<p>Subjective Comparison of Pre-Lens Tear Film Stability of Daily Disposable Contact Lenses Using Ring Mire Projection</p>

Abstract

Purpose: To subjectively evaluate the in vivo tear film stability of three daily disposable contact lenses (DDCLs) using placido ring reflection at lens wear times of 5 mins and 8 and 12 hrs. Patients and Methods: This prospective, randomized, observer-masked, 3-way crossover study evaluated 28 subjects with good tear film stability. In vivo tear film stability was assessed for three DDCLs (nelfilcon A, etafilcon A, omafilcon A) on three different days over 12 hrs of lens wear. Time to first distortion by non-invasive keratography drying-up time (NIK-DUT f) was assessed by reviewing the captured videos. Lens wettability was also graded subjectively by three investigators using a scale from 0 (no visible distortions) to 3 (distortions in more than one-third of the ring reflection zone). Medians were analyzed statistically. Results: Mean NIKDUT f at 8 hrs was longer for nelfilcon A and shorter for etafilcon A and omafilcon A, but the differences were not significant. NIK-DUT f did not differ significantly among nelfilcon A, etafilcon A and omafilcon A DDCLs at all visits (p=0.36). Subjective wettability grades after 5 mins, 8 hrs, and 12 hrs differed significantly for etafilcon A (P <0.01) and omafilcon A (p < 0.01), but not for nelfilcon A (p = 0.05), DDCLs. Conclusion: Grading was sufficiently sensitive to differentiate the wettability performances of the three lens materials. Nelfilcon A maintained wettability over the wearing period, whereas etafilcon A material showed faster dewetting at 8 and 12 hrs than at 5 mins after lens insertion.

<p>Comparison and Evaluation of Prelens Tear Film Stability by Different Noninvasive in vivo Methods</p>

“…Muller et al attempted measuring tear film stability using NIK-DUT, which was a method based on the conventional NIKBUT technique. 34 NIK-DUT was recorded from the blink until the appearance of the first distortion of the ring mire by using a stopwatch and not automatic detection. They concluded that although NIK-DUT did not differ significantly among three types of silicone hydrogel SCLs, their subjective wettability grades differed significantly.…”

<p>Objective Analysis of Pre-Lens Tear Film Stability of Daily Disposable Contact Lenses Using Ring Mire Projection</p>

“…The comfort and vision results were reported previously. 38 There were no adverse events during the study.…”

“…Although subjective evaluation was able to determine the first noticeable ring distortion and grade wettability, this procedure is very time consuming in practice. 38 The objective approach may reduce the time necessary to evaluate the captured information. Future studies can evaluate new endpoints that better account for the dynamics of the pre lens tear film and that are not limited to a certain time point as in the present study.…”

“…five different zones of the lens surface at different time points during the inter-blink period. 38 In contrast, the present study describes the results of software-supported analyses of the reflected ring mire, a more user independent approach of evaluating the performance of soft contact lens after 12 hours of wear.…”

“…Compared with the fully subjective evaluation of the Placido rings reflected from the lens surface, 38 the objective approach uses a grid that centrally overlies the video. It allows software to highlight detected ring distortion as an indicator of the dewetting process.…”