses and lens cases.

Clinical study of two kinds of bandage contact lenses after laser-assisted subepithelial keratectomy

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Wan-Ting Zhang

2016-07-01

Full Text Available AIM: To investigate the clinical safety and effectiveness of the two kind of bandage contact lenses: Senofilcon A(Johnson & Johnson Acuvue Oasysand Balafilcon A(Bausch& Lomb pure visionafter laser-assisted subepithelial keratectomy(LASEK. METHODS: Thirty-eight patients(76 eyeswho had undergone the LASEK were divided into two groups. One group of patients wore Balafilcon A, the other group of patients fitted with Senofilcon A. The lenses were worn continuously for 7d. This was a seven-day experience and the patients scored for the symptom of the eyes(sore eyes, foreign body sensation and tearingon the third day and the seventh day. Both of the two groups of patients taken off the soft contact lens on the seventh day and let their vision and corneal staining checked.RESULTS: The symptoms of eye sore and tearing of the two groups patients were different. The patients who wore the Senofilcon A were better. The pain of eyes were also different at 3 and 7d after surgeries(Z=-4.146, P=0.000; Z=-2.814, P=0.005. The difference on tearing between the two groups at 3 and 7d after surgeries were significant(Z=-2.309, P=0.021; Z=-3.276, P=0.001. There was no difference on sensation of dryness between the two groups at 3 and 7d after surgeries(Z=-0.447, P=0.655; Z=-0.966, P=0.334. After the lenses were taken off, the visual acuity of patients wearing Senofilcon A was better(t=3.800, P=0.001; corneal staining showed limited spots in 1-2 quadrants with significant difference(Z=-2.384,P=0.017. CONCLUSION: The Senofilcon A(Johnson & Johnson Acuvue Oasysand Balafilcon A(Bausch& Lomb pure visionbandage contact lenses are safe and effective after LASEK, and the former is better than the latter in epithelial regeneration.

Evaluation of the safety and efficacy of therapeutic bandage contact lenses on post-cataract surgery patients.

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Shi, Dan-Na; Song, Hang; Ding, Tong; Qiu, Wei-Qiang; Wang, Wei

2018-01-01

To evaluate the safety of therapeutic bandage contact lens for post-cataract surgery patients and to illustrate its efficacy on post-operative comfort and tear-film stability. A total of 40 participants were recruited and randomly divided into two groups. Group one was instructed to wear bandage contact lenses for a week and use antibiotic eye drops for a month since the first day after surgery. Group two received sub-conjunctival injection of tobramycin and was asked to wear eye pads on the first day after surgery and then were instructed to use antibiotic eye drops as the first group did. Ocular surface disease index (OSDI) questionnaire, slit-lamp microscope examination of tear break-up time (TBUT), corneal fluorescein score (CFS), tear meniscus height (TMH) together with anterior segment optical coherence tomography (AS-OCT) and corneal topography were evaluated preoperatively and postoperatively. The subjective feeling ( P =0.004), TBUT ( P <0.001) and TMH ( P =0.02) post-surgery had improved in patients who used bandage contact lenses compared with those who did not at 1wk post-surgery. Until three month postoperatively, the comfort degree ( P =0.004) and TMH ( P =0.01) of group two were still worse than group one. Moreover, TBUT ( P <0.001) and CFS ( P =0.004) of the group with eye pads got worse than the results before, whereas the group with bandage contact lenses recovered to normal. None of these patients had infections or other complications. Wearing therapeutic bandage contact lens after cataract surgery, compared with traditional eye-pads, is a safe method to improve tear-film stability and reduce post-operative discomfort without hindering corneal incision recovery.

Applicability of contact angle techniques used in the analysis of contact lenses, part 1: comparative methodologies.

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Campbell, Darren; Carnell, Sarah Maria; Eden, Russell John

2013-05-01

Contact angle, as a representative measure of surface wettability, is often employed to interpret contact lens surface properties. The literature is often contradictory and can lead to confusion. This literature review is part of a series regarding the analysis of hydrogel contact lenses using contact angle techniques. Here we present an overview of contact angle terminology, methodology, and analysis. Having discussed this background material, subsequent parts of the series will discuss the analysis of contact lens contact angles and evaluate differences in published laboratory results. The concepts of contact angle, wettability and wetting are presented as an introduction. Contact angle hysteresis is outlined and highlights the advantages in using dynamic analytical techniques over static methods. The surface free energy of a material illustrates how contact angle analysis is capable of providing supplementary surface characterization. Although single values are able to distinguish individual material differences, surface free energy and dynamic methods provide an improved understanding of material behavior. The frequently used sessile drop, captive bubble, and Wilhelmy plate techniques are discussed. Their use as both dynamic and static methods, along with the advantages and disadvantages of each technique, is explained. No single contact angle technique fully characterizes the wettability of a material surface, and the application of complimenting methods allows increased characterization. At present, there is not an ISO standard method designed for soft materials. It is important that each contact angle technique has a standard protocol, as small protocol differences between laboratories often contribute to a variety of published data that are not easily comparable.

Robert Mandell: a pioneer and giant in the art and science of contact lenses.

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Polse, Kenneth A

2008-10-01

Robert B. Mandell is the quintessential modern clinical scientist. Over his long academic career, he has pioneered many advances in contact lens practice, ranging from a more complete understanding of corneal shape to the effects of contact lenses on corneal health. His classic text, Contact Lens Practice, first published in 1965, was reprinted 14 times in four editions up to 1988. Mandell's contributions to the advancement of the profession of optometry have always been characterized by a genuine concern for the patient and a steadfast belief that his research must have relevance to the practice of optometry.

Computational Sensing of Staphylococcus aureus on Contact Lenses Using 3D Imaging of Curved Surfaces and Machine Learning.

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Veli, Muhammed; Ozcan, Aydogan

2018-03-27

We present a cost-effective and portable platform based on contact lenses for noninvasively detecting Staphylococcus aureus, which is part of the human ocular microbiome and resides on the cornea and conjunctiva. Using S. aureus-specific antibodies and a surface chemistry protocol that is compatible with human tears, contact lenses are designed to specifically capture S. aureus. After the bacteria capture on the lens and right before its imaging, the captured bacteria are tagged with surface-functionalized polystyrene microparticles. These microbeads provide sufficient signal-to-noise ratio for the quantification of the captured bacteria on the contact lens, without any fluorescent labels, by 3D imaging of the curved surface of each lens using only one hologram taken with a lens-free on-chip microscope. After the 3D surface of the contact lens is computationally reconstructed using rotational field transformations and holographic digital focusing, a machine learning algorithm is employed to automatically count the number of beads on the lens surface, revealing the count of the captured bacteria. To demonstrate its proof-of-concept, we created a field-portable and cost-effective holographic microscope, which weighs 77 g, controlled by a laptop. Using daily contact lenses that are spiked with bacteria, we demonstrated that this computational sensing platform provides a detection limit of ∼16 bacteria/μL. This contact-lens-based wearable sensor can be broadly applicable to detect various bacteria, viruses, and analytes in tears using a cost-effective and portable computational imager that might be used even at home by consumers.

Evaluation of the safety and efficacy of therapeutic bandage contact lenses on post-cataract surgery patients

Directory of Open Access Journals (Sweden)

Dan-Na Shi

2018-02-01

Full Text Available AIM: To evaluate the safety of therapeutic bandage contact lens for post-cataract surgery patients and to illustrate its efficacy on post-operative comfort and tear-film stability. METHODS: A total of 40 participants were recruited and randomly divided into two groups. Group one was instructed to wear bandage contact lenses for a week and use antibiotic eye drops for a month since the first day after surgery. Group two received sub-conjunctival injection of tobramycin and was asked to wear eye pads on the first day after surgery and then were instructed to use antibiotic eye drops as the first group did. Ocular surface disease index (OSDI questionnaire, slit-lamp microscope examination of tear break-up time (TBUT, corneal fluorescein score (CFS, tear meniscus height (TMH together with anterior segment optical coherence tomography (AS-OCT and corneal topography were evaluated preoperatively and postoperatively. RESULTS: The subjective feeling (P=0.004, TBUT (P<0.001 and TMH (P=0.02 post-surgery had improved in patients who used bandage contact lenses compared with those who did not at 1wk post-surgery. Until three month postoperatively, the comfort degree (P=0.004 and TMH (P=0.01 of group two were still worse than group one. Moreover, TBUT (P<0.001 and CFS (P=0.004 of the group with eye pads got worse than the results before, whereas the group with bandage contact lenses recovered to normal. None of these patients had infections or other complications. CONCLUSION: Wearing therapeutic bandage contact lens after cataract surgery, compared with traditional eye-pads, is a safe method to improve tear-film stability and reduce post-operative discomfort without hindering corneal incision recovery.

25G compared with 20G vitrectomy under Resight non-contact wide-angle lenses for Terson syndrome.

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Mao, Xinbang; You, Zhipeng

2017-08-01

The aim of the present study was to compare the effectiveness of 25G vitrectomy to standard 20G vitrectomy for treatment of Terson syndrome under Resight non-contact wide-angle lenses. This was a case-control study of 20 patients with Terson syndrome (study group) that underwent 25G vitrectomy under Resight non-contact wide-angle lenses, with those of 20 matched patients that underwent 20G vitrectomy (control group). Medical records were reviewed from between July 2011 and October 2013. Data included results of the Early Treatment Diabetic Retinopathy Study examination, ophthalmology B-scan ultrasonography and fundus photography. The mean age, follow-up time, the preoperative visual acuity of LogMAR and the preoperative intraocular pressure (IOP) were all comparable in the two groups (all P>0.05). There were statistically significant differences in postoperative visual acuity of LogMAR compared with preoperative visual acuity (Pcontact wide-angle lenses can achieve a significantly shorter operative time and lower post-operative IOP compared with 20G Vitrectomy.

Bacterial transmission from lens storage cases to contact lenses - Effects of lens care solutions and silver impregnation of cases

NARCIS (Netherlands)

Vermeltfoort, Pit B. J.; Hooymans, Johanna M. M.; Busscher, Henk J.; van der Mei, Henny C.

2008-01-01

The killing efficacies of multipurpose lens care solutions on planktonic and biofilm bacteria grown in polypropylene contact lens storage cases with and without silver impregnation and effects on bacterial transmission from storage cases to silicone hydrogel contact lenses were investigated. For

Efficacy of highly hydrophilic soft contact lenses for persistent corneal epithelial defects after anterior segment surgery

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Zhi-Wei Peng

2015-02-01

Full Text Available AIM:To investigate the efficacy of highly hydrophilic soft contact lenses for persistent corneal epithelial defects.METHODS:In this retrospective case analysis, 28 patients(28 eyeswith persistent corneal epithelial defects after anterior segment surgery from January 2011 to June 2013 in our hospital were reviewed. After regular treatment for at least 2wk, the persistent corneal epithelial defects were treated with highly hydrophilic soft contact lenses, until the corneal epithelial healing. Continued to wear the same lens no more than 3wk, or in need of replacement the new one. All cases were followed up for 6mo. Key indicators of corneal epithelial healling, corneal fluorescein staining and ocular symptoms improvement were observed.RESULTS: Twenty-one eyes were cured(75.00%, markedly effective in 5 eyes(17.86%, effective in 2 eyes(7.14%, no invalid cases, the total efficiency of 100.00%. Ocular symptoms of 25 cases(89.29%relieved within 2d, the rest 3 cases(10.71%relieved within 1wk. The corneal epithelial of 6 cases(21.43%repaired in 3wk, 13 cases(46.43%in 6wk, 7 cases(25.00%in 9wk, 2 cases(7.14%over 12wk. There were no signs of secondary infection. And no evidence of recurrence in 6mo. CONCLUSION: Highly hydrophilic soft contact lenses could repair persistent corneal epithelial defects after anterior segment surgery significantly, while quickly and effectively relieve a variety of ocular irritation.

Investigation of biofilm formation on contact eye lenses caused by methicillin resistant Staphylococcus aureus.

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Khalil, M A; Sonbol, F I

2014-01-01

The objective was to investigate the biofilm-forming capacity of methicillin resistant Staphylococcus aureus (MRSA) isolated from eye lenses of infected patients. A total of 32 MRSA isolated from contact lenses of patients with ocular infections were screened for their biofilm-forming capacity using tube method (TM), Congo red agar (CRA), and microtiter plate (MtP) methods. The effect of some stress factor on the biofilm formation was studied. The biofilm-forming related genes, icaA, icaD and 10 microbial surface components that recognize adhesive matrix molecule (MSCRAMM), of the selected MRSA were also detected using polymerase chain reaction. Of 32 MRSA isolates, 34.37%, 59.37%, and 81.25% showed positive results using CRA, TM or MtP, respectively. Biofilm production was found to be reduced in the presence of ethanol or ethylenediaminetetraacetic acid and at extreme pH values. On the other hand, glucose or heparin leads to a concentration dependent increase of biofilm production by the isolates. The selected biofilm producing MRSA isolate was found to harbor the icaA, icaD and up to nine of 10 tested MSCRAMM genes, whereas the selected non biofilm producing MRSA isolate did not carry any of the tested genes. The MtP method was found to be the most effective phenotypic screening method for detection of biofilm formation by MRSA. Furthermore, the molecular approach should be taken into consideration for the rapid and correct diagnosis of virulent bacteria associated with contact eye lenses.

Microbial adhesion to silicone hydrogel lenses: a review.

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Willcox, Mark D P

2013-01-01

Microbial adhesion to contact lenses is believed to be one of the initiating events in the formation of many corneal infiltrative events, including microbial keratitis, that occur during contact lens wear. The advent of silicone hydrogel lenses has not reduced the incidence of these events. This may partly be related to the ability of microbes to adhere to these lenses. The aim of this study was to review the published literature on microbial adhesion to contact lenses, focusing on adhesion to silicone hydrogel lenses. The literature on microbial adhesion to contact lenses was searched, along with associated literature on adverse events that occur during contact lens wear. Particular reference was paid to the years 1995 through 2012 because this encompasses the time when the first clinical trials of silicone hydrogel lenses were reported, and their commercial availability and the publication of epidemiology studies on adverse events were studied. In vitro studies of bacterial adhesion to unworn silicone hydrogel lens have shown that generally, bacteria adhere to these lenses in greater numbers than to the hydroxyethyl methacrylate-based soft lenses. Lens wear has different effects on microbial adhesion, and this is dependent on the type of lens and microbial species/genera that is studied. Biofilms that can be formed on any lens type tend to protect the bacteria and fungi from the effects on disinfectants. Fungal hyphae can penetrate the surface of most types of lenses. Acanthamoeba adhere in greater numbers to first-generation silicone hydrogel lenses compared with the second-generation or hydroxyethyl methacrylate-based soft lenses. Microbial adhesion to silicone hydrogel lenses occurs and is associated with the production of corneal infiltrative events during lens wear.

Comparison Between Bandage Contact Lenses and Pressure Patching on the Erosion Area and Pain Scale in Patients With Corneal Erosion.

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Triharpini, Ni Nyoman; Gede Jayanegara, I Wayan; Handayani, Ariesanti Tri; Widiana, I Gde Raka

2015-01-01

Corneal erosion is common in eye emergency cases. Extensive corneal erosions result in severe pain and prolonged healing time. This study aimed to compare bandage contact lenses with pressure patching in terms of reducing the size of the erosion area, pain scale in patients with corneal erosion and its complications. A randomized open-label clinical trial was conducted. Subjects with mechanical corneal erosion were selected to use either bandage contact lenses or pressure patching. All subjects received antibiotic eye drops and 0.5% tropicamide eye drops. Evaluations were done 24 and 72 hours after treatment. The size of the corneal erosion area, pain scale, and complications were assessed. A total of 32 eyes (16 eyes in each group) were studied. The change in the size of the corneal erosion area was greater in the bandage contact lens group than in the pressure patching group, although there was no significant difference. In the bandage contact lens group, 56.25% of the eyes were healed at 24 hours and 43.75% were healed at 72 hours. In the pressure patching group, 62.50% were healed at 24 hours and 12.50% were healed at 72 hours. The change in pain scale was significantly greater in the bandage contact lens group than in the pressure patching group. No complications were found in both groups. Bandage contact lenses are an effective alternative to treating mechanical corneal erosion because of their effect in reducing pain without causing any complications.

Extended latanoprost release from commercial contact lenses: in vitro studies using corneal models.

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Saman Mohammadi

Full Text Available In this study, we compared, for the first time, the release of a 432 kDa prostaglandin F2a analogue drug, Latanoprost, from commercially available contact lenses using in vitro models with corneal epithelial cells. Conventional polyHEMA-based and silicone hydrogel soft contact lenses were soaked in drug solution (131 μg = ml solution in phosphate buffered saline. The drug release from the contact lens material and its diffusion through three in vitro models was studied. The three in vitro models consisted of a polyethylene terephthalate (PET membrane without corneal epithelial cells, a PET membrane with a monolayer of human corneal epithelial cells (HCEC, and a PET membrane with stratified HCEC. In the cell-based in vitro corneal epithelium models, a zero order release was obtained with the silicone hydrogel materials (linear for the duration of the experiment whereby, after 48 hours, between 4 to 6 μg of latanoprost (an amount well within the range of the prescribed daily dose for glaucoma patients was released. In the absence of cells, a significantly lower amount of drug, between 0.3 to 0.5 μg, was released, (p <0:001. The difference observed in release from the hydrogel lens materials in the presence and absence of cells emphasizes the importance of using an in vitro corneal model that is more representative of the physiological conditions in the eye to more adequately characterize ophthalmic drug delivery materials. Our results demonstrate how in vitro models with corneal epithelial cells may allow better prediction of in vivo release. It also highlights the potential of drug-soaked silicone hydrogel contact lens materials for drug delivery purposes.

The role of contact lenses and ocular TRAUMA in determining Acanthamoeba Keratitis: a case-control study in Italy.

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Elena Pacella

2012-03-01

Full Text Available

Abstract:
Background: acanthamoeba keratitis (a.k. is a rare secondary infection due to acanthamoeba (a invading the cornea. cofactors of risk may include TrauMa and contact lenses (cL. The objectives of this observational study are to evaluate the occurrence of a.k. in patients accessing the department of Special Senses of the Teaching Hospital “Policlinico umberto I" of rome with ocular infections dur- ing the period from 2005 to 2011, and the role played by risk factors which included contact lenses, TrauMa, sex and age.
Methods: a case-control study involving 714 subjects was conducted (350 male and 364 female. all of the patients underwent a thorough ocular examination with confocal microscopy and a review of their medical history to outline relevant variables (contact lens and TrauMa. Statistical analysis calculated the frequency distribution and the odds ratio (or (95%cI for the risk factors "contact lenses" (cL and "TrauMa". The odds ratio (95%cI was adjusted for age and sex trough Logistic regression. Results: out of 714 patients, 11 patients (7 male and 4 female with a mean age of 34.09 years (19 to 51 years old were found to be affected by a.k. The age group most afflicted ranged from 30 to 51 years old. Statistical analysis produced a crude or equal to 17.68 (95%cI 2.25-138.89 for cL-a.k. and or equal to 7.71 (95%cI 0.89-66.75 for ocular TrauMa.-a.k. Logistic regression performed to adjust or for age and sex showed the following values, respectively: or*=82.54 (95%cI 3.04-2239.58 and or*=11.52 (95%cI 1.19-111.76.
Conclusions: the data highlights an increase in a.k. cases during the 6 year study period. The association between this pathology and the use of contact lenses and/or TrauMa has been statisti- cally proven. The strength of this association increases when the odds ratio (or* is adjusted for the confounding risk factors of

Focusing on Contact Lens Safety

Science.gov (United States)

... their practices. Decorative contacts (also called “costume,” colored,” “fashion,” or “plano” contacts). The FDA has often warned ... Lenses Decorative Contact Lenses Hydrogen Peroxide Solution Related Consumer Updates 'Colored' and Decorative Contact Lenses: A Prescription ...

Accuracy of intraocular pressure measurements in dogs using two different tonometers and plano therapeutic soft contact lenses.

Science.gov (United States)

Ahn, Jeong-Taek; Jeong, Man-Bok; Park, Young-Woo; Kim, Se-Eun; Ahn, Jae-Sang; Lee, Yes-Ran; Lee, Eui-Ri; Seo, Kangmoon

2012-03-01

To compare and evaluate the accuracy of intraocular pressure (IOP) measured through a therapeutic contact lens, using applanation (TonoPen XL(®)) and rebound (TonoVet(®)) tonometers in enucleated dog eyes. A total of 30 enucleated eyes from 15 beagle dogs. To measure accurate IOP, the anterior chamber of each enucleated eye was cannulated with two 26-gauge needles and two polyethylene tubes were connected vertically to an adjustable reservoir bag of normal saline and a pressure transducer. IOP was measured by the TonoPen XL(®) followed by the TonoVet(®) without a contact lens. After a contact lens was applied to the cornea, IOP was re-measured in the same order. Three consecutive IOP measurements were performed using both tonometers. Without the contact lens, the IOP values obtained by both tonometers correlated well according to the regression analysis (TonoVet(®): γ(2) = 0.98, TonoPen XL(®): γ(2) = 0.97, P contact lens was applied to the cornea. Bland-Altman analysis was used to determine the lower and upper limits of agreement (TonoVet(®): -29.7 and +21.1 mmHg, TonoPen XL(®): -3.9 and +3.6 mmHg) between the two devices. This study suggests that the TonoPen XL(®) is a useful tonometer for dogs wearing therapeutic contact lenses, and importantly, contact lenses would not need to be removed prior to IOP measurement. © 2012 American College of Veterinary Ophthalmologists.

Dynamic simulation of the effect of soft toric contact lenses movement on retinal image quality.

Science.gov (United States)

Niu, Yafei; Sarver, Edwin J; Stevenson, Scott B; Marsack, Jason D; Parker, Katrina E; Applegate, Raymond A

2008-04-01

To report the development of a tool designed to dynamically simulate the effect of soft toric contact lens movement on retinal image quality, initial findings on three eyes, and the next steps to be taken to improve the utility of the tool. Three eyes of two subjects wearing soft toric contact lenses were cyclopleged with 1% cyclopentolate and 2.5% phenylephrine. Four hundred wavefront aberration measurements over a 5-mm pupil were recorded during soft contact lens wear at 30 Hz using a complete ophthalmic analysis system aberrometer. Each wavefront error measurement was input into Visual Optics Laboratory (version 7.15, Sarver and Associates, Inc.) to generate a retinal simulation of a high contrast log MAR visual acuity chart. The individual simulations were combined into a single dynamic movie using a custom MatLab PsychToolbox program. Visual acuity was measured for each eye reading the movie with best cycloplegic spectacle correction through a 3-mm artificial pupil to minimize the influence of the eyes' uncorrected aberrations. Comparison of the simulated acuity was made to values recorded while the subject read unaberrated charts with contact lenses through a 5-mm artificial pupil. For one study eye, average acuity was the same as the natural contact lens viewing condition. For the other two study eyes visual acuity of the best simulation was more than one line worse than natural viewing conditions. Dynamic simulation of retinal image quality, although not yet perfect, is a promising technique for visually illustrating the optical effects on image quality because of the movements of alignment-sensitive corrections.

The Long-Term Effects of Silicone Hydrogel Contact Lenses on the Ocular Surface and Tear Function Tests

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Yelda Yıldız Taşcı

2014-05-01

Full Text Available Objectives: To evaluate the effects of three different silicone hydrogel contact lenses, i.e. Balafilcon A (Pure Vision, Bausch & Lomb, Senofilcon A (Acuvue Oasys, Johnson & Johnson, and Confilcon A (Biofinity, CooperVision, on ocular surface after one, three, and sıx months of wear. Materials and Methods: Silicone hydrogel contact lenses (SHCL were fitted to 58 patients (Balafilcon A to 40 eyes: Group 1, Senofilcon A to 42 eyes: Group 2, and Confilcon A to 34 eyes: Group 3 who have not used any contact lenses before. All groups were graded according to the Cornea and Contact Lens Research Unit’s grading score, and were performed ocular surface disease index scoring (OSDI, tear break-up time (BUT, and Schirmer 1 test. Results: The mean age was 22.45±5.96, 20.76±3.70, 21.00±3.84 years in Groups 1,2, and 3, respectively (p>0.05. While the increase in papillary hypertrophy as well as palpebral and bulbar hyperemia at 1st month in Group 1 and at 6th month at Group 2 were significant, there were no change in Group 3 with the use of SHCL (p0.05. In Group 3, the Schirmer test was lower than in Groups 1 and 2, which was statistically significant (p=0.048, p=0.003. Conclusion: Factors like lens material, modulus, the presence of an internal wetting agent, and water content play an important role in the effects of SHCL on the ocular surface. In this study, it is demonstrated that SHCL does not cause clinically significant dry eye. (Turk J Ophthalmol 2014; 44: 201-6

Fabricating customized hydrogel contact lens

Science.gov (United States)

Childs, Andre; Li, Hao; Lewittes, Daniella M.; Dong, Biqin; Liu, Wenzhong; Shu, Xiao; Sun, Cheng; Zhang, Hao F.

2016-10-01

Contact lenses are increasingly used in laboratories for in vivo animal retinal imaging and pre-clinical studies. The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited. Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1.42 to 1.45 in the spectra range from 400 nm to 800 nm. The Young’s modulus (1.47 MPa) and hydrophobicity (with a sessile drop contact angle of 40.5°) have also been characterized experimentally. Retinal imaging using optical coherence tomography in rats wearing our customized contact lenses has the quality comparable to the control case without the contact lens. Our method could significantly reduce the cost and the lead time for fabricating soft contact lenses with customized shapes, and benefit the laboratorial-used contact lenses in pre-clinical studies.

Microcyst response to high Dk/t silicone hydrogel contact lenses.

Science.gov (United States)

Keay, L; Sweeney, D F; Jalbert, I; Skotnitsky, C; Holden, B A

2000-11-01

To investigate the microcyst response to extended wear (EW) with high oxygen transmissible (Dk/t) silicone hydrogel lenses. Microcysts were monitored for 12 months in subjects wearing low Dk/t hydrogel lenses on a 6-night EW schedule or high Dk/t hydrogel lenses on a 30-night EW schedule. Subjects wearing low Dk/t lenses transferred to the high Dk/t EW lenses and schedule after 12 months and were monitored for a further 6 months. The mean number of microcysts did not deviate from baseline in the high Dk/t group. Microcysts in the low Dk/t group increased over 12 months, and more microcysts were observed in low Dk/t lens wearers compared with high Dk/t lens wearers after 3 months. Microcysts increased in 50% of subjects 1 week after transfer to high Dk/t lenses and returned to baseline levels seen with high Dk/t lens wear within 3 months. EW with high Dk/t silicone hydrogel lenses did not cause an increase in microcyst numbers. It is not necessary to discontinue lens wear with patients who transfer from low to high Dk/t lenses because the increase in microcysts is transitory. This result has implications for practitioners when fitting and assessing the success of high Dk/t hydrogel lenses.

A comparison of in-air and in-saline focimeter measurement of the back vertex power of spherical soft contact lenses.

Science.gov (United States)

Pearson, Richard M; Evans, Bruce J W

2012-11-01

To compare the repeatability and validity of measurements of the back vertex power (BVP) of spherical soft contact lenses made in-air using the method specified in the International Standard (ISO 18369-3:2006) with the corresponding values when BVP was calculated from measurements made using a wet cell and focimeter method that is not approved by this Standard. The BVP of 20 hydrogel and 20 silicone hydrogel lenses, with labelled powers ranging from +8.00 to -12.00 D, were measured with a focimeter by two operators on two occasions in-air in accordance with the relevant International Standard. Equivalent sets of measurements were made with the lenses immersed in-saline within a wet cell and their BVPs in-air were calculated. The validity of each method was assessed by comparing their results with an instrument that used the Hartmann method. The reliability results were generally a little better for the in-saline measurements than for the in-air measurements, although all reliability data demonstrated absolute values of mean errors (inter-operator and inter-session) that were power of high plus and high minus lenses compared with the Hartmann instrument) and possibly a more complex relationship for the in-saline data. The 95% limits of agreement indicate better agreement for the in-saline validity data (-0.55 to +0.48 D for hydrogel lenses and -0.42 to +0.54 D for silicone hydrogel lenses) than those obtained in-air (-0.64 to +0.68 D for hydrogel lenses and -0.57 to +0.44 D for silicone hydrogel lenses). Using equipment readily available in a clinical setting, the wet cell method of measurement of the BVP of spherical soft contact lenses has been shown to provide results for reliability and validity that were at least as good as those obtained with the in-air method approved by the International Standard. Ophthalmic & Physiological Optics © 2012 The College of Optometrists.

Reliability of power profiles measured on NIMO TR1504 (Lambda-X) and effects of lens decentration for single vision, bifocal and multifocal contact lenses.

Science.gov (United States)

Kim, Eon; Bakaraju, Ravi C; Ehrmann, Klaus

2016-01-01

To evaluate the repeatability of power profiles measured on NIMO TR1504 (Lambda-X, Belgium) and investigate the effects of lens decentration on the power profiles for single vision (SV), bifocal (BF) and multifocal (MF) contact lenses. Accuracy of the sphere power was evaluated using single vision BK-7 calibration glass lenses of six minus and six plus powers. Three SV and four BF/MF contact lenses - three lenses each, were measured five times to calculate the coefficients of repeatability (COR) of the instrument. The COR was computed for each chord position, lens design, prescription power and operator. One lens from each type was measured with a deliberate decentration up to ±0.5mm in 0.1mm steps. For all lenses, the COR varied across different regions of the half-chord position. In general, SV lenses showed lower COR compared to the BF/MF group lenses. There were no noticeable trends of COR between prescription powers for SV and BF/MF lenses. The shape of the power profiles was not affected when lenses were deliberately decentered for all SV and PureVision MF lenses. However, for Acuvue BF lenses, the peak to trough amplitude of the power profiles flattened up to 1.00D. The COR across the half-chord of the optic zone diameter was mostly within clinical relevance except for the central 0.5mm half-chord position. COR were dependent on the lens type, whereby BF/MF group produced higher COR than SV lenses. The effects of deliberate decentration on the shape of power profiles were pronounced for lenses where the profiles had sharp transitions of power. Copyright © 2015 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Colored Contact Lens Dangers

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Full Text Available ... Cleveland. "This is far from the truth." Real People, Real Problems with Colored Contact Lenses Julian: Teenager ... the lenses. Never share contact lenses with another person. Get follow up exams with your eye care ...

Clinical evaluation of a computerized topography software method for fitting rigid gas permeable contact lenses.

Science.gov (United States)

Szczotka, L B; Capretta, D M; Lass, J H

1994-10-01

Computerized videokeratoscope software programs now have the ability to assist in the design of rigid gas permeable (RGP) contact lenses and simulate fluorescein patterns. We evaluated the performance of Computed Anatomy's Topographic Modeling System (TMS-1) and its Contact Lens Fitting Program (version 1.41) in fitting RGP lenses in 31 subjects. Computerized topographic analysis, balanced manifest refraction, slit lamp examination, and keratometry were performed. Initial lens parameters were ordered according to manufacturer's programmed recommendations for base curve, power, lens diameter, optic zone diameter, and edge lift. Final lens parameters were based on clinical performance. Lenses were recorded for base curve changes of 0.1 mm or more, power alterations of +/- 0.50 D or more, or for any alteration in diameter/optic zone. Twenty-seven patients were analyzed for all five recommended parameters. Thirteen of 27 patients (48%) required no parameter changes. Nine of 27 patients (33%) required one parameter change, four of 27 patients (15%) required two parameter changes, and one patient (4%) needed three parameters altered. The most prevalent change was a power alteration, required in nine of 27 patients (33%); however, comparisons of all initial to final parameters showed no statistically significant differences. Comparison of initial base curves to that which would have been chosen via standard keratometry also showed no significant difference. This study found the TMS-1 default lens recommendations to be clinically unacceptable. This system, however, could be an alternative method of initial lens selection if used to titrate a fit or if software enhancements are incorporated to account for lens movement and flexure.

Drug loading optimization and extended drug delivery of corticoids from pHEMA based soft contact lenses hydrogels via chemical and microstructural modifications.

Science.gov (United States)

García-Millán, Eva; Koprivnik, Sandra; Otero-Espinar, Francisco Javier

2015-06-20

This paper proposes an approach to improve drug loading capacity and release properties of poly(2-hydroxyethyl methacrylate) (p(HEMA)) soft contact lenses based on the optimization of the hydrogel composition and microstructural modifications using water during the polymerization process. P(HEMA) based soft contact lenses were prepared by thermal or photopolymerization of 2-hydroxyethyl methacrylate (HEMA) solutions containing ethylene glycol di-methacrylate as crosslinker and different proportions of N-vinyl-2-pyrrolidone (NVP) or methacrylic acid (MA) as co-monomers. Transmittance, water uptake, swelling, microstructure, drug absorption isotherms and in vitro release were characterized using triamcinolone acetonide (TA) as model drug. Best drug loading ratios were obtained with lenses containing the highest amount (200 mM) of MA. Incorporation of 40% V/V of water during the polymerization increases the hydrogel porosity giving a better drug loading capacity. In vitro TA release kinetics shows that MA hydrogels released the drug significantly faster than NVP-hydrogels. Drug release was found to be diffusion controlled and kinetics was shown to be reproducible after consecutive drug loading/release processes. Results of p(HEMA) based soft contact lenses copolymerized with ethylene glycol dimethacrylate (EGDMA) and different co-monomers could be a good alternative to optimize the loading and ocular drug delivery of this corticosteroid drug. Copyright © 2015. Published by Elsevier B.V.

Colored Contact Lens Dangers

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Full Text Available ... Get follow up exams with your eye care provider. If you notice redness, swelling, excessive discharge, pain or discomfort from wearing contact lenses, remove the lenses and seek immediate medical attention from an ophthalmologist. Related resources: Learn how to properly care for contact lenses . ...

Contact Lens Risks

Science.gov (United States)

... There is a risk of eye infection from bacteria in swimming pool water, hot tubs, lakes and the ocean Replace your contact lens storage case every 3 months or as directed by your eye care professional. Other Risks of Contact Lenses Other risks of contact lenses include pink eye ( ...

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.

Colored Contact Lens Dangers

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Full Text Available ... One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume ... use of colored contact lenses , from the U.S. Food and Drug Administration (FDA). Are the colored lenses ...

Colored Contact Lens Dangers

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Full Text Available ... eye-care team . Consumer warning about the improper use of colored contact lenses , from the U.S. Food and Drug Administration (FDA). Are the colored lenses you are considering buying approved by the FDA? Check the FDA's database of approved contact lenses . Related Stories Prevent Infection ...

The effect of octylglucoside and sodium cholate in Staphylococcus epidermidis and Pseudomonas aeruginosa adhesion to soft contact lenses.

Science.gov (United States)

Santos, Lívia; Rodrigues, Diana; Lira, Madalena; Oliveira, Rosario; Real Oliveira, M Elisabete C D; Vilar, Eva Yebra-Pimentel; Azeredo, Joana

2007-05-01

In this study, the effect of the natural surfactants octylglucoside and sodium cholate in inhibiting Staphylococcus epidermidis and Pseudomonas aeruginosa adhesion to conventional and silicone-hydrogel contact lenses (CL) was assessed. Hydrophobicity was also evaluated to conditioned and nonconditioned CL. The inhibiting effect of the tested surfactants was determined through "in vitro" adhesion studies to conditioned and nonconditioned CL followed by image acquisition and cell enumeration. Hydrophobicity was evaluated through contact angle measurements using the advancing type technique on air. Sodium cholate exhibits a very low capability to inhibit microbial adhesion. Conversely, octylglucoside effectively inhibited microbial adhesion in both types of lenses. This surfactant exhibited an even greater performance than a multipurpose lens care solution used as control. Octylglucoside was the only tested surfactant able to lower the hydrophobicity of all CL, which can explain its high performance. The results obtained in this study point out the potential of octylglucoside as a conditioning agent to prevent microbial colonization.

Fimbrolide-coated antimicrobial lenses: their in vitro and in vivo effects.

Science.gov (United States)

Zhu, Hua; Kumar, Ajay; Ozkan, Jerome; Bandara, Rani; Ding, Aidong; Perera, Indrani; Steinberg, Peter; Kumar, Naresh; Lao, William; Griesser, Stefani S; Britcher, Leanne; Griesser, Hans J; Willcox, Mark D P

2008-05-01

To examine the ability of contact lenses coated with fimbrolides, inhibitors of bacterial quorum sensing, to prevent microbial adhesion and their safety during short-term clinical assessment. A fimbrolide was covalently attached to commercially available high Dk contact lenses. Subsequently Pseudomonas aeruginosa, Staphylococcus aureus, Serratia marcescens, or Acanthamoeba sp. were added to the lenses and control uncoated contact lenses. Lenses plus microbes were incubated for 24 h, then washed thoroughly to remove non-adherent microbes. Lenses were macerated and resulting slurry plated onto agar plates. After appropriate incubation, the numbers of colony forming units of bacteria (or numbers of Acanthamoeba trophozoites measured using a hemocytometer) from fimbrolide-coated and uncoated lenses were examined. A Guinea Pig model of lens wear was used to assess the safety of lenses worn on a continuous basis for 1 month. In a separate study, 10 subjects wore fimbrolide-coated lenses for 24 h. The responses of the Guinea Pigs and human volunteers to the lenses were assessed by slit lamp examination. The fimbrolides-coated lenses reduced the adhesion of all bacterial strains tested, with reductions occurring of between 67 and 92%. For Acanthamoeba a reduction of 70% was seen. There were no significant differences in ocular responses to fimbrolide-coated lenses compared with controls in either the 1 month animal model or overnight human trial. Fimbrolide-coated lenses show promise as an antibacterial and anti-acanthamoebal coating on contact lenses and appear to be safe when worn on the eye in an animal model.

Influence of wear and overwear on surface properties of etafilcon A contact lenses and adhesion of Pseudomonas aeruginosa

NARCIS (Netherlands)

Bruinsma, Gerda M; Rustema-Abbing, Minie; de Vries, Joop; Stegenga, Boudewijn; van der Mei, Henny C.; van der Linden, Matthijs L; Hooymans, Johanna MM; Busscher, Henk J.

2002-01-01

PURPOSE. To determine changes in physicochemical surface properties of contact tenses (CLs) during daily wear and effects of lens wear on adhesion of a Pseudomonas aeruginosa strain from a patient with CL-related keratitis. METHODS. Ten new CL wearers used ionic, etafilcon A lenses with 58% water on

Medindo o poder refrativo de lentes de contato gelatinosas personalizadas Measuring the refractive power of customized soft contact lenses

Directory of Open Access Journals (Sweden)

Luis Alberto Vieira de Carvalho

2007-02-01

tecnologia é importante para o desenvolvimento de novos métodos para correção de aberrações de pacientes que normalmente não podem passar por cirurgia refrativa e ao mesmo tempo estão insatisfeitos com os óculos de grau convencionais. Entre estes pacientes, podemos citar aqueles portadores de ceratocone ou que tenham sido submetidos ao transplante de córnea.PURPOSE: Soft contact lenses with spherical base curves have been used for many years. The computation of the refractive powers of these lenses is easy, requiring only that one uses the lens maker equation for thick lenses. Nevertheless, for customized contact lenses, there is yet no reliable method for measuring the higher order optical aberrations. In this study we have developed in the Center for Visual Sciences of the University of Rochester an optical apparatus that allows for precise measurement of low and high order aberrations of customized soft contact lenses. METHODS: An optical apparatus was mounted on a conventional optical bench. This apparatus consists of a wet cell where the contact lenses are placed, a series of relay lenses, mirrors, beam splitters, and a Hartmann-Shack sensor. Bausch & Lomb manufactured the lenses used in this study. RESULTS: The root mean square error (RMSE of the instrument was 0.04 microns. Given that the RMSE of the customized lens is between 4 and 6 microns, i.e., the precision of the instrument is approximately 1%. This precision is more than sufficient for the type of measurements necessary for manufacturing customized contact lenses. CONCLUSION: The instrument developed is extremely precise for measuring high order aberrations - up to the 10th order Zernike polynomials, that is, up to the 66th term. This technology is important for the development of new methods of optical corrections for patients that usually do not adapt to normal sphere-cylinder spectacles or that cannot undergo refractive surgery, such as those which have keratoconus, for example.

RISK FACTORS FOR CONTACT LENS COMPLICATIONS

Directory of Open Access Journals (Sweden)

Mirna Štabuc Šilih

2016-04-01

Full Text Available Contact lenses are freely available without professional examination and fitting, as well as without adequate introduction and instructions on handling, disinfection and storage. Contact lenses may have physiological, metabolic and anatomic effect on the eyes, which is manifested both on the eyelids, lacrimal film, conjunctiva and in all layers of the cornea - the epithelium, stroma and the endothelium. We can see these complications too often at our everyday work. The purpose of this paper is to draw attention to the potential complications due to inappropriate use of contact lenses.Contact lenses are otherwise a safe and effective method of correcting visual acuity; they are also useful for therapeutic purposes. Complications related to contact lenses wear could be largely avoided with an appropriate professional approach and the compliance of contact lens wearers. It is important to discuss with patients their medical history, their desires and expectations, their working and living environment; followed by professional examination of patients and appropriate fitting of contact lenses. Patients should receive detailed oral and written instructions and be subscribed to regular checks. But unfortunately, all this is not enough, if patients do not comply every day with given instructions.

Equivalences between refractive index and equilibrium water content of conventional and silicone hydrogel soft contact lenses from automated and manual refractometry.

Science.gov (United States)

González-Méijome, José M; López-Alemany, Antonio; Lira, Madalena; Almeida, José B; Oliveira, M Elisabete C D Real; Parafita, Manuel A

2007-01-01

The purpose of the present study was to develop mathematical relationships that allow obtaining equilibrium water content and refractive index of conventional and silicone hydrogel soft contact lenses from refractive index measures obtained with automated refractometry or equilibrium water content measures derived from manual refractometry, respectively. Twelve HEMA-based hydrogels of different hydration and four siloxane-based polymers were assayed. A manual refractometer and a digital refractometer were used. Polynomial models obtained from the sucrose curves of equilibrium water content against refractive index and vice-versa were used either considering the whole range of sucrose concentrations (16-100% equilibrium water content) or a range confined to the equilibrium water content of current soft contact lenses (approximately 20-80% equilibrium water content). Values of equilibrium water content measured with the Atago N-2E and those derived from the refractive index measurement with CLR 12-70 by the applications of sucrose-based models displayed a strong linear correlation (r2 = 0.978). The same correlations were obtained when the models are applied to obtain refractive index values from the Atago N-2E and compared with those (values) given by the CLR 12-70 (r2 = 0.978). No significantly different results are obtained between models derived from the whole range of the sucrose solution or the model limited to the normal range of soft contact lens hydration. Present results will have implications for future experimental and clinical research regarding normal hydration and dehydration experiments with hydrogel polymers, and particularly in the field of contact lenses. 2006 Wiley Periodicals, Inc.

Colored Contact Lens Dangers

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... Hazard: The Hidden Dangers of Buying Decorative Contact Lenses Without a Prescription Leer en Español: Peligros asociados ... truth." Real People, Real Problems with Colored Contact Lenses Julian: Teenager Blinded In One Eye By Non- ...

Colored Contact Lens Dangers

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Full Text Available ... like a suction cup." Halloween is a popular time for people to use colored contact lenses to ... wear costume contact lenses for Halloween or any time of year, follow these guidelines: Get an eye ...

Colored Contact Lens Dangers

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Full Text Available ... contact lenses , from the U.S. Food and Drug Administration (FDA). Are the colored lenses you are considering ... Follow The Academy Professionals: Education Guidelines News Multimedia Public & Patients: Contact Us About the Academy Jobs at ...

Colored Contact Lens Dangers

Medline Plus

Full Text Available ... Hazard: The Hidden Dangers of Buying Decorative Contact Lenses Without a Prescription Leer en Español: Peligros asociados ... truth." Real People, Real Problems with Colored Contact Lenses Julian: Teenager Blinded In One Eye By Non- ...

Microbial contamination of contact lenses, lens care solutions, and their accessories: a literature review.

Science.gov (United States)

Szczotka-Flynn, Loretta B; Pearlman, Eric; Ghannoum, Mahmoud

2010-03-01

A contact lens (CL) can act as a vector for microorganisms to adhere to and transfer to the ocular surface. Commensal microorganisms that uneventfully cohabitate on lid margins and conjunctivae and potential pathogens that are found transiently on the ocular surface can inoculate CLs in vivo. In the presence of reduced tissue resistance, these resident microorganisms or transient pathogens can invade and colonize the cornea or conjunctiva to produce inflammation or infection. The literature was reviewed and used to summarize the findings over the last 30 years on the identification, enumeration, and classification of microorganisms adherent to CLs and their accessories during the course of normal wear and to hypothesize the role that these microorganisms play in CL infection and inflammation. Lens handling greatly increases the incidence of lens contamination, and the ocular surface has a tremendous ability to destroy organisms. However, even when removed aseptically from the eye, more than half of lenses are found to harbor microorganisms, almost exclusively bacteria. Coagulase-negative Staphylococci are most commonly cultured from worn lenses; however, approximately 10% of lenses harbor Gram-negative and highly pathogenic species, even in asymptomatic subjects. In storage cases, the incidence of positive microbial bioburden is also typically greater than 50%. All types of care solutions can become contaminated, including up to 30% of preserved products. The process of CL-related microbial keratitis and inflammation is thought to be preceded by the presence or transfer or both of microorganisms from the lens to the ocular surface. Thus, this detailed understanding of lens-related bioburden is important in the understanding of factors associated with infectious and inflammatory complications. Promising mechanisms to prevent bacterial colonization on lenses and lens cases are forthcoming, which may decrease the incidence of microbially driven CL complications.

Measurement of the refractive index of soft contact lenses during wear.

Science.gov (United States)

Varikooty, Jalaiah; Keir, Nancy; Woods, Craig A; Fonn, Desmond

2010-01-01

To determine whether the refractive index (RI) of a soft contact lens can be evaluated using refractometry while the lens remains on the eye and to compare this with more traditional ex vivo RI measurements. A slitlamp apparatus was modified to incorporate a customized Atago hand refractometer. With a double-masked study design, nine adapted symptomatic soft contact lens wearers wore a contact lens in each eye (lotrafilcon B and etafilcon A) in a randomized order. In vivo RI was determined from the relative Brix scale measurements immediately after lens insertion and after 1 and 10 hr of lens wear. Ex vivo refractometry was performed after 10 hr of lens wear for comparison. Means +/- standard errors of the means are reported. In vivo RI values at baseline were 1.422 +/- 0.0004 (lotrafilcon B) and 1.405 +/- 0.0021 (etafilcon A); after 1 hr of lens wear, values were 1.423 +/- 0.0006 and 1.408 +/- 0.0007, respectively; and after 10 hr of lens wear, values were 1.424 +/- 0.0004 and 1.411 +/- 0.0010, respectively. Ex vivo RI values at the end of the 10 hr wearing period were 1.424 +/- 0.0003 (lotrafilcon B) and 1.412 +/- 0.0017 (etafilcon A). The change in in vivo RI across the day was statistically significant for the etafilcon A lens (repeated-measures analysis of variance, P0.05). This novel adaptation of refractometry was able to measure the RI of soft contact lenses during wear (without lens removal). End of day RI measurements using in vivo and ex vivo refractometry were comparable with each other. Future work is required to determine whether this in vivo method can improve our understanding of the relationships between soft contact lens RI, hydration, on-eye lens performance, and symptomology.

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.

Evaluation of safety and efficacy of a new multipurpose disinfecting solution on silicone hydrogel contact lenses.

Science.gov (United States)

Pinto-Fraga, José; Blázquez Arauzo, Francisco; Urbano Rodríguez, Rubén; González-García, María J

2015-01-01

To evaluate the safety and efficacy of a new multipurpose disinfecting solution (MPDS) with a formulation that includes aloe vera on its composition. This is a prospective, randomized, double-masked clinical trial with a crossover design that included seven examinations. Two different MPDSs, Avizor Alvera® (study solution) and All Clean Soft® (control solution), each were used for 1 month. Comfilcon A silicone hydrogel contact lenses were used during the trial. The main outcome variables were corneal staining and deposits on the surfaces of the contact lenses. Other parameters including ocular surface response, contact lens wettability, user satisfaction, and adverse events, were analyzed according to the International Organization for Standardization (ISO) 11980:2010 guidance for clinical investigation. Twenty subjects (10 women, 10 men) (mean age, 27.7±5.6 years; range, 20-41) were included. No differences between both MPDSs were found in the percentage of subjects with corneal staining >0 at day 30 (study: 35%, control: 50%; p=0.46); neither in the percentage of subjects with deposits on the surface of the contact lens >0 at day 30 (study: 26.32%, control: 52.63%; p=0.18). The study MPDS received higher rates in comfort (study: 8.14±1.09, control: 7.94±0.92; p=0.56) and satisfaction at day 30 (study: 8.63±0.91, control: 8.29±0.80; p=0.19), however the scores were not significantly different with the control MPDS. The clinical trial showed that the study MPDS is safe, efficient, and has acceptable physiologic tolerance, according to the ISO 11980:2010 guidance for clinical investigation. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

The effect of hydrogel and silicone hydrogel contact lenses on the measurement of intraocular pressure with rebound tonometry.

Science.gov (United States)

Zeri, Fabrizio; Calcatelli, Paolo; Donini, Bernardo; Lupelli, Luigi; Zarrilli, Luciana; Swann, Peter G

2011-12-01

To assess the accuracy of intraocular pressure (IOP) measurements using rebound tonometry over disposable hydrogel (etafilcon A) and silicone hydrogel (senofilcon A) contact lenses (CLs) of different powers. The experimental group comprised 36 subjects (19 male, 17 female). IOP measurements were undertaken on the subject's right eyes in random order using a rebound tonometer (ICare). The CLs had powers of +2.00D, -2.00D and -6.00D. Six measurements were taken over each contact lens and also before and after the CLs had been worn. A good correlation was found between IOP measurements with and without CLs (all r≥0.80; pContact Lens Association. Published by Elsevier Ltd. All rights reserved.

Inner layer-embedded contact lenses for pH-triggered controlled ocular drug delivery.

Science.gov (United States)

Zhu, Qiang; Liu, Chang; Sun, Zheng; Zhang, Xiaofei; Liang, Ning; Mao, Shirui

2018-07-01

Contact lenses (CLs) are ideally suited for controlled ocular drug delivery, but are limited by short release duration, poor storage stability and low drug loading. In this study, we present a novel inner layer-embedded contact lens capable of pH-triggered extended ocular drug delivery with good storage stability. Blend film of ethyl cellulose and Eudragit S100 was used as the inner layer, while pHEMA hydrogel was used as outer layer to fabricate inner layer-embedded contact lens. Using diclofenac sodium(DS) as a drug model, influence of polymer ratio in the blend film, EC viscosity, drug/polymer ratio, inner layer thickness and outlayer thickness of pHEMA hydrogel on drug release behavior was studied and optimized for daily use. The pH-triggered drug eluting pattern enables the inner layer-embedded contact lens being stored in phosphate buffer solution pH 6.8 with ignorable drug loss and negligible changes in drug release pattern. In vivo pharmacokinetic study in rabbits showed sustained drug release for over 24 h in tear fluid, indicating significant improvement in drug corneal residence time. A level A IVIVC was established between in vitro drug release and in vivo drug concentration in tear fluid. In conclusion, this inner layer embedded contact lens design could be used as a platform for extended ocular drug delivery with translational potential for both anterior and posterior ocular diseases therapy. Copyright © 2018 Elsevier B.V. All rights reserved.

Evaluation of Protamine as a Disinfectant for Contact Lenses.

Science.gov (United States)

Bandara, Mahesh K; Masoudi, Simin; Zhu, Hua; Bandara, Rani; Willcox, Mark D P

2016-11-01

To investigate the ability of protamine, alone or in combination with other antimicrobial agents, to kill bacteria and fungi associated with contact lens-related keratitis. The International Organization for Standardization 14729:2001 procedure was used to test the antimicrobial activity of solutions of protamine (23-228 μM) with and without polyhexamethylene biguanide (PHMB) and ethylenediamine tetra-acetic acid (EDTA). The recommended ISO panel of microbes along with six clinical isolates was tested. The effect of increasing sodium chloride concentration on the antimicrobial activity was also assessed. The cytotoxicity of the final protamine/EDTA/PHMB solution was measured using ISO 10993-5 standard assays. Protamine gave a dose-dependent antimicrobial effect, with the highest effect for most strains being at 228 μM (≥6 log reductions of viable bacteria and ≥1 log reduction of viable fungi). Addition of EDTA and PHMB increased the antimicrobial effect for all strains except Pseudomonas aeruginosa ATCC6538, which had optimum activity (≥6 log inhibition) even in protamine alone. The optimum antimicrobial activity of all microbes was achieved in 0.2% sodium chloride, but even in 0.8% sodium chloride, the activity met or exceeded the ISO standard (>3 log reductions for bacteria and >1 log reduction for fungi). None of the formulations was cytotoxic to mammalian cells. This study highlights the potential for protamine to be used for the development of effective multipurpose disinfection solutions. Further investigations such as stability, compatibility with contact lenses, and in vivo toxicity are warranted.

Plasma polymer-coated contact lenses for the culture and transfer of corneal epithelial cells in the treatment of limbal stem cell deficiency.

Science.gov (United States)

Brown, Karl David; Low, Suet; Mariappan, Indumathi; Abberton, Keren Maree; Short, Robert; Zhang, Hong; Maddileti, Savitri; Sangwan, Virender; Steele, David; Daniell, Mark

2014-02-01

Extensive damage to the limbal region of the cornea leads to a severe form of corneal blindness termed as limbal stem cell deficiency (LSCD). Whereas most cases of corneal opacity can be treated with full thickness corneal transplants, LSCD requires stem cell transplantation for successful ocular surface reconstruction. Current treatments for LSCD using limbal stem cell transplantation involve the use of murine NIH 3T3 cells and human amniotic membranes as culture substrates, which pose the threat of transmission of animal-derived pathogens and donor tissue-derived cryptic infections. In this study, we aimed to produce surface modified therapeutic contact lenses for the culture and delivery of corneal epithelial cells for the treatment of LSCD. This approach avoids the possibility of suture-related complications and is completely synthetic. We used plasma polymerization to deposit acid functional groups onto the lenses at various concentrations. Each surface was tested for its suitability to promote corneal epithelial cell adhesion, proliferation, retention of stem cells, and differentiation and found that acid-based chemistries promoted better cell adhesion and proliferation. We also found that the lenses coated with a higher percentage of acid functional groups resulted in a higher number of cells transferred onto the corneal wound bed in rabbit models of LSCD. Immunohistochemistry of the recipient cornea confirmed the presence of autologous, transplanted 5-bromo-2'-deoxyuridine (BrdU)-labeled cells. Hematoxylin staining has also revealed the presence of a stratified epithelium at 26 days post-transplantation. This study provides the first evidence for in vivo transfer and survival of cells transplanted from a contact lens to the wounded corneal surface. It also proposes the possibility of using plasma polymer-coated contact lenses with high acid functional groups as substrates for the culture and transfer of limbal cells in the treatment of LSCD.

Sistemas atuais de cuidados e manutenção de lentes de contato Current care and maintenance systems for contact lenses

Directory of Open Access Journals (Sweden)

César Lipener

2008-12-01

Full Text Available A correta manutenção das lentes de contato é fundamental para se obter sucesso e manter a continuidade de seu uso. É grande o número de pacientes que abandonam o uso de suas lentes por problemas que poderiam ser solucionados com tratamentos relativamente simples ou com uma orientação mais adequada. O mau uso das lentes, associado à má adaptação, contaminação, doenças oculares prévias e fatores ambientais, podem aumentar o número de infecções corneanas através da proliferação de microorganismos. O presente artigo visa apresentar as atualizações em relação aos cuidados e manutenção com as lentes de contato.The proper maintenance of contact lenses is crucial for their success and to maintain the continuity of their use. Many patients abandon the use of their lenses due to problems that could be solved with relatively simple treatments. The misuse of lenses, coupled with poor adjustment, contamination, eye disease and environmental factors may increase the number of corneal infections through the proliferation of microorganisms. This article aims to provide contact lens care and maintenance updates.

Colored Contact Lens Dangers

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Full Text Available ... eye-care professional. Retailers that sell contacts without a prescription are breaking the law, and may be fined $11,000 per violation. "Many of the lenses found online or in beauty salons, novelty shops or in pop-up ... contact lenses from a retailer that does not ask for a prescription. ...

Contact Lens Care

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... Consumers Consumer Information by Audience For Women Contact Lens Care Share Tweet Linkedin Pin it More sharing ... www.fda.gov/medwatch Learn More about Contact Lens Care Other Tips on Contact Lenses Decorative Contact ...

Solutions for care of silicone hydrogel lenses.

Science.gov (United States)

Willcox, Mark D P

2013-01-01

During wear of contact lenses on a daily wear basis, it is necessary to disinfect the lens overnight before reinserting the lens the next day. The ability of the solutions used for this to disinfect lenses and lens cases is important for safe lens wear. The literature on the disinfecting ability of multipurpose disinfecting solutions (MPDS) commonly used with silicone hydrogel lenses reported during the period 2000 to 2012 is reviewed, as this is the period of time during which these lenses have been commercially available. Particular emphasis is placed on the ability of disinfecting solutions to control colonization of lens cases by microbes and changes in composition and use of the solutions. In addition, the literature is reviewed on ways of minimizing lens case microbial contamination. Maintaining the hygiene of contact lenses and lens cases is important in minimizing various forms of corneal infiltrative events that occur during lens wear. Although lens case contamination is not associated with different lenses, it is determined by use of different MPDS. MPDS that allow more frequent or heavy contamination of cases by Gram-negative bacteria are associated with a higher incidence of corneal infiltrative events. MPDS are now available that contain dual disinfectants. Wiping lens cases with tissues or using lens cases that incorporate silver are associated with reductions in contamination in clinical trials. Similarly, using MPDS to rub and rinse lenses before disinfection may reduce levels of microbes on lenses. The MPDS also contain surfactants that help reduce deposition and denaturation of proteins on lenses. Improvements in MPDS formulations and hygiene practices may help to reduce the incidence of adverse events that are seen during use with silicone hydrogel lenses.

Acoustic lenses

International Nuclear Information System (INIS)

Kittmer, C.A.

1983-03-01

Acoustic lenses focus ultrasound to produce pencil-like beams with reduced near fields. When fitted to conventional (flat-faced) transducers, such lenses greatly improve the ability to detect and size defects. This paper describes a program developed to design acoustic lenses for use in immersion or contact inspection, using normal or angle beam mode with flat or curved targets. Lens surfaces are circular in geometry to facilitate machining. For normal beam inspection of flat plate, spherical or cylindrical lenses are used. For angle beam or curved surface inspections, a compound lens is required to correct for the extra induced aberration. Such a lens is aspherical with one radius of curvature in the plane of incidence, and a different radius of curvature in the plane perpendicular to the incident plane. The resultant beam profile (i.e., location of the acoustic focus, beam diameter, 6 dB working range) depends on the degree of focusing and the transducer used. The operating frequency and bandwidth can be affected by the instrumentation used. Theoretical and measured beam profiles are in good agreement. Various applications, from zone focusing used for defect sizing in thick plate, to line focusing for pipe weld inspection, are discussed

Bacterial transmission from lens storage cases to contact lenses-Effects of lens care solutions and silver impregnation of cases.

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Vermeltfoort, Pit B J; Hooymans, Johanna M M; Busscher, Henk J; van der Mei, Henny C

2008-10-01

The killing efficacies of multipurpose lens care solutions on planktonic and biofilm bacteria grown in polypropylene contact lens storage cases with and without silver impregnation and effects on bacterial transmission from storage cases to silicone hydrogel contact lenses were investigated. For transmission studies, biofilms of Staphylococcus aureus 835 or Pseudomonas aeruginosa no. 3 were grown on lens storage cases and incubated with a contact lens in different multipurpose lens care solutions (Opti-Free(R)Express(R), ReNu(R) MultiPlus(R), and SoloCare Aquatrade mark) or 0.9% NaCl. In addition, planktonic bacteria were directly suspended in multipurpose solutions and their killing efficacies were determined. The numbers of transmitted live and dead bacteria on the lenses were measured using a combination of plate counting and fluorescence microscopy. The highest killing efficacies were shown by Opti-Free(R) Express(R) for planktonic as well as for biofilm bacteria. Silver impregnation of lens cases in combination with the prescribed solution increased the killing efficacy for P. aeruginosa in biofilms, whereas effects for S. aureus were minor. Lowest numbers of live and dead bacteria were transmitted to a lens in Opti-Free(R) Express(R) multipurpose solution, with no significant differences between lens types and no effects of silver impregnation. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008. (c) 2008 Wiley Periodicals, Inc.

Optical performance of multifocal soft contact lenses via a single-pass method.

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Bakaraju, Ravi C; Ehrmann, Klaus; Falk, Darrin; Ho, Arthur; Papas, Eric

2012-08-01

A physical model eye capable of carrying soft contact lenses (CLs) was used as a platform to evaluate optical performance of several commercial multifocals (MFCLs) with high- and low-add powers and a single-vision control. Optical performance was evaluated at three pupil sizes, six target vergences, and five CL-correcting positions using a spatially filtered monochromatic (632.8 nm) light source. The various target vergences were achieved by using negative trial lenses. A photosensor in the retinal plane recorded the image point-spread that enabled the computation of visual Strehl ratios. The centration of CLs was monitored by an additional integrated en face camera. Hydration of the correcting lens was maintained using a humidity chamber and repeated instillations of rewetting saline drops. All the MFCLs reduced performance for distance but considerably improved performance along the range of distance to near target vergences, relative to the single-vision CL. Performance was dependent on add power, design, pupil, and centration of the correcting CLs. Proclear (D) design produced good performance for intermediate vision, whereas Proclear (N) design performed well at near vision (p 4 mm in diameter. Acuvue Oasys bifocal produced performance comparable with single-vision CL for most vergences. Direct measurement of single-pass images at the retinal plane of a physical model eye used in conjunction with various MFCLs is demonstrated. This method may have utility in evaluating the relative effectiveness of commercial and prototype designs.

Diffusion of Antimicrobials Across Silicone Hydrogel Contact Lenses.

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Zambelli, Alison M; Brothers, Kimberly M; Hunt, Kristin M; Romanowski, Eric G; Nau, Amy C; Dhaliwal, Deepinder K; Shanks, Robert M Q

2015-09-01

To measure the diffusion of topical preparations of moxifloxacin, amphotericin B (AmB), and polyhexamethylene biguanide (PHMB) through silicone hydrogel (SH) contact lenses (CLs) in vitro. Using an in vitro model, the diffusion of three antimicrobials through SH CLs was measured. Diffused compounds were measured using a spectrophotometer at set time points over a period of 4 hr. The amount of each diffused antimicrobial was determined by comparing the experimental value with a standard curve. A biological assay was performed to validate the CL diffusion assay by testing antimicrobial activity of diffused material against lawns of susceptible bacteria (Staphylococcus epidermidis) and yeast (Saccharomyces cerevisiae). Experiments were repeated at least two times with a total of at least four independent replicates. Our data show detectable moxifloxacin and PHMB diffusion through SH CLs at 30 min, whereas AmB diffusion remained below the limit of detection within the 4-hr experimental period. In the biological assay, diffused moxifloxacin demonstrated microbial killing starting at 20 min on bacterial lawns, whereas PHMB and AmB failed to demonstrate killing on microbial lawns over the course of the 60-min experiment. In vitro diffusion assays demonstrate limited penetration of certain anti-infective agents through SH CLs. Further studies regarding the clinical benefit of using these agents along with bandage CL for corneal pathologic condition are warranted.

Does correcting astigmatism with toric lenses improve driving performance?

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Cox, Daniel J; Banton, Thomas; Record, Steven; Grabman, Jesse H; Hawkins, Ronald J

2015-04-01

Driving is a vision-based activity of daily living that impacts safety. Because visual disruption can compromise driving safety, contact lens wearers with astigmatism may pose a driving safety risk if they experience residual blur from spherical lenses that do not correct their astigmatism or if they experience blur from toric lenses that rotate excessively. Given that toric lens stabilization systems are continually improving, this preliminary study tested the hypothesis that astigmats wearing toric contact lenses, compared with spherical lenses, would exhibit better overall driving performance and driving-specific visual abilities. A within-subject, single-blind, crossover, randomized design was used to evaluate driving performance in 11 young adults with astigmatism (-0.75 to -1.75 diopters cylinder). Each participant drove a highly immersive, virtual reality driving simulator (210 degrees field of view) with (1) no correction, (2) spherical contact lens correction (ACUVUE MOIST), and (3) toric contact lens correction (ACUVUE MOIST for Astigmatism). Tactical driving skills such as steering, speed management, and braking, as well as operational driving abilities such as visual acuity, contrast sensitivity, and foot and arm reaction time, were quantified. There was a main effect for type of correction on driving performance (p = 0.05). Correction with toric lenses resulted in significantly safer tactical driving performance than no correction (p driving safety from no correction (p = 0.118). Operational tests differentiated corrected from uncorrected performance for both spherical (p = 0.008) and toric (p = 0.011) lenses, but they were not sensitive enough to differentiate toric from spherical lens conditions. Given previous research showing that deficits in these tactical skills are predictive of future real-world collisions, these preliminary data suggest that correcting low to moderate astigmatism with toric lenses may be important to driving safety. Their

Comparison of quality of life between myopic patients with spectacles and contact lenses, and patients who have undergone refractive surgery

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Nastaran Shams

2015-03-01

Conclusion: Quality of life for people with myopia who had the refractive surgery was better than people with myopia who wore spectacles or contact lenses. Although quality of life in people with myopia who had the refractive surgery was less than emmetropia, it seems that refractive surgery improves quality of life of myopic patients.

Ocular discomfort responses after short periods of contact lens wear.

Science.gov (United States)

Papas, Eric; Tilia, Daniel; McNally, John; de la Jara, Percy Lazon

2015-06-01

To investigate if contact lens-related discomfort is a function of the time of day at which lenses are worn. This was a randomized, crossover, open-label clinical trial where subjective responses, with and without contact lenses, were assessed every 2 hours during five stages (A to E). Each stage began at the time when subjects would normally have inserted their contact lenses (T0). During stage A, no lenses were worn, whereas in stage B, lenses were worn continuously for 12 hours. In stages C to E, lenses were worn for only 4 hours. Contact lenses were inserted at T0 for stage C, but for stages D and E, lenses were not inserted until T0 + 4 and T0 + 8 hours, respectively. Mixed linear models were used for statistical analysis. In the absence of contact lenses, ocular comfort and dryness remained reasonably constant throughout the observation period. Ocular comfort and dryness decreased during 12 hours of continuous lens wear and became significantly worse from the 8-hour time onward compared with insertion (p 0.05) to the first 4 hours of continuous contact lens wear. Comparing the scores of each of these stages with the no-lens response at the corresponding time showed no significant differences for comfort (p > 0.23) or dryness (p > 0.37). Short periods of wear can be experienced at any time of day without significant change in ocular discomfort and dryness. This suggests that subjective responses at the end of the day are determined by the length of time lenses are in contact with the eye, rather than the time of day at which lenses are worn.

Producing optical (contact) lenses by a novel low cost process

Science.gov (United States)

Skipper, Richard S.; Spencer, Ian D.

2005-09-01

The rapid and impressive growth of China has been achieved on the back of highly labour intensive industries, often in manufacturing, and at the cost of companies and jobs in Europe and America. Approaches that worked well in the 1990's to reduce production costs in the developed countries are no longer effective when confronted with the low labour costs of China and India. We have looked at contact lenses as a product that has become highly available to consumers here but as an industry that has reduced costs by moving to low labour cost countries. The question to be answered was, "Do we have the skill to still make the product in the UK, and can we make it cheap enough to export to China?" if we do not, then contact lens manufacture will move to China sooner or later. The challenge to enter the markets of the BRIC (Brazil, Russia, India and China) countries is extremely exciting as here is the new money, high growth and here is a product that sells to those with disposable incomes. To succeed we knew we had to be radical in our approach; the radical step was very simple: to devise a process in which each step added value to the customer and not cost to the product. The presentation examines the processes used by the major producers and how, by applying good manufacturing practice sound scientific principles to them, the opportunity to design a new low cost patented process was identified.

Comparative evaluation of Comfilcon A and Senofilcon A bandage contact lenses after transepithelial photorefractive keratectomy.

Science.gov (United States)

Mukherjee, Achyut; Ioannides, Antonis; Aslanides, Ioannis

2015-01-01

To evaluate and compare Comfilcon A and Senofilcon A silicone hydrogel contact lenses used as a therapeutic bandage following transepithelial excimer laser photorefractive keratectomy (PRK). Patients undergoing transepithelial PRK for myopia were prospectively recruited. Included patients had a Comfilcon A silicone hydrogel lens inserted in one eye, with a Senofilcon A lens in the contralateral eye. Postoperative assessment of subjective pain, epithelial healing and visual recovery was at day 1, 3 and 7. Contact lens factors including centration, movement and deposits were assessed. 48 eyes of 24 patients were included in the study. Mean age was 31 years (SD 11) and mean refractive error -4.5 D (SD 1.8). Mean pain score at day 1 was significantly higher in the Comfilcon group at 4.6 (SD 2.7) vs. 1.5 (SD2.5) in the Senofilcon group (P<0.005). Mean time to healing was 3.17 days (SD 0.37) in the Comfilcon group, and 3.21 days (SD 0.4) in the Senofilcon group, with no difference in defect size. There was a pronounced central raphe in 1 eye in the Comfilcon group vs. 5 eyes in the Senofilcon group (P=0.19). Significantly more eyes demonstrated no lens movement in the Senofilcon group (18 vs. 4, P=0.0001). The variation in material characteristics and lens geometry of different silicone hydrogel lenses affects their clinical characteristics in therapeutic roles. Other factors than oxygen permeability may affect pain and epithelial healing, with superior pain relief from the less permeable Senofilcon lens in this study. Copyright © 2013 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Colored Contact Lens Dangers

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Full Text Available ... contact lenses , from the U.S. Food and Drug Administration (FDA). Are the colored lenses you are considering buying approved by ... 23, 2018 Solar Eclipse Inflicts Damage in the Shape of ...

Bacterial adhesion to conventional hydrogel and new silicone-hydrogel contact lens materials.

Science.gov (United States)

Kodjikian, Laurent; Casoli-Bergeron, Emmanuelle; Malet, Florence; Janin-Manificat, Hélène; Freney, Jean; Burillon, Carole; Colin, Joseph; Steghens, Jean-Paul

2008-02-01

As bacterial adhesion to contact lenses may contribute to the pathogenesis of keratitis, the aim of our study was to investigate in vitro adhesion of clinically relevant bacteria to conventional hydrogel (standard HEMA) and silicone-hydrogel contact lenses using a bioluminescent ATP assay. Four types of unworn contact lenses (Etafilcon A, Galyfilcon A, Balafilcon A, Lotrafilcon B) were incubated with Staphylococcus epidermidis (two different strains) and Pseudomonas aeruginosa suspended in phosphate buffered saline (PBS). Lenses were placed with the posterior surface facing up and were incubated in the bacterial suspension for 4 hours at 37 degrees C. Bacterial binding was then measured and studied by bioluminescent ATP assay. Six replicate experiments were performed for each lens and strain. Adhesion of all species of bacteria to standard HEMA contact lenses (Etafilcon A) was found to be significantly lower than that of three types of silicone-hydrogel contact lenses, whereas Lotrafilcon B material showed the highest level of bacterial binding. Differences between species in the overall level of adhesion to the different types of contact lenses were observed. Adhesion of P. aeruginosa was typically at least 20 times greater than that observed with both S. epidermidis strains. Conventional hydrogel contact lenses exhibit significantly lower bacterial adhesion in vitro than silicone-hydrogel ones. This could be due to the greater hydrophobicity but also to the higher oxygen transmissibility of silicone-hydrogel lenses.

Gram negative bacteria and contact lens induced acute red eye

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Sankaridurg Padmaja

1996-01-01

Full Text Available Two patients using hydrogel contact lenses on a daily wear schedule slept overnight with the lenses and woke up with a Contact Lens Induced Acute Red Eye (CLARE. The contact lenses recovered aseptically at the time of the event grew significant colonies of Pseudomonas aeruginosa and Aeromonas hydrophila in patient A and Pseudomonas aeruginosa and Serratia liquefaciens from patient B. Similar organisams from the contact lenses were recovered from the lens case and lens care solutions of patient B. In both the patients the condition resolved on discontinuation of lens wear. Patient compliance as a requirement for successful contact lens wear is highlighted with the illustration of these cases.

Immunoglobulin Concentration in Tears of Contact Lens Wearers

Science.gov (United States)

Maurya, Rajendra P.; Bhushan, Prashant; Singh, Virendra P.; Singh, Mahendra K.; Kumar, Prakash; Bhatia, Ravindra P.S.; Singh, Usha

2014-01-01

Purpose: To evaluate changes in the concentration of tear immunoglobulins in contact lens wearers. Methods: A total of 45 cases including 23 contact lens wearers (43 eyes) and 22 age and sex matched healthy controls having no ocular pathology were studied for immunoglobulins (IgA, IgG, IgM) in their tears by single radial immunodiffusion method. Results: Most of the cases used soft (56.6%) and semi-soft gas permeable (30.4%) contact lenses. Tear IgM was detected in only 17.4% and tear IgG in 43.6% of contact lens wearers, while in controls IgG was detected in 9.1% but none of the controls had IgM. There was a significant rise in total tear IgA (13.17 ± 4.44 mg/dl) in contact lens wearer as compared to controls (8.93 ± 3.79 mg/dl). Rise of tear IgA was more in symptomatic patients (15.38 ± 5.28 mg/dl) and in those wearing hard (19.73 ± 5.43 mg/dl) and semi-soft contact lenses (13.31 ± 5.43 mg/dl). A significant increase in tear IgA was noticed in subjects wearing lenses for >3 years (15.69 ± 5.39 mg/dl). About 43.4% of lens wearers were symptomatic and 80% of their lenses showed deposits and/or haziness. All cases with IgM in tear were symptomatic. Conclusion: The relation of immunoglobulin concentration with increasing duration of wear and material of contact lens shows that tear immunoglobulin rise accrues due to mechanical stimulation, hence contact lenses should not be used for a long period and lenses of hard nature should be discouraged. The maintenance, cleaning and deproteinization of the lenses are of high importance to avoid immunostimulation. PMID:25667732

Avaliação da qualidade óptica de lentes de contato gelatinosas na correção de miopia Evaluation of optical performance of soft contact lenses in myopic correction

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Marcelo Weslley Dalcoll

2008-12-01

ções de acuidade visual logMAR de baixo contraste, sensibilidade ao contraste, índice de Strehl, MTF e das aberrações de alta ordem.PURPOSE: To evaluate the optical performance of eyes fitted with two different soft contact lenses: Acuvue® 2 (Vistacon J&J Vision Care Inc., USA and World Vision Disposable Asférica Wave Front® (World Vision Ophthalmic, Brazil. METHODS: An interventional prospective clinical trial studied a sample of 40 myopic patients (-0.75D to -4.50D, with or without astigmatism up to -0.75D. Each patient had one eye randomized to visual performance evaluation including high and low contrast visual acuities, wavefront analysis and contrast sensitivity. RESULTS: The Nidek OPD Scan detected a residual refraction (hypercorrection for both contact lenses. High contrast visual acuity was significantly higher for World Vision soft contact lenses. Low contrast visual acuity was similar for both soft contact lenses. Contrast sensitivity improved significantly at 1.5; 3; 6 e 18 spatial frequencies for both soft contact lenses, but no difference was found between them. Regarding wavefront analysis, no difference was found between both soft contact lenses. There were not significantly differences in the Strehl indices and MTF for both soft contact lenses. CONCLUSION: World Vision Disposable Asférica Wave Front® soft contact lenses had a better performance regarding high contrast visual acuity. However, low contrast visual acuity, wavefront analysis and contrast sensitivity were similar for both soft contact lenses.

Colored Contact Lens Dangers

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Full Text Available ... had not been properly fitted by an eye care professional, the lenses stuck to my eye like ... lenses do not require the same level of care or consideration as a standard contact lens because ...

Immunoglobulin Concentration in Tears of Contact Lens Wearers

Directory of Open Access Journals (Sweden)

Rajendra P Maurya

2014-01-01

Conclusion: The relation of immunoglobulin concentration with increasing duration of wear and material of contact lens shows that tear immunoglobulin rise accrues due to mechanical stimulation, hence contact lenses should not be used for a long period and lenses of hard nature should be discouraged. The maintenance, cleaning and deproteinization of the lenses are of high importance to avoid immunostimulation.

Colored Contact Lens Dangers

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Full Text Available ... use of colored contact lenses , from the U.S. Food and Drug Administration (FDA). Are the colored lenses ... 2018 By Dan T. Gudgel Do you know what the difference is between ophthalmologists and optometrists? A ...

Colored Contact Lens Dangers

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Full Text Available ... colored contact lenses , from the U.S. Food and Drug Administration (FDA). Are the colored lenses you are ... this month in the New England Journal of Medicine. Unfortunately, this kind of injury is all too ...

Colored Contact Lens Dangers

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Full Text Available ... use of colored contact lenses , from the U.S. Food and Drug Administration (FDA). Are the colored lenses you are considering buying approved by the ... Service For Advertisers For Media Ophthalmology Job Center © American ...

Coagulase-negative staphylococci isolated from ocular wound infections after laser refractive surgery: attachment to and accumulation on soft contact lenses.

Science.gov (United States)

Faghri, Jamshid; Razavi, Mohamad Reza

2009-03-01

Disposable soft contact lenses that are commonly used after laser refractive surgery are known to be colonized by bacteria and play a key role in Bacterial Keraitis (BK) pathogenesis. Coagulase-negative staphylococci (CoNS) have been found to be the most common pathogen involved in this postoperative infection. In this study a rapid and a simple assay was developed for studying attachment and accumulation of CoNS on soft contact lenses in vitro using [3H] thymidine. Thirty-five isolates of CoNS were obtained from 27 laser refractive surgery patients. Twenty-five of these thirty-five CoNS were isolated in multiple cultures. Ten CoNS were isolated in cultures from patients who underwent reoperation. The assay was optimized using a biofilm-producing strain, S. epidermidis RP62A, which was subcultured overnight at 37 degrees C on blood agar medium. Quantitative determination of biofilm production was tested. Presence of the genes icaADB and icaD was determined in all isolates. All isolates were biochemically analyzed using the Phene Plate (PhP) system modified for typing of CoNS. The CoNS isolates were further characterized to species level using ID32Staph.Mann-Whitney rank sum test and chi-square test were used to identify statistical differences in adherence, index, antibiotic susceptibility patterns, and biofilm production or presence of the ica operon between clinically significant isolates and non-postoperative BK isolates. No differences in attachment and accumulation were found between isolates causing BK after laser refractive surgery and contaminant isolates. In addition, there were no differences in the distribution of the ica operon between the two groups, as determined by polymerase chain reaction. Nevertheless, the ability to produce biofilm was found to be present significantly more frequently among BK isolates than among non-postoperative BK isolates. This study shows that the method using radioactive thymidine to analyze adherence of CoNS to soft

High Dk piggyback contact lens system for contact lens-intolerant keratoconus patients.

Science.gov (United States)

Sengor, Tomris; Kurna, Sevda Aydin; Aki, Suat; Ozkurt, Yelda

2011-01-01

The aim of the study was to examine the clinical success of high Dk (oxygen permeability) piggyback contact lens (PBCL) systems for the correction of contact lens intolerant keratoconus patients. Sixteen patients (29 eyes) who were not able to wear gas-permeable rigid lenses were included in this study. Hyper Dk silicone hydrogel (oxygen transmissibility or Dk/t = 150 units) and fluorosilicone methacrylate copolymer (Dk/t = 100 units) lenses were chosen as the PBCL systems. The clinical examinations included visual acuity and corneal observation by biomicroscopy, keratometer reading, and fluorescein staining before and after fitting the PBCL system. INDICATIONS FOR USING PBCL SYSTEM WERE: lens stabilization and comfort, improving comfort, and adding protection to the cone. Visual acuities increased significantly in all of the patients compared with spectacles (P = 0). Improvement in visual acuity compared with rigid lenses alone was recorded in 89.7% of eyes and no alteration of the visual acuity was observed in 10.3% of the eyes. Wearing time of PBCL systems for most of the patients was limited time (mean 6 months, range 3-12 months); thereafter they tolerated rigid lenses alone except for 2 patients. The PBCL system is a safe and effective method to provide centering and corneal protection against mechanical trauma by the rigid lenses for keratoconus patients and may increase contact lens tolerance.

Colored Contact Lens Dangers

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Full Text Available ... use of colored contact lenses , from the U.S. Food and Drug Administration (FDA). Are the colored lenses ... away without suffering an eye injury. However, the natural protective mechanisms of the eye – such as the ...

Efficacy of detergent and water versus bleach for disinfection of direct contact ophthalmic lenses.

Science.gov (United States)

Abbey, Ashkan M; Gregori, Ninel Z; Surapaneni, Krishna; Miller, Darlene

2014-06-01

Although manufacturers recommend cleaning ophthalmic lenses with detergent and water and then with a specific disinfectant, disinfectants are rarely used in ophthalmic practices. The aim of this pilot study was to evaluate the efficacy of detergent and water versus that of bleach, a recommended disinfectant, to eliminate common ocular bacteria and viruses from ophthalmic lenses. Three bacterial strains (Staphylococcus epidermidis, Corynebacterium straitum, and methicillin-resistant Staphylococcus aureus and 2 viral strains (adenovirus and herpes simplex virus [HSV] type-1) were individually inoculated onto 20 gonioscopy and laser lenses. The lenses were washed with detergent and water and then disinfected with 10% bleach. All the lenses were cultured after inoculation, after washing with detergent and water, and after disinfecting with the bleach. Bacterial cultures in thioglycollate broth were observed for 3 weeks, and viral cultures were observed for 2 weeks. The presence of viruses was also detected by multiplex polymerase chain reaction (PCR). All 20 lenses inoculated with S. epidermidis, C. straitum, adenovirus, and HSV-1 showed growth after inoculation but no growth after washing with detergent/water and after disinfecting with the bleach. All lenses showed positive HSV and adenovirus PCR results after inoculation and negative PCR results after washing with detergent/water and after disinfecting with bleach. All methicillin-resistant S. aureus-contaminated lenses showed growth after inoculation and no growth after washing with detergent and water. However, 1 lens showed positive growth after disinfecting with bleach. Cleaning with detergent and water seemed to effectively eliminate bacteria and viruses from the surface of contaminated ophthalmic lenses. Further studies are warranted to design practical disinfection protocols that minimize lens damage.

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

Colored Contact Lens Dangers

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Full Text Available ... One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume ... Costume Contact Lenses Can Ruin Vision Eye Makeup Safety In fact, it is illegal to sell colored ...

Daily disposable contact lens prescribing around the world.

Science.gov (United States)

Efron, Nathan; Morgan, Philip B; Helland, Magne; Itoi, Motozumi; Jones, Deborah; Nichols, Jason J; van der Worp, Eef; Woods, Craig A

2010-10-01

Daily disposable contact lenses were introduced into the market 16 years ago. Data that we have gathered from annual contact lens fitting surveys conducted in Australia, Canada, Japan, The Netherlands, Norway, the UK and the USA between 2000 and 2008 indicates an overall increase in daily disposable lens fitting during this period. Daily disposable lenses are especially popular in Japan, Norway and the UK. There is a trend for these lenses to be fitted on a part-time basis. Males are over-represented in daily disposable lens fitting-a trend that is especially evident in Canada. Daily disposable lens wearers are about two years younger than wearers of reusable lenses in Japan and The Netherlands. The convenience and health benefits of daily disposable lenses are expected to fuel continued growth in this sector. Copyright (c) 2010 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Contact lenses as drug controlled release systems: a narrative review

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Helena Prior Filipe

2016-06-01

Full Text Available ABSTRACT Topically applied therapy is the most common way to treat ocular diseases, however given the anatomical and physiological constraints of the eye, frequent dosing is required with possible repercussions in terms of patient compliance. Beyond refractive error correction, contact lenses (CLs have, in the last few decades emerged as a potential ophthalmic drug controlled release system (DCRS. Extensive research is underway to understand how to best modify CLs to increase residence time and bioavailability of drugs within therapeutic levels on the ocular surface.These devices may simultaneously correct ametropia and have a role in managing ophthalmic disorders that can hinder CL wear such as dry eye, glaucoma, ocular allergy and cornea infection and injury. In this narrative review the authors explain how the ocular surface structures determine drug diffusion in the eye and summarize the strategies to enhance drug residence time and bioavailability. They synthesize findings and clinical applications of drug soaked CLs as DCRS combined with delivery diffusion barriers, incorporation of functional monomers, ion related controlled release, molecular imprinting, nanoparticles and layering. The authors draw conclusions about the impact of these novel ophthalmic agents delivery systems in improving drug transport in the target tissue and patient compliance, in reducing systemic absorption and undesired side effects, and discuss future perspectives.

Keep Contacts Clean (A Minute of Health with CDC)

Centers for Disease Control (CDC) Podcasts

For millions of Americans, contact lenses are a popular alternative to glasses. If not properly worn and cared for, they can put wearers at risk for eye infections. This podcast discusses proper care for contact lenses.

Keep Contacts Clean (A Cup of Health with CDC)

Centers for Disease Control (CDC) Podcasts

Contact lenses can be a comfortable and convenient alternative to traditional eye glasses, but without proper care, they can cause severe eye problems. In this podcast, Sarah Collier discusses the importance of proper maintenance of contact lenses.

Colored Contact Lens Dangers

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Full Text Available ... the United States. All contact lenses are medical devices that require a prescription and proper fitting by an eye-care professional. Retailers that sell contacts without a ...

Health beliefs affect the correct replacement of daily disposable contact lenses: Predicting compliance with the Health Belief Model and the Theory of Planned Behaviour.

Science.gov (United States)

Livi, Stefano; Zeri, Fabrizio; Baroni, Rossella

2017-02-01

To assess the compliance of Daily Disposable Contact Lenses (DDCLs) wearers with replacing lenses at a manufacturer-recommended replacement frequency. To evaluate the ability of two different Health Behavioural Theories (HBT), The Health Belief Model (HBM) and The Theory of Planned Behaviour (TPB), in predicting compliance. A multi-centre survey was conducted using a questionnaire completed anonymously by contact lens wearers during the purchase of DDCLs. Three hundred and fifty-four questionnaires were returned. The survey comprised 58.5% females and 41.5% males (mean age 34±12years). Twenty-three percent of respondents were non-compliant with manufacturer-recommended replacement frequency (re-using DDCLs at least once). The main reason for re-using DDCLs was "to save money" (35%). Predictions of compliance behaviour (past behaviour or future intentions) on the basis of the two HBT was investigated through logistic regression analysis: both TPB factors (subjective norms and perceived behavioural control) were significant (pbehaviour and future intentions) and perceived benefit (only for past behaviour) as significant factors (pbehavioural control of daily replacement (behavioural control) are of paramount importance in improving compliance. With reference to the HBM, it is important to warn DDCLs wearers of the severity of a contact-lens-related eye infection, and to underline the possibility of its prevention. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Controlled delivery of pirfenidone through vitamin E-loaded contact lens ameliorates corneal inflammation.

Science.gov (United States)

Dixon, Phillip; Ghosh, Tanushri; Mondal, Kalyani; Konar, Aditya; Chauhan, Anuj; Hazra, Sarbani

2018-06-01

Chemical injury by alkali burn is a major cause of corneal blindness in the clinical setting. Current management advocates multiple therapies aimed to prevent inflammation, initiate quick re-epithelialization, arrest the fibrosis, and avoid dry eye and pain by using bandage contact lenses. We hypothesized sustained delivery of the anti-inflammatory, antifibrotic drug pirfenidone through vitamin E-loaded contact lenses as a logical single approach to counter the pathology involved. Vitamin E particles were created in situ in commercial silicon hydrogel contact lenses by soaking the lenses in a vitamin E-ethanol solution. The vitamin E-laden lenses were then placed into pirfenidone-saline solution to load the drug into the lens. The contact lenses were evaluated by both in vitro and in vivo means. For in vitro, lenses were placed into 3 mL of saline solution. The concentration of pirfenidone released was measured by UV-vis spectrophotometry. The contact lenses were implanted in rabbit eyes following the alkali burn; the drug availability in the aqueous humor was evaluated by HPLC at various time points 10 min, 30 min, 2 h, and 3 h; and gene expression of inflammatory cytokines IL-1β, TNF-α, and TGF-β1 was evaluated in the cornea at the end of the study period. In another group of rabbits inflicted with alkali injury, the corneas were graded after 7 days of contact lens implantation with and without pirfenidone. A mathematical model was developed for delivery of the drug to the cornea and aqueous humor after a contact lens is inserted in the eye. The model was validated with experimental data and used to determine the bioavailability both for contact lenses and eye drops. In vitro release of unmodified commercial contact lenses saw a release time of approximately 20 min, with a partition coefficient of 2.68 ± 0.06. The release of pirfenidone from 20% vitamin E-loaded lenses saw a release time of approximately 80 min, with a partition coefficient of 4

Applanation tonometry in silicone hydrogel contact lens wearers.

Science.gov (United States)

Allen, R J; Dev Borman, A; Saleh, G M

2007-12-01

Previous studies have investigated intraocular pressure (IOP) measurements through conventional soft (hydrogel) therapeutic contact lenses, and have found that an accurate IOP can be recorded in normal eyes, and in eyes with abnormal anterior segments. The IOP measurement through soft contact lenses may be affected by the water content and centre thickness of the lens. Silicone hydrogel contact lenses are now being used as therapeutic contact lenses due to their high oxygen permeability. The purpose of this study is to investigate if IOP can be accurately measured in a subject wearing a silicone hydrogel contact lens. In a cohort study, the IOP was measured with a Goldmann applanation tonometer without a contact lens and then repeated with a hydrogel contact lens in situ. The IOP of 20 eyes of 10 volunteers with no ocular pathology was measured. The mean difference (+/-S.D.) found between IOP measurement with (mean 15.55+/-1.70 mmHg) and without (mean 16.05+/-1.90 mmHg) contact lens was found to be -0.5+/-0.89 mmHg. Statistical analysis was performed which revealed a correlation coefficient of 0.89. No significant statistical difference was found between the two groups with paired t-test (p=0.19). Accurate measurement of IOP by applanation tonometry can be achieved through a silicone hydrogel contact lens.

Efficacy of Detergent and Water Versus Bleach for the Disinfection of Direct Contact Ophthalmic Lenses

Science.gov (United States)

Abbey, Ashkan M.; Gregori, Ninel Z.; Surapaneni, Krishna; Miller, Darlene

2014-01-01

Purpose While manufacturers recommend cleaning ophthalmic lenses with detergent and water and then a specific disinfectant, disinfectants are rarely used in ophthalmic practices. The aim of this pilot study was to evaluate the efficacy of detergent and water versus bleach, a recommended disinfectant, to eliminate common ocular bacteria and viruses from ophthalmic lenses. Methods Three bacterial strains (Staphylococcus epidermidis, Corynebacterium straitum, and methicillin-resistant Staphylococcus aureus (MRSA) and two viral strains (adenovirus and herpes simplex virus (HSV) type-1) were individually inoculated to 20 gonioscopy and laser lenses. Lenses were washed with detergent and water and then disinfected with 10% bleach. All lenses were cultured after inoculation, after detergent and water, and after the bleach. Bacterial cultures in thioglycollate broth were observed for 3 weeks and viral cultures for 2 weeks. The presence of viruses was also detected by multiplex polymerase chain reaction (PCR). Results All 20 lenses inoculated with Staphylococcus epidermidis, Corynebacterium straitum, adenovirus, and HSV-1 showed growth after inoculation, but no growth after detergent/water and after the bleach. All lenses showed positive HSV and adenovirus PCR after inoculation and negative PCR after detergent/water and after bleach. All MRSA contaminated lenses showed growth after inoculation and no growth after detergent and water. However, one lens showed positive growth after bleach. Conclusions Cleaning with detergent and water appeared to effectively eliminate bacteria and viruses from the surface of contaminated ophthalmic lenses. Further studies are warranted to design practical disinfection protocols that minimize lens damage. PMID:24747806

Corneal thinning associated with recurrent microbial keratitis resulting from 7-day extended wear of low Dk hydrogel contact lenses: a case report.

Science.gov (United States)

Cardona, Genís; Saona-Santos, Carlos Luís

2010-02-01

Corneal thinning and an increased risk of corneal perforation, resulting from recurrent episodes of microbial keratitis, required a 38-year-old Caucasian female to undergo bilateral corneal grafting. Although strongly advised otherwise, the patient had been a long time user of low oxygen permeability hydrogel contact lenses in a flexible wear regime, with frequent overnight use. Microbial keratitis is a potentially severe contact lens related complication which, if not properly treated, may lead to permanent visual loss. The introduction of silicone-hydrogel materials and daily replacement modalities has not resulted in a significant decrease in the incidence of microbial keratitis, thus suggesting that the condition is mainly dependent on patient hygiene and wearing habits. Non-compliance, which is endemic in contact lens wear, may be combated by increasing patient awareness of the potential risk factors of contact lens misuse. This is accomplished through constant, rigorous information provided by contact lens practitioners.

Contact Lens Safety (A Cup of Health with CDC)

Centers for Disease Control (CDC) Podcasts

Contact lenses are a convenient and effective alternative to traditional eye glasses, but improper care and use can result in severe damage to the eyes. In this podcast, Dr. Jennifer Cope discusses the importance of proper care and use of contact lenses.

Evaluation of refractive correction for standard automated perimetry in eyes wearing multifocal contact lenses.

Science.gov (United States)

Hirasawa, Kazunori; Ito, Hikaru; Ohori, Yukari; Takano, Yui; Shoji, Nobuyuki

2017-01-01

To evaluate the refractive correction for standard automated perimetry (SAP) in eyes with refractive multifocal contact lenses (CL) in healthy young participants. Twenty-nine eyes of 29 participants were included. Accommodation was paralyzed in all participants with 1% cyclopentolate hydrochloride. SAP was performed using the Humphrey SITA-standard 24-2 and 10-2 protocol under three refractive conditions: monofocal CL corrected for near distance (baseline); multifocal CL corrected for distance (mCL-D); and mCL-D corrected for near vision using a spectacle lens (mCL-N). Primary outcome measures were the foveal threshold, mean deviation (MD), and pattern standard deviation (PSD). The foveal threshold of mCL-N with both the 24-2 and 10-2 protocols significantly decreased by 2.2-2.5 dB ( P correction without additional near correction is to be recommended.

Intraocular pressure readings obtained through soft contact lenses using four types of tonometer.

Science.gov (United States)

Takenaka, Joji; Kunihara, Eriko; Rimayanti, Ulfah; Tanaka, Junko; Kaneko, Makoto; Kiuchi, Yoshiaki

2015-01-01

To compare the reliability and accuracy of intraocular pressure (IOP) measured while wearing soft contact lenses (SCLs) using a non-contact tonometer (NCT), Goldmann applanation tonometer (GAT), iCare rebound tonometer (RBT) and the Tono-Pen XL. Twenty-six healthy subjects were examined. The IOP was measured using NCT, GAT, RBT, and the Tono-Pen XL, while the subjects wore SCLs -5.00 D, -0.50 D and +5.00 D. Bland-Altman plots and a regression analysis were used to compare the IOPs obtained with those instruments and the IOPs of the naked eyes measured using GAT (the standard IOPs in this study). The IOPs obtained by the Tono-Pen XL while the subjects were wearing -5.00 D, -0.50 D, and +5.00 D SCLs were significantly higher than those of the naked eyes obtained using GAT. RBT showed that the IOPs were similar to the GAT standard IOPs under all conditions. The IOPs measured with NCT and GAT while the subjects were wearing -5.00 D and -0.50 D SCLs were similar to the GAT standard IOPs. The IOPs obtained with RBT and NCT while the subjects were wearing -5.00 D and -0.50 D SCLs exhibited a good correlation with the standard IOPs. The NCT and RBT are best when measuring IOP through hydrogel SCLs.

Adhesion of Pseudomonas aeruginosa to orthokeratology and alignment lenses.

Science.gov (United States)

Choo, Jennifer D; Holden, Brien A; Papas, Eric B; Willcox, Mark D P

2009-02-01

To determine whether contact lenses designed for orthokeratology (OK) are colonized by greater numbers of bacteria compared with standard (alignment fitted) design rigid gas permeable lenses before and after lens wear. Eighteen 1-year-old cats were randomly fitted with an OK lens in one eye and an alignment fitted (AF) lens in the other eye. Both lenses were made in the same diameter and central thickness and of the same material. Two separate wearing periods of 2 weeks and 6 weeks were used. After each wearing period, lenses were soaked in Pseudomonas aeruginosa (6294 or 6206) for 10 min. The lenses were then reinserted onto their respective corneas for a wearing period of 16 hours after which lenses were collected and remaining adhered bacteria quantified. Unworn control lenses were also soaked and bacteria enumerated for comparison. There were no significant differences in the number of bacteria adherent to unworn AF and OK lenses. Analysis of lenses after wear showed OK lenses retained significantly higher numbers of viable bacteria than AF lenses in all studies. OK lenses retain more bacteria than AF rigid gas permeable lenses after bacteria-loaded overnight lens wear. This may increase the risk for an infection in OK patients should suitable conditions be present. Specific education on the cleaning of OK lenses is essential.

Efeito do filtro de ultravioleta em lentes de contato hidrofílicas de alta hidratação Ultraviolet filter effect on hydrophilic high hydrated contact lenses

Directory of Open Access Journals (Sweden)

Arlindo José Freire Portes

2008-06-01

Full Text Available A exposição à radiação ultravioleta está relacionada ao aparecimento de patologias oculares como ceratites, cataratas, degenerações maculares ou pterígio. Esta radiação está dividida em 3 tipos de acordo com o seu comprimento de onda: Uv-A (320-400nm, Uv-B (290-320nm e Uv-C (100-290nm. A indústria óptica desenvolveu filtros de ultravioleta para lentes intra-oculares, lentes de contato e lentes de óculos. OBJETIVO: Avaliar a eficácia do filtro de ultravioleta em lentes de contato de alta hidratação. MÉTODOS: Seis grupos de lentes de contato de alta hidratação e de marcas diferentes, contendo 3 unidades novas e iguais foram estudadas, observando-se o percentual de transmissão da energia luminosa de 200 a 400 nm através de um espectofotômetro. RESULTADOS: Os 3 grupos que apresentavam filtro de ultravioleta causaram uma queda abrupta na transmissão da radiação ultravioleta de 400 nm até 340 nm, ocorrendo um aumento na transmissão entre 240 a 300 nm até um nível máximo de 45%. Abaixo de 240 nm e entre 300 e 340 nm, houve um completo bloqueio da transmissão da radiação ultravioleta. Os 3 grupos que não apresentavam filtros de ultravioleta causaram uma queda abrupta na transmissão da radiação ultravioleta abaixo de 240 nm, ocorrendo um bloqueio completo de transmissão abaixo de 220 nm. CONCLUSÃO: As lentes de contato sem filtro Uv testadas não bloquearam com eficácia a radiação Uv-A, B ou C, e as com filtro bloquearam quase totalmente a radiação Uv-B e parcialmente a radiação Uv-A e Uv-C.The exposure to ultraviolet radiation is associated with the beginning of ocular pathologies like keratites, cataract, age-related macular degeneration and pterygium. This radiation is divided in 3 bands according to the wave length: Uv-A (320-400, Uv-B (290-320, Uv-C (100-290. The optic industry developed ultraviolet filters to intraocular lenses, contact lenses and spectacle lenses. PURPOSE: The issue of this work is

Increased resistance of contact lens related bacterial biofilms to antimicrobial activity of soft contact lens care solutions

Science.gov (United States)

Szczotka-Flynn, Loretta B.; Imamura, Yoshifumi; Chandra, Jyotsna; Yu, Changping; Mukherjee, Pranab K.; Pearlman, Eric; Ghannoum, Mahmoud A.

2014-01-01

PURPOSE To determine if clinical and reference strains of Pseudomonas aeruginosa, Serratia marcescens, and Staphylococcus aureus form biofilms on silicone hydrogel contact lenses, and ascertain antimicrobial activities of contact lens care solutions. METHODS Clinical and American Type Culture Collection (ATCC) reference strains of Pseudomonas aeruginosa, Serratia marcescens, and Staphylococcus aureus were incubated with lotrafilcon A lenses under conditions that facilitate biofilm formation. Biofilms were quantified by quantitative culturing (colony forming units, CFUs), and gross morphology and architecture were evaluated using scanning electron microscopy (SEM) and confocal microscopy. Susceptibilities of the planktonic and biofilm growth phases of the bacteria to five common multipurpose contact lens care solutions and one hydrogen peroxide care solution were assessed. RESULTS P. aeruginosa, S. marcescens, and S. aureus reference and clinical strains formed biofilms on lotrafilcon A silicone hydrogel contact lenses, as dense networks of cells arranged in multiple layers with visible extracellular matrix. The biofilms were resistant to commonly used biguanide preserved multipurpose care solutions. P. aeruginosa and S. aureus biofilms were susceptible to a hydrogen peroxide and a polyquaternium preserved care solution, whereas S. marcescens biofilm was resistant to a polyquaternium preserved care solution but susceptible to hydrogen peroxide disinfection. In contrast, the planktonic forms were always susceptible. CONCLUSIONS P. aeruginosa, S. marcescens, and S. aureus form biofilms on lotrafilcon A contact lenses, which in contrast to planktonic cells, are resistant to the antimicrobial activity of several soft contact lens care products. PMID:19654521

Colored Contact Lens Dangers

Medline Plus

Full Text Available ... Cleveland. "This is far from the truth." Real People, Real Problems with Colored Contact Lenses Julian: Teenager ... about the members of the eye-care team . Consumer warning about the improper use of colored contact ...

Colored Contact Lens Dangers

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Full Text Available ... Costume Contacts May Contain Chemicals Harmful to Eyes Four Ways Over-the-Counter Costume Contact Lenses Can ... was in severe pain and on medication for four weeks, and couldn't see well enough to ...

Colored Contact Lens Dangers

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Full Text Available ... sell contacts without a prescription are breaking the law, and may be fined $11,000 per violation. " ... wear any kind of contact lens. In Butler's case, the lenses caused an infection and left her ...

Colored Contact Lens Dangers

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Full Text Available ... glow-in-the-dark lizard lenses, costume contacts can certainly add a spooky, eye-popping touch. But ... consideration as a standard contact lens because they can be purchased over-the-counter or on the ...

Colored Contact Lens Dangers

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Full Text Available ... MD, professor of ophthalmology at Case Western Reserve University in Cleveland. "This is far from the truth." ... use of colored contact lenses , from the U.S. Food and Drug Administration (FDA). Are the colored lenses you are considering buying approved by the ... Service For Advertisers For Media Ophthalmology Job Center © American ...

Intraocular pressure readings obtained through soft contact lenses using four types of tonometer

Directory of Open Access Journals (Sweden)

Takenaka J

2015-10-01

Full Text Available Joji Takenaka,1 Eriko Kunihara,1 Ulfah Rimayanti,2 Junko Tanaka,3 Makoto Kaneko,4 Yoshiaki Kiuchi1 1Department of Ophthalmology and Visual Science, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan; 2Faculty of Medicine and Health Sciences, UIN Alauddin Makassar, South Sulawesi, Indonesia; 3Department of Epidemiology, Infectious Disease Control and Prevention, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan; 4Graduate School of Engineering, Osaka University, Osaka, Japan Purpose: To compare the reliability and accuracy of intraocular pressure (IOP measured while wearing soft contact lenses (SCLs using a non-contact tonometer (NCT, Goldmann applanation tonometer (GAT, iCare rebound tonometer (RBT and the Tono-Pen XL.Methods: Twenty-six healthy subjects were examined. The IOP was measured using NCT, GAT, RBT, and the Tono-Pen XL, while the subjects wore SCLs -5.00 D, -0.50 D and +5.00 D. Bland–Altman plots and a regression analysis were used to compare the IOPs obtained with those instruments and the IOPs of the naked eyes measured using GAT (the standard IOPs in this study.Results: The IOPs obtained by the Tono-Pen XL while the subjects were wearing -5.00 D, -0.50 D, and +5.00 D SCLs were significantly higher than those of the naked eyes obtained using GAT. RBT showed that the IOPs were similar to the GAT standard IOPs under all conditions. The IOPs measured with NCT and GAT while the subjects were wearing -5.00 D and -0.50 D SCLs were similar to the GAT standard IOPs. The IOPs obtained with RBT and NCT while the subjects were wearing -5.00 D and -0.50 D SCLs exhibited a good correlation with the standard IOPs.Conclusion: The NCT and RBT are best when measuring IOP through hydrogel SCLs. Keywords: soft contact lens, intraocular pressure, rebound tonometer, non-contact tonometer

Colored Contact Lens Dangers

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Full Text Available ... prescription. Follow the contact lens care directions for cleaning, disinfecting, and wearing the lenses. Never share contact ... with Industry Medical Disclaimer Privacy Policy Terms of Service For Advertisers For Media Ophthalmology Job Center © American ...

Effect of multizone refractive multifocal contact lenses on standard automated perimetry.

Science.gov (United States)

Madrid-Costa, David; Ruiz-Alcocer, Javier; García-Lázaro, Santiago; Albarrán-Diego, César; Ferrer-Blasco, Teresa

2012-09-01

The aim of this study was to evaluate whether the creation of 2 foci (distance and near) provided by multizone refractive multifocal contact lenses (CLs) for presbyopia correction affects the measurements on Humphreys 24-2 Swedish interactive threshold algorithm (SITA) standard automated perimetry (SAP). In this crossover study, 30 subjects were fitted in random order with either a multifocal CL or a monofocal CL. After 1 month, a Humphrey 24-2 SITA standard strategy was performed. The visual field global indices (the mean deviation [MD] and pattern standard deviation [PSD]), reliability indices, test duration, and number of depressed points deviating at P0.5% on pattern deviation probability plots were determined and compared between multifocal and monofocal CLs. Thirty eyes of 30 subjects were included in this study. There were no statistically significant differences in reliability indices or test duration. There was a statistically significant reduction in the MD with the multifocal CL compared with monfocal CL (P=0.001). Differences were not found in PSD nor in the number of depressed points deviating at P0.5% in the pattern deviation probability maps studied. The results of this study suggest that the multizone refractive lens produces a generalized depression in threshold sensitivity as measured by the Humphreys 24-2 SITA SAP.

Keep Contacts Clean (A Minute of Health with CDC)

Centers for Disease Control (CDC) Podcasts

2015-09-03

For millions of Americans, contact lenses are a popular alternative to glasses. If not properly worn and cared for, they can put wearers at risk for eye infections. This podcast discusses proper care for contact lenses.  Created: 9/3/2015 by MMWR.   Date Released: 9/3/2015.

Fitting an MSD (mini scleral design) rigid contact lens in advanced keratoconus with INTACS.

Science.gov (United States)

Dalton, Kristine; Sorbara, Luigina

2011-12-01

Keratoconus is a bilateral degenerative disease characterized by a non-inflammatory, progressive central corneal ectasia (typically asymmetric) and decreased vision. In its early stages it may be managed with spectacles and soft contact lenses but more commonly it is managed with rigid contact lenses. In advanced stages, when contact lenses can no longer be fit, have become intolerable, or corneal damage is severe, a penetrating keratoplasty is commonly performed. Alternative surgical techniques, such as the use of intra-stromal corneal ring segments (INTACS) have been developed to try and improve the fit of rigid contact lenses in keratoconic patients and avoid penetrating keratoplasties. This case report follows through the fitting of rigid contact lenses in an advanced keratoconic cornea after an INTACS procedure and discusses clinical findings, treatment options, and the use of mini-scleral and scleral lens designs as they relate to the challenges encountered in managing such a patient. Mini-scleral and scleral lenses are relatively easy to fit, and can be of benefit to many patients, including advanced keratoconic patients, post-INTAC patients and post-penetrating keratoplasty patients. 2011 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

the level of contact lens practice in port harcourt, rivers state of ...

African Journals Online (AJOL)

LIVINGSTON

routine optometric examination- keratometer, slit lamp biomicroscope, retinoscope, trial case, and diagnostic contact lenses. For diagnostic contact lenses, the practitioner can confine himself to just a few lens types . A successful contact lens practice would involve astute practice management. Type of practice to be offered ...

Keep Contacts Clean (A Cup of Health with CDC)

Centers for Disease Control (CDC) Podcasts

2014-11-20

Contact lenses can be a comfortable and convenient alternative to traditional eye glasses, but without proper care, they can cause severe eye problems. In this podcast, Sarah Collier discusses the importance of proper maintenance of contact lenses.  Created: 11/20/2014 by MMWR.   Date Released: 11/20/2014.

Relative performance of soft contact lenses having lathe-cut posterior surfaces with and without additional polishing.

Science.gov (United States)

O'Brien, C; Charman, W N

2006-05-01

After a preliminary investigation of the effects of tool feed rate and spindle speed on the surface roughness of unhydrated, lathe-cut polymacon surfaces, a laboratory and clinical comparison was made between lenses with identical parameters except that the lathe-cut posterior surface was left unpolished in the "test" lenses and was polished in the "control" lenses. The lenses had moulded anterior surfaces. Laboratory comparisons included surface roughness, lens power and its uniformity across the surface. Double-blind clinical trials over 4-hour (27 subjects) and 1-month (10 subjects) periods, involved one eye of each subject wearing a "test" lens and the other, a "control" lens. No clinically significant differences were found between the results for the test and control lenses. It is concluded that today's lathing technology makes a final polishing stage unnecessary.

Contact Lens Safety (A Cup of Health with CDC)

Centers for Disease Control (CDC) Podcasts

2016-08-18

Contact lenses are a convenient and effective alternative to traditional eye glasses, but improper care and use can result in severe damage to the eyes. In this podcast, Dr. Jennifer Cope discusses the importance of proper care and use of contact lenses.  Created: 8/18/2016 by MMWR.   Date Released: 8/18/2016.

Pseudomonas aeruginosa Survival at Posterior Contact Lens Surfaces after Daily Wear

Science.gov (United States)

Wu, Yvonne T.; Zhu, Lucia S.; Tam, K. P. Connie; Evans, David J.; Fleiszig, Suzanne M. J.

2015-01-01

Purpose Pseudomonas aeruginosa keratitis is a sight-threatening complication of contact lens wear, yet mechanisms by which lenses predispose to infection remain unclear. Here, we tested the hypothesis that tear fluid at the posterior contact lens surface can lose antimicrobial activity over time during lens wear. Methods Daily disposable lenses were worn for 1, 2, 4, 6 or 8 h immediately after removal from their packaging, or after presoaking in sterile saline for 2 days to remove packaging solution. Unworn lenses were also tested, some coated in tears “aged” in vitro for 1 or 8 h. Lenses were placed anterior surface down into tryptic soy agar cradles containing gentamicin (100µg/ml) to kill bacteria already on the lens, and posterior surfaces inoculated with gentamicin-resistant P. aeruginosa for 3 h. Surviving bacteria were enumerated by viable counts of lens homogenates. Results Posterior surfaces of lenses worn by patients for 8 h supported more P. aeruginosa growth than lenses worn for only 1 h, if lenses were presoaked prior to wear (~ 2.4-fold, p = 0.01). This increase was offset if lenses were not presoaked to remove packaging solution (p = 0.04 at 2 h and 4 h). Irrespective of presoaking, lenses worn for 8 h showed more growth on their posterior surface than unworn lenses coated with tear fluid that was “aged” for 8 h vitro (~8.6-fold, presoaked, p = 0.003: ~ 5.4-fold from packaging solution, p = 0.004). Indeed, in vitro incubation did not impact tear antimicrobial activity. Conclusions This study shows that post lens tear fluid can lose antimicrobial activity over time during contact lens wear, supporting the idea that efficient tear exchange under a lens is critical for homeostasis. Additional studies are needed to determine applicability to other lens types, wearing modalities, and relevance to contact lens-related infections. PMID:25955639

The use of contact lens telescopic systems in low vision rehabilitation.

Science.gov (United States)

Vincent, Stephen J

2017-06-01

Refracting telescopes are afocal compound optical systems consisting of two lenses that produce an apparent magnification of the retinal image. They are routinely used in visual rehabilitation in the form of monocular or binocular hand held low vision aids, and head or spectacle-mounted devices to improve distance visual acuity, and with slight modifications, to enhance acuity for near and intermediate tasks. Since the advent of ground glass haptic lenses in the 1930's, contact lenses have been employed as a useful refracting element of telescopic systems; primarily as a mobile ocular lens (the eyepiece), that moves with the eye. Telescopes which incorporate a contact lens eyepiece significantly improve the weight, comesis, and field of view compared to traditional spectacle-mounted telescopes, in addition to potential related psycho-social benefits. This review summarises the underlying optics and use of contact lenses to provide telescopic magnification from the era of Descartes, to Dallos, and the present day. The limitations and clinical challenges associated with such devices are discussed, along with the potential future use of reflecting telescopes incorporated within scleral lenses and tactile contact lens systems in low vision rehabilitation. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Colored Contact Lens Dangers

Medline Plus

Full Text Available ... like a suction cup." Halloween is a popular time for people to use colored contact lenses to enhance their costumes. From ... MD, professor of ophthalmology at Case Western Reserve University in Cleveland. "This is far ... Use Facts About Colored Contacts and Halloween Safety Colored ...

Racial variations in interfacial behavior of lipids extracted from worn soft contact lenses

OpenAIRE

Svitova, TF; Lin, MC

2013-01-01

PURPOSE: To explore interfacial behaviors and effects of temperature and dilatation on dynamic properties of multilayered human tear lipids extracted from silicone hydrogel (SiH) lenses worn by asymptomatic Asian and white subjects. METHODS: Interfacial properties of lipids extracted from Focus NandD lenses worn by 14 subjects continuously for 1 month were studied. The lipids were deposited on an air bubble immersed in a model tear electrolyte (MTE) solution to form 100 ± 20-nm-thick films. S...

Slit lamps and lenses: a potential source of nosocomial infections?

Science.gov (United States)

Sobolewska, Bianka; Buhl, Michael; Liese, Jan; Ziemssen, Focke

2018-01-30

The aim of the study was to evaluate the bacterial contamination level of contact surfaces on slit lamps and the grip areas of lenses. Within unannounced audits, two regions of the slit lamps (headrest and joystick), indirect ophthalmoscopy devices, and ultrasound probes were obtained with rayon-tipped swab. Non-contact lenses used for indirect fundoscopy were pressed on RODAC (Replicate Organism Detection and Counting) plates. One hundred and eighty-one surfaces were sampled. The total number of colony-forming units was assessed and bacterial species were identified. Spa-typing and antimicrobial susceptibility testing were performed from Staphylococcus aureus isolates. Among the total bacterial isolates from ophthalmological equipment (lenses: 51 of 78, slit lamps: 43 of 88, ophthalmoscopy helmets: 3 of 8, ultrasound probes: 2 of 7), coagulase-negative staphylococci (CNS) was most frequently found, followed by Micrococcus spp. (lenses vs. slit lamps: P lenses (76%) was significantly higher than that of slit lamps (54%) (P lenses from residents vs. from consultants (78% vs. 35%, P = 0.01). A total of seven different spa-types of S. aureus were isolated. No correlation was found between S. aureus contamination of different ophthalmological equipments (Spearman's rank correlation coefficient, ρ = 0.04, P = 0.75). Methicillin-resistant S. aureus was not detected. Bacterial species of the normal skin flora were isolated from the ophthalmological equipment. The bacterial contamination of the portable devices was significantly higher than that of slit lamps. Therefore, proper hygiene of the mobile instruments should be monitored in order to prevent transmission of bacteria in residents and consultants.

Microbial contamination of contact lenses after scaling and root planing using ultrasonic scalers with and without protective eyewear: A clinical and microbiological study

OpenAIRE

Afzha, Rooh; Chatterjee, Anirban; Subbaiah, Shobha Krishna; Pradeep, Avani Rangaraju

2016-01-01

Background: Ultrasonic scaler is a preferential treatment modality among the clinicians. However, the aerosol/splatter generated is a concern for patients and practitioners. Therefore, the purpose of this study was to evaluate contamination of contact lenses of the dentist after scaling and root planing using ultrasonic scalers with and without protective eyewear. Materials and Methods: Thirty patients were randomly selected for scaling and root planing and divided into 2 groups of 15 each. G...

Lentes de contato filtrantes coloridas nas discromatopsias: relato de casos Absorptive and colored contact lenses in color-vision defects: case report

Directory of Open Access Journals (Sweden)

Luciene Chaves Fernandes

2003-06-01

Full Text Available As autoras propõem a utilização de lentes de contato filtrantes coloridas para melhora da discriminação de cores e do ofuscamento, em portadores de discromatopsia, na impossibilidade de montagem de filtros coloridos em óculos. Foram adaptadas lentes de contato filtrantes coloridas em dois portadores de discromatopsias, um com deutanopia e outro com acromatopsia. No primeiro, adaptou-se lente rígida filtrante, de polimetilmetacrilato (PMMA, vermelha, no olho não dominante, com o objetivo de melhorar a discriminação de cores. No segundo, colocou-se lente filtrante gelatinosa, de uso diário, de coloração marrom escuro com pupila âmbar, visando melhorar o ofuscamento. No primeiro caso, o paciente manteve inalterada a acuidade visual e também o contraste, porém demonstrou melhora na discriminação das cores ao teste de PV-16. No segundo caso, houve melhora subjetiva acentuada do ofuscamento tanto em ambiente interno, como externo. A acuidade visual e a visão de cores permaneceram sem alterações. Os achados sugerem a possibilidade de contarmos com as lentes de contato filtrantes coloridas como importante auxílio para a melhora na discriminação de cores e ofuscamento, nas discromatopsias.The authors propose the use of absorptive and colored contact lenses as an aid to color defects in making color judgments and reduce glare sensitivity in dichromatic subjects, when the use of filter in glasses is not possible. Absorptive and colored contact lenses were adapted in two dichromatic subjects, one deutanope and the other with achromatopsia. In the former, a hard absorptive, red-colored, polymethacrylate lens was adapted monocularly, in the non-dominant eye to help color judgments. In the latter, a soft absorptive, dark brown-colored lens with amber pupil was worn in both eyes to reduce glare sensitivity. Subject # 1 remained with the same visual acuity and contrast sensitivity and demonstrated a better color perception on the PV-16

Contact lens wearers' experiences while trekking in the Khumbu region/Nepal: a cross-sectional survey.

Science.gov (United States)

Bauer, Irmgard L

2015-01-01

Safe contact lens wear depends on a hygiene regime and lens-appropriate wear patterns which may be compromised during travel in remote and wilderness areas. The purpose of this study was to describe the experience of contact lens wearers while trekking at high-altitude in Nepal. For this descriptive study, trekkers with contact lenses were recruited in Lukla and invited to complete an online-questionnaire on trip preparation, contact lens use, care and experiences, and possible changes for future travel. Quantitative data were analysed using SurveyMonkey; content analysis applied to qualitative responses. The majority of the 158 participants (124; 78.48%) reported no problems with their lenses (daily disposables, soft lenses, extended-wear lenses, hard/rigid lenses) during their stay although dry air, dust, wind, cold temperatures, and difficult hygiene maintenance were challenging. Freezing lenses and freezing solutions were additional challenges. Thirty-four (21.52%) experienced a variety of problems. Improvements were requested from manufacturers. Lodges should provide better access to clean water, mirrors and lighting. Almost 60% of participants had not sought any pre-travel health advice. Remote and wilderness areas provide a challenge for appropriate contact lens wear and care. The decision between the potential risk of infection due to touching lenses (daily disposables, soft/hard lenses) and the potential risk of corneal erosion (extended-wear lenses) needs to be made in pre-travel consultations. Travel health professionals and travel agencies should remind CL-wearing trekkers to carefully assess their wear and care routine to accommodate potentially challenging conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

An evaluation of 1-day disposable contact lens wear in a population of allergy sufferers.

Science.gov (United States)

Hayes, Valérie Y; Schnider, Cristina M; Veys, Jane

2003-06-01

This was a multi-site, 128-subject, bilateral crossover study to evaluate subjective comfort and slit-lamp findings with 1-day disposable contact lenses in a population of allergy sufferers during periods when allergen levels were elevated. The study involved 1-month of single-use daily wear with a 1-day disposable test lens (1. DAY ACUVUE Brand Contact Lenses, Johnson & Johnson Vision Care) and 1-month of daily wear with subjects' habitual lenses replaced to their usual replacement schedule. Pollen and mould counts were obtained for each site 1 week prior to the study and twice weekly throughout the study period. Subjective comfort and slit-lamp findings were recorded at baseline and after 1-month's wear of each modality. Sixty-seven percent of subjects agreed that the 1-day disposable lenses provided improved comfort when compared to the lenses they wore prior to the study, compared with 18% agreeing that the new pair of habitual lenses provided improved comfort. The 1-day disposable lenses showed greater improvement in slit-lamp findings from baseline than new habitual lenses. The use of 1-day disposable lenses is an effective strategy for managing allergy-suffering contact lens wearers.

Colored Contact Lens Dangers

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Bacterial adhesion to unworn and worn silicone hydrogel lenses.

Science.gov (United States)

Vijay, Ajay Kumar; Zhu, Hua; Ozkan, Jerome; Wu, Duojia; Masoudi, Simin; Bandara, Rani; Borazjani, Roya N; Willcox, Mark D P

2012-08-01

The objective of this study was to determine the bacterial adhesion to various silicone hydrogel lens materials and to determine whether lens wear modulated adhesion. Bacterial adhesion (total and viable cells) of Staphylococcus aureus (31, 38, and ATCC 6538) and Pseudomonas aeruginosa (6294, 6206, and GSU-3) to 10 commercially available different unworn and worn silicone hydrogel lenses was measured. Results of adhesion were correlated to polymer and surface properties of contact lenses. S. aureus adhesion to unworn lenses ranged from 2.8 × 10 to 4.4 × 10 colony forming units per lens. The highest adhesion was to lotrafilcon A lenses, and the lowest adhesion was to asmofilcon A lenses. P. aeruginosa adhesion to unworn lenses ranged from 8.9 × 10 to 3.2 × 10 colony forming units per lens. The highest adhesion was to comfilcon A lenses, and the lowest adhesion was to asmofilcon A and balafilcon A lenses. Lens wear altered bacterial adhesion, but the effect was specific to lens and strain type. Adhesion of bacteria, regardless of genera/species or lens wear, was generally correlated with the hydrophobicity of the lens; the less hydrophobic the lens surface, the greater the adhesion. P. aeruginosa adhered in higher numbers to lenses in comparison with S. aureus strains, regardless of the lens type or lens wear. The effect of lens wear was specific to strain and lens. Hydrophobicity of the silicone hydrogel lens surface influenced the adhesion of bacterial cells.

The Risk of Contact Lens Wear and the Avoidance of Complications

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Farihah Tariq

2013-11-01

Full Text Available Contact lenses are lenses placed on the surface of the cornea to correct refractive errors such as myopia (short-sightedness, hypermetropia (far-sightedness and astigmatism. Lens-related complications are becoming a greater health concern as increasing number of individuals are using them as an alternative to spectacles. Contact lenses alter the natural ocular environment and reduce the efficacy of the innate defences. Although many complications are minor, microbial keratitis is potentially blinding and suspected cases should be rapidly diagnosed and referred to an ophthalmologist for treatment. Several risk factors have been identified with extended wear, poor hand hygiene, inadequate lens and lens-case care being the most significant. Promotion of good contact lens hygiene and practices are essential to reduce the adverse effects of contact lens wear.

Phospholipids and their degrading enzyme in the tears of soft contact lens wearers.

Science.gov (United States)

Yamada, Masakazu; Mochizuki, Hiroshi; Kawashima, Motoko; Hata, Seiichiro

2006-12-01

Low tear phospholipids levels are associated with tear film instability in soft contact lens wearers. We assayed levels of phospholipids and their degrading enzyme secretory phospholipase A2 (sPLA2) both in tears and deposited on contact lenses composed of 2 hydrophilic materials after 1 day of routine use. Polymacon (Medalist; FDA group 1, low water/nonionic) and Etafilcon A (One Day Acuvue; group 4, high water/ionic) contact lenses were worn for 12 hours by 16 experienced contact lens wearers. Phospholipids in tear fluids and deposited on contact lenses were estimated by phosphorus determination with ammonium molybdate through enzymatic digestion. Double-antibody sandwich ELISA was used to determine group IIa sPLA2 concentrations, and sPLA2 activity was assayed using 1,2-diheptanoyl thio-phosphatidylcholine as substrate. Phospholipids concentrations in tears with Polymacon and Etafilcon A were 186 +/- 39 and 162 +/- 33 microg/mL, respectively. The latter concentration was significantly lower than that observed in the same subjects when not wearing contact lenses (P = 0.0023). In tears, both group IIa sPLA2 concentrations and enzymatic activity remained unchanged, regardless of lens wearing. However, Etafilcon A (0.57 +/- 0.09 microg/lens) showed more group IIa sPLA2 deposition than Polymacon (0.01 +/- 0.01 microg/lens; P < 0.001). Furthermore, group IIa sPLA2 deposited on Etafilcon A but not on Polymacon lenses retained its enzymatic activity. Significant differences of group IIa sPLA2 deposition were found in the 2 lenses tested. Such deposition might induce phospholipid hydrolysis in tears and thereby promote tear film instability in hydrophilic contact lens wearers.

Colored Contact Lens Dangers

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Full Text Available ... MD, professor of ophthalmology at Case Western Reserve University in Cleveland. "This is far from the truth." Real People, Real Problems with Colored Contact Lenses Julian: Teenager Blinded In ...

The role of type III secretion system and lens material on adhesion of Pseudomonas aeruginosa to contact lenses.

Science.gov (United States)

Shen, Elizabeth P; Tsay, Ruey-Yug; Chia, Jean-San; Wu, Semon; Lee, Jing-Wen; Hu, Fung-Rong

2012-09-21

To determine the distribution of invasive and cytotoxic genotypes among ocular isolates of P. aeruginosa and investigate the influence of the type III secretion system (T3SS) on adhesion to conventional, cosmetic, and silicone hydrogel contact lenses (CL). Clinical isolates from 2001 to 2010 were analyzed by multiplex PCR for exoS, exoU, and exoT genes. Bacterial adhesion to etafilcon, nelfilcon (gray colored), balafilcon, and galyfilcon CL with or without artificial tear fluid (ATF) incubation were compared. Surface characteristics were determined with scanning electron microscopy (SEM). Among 87 total isolates, 64 strains were from microbial keratitis cases. CL-related microbial keratitis (CLMK) isolates were mostly of the cytotoxic genotype (expressing exoU) (P = 0.002). No significant differences were found in bacterial adhesion to all types of CL between the genotypes under T3SS-inducing conditions. A trend for least bacterial adhesion of galyfilcon compared to the other CL was noted for both genotypes. Needle complex pscC mutants adhered less to all materials than the wild type (P bacteria adhering on CL surfaces. CLMK isolates were mostly of cytotoxic genotype. Different genotypes did not significantly differ in its adhesion to various CL. T3SS and other adhesins are involved in bacteria-contact lens adhesion through complex interactions. Contact lens materials may also play an important role in the adherence of both genotypes of P. aeruginosa.

Desempenho visual de lentes de contato gelatinosas de diferentes tipos baseado na análise de frentes de onda Optical performance of different soft contact lenses based on wavefront analysis

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Roberta Fagnani Gatti

2008-12-01

valor médio de outras aberrações de alta ordem (que exclui coma de terceira ordem e aberração esférica de quarta ordem, caracterizada pelo componente "outros" no exame de aberrometria. As lentes Focus® Choice AB apresentaram melhor desempenho visual em relação a este componente. CONCLUSÕES: O uso de lentes de contato gelatinosas alteram o comportamento das aberrações de alta ordem, com tendência ao aumento no valor médio das aberrações de Zernike assimétricas. Tal tendência ao aumento não foi verificada para as aberrações simétricas. Não foram encontradas diferenças estatisticamente significantes ao compararmos o padrão de influência obtido com os seis tipos de lentes incluídos no estudo.PURPOSE: To evaluate the visual performance by wavefront analyses of six different kinds of soft contact lenses: Cooperflex® (Cooper Vision, Frequency® 55 Aspheric (Cooper Vision, World Vision FW® (World Vision, Pure Vision® (Bausch & Lomb, Focus® Monthly (Ciba Vision and Focus® Choice AB (Ciba Vision. METHODS: A prospective study was performed with 130 eyes of 71 myopic or hyperopic patients with astigmatism until 1.50 diopter and best corrected visual acuity 20/20 or better. The patients first underwent ophthalmic examination and then wavefront analyses without visual correction and wearing one of the different contact lenses included in the study. The patients were divided into six similar groups, each one tested with one of the six lenses included in the study. RESULTS: Changes at the values of high order aberrations were verified during the use of contact lenses. In 78 (60% of the 130 analyzed eyes an increase at the RMS (rooth mean square values during the use of contact lens was detected. All types of analyzed contact lenses showed an increase of "coma" aberrations due to contact lens use. Frequency® Aspheric and Cooperflex® had the best visual performance in relation to "coma". There was a decrease in the medium value of spherical aberrations

Sustained Ocular Delivery of Ciprofloxacin Using Nanospheres and Conventional Contact Lens Materials

Science.gov (United States)

Garhwal, Rahul; Shady, Sally F.; Ellis, Edward J.; Ellis, Jeanne Y.; Leahy, Charles D.; McCarthy, Stephen P.; Crawford, Kathryn S.

2012-01-01

Purpose. To formulate conventional contact lenses that incorporate nanosphere-encapsulated antibiotic and demonstrate that the lenses provide for sustained antibacterial activity. Methods. A copolymer composed of pullulan and polycaprolactone (PCL) was used to synthesize core-shell nanospheres that encapsulated ciprofloxacin. Bactericidal activity of the nanosphere-encapsulated ciprofloxacin (nanosphere/cipro) was tested by using liquid cultures of either Staphylococcus aureus or Pseudomonas aeruginosa. Nanosphere/cipro was then incorporated into HEMA-based contact lenses that were tested for growth inhibition of S. aureus or P. aeruginosa in liquid cultures inoculated daily with fresh bacteria. Lens designs included thin or thick lenses incorporating nanosphere/cipro and ciprofloxacin-HCl-soaked Acuvue lenses (Acuvue; Johnson & Johnson Vision Care, Inc., Jacksonville, FL). Results. Less than 2 μg/mL of nanosphere/cipro effectively inhibited the proliferation of cultures inoculated with 107 or 108 bacteria/mL of S. aureus and P. aeruginosa, respectively. HEMA-based contact lenses polymerized with nanosphere/cipro were transparent, effectively inhibited the proliferation of greater than 107/mL of bacteria added daily over 3 days of culture, and killed up to 5 × 109 total microbes in a single inoculation. A thicker lens design provided additional inhibition of bacterial growth for up to 96 hours. Conclusions. Core-shell nanospheres loaded with an antibiotic can be incorporated into a conventional, transparent contact lens and provide for sustained and effective bactericidal activity and thereby provide a new drug delivery platform for widespread use in treating ocular disorders. PMID:22266514

Fungal Keratitis Due to Beauveria bassiana in a Contact Lenses Wearer and Review of Published Reports.

Science.gov (United States)

Lara Oya, Ana; Medialdea Hurtado, María Eloisa; Rojo Martín, María Dolores; Aguilera Pérez, Antonia; Alastruey-Izquierdo, Ana; Miranda Casas, Consuelo; Rubio Prats, Marina; Medialdea Marcos, Santiago; Navarro Marí, José María

2016-10-01

Fungal keratitis is a severe ocular infection that primarily affects subjects engaged in outdoor activities. Risk factors include allergic conjunctivitis, previous eye surgery, previous treatment with wide-spectrum antimicrobial agents and corticosteroids and using contact lenses. Corneal infection is usually secondary to trauma involving organic material, which is often the only predisposing factor. Early diagnosis based on clinical examination and microbiological investigation (microscopy, cultures and molecular techniques) is crucial to selecting the appropriate antifungal therapy and prevent progression. We report the case of a patient with keratitis due to Beauveria bassiana, an opportunistic and entomopathogenic filamentous fungus that is used as a biological insecticide and which is a rare cause of corneal infection. We review previous cases reports of B. bassiana keratitis published and its main features to compare with our case, a female occasional agriculture worker who had not suffered any trauma involving organic material. The patient received topical and oral antifungal therapy and debridement surgery, with a satisfactory outcome.

Evaluation of refractive correction for standard automated perimetry in eyes wearing multifocal contact lenses

Directory of Open Access Journals (Sweden)

Kazunori Hirasawa

2017-10-01

Full Text Available AIM: To evaluate the refractive correction for standard automated perimetry (SAP in eyes with refractive multifocal contact lenses (CL in healthy young participants. METHODS: Twenty-nine eyes of 29 participants were included. Accommodation was paralyzed in all participants with 1% cyclopentolate hydrochloride. SAP was performed using the Humphrey SITA-standard 24-2 and 10-2 protocol under three refractive conditions: monofocal CL corrected for near distance (baseline; multifocal CL corrected for distance (mCL-D; and mCL-D corrected for near vision using a spectacle lens (mCL-N. Primary outcome measures were the foveal threshold, mean deviation (MD, and pattern standard deviation (PSD. RESULTS: The foveal threshold of mCL-N with both the 24-2 and 10-2 protocols significantly decreased by 2.2-2.5 dB CONCLUSION: Despite the induced mydriasis and the optical design of the multifocal lens used in this study, our results indicated that, when the dome-shaped visual field test is performed with eyes with large pupils and wearing refractive multifocal CLs, distance correction without additional near correction is to be recommended.

Acanthamoeba keratitis in Scotland: risk factors for contact lens wearers.

Science.gov (United States)

Seal, D V; Kirkness, C M; Bennett, H G; Peterson, M

1999-01-01

To investigate risk factors for Acanthamoeba keratitis amongst contact lens wearers in Scotland. Patients with Acanthamoeba keratitis in the Scottish study, all of whom wore contact lenses, were compared with 46 healthy asymptomatic contact lens-wearing controls. They were all visited at home for contact lens and environmental microbiological sampling. In addition, all 288 optical practices in the West of Scotland were polled for contact lens types and disinfecting solutions sold in 1995, and a sample, each of whom fitted more than 500 contact lenses per year, were polled for a second time. Independently, a poll was commissioned by the Eyecare Information Service in July/August 1995 to estimate the numbers of contact lens wearers in Scotland and the UK. Industry was polled for numbers of each contact lens disinfecting regimen sold in Scotland in 1995. West of Scotland, UK. All contact lens wearers among the 3 million population of the West of Scotland Health Board Areas. Risk factors for Acanthamoeba infection and recommendations for its prevention. When Acanthamoeba infection occurred, patients' home water systems were frequently (54%) found to be colonised by this amoeba. Patients more frequently washed their storage cases in tap water than controls (Pmethods (chlorine tablets or no disinfection). However further investigation showed that these methods were associated with an increased probability of rinsing the storage case in tap water, so that these two behaviours are confounded in the group studied. Failure to disinfect contact lenses, non-compliant use of chlorine tablets and/or introduction of tap water rinsing of storage cases were associated with increased risk of Acanthamoeba infection. New multipurpose solutions and hydrogen peroxide gave the lowest risk of Acanthamoeba infection, with no statistically significant difference between them. Ionic high-water content (FDA group 4) contact lenses were at increased risk of being associated with Acanthamoeba

Desempenho visual na correção de miopia com óculos e lentes de contato gelatinosas Visual performance in myopic correction with spectacles and soft contact lenses

Directory of Open Access Journals (Sweden)

Breno Barth

2008-02-01

with three different soft contact lenses [Acuvue® 2 (Vistacon J&J Vision Care Inc., USA, Biomedics® 55 (Ocular Science, USA, and Focus® 1-2 week (Ciba Vision Corporation, USA]. METHODS: An interventional prospective clinical trial studied a sample of 40 myopic patients (-1.00 to -4.50 sph, with or without astigmatism up to -0.75 cyl. Each patient had one eye randomized to visual performance evaluation. RESULTS: The Zywave aberrometer detected a over refraction and significant difference between Acuvue® 2 and Biomedics® 55 regarding spheric refractive components and spheric equivalent. Both soft contact lenses showed hypercorrection as compared to Focus® 1-2 week. Visual performance was not significantly different with spectacles and the three soft contact lenses in visual acuity and contrast sensitivity measurements. The wavefront analysis detected a significant difference in a third order aberration with and without soft contact lenses, with better visual performance with Acuvue® 2 and Biomedics® 55. CONCLUSION: In visual performance evaluation with spectacles and soft contact lenses the wavefront analysis was a more sensible measurement of visual function when compared to high contrast visual acuity and contrast sensitivity. The evaluation model of visual performance with wavefront analysis developed in this investigation may be useful for further similar studies.

Colored Contact Lens Dangers

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Colored Contact Lens Dangers

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Full Text Available ... Sep. 26, 2013 It started as an impulsive buy from a souvenir shop, but 10 hours after ... are being sold illegally," Dr. Steinemann said. Never buy colored contact lenses from a retailer that does ...

Colored Contact Lens Dangers

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Full Text Available ... not been properly fitted by an eye care professional, the lenses stuck to my eye like a ... prescription and proper fitting by an eye-care professional. Retailers that sell contacts without a prescription are ...

Colored Contact Lens Dangers

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Full Text Available ... colored contact lenses to enhance their costumes. From blood-drenched vampire eyes to glow-in-the-dark ... properly fitted may scratch the eye or cause blood vessels to grow into the cornea. Even if ...

Colored Contact Lens Dangers

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Full Text Available ... lentes de contacto de color Sep. 26, 2013 It started as an impulsive buy from a souvenir ... Can Ruin Vision Eye Makeup Safety In fact, it is illegal to sell colored contact lenses without ...

Colored Contact Lens Dangers

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Full Text Available ... to the journals may be interrupted during this time. We are working to resolve the issue quickly ... like a suction cup." Halloween is a popular time for people to use colored contact lenses to ...

Colored Contact Lens Dangers

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Full Text Available ... the United States. All contact lenses are medical devices that require a prescription and proper fitting by ... Care Apr 23, 2018 How long does it take the eye to go back to its original ...

Colored Contact Lens Dangers

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Full Text Available ... seek immediate medical attention from an ophthalmologist. Related resources: Learn how to properly care for contact lenses . ... have given blind patients some functional vision, using human embryonic stem cells. Two blind patients regained enough ...

Colored Contact Lens Dangers

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Full Text Available ... that decorative lenses do not require the same level of care or consideration as a standard contact ... By Kate Rauch In a small but intriguing study, scientists in England have given blind patients some ...

Colored Contact Lens Dangers

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Full Text Available ... Peligros asociados con los lentes de contacto de color Sep. 26, 2013 It started as an impulsive ... Halloween is a popular time for people to use colored contact lenses to enhance their costumes. From ...

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Full Text Available ... valid prescription that includes the brand name, lens measurements, and expiration date. Purchase the colored contact lenses ... with human-made versions. U.S. News Highlights the Value of Ophthalmologists APR 20, 2018 By Dan T. ...

Contact lens disinfection by ultraviolet light

International Nuclear Information System (INIS)

Dolman, P.J.; Dobrogowski, M.J.

1989-01-01

A 253.7-nm ultraviolet light with an intensity of 1,100 microW/cm2 was tested for its germicidal activity against contact lenses and storage solutions contaminated with various corneal pathogens. The exposure time necessary to reduce a concentration of organisms from 10(6)/ml to less than 10/ml was 30 seconds for Staphylococcus aureus, 60 seconds for Pseudomonas aeruginosa, and 84 seconds for Candida albicans. The time necessary to sterilize a suspension of 10(4)/ml Acanthamoeba polyphaga was less than three minutes with this technique. Four brands of soft contact lenses were exposed to ultraviolet light for over eight hours without changing their appearance, comfort, or refraction

Colored Contact Lens Dangers

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Full Text Available ... Español Eye Health / News Halloween Hazard: The Hidden Dangers of Buying Decorative Contact Lenses Without a Prescription ... be purchased over-the-counter or on the Internet," says Thomas Steinemann, MD, professor of ophthalmology at ...

Effects of Antifungal Soaked Silicone Hydrogel Contact Lenses on Candida albicans in an Agar Eye Model.

Science.gov (United States)

Phan, Chau-Minh; Bajgrowicz, Magdalena; McCanna, David J; Subbaraman, Lakshman N; Jones, Lyndon

2016-09-01

To evaluate the effects of two commercial silicone hydrogel contact lenses (CLs) soaked with natamycin (NA) or fluconazole (FL) on the growth of Candida albicans in an in vitro eye model. Three-D printed molds were used as a cast for making eye-shaped models comprising potato dextrose agar. Senofilcon A (SA) and lotrafilcon B (LB) CLs were incubated with either 2 mL of NA or FL at a concentration of 1 mg/mL for 24 hr. To simulate a fungal infection, the eye models were coated with C. albicans. The drug-soaked lenses were placed on top of the eye models. Seven experimental conditions were examined: (1) NA-SA, (2) NA-LB, (3) FL-SA, (4) FL-LB, (5) SA, (6) LB, and (7) control-no lens. At specified time points (t=1, 8, 16, 24, 48 hr), the agar eyes from each experimental condition were removed from the incubator and photographed. The yeast cells from the 24 and 48 hr time point were also analyzed using light microscopy. At 24 and 48 hr, there was considerable growth observed for all conditions except for the NA-SA and NA-LB conditions. When observed under the microscope at 24 and 48 hr, the morphology of the yeast cells in the FL-SA and SA condition were similar to that of the control (oval shaped). There was limited hyphae growth observed for LB and significant visible hyphae growth for the NA-LB group. For NA-SA, NA-LB, and FL-LB groups, the cells were significantly smaller compared with the control. For NA-SA and NA-LB, there was limited growth of C. albicans observed on the eye models even after 48 hr. Under the microscope, the cell morphology differ noticeably between each testing condition, and is dependent on drug-lens combinations.

The influence of lens power and center thickness on the intraocular pressure measured through soft lenses: a comparison of two noncontact tonometers.

Science.gov (United States)

Ogbuehi, Kelechi C

2012-06-01

To quantify the influence of soft contact lens power and thickness on the intraocular pressure (IOP). Thirty-nine young, healthy adult volunteers completed this study. One eye of each subject was randomly assigned either a +6D or a -6D high water content daily disposable lens. The other eye was fitted with the second lens. Triplicate measurements of IOP were taken before, during, and after contact lens wear. Each time, IOP was assessed in a randomized order with two noncontact tonometers. The lenses were swapped between eyes during a second session of measurements, one week later. In the first session with the +6D lenses, the average IOPs (±SDs) before, with the lenses fitted, and after the lenses were removed, were: 14.3 ± 2.9 mmHg, 17.0 ± 3.3 mmHg and 13.9 ± 3.1 mmHg, respectively, for the CT80 and 13.6 ± 3.1 mmHg, 17.1 ± 4.5 mmHg and 13.3 ± 2.9 mmHg, respectively, for the PT100. The corresponding values for the first session with the -6D lenses were: 14.3 ± 3.1 mmHg, 13.1 ± 3.1 mmHg and 14.1 ± 3.3 mmHg, respectively, for the CT80 and 13.6 ± 3.2 mmHg, 13.0 ± 3.0 mmHg and 13.6 ± 3.2 mmHg, respectively, for the PT100. IOP significantly (Psoft contact lens-induced changes were consistent between sessions but varied between tonometers. The measurement of IOP through soft contact lenses resulted in consistent, statistically significant differences in IOP, which were not uniform across tonometers and which did not appear to be solely related to the central thickness of the soft contact lenses. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Colored Contact Lens Dangers

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Full Text Available ... wear any kind of contact lens. In Butler's case, the lenses caused an infection and left her with a corneal ... A recent article from U.S. News and World Report explains what ophthalmologists are and how they can ...

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Full Text Available ... Tips & Prevention News Ask an Ophthalmologist Patient Stories Español Eye Health / News Halloween Hazard: The Hidden Dangers ... Decorative Contact Lenses Without a Prescription Leer en Español: Peligros asociados con los lentes de contacto de ...

Activity of a melimine derived peptide Mel4 against Stenotrophomonas, Delftia, Elizabethkingia, Burkholderia and biocompatibility as a contact lens coating.

Science.gov (United States)

Dutta, Debarun; Zhao, Timothy; Cheah, Kai Bing; Holmlund, Larke; Willcox, Mark D P

2017-06-01

To determine the antimicrobial activity of the melimine derived peptide Mel4 against Delftia, Stenotrophomonas, Elizabethkingia, Burkholderia and to investigate biocompatibility of Mel4 as an antimicrobial coating on contact lenses in animals and humans. In vitro antimicrobial activity of Mel4 was determined against the four Gram negative bacteria by investigating growth curves for 24h followed by viable counts to determine the minimum inhibitory concentration (MIC). Contact lenses were coated by covalently binding Mel4, characterized by amino acid analysis, and were investigated for changes in lens parameters. Safety of Mel-4 coated lenses were determined in a rabbit model of daily contralateral wear. A prospective, randomised, double-masked, contralateral, 1week daily wear human clinical trial was used to evaluate subjective responses and ocular physiology. Mel4 was active against all the bacteria tested (MIC 50 ranged from 31-1000μgml -1 ) and produced an antimicrobial surface on contact lenses. Mel4-coating resulted hydrophilic surface without any significant change in contact lens parameters, and showed no signs of cytotoxicity or ocular irritation during rabbit wear. During human clinical trial, there were no differences between Mel4 coated and uncoated contact lenses in lens performance indicators and ocular signs such as corneal fluorescein staining. Mel4 and control uncoated lenses had no differences in ocular symptoms during lens wear. Mel4 has achieved antimicrobial activity against variety of Gram negative bacteria that are often resistant to the action of cationic peptides and have been implicated in contact lens related adverse events. Mel4-coated contact lenses were safe to wear. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Release of Fluconazole from Contact Lenses Using a Novel In Vitro Eye Model.

Science.gov (United States)

Phan, Chau-Minh; Bajgrowicz, Magdalena; Gao, Huayi; Subbaraman, Lakshman N; Jones, Lyndon W

2016-04-01

Rapid drug release followed by a plateau phase is a common observation with drug delivery from contact lenses (CLs) when evaluated in a vial. The aim of this study was to compare the release of fluconazole from seven commercially available daily disposable CLs using a conventional vial-based method with a novel in vitro eye model. An eye model was created using two 3-dimensional printed molds, which were filled with polydimethylsiloxane to obtain an inexpensive model that would mimic the eyeball and eyelid. The model was integrated with a microfluidic syringe pump, and the flow-through was collected in a 12-well microliter plate. Four commercial daily disposable conventional hydrogels (nelfilcon A, omafilcon A, etafilcon A, ocufilcon B) and three silicone hydrogels (somofilcon A, narafilcon A, delefilcon A) were evaluated. These CLs were incubated with fluconazole for 24 h. The drug release was measured in a vial containing 4.8 mL of phosphate-buffered saline and in the polydimethylsiloxane eye model with a 4.8-mL tear flow across 24 h. Overall, conventional hydrogel CLs had a higher uptake and release of fluconazole than silicone hydrogel CLs (p eye model (p eye model under low tear volume was sustained and did not reach a plateau across 24 h (p eyes with fungal keratitis may have increased tearing, which would significantly accelerate drug release.

Subaru Weak Lensing Measurements of Four Strong Lensing Clusters: Are Lensing Clusters Over-Concentrated?

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Oguri, Masamune; Hennawi, Joseph F.; Gladders, Michael D.; Dahle, Haakon; Natarajan, Priyamvada; Dalal, Neal; Koester, Benjamin P.; Sharon, Keren; Bayliss, Matthew

2009-01-29

We derive radial mass profiles of four strong lensing selected clusters which show prominent giant arcs (Abell 1703, SDSS J1446+3032, SDSS J1531+3414, and SDSS J2111-0115), by combining detailed strong lens modeling with weak lensing shear measured from deep Subaru Suprime-cam images. Weak lensing signals are detected at high significance for all four clusters, whose redshifts range from z = 0.28 to 0.64. We demonstrate that adding strong lensing information with known arc redshifts significantly improves constraints on the mass density profile, compared to those obtained from weak lensing alone. While the mass profiles are well fitted by the universal form predicted in N-body simulations of the {Lambda}-dominated cold dark matter model, all four clusters appear to be slightly more centrally concentrated (the concentration parameters c{sub vir} {approx} 8) than theoretical predictions, even after accounting for the bias toward higher concentrations inherent in lensing selected samples. Our results are consistent with previous studies which similarly detected a concentration excess, and increases the total number of clusters studied with the combined strong and weak lensing technique to ten. Combining our sample with previous work, we find that clusters with larger Einstein radii are more anomalously concentrated. We also present a detailed model of the lensing cluster Abell 1703 with constraints from multiple image families, and find the dark matter inner density profile to be cuspy with the slope consistent with -1, in agreement with expectations.

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...

Polymicrobial Infection of the Cornea Due to Contact Lens Wear

Directory of Open Access Journals (Sweden)

Selçuk Sızmaz

2016-04-01

Full Text Available A 38-year-old male presented with pain and redness in his left eye. He had a history of wearing contact lenses. His ophthalmic examination revealed a large corneal ulcer with surrounding infiltrate. Cultures were isolated from the contact lenses, lens solutions, storage cases, and conjunctivae of both eyes and also corneal scrapings of the left eye. Fortified vancomycin and amikacin drops were started hourly. Culture results of conjunctivae of each eye and left cornea were positive for Pseudomonas aeruginosa; cultures from the contact lenses, lens solution and storage case of both eyes revealed Pseudomonas aeruginosa and Alcaligenes xylosoxidans. Polymerase chain reaction of the corneal scraping was positive for Acanthameoba. The topical antibiotics were changed with ones that both bacteria were sensitive to and anti-amoebic therapy was added. The patient had two recurrences following initial presentation despite intensive therapy. Keratitis occurred due to multiple pathogens; the relapsing course despite adequate therapy is potentially associated with this polymicrobial etiology.

Which soft contact lens power is better for piggyback fitting in keratoconus?

Science.gov (United States)

Romero-Jiménez, Miguel; Santodomingo-Rubido, Jacinto; Flores-Rodríguez, Patricia; González-Méijome, Jose Manuel

2013-02-01

To evaluate the impact of differente soft contact lens power in the anterior corneal curvature and regularity in subjects with keratoconus. Nineteen subjects (30 eyes) with keratoconus were included in the study. Six corneal topographies were taken with Pentacam Eye System over the naked eye and successively with soft lens (Senofilcon A) powers of -3.00, -1.50, 0.00, +1.50 and +3.00 D. Corneal measurements of mean central keratometry (MCK), maximum tangential curvature (TK), maximum front elevation (MFE) and eccentricity (Ecc) at 6 and 8 mm diameters as well as anterior corneal surface high order aberrations (i.e. total RMS, spherical- and coma-like and secondary astigmatism) were evaluated. Negative- and plano-powered soft lenses flattened (ppowered lenses did not induce any significant changes (p>0.05 in all cases) in MCK in comparison to the naked eye. The TK power decreased with negative lenses (psoft lens power in comparison to the naked eye (p>0.05 in all cases). Corneal eccentricity increased at 8 mm diameter for all lens powers (p0.05). Statistically differences were found in coma-like and secondary astigmatism (both ppowered soft contact lenses provide a flatter anterior surface in comparison to positive-powered lenses in subjects with keratoconus and thus they might be more suitable for piggyback contact lens fitting. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Conjunctival impression cytology evaluation of patients with dry eye disease using scleral contact lenses.

Science.gov (United States)

Weber, Sarah La Porta; Hazarbassanov, Rossen Mihaylov; Nasaré, Alex; Gomes, José Álvaro Pereira; Hofling-Lima, Ana Luisa

2017-06-01

To evaluate conjunctival impression cytology and HLADR expression changes after wearing scleral contact lenses (ScCLs) for moderate to severe dry eye disease (DED). Prospective interventional case series. Forty-one eyes from 25 patients with moderate to severe DED were evaluated for Esclera ScCL treatment. Best-corrected visual acuity (BCVA) and slit-lamp findings were assessed. Impression cytology specimens were obtained from DED patients at the baseline and after wearing ScCLs for 12 months. The impression cytology specimens were analyzed using morphological results score, and HLA-DR positive cells were detected and quantified. The values were compared to assess the IC changes after wearing ScCLs. Forty-one eyes from 25 patients were fitted with ScCLs to manage DED. The underlying diseases were Stevens-Johnson syndrome (22 eyes), Sjogren's syndrome (11 eyes), graft-versus-host disease (2 eyes), dry eye after keratomileusis (2 eyes) and undifferentiated ocular surface disease (4 eyes). The HE-PAS impression cytology score did not differ significantly before and after wearing ScCLs for 12 months in DED patients (p>0.05). The percentage of eyes expressing the HLA-DR antigen in the temporal conjunctiva after wearing ScCL for 12 months significantly increased in patients with Sjogren's syndrome (11.11% to 66.66%; p=0.0498). In groups with Stevens Johnson syndrome and other ocular surface disorders, we did not observe statistically significant differences (p>0.05). The ScCLs did not change the parameters used to evaluate inflammatory processes, which were measured using conjunctival impression cytology and HLA-DR expression, except in Sjogren syndrome, in which there was an unexpected increase in HLA expression. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Nonadhesive, silica nanoparticles-based brush-coated contact lens cases--compromising between ease of cleaning and microbial transmission to contact lenses.

Science.gov (United States)

Qu, Wenwen; Hooymans, Johanna M M; Qiu, Jun; de-Bont, Nik; Gelling, Onko-Jan; van der Mei, Henny C; Busscher, Henk J

2013-05-01

Surface properties of lens cases are determinant for their cleanability and for microbial transmission from lens cases to contact lenses (CLs). PEG-polymer-brush-coatings are known to decrease microbial adhesion more than other surface-coatings. Here, we applied a robust, silica nanoparticles-based brush-coating to polypropylene cases to evaluate their ease of cleaning and probability of bacterial transmission to CLs. Adhesion forces of nine bacterial strains (Pseudomonas, Staphylococci, and Serratia) to rigid CLs, polypropylene, and silica nanoparticles-based brush-coated polypropylene were measured using atomic-force-microscopy and subjected to Weibull analyses to yield bacterial transmission probabilities. Biofilms of each strain were grown in coated and uncoated cases and rinsed with a NaCl or antimicrobial lens care solution. Residual, viable organisms were quantified. Bacterial adhesion forces of all strains were significantly, up to tenfold smaller on brush-coated than on uncoated polypropylene. This yielded, higher transmission probabilities to a CL, but mild-rinsing yielded 10-100 fold higher removal of bacteria from brush-coated than from polypropylene cases. Moreover, due to weak adhesion forces, bacteria on brush-coated cases were two-to-three fold more susceptible to an antimicrobial lens care solution than on polypropylene cases. Therewith, the design of lens case surfaces is a compromise between ease of cleaning and transmission probability to CLs. Copyright © 2013 Wiley Periodicals, Inc.

Corneal cell adhesion to contact lens hydrogel materials enhanced via tear film protein deposition.

Directory of Open Access Journals (Sweden)

Claire M Elkins

Full Text Available Tear film protein deposition on contact lens hydrogels has been well characterized from the perspective of bacterial adhesion and viability. However, the effect of protein deposition on lens interactions with the corneal epithelium remains largely unexplored. The current study employs a live cell rheometer to quantify human corneal epithelial cell adhesion to soft contact lenses fouled with the tear film protein lysozyme. PureVision balafilcon A and AirOptix lotrafilcon B lenses were soaked for five days in either phosphate buffered saline (PBS, borate buffered saline (BBS, or Sensitive Eyes Plus Saline Solution (Sensitive Eyes, either pure or in the presence of lysozyme. Treated contact lenses were then contacted to a live monolayer of corneal epithelial cells for two hours, after which the contact lens was sheared laterally. The apparent cell monolayer relaxation modulus was then used to quantify the extent of cell adhesion to the contact lens surface. For both lens types, lysozyme increased corneal cell adhesion to the contact lens, with the apparent cell monolayer relaxation modulus increasing up to an order of magnitude in the presence of protein. The magnitude of this increase depended on the identity of the soaking solution: lenses soaked in borate-buffered solutions (BBS, Sensitive Eyes exhibited a much greater increase in cell attachment upon protein addition than those soaked in PBS. Significantly, all measurements were conducted while subjecting the cells to moderate surface pressures and shear rates, similar to those experienced by corneal cells in vivo.

Anomalies in the prescribing of soft contact lens power.

Science.gov (United States)

Young, Graeme; Moody, Kurt; Sulley, Anna

2009-01-01

To determine the proportion of prescribed soft lenses rounded to the nearest half diopter and any variations from country to country and between lens types. Marketing data were obtained for soft lenses supplied during a 1-year period for lenses representing each of the following categories: mid-water hydrogel (MWH), silicone hydrogel, daily disposable, and toric silicone hydrogel (TSH). The data were analyzed for several countries/regions. Spherical lenses were analyzed in the range 1.00 to 5.75 D for plus and minus powers, and toric lenses in the range 0.50 to 5.75 D. This ensured a similar number of lenses in full or half diopter powers were compared with quarter and three-quarter diopter powers, and that there was no enforced rounding due to nonavailability of powers. By comparing the proportion of lenses from the 2 power groups, the proportion of lenses rounded to the nearest half diopter was estimated. It was assumed that half the difference between the totals of the 2 power groups represented those lenses dispensed to the nearest half diopter and, therefore, dispensed inaccurately; this was termed the "rounding rate" (RR). The power distribution curve for the sphere powers spiked in half diopter steps, illustrated a bias toward prescribing full and half diopter powers. With all lenses, the RR varied widely between countries. For the MWH, this ranged from 1.7% (Canada) to 11.6% (Iberia). The RRs were 2 to 3 times higher for plus than minus power lenses, however, this also varied by country. Overall, the RRs were lower for the silicone hydrogel and daily disposable contact lenses compared with the MWH, in particular for France and Iberia. The TSH results showed the greatest consistency between countries, with RRs ranging from 3.9% (Germany) to 9.5% (Rest of Europe). Most countries showed similar or lower RRs for TSH compared with MWH although, for some countries (e.g., United Kingdom, Nordic), these were higher. There was less difference in RRs for TSH lenses

Characterization of Soft Contact Lens Edge Fitting during Daily Wear Using Ultrahigh-Resolution Optical Coherence Tomography

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Lele Cui

2018-01-01

Full Text Available Purpose. To determine conjunctival overlap over the edge of soft contact lens and to visualize the peripheral postlens tear film (PoLTF underneath soft contact lenses using ultrahigh-resolution optical coherence tomography (UHR-OCT. Methods. Twenty participants (4 males and 16 females, 23.0 ± 3.7 years were fitted with two different types of soft contact lenses randomly. The limbus with lens was imaged with the UHR-OCT at the horizontal meridian every two hours up to 6 hours during lens wear. The conjunctival overlap was ranked as the percentage of the edge covered by the conjunctiva. The frequency of occurrence for visualized peripheral PoLTF was determined. Results. The average conjunctival overlaps at insertion were 49% and 73% for galyfilcon A and balafilcon A lenses and increased significantly to 84% and 90% by 6 hours of lens wear (P<0.001. Lenses with rounded edges had more conjunctival overlap than the lenses with angled edges (P=0.014. There were significant decreases for PoLTF on the conjunctiva (P=0.014 and peripheral cornea (P=0.004 over the study period compared to insertion. The percentage of subjects with PoLTF on the conjunctiva (32.5% and peripheral cornea (36% were greater in subjects wearing balafilcon A lenses (P=0.017. Conclusions. Increased conjunctival overlap over the lens edges and reduced PoLTF underneath the peripheral region of soft contact lenses were shown during lens daily wear. The lens edge configuration may play a role in conjunctival response and peripheral PoLTF.

Keep Contacts Clean (A Minute of Health with CDC)

Centers for Disease Control (CDC) Podcasts

2014-11-20

Keratitis is a serious, sometimes blinding, eye infection often associated with poor contact lens hygiene. This podcast discusses healthy ways to care for your contact lenses.  Created: 11/20/2014 by MMWR.   Date Released: 11/20/2014.

Differential Deposition of Fluorescently Tagged Cholesterol on Commercial Contact Lenses Using a Novel In Vitro Eye Model.

Science.gov (United States)

Walther, Hendrik; Phan, Chau-Minh; Subbaraman, Lakshman N; Jones, Lyndon

2018-04-01

We evaluate the differences in lipid uptake and penetration in daily disposable (DD) contact lenses (CL) using a conventional "in-vial" method compared to a novel in vitro eye model. The penetration of fluorescently labelled 22-(N-(7-Nitrobenz-2-Oxa-1,3-Diazol-4-yl)Amino)-23,24-Bisnor-5-Cholen-3beta-Ol (NBD)-cholesterol on three silicone hydrogel (SH) and four conventional hydrogel (CH) DD CLs were investigated. CLs were incubated for 4 and 12 hours in a vial, containing 3.5 mL artificial tear solution (ATS), or were mounted on an in vitro eye-blink platform designed to simulate physiologic tear flow (2 mL/24 hours), tear volume and "simulated" blinking. Subsequently, CLs were analyzed using laser scanning confocal microscopy and ImageJ. Penetration depth and fluorescence intensities of NBD-cholesterol varied between the incubation methods as well as lens materials. Using the traditional vial incubation method, NBD-cholesterol uptake occurred equally on both sides of all lens materials. However, using our eye-blink model, cholesterol penetration was observed primarily on the anterior surface of the CLs. In general, SH lenses showed higher intensities of NBD-cholesterol than CH materials. The traditional "in-vial" incubation method exposes the CLs to an excessively high amount of ATS, which results in an overestimation for cholesterol deposition. Our model, which incorporates important ocular factors, such as intermittent air exposure, small tear volume, and physiological tear flow between blinks, provides a more natural environment for in vitro lens incubation. In vitro measurements of CLs are a common approach to predict their interactions and performance on the eye. Traditional methods, however, are rudimentary. Therefore, this study presents a novel in vitro model to evaluate CLs, which consequently will enhance elucidations of the interactions between CLs and the eye.

Antimicrobial efficacy assessment of multi-use solution to disinfect hydrophilic contact lens, in vitro

OpenAIRE

Lui,Aline Cristina Fioravanti; Netto,Adamo Lui; Silva,Cely Barreto da; Hida,Richard; Mendes,Thais Sousa; Lui,Giovana Arlene Fioravanti; Gemperli,Daniela Barbosa; Vital,Enderson Dantas

2009-01-01

PURPOSE: To evaluate the efficacy of disinfecting solutions in hydrophilic contact lenses (CL). METHODS: Two multi-use solutions denominated solution A (0.001% polyquaternium-1 and 0.0005% myristamidopropyl dimethylamine) and solution B (0.0001% polyaminopropyl biguanide) were used. The solutions were tested in hydrophilic contact lenses infected with Pseudomonas aeruginosa (ATCC27583), Staphylococcus epidermidis (ATCC1226), Klebsiella pneumoniae (ATCC13883), Staphylococcus aureus (ATCC25923)...

Customer loyalty among daily disposable contact lens wearers.

Science.gov (United States)

Patel, Neelam I; Naroo, Shehzad A; Eperjesi, Frank; Rumney, Nicholas J

2015-02-01

Optometric practices offer contact lenses as cash sale items or as part of monthly payment plans. With the contact lens market becoming increasingly competitive, patients are opting to purchase lenses from supermarkets and Internet suppliers. Monthly payment plans are often implemented to improve loyalty. This study aimed to compare behavioural loyalty between monthly payment plan members and non-members. BBR Optometry Ltd offers a monthly payment plan (Eyelife™) to their contact lens wearers. A retrospective audit of 38 Eyelife™ members (mean±SD: 42.7±15.0 years) and 30 non-members (mean±SD: 40.8±16.7 years) was conducted. Revenue and profits generated, service uptake and product sales between the two groups were compared over a fixed period of 18 months. Eyelife™ members generated significantly higher professional fee revenue (Ployalty among contact lens wearers, particularly service uptake and volume of lens purchases. Additionally the greater professional fees generated, render monthly payment plans an attractive business model and practice builder. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Rotation of lathe-cut hydrogel lenses on the eye.

Science.gov (United States)

Harris, M G; Harris, K L; Ruddell, D

1976-01-01

The rotation lathe-cut HydroCurveTM gel contact lens was measured on six eyes to evaluate the parameters that influence lens rotation and to determine if this lens could be used to correct astigmatism. Of the 72 observations made, 73.6% showed some lens rotation, and 33.4% of the sample rotated more than 5 degrees per 10 blinks. Of the observations in which rotation was noted, 88.7% were encyclorotation. These results are similar to those found for spin-cast hydrogel lenses. None of the lens parameters evaluated seemed to be related to lens rotation, whereas the eye parameters studied were. Lenses were more likely to rotate on eyes with smaller corneal diameters, smaller palpebral apertures, and corneal curvatures steeper than 4 3.00 DK (X2, N =72, p less than 0.05). Our findings indicate that some method of lens stabilization will be needed before lathe-cut hydrogel lenses can be used to effectively correct astigmatism.

Colored Contact Lens Dangers

Medline Plus

Full Text Available ... Health / News Halloween Hazard: The Hidden Dangers of Buying Decorative Contact Lenses Without a Prescription Leer en Español: Peligros asociados con los lentes de contacto de color Sep. 26, 2013 It started as an impulsive buy from a souvenir shop, but 10 hours ...

UV-vis light transmittance through tinted contact lenses and the effect of color on values.

Science.gov (United States)

Osuagwu, Uchechukwu L; Ogbuehi, Kelechi C

2014-06-01

To assess the transmittance, in the 200-700nm electromagnetic radiation spectrum, by popularly used tinted soft contact lenses (CLs). The spectra transmittances of ultraviolet (UV)-blocking (I Day Acuvue Define, Freshlook ONE DAY) and non-UV-blocking (Durasoft 3, Tutti, and NeoCosmo) tinted soft CLs were tested. The transmittance of each lens, including nine different colors of Freshlook CL was recorded on spectrophotometer, and the data used to also calculate a UV protection factor (PF) for each lens brand tested, with a higher value indicating a higher level of protection. The UV-blocking CLs significantly reduced UVC, UVB & UVA transmission and thereby meet the American National Standards Institution standard for class 2 UV blockers: a maximum of 30% transmittance of UVA and 5% transmittance of UVB wavelengths. In contrast, the Durasoft 3, Tutti, and NeoCosmo CLs demonstrated negligible UV-blockage. The Acuvue Define CL offered the greatest protection from UVC (PF=69) and UVB (PF=55), but with only 35% luminous transmittance, while the Freshlook CL (especially gemstone green) offered the best protection from UVA (PF=24) and showed about 55% translucency. Overall, the UV-blocking CLs performed equally well across the UV spectrum. Different colors of Freshlook CL transmitted statistically and clinically significantly different amounts of visible light but similar amounts of UVR. Freshlook and Acuvue Define CLs which are designated as UV-blockers significantly reduced UVR transmission to safe levels whereas Tutti, NeoCosmo and Durasoft 3 did not. Transmission within the Freshlook CL family was more dependent on color in the visible light spectrum, but not in the UV-spectrum, where the gemstone green performing best among the tested colors. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Contact Lens Safety (A Minute of Health with CDC)

Centers for Disease Control (CDC) Podcasts

2016-08-18

Contact lenses are a convenient alternative to glasses, but improper care and use can result in infections which can lead to eye damage. This podcast discusses contact lens safety.  Created: 8/18/2016 by MMWR.   Date Released: 8/18/2016.

A comparison of regimen methods for the removal and inactivation of bacteria, fungi and Acanthamoeba from two types of silicone hydrogel lenses.

Science.gov (United States)

Kilvington, Simon; Lonnen, James

2009-04-01

To compare the antimicrobial efficacy of commercial contact lens solutions when used according to the manufacturers' recommended regimens with two types of silicone hydrogel lenses. Four multipurpose contact lens care solutions were examined, representing manufacturer recommended regimens of "rub & rinse", "no rub, rinse" or "no rub, no rinse". Test organisms were Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus, Fusarium solani, Candida albicans and Acanthamoeba castellanii (trophozoites and cysts). Organisms, in the presence of organic soil, were inoculated on to Acuvue Oasys or Air Optix lenses and subjected to the solution manufacturer's recommended regimen. The number of surviving organisms on the lenses and in the soak solution was enumerated in accordance with ISO 14729. ISO 14729 dictates that for a given organism the combined average number of surviving microbes from the lenses and disinfectant soaking solution must be bacteria, fungi and Acanthamoeba with both lens types. Solutions employing "no rub, rinse" were less satisfactory but significantly better than "no rub, no rinse". Significant differences were found in organism survival on the lenses with greater numbers remaining on the Air Optix compared to Oasys (plenses. Accordingly, it would seem prudent to recommend that contact lens care systems include a rub step as part of the hygiene regimen.

An Evaluation of the Softperm Contact Lens in the Simulated Aircraft Environment

Science.gov (United States)

1991-01-01

information for future use. SPHERICAL LENSES FOR: Cosmetic Refractive Ametropia (not aphakic) may include astigmatism not in excess of 4.00 diopters which...SoftPerm- Contact Lenses are indicated for daily wear for the cor- rection of Cosmetic Refractive Ametropia (not aphakic) by persons with non

Perfil dos alunos usuários de lentes de contato do curso de Medicina da Universidade Estadual Paulista - UNESP - Botucatu Profile of medical students from the Universidade Estadual Paulista - UNESP - Botucatu, who wear contact lenses

Directory of Open Access Journals (Sweden)

Vanessa Gonçalves Vidotti

2006-04-01

-sectional survey. RESULTS: 27.4% of the students use contact lenses, and among them 94.8% use soft contact lenses and 98% have negative degree. 46.9% discard their contact lens monthly. 63.9% have an average daily use of 14 hours, 14.1% acquire the contact lenses from optician stores or at pharmacies and 46.5% of the students clean their contact lenses when they put them on and take them off. Regarding complications, 51.0% reported ocular redness; 44.5%, blurred vision; and 42.6%, foreign body sensation, whereas only 4 students reported "keratitis". CONCLUSION: We concluded that the inadequate adaptation that occurs even in users knowledgeable about this issue such as medical students, has increased the risk of complications. This fact indicates that more attention must be paid to contact lens care in order to prevent permanent visual deficit.

Gravitationally Lensed Quasars in Gaia: II. Discovery of 24 Lensed Quasars

Science.gov (United States)

Lemon, Cameron A.; Auger, Matthew W.; McMahon, Richard G.; Ostrovski, Fernanda

2018-04-01

We report the discovery, spectroscopic confirmation and preliminary characterisation of 24 gravitationally lensed quasars identified using Gaia observations. Candidates were selected in the Pan-STARRS footprint with quasar-like WISE colours or as photometric quasars from SDSS, requiring either multiple detections in Gaia or a single Gaia detection near a morphological galaxy. The Pan-STARRS grizY images were modelled for the most promising candidates and 60 candidate systems were followed up with the William Herschel Telescope. 13 of the lenses were discovered as Gaia multiples and 10 as single Gaia detections near galaxies. We also discover 1 lens identified through a quasar emission line in an SDSS galaxy spectrum. The lenses have median image separation 2.13″ and the source redshifts range from 1.06 to 3.36. 4 systems are quadruply-imaged and 20 are doubly-imaged. Deep CFHT data reveal an Einstein ring in one double system. We also report 12 quasar pairs, 10 of which have components at the same redshift and require further follow-up to rule out the lensing hypothesis. We compare the properties of these lenses and other known lenses recovered by our search method to a complete sample of simulated lenses to show the lenses we are missing are mainly those with small separations and higher source redshifts. The initial Gaia data release only catalogues all images of ˜ 30% of known bright lensed quasars, however the improved completeness of Gaia data release 2 will help find all bright lensed quasars on the sky.

Colored Contact Lens Dangers

Medline Plus

Full Text Available ... prescription. There is no such thing as a "one size fits all" contact lens. Lenses that are not properly fitted may scratch the eye or cause blood vessels to grow into the cornea. Even if you have perfect vision, you need to get an eye exam and a prescription ...

Sustained ophthalmic delivery of highly soluble drug using pH-triggered inner layer-embedded contact lens.

Science.gov (United States)

Zhu, Qiang; Cheng, Hongbo; Huo, Yingnan; Mao, Shirui

2018-06-10

In the present work the feasibility of using inner layer-embedded contact lenses (CLs) to achieve sustained release of highly water soluble drug, betaxolol hydrochloride (BH) on the ocular surface was investigated. Blend film of cellulose acetate and Eudragit S100 was selected as the inner layer, while silicone hydrogel was used as outer layer to construct inner layer-embedded contact lenses. Influence of polymer ratio in the blend film on in vitro drug release behavior in phosphate buffered solution or simulated tear fluid was studied and drug-polymer interaction, erosion and swelling of the blend film were characterized to better understand drug-release mechanism. Storage stability of the inner layer-embedded contact lenses in phosphate buffer solution was also conducted, with ignorable drug loss and negligible change in drug release pattern within 30 days. In vivo pharmacokinetic study in rabbits showed sustained drug release for over 240 h in tear fluid, indicating prolonged drug precorneal residence time. In conclusion, cellulose acetate/Eudragit S100 inner layer-embedded contact lenses are quite promising as controlled-release carrier of highly water soluble drug for ophthalmic delivery. Copyright © 2018 Elsevier B.V. All rights reserved.

Clinical evaluation of a new multi-purpose disinfecting solution in symptomatic wearers of silicone hydrogel contact lenses

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Corbin GS

2012-07-01

lower after 30 days of use by subjects using regimen 1 compared with those using regimen 2 (P ≤ 0.024. Circumlimbal conjunctival staining (sum score was significantly lower with regimen 1 (P < 0.0001. Other parameters did not show any difference between the two treatment regimens.Conclusion: This study shows that the new multi-purpose disinfecting solution is safe and effective when used by symptomatic silicone hydrogel contact lens wearers. By improving symptoms of scratchiness, burning, stinging, and comfortable wear time, and decreasing circumlimbal conjunctival staining, the new multi-purpose disinfecting solution enhances the patient's wearing experience and helps maintain optimal lens performance.Keywords: multi-purpose disinfecting solution; subjective comfort; silicone hydrogel contact lenses

Colored Contact Lens Dangers

Medline Plus

Full Text Available ... can be purchased over-the-counter or on the Internet," says Thomas Steinemann, MD, professor of ophthalmology at ... ask for a prescription. There is no such thing as a "one size fits all" contact lens. Lenses that are not properly fitted may scratch the eye or cause blood vessels to grow into ...

A study of corneal endothelial changes in soft contact lens wearers using non-contact specular microscopy

Directory of Open Access Journals (Sweden)

Renu M Magdum

2013-01-01

Full Text Available Aim: To study the corneal endothelial changes after soft contact lens wear, to correlate these changes with the duration of soft contact lens wear, and to study the pattern of use and preferences of contact lens among young adults. Materials and Methods: This observational study was carried out in 100 eyes of 50 soft contact lens users aged between 19 and 27 years. Both eyes of 50 medical students who had never worn contact lenses served as controls. Data from each subject were collected using a structured questionnaire of 24 items that included demographic profile, pattern of contact lens use, symptoms, brand name, number of years worn, and hours of daily wear. These data were analyzed using Chi square for association. Specular microscopy was done using TOPCON SP-3000P. Computerized morphometry was used to evaluate central corneal thickness, size, shape, mean cellular density, hexagonality, coefficient of variation, and polymegathism of the corneal cells . Results: It was found that central corneal thickness was 0.532 ± 0.0309 mm in lens users and 0.514 ± 0.03 mm in controls, cell density was 2570.91 ± 432.06 cells/mm 2 in lens users and 2723.17 ± 327.64 cells/mm 2 in controls, while hexagonality was 54.81 ± 39.72% in lens users and 67.65 ± 36.49% in controls. Conclusion: Despite the known effects of long duration of soft contact lens use on corneal endothelial cell morphology, this study could not draw a significant correlation between them. However, a significant difference was found in the corneal endothelial thickness, cell density, and hexagonality. Among the soft contact lens users, 62% used soft disposable type while 38% used soft extended wear contact lens. Contact lenses were preferred over spectacles for better cosmetic appearance, comfort, and wider visual field.

The effect of contact lens usage on corneal biomechanical parameters in myopic patients.

Science.gov (United States)

Cankaya, Ali B; Beyazyildiz, Emrullah; Ileri, Dilek; Ozturk, Faruk

2012-07-01

To determine and compare the corneal biomechanical properties in myopic patients who use contact lenses and those who do not use contact lenses. The study consisted of 56 myopic patients who used contact lenses (study group) and 123 myopic patients who did not use contact lenses (control group). Intraocular pressure (IOP) was measured with an ocular response analyzer (ORA) and a Goldmann applanation tonometer. Central corneal thickness was measured with an ultrasonic pachymeter. Axial length and anterior chamber depth measurements were acquired with contact ultrasound A-scan biometry. The differences in ORA parameters between study and control group participants were analyzed. The mean corneal hysteresis in study and control groups was 10.1 ± 1.6 mm Hg (6.5-15.9 mm Hg) and 9.7 ± 1.5 mm Hg (6.3-14.2 mm Hg), respectively (P = 0.16). The mean corneal resistance factor was 10.4 ± 1.9 mm Hg (4.6-15.5 mm Hg) in the study group compared with 9.6 ± 1.9 mm Hg (5.1-15.0 mm Hg) in the control group. The difference for corneal resistance factor was statistically significant (P = 0.014). There was no significant difference in corneal-compensated IOP (P = 0.24). Mean Goldmann-correlated IOP was significantly higher in the study group than in control subjects (15.8 ± 3.2 vs. 14.7 ± 3.7 mm Hg) (P = 0.044). None of the corneal biomechanical parameters was significantly correlated to duration of contact lens usage in the study group. Our results suggest that ORA-generated parameters may be different in subjects with and without contact lens usage. Further longitudinal studies need to be performed to establish the relevance of our results.

In Vitro Effect of Lysozyme on Albumin Deposition to Hydrogel Contact Lens Materials.

Science.gov (United States)

Babaei Omali, Negar; Subbaraman, Lakshman N; Heynen, Miriam; Fadli, Zohra; Coles-Brennan, Chantal; Jones, Lyndon W

2017-11-01

Albumin deposition on contact lenses could be detrimental to contact lens (CL) wear because this may increase the risk of bacterial binding and reduce comfort. Lysozyme deposition on selected lens materials would reduce albumin deposition on lenses. This study aims to determine if lysozyme deposition on CLs could act as a barrier against subsequent albumin adsorption, using an in vitro model. Six hydrogel CL materials (etafilcon A, polymacon, nelfilcon A, omafilcon A, ocufilcon B, and nesofilcon A) were evaluated. Four CLs of each type were soaked in lysozyme solution for 16 hours at 37°C. Lysozyme-coated lenses were then placed in vials with 1.5 mL of artificial tear solution containing I-labeled albumin for 16 hours at 37°C with shaking. Four uncoated lenses of each type were used as controls. Lenses soaked in radiolabeled albumin were rinsed in a phosphate-buffered saline solution, and radioactive counts were measured directly on lenses using a gamma counter. Albumin uptake on lenses was measured using a calibration curve by plotting radioactive counts versus protein concentration. Results are reported as mean ± SD. Lysozyme-coated etafilcon A lenses exhibited lower levels of deposited albumin than uncoated etafilcon A lenses (58 ± 12 vs. 84 ± 5 ng/lens; P albumin adsorption between control (uncoated) and lysozyme-coated polymacon (105 ± 10 vs. 110 ± 34 ng/lens), nelfilcon A (51 ± 7 vs. 42 ± 20 ng/lens), omafilcon A (90 ± 20 vs. 80 ± 38 ng/lens), ocufilcon B (87 ± 20 vs. 115 ± 50 ng/lens), and nesofilcon A (170 ± 29 vs. 161 ± 10 ng/lens) lens materials (P > .05). Uncoated nesofilcon A lenses deposited the highest amount of albumin when compared with other uncoated lenses (P albumin, which may potentially be beneficial to CL wearers.

Contact lenses, migraine, and allodynia

Directory of Open Access Journals (Sweden)

Ozgur Bulent Timucin

2016-01-01

Full Text Available Clinical trials and electrophysiologic studies demonstrated increased perceptual sensitivity in patients suffering from migraines. At least, one triggering factor is described in 85% of migraine patients. The aim of this report was to investigate the relationship between contact lens (CL usage and migraine attacks in two cases. Two patients who were diagnosed with migraine reported that the frequency of migraine attacks increased after they switched to using CL with different base curves (BCs. These two patients, who began using CL with different BCs experienced discomfort and dryness of the eye. The ocular complaints were followed by migraine attacks. CL intolerance was also developed during migraine attack in one of the cases. The frequency of migraine attacks decreased and allodynia relieved significantly when flatter BCs were selected. CL related stimulus could have triggered the migraine attack. CLs should be well fitted in migraine patients with allodynia.

A novel phosphorylcholine-coated contact lens for extended wear use.

Science.gov (United States)

Court, J L; Redman, R P; Wang, J H; Leppard, S W; Obyrne, V J; Small, S A; Lewis, A L; Jones, S A; Stratford, P W

2001-12-01

The preparation and characterisation of a new phosphorylcholine (PC)-coated silicone hydrogel contact lens for use in extended wear is described. The Michael-type addition of amines to acrylates forms the basis of the synthesis of a novel silicone-based macromer with hydrophilic functionality. It is demonstrated that this macromer can be combined with other silicone-based monomers, hydrophilic monomers and crosslinker to produce a contact lenses formulation. Examples of lenses with water contents of 33% and 46% are illustrated and their properties compared to other commercially available lenses. Materials with comparatively low modulus (2-4MPa) with excellent elongation to break (>200%) can be obtained using this technology. In addition to the mechanical aspects. both the oxygen and solute permeabilities of the material can be controlled by the hydrophilic: hydrophobic monomer balance in the formulation. to obtain materials with attributes suitable for extended wear use. The PC coating is achieved by means of an in-mould coating (IMC) technique that produces a uniform and stable surface as determined by staining and XPS. The coating imparts both improved lens wettability (advancing contact angle of approximately 50 with virtually no hysteresis) and lower protein adsorption relative to the uncoated lens.

Keep Contacts Clean (A Cup of Health with CDC)

Centers for Disease Control (CDC) Podcasts

For millions of Americans, contact lenses are an effective form of vision correction and a popular alternative to glasses. However, if not properly worn and cared for, they can put wearers at risk for eye infections. In this podcast, Dr. Jennifer Cope discusses the importance of proper contact lens care.

Effect of contact lens use on Computer Vision Syndrome.

Science.gov (United States)

Tauste, Ana; Ronda, Elena; Molina, María-José; Seguí, Mar

2016-03-01

To analyse the relationship between Computer Vision Syndrome (CVS) in computer workers and contact lens use, according to lens materials. Cross-sectional study. The study included 426 civil-service office workers, of whom 22% were contact lens wearers. Workers completed the Computer Vision Syndrome Questionnaire (CVS-Q) and provided information on their contact lenses and exposure to video display terminals (VDT) at work. CVS was defined as a CVS-Q score of 6 or more. The covariates were age and sex. Logistic regression was used to calculate the association (crude and adjusted for age and sex) between CVS and individual and work-related factors, and between CVS and contact lens type. Contact lens wearers are more likely to suffer CVS than non-lens wearers, with a prevalence of 65% vs 50%. Workers who wear contact lenses and are exposed to the computer for more than 6 h day(-1) are more likely to suffer CVS than non-lens wearers working at the computer for the same amount of time (aOR = 4.85; 95% CI, 1.25-18.80; p = 0.02). Regular contact lens use increases CVS after 6 h of computer work. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

Effect of Daily Contact Lens Cleaning on Ocular Adverse Events during Extended Wear.

Science.gov (United States)

Ozkan, Jerome; Rathi, Varsha M; de la Jara, Percy Lazon; Naduvilath, Thomas; Holden, Brien A; Willcox, Mark D P

2015-02-01

The purpose of the study was to assess what effect daily cleaning of contact lenses with a multipurpose disinfection solution (MPDS), during 30 nights extended wear, would have on contact lens-related adverse events. This was a prospective, open-label, randomized, controlled, parallel-group, 3-month clinical study in which 193 participants were dispensed with lotrafilcon A silicone hydrogel lenses for a 30-day extended-wear schedule and with lenses replaced monthly. Participants were randomized to a control or test group. Test subjects were required to remove lenses daily after waking, clean them with the MPDS, and reinsert the lenses. Control subjects wore lenses without removal for 30 days extended wear. Handling-related lens contamination was assessed at the baseline visit. There was no significant difference between the test and control groups for the incidence of significant corneal infiltrative events (1.3 vs. 4.9%, p = 0.368), total corneal infiltrative events (2.6 vs. 4.9%, p = 0.682), or mechanical events (1.3 vs. 2.5%, p = 1.00). The test group had greater corneal staining (p lenses) resulted in isolation of Gram-positive bacteria from 92.5% of test lenses compared with 87.5% of control lenses (p = 0.712). Gram-negative bacteria were isolated from 5% of test subjects compared with 2.5% of control subjects (p = 1.00). Fungus was isolated from 2.5% of subjects in both the test and control groups (p = 1.00). The intervention of daily morning cleaning of the lens surface with an MPDS during extended wear did not significantly influence the incidence of adverse events.

The safety and efficacy of contact lens wear in the industrial and chemical workplace.

Science.gov (United States)

Tyhurst, Keith; McNett, Ryan; Bennett, Edward

2007-11-01

The use and safety of contact lenses in the industrial and chemical workplace has often been questioned since the 1960s because of many unconfirmed reports of ocular injury resulting from contact lens wear. Because of these urban legends, contact lens wear has been banned or wearers have been required to wear additional personal protective equipment (PPE) not required of non-contact lens wearers. Literature review via Medline and Google search. Research has shown that contact lenses typically provide protective benefits that decrease the severity of ocular injury and improve worker performance. While contact lens wear contraindications do exist, in most cases, and with proper precautions, contact lens wear is still possible. Industrial and chemical companies need to establish written contact lens use policies based on current studies that have shown the safety of workplace contact lens wear when combined with the same PPE required of non-contact lens wearers. Practitioners need to discuss, with their contact lens patients, the additional responsibilities required to maintain proper lens hygiene and proper PPE in the workplace.

A clinical study of patient acceptance and satisfaction of Varilux Plus and Varilux Infinity lenses.

Science.gov (United States)

Cho, M H; Barnette, C B; Aiken, B; Shipp, M

1991-06-01

An independent study was conducted at the UAB School of Optometry to determine the clinical success with Varilux Plus (Varilux 2) and Varilux Infinity progressive addition lenses (PAL). Two hundred eighty patients (280) were fit between June 1988 and May 1989. The acceptance rate of 97.5 percent was based on the number of lenses ordered versus the number of lenses returned. Patients were contacted by telephone and asked to rate their level of satisfaction with their PALs. A chi-square (non-parametric) test revealed no statistically significant differences in levels of satisfaction with respect to gender, PAL type, or degree of presbyopia. Also, neither refractive error nor previous lens history had a measurable impact on patient satisfaction.

Impact of previous extended and daily wear schedules on signs and symptoms with high Dk lotrafilcon A lenses.

Science.gov (United States)

Chalmers, Robin L; Dillehay, Sally; Long, Bill; Barr, Joseph T; Bergenske, Peter; Donshik, Peter; Secor, Glenda; Yoakum, John

2005-06-01

This study measured the impact of previous contact lens wearing schedule on the resolution of signs and contact lens-related symptoms among wearers of lotrafilcon A lenses. One hundred forty adapted low Dk daily wear (DW) and 140 adapted low Dk extended wear (EW) subjects were enrolled and examined for 1 year (overall study length is 3 years). All subjects wore lotrafilcon A lenses on a wearing schedule of up to 30 nights continuous wear with monthly replacement of lenses. Examinations were conducted at 1 week, 1, 6, and 12 months. The former EW wearers presented at baseline with significantly higher conjunctival staining and epithelial microcysts (p Dk DW and EW wearers within 1 week as did severity of dryness during the day for the former DW wearers, in part as a result of their higher prevalence at baseline in the DW group. Subjects reported redness improved significantly by the 1-month visit. Continuous wear of high Dk silicone hydrogel lenses resulted in an improvement in ocular redness and neovascularization and dryness symptoms among subjects in this trial, regardless of their previous low Dk lens-wearing schedule. All improvements in signs and symptoms were sustained through 12 months.

Healthy Contact Lens Wear and Care

Centers for Disease Control (CDC) Podcasts

2014-02-04

In this podcast, CDC’s Dr. Jennifer Cope explains some basic steps for proper wear and care of soft contact lenses.  Created: 2/4/2014 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 2/4/2014.

Compliance and hygiene behaviour among soft contact lens wearers in the Maldives.

Science.gov (United States)

Gyawali, Rajendra; Nestha Mohamed, Fathimath; Bist, Jeewanand; Kandel, Himal; Marasini, Sanjay; Khadka, Jyoti

2014-01-01

Significant levels of non-compliance and poor hygiene among contact lens wearers have been reported previously from different parts of the world. This survey aimed at identifying the scope of hygiene and non-compliant behaviour of soft contact lens wearers in the Maldives. Established soft lens wearers attending two eye clinics in Male' city, were interviewed in office or via telephone. A set of interviewer-administered questions was used to access the subjective response on compliance and hygiene behaviour (hand and lens case hygiene, water exposure, adherence to lens replacement schedule, dozing and overnight wear, awareness of aftercare visits and reuse of disinfecting solution). Participants were also asked to rate themselves as a contact lens user based on their perceived compliance and hygiene practices. Out of 107 participants, 79 (74.8 per cent) were interviewed in the office and the rest via telephone. The majority of lens wearers were female, office workers and students, with a mean age of 20.64 ± 4.4 years. Mean duration of lens wear was 28.04 ± 8.36 months. Most of them were using spherical lenses (86.9 per cent) on a daily wear basis (96.3 per cent). Major reported forms of non-compliance were poor hand hygiene (60.7 per cent), lack of aftercare awareness (39.3 per cent), water exposure (35.5 per cent) and over-use of lenses (24.3 per cent). While females were more likely to overuse their lenses than males (p hygienic behaviour. A significant number of Maldivian contact lens wearers exhibited poor levels of hygiene and compliance with contact lenses and lens care systems. An effective educational reinforcement strategy needs to be developed to modify lens wearers' non-compliance. © 2013 The Authors. Clinical and Experimental Optometry © 2013 Optometrists Association Australia.

Effects of Silicone Hydrogel Contact Lens Application on Corneal High-order Aberration and Visual Guality in Patients with Corneal Opacities

Directory of Open Access Journals (Sweden)

Sevda Aydın Kurna

2012-03-01

Full Text Available Pur po se: Evaluation of the corneal high-order aberrations and visual quality changes after application of silicone hydrogel contact lenses in patients with corneal opacities due to various etiologies. Ma te ri al and Met hod: Fifteen eyes of 13 patients with corneal opacities were included in the study. During the ophthalmologic examination before and after contact lens application, visual acuity was measured with Snellen acuity chart and contrast sensitivity - with Bailey-Lowie Charts in letters. Aberrations were measured with corneal aberrometer (NIDEK Magellan Mapper under a naturally dilated pupil. Spherical aberration, coma, trefoil, irregular astigmatism and total high-order root mean square (RMS values were recorded. Measurements were repeated with balafilcon A lenses (PureVision 2 HD, B&L on all patients. Re sults: Patient age varied between 23 and 50 years. Two eyes had subepithelial infiltrates due to adenoviral keratitis, 1 had nebulae due to previous infections or trauma, and 2 had Salzmann’s nodular degeneration. We observed a mean increase of 1 line in visual acuity and 5 letters in contrast sensitivity with contact lenses versus glasses in the patients. Mean RMS values of spherical aberration, irregular astigmatism and total high-order aberrations decreased significantly with contact lenses. Dis cus si on: Silicone hydrogel soft contact lenses may improve visual quality by decreasing the corneal aberrations in patients with corneal opacities. (Turk J Ophthalmol 2012; 42: 97-102

Activity of a melimine derived peptide Mel4 against Stenotrophomonas, Delftia, Elizabethkingia, Burkholderia and biocompatibility as a contact lens coating

DEFF Research Database (Denmark)

Dutta, Debarun; Zhao, Timothy; Cheah, Kai Bing

2017-01-01

Purpose To determine the antimicrobial activity of the melimine derived peptide Mel4 against Delftia, Stenotrophomonas, Elizabethkingia, Burkholderia and to investigate biocompatibility of Mel4 as an antimicrobial coating on contact lenses in animals and humans. Methods In vitro antimicrobial...... activity of Mel4 was determined against the four Gram negative bacteria by investigating growth curves for 24 h followed by viable counts to determine the minimum inhibitory concentration (MIC). Contact lenses were coated by covalently binding Mel4, characterized by amino acid analysis, and were...... was active against all the bacteria tested (MIC50 ranged from 31–1000 μg ml−1) and produced an antimicrobial surface on contact lenses. Mel4-coating resulted hydrophilic surface without any significant change in contact lens parameters, and showed no signs of cytotoxicity or ocular irritation during rabbit...

A novel in-vitro method for assessing contact lens surface dewetting: Non-invasive keratograph dry-up time (NIK-DUT).

Science.gov (United States)

Marx, Sebastian; Sickenberger, Wolfgang

2017-12-01

This study was designed to develop a novel technique called non-invasive keratograph dry-up time (NIK-DUT), which used an adapted corneal topographer, to analyse in-vitro contact lens surface dewetting and the effects of combinations of lenses and lens care solutions on dewetting. Variables were assessed to optimise sensitivity and reproducibility. To validate the method, in-vitro dewetting of silicone hydrogel contact lenses (balafilcon A, comfilcon A, lotrafilcon A, lotrafilcon B and senofilcon A) was tested. All lens types were soaked in OPTI-FREE ® PureMoist ® Multipurpose Disinfecting Solution (OFPM) and Sensitive Eyes ® Saline Solution. The mean NIK-DUT, defined as drying of 25% of the placido ring measurement segments (NIK-DUT_S25), was calculated for each lens/lens solution combination and a visual map constructed representing the time and location of the dry-up event. Optimal conditions for NIK-DUT measurement included mounting onto a glass stage with a surface geometry of r=8.5mm, e=0, and measuring with high intensity red or white illumination. This method detected significant differences in contact lens dewetting with different lens soaking solutions. NIK-DUT_S25 for all lenses was longer when pre-soaked in OFPM versus saline. Visual analysis showed that dewetting of contact lenses was not uniform across surfaces and differed between test solutions. NIK-DUT is suitable for detecting differences in dewetting among various contact lenses and lens-care combinations. NIK-DUT can quantify the dewetting of large areas of lens surfaces with little subjective influence. Lens care solutions containing surface-active wetting agents were found to delay surface dewetting of silicone hydrogel lenses. Copyright © 2017. Published by Elsevier Ltd.

Clinical performance of Rose K2 soft contact lens for keratoconus

Directory of Open Access Journals (Sweden)

Ihsan Yilmaz

2017-08-01

Full Text Available AIM: To evaluate the comfort and visual performance of Rose K2 soft contact lenses in patients with keratoconus.METHODS: Fifty eyes of 50 participants were included in this cross-sectional study. Each participant received a full ophthalmologic examination involving refraction, uncorrected visual acuity(UCVA, best spectacle corrected visual acuity(BCVA, slit-lamp biomicroscopy-fundoscopy, break-up time(BUT, corneal topography, and contrast sensitivity. After contact lens was fitted best contact lens corrected visual acuity(BCLCVA, contrast sensitivity, and comfort rating via visual analogue scales(VASwere performed.RESULTS: The mean age was 26.2±6.0(range: 16 to 39y. The mean logMAR UCVA, BCVA, and BCLCVA with Rose K2 soft(in orderwere 0.61±0.37(range: 0.15-1.3, 0.42±0.32(range: 0-1.3, and 0.18±0.20(range: 0-1.3. There were significant increases in visual acuities with contact lenses(P P CONCLUSION: Rose K2 soft contact lens can improve visual acuity, contrast sensitivity with comfort in patients with keratoconus.

Comparative evaluation of Comfilcon A and Senofilcon A bandage contact lenses after transepithelial photorefractive keratectomy

Directory of Open Access Journals (Sweden)

Achyut Mukherjee

2015-01-01

Conclusion: The variation in material characteristics and lens geometry of different silicone hydrogel lenses affects their clinical characteristics in therapeutic roles. Other factors than oxygen permeability may affect pain and epithelial healing, with superior pain relief from the less permeable Senofilcon lens in this study.

First contact diagnosis and management of contact lens-related complications.

Science.gov (United States)

Fagan, Xavier J; Jhanji, Vishal; Constantinou, Marios; Amirul Islam, F M; Taylor, Hugh R; Vajpayee, Rasik B

2012-08-01

To describe the spectrum of contact lens-related problems in cases presenting to a tertiary referral eye hospital. A retrospective case record analysis of 111 eyes of 97 consecutive patients was undertaken over a period of five months at the Royal Victorian Eye and Ear Hospital, Melbourne, Australia. Contact lens-related complications (CLRC) were classified into microbial keratitis, sterile corneal infiltrates, corneal epitheliopathy and contact lens-related red eye (CLARE). Main parameters examined were nature of the first contact, clinical diagnosis, and management pattern. Forty-two percent of the initial presentations were to health care practitioners (HCPs) other than ophthalmologists. Mean duration from the onset of symptoms to presentation was 6.3 ± 10.9 days. Forty-nine percent (n = 54) of patients had an associated risk factor, most commonly overnight use of contact lenses (n = 14, 13 %). Most common diagnosis at presentation was corneal epitheliopathy (68 %) followed by sterile infiltrates (10 %), CLARE (8 %) and microbial keratitis (6 %). No significant differences were found in the pattern of treatment modalities administered by ophthalmologists and other HCPs. HCPs other than ophthalmologists are the first contact for contact lens-related problems in a significant proportion of patients. These HCPs manage the majority of CLRC by direct treatment or immediate referral.

Analysis of luminosity distributions of strong lensing galaxies: subtraction of diffuse lensed signal

Science.gov (United States)

Biernaux, J.; Magain, P.; Hauret, C.

2017-08-01

Context. Strong gravitational lensing gives access to the total mass distribution of galaxies. It can unveil a great deal of information about the lenses' dark matter content when combined with the study of the lenses' light profile. However, gravitational lensing galaxies, by definition, appear surrounded by lensed signal, both point-like and diffuse, that is irrelevant to the lens flux. Therefore, the observer is most often restricted to studying the innermost portions of the galaxy, where classical fitting methods show some instabilities. Aims: We aim at subtracting that lensed signal and at characterising some lenses' light profile by computing their shape parameters (half-light radius, ellipticity, and position angle). Our objective is to evaluate the total integrated flux in an aperture the size of the Einstein ring in order to obtain a robust estimate of the quantity of ordinary (luminous) matter in each system. Methods: We are expanding the work we started in a previous paper that consisted in subtracting point-like lensed images and in independently measuring each shape parameter. We improve it by designing a subtraction of the diffuse lensed signal, based only on one simple hypothesis of symmetry. We apply it to the cases where it proves to be necessary. This extra step improves our study of the shape parameters and we refine it even more by upgrading our half-light radius measurement method. We also calculate the impact of our specific image processing on the error bars. Results: The diffuse lensed signal subtraction makes it possible to study a larger portion of relevant galactic flux, as the radius of the fitting region increases by on average 17%. We retrieve new half-light radii values that are on average 11% smaller than in our previous work, although the uncertainties overlap in most cases. This shows that not taking the diffuse lensed signal into account may lead to a significant overestimate of the half-light radius. We are also able to measure

Fluctuation in visual acuity during soft toric contact lens wear.

Science.gov (United States)

Chamberlain, Paul; Morgan, Philip B; Moody, Kurt J; Maldonado-Codina, Carole

2011-04-01

To quantify changes in visual acuity (VA) with soft toric contact lenses as a result of lens movement and/or rotational instability caused by versional eye movements. A novel chart for vision assessment at near (40 cm) for soft toric contact lenses (VANT chart),consisting of a central, color-coded logMAR panel and eight peripheral letter targets set on a white background measuring 60 × 40 cm was constructed. In the developmental phase of the work, 10 subjects (20 eyes) wore 2 toric lenses in random order, and the impact of rapid and delayed eye versions in 8 directions of gaze on VANT acuity was investigated. In phase 2, 35 subjects (68 eyes) wore 4 toric lenses in random order, and a streamlined clinical protocol using the VANT chart was implemented. Standard assessments of toric lens fit and distance VA were also performed. Testing in the first phase showed no difference for change in VA for rapid vs. delayed version movements, (p = 0.17) but acuity reduction was greater for diagonal compared with horizontal/vertical versions (p = 0.06). As such, testing in phase 2 proceeded using rapid, diagonal versions only. In this second phase, there were differences for low-contrast distance VA measures between lens types (p = 0.02) and for both VANT baseline acuity (p = 0.03) and postversion acuity (p = 0.04), but no differences were found between lenses for magnitude of vision loss (p = 0.91), which was about one line. No relationship was established between the magnitude of vision loss and measured rotational stability (p = 0.75). This work has demonstrated that conventional approaches to measuring VA do not fully replicate the "real world" experience of soft toric lens wearers. The VANT chart has shown that VA is reduced immediately after versional eye movements and suggests that more dynamic methods of assessing visual performance should be considered for soft toric contact lens wearers, especially given the apparent inability of lens stability measurements to predict

Compliance among soft contact lens wearers.

Science.gov (United States)

Kuzman, Tomislav; Kutija, Marija Barisić; Masnec, Sanja; Jandroković, Sonja; Mrazovac, Danijela; Jurisić, Darija; Skegro, Ivan; Kalauz, Miro; Kordić, Rajko

2014-12-01

Contact lens compliance is proven to be crucial for preventing lens wear-related complications because of the interdependence of the steps in lens care regime and their influence on lens system microbial contamination. Awareness of the patients' lens handling compliance as well as correct recognition of non-compliant behaviours is the basis for creating more targeted strategies for patient education. The aim of this study was to investigate compliance among soft contact lens (SCL) wearers in different aspects of lens care handling and wearing habits. In our research 50 asymptomatic lens wearers filled out a questionnaire containing demographic data, lens type, hygiene and wearing habits, lenses and lens care system replacement schedule and self-evaluation of contact lens handling hygiene. We established criteria of compliance according to available manufacturer's recommendations, prior literature and our clinical experience. Only 2 (4%) of patients were fully compliant SCL wearers. The most common non-compliant behaviours were insufficient lens solution soaking time (62%), followed by failure to daily exchange lens case solution and showering while wearing lenses. 44% of patients reported storing lenses in saline solution. Mean lens storage case replacement was 3.6 months, with up to 78% patients replacing lens case at least once in 3 months. Average grade in self evaluating level of compliance was very good (4 +/- 0.78) (from 1-poor level of hygiene to 5-great level of hygiene). Lens wearers who reported excessive daily lens wear and more than 10 years of lens wearing experience were also found to be less compliant with other lens system care procedures. (t = -2.99, df=47, p rate, self grading was relatively high. Therefore, these results indicate the need for patient education and encouragement of better lens wearing habits and all of the lens maintenance steps at each patient visit.

Keep Contacts Clean (A Cup of Health with CDC)

Centers for Disease Control (CDC) Podcasts

2015-09-03

For millions of Americans, contact lenses are an effective form of vision correction and a popular alternative to glasses. However, if not properly worn and cared for, they can put wearers at risk for eye infections. In this podcast, Dr. Jennifer Cope discusses the importance of proper contact lens care.  Created: 9/3/2015 by MMWR.   Date Released: 9/3/2015.

Long-term clinical results: 3 years of up to 30-night continuous wear of lotrafilcon A silicone hydrogel and daily wear of low-Dk/t hydrogel lenses.

Science.gov (United States)

Bergenske, Peter; Long, Bill; Dillehay, Sally; Barr, Joseph T; Donshik, Peter; Secor, Glenda; Yoakum, John; Chalmers, Robin L

2007-03-01

To summarize results of a 3-year clinical trial assessing subjective and objective experience with lotrafilcon A silicone hydrogel (SH) lenses for up to 30 nights of continuous wear or low-Dk/t daily-wear (LDW) hydrogel lenses. Nineteen sites dispensed SH lenses to 317 subjects (286 current wearers and 31 new wearers) and 2-week replacement LDW lenses to 81 new wearers in a 3-year study. For the SH cohort, limbal redness, conjunctival redness, and corneal neovascularization improved among 23%, 21%, and 13% of eyes, respectively (PDk/t hydrogel lenses. Many biomicroscopy signs and symptoms worsened among neophytes wearing daily-wear low-Dk/t hydrogel lenses. The use of lotrafilcon A lenses may minimize many ocular changes from soft contact lens wear.

Contact lens technology to 2020 and beyond: a review of recent patent literature.

Science.gov (United States)

Papas, Eric B

2017-09-01

Contact lenses have been a common means of vision correction for more than half a century. Recent developments raise the possibility that the next several years will see the range of applications in which they are used broaden considerably, with an associated expansion in both the number and type of individuals who consider them to be a valuable option. To describe this new landscape, a review of recent patent submissions covering the period 1 January 2014 to 1 February 2017 was undertaken. The results show that in the main, areas where contact lenses will be applied include drug delivery, visual augmentation and biosensing. © 2017 Optometry Australia.

Contribution of soft lenses of various powers to the optics of a piggy-back system on regular corneas.

Science.gov (United States)

Michaud, Langis; Brazeau, Daniel; Corbeil, Marie-Eve; Forcier, Pierre; Bernard, Pierre-Jean

2013-12-01

This study aims to report on the measured in vivo contribution of soft lenses of various powers to the optics of a piggyback system (PBS). This prospective, non-dispensing clinical study was conducted on regular wearers of contact lenses who showed regular corneal profiles. Subjects were masked to the products used. The study involved the use of a spherical soft lens of three different powers in a PBS, used as a carrier for a rigid gas permeable lens. Baseline data were collected and soft lenses were then fitted on both eyes of each subject. Both lenses were assessed for position and movement. Over-refraction was obtained. Soft lens power contribution to the optics (SLPC) of a PBS system was estimated by computing initial ametropia, lacrymal lens, rigid lens powers and over-refraction. A set of data on one eye was kept, for each subject, for statistical analysis. Thirty subjects (12 males, 18 females), aged 24.4 (±4.5) years, were enrolled. The use of plus powered soft lenses enhanced initial RGP lens centration. Once optimal fit was achieved, all lenses showed normal movement. SLPC represented 21.3% of the initial soft lens power when using a -6.00 carrier, and 20.6% for a +6.00. A +0.50 did not contribute to any power induced in the system. These results are generally in accordance with theoretical model developed in the past. On average, except for the low-powered carrier, the use of a spherical soft lens provided 20.9% of its marked power. To achieve better results, the use of a plus-powered carrier is recommended. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Citation parameters of contact lens-related articles published in the ophthalmic literature.

Science.gov (United States)

Cardona, Genís; Sanz, Joan P

2014-09-01

This study aimed at exploring the citation parameters of contact lenses articles published in the Ophthalmology thematic category of the Journal Citation Reports (JCR). The Thompson Reuters Web of Science database was accessed to record bibliometric information and citation parameters of all journals listed under the Ophthalmology area of the 2011 JCR edition, including the journals with main publication interests in the contact lens field. In addition, the same database was used to unveil all contact lens-related articles published in 2011 in the same thematic area, whereupon differences in citation parameters between those articles published in contact lens and non-contact lens-related journals were explored. Significant differences in some bibliometric indicators such as half-life and overall citation count were found between contact lens-related journals (shorter half-life and fewer citations) and the median values for the Ophthalmology thematic area of the JCR. Visual examination of all Ophthalmology journals uncovered a total of 156 contact lens-related articles, published in 28 different journals, with 27 articles each for Contact Lens & Anterior Eye, Eye & Contact Lens, and Optometry and Vision Science. Significant differences in citation parameters were encountered between those articles published in contact lens and non-contact lens source journals. These findings, which disclosed contact lenses to be a fertile area of research, may be of interest to researchers and institutions. Differences in bibliometric indicators are of relevance to avoid unwanted bias when conducting between- and within-discipline comparisons of articles, journals, and researchers.

Corneal confocal microscopy and dry eye findings in contact lens discomfort patients.

Science.gov (United States)

Dogan, Aysun Sanal; Gurdal, Canan; Arslan, Nese

2018-02-01

To evaluate the corneal confocal microscopy and dry eye findings in patients with contact lens discomfort. The study included 3 groups of participants: Contact lens wearers using silicone hydrogel soft contact lenses who are symptomatic (CLD, n=15) or asymptomatic (ACL, n=11) and non-wearers as controls (n=14). Duration of contact lens wear, Ocular Surface Disease Index (OSDI) questionnaire responses, fluorescein tear break-uptime (FBUT), and corneal confocal microscopy findings were recorded. Mean age was 25.7±8.2 years and male/female ratio was 7/33. Demographic findings were similar regarding the groups. CLD patients had a longer lens use history than ACL (median 5 vs 2 years, pCLD group than ACL or controls (pCLD group, compared to controls and ACL (pCLD group compared to controls but similar to ACL (pCLD group than the ACL (p=0.014). Patients with CLD had been wearing contact lenses for longer than those without symptoms. OSDI and FBUT scores were worse in CLD patients. In contact lens discomfort patients, there were increased dendritiform cells, indicating intensified inflammatory status of the cornea. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Cytokine changes in tears and relationship to contact lens discomfort.

Science.gov (United States)

Willcox, Mark D P; Zhao, Zhenjun; Naduvilath, Thomas; Lazon de la Jara, Percy

2015-01-01

To determine the reproducibility of a multiplex bead assay for measuring cytokines in tears and correlations between ocular discomfort with or without contact lens wear and the concentration of cytokines in tears. Ninety participants (divided into two groups) were enrolled in this prospective study. They were asked to rate their ocular comfort and collect their tears in the morning and just before sleep for 10 days with or without contact lenses. The participants collected their tears using a glass microcapillary tube for both stages. Galyfilcon A lenses were worn on a daily disposable basis during the contact lens stage, and comfort scores and tears were collected before lens insertion and prior to lens removal at the end of the day. Tears were analyzed for cytokine concentrations using a 27-plex multibead assay. Correlations were sought between cytokine concentrations and comfort. There was a significant (p-0.5 Log pg/ml, p-0.2 Log pg/ml, ptears was correlated to ocular comfort, but this was not changed by contact lens wear. Ocular comfort during the day is magnified by contact lens wear. However, the increase in the change in comfort during lens wear was not associated with changes in 15 cytokines in the tear film.

Additive manufacturing of tunable lenses

Science.gov (United States)

Schlichting, Katja; Novak, Tobias; Heinrich, Andreas

2017-02-01

Individual additive manufacturing of optical systems based on 3D Printing offers varied possibilities in design and usage. In addition to the additive manufacturing procedure, the usage of tunable lenses allows further advantages for intelligent optical systems. Our goal is to bring the advantages of additive manufacturing together with the huge potential of tunable lenses. We produced tunable lenses as a bundle without any further processing steps, like polishing. The lenses were designed and directly printed with a 3D Printer as a package. The design contains the membrane as an optical part as well as the mechanical parts of the lens, like the attachments for the sleeves which contain the oil. The dynamic optical lenses were filled with an oil. The focal length of the lenses changes due to a change of the radius of curvature. This change is caused by changing the pressure in the inside of the lens. In addition to that, we designed lenses with special structures to obtain different areas with an individual optical power. We want to discuss the huge potential of this technology for several applications. Further, an appropriate controlling system is needed. Wéll show the possibilities to control and regulate the optical power of the lenses. The lenses could be used for illumination tasks, and in the future, for individual measurement tasks. The main advantage is the individuality and the possibility to create an individual design which completely fulfills the requirements for any specific application.

Contact Lens-Induced Discomfort and Protein Changes in Tears.

Science.gov (United States)

Masoudi, Simin; Stapleton, Fiona Jane; Willcox, Mark Duncan Perry

2016-08-01

Ocular discomfort is among the main causes of contact lens wear discontinuation. This study investigated the association between subjective ocular comfort ratings and diurnal changes in tear protein concentrations with and without contact lens wear. The study was a prospective, open-label, single-group two-staged investigation. Basal tears were collected from 30 experienced contact lens wearers twice a day (morning and evening) using a noninvasive method without lens wear (stage 1) and during wear of Etafilcon A contact lenses (stage 2) for 7 to 10 days. Subjects rated their ocular comfort on a scale of 1 to 100 (with 100 as extremely comfortable) at each time of tear collection. Tears were analyzed using liquid quadrupole mass spectrometry in conjunction with selected reaction monitoring (SRM) method. End-of-day comfort was reduced when wearing lenses (87.8 ± 14.3 AM vs. 79.2 ± 16.6 PM) compared to no lens wear (88.3 ± 12.6 AM vs. 84.7 ± 13.3 PM) (AM vs. PM, p tears (p < 0.05, r = -0.29). Only the absolute concentration of prolactin-induced protein correlated with subjective comfort ratings. Taking into consideration that prolactin-induced protein can be associated with disruption in water transport in lacrimal glands, our findings may indicate that changes to aqueous secretion are associated with contact lens discomfort.

Nanofocusing refractive X-ray lenses

Energy Technology Data Exchange (ETDEWEB)

Boye, Pit

2010-02-05

This thesis is concerned with the optimization and development of the production of nanofocusing refractive X-ray lenses. These optics made of either silicon or diamond are well-suited for high resolution X-ray microscopy. The goal of this work is the design of a reproducible manufacturing process which allows the production of silicon lenses with high precision, high quality and high piece number. Furthermore a process for the production of diamond lenses is to be developed and established. In this work, the theoretical basics of X-rays and their interaction with matter are described. Especially, aspects of synchrotron radiation are emphasized. Important in X-ray microscopy are the different optics. The details, advantages and disadvantages, in particular those of refractive lenses are given. To achieve small X-ray beams well beyond the 100 nm range a small focal length is required. This is achieved in refractive lenses by moving to a compact lens design where several single lenses are stacked behind each other. The, so-called nanofocusing refractive lenses (NFLs) have a parabolic cylindrical shape with lateral structure sizes in the micrometer range. NFLs are produced by using micro-machining techniques. These micro-fabrication processes and technologies are introduced. The results of the optimization and the final fabrication process for silicon lenses are presented. Subsequently, two experiments that are exemplary for the use of NFLs, are introduced. The rst one employs a high-resolution scanning fluorescence mapping of a geological sample, and the second one is a coherent x-ray diffraction imaging (CXDI) experiment. CXDI is able to reconstruct the illuminated object from recorded coherent diffraction patterns. In a scanning mode, referred to as ptychography, this method is even able to reconstruct the illumination and the object simultaneously. Especially the reconstructed illumination and the possibility of computed propagation of the wave field along the

Nanofocusing refractive X-ray lenses

International Nuclear Information System (INIS)

Boye, Pit

2010-01-01

This thesis is concerned with the optimization and development of the production of nanofocusing refractive X-ray lenses. These optics made of either silicon or diamond are well-suited for high resolution X-ray microscopy. The goal of this work is the design of a reproducible manufacturing process which allows the production of silicon lenses with high precision, high quality and high piece number. Furthermore a process for the production of diamond lenses is to be developed and established. In this work, the theoretical basics of X-rays and their interaction with matter are described. Especially, aspects of synchrotron radiation are emphasized. Important in X-ray microscopy are the different optics. The details, advantages and disadvantages, in particular those of refractive lenses are given. To achieve small X-ray beams well beyond the 100 nm range a small focal length is required. This is achieved in refractive lenses by moving to a compact lens design where several single lenses are stacked behind each other. The, so-called nanofocusing refractive lenses (NFLs) have a parabolic cylindrical shape with lateral structure sizes in the micrometer range. NFLs are produced by using micro-machining techniques. These micro-fabrication processes and technologies are introduced. The results of the optimization and the final fabrication process for silicon lenses are presented. Subsequently, two experiments that are exemplary for the use of NFLs, are introduced. The rst one employs a high-resolution scanning fluorescence mapping of a geological sample, and the second one is a coherent x-ray diffraction imaging (CXDI) experiment. CXDI is able to reconstruct the illuminated object from recorded coherent diffraction patterns. In a scanning mode, referred to as ptychography, this method is even able to reconstruct the illumination and the object simultaneously. Especially the reconstructed illumination and the possibility of computed propagation of the wave field along the

Castor oil and mineral oil nanoemulsion: development and compatibility with a soft contact lens.

Science.gov (United States)

Katzer, Tatiele; Chaves, Paula; Bernardi, Andressa; Pohlmann, Adriana R; Guterres, Silvia S; Beck, Ruy C R

2014-03-01

The non-invasive ophthalmic therapy has a drawback: low residence time in the eye socket. Nanoparticles and contact lenses have been studied as promising ocular drug delivery systems. To develop a nanoemulsion and evaluate its compatibility with a soft contact lens as a potential strategy for ocular delivery. The formulations were developed by spontaneous emulsification and fully characterized. Two drops of nanoemulsion were instilled on the surface of a commercial contact lens and its transparency was measured using a UV-Vis spectrophotometer. Before and after the instillation of the drops, the morphology (scanning electron microscopy - SEM) and ion permeability of the lenses were analyzed. The formulations had a mean particle size of 234 nm, polydispersity below 0.16, zeta potential of -8.56 ± 3.49 mV, slightly acid pH, viscosity ≈1.2 mPa s(-1) and spherical-shaped particles. Nanoemulsion was non-irritant (hen's egg test-chorioallantoic membrane), which was confirmed by the cytotoxicity studies in the SIRC cell cultures. After instillation, SEM analysis showed nanodroplets inside and on the surface of the lenses, although their transparency remained near 100%. No significant differences were found between lens ion permeability coefficients before and after instillation. Formulations presented appropriate physicochemical characteristics and suitability for ocular application. The contact lens remained transparent and ion-permeable after association with the formulation.

Treatment, material, care, and patient-related factors in contact lens-related dry eye.

Science.gov (United States)

Ramamoorthy, Padmapriya; Sinnott, Loraine T; Nichols, Jason J

2008-08-01

To examine the effect of general contact lens and material characteristics, care solutions, treatment, and patient-related factors on contact lens-related dry eye. The data were derived from the Contact Lens and Dry Eye Study, designed as a cross-sectional and nested case-control study including 360 subjects. In separate statistical models, logistic regression was used to examine general contact lens characteristics, specific hydrogel lens materials, care solutions, and patient-related factors associated with dry eye status (controlled for age, gender, and current treatments). Several factors were significantly associated with dry eye, including treatment factors such as a recent contact lens refitting (odds ratios [OR] = 5.75, 95% confidence intervals [CI] = 2.14 to 15.46) and use of artificial tears/rewetting drops (OR = 1.09, 95% CI = 1.02 to 1.16), in addition, currently worn materials including Food and Drug Administration (FDA) group II (OR = 2.98, 95% CI = 1.14 to 6.19) and IV (OR = 1.87, 95% CI = 1.08 to 3.24). Significant patient-related factors included decreased overall satisfaction (OR = 3.57, 95% CI = 2.08 to 5.88,), dry eye in the absence of contact lens wear (OR = 6.54, 95% CI = 2.57 to 16.62), reduced daily lens wear duration (OR = 1.16, 95% CI = 1.06 to 1.26), and reduced ability to wear lenses as long as desired (OR = 2.44, 95% CI = 1.30 to 4.54). Care solutions were not associated with contact lens-related dry eye. The strong association of common treatment factors with dry eye status in contact lens wearers suggests that these treatments are not entirely effective. The use of high water content materials was strongly related to dry eye in lens wearers, whereas care solutions were not. Contact lens-related dry eye was also associated with several patient-related factors such as greater ocular discomfort (without lenses), dissatisfaction, and inability to wear lenses for desired durations.

Statistics of gravitational lenses. III. Astrophysical consequences of quasar lensing

International Nuclear Information System (INIS)

Ostriker, J.P.; Vietri, M.

1986-01-01

The method of Schmidt and Green (1983) for calculating the luminosity function of quasars is combined with gravitational-lensing theory to compute expected properties of lensed systems. Multiple quasar images produced by galaxies are of order 0.001 of the observed quasars, with the numbers over the whole sky calculated to be (0.86, 120, 1600) to limiting B magnitudes of (16, 19, 22). The amount of false evolution is small except for an interesting subset of apparently bright, large-redshift objects for which minilensing by starlike objects may be important. Some of the BL Lac objects may be in this category, with the galaxy identified as the parent object really a foreground object within which stars have lensed a background optically violent variable quasar. 24 references

Gravitational lensing

CERN Document Server

Dodelson, Scott

2017-01-01

Gravitational lensing is a consequence of general relativity, where the gravitational force due to a massive object bends the paths of light originating from distant objects lying behind it. Using very little general relativity and no higher level mathematics, this text presents the basics of gravitational lensing, focusing on the equations needed to understand the phenomena. It then applies them to a diverse set of topics, including multiply imaged objects, time delays, extrasolar planets, microlensing, cluster masses, galaxy shape measurements, cosmic shear, and lensing of the cosmic microwave background. This approach allows undergraduate students and others to get quickly up to speed on the basics and the important issues. The text will be especially relevant as large surveys such as LSST and Euclid begin to dominate the astronomical landscape. Designed for a one semester course, it is accessible to anyone with two years of undergraduate physics background.

Biconvex intraocular lenses and Nd:YAG capsulotomy: Experimental comparison of surface damage with different poly(methyl methacrylate) formulations

Energy Technology Data Exchange (ETDEWEB)

Downing, J.E.; Alberhasky, M.T. (Greenview Hospital, Bowling Green, KY (USA))

1990-11-01

Biconvex posterior chamber lenses have optical advantages and decrease the risk of capsular opacification, but they are more likely to be pitted during ND:YAG capsulotomy because of apposition of the lens to the capsule. This study reports the likelihood of surface damage to different formulations of poly(methyl methacrylate) at the energy levels required to open posterior capsules. Molded lenses are more easily damaged than higher molecular weight lathe-cut materials (P less than .01), as expected. However, by keeping energy output low, even injection-molded lenses showed minimal damage, with mean pit size 39 +/- 39 microns at 1 mJ. By using a converging contact lens, low power, and keeping the focus behind the capsule, damage to all materials tested should be clinically insignificant.

30 CFR 18.30 - Windows and lenses.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Windows and lenses. 18.30 Section 18.30 Mineral... § 18.30 Windows and lenses. (a) MSHA may waive testing of materials for windows or lenses except headlight lenses. When tested, material for windows or lenses shall meet the test requirements prescribed in...

Measurement accuracy of a stressed contact lens during its relaxation period

Science.gov (United States)

Compertore, David C.; Ignatovich, Filipp V.

2018-02-01

We examine the dioptric power and transmitted wavefront of a contact lens as it releases its handling stresses. Handling stresses are introduced as part of the contact lens loading process and are common across all contact lens measurement procedures and systems. The latest advances in vision correction require tighter quality control during the manufacturing of the contact lenses. The optical power of contact lenses is one of the critical characteristics for users. Power measurements are conducted in the hydrated state, where the lens is resting inside a solution-filled glass cuvette. In a typical approach, the contact lens must be subject to long settling times prior to any measurements. Alternatively, multiple measurements must be averaged. Apart from potential operator dependency of such approach, it is extremely time-consuming, and therefore it precludes higher rates of testing. Comprehensive knowledge about the settling process can be obtained by monitoring multiple parameters of the lens simultaneously. We have developed a system that combines co-aligned a Shack-Hartmann transmitted wavefront sensor and a time-domain low coherence interferometer to measure several optical and physical parameters (power, cylinder power, aberrations, center thickness, sagittal depth, and diameter) simultaneously. We monitor these parameters during the stress relaxation period and show correlations that can be used by manufacturers to devise methods for improved quality control procedures.

Gabor lenses

International Nuclear Information System (INIS)

Mobley, R.M.; Gamml, G.; Maschke, A.W.

1979-01-01

Stable operation of Gabor lenses has been reported by at least three experimental groups. At Brookhaven, several lens designs have been tried since February, 1978 with very good results. The lens concept is simple, operation is less complicated than anticipated, and the focussing strengths attainable make them very attractive alternatives to magnetic focussing for heavy ion beams at low energies. Results obtained with five different configurations are presented. The lenses work well, concern is now with fine details of their beam-optical performance

Bacterial Adhesion Forces to Ag-Impregnated Contact Lens Cases and Transmission to Contact Lenses

NARCIS (Netherlands)

Qu, Wenwen; Busscher, Henk J.; van der Mei, Henny C.; Hooymans, Johanna M. M.

Purpose: To measure adhesion forces of Pseudomonas aeruginosa, Staphylococcus aureus, and Serratia marcescens to a rigid contact lens (CL), standard polypropylene, and Ag-impregnated lens cases using atomic force microscopy and determine bacterial transmission from lens case to CL. Methods: Adhesion

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.

Gravitational lenses and cosmological evolution

International Nuclear Information System (INIS)

Peacock, J.A.

1982-01-01

The effect of gravitational lensing on the apparent cosmological evolution of extragalactic radio sources is investigated. Models for a lens population consisting of galaxies and clusters of galaxies are constructed and used to calculate the distribution of amplification factors caused by lensing. Although many objects at high redshifts are predicted to have flux densities altered by 10 to 20 per cent relative to a homogeneous universe, flux conservation implies that de-amplification is as common as amplification. The effects on cosmological evolution as inferred from source counts and redshift data are thus relatively small; the slope of the counts is not large enough for intrinsically rare lensing events of high amplitude to corrupt observed samples. Lensing effects may be of greater importance for optically selected quasars, where lenses of mass as low as approximately 10 -4 solar mass can cause large amplifications. (author)

BAYESIAN INFERENCE OF CMB GRAVITATIONAL LENSING

Energy Technology Data Exchange (ETDEWEB)

Anderes, Ethan [Department of Statistics, University of California, Davis, CA 95616 (United States); Wandelt, Benjamin D.; Lavaux, Guilhem [Sorbonne Universités, UPMC Univ Paris 06 and CNRS, UMR7095, Institut d’Astrophysique de Paris, F-75014, Paris (France)

2015-08-01

The Planck satellite, along with several ground-based telescopes, has mapped the cosmic microwave background (CMB) at sufficient resolution and signal-to-noise so as to allow a detection of the subtle distortions due to the gravitational influence of the intervening matter distribution. A natural modeling approach is to write a Bayesian hierarchical model for the lensed CMB in terms of the unlensed CMB and the lensing potential. So far there has been no feasible algorithm for inferring the posterior distribution of the lensing potential from the lensed CMB map. We propose a solution that allows efficient Markov Chain Monte Carlo sampling from the joint posterior of the lensing potential and the unlensed CMB map using the Hamiltonian Monte Carlo technique. The main conceptual step in the solution is a re-parameterization of CMB lensing in terms of the lensed CMB and the “inverse lensing” potential. We demonstrate a fast implementation on simulated data, including noise and a sky cut, that uses a further acceleration based on a very mild approximation of the inverse lensing potential. We find that the resulting Markov Chain has short correlation lengths and excellent convergence properties, making it promising for applications to high-resolution CMB data sets in the future.

Slit-lamp management in contact lenses laboratory classes: learning upgrade with monitor visualization of webcam video recordings

Science.gov (United States)

Arines, Justo; Gargallo, Ana

2014-07-01

The training in the use of the slit lamp has always been difficult for students of the degree in Optics and Optometry. Instruments with associated cameras helps a lot in this task, they allow teachers to observe and control if the students evaluate the eye health appropriately, correct use errors and show them how to do it with a visual demonstration. However, these devices are more expensive than those that do not have an integrated camera connected to a display unit. With the aim to improve students' skills in the management of slit lamp, we have adapted USB HD webcams (Microsoft Lifecam HD-5000) to the objectives of the slit lamps available in our contact lenses laboratory room. The webcams are connected to a PC running Linux Ubuntu 11.0; therefore that is a low-cost device. Our experience shows that single method has several advantages. It allows us to take pictures with a good quality of different conditions of the eye health; we can record videos of eye evaluation and make demonstrations of the instrument. Besides it increases the interactions between students because they could see what their colleagues are doing and take conscious of the mistakes, helping and correcting each others. It is a useful tool in the practical exam too. We think that the method supports the training in optometry practice and increase the students' confidence without a huge outlay.

Cosmology with weak lensing surveys

International Nuclear Information System (INIS)

Munshi, Dipak; Valageas, Patrick; Waerbeke, Ludovic van; Heavens, Alan

2008-01-01

Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening matter. The distortions are due to fluctuations in the gravitational potential, and are directly related to the distribution of matter and to the geometry and dynamics of the Universe. As a consequence, weak gravitational lensing offers unique possibilities for probing the Dark Matter and Dark Energy in the Universe. In this review, we summarise the theoretical and observational state of the subject, focussing on the statistical aspects of weak lensing, and consider the prospects for weak lensing surveys in the future. Weak gravitational lensing surveys are complementary to both galaxy surveys and cosmic microwave background (CMB) observations as they probe the unbiased non-linear matter power spectrum at modest redshifts. Most of the cosmological parameters are accurately estimated from CMB and large-scale galaxy surveys, so the focus of attention is shifting to understanding the nature of Dark Matter and Dark Energy. On the theoretical side, recent advances in the use of 3D information of the sources from photometric redshifts promise greater statistical power, and these are further enhanced by the use of statistics beyond two-point quantities such as the power spectrum. The use of 3D information also alleviates difficulties arising from physical effects such as the intrinsic alignment of galaxies, which can mimic weak lensing to some extent. On the observational side, in the next few years weak lensing surveys such as CFHTLS, VST-KIDS and Pan-STARRS, and the planned Dark Energy Survey, will provide the first weak lensing surveys covering very large sky areas and depth. In the long run even more ambitious programmes such as DUNE, the Supernova Anisotropy Probe (SNAP) and Large-aperture Synoptic Survey Telescope (LSST) are planned. Weak lensing of diffuse components such as the CMB and 21 cm emission can also

Cosmology with weak lensing surveys

Energy Technology Data Exchange (ETDEWEB)

Munshi, Dipak [Institute of Astronomy, Madingley Road, Cambridge, CB3 OHA (United Kingdom); Astrophysics Group, Cavendish Laboratory, Madingley Road, Cambridge CB3 OHE (United Kingdom)], E-mail: munshi@ast.cam.ac.uk; Valageas, Patrick [Service de Physique Theorique, CEA Saclay, 91191 Gif-sur-Yvette (France); Waerbeke, Ludovic van [University of British Columbia, Department of Physics and Astronomy, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Heavens, Alan [SUPA - Scottish Universities Physics Alliance, Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)

2008-06-15

Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening matter. The distortions are due to fluctuations in the gravitational potential, and are directly related to the distribution of matter and to the geometry and dynamics of the Universe. As a consequence, weak gravitational lensing offers unique possibilities for probing the Dark Matter and Dark Energy in the Universe. In this review, we summarise the theoretical and observational state of the subject, focussing on the statistical aspects of weak lensing, and consider the prospects for weak lensing surveys in the future. Weak gravitational lensing surveys are complementary to both galaxy surveys and cosmic microwave background (CMB) observations as they probe the unbiased non-linear matter power spectrum at modest redshifts. Most of the cosmological parameters are accurately estimated from CMB and large-scale galaxy surveys, so the focus of attention is shifting to understanding the nature of Dark Matter and Dark Energy. On the theoretical side, recent advances in the use of 3D information of the sources from photometric redshifts promise greater statistical power, and these are further enhanced by the use of statistics beyond two-point quantities such as the power spectrum. The use of 3D information also alleviates difficulties arising from physical effects such as the intrinsic alignment of galaxies, which can mimic weak lensing to some extent. On the observational side, in the next few years weak lensing surveys such as CFHTLS, VST-KIDS and Pan-STARRS, and the planned Dark Energy Survey, will provide the first weak lensing surveys covering very large sky areas and depth. In the long run even more ambitious programmes such as DUNE, the Supernova Anisotropy Probe (SNAP) and Large-aperture Synoptic Survey Telescope (LSST) are planned. Weak lensing of diffuse components such as the CMB and 21 cm emission can also

[Ocular and visual alterations in computer workers contact lens wearers: scoping review].

Science.gov (United States)

Tauste Francés, Ana; Ronda-Pérez, Elena; Seguí Crespo, María del Mar

2014-01-01

The high number of computer workers wearing contact lenses raises the question whether the sum of these two risk factors for eye health may cause a worsening of Computer Vision Syndrome. The aim of this review is to synthesize the knowledge about ocular and visual alterations related with computer use in contact lens wearers. International review of scientific papers (2003-2013) in Spanish and English, using Scoping Review method, in Medline through PubMed and in Scopus. The initial search provided 114 references, after applying inclusion/exclusion criteria six of them were included. All of them reveal that symptoms when using computer are more prevalent in contact lens wearers, with values of symptoms presentation prevalence ranging from 95.0% to 16.9% in wearers and from 57.5% to 9.9% in non-wearers, and four times more likely to develop dry eye [OR: 4.07 (95% CI: 3.52 to 4.71)]. Computer workers suffer more ocular and visual disturbances if they also are contact lens users, but studies are few and non conclusive. Likewise, further research regarding contact lens type and their conditions of use, both in symptoms and tear quality and ocular surface are needed. Silicone hydrogel lenses are associated with more comfort.

Gravitational lenses

International Nuclear Information System (INIS)

Turner, E.L.

1989-01-01

The author discusses how gravitational lens studies is becoming a major focus of extragalactic astronomy and cosmology. This review is organized into five parts: an overview of the observational situation, a look at the state of theoretical work on lenses, a detailed look at three recently discovered types of lensing phenomena (luminous arcs, radio rings, quasar-galaxy associations), a review of progress on two old problems in lens studies (deriving unique lens mass distribution models, measurements of differential time delays), and an attempt to look into the future of lens studies

Influence of day and night wear on surface properties of silicone hydrogel contact lenses and bacterial adhesion

NARCIS (Netherlands)

Vermeltfoort, Pit B. J.; Rustema-Abbing, Minie; de Vries, Joop; Bruinsma, Gerda M; Busscher, Henk J.; van der Linden, Matthijs L; Hooymans, Johanna MM; van der Mei, Henny C.

Purpose: The aim of this study was to determine the effect of continuous wear on physicochemical surface properties of silicone hydrogel (S-H) lenses and their susceptibility to bacterial adhesion. Methods: In this study, volunteers wore 2 pairs of either "lotrafilcon A" or "balafilcon A" S-H

Influence of Day and Night Wear on Surface Properties of Silicone Hydrogel Contact Lenses and Bacterial Adhesion

NARCIS (Netherlands)

Vermeltfoort, P; Rustema-Abbing, Minie; de Vries, Joop; Bruinsma, Gerda M.; Busscher, Henk J.; Van der Linden, Matthijs L.; Hooymans, Johanna M. M.; Van der Mei, Henny C.

Purpose: The aim of this study was to determine the effect of continuous wear on physicochemical surface properties of silicone hydrogel (S-H) lenses and their susceptibility to bacterial adhesion. Methods: In this study, volunteers wore 2 pairs of either "lotrafilcon A" or "balafilcon A" S-H

CMB lensing and giant rings

Energy Technology Data Exchange (ETDEWEB)

Rathaus, Ben; Itzhaki, Nissan, E-mail: nitzhaki@post.tau.ac.il, E-mail: ben.rathaus@gmail.com [Raymond and Beverly Sackler Faculty of Exact Sciences, School of Physics and Astronomy, Tel-Aviv University, Ramat-Aviv, 69978 (Israel)

2012-05-01

We study the CMB lensing signature of a pre-inationary particle (PIP), assuming it is responsible for the giant rings anomaly that was found recently in the WMAP data. Simulating Planck-like data we find that generically the CMB lensing signal to noise ratio associated with such a PIP is quite small and it would be difficult to cross correlate the temperature giant rings with the CMB lensing signal. However, if the pre-inationary particle is also responsible for the bulk flow measured from the local large scale structure, which happens to point roughly at the same direction as the giant rings, then the CMB lensing signal to noise ratio is fairly significant.

Racial Variations in Interfacial Behavior of Lipids Extracted from Worn Soft Contact Lenses

Science.gov (United States)

Svitova, Tatyana F.; Lin, Meng C.

2014-01-01

Purpose To explore interfacial behaviors and effect of temperature and dilatation on dynamic properties of multilayered human tear lipids extracted from silicone hydrogel (SiH) lenses worn by asymptomatic Asian and Caucasian subjects. Methods Interfacial properties of lipids extracted from Focus® N&D lenses worn by 14 subjects continuously for 1 month were studied. The lipids were deposited on an air bubble immersed in a model tear electrolytes (MTE) solution to form 100 ± 20 nm-thick films. Surface pressure was recorded during slow expansion/contraction cycles to evaluate compressibility and hysteresis of lipid films. Films were also subjected to fast step-strain dilatations at temperatures 22°–45° C for their visco-elastic properties assessment. Results Iso-cycles for Asian and Caucasian lipids were similar at low surface pressures, but had distinctly different compressibility and hysteresis at dynamic pressures exceeding 30 mN/m. Rheological parameters of reconstituted lipids were also dissimilar between Asian and Caucasian. The elastic modulusE∞ for Caucasian lipids was 1.5 times higher than that for Asian lipids, whereas relaxation time (t) was on average 1.3 times higher for Asian. No significant changes were observed in rheological properties of both Asian and Caucasian lipids when temperature increased from 22.0° to 36.5° C. However, for Caucasian lipids, E∞ reduced considerably at temperatures above 42.0° C, while t remained unchanged. For Asian lipids, both E∞ and t started to decline as temperature increased to 38° C and higher. Conclusions Higher elastic modulus of Caucasian lipids and elasticity threshold at certain deformations indicate stronger structure and intermolecular interactions as compared with more viscous Asian lipids. The differences in interfacial behaviors between Asian and Caucasian lipids may be associated with the differences in their chemical compositions. PMID:24270592

Racial variations in interfacial behavior of lipids extracted from worn soft contact lenses.

Science.gov (United States)

Svitova, Tatyana F; Lin, Meng C

2013-12-01

To explore interfacial behaviors and effects of temperature and dilatation on dynamic properties of multilayered human tear lipids extracted from silicone hydrogel (SiH) lenses worn by asymptomatic Asian and white subjects. Interfacial properties of lipids extracted from Focus N&D lenses worn by 14 subjects continuously for 1 month were studied. The lipids were deposited on an air bubble immersed in a model tear electrolyte (MTE) solution to form 100 ± 20-nm-thick films. Surface pressure was recorded during slow expansion/contraction cycles to evaluate compressibility and hysteresis of lipid films. Films were also subjected to fast step-strain dilatations at temperatures of 22 to 45°C for their viscoelastic property assessment. Isocycles for Asian and white lipids were similar at low surface pressures but had distinctly different compressibility and hysteresis at dynamic pressures exceeding 30 mN/m. Rheological parameters of reconstituted lipids were also dissimilar between Asian and white. The elastic modulus E∞ for white lipids was 1.5 times higher than that for Asian lipids, whereas relaxation time (t) was on average 1.3 times higher for Asian. No significant changes were observed in rheological properties of both Asian and white lipids when temperature increased from 22.0 to 36.5°C. However, for white lipids, E∞ reduced considerably at temperatures higher than 42.0°C, whereas t remained unchanged. For Asian lipids, both E∞ and t started to decline as temperature increased to 38°C and higher. Higher elastic modulus of white lipids and elasticity threshold at certain deformations indicate stronger structure and intermolecular interactions as compared with more viscous Asian lipids. The differences in interfacial behaviors between Asian and white lipids may be associated with the differences in their chemical compositions.

Planck 2015 results. XV. Gravitational lensing

CERN Document Server

Ade, P.A.R.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Bartlett, J.G.; Bartolo, N.; Basak, S.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bock, J.J.; Bonaldi, A.; Bonavera, L.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R.C.; Calabrese, E.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chiang, H.C.; Christensen, P.R.; Church, S.; Clements, D.L.; Colombi, S.; Colombo, L.P.L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B.P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; Davis, R.J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Diego, J.M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T.A.; Eriksen, H.K.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A.A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K.M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J.E.; Hansen, F.K.; Hanson, D.; Harrison, D.L.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huffenberger, K.M.; Hurier, G.; Jaffe, A.H.; Jaffe, T.R.; Jones, W.C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T.S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C.R.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Lewis, A.; Liguori, M.; Lilje, P.B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P.M.; Macías-Pérez, J.F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P.G.; Martínez-González, E.; Masi, S.; Matarrese, S.; McGehee, P.; Meinhold, P.R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J.A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C.B.; Nørgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C.A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G.W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J.P.; Reach, W.T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rowan-Robinson, M.; Rubiño-Martín, J.A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M.D.; Shellard, E.P.S.; Spencer, L.D.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J.A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L.A.; Wandelt, B.D.; Wehus, I.K.; White, M.; Yvon, D.; Zacchei, A.

2016-01-01

We present the most significant measurement of the cosmic microwave background (CMB) lensing potential to date (at a level of 40 sigma), using temperature and polarization data from the Planck 2015 full-mission release. Using a polarization-only estimator we detect lensing at a significance of 5 sigma. We cross-check the accuracy of our measurement using the wide frequency coverage and complementarity of the temperature and polarization measurements. Public products based on this measurement include an estimate of the lensing potential over approximately 70% of the sky, an estimate of the lensing potential power spectrum in bandpowers for the multipole range 40lensing potential power spectrum and that found in the best-fitting LCDM model based on the Planck temperature and polarization power spectra. Using the lensing likelihood alone we obtain a percent-level measurement of ...

Gravitational lensing of quasars

CERN Document Server

Eigenbrod, Alexander

2013-01-01

The universe, in all its richness, diversity and complexity, is populated by a myriad of intriguing celestial objects. Among the most exotic of them are gravitationally lensed quasars. A quasar is an extremely bright nucleus of a galaxy, and when such an object is gravitationally lensed, multiple images of the quasar are produced – this phenomenon of cosmic mirage can provide invaluable insights on burning questions, such as the nature of dark matter and dark energy. After presenting the basics of modern cosmology, the book describes active galactic nuclei, the theory of gravitational lensing, and presents a particular numerical technique to improve the resolution of astronomical data. The book then enters the heart of the subject with the description of important applications of gravitational lensing of quasars, such as the measurement of the famous Hubble constant, the determination of the dark matter distribution in galaxies, and the observation of the mysterious inner parts of quasars with much higher r...

Non-Amontons-Coulomb local friction law of randomly rough contact interfaces with rubber

OpenAIRE

Nguyen, D. T.; Wandersman, E.; Prevost, A.; Chenadec, Y. Le; Fretigny, C.; Chateauminois, A.

2017-01-01

We report on measurements of the local friction law at a multi-contact interface formed between a smooth rubber and statistically rough glass lenses, under steady state friction. Using contact imaging, surface displacements are measured, and inverted to extract both distributions of frictional shear stress and contact pressure with a spatial resolution of about 10~$\\mu$m. For a glass surface whose topography is self-affine with a Gaussian height asperity distribution, the local frictional she...

Evaluation of diminished microbial contamination in handling of a novel daily disposable flat pack contact lens.

Science.gov (United States)

Nomachi, Miya; Sakanishi, Kotaro; Ichijima, Hideji; Cavanagh, H Dwight

2013-05-01

To evaluate the efficacy of a novel daily disposable (DD) flat package in regard to microbial contamination on the anterior and posterior surfaces of a contact lens (CL) during handling of the lens for insertion. Four kinds of commercially available general blister-packed daily disposable contact lenses (DD CLs) as controls and a novel Magic 1-day Menicon Flat Pack as a test lens were used for this in vitro study. Lenses were removed from their packages using fingers coated with fluorescein 3 to 5 μm beads or an approximately 7×10(2) to 2×10(3) colony-forming unit (CFU)/mL Staphylococcus aureus suspension. The transfer of fluorescein beads to the surface of the lenses was then observed by fluorescence microscopy. Microbial contamination on the lenses was observed by light microscopy after a 2-day incubation period; and, the number of colonies isolated from the contaminated lenses was determined after 4 days of incubation. The number of fluorescein beads on the Magic lens was significantly less (p<0.05) than that of the general blister-packed control lenses. Adherence of microbial colonies was observed on both inner and outer surfaces of general blister-packed lenses, whereas no colony formation was found on the inner surface of the Magic lens, and the lowest bacterial adherence was observed for the Magic lens. The data demonstrated that placement of the Magic DD lens onto the eye is accompanied by diminished microbial contamination compared with general blister-packed DD CLs. Eye care professionals; however, should instruct patients to comply with intended use of DD CLs to prevent CL-associated microbial keratitis. In all cases, hand washing is mandated prelens insertion.

KINOFORM LENSES - TOWARD NANOMETER RESOLUTION.

Energy Technology Data Exchange (ETDEWEB)

STEIN, A.; EVANS-LUTTERODT, K.; TAYLOR, A.

2004-10-23

While hard x-rays have wavelengths in the nanometer and sub-nanometer range, the ability to focus them is limited by the quality of sources and optics, and not by the wavelength. A few options, including reflective (mirrors), diffractive (zone plates) and refractive (CRL's) are available, each with their own limitations. Here we present our work with kinoform lenses which are refractive lenses with all material causing redundant 2{pi} phase shifts removed to reduce the absorption problems inherently limiting the resolution of refractive lenses. By stacking kinoform lenses together, the effective numerical aperture, and thus the focusing resolution, can be increased. The present status of kinoform lens fabrication and testing at Brookhaven is presented as well as future plans toward achieving nanometer resolution.

Galaxy–Galaxy Weak-lensing Measurements from SDSS. I. Image Processing and Lensing Signals

Energy Technology Data Exchange (ETDEWEB)

Luo, Wentao [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Nandan Road 80, Shanghai 200030 (China); Yang, Xiaohu; Zhang, Jun; Tweed, Dylan [Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Fu, Liping; Shu, Chenggang [Shanghai Key Lab for Astrophysics, Shanghai Normal University, 100 Guilin Road, 200234, Shanghai (China); Mo, H. J. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003-9305 (United States); Bosch, Frank C. van den [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Li, Ran [Key Laboratory for Computational Astrophysics, Partner Group of the Max Planck Institute for Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012 (China); Li, Nan [Department of Astronomy and Astrophysics, The University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Liu, Xiangkun; Pan, Chuzhong [Department of Astronomy, Peking University, Beijing 100871 (China); Wang, Yiran [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801 (United States); Radovich, Mario, E-mail: walt@shao.ac.cn, E-mail: xyang@sjtu.edu.cn [INAF-Osservatorio Astronomico di Napoli, via Moiariello 16, I-80131 Napoli (Italy)

2017-02-10

We present our image processing pipeline that corrects the systematics introduced by the point-spread function (PSF). Using this pipeline, we processed Sloan Digital Sky Survey (SDSS) DR7 imaging data in r band and generated a galaxy catalog containing the shape information. Based on our shape measurements of the galaxy images from SDSS DR7, we extract the galaxy–galaxy (GG) lensing signals around foreground spectroscopic galaxies binned in different luminosities and stellar masses. We estimated the systematics, e.g., selection bias, PSF reconstruction bias, PSF dilution bias, shear responsivity bias, and noise rectification bias, which in total is between −9.1% and 20.8% at 2 σ levels. The overall GG lensing signals we measured are in good agreement with Mandelbaum et al. The reduced χ {sup 2} between the two measurements in different luminosity bins are from 0.43 to 0.83. Larger reduced χ {sup 2} from 0.60 to 1.87 are seen for different stellar mass bins, which is mainly caused by the different stellar mass estimator. The results in this paper with higher signal-to-noise ratio are due to the larger survey area than SDSS DR4, confirming that more luminous/massive galaxies bear stronger GG lensing signals. We divide the foreground galaxies into red/blue and star-forming/quenched subsamples and measure their GG lensing signals. We find that, at a specific stellar mass/luminosity, the red/quenched galaxies have stronger GG lensing signals than their counterparts, especially at large radii. These GG lensing signals can be used to probe the galaxy–halo mass relations and their environmental dependences in the halo occupation or conditional luminosity function framework.

Review on prevention of bacterial adhesion on contact lens using plasma treatment

Science.gov (United States)

Ramli, N. A. H.; Zaaba, S. K.; Mustaffa, M. T.; Zakaria, A.; Shahriman A., B.

2017-03-01

Many researches had been conducted to enhance the properties of contact lens. Most of the research conducted discussed on the factors that affect the adhesion process to contact lenses, rate of contact lens contamination, and type of microbe that adhere on the contact lens surface and contact lens casing. Studies on the proposed strategies or technology that can be used to slower down the formation of bacteria on contact lens are being explored. New technologies or strategies to prevent or slow down the adhesion of bacteria on contact lens have become a priority in this area. This review paper covers two main aspects, namely factor that affect the bacteria adhesion on contact lens and also the introduction of plasma treatment as a potential method for contact lens treatment.

Bilateral Acanthamoeba ulcer in a user of disposable soft contact lenses: a tragic incident or a consequence of the aggressive policy of soft contact lens trading? Úlcera bilateral por Acanthamoeba em usuária de lentes de contato gelatinosas descartáveis: um incidente trágico ou uma conseqüência da política agressiva de venda de lentes de contato gelatinosas?

Directory of Open Access Journals (Sweden)

Sidney Júlio de Faria e Sousa

2008-06-01

Full Text Available This is the report of a case of bilateral Acanthamoeba keratitis in a 19-year-old woman who bought a pair of disposable soft contact lenses in a boutique. She wore this same pair of lenses for 3 months daily without the appropriate care. This led to bilateral corneal transplantation with cataract extraction and also trabeculectomy in the right eye. When last seen, both grafts were crystal clear but the visual acuities were far from satisfactory. She also had bilateral secondary glaucoma, barely controlled by topical medication. Actually, the physical features and the wearing time characteristics of the disposable soft contact lenses created unprecedented difficulties to the medical surveillance of their wearers. Without the right assistance they tend to become careless regarding routine cleaning. They also feel free to buy less expensive lenses, to use saline instead of lens solutions, to violate the limits of wearing time and to extend the use over the sleeping period. Additionally, the aggressive marketing and the wide distribution of these lenses increase the chances that economically or educationally unprepared people will acquire them. The question that remains is: Is the present case an accidental event or an example of what is likely to happen in the future if the indiscriminate selling of disposable soft contact lenses continues to evolve?Este é o relato de uma paciente do sexo feminino, de 19 anos, com ceratite bilateral por Acanthamoeba, devido ao uso de lentes de contato descartáveis, adquiridas em uma butique. Fez uso do mesmo par de lentes durante três meses, sem os cuidados adequados. Foi submetida a transplante penetrante de córnea e facectomia bilateral, além de trabeculectomia no olho direito. Quando vista pela última vez, os enxertos estavam transparentes, mas a visão de ambos os olhos não era satisfatória. Ela também apresentava glaucoma secundário bilateral, controlado precariamente com medicação tópica. Ocorre

One Episode, Two Lenses

Science.gov (United States)

Drijvers, Paul; Godino, Juan D.; Font, Vicenc; Trouche, Luc

2013-01-01

A deep understanding of students' learning processes is one of the core challenges of research in mathematics education. To achieve this, different theoretical lenses are available. The question is how these different lenses compare and contrast, and how they can be coordinated and combined to provide a more comprehensive view on the topic of…

Protein deposition on a lathe-cut silicone hydrogel contact lens material.

Science.gov (United States)

Subbaraman, Lakshman N; Woods, Jill; Teichroeb, Jonathan H; Jones, Lyndon

2009-03-01

To determine the quantity of total protein, total lysozyme, and the conformational state of lysozyme deposited on a novel, lathe-cut silicone hydrogel (SiHy) contact lens material (sifilcon A) after 3 months of wear. Twenty-four subjects completed a prospective, bilateral, daily-wear, 9-month clinical evaluation in which the subjects were fitted with a novel, custom-made, lathe-cut SiHy lens material. The lenses were worn for three consecutive 3-month periods, with lenses being replaced after each period of wear. After 3 months of wear, the lenses from the left eye were collected and assessed for protein analysis. The total protein deposited on the lenses was determined by a modified Bradford assay, total lysozyme using Western blotting and the lysozyme activity was determined using a modified micrococcal assay. The total protein recovered from the custom-made lenses was 5.3 +/- 2.3 microg/lens and the total lysozyme was 2.4 +/- 1.2 microg/lens. The denatured lysozyme found on the lenses was 1.9 +/- 1.0 microg/lens and the percentage of lysozyme denatured was 80 +/- 10%. Even after 3 months of wear, the quantity of protein and the conformational state of lysozyme deposited on these novel lens materials was very similar to that found on similar surface-coated SiHy lenses after 2 to 4 weeks of wear. These results indicate that extended use of the sifilcon A material is not deleterious in terms of the quantity and quality of protein deposited on the lens.

Dry Eye Treatment Based on Contact Lens Drug Delivery: A Review.

Science.gov (United States)

Guzman-Aranguez, Ana; Fonseca, Begoña; Carracedo, Gonzalo; Martin-Gil, Alba; Martinez-Aguila, Alejandro; Pintor, Jesús

2016-09-01

Dry eye disease affects a substantial segment of the word population with increasing frequency. It is a multifactorial disease of the ocular surface and tear film, which causes ocular discomfort, visual disturbances, and tear instability with potential damage to the cornea and conjunctiva. Because of its multifactorial etiology, the use of different pharmacological treatment for dry eye treatment has been proposed, which include anti-inflammatory molecules, lubricants or comfort agents, and secretagogues. However, in some cases these pharmacological approaches only relieve symptoms temporarily, and consequently, eye care professionals continue to have difficulties managing dry eye. To improve pharmacological therapy that allows a more efficient and long-term action, effective ocular drug delivery of the currently available drugs for dry eye treatment is required. Contact lenses are emerging as alternative ophthalmic drugs delivery systems that provide an increased residence time of the drug at the eye, thus leading to enhanced bioavailability and more convenient and efficacious therapy. In this article, we reviewed the different techniques used to prepare contact lens-based drug delivery systems and focused on articles that describe the delivery of compounds for dry eye treatment through contact lenses.

Weak lensing of the Lyman α forest

Science.gov (United States)

Croft, Rupert A. C.; Romeo, Alessandro; Metcalf, R. Benton

2018-06-01

The angular positions of quasars are deflected by the gravitational lensing effect of foreground matter. The Lyman α (Lyα) forest seen in the spectra of these quasars is therefore also lensed. We propose that the signature of weak gravitational lensing of the Lyα forest could be measured using similar techniques that have been applied to the lensed cosmic microwave background (CMB), and which have also been proposed for application to spectral data from 21-cm radio telescopes. As with 21-cm data, the forest has the advantage of spectral information, potentially yielding many lensed `slices' at different redshifts. We perform an illustrative idealized test, generating a high-resolution angular grid of quasars (of order arcminute separation), and lensing the Lyα forest spectra at redshifts z = 2-3 using a foreground density field. We find that standard quadratic estimators can be used to reconstruct images of the foreground mass distribution at z ˜ 1. There currently exists a wealth of Lyα forest data from quasar and galaxy spectral surveys, with smaller sightline separations expected in the future. Lyα forest lensing is sensitive to the foreground mass distribution at redshifts intermediate between CMB lensing and galaxy shear, and avoids the difficulties of shape measurement associated with the latter. With further refinement and application of mass reconstruction techniques, weak gravitational lensing of the high-redshift Lyα forest may become a useful new cosmological probe.

Achromatic X-ray lenses

International Nuclear Information System (INIS)

Umbach, Marion

2009-01-01

This thesis presents first results on the development of achromatic refractive X-ray lenses which can be used for scientific experiments at synchrotron sources. First of all the different requirements for achromatic X-ray lenses have been worked out. There are different types of lenses, one type can be used for monochromatized sources when the energy is scanned while the spot size should be constant. The other type can be used at beamlines providing a broad energy band. By a combination of focusing and defocusing elements we have developed a lens system that strongly reduces the chromatic aberration of a refractive lens in a given energy range. The great challenge in the X-ray case - in contrast to the visible range - the complex refractive index, which is very similar for the possible materials in the X-ray spectrum. For precise studies a numerical code has been developed, which calculates the different rays on their way through the lenses to the detector plane via raytracing. In this numerical code the intensity distribution in the detector plane has been analyzed for a chromatic and the corresponding achromatic system. By optimization routines for the two different fields of applications specific parameter combinations were found. For the experimental verification an achromatic system has been developed, consisting of biconcave SU-8 lenses and biconvex Nickel Fresnel lenses. Their fabrication was based on the LIGA-process, including a further innovative development, namely the fabrication of two different materials on one wafer. In the experiment at the synchrotron source ANKA the energy was varied in a specific energy range in steps of 0.1 keV. The intensity distribution for the different energies was detected at a certain focal length. For the achromatic system a reduction of the chromatic aberration could be clearly shown. Achromatic refractive X-ray lenses, especially for the use at synchrotron sources, have not been developed so far. As a consequence of the

Exchange of tears under a contact lens is driven by distortions of the contact lens.

Science.gov (United States)

Maki, Kara L; Ross, David S

2014-12-01

We studied the flow of the post-lens tear film under a soft contact lens to understand how the design parameters of contact lenses can affect ocular health. When a soft contact lens is inserted, the blinking eyelid causes the lens to stretch in order to conform to the shape of the eye. The deformed contact lens acts to assume its un-deformed shape and thus generates a suction pressure in the post-lens tear film. In consequence, the post-lens tear fluid moves; it responds to the suction pressure. The suction pressure may draw in fresh fluid from the edge of the lens, or it may eject fluid there, as the lens reassumes its un-deformed shape. In this article, we develop a mathematical model of the flow of the post-lens tear fluid in response to the mechanical suction pressure of a deformed contact lens. We predict the amount of exchange of fluid exchange under a contact lens and we explore the influence of the eye's shape on the rate of exchange of fluid. © The Author 2014. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Soft, smart contact lenses with integrations of wireless circuits, glucose sensors, and displays.

Science.gov (United States)

Park, Jihun; Kim, Joohee; Kim, So-Yun; Cheong, Woon Hyung; Jang, Jiuk; Park, Young-Geun; Na, Kyungmin; Kim, Yun-Tae; Heo, Jun Hyuk; Lee, Chang Young; Lee, Jung Heon; Bien, Franklin; Park, Jang-Ung

2018-01-01

Recent advances in wearable electronics combined with wireless communications are essential to the realization of medical applications through health monitoring technologies. For example, a smart contact lens, which is capable of monitoring the physiological information of the eye and tear fluid, could provide real-time, noninvasive medical diagnostics. However, previous reports concerning the smart contact lens have indicated that opaque and brittle components have been used to enable the operation of the electronic device, and this could block the user's vision and potentially damage the eye. In addition, the use of expensive and bulky equipment to measure signals from the contact lens sensors could interfere with the user's external activities. Thus, we report an unconventional approach for the fabrication of a soft, smart contact lens in which glucose sensors, wireless power transfer circuits, and display pixels to visualize sensing signals in real time are fully integrated using transparent and stretchable nanostructures. The integration of this display into the smart lens eliminates the need for additional, bulky measurement equipment. This soft, smart contact lens can be transparent, providing a clear view by matching the refractive indices of its locally patterned areas. The resulting soft, smart contact lens provides real-time, wireless operation, and there are in vivo tests to monitor the glucose concentration in tears (suitable for determining the fasting glucose level in the tears of diabetic patients) and, simultaneously, to provide sensing results through the contact lens display.

Extended depth of focus contact lenses vs. two commercial multifocals: Part 1. Optical performance evaluation via computed through-focus retinal image quality metrics.

Science.gov (United States)

Bakaraju, Ravi C; Ehrmann, Klaus; Ho, Arthur

To compare the computed optical performance of prototype lenses designed using deliberate manipulation of higher-order spherical aberrations to extend depth-of-focus (EDOF) with two commercial multifocals. Emmetropic, presbyopic, schematic eyes were coupled with prototype EDOF and commercial multifocal lenses (Acuvue Oasys for presbyopia, AOP, Johnson & Johnson & Air Optix Aqua multifocal, AOMF, Alcon). For each test configuration, the through-focus retinal image quality (TFRIQ) values were computed over 21 vergences, ranging from -0.50 to 2.00D, in 0.125D steps. Analysis was performed considering eyes with three different inherent aberration profiles: five different pupils and five different lens decentration levels. Except the LOW design, the AOP lenses offered 'bifocal' like TFRIQ performance. Lens performance was relatively independent to pupil and aberrations but not centration. Contrastingly, AOMF demonstrated distance centric performance, most dominant in LOW followed by MED and HIGH designs. AOMF lenses were the most sensitive to pupil, aberrations and centration. The prototypes demonstrated a 'lift-off' in the TFRIQ performance, particularly at intermediate and near, without trading performance at distance. When compared with AOP and AOMF, EDOF lenses demonstrated reduced sensitivity to pupil, aberrations and centration. With the through focus retinal image quality as the gauge of optical performance, we demonstrated that the prototype EDOF designs were less susceptible to variations in pupil, inherent ocular aberrations and decentration, compared to the commercial designs. To ascertain whether these incremental improvements translate to a clinically palpable outcome requires investigation through human trials. Copyright © 2017 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

The Impact of Inoculation Parameters on the Pathogenesis of Contact Lens–Related Infectious Keratitis

Science.gov (United States)

Tam, Connie; Mun, James J.; Evans, David J.

2010-01-01

Purpose. Contact lens wear predisposes to Pseudomonas aeruginosa keratitis, but the mechanisms involved remain unclear. An in vivo model was used to study lens inoculation conditions enabling disease. Methods. Custom-made hydrogel contact lenses were fitted to rats after incubation in P. aeruginosa approximately 1011 cfu/mL (3 hours) or approximately 103 cfu/mL (24 hours). Another group was inadvertently inoculated with a suction pen previously used with high inocula, but rinsed in ethanol and stored dry (6 months). Some corneas were tissue paper–blotted to cause fluorescein staining before lens fitting. Contralateral eyes were untreated. Twenty-four hours after disease detection, lenses were transferred to naive rats or examined by confocal microscopy before homogenization to quantify viable bacteria. After lens removal, corneas were washed to collect nonadherent bacteria and were analyzed by immunohistochemistry. Results. All eyes challenged with unworn contaminated lenses developed keratitis after approximately 7 to 10 days. Disease delay and severity were unaffected by inoculum parameters or tissue blotting but occurred sooner with lenses transferred from infected eyes (∼2 days). Worn lenses and corneal washes contained infecting bacteria. Posterior, not anterior, lens surfaces harbored P. aeruginosa biofilms that penetrated the lens matrix. Diseased corneas showed an infiltration of phagocytes and T-lymphocytes. Conclusions. P. aeruginosa induces keratitis in this lens-wearing model after a single inoculation. Delayed disease onset was interesting considering the greater keratitis risk during extended wear. Infection did not require the disruption of corneal barrier function before lens wear and occurred without exposure to lens care solutions. The data suggest that keratitis involves biofilm formation or other bacterial adaptations in vivo. PMID:20130275

Diquafosol Ophthalmic Solution Increases Pre- and Postlens Tear Film During Contact Lens Wear in Rabbit Eyes.

Science.gov (United States)

Nagahara, Yukiko; Koh, Shizuka; Oshita, Yoshihiro; Nagano, Takashi; Mano, Hidetoshi; Nishida, Kohji; Watanabe, Hitoshi

2017-11-01

To investigate the behavior of prelens tear film (PLTF) and postlens tear film (PoLTF) after the instillation of diquafosol using an experimental rabbit model of eyes with contact lens. Cross-sectional, anterior segment optical coherence tomographic images of the inferior midperipheral cornea were obtained at baseline and at 5, 15, 30, 60, 90, and 120 min after the instillation of 3% diquafosol ophthalmic solution in 10 Japanese white rabbits wearing contact lenses. From the obtained images, the areas of the PLTF and PoLTF were calculated. Both artificial tear solution and 0.1% sodium hyaluronate ophthalmic solution were used for comparison. Significant fluid accumulation in both the PLTF and PoLTF was observed after diquafosol instillation, whereas no fluid accumulation was visible after the instillation of artificial tear or sodium hyaluronate. The increase in PLTF area after diquafosol instillation was significantly higher (Pophthalmic solution increases PLTF and PoLTF in rabbit eyes with contact lenses. Diquafosol has potential as a treatment option for contact lens-related dry eye.

Therapeutic use of mini-scleral lenses in a patient with Graves' ophthalmopathy.

Science.gov (United States)

Harthan, Jennifer S

2014-01-01

Patients with Graves' ophthalmopathy can be very challenging to manage secondary to the complex nature of their disease presentation. Patients may present with a variety of ocular findings including: lid retraction, periorbital and lid swelling, chemosis, conjunctival hyperemia, proptosis, optic neuropathy, restrictive myopathy, exposure keratopathy and/or keratoconjunctivitis sicca. Mini-scleral and scleral lens designs have been important in the management of irregular and regular corneas, and in the therapy of ocular surface diseases. We present here the case of a 48-year-old Caucasian male who had been diagnosed with Graves' ophthalmopathy 13 years earlier. With significant ocular surface staining and over ten diopters of astigmatism, the patient had never been able to wear contact lenses comfortably. After being fit with the Mini-Scleral Design™ lenses, his vision improved to 20/25 OU, his ocular surface improved, and overall quality of vision increased. Copyright © 2012 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Contact lens surface by electron beam

International Nuclear Information System (INIS)

Shin, Jung Hyuck; Lee, Suk Ju; Hwang, Kwang Ha; Jeon Jin

2011-01-01

Contact lens materials needs good biocompatibility, high refractive index, high optical transparency, high water content etc. Surface treat method by using plasma and radiation can modify the physical and/or chemical properties of the contact lens surface. Radiation technology such as electron beam irradiation can apply to polymerization reaction and enhance the functionality of the polymer.The purpose of this study is to modify of contact lens surface by using Eb irradiation technology. Electron beam was irradiated to the contact lens surface which was synthesized thermal polymerization method and commercial contact lens to modify physical and chemical properties. Ft-IR, XP, UV-vis spectrophotometer, water content, oxygen trans-metastability were used to characterize the surface state, physicochemical, and optical property of the contact lens treated with Eb. The water content and oxygen transmissibility of the contact lens treated with Eb were increased due to increase in the hydrophilic group such as O-C=O and OH group on the contact lens surface which could be produced by possible reaction between carbon and oxygen during the Eb irradiation. All of the lenses showed the high optical transmittance above 90%. In this case of B/Es, TES, Ti contact lens, the optical transmittance decreased about 5% with increasing Eb dose in the wavelength of UV-B region. The contact lens modified by Eb irradiation could improve the physical properties of the contact lens such as water content and oxygen transmissibility

How to prevent and treat anysometropic-amblyopic child by contact lenses.

Science.gov (United States)

Salopek-Rabatić, Jasminka; Pavan, Josip; Kastelan, Snjezana; Rabatić, Leon

2013-04-01

Anisometropy as a first step on a way forward future amblyopic child, can be prevent and treat if this condition is recognased on time. Second step is wisdom, right contact lens fit on bothes eyes. As follow, some ortoptic-pleoptic procedures depending on (objective, subjective squinting angle, state of fusion, visus on bothes eyes and separatly each eay and condition of nervus opticus (VEP), normal or absent retinal corespondence, are recomended. There is no limit how old a child is, but best choice and best compliance is age between five and twelve. Contact lens materiales, different fit procedures, right diagnosys and tips all about are discussed.

EDITORIAL: Focus on Gravitational Lensing

Science.gov (United States)

Jain, Bhuvnesh

2007-11-01

Gravitational lensing emerged as an observational field following the 1979 discovery of a doubly imaged quasar lensed by a foreground galaxy. In the 1980s and '90s dozens of other multiply imaged systems were observed, as well as time delay measurements, weak and strong lensing by galaxies and galaxy clusters, and the discovery of microlensing in our galaxy. The rapid pace of advances has continued into the new century. Lensing is currently one of best techniques for finding and mapping dark matter over a wide range of scales, and also addresses broader cosmological questions such as understanding the nature of dark energy. This focus issue of New Journal of Physics presents a snapshot of current research in some of the exciting areas of lensing. It provides an occasion to look back at the advances of the last decade and ahead to the potential of the coming years. Just about a decade ago, microlensing was discovered through the magnification of stars in our galaxy by invisible objects with masses between that of Jupiter and a tenth the mass of the Sun. Thus a new component of the mass of our galaxy, dubbed MACHOs, was established (though a diffuse, cold dark matter-like component is still needed to make up most of the galaxy mass). More recently, microlensing led to another exciting discovery—of extra-solar planets with masses ranging from about five times that of Earth to that of Neptune. We can expect many more planets to be discovered through ongoing surveys. Microlensing is the best technique for finding Earth mass planets, though it is not as productive overall as other methods and does not allow for follow up observations. Beyond planet hunting, microlensing has enabled us to observe previously inaccessible systems, ranging from the surfaces of other stars to the accretion disks around the black holes powering distant quasars. Galaxies and galaxy clusters at cosmological distances can produce dramatic lensing effects: multiple images of background galaxies

Gauge-invariant formalism of cosmological weak lensing

Science.gov (United States)

Yoo, Jaiyul; Grimm, Nastassia; Mitsou, Ermis; Amara, Adam; Refregier, Alexandre

2018-04-01

We present the gauge-invariant formalism of cosmological weak lensing, accounting for all the relativistic effects due to the scalar, vector, and tensor perturbations at the linear order. While the light propagation is fully described by the geodesic equation, the relation of the photon wavevector to the physical quantities requires the specification of the frames, where they are defined. By constructing the local tetrad bases at the observer and the source positions, we clarify the relation of the weak lensing observables such as the convergence, the shear, and the rotation to the physical size and shape defined in the source rest-frame and the observed angle and redshift measured in the observer rest-frame. Compared to the standard lensing formalism, additional relativistic effects contribute to all the lensing observables. We explicitly verify the gauge-invariance of the lensing observables and compare our results to previous work. In particular, we demonstrate that even in the presence of the vector and tensor perturbations, the physical rotation of the lensing observables vanishes at the linear order, while the tetrad basis rotates along the light propagation compared to a FRW coordinate. Though the latter is often used as a probe of primordial gravitational waves, the rotation of the tetrad basis is indeed not a physical observable. We further clarify its relation to the E-B decomposition in weak lensing. Our formalism provides a transparent and comprehensive perspective of cosmological weak lensing.

[Scheimpflug photography for the examination of phakic intraocular lenses].

Science.gov (United States)

Baumeister, M

2014-10-01

High myopia phakic intraocular lenses (IOL) have become an established means of surgical correction for high ametropia. Scheimpflug photography is one of the methods which are frequently applied for postoperative examination of the implants. Results from published studies employing Scheimpflug photography for examination of anterior chamber angle-fixated, iris-fixated and sulcus-fixated phakic IOLs were evaluated. In several published studies Scheimpflug photography was used to examine the position of the implant and opacification of the crystalline lens. The results provided valuable evidence for the improvement of phakic IOL design. Scheimpflug photography offers an easy to use, rapid non-contact examination of phakic IOLs.

Weak lensing and dark energy

International Nuclear Information System (INIS)

Huterer, Dragan

2002-01-01

We study the power of upcoming weak lensing surveys to probe dark energy. Dark energy modifies the distance-redshift relation as well as the matter power spectrum, both of which affect the weak lensing convergence power spectrum. Some dark-energy models predict additional clustering on very large scales, but this probably cannot be detected by weak lensing alone due to cosmic variance. With reasonable prior information on other cosmological parameters, we find that a survey covering 1000 sq deg down to a limiting magnitude of R=27 can impose constraints comparable to those expected from upcoming type Ia supernova and number-count surveys. This result, however, is contingent on the control of both observational and theoretical systematics. Concentrating on the latter, we find that the nonlinear power spectrum of matter perturbations and the redshift distribution of source galaxies both need to be determined accurately in order for weak lensing to achieve its full potential. Finally, we discuss the sensitivity of the three-point statistics to dark energy

Contact lens wear by Royal Air Force aircrew in World War II.

Science.gov (United States)

Pearson, Richard M

2014-04-01

To provide an overview of the use of contact lenses by RAF aircrew in World War II by identifying some of the fitters and wearers and appraising the clinical results that they achieved. A wide-ranging literature search was undertaken that encompassed peer-reviewed journals, non-refereed publications, books, official publications, newspapers and archived documents. Thirty-one aircrew are known to have worn sealed scleral lenses in order to meet the required visual standards. Of these, only two were considered to be completely unsuccessful, one of whom was unilaterally aphakic. One additional case of undisclosed contact lens wear was found and the identity of this officer was established. Brief biographies of a few pilots establish the context of their contact lens wear. Overall, the results of scleral lens wear were variable reflecting those achieved by civilian patients of the period. While three men complained of discomfort due to heat and glare, one pilot experienced no photophobia when flying above white clouds in brilliant sunshine and another found no difficulty caused by altitude or tropical climate. Wearing time ranged from about 2h to 16, or more, hours. In about a third of the cases, wearing time was limited due to the onset of a form of contact lens induced-epithelial oedema known as Sattler's veil and effective solutions to this problem were not implemented until after the war. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Investigations of Galaxy Clusters Using Gravitational Lensing

Energy Technology Data Exchange (ETDEWEB)

Wiesner, Matthew P. [Northern Illinois Univ., DeKalb, IL (United States)

2014-08-01

In this dissertation, we discuss the properties of galaxy clusters that have been determined using strong and weak gravitational lensing. A galaxy cluster is a collection of galaxies that are bound together by the force of gravity, while gravitational lensing is the bending of light by gravity. Strong lensing is the formation of arcs or rings of light surrounding clusters and weak lensing is a change in the apparent shapes of many galaxies. In this work we examine the properties of several samples of galaxy clusters using gravitational lensing. In Chapter 1 we introduce astrophysical theory of galaxy clusters and gravitational lensing. In Chapter 2 we examine evidence from our data that galaxy clusters are more concentrated than cosmology would predict. In Chapter 3 we investigate whether our assumptions about the number of galaxies in our clusters was valid by examining new data. In Chapter 4 we describe a determination of a relationship between mass and number of galaxies in a cluster at higher redshift than has been found before. In Chapter 5 we describe a model of the mass distribution in one of the ten lensing systems discovered by our group at Fermilab. Finally in Chapter 6 we summarize our conclusions.

Forensic Analysis of a Contact Lens in a Murder Case.

Science.gov (United States)

Zwerling, Charles S

2016-03-01

Contact lenses have had rare relevance in trials and/or investigations. After 5 years of burial, orbital remnants were retrieved from an exhumed body and subsequently identified as a key piece of material evidence in a murder trial. The exhumed case materials were evaluated under laboratory conditions and were determined to be contact lens remnants. Contact lens fracture and burial simulation studies were performed to provide additional corroboration of the physical findings of the exhumed contact lens remnants. This material evidence was instrumental in providing factual proof refuting the defendant's testimony in the murder trial. A brief history of contact lens composition and use is provided for understanding the methods and observational results. This forensic case study represents the first published documentation of a contact lens from an exhumed body being used in a murder investigation and establishes an operational procedure for future forensic contact lens examinations. © 2016 American Academy of Forensic Sciences.

Instrumental systematics and weak gravitational lensing

International Nuclear Information System (INIS)

Mandelbaum, R.

2015-01-01

We present a pedagogical review of the weak gravitational lensing measurement process and its connection to major scientific questions such as dark matter and dark energy. Then we describe common ways of parametrizing systematic errors and understanding how they affect weak lensing measurements. Finally, we discuss several instrumental systematics and how they fit into this context, and conclude with some future perspective on how progress can be made in understanding the impact of instrumental systematics on weak lensing measurements

Multifocal versus monofocal intraocular lenses after cataract extraction

Directory of Open Access Journals (Sweden)

Daniel Calladine

Full Text Available BACKGROUND: Good unaided distance visual acuity is now a realistic expectation following cataract surgery and intraocular lens (IOL implantation. Near vision, however, still requires additional refractive power, usually in the form of reading glasses. Multiple optic (multifocal IOLs are available which claim to allow good vision at a range of distances. It is unclear whether this benefit outweighs the optical compromises inherent in multifocal IOLs. OBJECTIVES: The objective of this review was to assess the effects of multifocal IOLs, including effects on visual acuity, subjective visual satisfaction, spectacle dependence, glare and contrast sensitivity, compared to standard monofocal lenses in people undergoing cataract surgery. METHODS: Search methods: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register, The Cochrane Library 2012, Issue 2, MEDLINE (January 1946 to March 2012, EMBASE (January 1980 to March 2012, the metaRegister of Controlled Trials (mRCT (www.controlled-trials.com, ClinicalTrials.gov (www.clinicaltrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP (www.who.int/ictrp/search/en. We did not use any date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 6 March 2012. We searched the reference lists of relevant articles and contacted investigators of included studies and manufacturers of multifocal IOLs for information about additional published and unpublished studies. Selection criteria: All randomised controlled trials comparing a multifocal IOL of any type with a monofocal IOL as control were included. Both unilateral and bilateral implantation trials were included. Data collection and analysis: Two authors collected data and assessed trial quality. Where possible, we pooled data from the individual studies using a random-effects model, otherwise we tabulated data. MAIN RESULTS: Sixteen completed trials

Weakly oval electron lense

International Nuclear Information System (INIS)

Daumenov, T.D.; Alizarovskaya, I.M.; Khizirova, M.A.

2001-01-01

The method of the weakly oval electrical field getting generated by the axially-symmetrical field is shown. Such system may be designed with help of the cylindric form coaxial electrodes with the built-in quadrupole duplet. The singularity of the indicated weakly oval lense consists of that it provides the conducting both mechanical and electronic adjustment. Such lense can be useful for elimination of the near-axis astigmatism in the electron-optical system

Lenses matching of compound eye for target positioning

Science.gov (United States)

Guo, Fang; Zheng, Yan Pei; Wang, Keyi

2012-10-01

Compound eye, as a new imaging method with multi-lens for a large field of view, could complete target positioning and detection fastly, especially at close range. Therefore it could be applicated in the fields of military and medical treatment and aviation with vast market potential and development prospect. Yet the compound eye imaging method designed use three layer construction of multiple lens array arranged in a curved surface and refractive lens and imaging sensor of CMOS. In order to simplify process structure and increase the imaging area of every sub-eye, the imaging area of every eye is coved with the whole CMOS. Therefore, for several imaging point of one target, the corresponding lens of every imaging point is unkonown, and thus to identify. So an algorithm was put forward. Firstly, according to the Regular Geometry relationship of several adjacent lenses, data organization of seven lenses with a main lens was built. Subsequently, by the data organization, when one target was caught by several unknown lenses, we search every combined type of the received lenses. And for every combined type, two lenses were selected to combine and were used to calculate one three-dimensional (3D) coordinate of the target. If the 3D coordinates are same to the some combine type of the lenses numbers, in theory, the lenses and the imaging points are matched. So according to error of the 3D coordinates is calculated by the different seven lenses numbers combines, the unknown lenses could be distinguished. The experimental results show that the presented algorithm is feasible and can complete matching task for imaging points and corresponding lenses.

High-speed optical signal processing using time lenses

DEFF Research Database (Denmark)

Galili, Michael; Hu, Hao; Guan, Pengyu

2015-01-01

This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle.......This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle....

Dynamics of Fermat potentials in nonperturbative gravitational lensing

International Nuclear Information System (INIS)

Frittelli, Simonetta; Newman, Ezra T.

2002-01-01

We present a framework, based on the null-surface formulation of general relativity, for discussing the dynamics of Fermat potentials for gravitational lensing in a generic situation without approximations of any kind. Additionally, we derive two lens equations: one for the case of thick compact lenses and the other one for lensing by gravitational waves. These equations in principle generalize the astrophysical scheme for lensing by removing the thin-lens approximation while retaining the weak fields

Nanofocusing Parabolic Refractive X-Ray Lenses

International Nuclear Information System (INIS)

Schroer, C.G.; Kuhlmann, M.; Hunger, U.T.; Guenzler, T.F.; Kurapova, O.; Feste, S.; Lengeler, B.; Drakopoulos, M.; Somogyi, A.; Simionovici, A. S.; Snigirev, A.; Snigireva, I.

2004-01-01

Parabolic refractive x-ray lenses with short focal distance can generate intensive hard x-ray microbeams with lateral extensions in the 100nm range even at short distance from a synchrotron radiation source. We have fabricated planar parabolic lenses made of silicon that have a focal distance in the range of a few millimeters at hard x-ray energies. In a crossed geometry, two lenses were used to generate a microbeam with a lateral size of 330nm by 110nm at 25keV in a distance of 41.8m from the synchrotron radiation source. First microdiffraction and fluorescence microtomography experiments were carried out with these lenses. Using diamond as lens material, microbeams with lateral size down to 20nm and below are conceivable in the energy range from 10 to 100keV

Thermal characterization of radiation processed contact lens material

International Nuclear Information System (INIS)

Varshney, L.; Choughule, S.V.

1998-01-01

Differential scanning calorimetry (DSC), thermomechanical analysis (TMA) and thermogravimetry analysis (TGA) were used to characterize radiation processed contact lens gel material of 2-hydroxy ethyl methacrylate(HEMA). DSC revealed two types of water in the gels. DSC and TGA in combination were used to quantitate the percentage of different types of the water in the gel material. Temperature expansion coefficients values indicate more dimensions stability in the radiation processed lenses of similar water contents. (author)