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Dorota Helena Szczesna-Iskander, Maciej Bartuzel, Szymon Adamus, D Robert Iskander; OCT based meniscometry for evaluating tear film behavior on contact lenses. Invest. Ophthalmol. Vis. Sci. 2014;55(13):6056.
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© ARVO (1962-2015); The Authors (2016-present)
To ascertain whether the parameters of contact lens material wettability measured in vitro have a correspondence in in vivo measured characteristics of lower tear film meniscus (LTM).
Using the spectral domain optical coherent tomographer (sOCT, Copernicus, Optopol, Poland) dynamic measurements of LTM were acquired at a rate of 25 B-scans, capturing the blink and about 3 seconds of post blink lower tear meniscus formation. Ten subjects (7F/3M) volunteered for the study. Multiple sOCT measurements were performed on separate days on bare eye and three types of soft contact lenses (comfilcon A, omafilcon A, balafilcon A) of power -0.50D, 40 minutes after application. The lens fitting characteristics were found to be adequate for all types of lenses. A dedicated algorithm for extracting tear meniscus parameters from sOCT scans was developed in Matlab. The algorithm output consisted of three time series representing the post blink dynamics of LTM height, depth and area. For differentiation of contact lens materials the group median of each LTM parameter was calculated. The statistical analyses included standard descriptive statistics and a nonparametric one way ANOVA (Kruskal-Wallis).
Median LTM height, depth and area for bare eye were 0.24±0.05mm, 0.20±0.04mm, and 0.021±0.009mm2, respectively. Apart from LTM height on balafilcon A (0.26±0.07mm), the group medians of all three parameters were lower on contact lenses than on bare eye. Among lenses, the highest values were established for balafilcon A, and these results were also statistically significantly different to the comfilcon A and omafilcon A (respectively: LTM height p=0.01 and p=0.03, LTM depth p=0.03 and p=0.03, and LTM area p=0.03 and p=0.04). These differences corresponded to lower assessment of subjective comfort and higher contact angle measured in vitro as compared to the other two lens materials. LTM height was the only parameter that indicated statistically significant differences between each pair of lenses (p=0.02 - comfilcon A: 0.17±0.07mm, omafilcon A: 0.21±0.06mm).
Dynamic meniscometry utilizing sOCT technology is a useful tool for evaluating the effects of contact lens material on tear meniscus parameters. The presence of contact lens on eye is not directly related to the LTM parameters which appear to be more associated with the characteristics of contact lens material.
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