The use of daily disposable lenses in problematic reusable contact lens wearers

Comfort After Refitting Symptomatic Habitual Reusable Toric Lens Wearers with a New Daily Disposable Contact Lens for Astigmatism

Purpose

To subjectively evaluate comfort with a daily disposable (delefilcon A for astigmatism) contact lens compared to other common weekly/monthly soft toric contact lenses in symptomatic wearers.

Methods

This open-label, single arm study enrolled current reusable soft toric lens wearers with minimum score of 12 on the contact lens dry eye (CLDEQ-8) questionnaire. Subjects were also administered the CLDEQ-8 after 1 replacement schedule of their optimized habitual toric lenses (2 to 4 weeks), and after 2 weeks of wear with delefilcon A toric daily disposable lenses (Dailies Total1 for Astigmatism; Alcon Vision LLC, Fort Worth, Texas).

Results

A total of 85 subjects completed the study. Mean total CLDEQ-8 score was 16.8 ± 8.1 for subjects refit with their optimized habitual toric lenses and 12.4 ± 7.5 for subjects refit with delefilcon A toric lenses, a difference of 4.3 ± 10.4 (p < 0.001). With delefilcon A toric lenses, 78.9% of subjects reported little to no intensity of eye discomfort, compared to 51.7% for the habitual toric lenses (p = 0.005). In addition, 77.7% of subjects reported little to no intensity of dryness for delefilcon A toric lenses, compared to 50.6% for the habitual toric lenses (p = 0.001).

Conclusion

The subjective comfort in symptomatic habitual reusable toric contact lens wearers was improved by refitting with delefilcon A toric lenses.

TFOS Lifestyle: Impact of contact lenses on the ocular surface

Several lifestyle choices made by contact lens wearers can have adverse consequences on ocular health. These include being non-adherent to contact lens care, sleeping in lenses, ill-advised purchasing options, not seeing an eyecare professional for regular aftercare visits, wearing lenses when feeling unwell, wearing lenses too soon after various forms of ophthalmic surgery, and wearing lenses when engaged in risky behaviors (e.g., when using tobacco, alcohol or recreational drugs). Those with a pre-existing compromised ocular surface may find that contact lens wear exacerbates ocular disease morbidity. Conversely, contact lenses may have various therapeutic benefits. The coronavirus disease-2019 (COVID-19) pandemic impinged upon the lifestyle of contact lens wearers, introducing challenges such as mask-associated dry eye, contact lens discomfort with increased use of digital devices, inadvertent exposure to hand sanitizers, and reduced use of lenses. Wearing contact lenses in challenging environments, such as in the presence of dust and noxious chemicals, or where there is the possibility of ocular trauma (e.g., sport or working with tools) can be problematic, although in some instances lenses can be protective. Contact lenses can be worn for sport, theatre, at high altitude, driving at night, in the military and in space, and special considerations are required when prescribing in such situations to ensure successful outcomes. A systematic review and meta-analysis, incorporated within the review, identified that the influence of lifestyle factors on soft contact lens dropout remains poorly understood, and is an area in need of further research. Overall, this report investigated lifestyle-related choices made by clinicians and contact lens wearers and discovered that when appropriate lifestyle choices are made, contact lens wear can enhance the quality of life of wearers.

Evaluation of Wear Experience with Soft Daily Disposable Lenses for Astigmatism over 16 Hours of Wear

OBJECTIVE

The purpose of this study was to assess the wear experience of participants while wearing a toric daily disposable contact lens with water surface technology over long days of lens wear.

METHODS

Existing soft toric contact lens wearers were fit with the daily disposable study lenses. Participants assessed their initial comfort, vision, and satisfaction with the lenses by visual analog scale (VAS) survey. After a successful 1-week follow-up visit, participants were scheduled for 5 survey days, in which surveys were deployed to their smartphones for immediate assessments of comfort and quality of vision on a 1-10 scale at 10, 12, 14, and 16 hours of lens wear on 5 subsequent weeknights. The final study visit assessed visual acuity, and overall lens wear experience surveys were completed with VAS surveys. The overall median and interquartile (IQR) range of all surveys were calculated.

RESULTS

Thirty bilateral toric lens wearers completed the study. Median (IQR) initial impression VAS scores were 97(12) for quality of vision, 100(9) for comfort, and 96(10) for satisfaction. Median evening surveys resulted in comfort scores of 10(1) at 10 hours, 9(2) at 12 hours, 9(2) at 14 hours, and 8(2) at 16 hours of wear. Median evening surveys resulted in quality of vision scores of 10(1) at 10 hours, 10(2) at 12 hours, 9(2) at 14 hours, and 9(3) at 16 hours of wear. VAS scores for overall experience were 97(9) for comfort, 95(13) for vision, and 8(31) for dryness. End-of-day VAS scores were 93(21) for comfort, 90(15) for vision, and 21(38) for dryness. Mean (±standard deviation) OU LogMAR visual acuity with the study lenses was -0.19(0.06).

CONCLUSION

Surveys of wear experience resulted in high scores for comfort and vision over the course of a long day of wear with the daily disposable study lenses in this population of patients with astigmatism.

Long Day Wear Experience with Water Surface Daily Disposable Contact Lenses

OBJECTIVE

The purpose of this study was to assess the wear experience of silicone hydrogel daily disposable contact lenses with water surface technology over a long day of lens wear.

METHODS

Thirty-five soft contact lens wearers were refit with the daily disposable study lenses and participants scored their initial impressions of comfort, vision and satisfaction using a visual analog scale (VAS). Participants used their smart phones to complete surveys of comfort and vision on a scale of 1-10 at 10, 12, 14, and 16 hours of lens wear on 5 weeknights. A participant score for each time point was calculated by averaging the evening responses. End of study VAS surveys of symptoms were also completed.

RESULTS

Median (Interquartile Range) VAS initial impression scores were 99.00 (12.00) for quality of vision, 98.00 (16.00) for comfort, and 100.00 (13.00) for satisfaction. The end of study surveys found end of day median VAS scores of 87.00 (19.00) for end of day quality of vision and 75.00 (24.50) for end of day comfort. The median score for overall quality of vision was 93.00 (14.00) and for overall comfort was 93.00 (16.50). The median score for end of day dryness was 37.00 (55.00) and overall dryness was 13.00 (34.00).

CONCLUSION

The daily disposable lenses with water surface treatment used in this study maintained high median scores for comfort and quality of vision for up to 16 hours of wear.

Wear Experience of a Water Surface Daily Disposable Contact Lens in Existing Silicone Hydrogel Planned Replacement Lens Wearers

PURPOSE

The health benefits of silicone hydrogel lens materials and a daily replacement modality have been demonstrated in previous studies; however, existing planned replacement lens wearers may resist changing to a new lens replacement schedule. The purpose of this study is to evaluate the wear experience of satisfied planned replacement silicone hydrogel wearers when refit into a silicone hydrogel daily disposable lens.

PATIENTS AND METHODS

In this open-label, non-comparison study, satisfied wearers of two week planned replacement contact lenses were evaluated for inclusion criteria and refit with optimized prescriptions in their habitual lenses. At a follow-up visit one week later, participants were refit with the study daily disposable lenses and completed visual analog scale (VAS) surveys of initial quality of vision, comfort, and satisfaction. Participants returned for a final visit after two weeks of wearing the study daily disposable lenses. At the final visit, VAS surveys for both overall and end of day (EOD) vision, comfort, and dryness were completed. Overall median and interquartile range (IQR) were assessed for all surveys in the study.

RESULTS

Thirty individuals completed the study (29.1 ± 7.8 years old; 19 female). Median (IQR) results for the initial impression VAS surveys were 92.50(11.75) for quality of vision, 92.50(18.00) for comfort, and 93.00(18.00) for satisfaction. Final VAS survey results revealed median scores of 87.50(25.00) for EOD quality of vision and 82.50(51.25) for EOD comfort. The median overall quality of vision was 91.00(17.00) and overall comfort was 93.00(28.50). Median (IQR) overall dryness was 28.50(49.00) and median EOD dryness was 30.50(64.25).

CONCLUSION

The findings of this study suggest that providers can successfully refit satisfied wearers of early generation silicone hydrogel planned replacement lenses into a new generation silicone hydrogel daily disposable lens while maintaining satisfaction.

Could contact lens dryness discomfort symptoms sometimes have a neuropathic basis?

Symptoms of dryness discomfort in soft contact lens wearers frequently lead to discontinuation from wear. The negative influence of pre-fitting tear dysfunctions appears likely to be exacerbated by the challenges to tear homeostasis caused by contact lenses. The corneal mechanisms for symptoms in contact lens wearers are different to those for dry eye disease because the cornea is insulated by the lens from ambient conditions as well as from lid wiper friction during blinking. Symptoms of dryness discomfort might be the consequence of increased lid wiper friction during blinking when the lens front surface becomes soiled and dry and exhibits very rapid tear break up. It is possible that some cases of contact lens intolerance and discontinuation could be a function of lid wiper neuropathy. In relation to the possibility of corneal neuropathy, a stagnant post-lens tear pool with the possibility of increased concentrations of metabolic by-products, cellular debris, and bacterial exotoxins, might have the potential to disturb the corneal epithelial and sub-basal nerves. Contributions by contact lens-induced inflammation to any neuropathic changes may partly depend on the degree to which inflammatory mediators are concentrated in a stagnant post-lens tear pool. It does not appear to be known if corneal neuropathic changes could develop under these conditions. The chances of neuropathic involvement may be greater if discomfort develops after a significant period of successful wear and there is a history of comorbid pain conditions. Esthesiometry and in vivo confocal microscopy in discontinued contact lens wearers may support a diagnosis of contact lens-related corneal neuralgia.

A Review of Contact Lens Dropout

PURPOSE

Contact lens (CL) dropout is likely a major factor contributing to the near stagnant growth in the CL market. The purpose of this review is to summarize the current state of knowledge related to the frequency of CL dropout and the factors associated with it.

METHODS

PubMed.gov was searched on or before March 22, 2020, with the terms "contact lens" with "dropout" or "cessation" or "disruption" or "discomfort". Pertinent articles were collected. The references from these articles were likewise searched to identify additional relevant articles. Only manuscripts written in English were included. No study design or date exclusions were imposed on this review.

RESULTS

This literature review found that CL dropout was frequent across developed countries, with a CL dropout frequency that ranged between 12.0% and 27.4% (pooled mean = 21.7%). The top cited reason for CL dropout in established CL wearers was discomfort, while vision was the top reason in neophyte CL wearers. If given the chance, CL dropouts are often able to successfully resume CL wear up to 74% of the time. While the literature is mixed with regard to factors promoting CL dropout, meibomian gland dysfunction appears to promote CL dropout.

CONCLUSION

CL dropout is a frequently encountered condition that may be curtailed by early detection, patient education, alterative CL options, or early treatment of underlying ocular surface diseases such as meibomian gland dysfunction.

Thirty years of 'quiet eye' with etafilcon A contact lenses

Frequent replacement contact lenses made from the etafilcon A hydrogel lens material were introduced onto the market over 30 years ago, and etafilcon A remains the most widely used hydrogel lens material today. Although the prescribing of silicone hydrogel lenses is increasing, millions of lens wearers globally have been wearing hydrogel lenses for many years and exhibit a physiologically-stable 'quiet eye', with a low profile of adverse events. Hydrogel lenses are demonstrated to maintain a low inflammatory response and infection risk profile during daily wear, which in the case of etafilcon A, may be related to its low modulus, and the naturally-protective, anti-microbial, non-denatured lysozyme absorbed into the lens from the tear fluid. Although improved corneal physiology from decreased hypoxia with silicone hydrogel lenses is well accepted, equivalent levels of corneal oxygenation are maintained during daily wear of low to medium powered hydrogel lenses, which do not impede the daily corneal de-swelling process, and do not induce clinically significant changes in ocular health. Therefore, hydrogel lenses remain an important alternative for daily wear in modern contact lens practice.

A 12-month Prospective Study of Tear Osmolarity in Contact Lens Wearers Refitted with Daily Disposable Soft Contact Lenses

SIGNIFICANCE

Tear osmolarity has been reported as one of the best diagnostic tests for dry eye disease and its management. Contact lens wear is thought to influence tear homeostasis. Understanding how regular wear of contact lenses and their type affect tear osmolarity is important.

PURPOSE

The purpose of this study was to assess changes in tear osmolarity and ocular symptoms over a period of 12 months following refitting contact lens wearers with daily disposable contact lenses.

METHODS

Fifty subjects aged (mean ± SD) 26 ± 4 years were refitted with either silicone-hydrogel (delefilcon A, SiHy, n = 34) or hydrogel (omafilcon A, Hy, n = 16) daily disposable soft contact lenses. Study included seven visits: baseline measurements without contact lenses; two visits for contact lens fit and selection; follow-up measurements after 3, 6, and 12 months of contact lens wear; and a post-study visit without contact lenses. Lens type selection was based on a set of objective measurements. Subjects were instructed to follow strict wearing rules. Impedance-based osmometer was used to collect samples from the lower tear meniscuses. The Ocular Surface Disease Index (OSDI) and the eight-item Contact Lens Dry Eye Questionnaire were used to assess subject-reported ocular symptoms and contact lens discomfort, respectively.

RESULTS

Downward trend of tear osmolarity was noted over the time course of study. Statistically significant differences were noted in tear osmolarity (Friedman test, χ = 21.91 [P < .001], and χ = 13.89 [P = .003]) for the right and left eyes, respectively. A statistically significant decrease in tear osmolarity was apparent only for initially symptomatic subjects (for OSDI ≥13: χ = 26.25, P < .001; for OSDI <13: χ = 5.65, P = .13). Statistically significant differences were not noted in OSDI and the eight-item Contact Lens Dry Eye Questionnaire between the baseline and 12-month visit (χ = 5.92 [P = .12] and R = 0.015 [P = .87], respectively). There was a difference between baseline and post-study visits (P = .002) in OSDI, showing lower score at the latter visit.

CONCLUSIONS

Refitting with daily disposable contact lenses was demonstrated to lower tear osmolarity.

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.

A study of contact lens compliance in a non-clinical setting

PURPOSE

To evaluate soft contact lens replacement, overnight (ON) wear, and contact lens case compliance in a non-clinical sample.

METHODS

Subjects (n = 297) were recruited at the Center for Science and Industry (COSI) in Columbus, Ohio. Adult (≥ 18 years) soft contact lens wearers completed a survey about contact lens replacement, ON contact lens wear, and contact lens case replacement habits.

RESULTS

Two-week replacement lenses (according to the manufacturer's replacement schedule [MRS]) were most common (45.5%), followed by monthly (34.3%) and daily replacement (20.2%). Non-compliance with replacement schedule was reported in 38.7% of subjects. Age (p = 0.02), years of lens wear (p = 0.02), and MRS (p <0.0001) affected replacement compliance. Post-hoc analysis showed daily replacement wearers were more compliant than two-week (p <0.0001) and monthly (p <0.0001) replacement wearers with prescribed lens replacement. Non-compliance with prescribed ON wear was reported in 23.9% of subjects. Subjects who were non-compliant with lens replacement were more likely to be non-compliant with ON wear (p = 0.02) and had worn contact lenses for less time (p = 0.02). Of the subjects who used contact lens cases, 74.6% were unsure when they should replace their case. Frequency of case replacement was not associated with age (p = 0.5), gender (p = 0.5), years of contact lens wear (p = 0.7), MRS (p = 0.4), replacement compliance (p = 0.3), or ON wear compliance (p = 0.7).

CONCLUSIONS

Daily replacement wearers were most likely to be compliant with contact lens replacement, but all subjects, including daily replacement wearers, had similar ON wear non-compliance. Non-compliant lens replacement was associated with non-compliant ON wear, but contact lens case replacement was not related to either compliance category. The majority of subjects had no knowledge of proper contact lens case replacement, despite compliance in other categories.

The short-term physiological impact of switching reusable silicone hydrogel wearers into a hydrogel daily disposable multifocal

Purpose: To evaluate ocular physiological responses to etafilcon A multifocal (etMF) daily disposable (DD) lenses after 4 weeks of wear, when switching from habitual silicone hydrogel (SiHy) daily wear.

Method: A single-arm, open-label, bilateral dispensing study was conducted in 39 habitual spherical SiHy wearers (14 hyperopes; 25 myopes). Clinical visits occurred with habitual SiHy (control) at baseline and after 4 weeks of etMF DD open-eye lens wear at exit. Objective limbal/bulbar hyperemia using the Oculus K5M (0–4) and subjective grading of lid wiper epitheliopathy (LWE) (0–4) were tested for non-inferiority (NI), using a margin of 1 grade. Corneal thickness along a 10 mm cord was measured using the Visante OCT and tested for NI using a 30 μm margin. Corneal staining area was graded (0–100%).

Results: The least-square mean differences (LSMD) and 95% confidence interval (95% CI) between etMF DD and habitual SiHy in central and peripheral corneal thickness (μm) were 3.64 (−2.0, 9.29) and 3.0 (−7.72, 13.72) in hyperopic, and 3.56 (−0.66, 7.78) and 6.40 (−1.62, 14.42) in myopic subjects. The LSMD (95% CI) for bulbar and limbal hyperemia were −0.08 (−0.19, 0.02) and −0.01 (−0.12, 0.09) in hyperopes, and 0.04 (−0.03, 0.12) and 0.04 (−0.04, 0.11) in myopes. The LSMD (95% CI) for LWE were 0.11 (−0.39, 0.60) and 0.30 (−0.07, 0.67) for hyperopes and myopes, respectively.

Conclusions: No clinically significant differences in a variety of physiological responses were found when habitual reusable SiHy daily wear subjects were refitted into hydrogel etMF, when the subjects were followed for 4 weeks.

Eye care professionals' perceptions of the benefits of daily disposable silicone hydrogel contact lenses

PURPOSE

To gain a better understanding of eye care professionals' (ECPs) perceptions regarding the benefits of silicone hydrogel (SiH) daily disposable contact lenses (DDCL), particularly with respect to health, comfort and patient satisfaction.

METHODS

A survey was conducted with 300 ECPs in the United States, United Kingdom and Japan during November 2017. The survey comprised 34 statements relating to SiH DDCLs, to which the ECPs provided their level of agreement using a 6 point Likert scale. A minimum of 70% agreement was set to define majority agreement. Categories of statements included Health, Comfort, Patient Experience, and Standard of Care.

RESULTS

ECPs rated the highest levels of agreement to perceptions within the Patient Experiences and Health categories. The six statements receiving the highest ratings were "Silicone hydrogel 1 day lenses satisfy today's patients' demanding lifestyles" (93% agreement); "Silicone hydrogel 1 day lenses are the best choice to safeguard my patients' eye health related to contact lens wear" (92%); "Silicone hydrogel 1 day lenses provide the best benefits to my patients" (92%); "Silicone hydrogel 1 day lenses provide better long term eye health for my patients than hydrogel 1 day lenses" (91%); "Silicone hydrogel is the healthiest lens material for my daily disposable patients" (90%); and "Silicone hydrogel 1 day lenses provide a better wearing experience for my patients than hydrogel 1 day lenses" (90%).

CONCLUSION

ECPs perceive that SiH DDCLs offer long-term eye health
and comfort for the patient and although the ECPs surveyed would not necessarily prescribe SiH DDCLs to all their patients, they would prescribe them to most of their patients. The results support the premise that while ECPs consider SiH 1 day contact lenses as the current "standard of care"; the principal barrier continues to be the perceived higher cost of these lenses.

Comparison of Silicone Hydrogel and Hydrogel Daily Disposable Contact Lenses

OBJECTIVE

To compare subjective, objective and safety performance of silicone hydrogel (SiHy) daily disposable (DD) with hydrogel (Hy) DD contact lenses.

METHOD

Retrospective analysis on approximately 40 participants (Px) each in 5 trials. Lenses grouped into SiHy (delefilcon A, somofilcon A, narafilcon A) and Hy (omafilcon A, nelfilcon A). Participants attended follow-up visits at baseline, 2 weeks, 1 and 3 months. Subjective ratings (1-10 scale), adverse events (percentage of Px), physiological variables (0-4 scale), and wearing time were collected at each visit and compared between groups.

RESULT

Trials enrolled 201 Px totally. No differences in age, sex, and lens wear experience were found between SiHy and Hy groups (P≥0.09). There was greater increase in limbal redness from baseline in Hy group (0.18±0.38 vs. 0.02±0.47, P<0.001), whereas conjunctival staining and indentation were less in Hy group (P<0.001). No differences in comfortable wearing time were found between groups (P=0.41), and comfort at insertion, during day, and end of day was also no different (P≥0.71). Incidence of corneal infiltrative events (SiHy vs. Hy: 6.7% vs. 2.5%; P=0.32) and mechanical adverse events (SiHy vs. Hy: 0.0% vs. 0.0%; P=1.00) were no different.

CONCLUSION

Though some statistical significance was found between the groups, these differences were within measurement error. Neither material types showed superiority in comfort, and adverse event rates were low with both material types. These findings suggest that choice of material is a patient and practitioner preference; however, for patients at risk of hypoxia-related complications, SiHy materials should be considered.

Reliability of Blotting Techniques to Assess Contact Lens Water Content

OBJECTIVES

To determine the reliability of wet and modified dry blotting techniques used in the gravimetric method to assess contact lens (CL) water content (WC), the accuracy of both techniques in comparison with the nominal WC, and also their agreement.

METHODS

We evaluated hydrated and dry CL mass values and WC using the gravimetric method in 440 daily disposable CLs. Samples assessed corresponded to Dailies Total 1, Dailies AquaComfort Plus, 1-Day Acuvue TruEye, and Biotrue ONEday. Back vertex power ranged from +3.00 diopters (D) to -6.00 D. Within-subject coefficient of variation (CVw) and intraclass correlation coefficients were calculated. Bland-Altman analysis was also performed.

RESULTS

The modified dry blotting technique yielded significantly (P≤0.0001) higher hydrated CL mass values. The wet blotting technique provided significantly (P≤0.04) better consistency than the modified dry one. Values of CVw for wet and modified dry blotting techniques ranged from 1.2% to 2.1% and from 3.7% to 5.4%, respectively. As for dry CL mass values, CVw values were not significantly different (P≥0.05) between wet (range: 1.1%-1.9%) and dry (range: 1.0%-5.1%) blotting techniques, except for Dailies AquaComfort Plus (P=0.03). Bland-Altman analysis showed poor agreement between the techniques. The wet blotting technique yielded WC values close (around 1%) to nominal ones, in contrast to modified dry blotting technique (≥2.5%).

CONCLUSIONS

The wet blotting technique is not only more reliable than the modified dry one when obtaining hydrated CL mass but also provides more accurate nominal WC measurements. Agreement between the techniques was poor.

Subjective Ratings and Satisfaction in Contact Lens Wear

SIGNIFICANCE

This study shows satisfaction in contact lens (CL) wear is influenced by both comfort and vision. Eighty-six percent of participants were willing to continue with trial CL wear if satisfied with both comfort and vision, dropping to 50% if either variable was unsatisfactory and 0% if both were unsatisfactory.

PURPOSE

The aim of this study was to understand the relationship between subjective ratings and satisfaction with CL wear.

METHODS

This was a retrospective analysis of two daily-disposable CL trials (delefilcon A, somofilcon A) on participants 40 years or younger followed over 3 months. Subjective ratings (numerical rating scale 1 to 10, 1-point step) collected at visits following baseline (2 weeks, 1 and 3 months) included comfort (insertion, during day, end of day), vision clarity, and binary response for satisfaction with comfort and vision (yes/no). Willingness to continue with trial CL was obtained at completion.

RESULTS

There was no significant association of comfort on insertion with comfort satisfaction (odds ratio [OR], 1.2; P = .30); however, comfort during day (OR, 2.1; P < .001) and end of day (OR, 3.4; P < .001) was associated with comfort satisfaction. For comfort during day ratings of at least 8/10 and end of day of at least 6/10, 90% of participants were considered satisfied. There was a 14% increase in participants satisfied with comfort for each unit increase on the numerical rating scale from ratings of 3 to 8 for comfort during day and a 20% increase from ratings of 3 to 7 for comfort end of day. The percentage of satisfied participants reached its maximum at a lower end of day rating (8/10) compared with during day (10/10). The percentage of participants satisfied with vision reached its maximum (100%) at a vision rating of 9/10.

CONCLUSIONS

Satisfaction in CL wear is influenced by both comfort and vision. A higher rating for comfort during the day compared with end of day is necessary for participants to attain satisfaction.

Raman imaging of layered soft contact lenses

BACKGROUND

Daily disposable contact lenses are gaining in popularity among practitioners and wearers for the improved ocular health and subjective outcomes they offer. Recently a novel daily disposable contact lens material with water gradient technology was introduced. Delefilcon A lenses consist of a 33% water content silicone hydrogel core and an outer hydrogel layer which is totally free of silicone and contains 80% water.

METHODS

The aim of the present study was to confirm the layered structure of delefilcon A contact lenses. Thickness of hydrogel coating on the silicone hydrogel core was assessed using Raman spectroscopy. To investigate the layered structure of the material, depth spectra of the lenses were recorded.

RESULTS

The results obtained suggest that at about 6 μm a boundary between the hydrogel layer and silicone hydrogel core exists, which is in good agreement with the manufacturer's data.

CONCLUSIONS

Data collected in this experiment confirm a water gradient at the delefilcon A lens surface.