BCLA CLEAR Presbyopia: Management with contact lenses and spectacles.

This paper seeks to outline the history, market situation, clinical management and product performance related to the correction of presbyopia with both contact lenses and spectacles. The history of the development of various optical forms of presbyopic correction are reviewed, and an overview is presented of the current market status of contact lenses and spectacles. Clinical considerations in the fitting and aftercare of presbyopic contact lens and spectacle lens wearers are presented, with general recommendations for best practice. Current options for contact lens correction of presbyopia include soft simultaneous, rigid translating and rigid simultaneous designs, in addition to monovision. Spectacle options include single vision lenses, bifocal lenses and a range of progressive addition lenses. The comparative performance of both contact lens and spectacle lens options is presented. With a significant proportion of the global population now being presbyopic, this overview is particularly timely and is designed to act as a guide for researchers, industry and eyecare practitioners alike.

Multifocal contact lens success predictability.

PURPOSE: The current multi-study analysis combined data from three studies to quantify the relationship between the initial reaction to soft multifocal contact lens (MFCL) design types at dispensing and evaluate the predictability of overall vision satisfaction (OVS) and intention to purchase (ITP) after 1 week of wear. METHOD: Three prospective studies tested MFCLs over 1-week of wear following the same protocol, using a range of potentially predictive ratings at dispensing, and both OVS and ITP at 1-week as an indicator acceptance level. In each study, two of MyDay® multifocal, clariti® 1 day multifocal, Biofinity® multifocal (worn as a daily disposable lens) or 1 DAY ACUVUE® MOIST MULTIFOCAL were dispensed for 1-week of daily wear. OVS was recorded on a 100-point VAS and ITP on a 5-point LIKERT scale. Fourteen possible predictors were entered in the statistical model, and predictability was assessed using Chi-square Automatic Interaction Detector (CHAID) statistical test. RESULTS: A total of 210 participants (152 female & 58 male; 53.9 ± 6.5 years, range 41-71 years), representing 420 MFCL fits, equally distributed between emergent n = 65, established n = 70 and advanced n = 75 presbyopes, completed the studies. OVS on dispensing was the predictor of both OVS (p < 0.001) and ITP (p < 0.001) at 1-week. For OVS predictability, 70.8 % with OVS at dispensing > 91 points reported good OVS at 1-week and 73.4 % with OVS on dispensing ≤ 80 points reported poor OVS at 1-week. For ITP predictability, 74.6 % with OVS at dispensing > 94 points reported a positive ITP at 1-week and 65.9 % with OVS on dispensing ≤ 63 points reported negative ITP at 1-week. CONCLUSION: Overall vision satisfaction at the time of dispensing MFCLs is a powerful indicator of both OVS and ITP after 1-week of wear. Initial patient subjective assessments provide a clinically useful indicator of the likeliness of success.

Six years of wearer experience in children participating in a myopia control study of MiSight® 1 day.

PURPOSE: To evaluate the experience of children wearing soft contact lenses (CLs) during a trial of MiSight® 1 day (omafilcon A, CooperVision, Inc.), a dual-focus myopia-control daily disposable CL. METHODS: A 3-year, double-masked, randomised trial (Part 1) comparing experiences with MiSight 1 day and a single-vision control (Proclear® 1 day, omafilcon A, CooperVision, Inc.) of neophyte, myopic children (ages 8-12). Treatment (n = 65) and control (n = 70) participants received lenses at sites in Canada, Portugal, Singapore, and the UK. Successful participants completing Part 1 were invited to continue for a further 3 years wearing the dual-focus CL (Part 2), and 85 participants completed the 6-year study. Children and parent questionnaires were conducted at baseline, 1 week, 1 month, and every 6 months until the 60-month visit, with children only also completing questionnaires at 66 and 72 months. RESULTS: Throughout the study, children reported high satisfaction with handling (≥89% top 2 box [T2B]), comfort (≥94% T2B), vision (≥93% T2B for various activities), and overall satisfaction (≥97% T2B). Ratings for comfort and vision were not significantly different between lens groups, visits, or study parts and did not change when children switched to dual-focus CLs. Ratings for 'really easy' or 'kind of easy' application improved from the outset for the neophytes (57% at 1-week follow-up and 85% at 1-month follow-up) and remained high throughout the study (visit: P = 0.007; part: P = 0.0004). Overall satisfaction improved in Part 2 (P = 0.04). Wearing times increased in Part 2 (14 vs. 13 hrs/weekday; 13 vs. 12 hrs/day on weekends; P < 0.001); there were no differences between groups. CONCLUSIONS: Children adapted rapidly to full-time wear, rated lenses highly, and rarely reported issues. The dual-focus optics included in the MiSight® 1 day lenses successfully achieved myopia control without lowering subjective ratings when fitted to neophytes or children refitted from single-vision CLs.

Challenges to the new soft contact lens wearer and strategies for clinical management.

Soft contact lens discontinuations have a dramatic impact on the overall success of this form of vision correction, and evidence suggests that the reasons for contact lens cessation are different for new wearers than for established lens users. In descending order, these relate to vision, discomfort, handling, inconvenience/loss of interest, ocular health and cost. This paper considers the background and underlying evidence for these causes of soft lens discontinuation in new wearers, and presents clinical management strategies to minimise this phenomenon. Such measures can reasonably be expected to significantly reduce the number of contact lens discontinuations leading to happier patients, increased satisfaction for eye care professionals (ECPs), and greater success for both individual practices and the contact lens industry more broadly.

Wearer Experience and Eye Care Professional Acceptance with a 1 Day Multifocal Contact Lens.

Purpose: A large observational survey was undertaken to determine eye care professional (ECP) and patient experience of stenfilcon A multifocal soft contact lens (MyDay multifocal) when prescribed in a real-world setting. Methods: A total of 196 ECPs from eleven countries fit up to ten presbyopes with stenfilcon A multifocal. Data were collected on fit success at the initial visit, patient satisfaction with comfort, vision at distance, intermediate, and near, overall vision, overall satisfaction, and handling at the initial and follow-up visits after 1-2 weeks of wear. ECPs completed questionnaires on multifocal fitting experience and expectations before and after the fitting period. Results: A total of 196 pre-fitting and 141 post-fitting ECP surveys were collected. A total of 1505 initial fits (mean age 53.4, range 38 to 81 years, 73% female, 27% neophytes) and 1440 follow-up visits were completed. The mean distance vision contact lens prescription was -1.32DS (range -12.00DS to +8.00DS) with Add powers: Low 56%, Medium 24%, and High 21%. At the follow-up visit 77% (n=1108) of trials were successful. Mean patient satisfaction ratings (1-10 scale, where 1 is not at all satisfied, and 10 extremely satisfied) at the initial visit were higher than eight out of ten for comfort, vision, and overall satisfaction, and were not significantly different after 1-2 weeks of wear. Stenfilcon A multifocal was preferred by 66% of patients over their habitual correction. In most cases mean satisfaction scores and the proportion of patients highly satisfied were not significantly different between myopes and hyperopes, across Add range, between new and habitual wearers, and wearers of frequently replaced and 1 day contact lenses. Conclusion: ECPs in real-world clinical settings found stenfilcon A multifocal contact lenses easy to fit to a wide range of patients, with a high fit success rate and high levels of patient satisfaction for overall comfort, vision, satisfaction, and handling.

An investigation into disposal and recycling options for daily disposable and monthly replacement soft contact lens modalities.

PURPOSE: To examine the annualised waste and end-of-life disposal options with two representative soft contact lens (CL) modalities. METHODS: The component parts of two representative soft CL modalities were catalogued, separated, weighed and inspected for material identification: somofilcon A soft CLs (clariti elite, CooperVision Inc.) used with multi-purpose solution (MPS) (All in one Light, CooperVision Inc.) and somofilcon A CLs (clariti 1 day, CooperVision Inc). Using a model that assumed compliant wear and care of CLs, the mass of material solid waste generated by CL use over a year was calculated. Disposal options were explored using household and specialist recycling streams in order to develop recommendations for responsible disposal of CL waste. RESULTS: Full-time daily disposable (DD) CL wear generates 1.06 kg of waste annually compared to 0.83 kg generated by reusable-monthly replacement daily wear ('reusable') CLs. Plastic was the dominant material in both modalities. With full-time use of DD CLs, 64% of waste by mass was plastic blister trays. For full-time use of reusable CLs, where figures from lens and MPS packaging are combined, plastics accounted for 67% of waste by mass. MPS bottles alone made up almost half the waste (45%) associated with full-time reusable CL wear. CONCLUSION: Full-time DD wear generates 27% more waste annually than full-time reusable lens wear. Reusable CL wearers can recycle 78% of waste at home. DD lens wearers have access to recycling options that allow them to recycle 100% of CL related waste. Full-time CL lens wear represents just 0.20-0.26% of the 412 kg of household waste generated per person, per year in the United Kingdom. Worn CLs should never be disposed of down the sink or lavatory. CL wearers should be aware of responsible end-of-life recycling and disposal options for all CL waste.

CLEAR - Evidence-based contact lens practice.

Evidence-based contact lens -->practice involves finding, appraising and applying research findings as the basis for patient management decisions. These decisions should be informed by the strength of the research study designs that address the question, as well as by the experience of the practitioner and the preferences and environment of the patient. This reports reviews and summarises the published research evidence that is available to inform soft and rigid contact lens history and symptoms taking, anterior eye health examination (including the optimised use of ophthalmic dyes, grading scales, imaging techniques and lid eversion), considerations for contact lens selection (including the ocular surface measurements required to select the most appropriate lens parameter, lens modality and material selection), evaluation of lens fit, prescribing (teaching self-application and removal, adaptation, care regimen and cleaning instructions, as well as -->minimising risks of lens wear through encouraging compliance) and an aftercare routine.

Silicone hydrogel daily disposable benefits: The evidence.

Daily disposable (DD) contact lenses first came to the market approximately 25 years ago and eye care professionals (ECPs) started prescribing silicone hydrogel (SiH) contact lenses, primarily for extended or continuous wear, approximately 20 years ago. It has now been over ten years since SiH DD contact lenses have been available, and while SiH materials are routinely prescribed by ECPs for reusable daily wear, hydrogel materials are still frequently selected for the DD modality of contact lens wear. This article reviews the evidence to support the benefits of both a DD modality and SiH materials and how patients' needs may be met with SiH DD contact lenses, with respect to clinical performance, health outcomes, satisfaction, compliance and convenience. Factors which may enable or constrain ECPs from prescribing SiH DD contact lenses, as opposed to hydrogel DD and reusable contact lenses, for more of their patients are discussed with the objective of providing ECPs with a greater understanding of the advantages that can be afforded by prescribing SiH DD contact lenses to both their new and existing contact lens wearers.

Management of digital eye strain.

Digital eye strain, an emerging public health issue, is a condition characterised by visual disturbance and/or ocular discomfort related to the use of digital devices and resulting from a range of stresses on the ocular environment. This review aims to provide an overview of the extensive literature on digital eye strain research with particular reference to the clinical management of symptoms. As many as 90 per cent of digital device users experience symptoms of digital eye strain. Many studies suggest that the following factors are associated with digital eye strain: uncorrected refractive error (including presbyopia), accommodative and vergence anomalies, altered blinking pattern (reduced rate and incomplete blinking), excessive exposure to intense light, closer working distance, and smaller font size. Since a symptom may be caused by one or more factors, a holistic approach should be adopted. The following management strategies have been suggested: (i) appropriate correction of refractive error, including astigmatism and presbyopia; (ii) management of vergence anomalies, with the aim of inducing or leaving a small amount of heterophoria (~1.5Δ Exo); (iii) blinking exercise/training to maintain normal blinking pattern; (iv) use of lubricating eye drops (artificial tears) to help alleviate dry eye-related symptoms; (v) contact lenses with enhanced comfort, particularly at end-of-day and in challenging environments; (vi) prescription of colour filters in all vision correction options, especially blue light-absorbing filters; and (vii) management of accommodative anomalies. Prevention is the main strategy for management of digital eye strain, which involves: (i) ensuring an ergonomic work environment and practice (through patient education and the implementation of ergonomic workplace policies); and (ii) visual examination and eye care to treat visual disorders. Special consideration is needed for people at a high risk of digital eye strain, such as computer workers and contact lens wearers.

Retention Rates in New Contact Lens Wearers.

PURPOSE: To determine the retention rate (RR) for neophyte patients fitted with contact lenses (CLs) and to identify factors associated with retention and dropout. METHOD: This multisite, sponsor-masked registry study evaluated the 1-year status of neophyte CL wearers fitted in a representative range of UK practices. A total of 26 UK investigational sites each recruited up to 89 neophyte patients. The participants were requested to complete surveys at 1 month (±1 week from date of fitting), 3 months (±2 weeks), and 12 months (±3 weeks) online or through phone. Participants were contacted by email (or phone) and invited to complete an online survey that asked a range of questions regarding their CL wearing experience. RESULTS: Of the 531 participants recruited, 65.3% (347/531) responded to at least one follow-up survey and 42.3% (225/531) responded to all three surveys. One in four patients showed discontinued CL wear by 12 months. Based on evaluable subjects at 12 months, the RR was 77.6% (194/250, 95% confidence interval: 72.0-82.3). The most common reason for discontinuation was problems with vision (41%), followed by discomfort (36%) and handling problems (25%). The factors affecting first-year RRs: sex, spherical refraction, lens usage (full time or part time), and supply method (collected or posted). CONCLUSIONS: In this prospective study, the first-year RR for neophyte CL wearers was 77.6%. This was consistent with that noted in a retrospective study: 74.0%. As with the previous study, the commonly cited reason for discontinuation was visual problems.

Theoretical fitting characteristics of typical soft contact lens designs.

PUROSE: To calculate theoretical fitting success rates (SR) for a range of typical soft contact lens (SCL) designs using a mathematical model. METHOD: A spreadsheet mathematical model was used to calculate fitting SR for various SCL designs. Designs were evaluated using ocular topography data from 163 subjects. The model calculated SR based on acceptable edge strain (within range 0-6%) and horizontal diameter overlap (range 0.2-1.2mm). Where lenses had multiple base curves (BCs), eyes unsuccessful with the steeper BC were tested with the flatter BC and aggregate SR calculated. Calculations were based on typical, current, hydrogel and silicone hydrogel SCLs and allowed for appropriate on-eye shrinkage (1.0-2.3%). Theoretical results were compared with those from actual clinical trials. RESULTS: Theoretical success rates for one-BC lenses ranged from 60.7% (95% CI 7.2%) to 90.2% (95% CI 3.7%). With two-BC designs, most combinations showed a SR increase with a second BC (84.0%-90.2%). However, one of the two-BC combinations showed only negligible increase with a second BC (72.4%-73.0%). For designs with lower SR, the greatest contributor to failure was inadequate lens diameter. For a given design, differences in shrinkage (i.e. on-eye bulk dehydration) had a significant effect on success rate. In comparison with historical clinical data, there was a positive correlation between small lens fitting prevalence and discomfort reports (r=+0.95, P=<0.001) with a poor correlation between theoretical and actual tight/loose fittings. CONCLUSIONS: Mathematical modelling is a useful method for testing SCL design combinations. The results suggest that judicious choice of additional fittings can expand the range of fitting success.

Inter-relationship of Soft Contact Lens Diameter, Base Curve Radius, and Fit.

PURPOSE: To evaluate the inter-relationship of soft contact lens base curve radius (BC), diameter, and lens fit using a mathematical model. METHODS: A spreadsheet mathematical model was used to evaluate theoretical fitting characteristics for various combinations of soft lens BC and diameter. The designs were evaluated using ocular topography data collected from 163 UK subjects. The model evaluated lens tightness (edge strain) and on-eye diameter (horizontal corneal overlap) and assumed that acceptable values fell within the range 0 to 6% and 0.2 to 1.2 mm, respectively. Analyses were undertaken of various trends relating to soft lens fit, including (1) the effect of BC and diameter on fitting success; (2) the effect of lens asphericity, BC, and sag on lens diameter on the eye; and (3) the effect of lens diameter on lens tightness. RESULTS: The highest overall success rate (90.2%) was achieved with an 8.60/14.2 mm (BC/diameter) design. Using this design on the sample population, the median edge strain value was 3.2% (IQR: 2.1%) whereas median corneal overlap was 0.62 mm (IQR: 0.35). There was a positive correlation (r = 0.37, P < .0001) between edge strain and corneal overlap. Edge strain showed significant correlations with each of the ocular topography variables, most notably corneal asphericity (-0.62, P < .0001). Corneal overlap showed significant correlations with corneal asphericity (r = -0.42, P < .0001) and corneal diameter (r = 0.92, P < .0001). For a 0.4 mm change in BC, it is necessary to change diameter by 0.2 mm to maintain similar on-eye diameter (arclength). When changing lens diameter, a change in BC of 0.2 mm is required to maintain similar tightness of fit. CONCLUSIONS: Mathematical modeling is a useful technique for large-scale evaluation of the interactions of soft contact lens design and fit. The study has given useful insights into the general performance of soft lens designs.

Factors in the success of new contact lens wearers.

PURPOSE: To determine the first-year retention rate for patients fitted with contact lenses (CLs) and identify factors associated with retention and dropout. METHODS: This multi-site study was a retrospective chart review of the status of neophyte CL wearers fitted in representative UK eye care practices. RESULTS: Consecutive records for 524 patients at 29 sites were reviewed. Mean age at dispensing was 34 years (range 8-79), 68% were under 45 years and 61% female. Soft CLs were fitted to 98% of patients. After 12 months, 388 were still CL wearers, a retention rate of 74% (95% CI: 70.1-77.6). Of the 136 lapsed, 25% discontinued during the first month and 47% within 60 days. The main reasons cited for discontinuation included poor distance vision (26%; of whom, 37% were toric and 51% multifocal), poor near vision (16%), discomfort (14%) and handling problems (15%). In 32% of cases, the reasons for discontinuation were unknown. For 71% of dropouts, no alternative lens or management strategy had been tried. Significant factors associated with retention in univariate analysis were: age (younger), sphere power (higher), lens type (sphere vs multifocal) and purchase frequency (regular). Multivariate analysis showed lens sphere power, purchase frequency and lens material to be significant factors. There was a wide variation in retention rates between sites (40-100%). CONCLUSIONS: During the first year of CL wear, the overall retention rate for neophyte CL wearers was 74% (spherical CLs 79%, torics 73%, multifocals 57%), with many lapsing during the first 2 months. Factors associated with retention and dropout in these patients include: lens power, material and type, and purchase frequency. While handling and comfort are the most commonly cited performance-related reasons for discontinuing in new spherical lens wearers, visual problems are the most common among new wearers of toric and, in particular, multifocal CLs.

Demonstrating correction of low levels of astigmatism with realistic scenes.

PURPOSE AND METHOD: Modern standard visual acuity tests are primarily designed as diagnostic tools for use during subjective refraction and normally bear little relation to real-world situations. We have developed a methodology to create realistic rendered scenes that demonstrate potential vision improvement in a relevant and engaging way. Low-cylindrical refractive error can be made more noticeable by optimizing the contrast and spatial frequencies, and by testing four different visual perception skills: motion tracking, pattern recognition, visual clutter differentiation and contrast sensitivity. Using a 1.00DC lens during iteration, we created a range of still and video scenes before optimizing to a selection 3-D rendered street scenes. These were assessed on everyday relevance, emotional and visual engagement and sensitivity to refractive correction for low-cylinder astigmats (0.75-1.00DC, n=74) wearing best spherical equivalent correction and then with astigmatism corrected. RESULTS AND CONCLUSIONS: The most promising visual elements involved or combined optimized textures, distracting patterns behind text, faces at a distance, and oblique text. 91.9% of subjects (95% CI: 83.2, 97.0) reported an overall visual improvement when viewing the images with astigmatic correction, and 96% found the images helpful to determine which type of contact lens to use. Our method, which combines visual science with design thinking, takes a new approach to creating vision tests. The resultant test scenes can be used to improve patient interaction and help low cylinder astigmats see relevant, every-day benefits in correcting low levels (0.75 & 1.00DC) of astigmatism.

The Effect of Temperature on Soft Contact Lens Diameter.

PURPOSE: The diameters of soft contact lenses are conventionally measured at room temperature (RT), however, all soft lenses shrink when raised to eye temperature (ET). The purpose of this study was to evaluate RT to ET shrinkage in a representative sample of contemporary spherical soft contact lenses. METHODS: Twenty-four reusable and daily disposable lens types (10 hydrogel and 14 silicone hydrogel) in three powers were measured for total diameter at RT (20°C±1°C) and ET (34°C±1°C). Lens diameter measurements were undertaken after equilibration in ISO saline in a temperature controlled lens analyzer (Optimec Ltd, Malvern, UK). Theoretical changes in base curve radii were also calculated. RESULTS: All lens types reduced in diameter when raised to ET. The largest mean changes with silicone hydrogel and hydrogel lenses were with Avaria (Δ0.33 mm) and SofLens Daily Disposable (Δ0.69 mm), respectively. The smallest mean changes for silicone hydrogel and hydrogel lenses were with 1-DAY ACUVUE TruEye (Δ0.04 mm) and SofLens 38 (Δ0.11 mm), respectively. There was, however, a wide range in change between the different lenses tested. CONCLUSIONS: This study has identified the levels of shrinkage in current soft contact lenses. In many cases, these shrinkage levels can be expected to have significant effects on clinical performance.

Resultant vertical prism in toric soft contact lenses.

PURPOSE: Rotational stability of toric soft contact lenses (TSCLs) is achieved using a range of designs. Designs utilising prism or peripheral ballast may result in residual prism in the optic zone. This study quantifies the vertical prism in the central 6mm present in TSCLs with various stabilisation methods. METHOD: Vertical prism was computed using published refractive index and vertical thickness changes in the central optic zone on a full lens thickness map. Thickness maps were measured using scanning transmission microscopy. Designs tested were reusable, silicone hydrogel and hydrogel TSCLs: SofLens(®) Toric, PureVision(®)2 for Astigmatism, PureVision(®) Toric, Biofinity(®) Toric, Avaira(®) Toric, clariti(®) toric, AIR OPTIX(®) for ASTIGMATISM and ACUVUE OASYS(®) for ASTIGMATISM; with eight parameter combinations for each lens (-6.00DS to +3.00DS, -1.25DC, 90° and 180° axes). RESULTS: All TSCL designs evaluated had vertical prism in the optic zone except one which had virtually none (0.01Δ). Mean prism ranged from 0.52Δ to 1.15Δ, with three designs having prism that varied with sphere power. Vertical prism in ACUVUE OASYS(®) for ASTIGMATISM was significantly lower than all other TSCLs tested. CONCLUSIONS: TSCL designs utilising prism-ballast and peri-ballast for stabilisation have vertical prism in the central optic zone. In monocular astigmats fitted with a TSCL or those wearing a mix of toric designs, vertical prism imbalance could create or exacerbate disturbances in binocular vision function. Practitioners should be aware of this potential effect when selecting which TSCL designs to prescribe, particularly for monocular astigmats with pre-existing binocular vision anomalies, and when managing complaints of asthenopia in monocular astigmats.

Conjunctival UV autofluorescence--prevalence and risk factors.

PURPOSE: Autofluorescence of ultraviolet (UV) light has been shown to occur in localised areas of the bulbar conjunctiva, which map to active cellular changes due to UV and environmental exposure. This study examined the presence of conjunctival UV autofluorescence in eye care practitioners (ECPs) across Europe and the Middle East and its associated risk factors. METHOD: Images were captured of 307 ECPs right eyes in the Czech Republic, Germany, Greece, Kuwait, Netherlands, Sweden, Switzerland, United Arab Emirates and the United Kingdom using a Nikon D100 camera and dual flash units through UV filters. UV autofluorescence was outlined using ImageJ software and the nasal and temporal area quantified. Subjects were required to complete a questionnaire on their demographics and lifestyle including general exposure to UV and refractive correction. RESULTS: Average age of the subjects was 38.5±12.2 years (range 19-68) and 39.7% were male. Sixty-two percent of eyes had some conjunctival damage as indicated by UV autofluorescence. The average area of damage was higher (p=0.005) nasally (2.95±4.52mm(2)) than temporally (2.19±4.17mm(2)). The area of UV damage was not related to age (r=0.03, p=0.674), gender (p=0.194), self-reported sun exposure lifestyle (p>0.05), geographical location (p=0174), sunglasses use (p>0.05) or UV-blocking contact lens use (p>0.05), although it was higher in those wearing contact lenses with minimal UV-blocking and no spectacles (p=0.015). The area of UV damage was also less nasally in those who wore contact lenses and spectacles compared to those with no refractive correction use (p=0.011 nasal; p=0.958 temporal). CONCLUSION: UV conjunctival damage is common even in Europe, Kuwait and UAE, and among ECPs. The area of damage appears to be linked with the use of refractive correction, with greater damage nasally than temporally which may be explained by the peripheral light focusing effect.

Clinical evaluation of fitting toric soft contact lenses to current non-users.

PURPOSE: To evaluate the ease with which astigmats from three groups of current non-wearers of toric contact lenses can be fitted with current toric soft lenses, and to determine toric lens-wearing success. METHODS: This was a 1-month, randomized, bilateral, open-label, daily wear study involving 200 subjects and 16 investigational sites in the UK. Three groups of astigmatic subjects aged from 16 to 60 and with a mean age of 36 years (67 spherical soft contact lens users, SW; 72 contact lens drop-outs, DO; and 61 neophytes, Neo) were fitted with one of two toric soft lens types: a daily disposable toric soft lens (1 Day Acuvue Moist for Astigmatism, Johnson & Johnson Vision Care) or a 2-weekly replacement, re-usable toric soft lens (Acuvue Oasys for Astigmatism, Johnson & Johnson Vision Care). Subjects were evaluated after 1 month of wear and success rates calculated according to pre-set criteria for acceptable fit, orientation stability, visual acuity, quality of vision, and overall comfort. RESULTS: Eighty-eight percent of lenses were fitted at the first attempt. Of 198 subjects dispensed with lenses, 182 (92%) completed the study. When analysed by subject group, the success rates according to the pre-set criteria were 80% (53/66), 74% (52/70), and 70% (39/56) for the SW, DO and Neo groups respectively. Comfort was the most common reason for failure with all three groups; however, visual problems were more common in the DO and Neo groups (13% vs 6%). VA with the study lenses was significantly better in the SW group compared to their habitual lenses. For the DO and Neo groups combined (i.e. spectacle wearers), visual acuity was comparable to their habitual spectacles. CONCLUSIONS: A high proportion of astigmats who are not using toric soft contact lenses can be fitted with current lenses. Previous contact lens drop-outs and neophyte wearers achieve visual acuity comparable to spectacles when fitted with toric soft lenses. Spherical contact lens wearing astigmats achieve superior visual acuity when refitted with toric soft lenses. These findings suggest that many astigmats who are not currently using toric soft contact lenses could do so successfully.

Prevalence of astigmatism in relation to soft contact lens fitting.

PURPOSE: To estimate the proportion of potential soft contact lens wearers requiring an astigmatic correction and to estimate the proportion of astigmats who can be accommodated with toric soft lenses of varying prescription range. METHOD: A database of 11,624 spectacle prescriptions was used to calculate the prevalence of astigmatism for various thresholds (0.50-2.00 DC) by eye and by patient. The coverage of various prescription ranges was estimated using a subset of the database comprising those patients with at least 0.75 D of astigmatism in at least one eye (n = 5,444). RESULTS: The prevalence of patients showing astigmatism of 0.75 and 1.00 D or greater in at least one eye was 47.4% and 31.8% and, in both eyes, 24.1% and 15.0%, respectively. The proportion of eyes showing astigmatism greater than or equal to 0.75, 1.00, 1.50, and 2.00 D was 35.7%, 23.4%, 10.8%, 5.6%, respectively. The prevalence of astigmatism of 0.75 D or greater was almost double in myopes compared with hyperopes: 31.7% vs. 15.7%. The prevalence of with-the-rule (WTR) astigmatism was higher than against-the-rule (32.9% vs. 29.1%); the proportion was also higher for WTR in eyes with astigmatism ≥0.75 D (15.3% vs. 14.5%). We estimate that approximately one third of potential contact lens wearers require astigmatic correction. A stock range of toric soft lenses in sphere powers +6.00 to -9.00 D, three cylinder powers, and 18 axes requires nearly 3,000 prescriptions and provides coverage for 90% of astigmats. CONCLUSION: These findings provide an estimate of the proportion of soft contact lens patients requiring an astigmatic correction and some useful insights into the proportion of astigmats covered by toric soft lens stocks of varying range.