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M.-L. C. Coles-Brennan, N. A. Brennan, H. R. Connor, R. G. McIlroy, S. Gavras, K. Moody, T. Henderson; Short-Term Corneal Endothelial Response to Wear of Silicone-Hydrogel Contact Lenses in Asian Eyes. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4865.
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To evaluate the role of silicone-hydrogel (Si-Hy) contact lens oxygen transmissibility (Dk/t) on the corneal endothelial bleb response in eyes of East Asian subjects.
A total of 24 subjects of East Asian origin, attended for three separate sessions for a prospective, single-centre, trial. The following Si-Hy contact lenses were used: ACUVUE ® ADVANCETM with HYDRACLEARTM (Advance, -3D), ACUVUE ® OASYSTM with HYDRACLEARTM Plus (Oasys, -3D) and Focus® NIGHT & DAYTM (Night & Day, -3D). SofLens® 38 (+3D) was used as a positive hydrogel control. A modified Balaam’s crossover design was used to randomize presentation of sessions and contact lenses within sessions. Session one was a comparison between Oasys and SofLens 38 under closed eye conditions, session two was a comparison between Advance and Night & Day with eyes open and session three was a comparison between Oasys and Night & Day worn during eye closure. Corneal endothelial images were captured with the Topcon SP-3000P non-contact Specular Microscope after 20 minutes of wear and 5 and 10 minutes later after lens removal. Blebs were manually identified on these digital images by a masked observer. The area of blebs and total area under consideration were derived using IMAGEnetTM software and used to calculate percentage area of blebs. A boundary of equivalence of 1% was used as a clinically significant bleb area difference, and two-sided 95% confidence intervals were utilized to evaluate differences between lenses within each session.
In session 1, Soflens 38 produced a mean percentage area of blebs of 8.0% after 20 minutes, which was significantly different to that produced by Oasys (1.6%). In session 2, both Advance and Night & Day produced a mean percentage bleb area of 0.4%. In session 3, Oasys and Night & Day produced mean percentage bleb areas of 1.7% and 2.0%, respectively. The differences between Si-Hy lenses in sessions 2 and 3 were not statistically significant. Recovery from the bleb response was essentially complete in all cases except Soflens 38 within 10 minutes of lens removal.
The similarity of bleb responses induced by the Si-Hy lenses under the tested wearing conditions is consistent with the proposition that increases in Dk/t above a certain level will produce minimal change in corneal physiological conditions.
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