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L Thai, MG Doane, A Tomlinson; Effect of Different Soft Contact Lens Materials on the Tear Film . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3083.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: This study measured evaporation rate, thinning characteristics, and lipid layer changes in the pre-lens tear film (PLTF) associated with wearing of different soft contact lens materials, in an attempt to determine the biocompatibility of the material with the PLTF. Methods: 20 habituated contact lens wearers wore 5 different soft materials in a random order on the left eye, at visits separated by at least 24 hours. The soft contact lens materials were polymacon (Optima 38), omafilcon A (Proclear Compatibles), phemfilcon A (DuraSoft 2), balafilcon A (PureVision) and etafilcon A (Acuvue). Tear film evaporation rate was measured by a modified Servo Med evaporimeter and tear thinning time (TTT) by HirCal grid. Tear film structure and thinning were recorded dynamically with a Doane tear film video interferometer and graded according to a new system developed in the study. Baseline measurements were taken of the pre-corneal tear film (PCTF) before lens insertion and for the pre-lens tear film (PLTF) data, 30 min after commencing lens wear. Results: No statistically significant differences were found for any of the baseline (PCTF) data. There was also no significant difference in evaporation rate change (ANOVA) and in TTT (Friedmann) between the 5 contact lenses. In the PLTF quality grading, omafilcon A had significantly more stable grades than polymacon (Friedmann, p=0.01) and phemfilcon A (p=0.012). In PLTF observation of tear thinning and elimination rate, there was a significantly slower effect (better grade) observed for etafilcon A than polymacon (p=0.001). There was no significant difference in the overall PLTF wettability grading between any of the lenses worn. Conclusion: Generally, all soft contact lens materials significantly affect tear physiology by increasing the evaporation rate and decreasing TTT. The surface wettability of all contact lens materials was essentially the same irrespective of the special surface treatments. Only in PLTF quality and in PLTF elimination rate were differences found from the conventional low water content materials; omafilcon A was better in PLTF quality and etafilcon A had slower PLTF elimination rate.
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