Predicted tear layer oxygen tensions under two designs of silicone hydrogel toric lenses

Introduction

The goal of this study was to apply a theoretical analysis of the relationship between contact lens oxygen transmissibility and tear layer oxygen tension to silicone hydrogel toric lenses and thereby model the success of such lenses in decreasing corneal hypoxia.

Method

Lens thickness was measured at different points along the vertical meridian of one prism-ballasted, one dynamic-stabilized silicone hydrogel toric lens design, and one control “traditional” hydrogel toric lens design. Using lens thickness measurements and the nominal oxygen permeability values of these three lens designs, the subsequent oxygen tension in the tear layer trapped between the contact lens and the anterior cornea (P2) were calculated for both open- and closed-eye conditions using a single corneal chamber model with a personal computer program.

Results

We found that cylindrical powers, regardless of lens materials, did not have a statistically significant effect on lens thickness (F = 0.30, p = 0.5834) to the limitation of our measurements, while contact lens type, spherical power, location on lens, and axis of cylindrical power were all found to do so. When multi-factor ANOVA was applied to the lens thickness and P2 data, contact lens location had a statistically significant effect on P2 values for both prism-ballasted (F = 640.16, p < 0.0001) and dynamic-stabilized toric lenses (F = 352.85, p < 0.0001). When the same statistical methodology was used to compare the relative performance of all three lenses on P2 during daily wear, the average P2 values for the three different lens brands were all statistically significantly different, while under closed-eye conditions the average P2 values for both silicone hydrogel toric lenses were no longer statistically significantly different (F = 1.00, p = 0.3178).

Conclusion

Assuming that the critical P2 was 100 mmHg, we predicted that silicone hydrogel toric soft lenses would provide reasonable anterior corneal oxygenation, certainly much enhanced over the environment predicted under traditional hydrogel designs, especially during daily (e.g. open eye) wear. Substantial corneal hypoxia continued to be predicted during extended wear of all lenses, but especially so with the use of traditional hydrogels.     

Quarter of a century of contact lens prescribing trends in the United Kingdom (1996 – 2020)

PurposeTo document contact lens prescribing trends in the United Kingdom over the past quarter of a century.MethodsAn annual survey of contact lens prescribing was conducted each year from 1996 to 2020, inclusive, by asking a random selection of optometrists and contact lens opticians to provide information relating to 10 consecutive contact lens fits between January and March.ResultsOver the 25 year survey period, 2,671 practitioners returned survey forms, reporting a total of 25,575 contact lens fits. The mean (± standard deviation) age of lens wearers was 35 ± 15 years, of which 64 % were female. Over the survey period, rigid lens new fits decreased from 22 % to 2%. The prescribing of silicone hydrogel lenses has increased steadily since their introduction towards the end of the 1990s, and now represent 80 % of soft lens fits. Soft toric lens prescribing has gradually increased to 47 % – a value at which astigmatism ≥ 0.75DC is theoretically corrected in all contact lens wearers. Daily disposable prescribing increased steadily over the survey period and now represents 63 % of lenses prescribed. Extended wear fits remain at very low levels, except for some prescribing for overnight orthokeratology. Multi-purpose lens care solutions are ubiquitous; peroxide and other systems are now seldom prescribed. Rigid lenses and monthly replacement soft lenses are predominantly worn on a full time basis, whereas daily disposable soft lenses are mainly worn part time.ConclusionsThis report documents the evolution of contact lens fitting in the United Kingdom over the past 25 years. The most likely lens fit is a spherical design silicone hydrogel daily disposable contact lens prescribed for a 35 year old female and worn on a part-time basis.     

Stabilization of comfort and visual quality after the insertion of soft contact lenses

PurposeTo evaluate comfort, visual function, and in vivo wettability after the insertion of hydrogel and silicone hydrogel contact lenses for a better understanding of how long practitioners should wait for the initial evaluation of soft contact lenses.MethodsA short-term prospective, contralateral, randomized, and participant-masked study was carried out. Twenty healthy participants (25.4 ± 2.6 years) were evaluated after the insertion of two different soft contact lenses at different times (1, 5, 10, 20, 30 min). Ocufilcon D (hydrogel) and Somofilcon A (silicone hydrogel) contact lenses were randomly assigned to both eyes of the same participant. Comfort, visual function under photopic conditions in terms of high-contrast visual acuity, low-contrast visual acuity, contrast sensitivity, and in vivo wettability were measured.ResultsThere was an increase in comfort (p < 0.001), high-contrast visual acuity (p < 0.05), and contrast sensitivity (p < 0.001, only with silicone hydrogel) directly related to time after contact lens insertion. Besides, in vivo wettability suffered a statistically significant deterioration directly related to time with both contact lenses (p < 0.05). Except for comfort and contrast sensitivity, all the parameters stabilized their values 10 min after the insertion of both soft contact lenses. Additionally, in vivo wettability and visual acuity differences were found between hydrogel and silicone hydrogel contact lenses (p < 0.05).ConclusionsIt would be possible to properly evaluate high-contrast visual acuity, low-contrast visual acuity, and in vivo wettability 10 min after the insertion of both soft contact lenses.     

The effect of contact lens wear on dynamic ocular surface temperature.

AIM: To determine the dynamic emitted temperature changes of the anterior eye during and immediately after wearing different materials and modalities of soft contact lenses. METHOD: A dynamic, non-contact infrared camera (Thermo-Tracer TH7102MX, NEC San-ei) was used to record the ocular surface temperature (OST) in 48 subjects (mean age 21.7 +/- 1.9 years) wearing: lotrafilcon-A contact lenses on a daily wear (LDW; n=8) or continuous wear (LCW; n=8) basis; balafilcon-A contact lenses on a daily wear (BDW; n=8) or continuous wear (BCW; n=8) basis; etafilcon-A contact lenses on a daily disposable regimen (EDW; n=8); and no lenses (controls; n=8). OST was measured continuously five times, for 8s after a blink, following a minimum of 2h wear and immediately following lens removal. Absolute temperature, changes in temperature post-blink and the dynamics of temperature changes were calculated. RESULTS: OST immediately following contact lens wear was significantly greater compared to non-lens wearers (37.1 +/- 1.7 degrees C versus 35.0 +/- 1.1 degrees C; p < 0.005), predominantly in the LCW group (38.6 +/- 1.0 degrees C; p < 0.0001). Lens surface temperature was highly correlated (r=0.97) to, but lower than OST (by -0.62 +/- 0.3 degrees C). There was no difference with modality of wear (DW 37.5 +/- 1.6 degrees C versus CW 37.8+/-1.9 degrees C; p=0.63), but significant differences were found between etafilcon A and silicone hydrogel lens materials (35.3 +/- 1.1 degrees C versus 37.5 +/- 1.5 degrees C; p < 0.0005). Ocular surface cooling following a blink was not significantly affected by contact lens wear with (p=0.07) or without (p=0.47) lenses in situ. CONCLUSIONS: Ocular surface temperature is greater with hydrogel and greater still with silicone hydrogel contact lenses in situ, regardless of modality of wear. The effect is likely to be due to the thermal transmission properties of a contact lens.     

Patterns of fitting cosmetically tinted contact lenses

Cosmetically tinted soft contact lenses are an attractive option for contact lens wearers. Data that we have gathered from annual contact lens fitting surveys demonstrate that those wearing tinted lenses are more likely to be female (4.6% of all soft lenses fitted vs. 1.6% for males; p < 0.0001) and younger (27 ± 11 years vs. 33 ± 13 years for those wearing non-tinted lenses; p < 0.0001). Tinted lenses tend to be worn more on a part-time basis and are replaced less frequently than non-tinted lenses. The decline in fitting tinted lenses over the past 12 years may be due to (a) the current limited availability of tinted lenses in silicone hydrogel materials and daily disposable replacement frequencies, which together represent a significant majority (78%) of new soft lenses fits today, (b) growing concerns among lens wearers and practitioners relating to the risks of complications associated with the wearing of tinted lenses, and (c) reduced promotion of such lenses by the contact lens industry.     

Efficacy of spherical aberration correction based on contact lens power

PurposeTo investigate the efficacy of spherical aberration (SA) correction with aspheric contact lenses (aspheric lenses) based on lens power, and compare the results with those of spherical contact lenses (spherical lenses).MethodsOcular higher-order aberrations were measured with a wavefront sensor, in 11 myopic subjects wearing an aspheric lens (Medalist Fresh fit (PUREVISION 2 HD); Bausch + Lomb) or a spherical lens (ACUVUE Oasys; Johnson & Johnson). Six different lens powers (−7.00 diopters (D), −5.00 D, −3.00 D, −1.00 D, +1.00 D, +3.00 D) were used for all subjects. The amount of SA correction from the contact lens at each power was calculated as the difference between SA with the contact lens on-eye and SA of the eye alone.ResultsFor the spherical lenses, SA correction was close to 0.00 μm for the +1.00 D lens, became more positive as the labeled lens power increased and became more negative as the labeled lens power decreased. For the aspheric lenses, SA correction was consistent, from −0.15 to −0.05 μm, for all lens powers except for the −1.00 D lens. SA correction for the spherical and aspheric lenses was significantly different at −7.00 D (p = 0.040), −3.00 D (p = 0.015), −1.00 D (p < 0.001), +1.00 D (p = 0.006), and +3.00 D (p < 0.001) powers.ConclusionAn aspheric lens is capable of correcting SA at different lens powers, and has SA correction in the range of −0.15 to −0.05 μm over a 6 mm aperture.     

Fast versus gradual adaptation of soft monthly contact lenses in neophyte wearers

AimTo determine if a gradual adaptation period is necessary for neophytes when fitted with modern hydrogel or silicone hydrogel reusable disposable contact lenses.MethodAcross four sites, 74 neophytes (18–28 years) were randomly assigned to a reusable lens cleaned nightly with Opti-Free® Puremoist® multi-purpose contact lens solution: Proclear® (hydrogel) or Biofinity® (silicone hydrogel) and an adaptation schedule: fast (10 h wear from the first day) or gradual (4 h on the first day, increasing their wear time by 2 h on each subsequent day until they had reached 10 h). Masked investigators graded ocular surface physiology and non-invasive tear breakup time (NIBUT) and a range of comfort, vision and lens handling subjective ratings (0–100 visual analogue scales) were recorded at the baseline visit and after 10 h of lens wear, 4–6 days and 12–14 days after lens fitting. Subjective scores were also repeated after 7 days.ResultsThere was no difference (p > 0.05) in ocular surface physiology or NIBUT between fast and gradual adaptation groups at any time point in either lens type with the exception of increased corneal staining (p = 0.019) in the silicone hydrogel fast adaptation group after 4–6 days, but was similar by 12–14 days. Subjective scores were also similar across the visits and lens types with the exception of ‘lens awareness’ (p = 0.019) which was less in the gradual versus the fast adaptation silicone hydrogel lens group at 12–14 days.ConclusionThere seems to be no clinical benefit for recommending a gradual adaptation period in new wearers fitted with modern soft reusable disposable contact lenses. The findings of this work add to a growing body of evidence suggesting that such advice is unnecessary in regular soft contact lens wear, which has important ramifications for the initial clinical management of these patients.     

A silicone hydrogel contact lens after 7 years of continuous wear

PurposeTo report an unusual case with a bandage silicone hydrogel lens that was applied over cyanoacrylate glue application for corneal perforation.DesignRetrospective, interventional case report.MethodsA 67-year-old woman with a history of corneal trauma experienced spontaneous corneal perforation in her left eye. Upon arrival, her anterior chamber was flat and Seidel test was positive. After initial treatment with cyanoacrylate adhesive and a bandage silicone hydrogel contact lens, there was no leakage and the anterior chamber was formed at the follow-up period. She was started topical antibiotics.ResultsAfter 7 years, she came back with the complaint of permanent redness in her left eye with the same silicone hydrogel lens in her eye.ConclusionsCorneal healing may occur under cyanoacrylate adhesive glue with therapeutic contact lenses and with proper antibiotic application. Silicone hydrogel contact lenses exhibit good efficacy and safety when utilized as a continuous wear therapeutic lens with antibiotics.     

The efficacy of multifocal soft contact lenses for the alleviation of asthenopic symptoms in myopes with accommodative lag

PurposeTo evaluate the efficacy of multifocal soft contact lenses to reduce asthenopic symptoms in myopes with accommodative lag.MethodsTwenty-four myopic participants, aged 18–35 years, with mean spherical equivalent (MSE) of ≤ -0.75D, were recruited in a randomised, double-blind crossover study. All participants were existing contact lens wearer with near orthophoria or esophoria, presenting with subjective asthenopic symptoms at baseline [Convergence Insufficiency Symptom Survey (CISS) score ≥ 21] and a lag of accommodation ≥ +0.75 D. All participants were initially fitted with single vision contact lenses for a one month period. Participants were then randomly assigned 1:1 to wear low add or high add multifocal soft contact lenses for a further month. After this period, the groups were reversed. Data were collected at baseline and following one month’s wear of each lens. Change in CISS score was evaluated as the primary outcome measure, while secondary outcome measures were changes in accommodative lag and heterophoria status.ResultsBaseline CISS score was (mean ± SD) 25.04 ± 4.58. Post-intervention scores were as follows: single vision: 24.46 ± 4.59, low add: 12.17 ± 6.89, high add: 13.71 ± 7.23. Both low add and high add multifocal soft contact lens wear was associated with an improvement in CISS score compared to baseline CISS and single vision (all p < 0.01). No significant difference was found between the CISS score for the baseline CISS and single vision (p = 1.00). No significant difference was found in lag of accommodation between lens conditions (all p > 0.05), however, there was an exophoric shift in near heterophoria between single vision and both multifocal contact lenses (low add: (mean difference 1.33 Δ, p = 0.02; high add: mean difference 1.23 Δ, p = 0.02) but not between habitual spectacle or any other modality (all p > 0.05).ConclusionsThe use of multifocal soft contact lenses for a one-month period was associated with reduced severity of asthenopic symptoms in pre-presbyopic myopes with accommodative lag. Whilst improvement of symptoms does not appear to be mediated by a significant reduction in accommodative lag, changes in heterophoria may play a role in reducing asthenopic symptoms.     

The effect of tinted soft contact lens wear on functional visual acuity and higher-order aberrations

PurposeTo investigate the differences of functional visual acuity (FVA) and high order aberrations (HOAs) in relation to tinted and clear hydrogel soft contact lens (SCL) wear.MethodsA prospective comparative study was performed in 16 eyes of 16 healthy volunteers. Dynamic visual acuity (using a FVA measurement system) and higher-order aberrations (using a wavefront sensor) were compared in subjects wearing two types of soft contact lenses: 1-day Acuvue^® (Vistakon, Jacksonville, FL) clear and the 1-day Acuvue^® Define^TM (Vistakon, Jacksonville, FL) tinted lens. The blink rates were recorded during FVA testing. The correlation between the difference of HOAs and differences in FVA values was analyzed.ResultsThe mean LogMAR FVA scores with clear and tinted SCLs were 0.07 ± 0.13 and 0.14 ± 0.17 (P < 0.05). The mean blink frequencies with clear and tinted SCL wear were 18.4 ± 8.3 and 25.3 ± 4.7 blinks/min (P < 0.05). Both 3rd-order aberrations and total HOAs showed statistically significant differences between the two types of soft contact lenses for 6 mm pupil measurements (P < 0.05). A significant positive linear correlation was observed between ΔHOAs and ΔLogMAR FVA for 6 mm pupil measurements (R = 0.53, P = 0.04).ConclusionsTinted contact lens wear appears to induce a reduction in optical quality. Functional visual acuity measurement is a useful procedure to study the changes of visual performance and quality in tinted contact lens wear.     

Performance and predictability of a new large diameter contact lens design in keratoconic corneae

ObjectivesTo evaluate the clinical performance and predictability using corneal topography in the fitting of a new large-diameter rigid gas permeable (RGP) contact lens design in eyes with keratoconus (KCN).MethodsThis study presents a review of eyes fitted with Alexa ES lenses for nonsurgical optimisation of visual correction. Anterior steep simulated keratometry (sim-K steep), corneal diameter (HVID), the Curvature at the apex in diopters (Cc), and distance from the corneal apex to the centre of the cornea (Lc) in millimetres derived from the Cone Location and Magnitude Index (CLMI) were recorded. Visual acuity, mean wearing time, final sagittal depth and adverse events were also recorded. Correlations between topographic indices and base curve were evaluated using the Pearson correlation coefficient.ResultsForty-six eyes from 26 patients (19 males/ 7 females) were included. Mean visual acuity improved from 0.49 ± 0.32 with glasses, to -0.02 ± 0.10 with the contact lens. The mean daily wear time was 12.19 ± 1.96 hours. No complications were detected in 95.65% of the eyes [95% CI (83.9%-99.2%)] but two episodes of non-infectious keratitis. The average sagittal depth of the lenses fitted was 0.425 ± 0.15 mm, and it was positively correlated with the Cc value (r² = 0.66, p< 0.0001, n=46) derived from the CLMI index of the pre-fitting topography.ConclusionsCorneoscleral RGP contact lenses are a safe, and effective alternative for managing KCN patients to corneal lenses. Also, clinical data derived from the corneal topography could be used to help to decide the first diagnostic lens to be assessed, easing the overall fitting process.     

Objective evaluation of static and dynamic behavior of different toric silicone-hydrogel contact lenses

PurposeThe present study aimed to estimate how orientation position, recovery time, and contact lens decentration, associated with visual performance, may vary on several designs of the most recent toric silicone-hydrogel toric contact lenses in two-time different moments.MethodsTo evaluate the toric silicone-hydrogel toric contact lens position and stability, it was conducted with a prospective, observational, randomized, and single-center case series including 95 astigmatic eyes wearing four toric silicone-hydrogel toric contact lenses for two weeks. Orientation and decentration were analyzed with ImageJ software from video-frames extracted with a Python application. Recovery time was evaluated after 45 degrees of inferior-temporal misorientation.ResultsEvaluation of misorientation after 20 min of wear revealed the highest amount for Saphir RX, −20.41 ± 10.84 deg, and lowest for Air Optix Aqua for Astigmatism, −1.43 ± 7.48 deg. The highest horizontal misalignment was found for Air Optix Aqua for Astigmatism, −0.627 ± 0.330 mm, and lowest for Biofinity Toric, 0.004 ± 0.270 mm. Vertical misalignment presented the highest value for Acuvue Vita for Astigmatism, −0.652 ± 0.369 mm, and lowest for Air Optix Aqua for Astigmatism, −0.126 ± 0.231 mm. Recovery time showed the highest amount for Saphir RX, 80.70 ± 33.26 s, and lowest for Biofinity Toric 43.67 ± 23.70 s. Only Air Optix Aqua for Astigmatism presented significant differences after two-week of wear for misorientation (P = 0.02) and horizontal misalignment (P < 0.001). When pairwise comparisons are made between toric silicone-hydrogel toric contact lenses, significant differences (P < 0.001) are found.ConclusionsAlthough there was acceptable fitting, based upon decentration, orientation, and recovery with the study contact lenses, the stabilization and profile design used in the Air Optix Aqua for Astigmatism helped to minimize rotation and vertical misalignment. In addition, the peri-ballast and thickness profile of the Biofinity Toric improved rotational recovery and horizontal misalignment compared to the other contact lenses. Finally, lenses with a better fitting profile showed better visual performance.     

Trend of soft contact lens prescribing in an optometry centre in India: A 6-year analysis

This six-year retrospective longitudinal study was conducted to examine the changes in the pattern of prescribing soft contact lenses in an optometry centre located in a University in South India. Details regarding the type of lenses, lens material, wearing pattern and the clinical diagnoses were analyzed from January 2006 to December 2011. A total of 1273 soft contact lens fits (n = 1273) were analyzed. Two-third of the total lenses dispensed was for females and their mean age (24.0 ± 8.3 yrs) was less than that of male (27.0 ± 11.2 yrs) lens users. Nearly 70% of them had myopia and 48% wore conventional soft contact lenses. During the studied six years, the percentage of conventional lenses declined by 60%. This study demonstrated a gradual and significant increase in popularity of disposable contact lenses and silicone hydrogel lens material which is comparable to the global trend.     

Exploring the factors which impact overall satisfaction with single vision contact lenses

PurposeTo explore the impact of subjective factors (lens handling, comfort and vision) on overall single vision contact lens satisfaction.MethodsCorrelation analysis of a prospective, randomised, double-masked, bilateral crossover study involving 55 adapted lens wearers fitted with somofilcon A (SiHy) (clariti® 1 day, CooperVision) and etafilcon A (Hy) (1 DAY ACUVUE® MOIST, Johnson & Johnson Vision) was conducted. Subjective ratings of lens handling, comfort and vision collected after 1 week of lens wear for each lens type were correlated with overall satisfaction. Data were analysed by combining data for both lens types and also for each lens separately.ResultsFor the combined analysis, significant correlations (p < 0.01) were found between subjective ratings of overall satisfaction and ratings of handing for application (r = 0.64), handling for removal (r = 0.50), comfort upon application (r = 0.59), comfort at end of day (r = 0.61), overall satisfaction with comfort (r = 0.88) and overall satisfaction with vision (r = 0.64).Correlation analysis of the per lens data showed that lens specific correlations of overall satisfaction with handling for lens application varied greatly with lens material (SiHy: r = 0.26, p = 0.05 vs Hy: r = 0.72, p < 0.01). Correlation strength of comfort upon application/at end of day with overall satisfaction also varied with lens material (Application: SiHy: r = 0.40 vs Hy: r = 0.61; End of day: SiHy: r = 0.76 vs Hy: r = 0.58; all p ≤ 0.01).ConclusionOverall satisfaction was significantly correlated with the specific subjective evaluations of handling, vision and comfort. Correlations of overall satisfaction and ease of handling for each lens type suggest that, for habitual contact lens wearers, dissatisfaction with handling at the time of lens application can play a major role in overall dissatisfaction with a lens. Handling for application had a similar correlation (r) value as vision, suggesting that handling for application should not be underestimated when considering overall patient satisfaction.     

Uptake and release of polyhexamethylene biguanide (PHMB) from hydrogel and silicone hydrogel contact lenses using a radiolabel methodology

PurposeThe purpose of this study was to evaluate the uptake and release of radiolabelled polyhexamethylene biguanide (PHMB) on reusable daily wear contact lenses (CLs) over 7 days.MethodsThree silicone hydrogel (SH) contact lens materials (lotrafilcon B, balafilcon A, senofilcon A) and two conventional hydrogel (CH) materials (etafilcon A, omafilcon A) were examined. In experiment 1 (1-day study), CLs were soaked in 2 mL of phosphate buffered solution (PBS) containing radiolabelled ¹⁴C PHMB (1 µg/mL) for 8 h. The release kinetics of ¹⁴C PHMB from the CLs was measured at t = 0.25, 0.5, 1, 2, 4, 8, and 24 h in fresh 2 mL PBS. In experiment 2 (7-day study), the CLs were soaked in the ¹⁴C PHMB (1 µg/mL) solution for 8 h followed by a 16-hour release in 2 mL PBS. The lens cycle was repeated daily for 7 days. After both experiments, the residual amount of PHMB remaining within the lenses was extracted to determine the total uptake of PHMB.ResultsIn experiment 1, the total uptake of PHMB for etafilcon A was significantly greater than senofilcon A (p = 0.01). There were no significant differences in total uptake of PHMB between other lens materials (p > 0.05). Etafilcon A released more PHMB compared to all other lens types over a 24-hr period (p < 0.001). In experiment 2, all CL materials continued to sorb more PHMB over time (p < 0.001). By day 7, the amount of PHMB sorbed by etafilcon A was significantly greater than senofilcon A (p = 0.02). After day 2, the CH materials released significantly more PHMB than the SH materials (p < 0.01).ConclusionThe CL materials continued to sorb PHMB with no signs of saturation after 7 days. All lens materials released a consistent amount of PHMB each day. Radioactive labelling provides a sensitive method of assessing the uptake and release of PHMB from CL materials.     

Review of 20 years of soft contact lens wearer ocular physiology data

BackgroundSince the introduction of Silicone hydrogel (SiHy) contact lenses 20 years ago, industry has continued to modify lens materials, designs, lens care products and manufacturing processes, striving to improve contact lens physiological performance, comfort, and convenience for wearers. The purpose of this study was to investigate whether the ocular health of habitual soft contact lens wearers today is better than it was in previous decades.MethodsBaseline ocular physiology data for 3624 participants from a The Brien Holden Vision Institute clinical trials database were retrospectively reviewed. Records were grouped into 3 time periods; A: >2 decades ago (1997–1999), B: one decade ago (2009–2014) and C: recent years (since 2015). Physiology data for both neophytes and habitual contact lens wearers included; bulbar, limbal and upper palpebral conjunctival redness, corneal and conjunctival staining and conjunctival indentation from contact lenses.ResultsCorneal staining levels are similar between neophytes and contact lens wearers at time points A and C but worse for contact lens wearers at time point B. Limbal redness was greater in contact lens wearers than in neophytes at time point A but at time points B and C they are not different to the non-contact lens wearing population. In recent years, most ocular physiological variables in habitual contact lens wearers are similar to neophytes.ConclusionsWhile there have been changes over the past two decades in ocular physiological responses to contact lens wear, it appears that ocular health with current day contact lens wear is similar to no lens wear in most respects.     

An acute clinical comparison of corneal staining and comfort associated with contact lens care solutions

PurposeThis study compared the biocompatibility and comfort of 4 lens care solutions currently marketed in France.MethodsThis was a randomized, interventional, double-masked, single-center crossover study assessing balafilcon A silicone hydrogel contact lenses, bilaterally, straight from the blister pack solution (control) and pre-soaked in the following lens care solutions: Regard^® (containing sodium chlorite), ReNu^® (containing a PHMB [polyhexamethylene biguanide] derivative), CyClean™ and MeniCare™ Soft (both containing PHMB). Subjects were randomized to the order of test solution use. For each of the 5 solutions tested, subjects attended a baseline/lens dispensing visit and an intervention visit 2 h later. At both visits, evaluation included slit-lamp examination, corrected-distance visual acuity, corneal staining, and subject-assessed photophobia, ocular comfort, and ocular redness.ResultsThirty subjects were enrolled and 28 were evaluable. Corneal staining severity was significantly worse than baseline after 2 h of wearing lenses soaked in CyClean, MeniCare, or ReNu (P ≤ 0.001). The MeniCare group alone demonstrated a significant improvement in ocular comfort after 2 h of lens wear (P = 0.02). No group demonstrated significant changes in ocular redness or photophobia. Corrected-distance visual acuity was similar between baseline and intervention visits for each test solution. No adverse events were reported during the study.ConclusionsSilicone hydrogel contact lenses presoaked in lens solutions containing PHMB or a PHMB derivative produced an increase in corneal staining after 2 h of lens wear. The higher levels of corneal staining in the 2 solutions did not correlate with increased discomfort within this 2-h timeframe.     

Exploring non-adherence to contact lens wear schedule: Subjective assessments and patient related factors in children wearing single vision and myopia control contact lenses

PurposeTo determine factors associated with non-adherence to contact lens wear schedule involving single vision and myopia control contact lenses in children.MethodsData from 379 children enrolled in a prospective, double masked, randomized clinical trial, aged 8–13 years, cycloplegic spherical equivalent of -0.75 to -3.50D and wearing either: single vision silicone hydrogel (SiH) CL (control lens); two anti-myopia SiH CL that incorporated relative plus in the central and periphery in a stepped manner (test lens I and II); and two extended depth of focus hydrogel CL (test lens III and IV) was considered. A questionnaire was administered to the participants at every scheduled visit and gathered information on days of wear/week and subjective assessments of ocular comfort and visual quality on an analog scale of 1–10.Participants were categorized as “Adherent” when lens wear was ≥ 6 days/week or “Non-adherent” when lens wear ≤ 5 days/week. Categorized adherence data was summarized as a percentage across visits for each CL type. Differences between the two groups were analyzed using linear mixed model.ResultsFor the control lens, 79.6 % participants were adherent as compared to 63.7%–74.6% with test lenses (p=0.026). Non-adherence was greater in those that discontinued (p<0.001). Subjective ratings of visual quality for static and dynamic tasks were lower with non-adherent wearers and more variable between visits. Ocular comfort was also poorer in non-adherent wearers irrespective of lens material or lens design. Male gender, lower baseline myopia, lower high contrast visual acuity and esophoria were associated with a higher risk of non-adherence.ConclusionsThe study identified a wide range of factors associated with non-adherence to lens wear schedule. Paying specific attention to these factors when evaluating patients for CL wear and taking steps to ensure satisfaction in lens wear may promote longer term continuation of wear.