2010 – Centre for Ocular Research & Education

Scientific Presentations

2020

Chan V, Phan CM, Jones L. Evaluating lysozyme deposition on contemporary daily disposable contact lenses in a novel in vitro blink model The Association for Research in Vision and Ophthalmology, 2020 [ Show Abstract ][ PDF ]

Purpose : To evaluate total lysozyme deposition on daily disposable (DD) contact lenses (CL) using a novel in vitro eye-blink model.

Methods : Three conventional hydrogel (CH) DD CL materials (etafilcon A, omafilcon A, nelfilcon A) and three silicone hydrogel (SH) DD CL materials (delefilcon A, senofilcon A, somofilcon A) were tested. The lenses were removed from their blister packs and placed directly on the eye model. An artificial tear solution (ATS) was flown over the lenses at a flow rate of 1 µl/min. The blink rate was set to 6 blinks per minute and the model was incubated at room temperature (23-26°C) and >45% humidity. After exposure periods of 2, 4 or 8 hours the lenses were removed and the lysozyme was extracted using acetonitrile: 0.2% trifluoroacetic acid (n=3). A separate experiment was conducted with lenses incubated in a vial containing 480 µL of ATS on an orbital shaker at 60 rpm for 8 hours (n=3). The lysozyme activity was measured using a spectrophotometric assay.

Results : Etafilcon A had the highest amount of active lysozyme absorption at all time points (p>0.001). After 8 hours, a cumulative total of 402 ± 102µg/lens of active lysozyme was absorbed on etafilcon A. Delefilcon A had the highest cumulative amount of active lysozyme (26 ± 1µg/lens) for SH materials (p<0.05). Nelfilcon A, senofilcon A and somofilcon A had the lowest amount of lysozyme activity (p<0.05). Overall, CH had a higher amount of lysozyme activity than SH after 8 hours (p>0.05). The amount of active lysozyme sorption for certain lens types was different when measured using the eye-blink model as compared to a vial (p<0.05). Etafilcon A had a higher amount of active lysozyme when incubated on the blink model as compared to the vial (p<0.05), whereas somofilcon A and senofilcon A had a higher amount of lysozyme activity in the vial compared to the eye model (p<0.05). Both methods, however, showed no differences in the amount of active lysozyme sorption for omafilcon A, nelfilcon A, and delefilcon A (p>0.05).

Conclusions : The in vitro eye-blink model provides quantitative data that is close to that determined from ex vivo studies and is an excellent model to assess the deposition of lysozyme on DD CL materials.

This is a 2020 ARVO Annual Meeting abstract.

Cheng X, Almaghshi M, Yang M, Shaw A, Brennan NA. Evaluating on-eye wavefront aberrations of a soft contact lens with an optical design simulating orthokeratology Investigative Ophthalmology & Vision Science 2020;61, 7:554 [ Show Abstract ][ PDF ]

Purpose : Orthokeratology (OK) has been shown to be effective in slowing myopia progression. The mechanism of action is hypothesized to be the resultant optical impact to the eye. However, a soft contact lens (SCL) designed to simulate the optical effect of OK (simOK) for myopia control was found to be ineffective in a randomized controlled myopia control trial. The purpose of this study was to evaluate on-eye wavefront aberrations of the simOK lens by comparing to that of successful OK patients.

Methods : Distance (4 m) and near (25 cm) wavefront aberrations were measured with an open-field Shack-Hartmann aberrometer in 8 OK-treated patients (bare eye only) and 20 non-OK subjects with bare eye (simOK-BE) and with simOK lens on-eye (simOK-LOE) between the age of 7 and 25 years. Zernike expansions of wavefront aberration functions to the 6th order were used to determine aberration coefficients for a series of pupil diameters. Zernike coefficient of primary spherical aberration (Z40), Root-Mean-Square (RMS) of 3rd order and total Higher Order Aberrations (HOA, 3rd – 6th orders) at a 5 mm aperture were compared between simOK-BE and SimOK-LOE and between OK and simOK-LOE. A general linear mixed model with a type I error of 0.05 was used for statistical analysis.

Results : Under a 5mm pupil and with a 4-m target, the means (SD) of Z40 were 0.054 (0.050), 0.350 (0.066), and 0.364 (0.212) microns in simOK-BE, simOK-LOE and OK, respectively. Compared to simOK-BE, Z40 was significantly increased with simOK-LOE with least-square-mean (LSM) difference of 0.297 micron (95% CI: 0.255, 0.338, p<0.001). There was no significant difference in Z40 between simOK-LOE and OK (LSM difference (95%CI): -0.034 micron (-0.148, 0.080), p=0.783). Similar results were found between conditions for near wavefront and for total 3rd order aberrations and total HOAs.

Conclusions : This exploratory study demonstrated that wearing SCL designed to simulate the optical impact of OK resulted in a significant increase of HOAs in the eye. The magnitude of HOAs, including primary spherical aberration and 3rd order aberrations, was similar to those of the OK patients. To fully characterize the on-eye optical performance of the simOK lens and understand the mechanism of action of OK, additional analysis of off-axis refraction and accommodative response with the simOK lens will be examined.

This is a 2020 ARVO Annual Meeting abstract.

Craig J, Bitton E, Dantam J, Ngo W, Jones L. Subjective ocular awareness with the use of eyelid cleansing products available for the management of demodex folliculorum Academy at Home, 2020

Craig J, Jones L, Willcox M, James W, Muntz A, Luensmann D, Tan J, Trave-Huarte S, Wang MTM, Xue AL. Evaluating the therapeutic profiles of lipid and non-lipid based dry eye supplements The Association for Research in Vision and Ophthalmology, 2020 [ Show Abstract ][ PDF ]

Craig J, Muntz A, Luensmann D, Tan J, Jones L, Willcox M, Wolffsohn J. Six-month therapeutic profiles of lipid and non-lipid-based artifical tear supplements in managing dry eye disease Academy at Home, 2020

Guthrie S, Woods J, Vega J, Orsborn G, Ng AY, Jones L. Exploring the factors which impact overall satisfaction with contact lenses Academy at Home, 2020 [ Show Abstract ]

Purpose: To evaluate the performance of two spherical lenses, one silicone hydrogel (SiHy) (somofilcon A) and one hydrogel (Hy) (etafilcon A), using subjective evaluations after 1-week and to correlate the relationships between specific subjective evaluations of lens performance and subjective overall satisfaction.
Methods: Fifty-five subjects participated in a prospective, double-masked, bilateral crossover dispensing study, wearing each lens for 1 week in a randomized order. Subjective ratings (0-10 scale) were completed after 1 week based on a typical day experience and a 4-point Likert scale (Strong/slight preference for each lens) was used to determine lens preference.
Results: Data for both lenses were combined and correlation analyses were conducted. Overall satisfaction was found to be significantly correlated (p<0.01) with handling for insertion (r=0.64), overall satisfaction with vision (r=0.64), handling for removal (r=0.50), comfort at insertion (r=0.59), comfort at end of day (r=0.61) and overall satisfaction with comfort (r=0.88). In addition, insertion comfort was significantly correlated with overall satisfaction with comfort (r=0.66). Considering the lenses separately, SiHy was rated significantly higher for handling for lens insertion compared to Hy (9.4 vs 8.1, p<0.01) and correlation strength with overall satisfaction varied greatly with lens material (SiHy: r=0.26, p=0.05 vs Hy: r=0.72, p<0.01). Overall lens preference based on lens handing for insertion also strongly favoured SiHy (37 subjects vs 18, p<0.01). Comfort at insertion was rated significantly higher at insertion with SiHy (9.0 vs 8.1, p<0.01) and similarly at end of day (8.1 vs 7.9, p=0.80). Correlation strength of comfort at insertion/end of day with overall satisfaction again varied with lens material (Insertion: 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). There were no other statistically significant differences in subjective results for SiHy and Hy.
Conclusions: Significant correlations were found between overall satisfaction and the specific subjective evaluations of handling, vision and comfort. Interestingly, handling for insertion had a similar correlation (r) value as vision, suggesting that handling for insertion should not be underestimated when considering overall patient satisfaction. And while insertion and end of day comfort correlated moderately with overall satisfaction, overall satisfaction with comfort highly correlated with overall satisfaction. Separate analysis of SiHy and Hy also indicate that lower handling and comfort scores for Hy at insertion drove a higher correlation, suggesting that dissatisfaction with both handling for lens insertion and comfort upon lens insertion can play major roles in overall dissatisfaction with a lens.

Luensmann D, Schulze M, Ng AY, Woods J, Jones L. Refitting symptomatic daily disposable contact lens wearers with dry eye disease with delefilcon A lenses Academy at Home, 2020 [ Show Abstract ]

Purpose: To refit symptomatic wearers of daily disposable (DD) contact lenses with a confirmed dry eye diagnosis with Dailies Total1 (delefilcon A, Alcon) to evaluate the performance of the new lenses after one month of wear.
Methods: In this prospective, participant-masked study (over-labelled lenses), symptomatic DD lens wearers were recruited who demonstrated symptoms and signs of dry eye disease according to the TFOS DEWS II criteria. The performance of the lenses after one month was evaluated using subjective ratings and comfort scores, and by determining average wear time and comfortable wear time. Lens wear times as well as subjective symptom scores for comfort, dryness and vision (0-100 scale, with 100 being best) with habitual DD were collected at the screening visit and these results were then compared to delefilcon A after 1 month of wear. The data were not normally distributed, therefore non-parametric analysis (Wilcoxon Matched Pairs Test) was conducted. Data are reported as median (range), with delefilcon A data reported first.
Results: In total, 27 symptomatic DD lens wearers (19 female, 8 male) completed the study. Comfort ratings across all participants were significantly higher (p=0.014) for delefilcon A (80 (40-100)) compared to habitual DD lenses (80 (25-90)). Participants reported less dryness (p=0.007) with delefilcon A compared to their own lenses (80 (40-100) vs 70 (20-95)), and no difference in vision (p>0.05, 90 (50-100) vs (85 (60-100)). There were no statistically significant differences in total hours of lens wear per day (p>0.05, 12.5 hours (6.5-17) vs 11 hours (2.5-16)) or for comfortable wearing time (p>0.05, 8 hours (1-17) vs 6 hours (1-14.8). There were no lens-related ocular findings after one month of delefilcon A wear.
Conclusion: In general, participants had a positive lens wear experience with delefilcon A and rated this lens more comfortable and less dry compared to their habitual DD lenses. This suggests that symptomatic DD lens wearers with dry eye disease may benefit when refit into delefilcon A lenses.

Luensmann D, Woods J, McParland M.. Toric lens fitting success supported by an online fitting App Contact Lens Anterior Eye 2020 [ Show Abstract ][ PDF ]

Purpose: To provide eye care professionals quick access to lens parameter availability and to make soft toric lens fitting easier, online tools are now available to calculate and suggest a first choice prescription based on the patient’s subjective refraction. How close the recommended prescription matches the dispensed lens has been investigated in this study.

Method: In clinical studies, two daily disposable toric lenses, stenfilcon A and somofilcon A, and one monthly replacement toric lens, comfilcon A (all CooperVision, Inc.), were fitted and dispensed to 54, 37 and 47 habitual lens wearers respectively, following the manufacturer’s fitting guides. The final lens prescriptions were determined by the clinician based on over-refraction and lens rotation (Final-Rx). In a secondary analysis the subjective refraction data and back vertex distance were entered in the OptiExpert™ app to determine the recommended initial trial lens (App-Rx). The prescription results from both approaches were compared by calculating the mean differences (Bland-Altman) and the percentages of matching prescriptions following predetermined allowances for sphere, cylinder and axis.

Results: The mean differences between OptiExpert™ and the clinician final prescriptions for sphere, cylinder and axis were within ±0.13DS, ±0.01DC and ±1.38 degrees, respectively. For allowance combination sphere ±0.25D, cylinder ±0.00DC, axis ±10 degrees, the lens prescriptions from both methods matched in 75-82% of eyes (82% stenfilcon A, 75% somofilcon A, 79% comfilcon A). For allowance combination of sph ±0.50D, cyl ±0.00DC, axis ±20 degrees the Final-Rx and the App-Rx matched in 86-92% of eyes (91% stenfilcon A, 92% somofilcon A, 86% comfilcon A).

Conclusions: All three toric lens types showed a predictable on-eye performance, resulting in a close agreement between the initial OptiExpert recommended prescription and the lens prescription dispensed by the clinician. The OptiExpert™ app can therefore confidently be used to assist CooperVision toric lens fitting in order to help optimize patient chair time.

Luensmann D, Woods J, McParland M.. The use of a modern web-application to assist reusable toric lens fitting success Contact Lens Anterior Eye 2020 [ Show Abstract ][ PDF ]

Purpose: Increasing numbers of online tools are available to assist ECPs in fitting contact lenses. In this study, the contact lens prescription of a reusable toric silicone hydrogel lens was determined using a traditional fitting guide and the results were compared to the prescription recommended by the lens fitting app OptiExpert™.

Method: Forty-seven habitual lens wearers were fit with monthly replacement toric silicone hydrogel contact lenses (comfilcon A; CooperVision, Inc.).The manufacturer’s fitting guide was followed and the final lens prescription was determined based on the subjective refraction, the over-refraction and lens rotation (Final-Rx). Following this clinical study, the participant’s subjective refraction data and back vertex distance were entered in the OptiExpert online app to determine the recommended initial trial lens prescription (App-Rx). In this secondary analysis, the fitting results from both approaches were compared using Pearson correlation analysis. Different allowances for sph (±0.25, ±0.50D), cyl (±0.00DC) and axis (±10, ±20degrees) were combined to calculate the percentage of matching fitting results between both methods. Additionally, Bland-Altman graphs were plotted.

Results: A high correlation was found in respect to sphere, cylinder and axis between the Final-Rx and the App-Rx (all r ≥0.88). For the allowance combination of sphere ±0.25D / cylinder ±0.00DC / axis ±10, the lens prescriptions from both methods matched in 79% of eyes. For the allowance combination of sphere ±0.50D / cylinder ±0.00DC / axis ±20, the Final-Rx and the App-Rx matched in 86% of eyes. Bland-Altman comparisons between methods determined a mean difference of +0.06D for sph, +0.01D for cyl and 1.38 degrees for axis.

Conclusions: For most participants, the initial trial lens power recommended by the OptiExpert app was in close agreement to the final power dispensed in the clinical setting. The OptiExpert app can confidently be used as a clinical tool to aid comfilcon A toric lens fitting success.

Nagaarudkumaran N, McCanna D, Ngo W, Jones L. In vitro quantification of cytokines adhered to contemporary contact lens materials The Association for Research in Vision and Ophthalmology, 2020 [ Show Abstract ][ PDF ]

Purpose : Contact lenses (CL) may induce a low-level inflammatory response on the ocular surface. Previous studies have quantified the concentration of inflammatory mediators present in the tear film during CL wear. Analyzing the inflammatory mediators loosely adhered to CL materials may provide another perspective on the role that contact lenses play in inflammation. The purpose of this in vitro study was to quantify a variety of cytokines found in the tear film that adhered to various CL materials and to develop a method that could extract them.

Methods : Cytokines IL-1β, IL-6, IL-8, and TNF-α (Meso Scale Diagnostics, Rockville, MD) were combined with 5 mL of Diluent 2 to prepare a cytokine solution with a final concentration of 119.41, 166.05, 101.48 and 40.73 pg/mL, respectively. Contact lenses (etafilcon A, somofilcon A, omafilcon A, delefilcon A) (n=4 each) were each placed into a polypropylene tube containing a volume of 200 μL of the prepared cytokine solution and were incubated at 23°C for 6 hours. The lenses were removed from the tubes using tweezers and placed into a 0.6 mL microcentrifuge tube containing 200 μL of Diluent 2 and were incubated at 23°C for 1 hour. The microcentrifuge tube was then vortexed for 5 seconds and pin sized holes were made at the base of the tube. The tube was then placed into a larger 2.0 mL microcentrifuge tube acting as a carrier and were centrifuged at 604 RCF. The eluent in the 2.0 mL microcentrifuge was then collected and stored at -80°C for cytokine quantification at a later date, using the MESO QuickPlex SQ 120 (Meso Scale Diagnostics, Rockville, MD). Statistical analysis was performed using a one-way ANOVA.

Results : There was no significant difference between cytokine concentrations for all CL materials (p>0.05).

Conclusions : While there were no significant differences between the concentrations of cytokines found loosely adhered to the soft CL materials investigated, the results support this method as a means to quantify such cytokines on soft lens materials. This method may be used to examine human-worn lenses in future studies.

This is a 2020 ARVO Annual Meeting abstract.

Phan CM, Shukla M, Heynen M, Walther H, Jones L. Development of an In Vitro Blink Model for Measuring Drug and Comfort Agent Elutes from Soft Contact Lens Polymers Academy at Home, 2020 [ Show Abstract ]

Purpose: To develop an advanced in vitro blink model that could be used to examine release of a wide variety of components (topical drugs; comfort agents etc) from soft contact lenses.
Methods: The model was designed using CAD software and 3D printed using an SLA printer. A UV-curable resin polymer was used to fabricate the main components of the eye model to ensure water-sealed parts. The eyelid and eyeball were synthesized from a polyvinyl alcohol and a silicone material respectively. Simulated tear fluid is delivered through tubing attached to the eyelid. With each blink cycle (1 blink/10s), the eyelid slides and flexes across the eyeball to create an artificial tear film. The flow-through fluid is collected in a specialized trough. Two contact lenses, etafilcon A and senofilcon A, were incubated in 2 mL of a water-soluble red dye for 24 hours and then placed on the eye model. The release of the dye was measured at t= 0.5, 1, 2, 4, 8, 12, and 24 hours (n=3) in phosphate buffered saline (flow rate = 5 µL/min). The dye release from the lenses was also evaluated in a vial containing 2 mL of PBS over 24 hours (n=3). The amount of dye in the samples was determined using a UV/Vis spectrophotometer at 520 nm.
Results: All of the contact lenses were visibly red after the incubation with the dye. After the release studies, the etafilcon A lenses became transparent with a slight red tint, whereas the senofilcon A lenses retained a moderate red colour. For the vial study, the release of the dye from the contact lenses was rapid within the first 4 hours, which was then followed by a slower release phase. In contrast, dye release from the lenses on the eye model was significantly slower and was sustained over the 24-hour period. The total amounts of dye released in the eye model were also significantly lower compared to the vial (p<0.05), which could be attributed to the absorption of the dye into the eyelid. From the total amount of tear fluid (7.2 mL) that was infused into the eye model, approximately 5.2 ± 0.6 mL of flow-through was collected. The loss of fluid can be attributed to fluid absorption into the eyelid and contact lenses, as well as evaporation.
Conclusion: The blink model developed in this study could be used to measure the release of topical ophthalmic drugs or comfort agents from contact lenses. The results showed that the release kinetics of a dye from contact lenses on the eye model was significantly different than that of a vial. The model also simulated non-specific absorption of the dye into the eyelid. Future work will focus on developing polymers to simulate the absorption of drugs on the eye.

Schulze M, Ng AY, Luensmann D, Guthrie S, Woods J, Jones L. The subjective response to verofilcon A daily disposable contact lenses during extensive digital device use Academy at Home, 2020 [ Show Abstract ]

Purpose: To evaluate the subjective response of habitual lens wearers during extensive digital device use when switched to Precision1 (verofilcon A) daily disposable (DD) contact lenses (CLs).
Methods: Volunteers between 18-40 years of age who used digital devices for at least 6 hours/day while wearing their habitual CLs were recruited for the study. Eligible participants were dispensed with verofilcon A DD CLs for a period of 2 weeks, during which they were required to wear the study CLs for at least 5 days/week and at least 10 hours/day. Participants returned after 142 days for their final visit, where they reported their CL wear time and time spent using digital devices, and rated their typical experience on a 0 to 100 scale, with 100 being best. Comfort, dryness and clarity of vision with verofilcon A were rated directly after insertion, after 6 hours of digital device use, and just before removal, as well as by rating their overall performance. Participants also completed a 4-point (strongly agree, slightly agree, slightly disagree, strongly disagree) Likert scale-based questionnaire. Subjective ratings were not normally distributed, therefore non-parametric analysis was conducted and data are reported as median (range). The Likert scale responses were analyzed using binomial testing.
Results: Twenty participants completed the study (18F:2M), mean age of 25.1 ± 6.0 years (range 19-40). They reported their typical day to include median CL wear time of 13.8 hours (10.5-17), comfortable CL wear time of 12.1 hours (8-16.5) and digital device use of 9 hours (6-12). After 2 weeks of verofilcon A DD CL wear, subjective ratings after 6 hours of digital device use were high, with ratings for a typical day of 93 (68-100) for comfort, 93 (52-100) for dryness and 96 (70-100) for clarity of vision. After 2 weeks of wear, the majority of participants agreed that the study lenses provided good comfort (16/20 subjects; p=0.01) and good vision (18/20; p<0.01) all day long. Similarly, the majority of participants were satisfied with the comfort (16/20; p=0.01), vision (18/20; p<0.01) and overall performance (16/20; p=0.01) they experienced with the study lenses while using digital devices for 6 hours. Additionally, most reported they did not experience any eye strain while using verofilcon A lenses (n=16/20; p=0.01). No significant lens-related ocular findings were observed after 2 weeks of wear.
Conclusions: After 2 weeks of wear, participants rated the performance of verofilcon A DD CLs very highly, with median overall performance ratings for comfort, dryness and vision all 93 on the 0 to 100 scale (with 100 being best). Verofilcon A DD CLs may be a viable alternative for those struggling with their habitual lens performance when spending long hours using digital devices.

Srinivasan S, Jones L, Schulze M, Guillon M, Tauber J, Silverstein S, Yeu E, Venkiteshwar M. Efficacy of a propylene glycol/hydroxypropyl guar-based lubricant eye drop The Association for Research in Vision and Ophthalmology, 2020 [ Show Abstract ][ PDF ]

Wolffsohn J, Craig JP, Jones L, Trave-Huarte S, Wang MTM. Global approaches to dry eye diagnosis The Association for Research in Vision and Ophthalmology, 2020 [ Show Abstract ][ PDF ]

Abstract
Purpose : Dry eye is a chronic and often debilitating disease, but understanding the prevalence and the effectiveness of management is hampered by differences in diagnosis and subclassification. This cross-sectional survey of eye care practitioners across the world aimed to identify the current approaches to dry eye diagnosis.

Methods : A Survey Monkey questionnaire was developed in consultation with dry eye specialists. Questions sought to determine the tests practitioners consider essential in the diagnosis of dry eye. Which aid the diagnosis? Which aid the subclassification into evaporative or aqueous deficient dry eye? Descriptive statistics were applied.

Results : 1,139 responses were received from 51 countries, 38% from ophthalmologists and 58% from optometrists, with a median of 11-15years of experience. The main tests reported as critical for a diagnosis of dry eye were verbal symptoms (69%), fluorescein breakup time (67%) and corneal staining (64%). In addition, reports of visual disturbance (57%), symptomology results from a validated questionnaire (48%), ocular redness (54%) and blink/lid closure analysis (54%) were commonly used to aid diagnosis. A median of 7 tests were deemed essential to diagnose dry eye (range 0-28). Tests that proved popular for differentiating dry eye subtypes were Schirmer/Phenol red thread test (32%), meibomian gland expression (32%) and orifice examination (32%) and blink/lid closure analysis (32%); use of verbal (38%) and questionnaire (30%) symptomatology, fluorescein breakup time (39%) and corneal staining (37%), for this purpose, were also noted.

Conclusions : In 2018 when the data were collected, dry eye disease diagnosis among practitioners was not standardised and there was little agreement on subclassification to inform the optimal treatment strategy. Future studies will determine whether recent global consensus reports and position papers unify diagnosis of the disease to improve the quality of epidemiological and treatment efficacy data.

This is a 2020 ARVO Annual Meeting abstract.

Wong S, Murphy P, Jones L. Impact of contemporary contact lens wear on tear evaporation measured using a novel evaporimeter The Association for Research in Vision and Ophthalmology, 2020 [ Show Abstract ][ PDF ]

Purpose : To determine whether a novel binocular evaporimeter is able to detect changes in tear evaporation rate (TER) before and while wearing delefilcon A and nesofilcon A contact lenses (CL).

Methods : The evaporimeter consists of a pair of swimming goggles modified with a temperature and relative humidity (RH) sensor embedded in both the right and left goggle lenses. For each measurement, the evaporimeter goggles were positioned and held tightly over the palpebral aperture of both eyes (to ensure an air-tight seal) for 20 seconds. There were two measurement conditions: Open Eye, during which the participants blinked every 3 seconds, and Closed Eye, when the eyes were closed. The difference between the Open and Closed Eye measurements was used to determine the TER from the ocular surface. TER was calculated as the slope of the change in RH in the period 5 to 13 seconds after the evaporimeter was placed over the eyes. Three repeated measurements were taken and averaged together. Two baseline TER measurements were recorded (15-minute interval) prior to CL insertion. Participants were randomized for delefilcon and nesofilcon CL lens wear in either eye. TER was measured after 15 minutes and ≥6 hours of CL wear. Measurements over time and between CL types were compared using repeated measures ANOVA with Bonferroni correction. (Mean±SD: Ambient temperature, 23.2±1.1°C; RH, 43.9±7.7%).

Results : Twenty habitual CL wearers (mean age: 28 years, range 18-71, 95% female) completed the study. Both evaporimeter sensors were able to detect a significant change in TER over time (right: p=0.003, left; p<0.0001). TER was significantly higher after 15 minutes (right: p=0.035, left: p<0.0001) and 6 hours of CL wear (right: p=0.002, left: p=0.001), compared to second baseline measurement. Both CLs showed a significant increase in TER between 15 minutes and 6 hours of lens wear (p=0.001). No significant difference in TER was observed between delefilcon and nesofilcon (p=0.770).

Conclusions : The novel evaporimeter was able to simultaneously measure TER from both eyes. TER significantly increased when CLs were worn and was highest after ≥6 hours of CL wear. No significant differences in TER were found between delefilcon A and nesofilcon A, which suggests that contemporary daily disposable CL materials behave in a similar manner with regards to their impact on TER, regardless of water content or material.

This is a 2020 ARVO Annual Meeting abstract.

Woods J, Guthrie S, Varikooty J, Jones L. Satisfaction of habitual wearers of reusable multifocal lenses when refitted with a daily disposable, silicone hydrogel multifocal lens Contact Lens Anterior Eye 2020 [ Show Abstract ][ PDF ]

Purpose: Visual performance with multifocal contact lenses (MFCL) can vary with lens design. This study simulated a real-world refit of habitual wearers of reusable MFCL with a silicone hydrogel (somofilcon A), daily disposable multifocal (DDMF) lens to assess visual and overall experience with the new design and modality.

Method: Subjects rated the DDMF and compared it with their habitual reusable MFCL. The habitual MFCL prescription was not reviewed or confirmed as optimal, though all reported having an eye-examination within 2-years. Subjects were masked to the DDMF brand. After 2 weeks of daily wear with the new lens, subjects reported their experience using 0-10 ratings and Likert scales.

Results: Twenty-eight subjects, spanning 14 habitual lens brands, completed the study. Visual acuity with DDMF was statistically better than with habitual MFCL for all four distances measured (all p<0.05); distance (≥6m): -0.040.09, long intermediate (1.5m): -0.110.11, short intermediate (0.75m): -0.100.09, and near (0.4m): 0.020.09. Subjective vision clarity was statistically better with the DDMF for distance tasks in the dark, long intermediate tasks, and when considering all visual needs (all p<0.05). There were no statistical differences (all p>0.05) for vision clarity performing tasks at distance, short intermediate and near. When asked for a preference, the DDMF was significantly preferred over habitual for long intermediate tasks (p=0.03), but not different for tasks at other distances. Ease of insertion was statistically better with the DDMF (p=0.03); ease of removal was not different. End of day comfort was not different from the habitual lenses (p=0.10), however the DDMF was rated better for end-of-day dryness (p=0.01) and overall satisfaction with lenses (p=0.04).

Conclusions: This daily disposable, silicone hydrogel (somofilcon A), multifocal lens provided good vision and overall performance. Many ratings showed it to provide statistically better performance than their habitual reusable MFCL, supporting the benefits of a trial wear period.

Yee A, Phan CM, Heynen M, Walther H, Jones L. The uptake and release kinetics of myristamidopropyl dimethylamine (MAP-D) from contact lenses using radioactive labelling he Association for Research in Vision and Ophthalmology, 2020 [ Show Abstract ][ PDF ]

Purpose : Biocides are an important disinfecting component commonly found in contact lens (CL) multipurpose solutions (MPS). During the disinfection step, the uptake of biocides into CL materials can significantly reduce the efficacy of the MPS to disinfect the lens. An increased release of biocides from the CL can lead to clinical complications such as discomfort and corneal staining. However, detection methods using chromatography and spectrometry can be time-consuming and have low sensitivity. The purpose of this study was to evaluate the uptake and release of myristamidopropyl dimethylamine (MAP-D; ALDOX®) using a radiolabel method.

Methods : Radioactive (14C) MAP-D was purchased from Moravek Inc. (CA, USA). Five soft CL materials (lotrafilcon B, balafilcon A, senofilcon A, etafilcon A, omafilcon A) were tested (N=4). The lenses were incubated in PBS (ISO 18369-3) solution containing 2mL of 14C radioactive MAP-D (5µg/mL) for 8 hours, followed by a release period in PBS for 16 hours. The cycle was continued over a 7-day period with a new replenishing solution for each day. The samples were counted for their radioactive signal (CPM) using the LS6500 Beckman Coulter liquid scintillation beta counter (ON, CA). A standard curve was used to convert CPM to µg of MAP-D.

Results : After 7-days, the silicone hydrogel (SH) lenses, lotrafilcon B (36.21±0.42µg), balafilcon A (36.29±1.15µg) and senofilcon A (35.54±1.37µg) had a significantly greater uptake of MAP-D compared to the conventional hydrogel (CH) lenses, etafilcon A (7.66±1.19µg) and omafilcon A (6.54±0.94µg) (p<0.01). However, the percent of MAP-D released was higher for CH lenses, etafilcon A (80%), omafilcon A (93%) compared to SH lenses, lotrafilcon B (25%), balafilcon A (19%) and senofilcon A (19%) over the 7-days (p<0.01).

Conclusions : Radioactive labelling offers a highly sensitive and accurate way of assessing the uptake and release kinetics of MAP-D to CL materials. Greater uptake of MAP-D occurs to SH materials, and the release of MAP-D is relatively minor. While CH materials take up only low amounts of MAP-D, the majority of it is easily released from these materials.

This is a 2020 ARVO Annual Meeting abstract.