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Dorota Szczesna-Iskander, D Robert Iskander; Evaluation of the effect of soft contact lens edge shape on conjunctival epithelium. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5482.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize soft contact lens edge profile effect on conjunctival epithelium using optical coherence tomography.
Nine regular contact lens wearers were included in the study. 4 types of soft contact lenses were considered (3 monthly, 1 fortnightly, power ranged from -0.5 to -5.0D.). Subjects simultaneously wore two types of lenses (eyes were randomized). A week break was set between the 1st and the 2nd pair. All lenses evidenced acceptable fit. The inferior limbus area was imaged by SOCT Copernicus 40 minutes after lens application and after 2 weeks of daily wear. A novel method of differential analysis, overcoming problems associated with optical distortions, was applied to acquired images to evaluate the effect of contact lens edge shape on conjunctival epithelium. In particular, the difference in conjunctival deformation angle (Δθ) and the difference in the normalized contact lens imprint area (ΔS) were chosen for the statistical analyses which included standard descriptive statistics and the two-sided rank sum test for medians (Wilcoxon).
The largest difference in conjunctival topography between visits was experienced in SiHy lens with a round edge profile (group average±SD and median for Δθ: 21.1±8.4° and 18.7° and for ΔS: 7.0±2.4% and 5.4%). The Si-Hy lens with two-sided edge profile resulted in Δθ: 10.8±1.1°, ΔS: 3.6±4.6%; and medians of 9.8° and 5.4%, respectively. The smallest difference in the conjunctival deformation angle was observed in Si-Hy angle edged lens (Δθ: 0.2±3.1°; 3.0°, ΔS: 2.3±3.8%; 5.3%) while the difference in the normalized contact lens imprint area was negative (showing improvement) in Hy round edged lens (Δθ: 7.4±5.8°; 0.2°, ΔS: -6.7±4.2%; -9.0%). Statistically significant differences in Δθ were achieved between angle edged and round edged Si-Hy lenses (p=0.046), and angle edged and two-sided edged lenses (p=0.001). ΔS showed significant difference between round edged Si-Hy and Hy lens (p=0.021).
The study indicates that the soft contact lens edge shape plays little role in the presumable conjunctival epithelium imprint and suggests that other lens parameters, such as the material properties, may play a more significant role in this phenomenon.
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