Contact Lens & Anterior Eye - Articles in Press

Onset time course of solution induced corneal staining - Corrected Proof

2010-03-16

Abstract: Purpose: To evaluate the early phase time course of solution induced corneal staining.Methods and materials: A double masked, single centred, prospective clinical trial was conducted. Twenty-five participants, either experienced or new contact lens wearers, participated in the study. Corneal staining response to short term use of ReNu MultiPlus® Multipurpose Solution and PureVision™ silicon hydrogel contact lens with fluorescein was observed using standard techniques after 15, 30, 45, 60 and 120min of lens wear and graded according to the IER scale. Measurements were carried out on separate days for each time point, in random order.Results: Mean extent of staining was greater in test than in control eyes at all time points except baseline. In test eyes, the degree of staining increased successively at each time point after insertion, up to, but not beyond, 60min. For those participants presenting with staining, maximum severity and frequency were both observed at 60min and were significantly greater (p<0.05) than at 15, 30, and 45min.Conclusion: Solution induced corneal staining gradually increased after lens insertion to a maximum at 1h. This level was maintained until at least 2h post-insertion.

Multifocal contact lenses and posterior pole imaging - Corrected Proof

2010-03-16

Multifocal intraocular implants are becoming increasingly popular as a means of correcting presbyopia for pseudophakes. The designs of such lenses may reduce contrast sensitivity and produce visual disturbances such as haloes and glare, particularly under low light conditions such as night driving. What is less known is the effect of these lenses on intraocular imaging; imaging techniques of the retina involve focussing through the entrance pupil and any visual effects caused by the anterior segment could have a consequence on the quality of the image produced.

Progressive cone dystrophy, nystagmus and contact lenses - Corrected Proof

Graeme Stevenson, Lauren Gardner — 2010-03-16

Abstract: Purpose: To describe the contact lens fitting of a 13-year-old girl who suffers from progressive cone dystrophy with associated nystagmus and achromatopsia and a high hyperopic-astigmatic prescription.Methods: The patient was fitted initially with partial correction contact lenses followed by lenses to the full correction some months later.Results: A successful fitting of contact lenses which achieved a standard of vision favourable to that of spectacles, using small diameter soft toric lenses.Conclusion: An improvement in vision has been achieved in this complex case by using specialist small diameter soft toric contact lenses. Not only has an improvement in vision been achieved an improvement in quality of life has also been expressed by the patient and her family.

Practitioners’ analysis of contact lens practice in Hong Kong - Corrected Proof

Jessie Charm, Sin Wan Cheung, Pauline Cho — 2010-03-15

Abstract: Background: The aims of this survey were to appraise contact lens practice and care systems used in Hong Kong between March 2007 and February 2008, and to evaluate the attitude of practitioners towards prescribing different types of contact lenses.Methods: Questionnaires were sent out to 797 optometrists licensed to fit contact lenses in Hong Kong in March 2008.Results: The response rate was 27%. About 20% of contact lens patients (as reported by the respondents) were new wearers. Over 90% of contact lens patients were wearing soft contact lenses. Among soft contact lenses, the use of daily disposable and silicone hydrogel lenses had increased from 27% and 3% in 2002 to 37% and 21% in 2008, respectively. Less than 10% were rigid contact lens wearers. For astigmats fitted with soft lenses, only about 46% were fitted with toric lenses. For presbyopes using contact lenses, the majority (57%) were fitted with single vision lenses with over-spectacles, followed by monovision (29%). The most commonly recommended soft lens disinfecting system was multipurpose solution (74%). Less than 20% of the respondents reported confidence in prescribing orthokeratology lenses.Conclusion: Soft contact lenses continued to dominate the contact lens market in Hong Kong, with silicone hydrogel and daily disposable lenses becoming increasingly popular. The use of toric and bifocal lenses was still not popular among practitioners. Multipurpose solutions were still the care systems of choice by practitioners in Hong Kong.

Contact lens user profile, attitudes and level of compliance to lens care - Corrected Proof

Yvonne Wu, Nicole Carnt, Fiona Stapleton — 2010-03-15

Abstract: Purpose: To identify the demographics profile of lens wearers, and to evaluate the scope and level of noncompliant, behaviours in lens wearers.Methods: 210 contact lens wearers who attended an optometry clinic at an education and research institute, were surveyed using a self-administered questionnaire. The questionnaire was constructed to gather information regarding contact lens wearer demographics, contact lens hygiene behaviours and, attitudes toward lens care. Multivariate testing between lens wearers’ demographic, hygiene, behaviours and attitude to aftercare visit were analysed.Results: One hundred and eleven (62%) of participants responded, with a mean age of 33.8±12 years. 55% of the respondents were female. Major non-compliance aspects identified were poor hand hygiene (11%), inadequate cleaning of lenses (13%) and lens storage cases (61%), and wearers not remembering how often they were advised to return for an aftercare (50%). Lens wearers who purchased contact lenses, from the internet were 3.8 times more likely to forget their aftercare schedule than those who purchased contact lenses from the optometrists (95% CI=1.2–12.2, p=0.024).Conclusion: Poor hand hygiene, inadequate lens care, and not remembering when to come back for aftercares are the common non-compliant behaviours in lens wearers. Purchase of lenses via the internet was associated with lack of awareness of aftercare visit.

Metallic intraocular foreign body retained for four years—An unusual presentation - Corrected Proof

Usha K. Raina, Vinod Kumar, Vasu Kumar, Rouli Sud, Neha Goel, Basudeb Ghosh — 2010-03-11

Abstract: Intraocular foreign bodies present a great threat to both sight and the globe of the patient especially if they are metallic and of long duration. We report a case of a metallic intraocular foreign body that presented four years after the initial trauma. The case was successfully managed by a simple technique and the role of ultrasound biomicroscopy (UBM) is highlighted.

Clinical performance of different care systems with silicone hydrogel contact lenses - Corrected Proof

Nancy Keir, Craig A. Woods, Kathryn Dumbleton, Lyndon Jones — 2010-03-04

Abstract: Purpose: To assess the clinical and subjective performance of a one-step hydrogen peroxide (H2O2) lens care system compared to a multi-purpose disinfecting system (MPDS) when used with silicone hydrogel (SiH) lenses.Methods: This was an eight-week, contralateral (lens type) clinical trial with a randomized, cross-over (care system) design. The H2O2 system was Clear Care ((AO Sept Plus) CIBA VISION) and the MPDS was OPTI-FREE RepleniSH (Alcon) and the SiH materials were lotrafilcon B (Air Optix; CIBA VISION) and senofilcon A (Acuvue OASYS, Johnson & Johnson Vision Care). Investigators and subjects were masked to lens care and lens type, respectively. Clinical variables and ocular health assessments were conducted at a baseline, two-week and four-week visit for each cross-over phase. Comfort, dryness and vision were rated on 0–100 scales. Wearing times and comfortable wearing times were also recorded.Results: Twenty-six subjects were enrolled: nine male, 17 female, mean age (±standard deviation) 31±12 years (range 17–59 years) and 24 subjects completed the study. Clinical variables showed no difference between solutions (all p>0.05), however one subject exhibited solution-induced corneal staining with both lens materials and the MPDS. There was no difference between solutions in subjective overall ratings of comfort, dryness or vision (p>0.05). The H2O2 resulted in longer reported comfortable wearing times than the MPDS (10.93±1.71 vs 9.84±1.47h; repeated measures ANOVA, p<0.01).Conclusions: While both lens care systems performed well with the SiH lenses used, the H2O2 resulted in a longer reported comfortable wearing time then the MPDS.

Tear film dynamics and lipid layer characteristics—Effect of age and gender - Corrected Proof

Cécile Maïssa, Michel Guillon — 2010-03-04

Abstract: Purpose: Dry eye disease is significantly more prevalent in older subjects and among them more marked in women than men. Further, it is established that the tear film dynamics of dry eye sufferers is different to that of normal. It is therefore postulated that the greater prevalence of dry eye problems with advancing age is at least in part related to poorer tear film dynamics.Methods: Tear film dynamics (non-invasive break up time) and lipid characteristics (lipid layer thickness and contamination) were assessed using the Tearscope lighting system.Results: 160 Subjects less than 45 years old and 58 subjects aged 45 years or more formed the study populations. The tear film stability was mostly influenced by age; the break up time was statistically significantly shorter for the older age group (p<0.001). The lipid layer was also significantly thinner (p=0.013) for the subjects aged 45 years or older with a very marked synergic effect of age and gender. The lipid layer of older women was significantly thinner and more contaminated than that of younger women (p=0.002 and <0.001) and of older men (p=0.034 and 0.004).Conclusions: Aging of the tear film is characterised by its destabilisation associated with significant changes in the tear lipid layer producing less protection from evaporation in the older population; the observed changes are more marked in women than in men. The findings have significant implications for the management of presbyopic dry eye sufferers, for whom decreasing evaporative problems is essential.

The use of video-keratoscopy in predicting contact lens parameters for keratoconic fitting - Corrected Proof

Luigina Sorbara, Kristine Dalton — 2010-02-04

Abstract: Purpose: The purpose of this report is to demonstrate the use the video-keratoscope in determining the type and size of the cone in keratoconus and PMD patients and the final back optic zone diameter (BOZD) and total lens diameter (LD).Methods: A retrospective review of one hundred clinical records including topographic maps, of keratoconic patients (randomly selected) was performed. Cone diameter and type and final contact lens base curve and diameter were recorded.Results: The types or variations of keratoconus were determined with the use of the tangential map to be either: centred or nipple, early oval cones, moderate oval cones, severe cones or pellucid marginal degeneration (PMD). The size of the cone was dependent on the type and the stage of progression of the cone. Inventory sets for keratoconus that had progressively smaller BOZDs as the base curve or back optic zone radius (BOZR) steepened were found to fit best when prescribed for centred or nipple cones. Inventory sets or multicurve sets that had a constant BOZD with a certain lens diameter that did not vary with the BOZR were found to perform better on oval cones. Very large cones, as with PMD benefited from lenses with very large BOZDs.Conclusions: Matching the size of the BOZD (and in tandem the LD) to the size of the cone as determined with the tangential topographic map may be a useful tool in aiding in contact lens fitting to increase success.

Attitudes towards contact lenses: A comparative study of teenagers and their parents - Corrected Proof

2010-01-18

Abstract: Purpose: This two-phase survey aimed to identify the beliefs and attitudes that create a barrier towards contact lens (CL) fitting among adolescents (aged 12–18 years) and their parents attending eye care practitioner clinics in Italy (phase 1) and Iberia (Spain and Portugal; phase 2). In phase 2, the sample was further focused, by limiting it to those adolescents who did not already wear CL.Methods: The extent to which CL satisfy aesthetic, visual, and practical needs and their effectiveness, safety, and comfort in the general population and in adolescents was rated by respondents on a 5-point Likert scale.Results: In phase 1, approximately one-third of adolescents (n=146) and parents (n=114) were CL wearers. Most adolescents (77.5% of 223) and parents (66.2% of 230) expressed a high interest in CL use in phase 2 despite none of the adolescents currently wearing CL. Parents, but not adolescents, perceived that CL were significantly less safe in adolescents than in the general population (p<0.05) in phases 1 and 2. Across both phases, adolescents and parents agreed that CL met an aesthetic need in adolescents (p<0.05 versus general population). Among 50% of parents (mainly mothers), significant concerns regarding CL were difficulties following instructions and taking care of the CL and potential eye damage, which, in mothers, led them to show less agreement towards CL use by the adolescent (p<0.001).Conclusions: These findings highlight an essential need for improved education on CL use in the population.

Effect of weathering and thickness on roughness of acrylic resin and ocular button - Corrected Proof

2010-01-14

Abstract: Purpose: The aim of this study was to evaluate the roughness of colorless ocular button and four brands of colorless acrylic resins designed to fabricate ocular prosthesis as a function of weathering (1008h) and different thickness (1 and 3.5mm).Materials and methods: One-hundred-and-twenty specimens were fabricated and distributed in 12 groups. The analysis was carried out by means of digital roughness meter.Results: Data were analyzed statistically by ANOVA and Tukey test at 1% significance. The results showed that there was no statistically significant difference after the weathering period. Both the Vipi Cril acrylic resin with 3.5mm in thickness and ocular button with 1mm in thickness presented the lowest roughness values (0.12Ra).Conclusion: The roughness of the acrylic resins and the ocular button was not affect by the weathering of 1008h. However, the thickness of the specimens proved to have a major influence on roughness property.

Break in microkeratome oscillating pin during LASIK flap creation - Corrected Proof

Chandrashekar Balachandran, Ioannis M. Aslanides — 2010-01-07

Abstract: We describe the case of a 40-year-old female myope who presented for bilateral LASIK. Intra-operatively, the microkeratome oscillating pin broke during flap creation resulting in the separation of the disposable blade from the motor. This resulted in an irregular flap with missing pieces. The procedure was abandoned and the macerated partial flap repositioned as best as possible. The patient recovered a BCVA of 6/7.5. The manufacturer has since reported taking corrective measures to prevent this problem in the future. This case is a reminder that despite care and maintenance by user and manufacturer, extreme and rare hardware malfunctions can occur. Furthermore, although potentially sight threatening if managed well these complications can be followed by good recovery of vision.

Twenty first century trends in silicone hydrogel contact lens fitting: An international perspective - Corrected Proof

2010-01-07

Abstract: Silicone hydrogel contact lenses were introduced into the market in 1999. To assess prescribing trends of this lens type since then, up to 1000 survey forms were sent to contact lens fitters in Australia, Canada, Japan, the Netherlands, Norway, the UK and the USA each year between 2000 and 2008. Practitioners were asked to record data relating to the first 10 contact lens fits or refits performed after receiving the survey form. Analysis of returned forms revealed a rapid increase in the prescribing of silicone hydrogel lenses over the survey period. In 2008, silicone hydrogel lenses represented 36% of all soft lenses prescribed. The categorization of the majority of lenses prescribed as ‘refits’ is primarily attributed to the mass conversion of lens wearers from hydrogel to silicone hydrogel lenses. Silicone hydrogels may soon represent the majority of soft contact lenses prescribed.

A comparison of a topography-based rigid gas permeable contact lens design with a conventionally fitted lens in patients with keratoconus - Corrected Proof

Nawtej S. Bhatoa, Scott Hau, Daniel P. Ehrlich — 2010-01-06

Abstract: Purpose: To determine if a clinically comparable contact lens could be designed for patients with keratoconus utilising a corneal topographer and its contact lens design software.Methods: A total of 30 patients with keratoconus were recruited for this randomized, double-masked prospective study. Corneal topography was performed on each patient using the Orbscan II (Bausch & Lomb, NY, USA) topographer. The topographers’ Fitscan RGP fitting software was used to derive a tri-curve rigid contact lens specification. This was manufactured, and then compared by three experienced clinicians with the patients’ conventionally fitted (habitual) lens. Each aspect of contact lens fitting was graded, and each grade was weighted for kappa analysis to determine if there was any significant difference between the Fitscan-derived lens and the patients’ habitual lens.Results: Percentage agreement levels between the two fitting techniques were between 74% and 100%. Kappa values varied from below 0 to 0.60, indicating poor to moderate agreement. A slight bias towards flatter apical fitting in the Fitscan design was found in some cases of advanced keratoconus. There was no systematic bias for either fitting technique when comparing visual performance and lens comfort. A higher percentage of Fitscan-derived lenses were deemed suitable to dispense to patients, either directly or after minor parameter modification.Conclusion: This study demonstrates that a satisfactory lens design for keratoconic patients can be produced utilising a topography-based system, when compared to a patients’ conventionally fitted lens. The potential advantages of this system include simplified lens selection and reduced trial lens usage, with a reduction in patient discomfort, clinical chair-time and costs.

Current silicone hydrogel UVR blocking lenses and their associated protection factors - Corrected Proof

Karen S. DeLoss, James E. Walsh, Jan P.G. Bergmanson — 2009-12-30

Abstract: Purpose: Ultraviolet radiation (UVR) blocking contact lenses provides ocular protection factors (PF) that vary with lens thickness and the nature of the polymer dopant. This study measured the UVR PF of silicone hydrogel lenses outdoors and compares this to known methods for determining PF mathematically.Methods: Ambient measurements were taken using an UVA-B radiometer, adapted to hold the test lenses over its sensor to quantify their UVR blocking capabilities. The UVR blocking silicone hydrogel lenses tested included galyfilcon A, senofilcon A, and enfilcon A. The first UVR blocking hydrogel lens, vasurfilcon A, and a non-blocking silicone hydrogel lens, lotrafilcon B, served as a comparison. Lens transmittance at the centre and periphery was measured and PF calculated to predict signal reduction for comparison with field measurements.Results: There was a significant range of cut-off wavelengths across the lenses, ranging from 370nm for enfilcon A to 390nm for vasurfilcon A, with lotrafilcon B transmitting down to 265nm, with a 3nm shift from centre to periphery across the −3.00 D UVR blockers. The UVR reduction calculated from the transmittance data correlates well with field data, ranging from 90–98% for the UVR blockers to 13% for the non-blocker.Conclusions: The silicone hydrogel lenses showed a wide range of transmittance curves with increasing PF from centre to periphery. PF calculations work well but do not always compare precisely with measured data due to factors such as sensor spectral response and the nature of the incident solar spectrum.

International rigid contact lens prescribing - Corrected Proof

2009-12-25

Abstract: Rigid lenses have been fitted less since the introduction of soft lenses nearly 40 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 facilitate an accurate characterization of the pattern of the decline of rigid lens fitting during the first decade of this century. There is a trend for rigid lenses to be utilized primarily for refitting those patients who are already successful rigid lens wearers—most typically older females being refit with higher Dk materials. Rigid lenses are generally fitted on a full-time basis (four or more days of wear per week) without a planned replacement schedule. Orthokeratology is especially popular in the Netherlands, but is seldom prescribed in the other countries surveyed.