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W. Gutstein, S.H. Sinclair; Comparison of Glasses versus Purevision and Biomedic Contact Lens Wear on Vision under Varying Conditions of Luminance and Contrast . Invest. Ophthalmol. Vis. Sci. 2006;47(13):92.
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© ARVO (1962-2015); The Authors (2016-present)
Current paper chart or monitor systems test vision with visual acuity or contrast sensitivity under a single lightning condition of the examining lane. We wished to measure whether contact lens (CL) wear altered vision under contrast and lighting conditions that mimicked normal day and evening activities.
Normal individuals were selected with spherical myopia of –0,50 to –5.0. Vision was tested with an interactive computer graphics method that presents Landolt Cs against a background for 250 msec on an LCD screen, tumbled in 1 of 4 directions. The patient responds by pushing one of 4 buttons on a response pad. Using size steps equal to the ETDRS, the program thresholds for the smallest size correctly identified with two incorrect responses at the next level smaller; 6 conditions are tested in sequence: 1) 98% Michelson contrast white letters against a black background of 0.4Cd/M2
2) 5%gray–black letters against a black background of 0.8Cd/M2
3) 10%gray–black letters against a black background of 1.68Cd/M2
4) 20%gray–white letters against a white background of 23.6Cd/M2
5) 10% gray–white letters against a white background of 29Cd/M2
6) blue letters representing a contrast of 5% against a yellow background of 30Cd/M2.
Vision was measured first with best spectacle correction and then after 1 hour wear of each of Purevision (B&L) and Biomedic (Ocular Sci) CL with a 30 minute break between.
Sixteen eyes of 8 individuals were tested, ages 22 to 35
Purevision CL wear for short durations produced significantly better resolution than with spectacles under mesopic test conditions of 5% and 10% contrasts and in photopic conditions of 10% contrast. Biomedic CL demonstrated better vision over spectacles only in mesopic luminance with 10% contrast. Comparing Purevision CL wear against that of Biomedic CTL, better resolution was noted with Purevision under mesopic 10% contrast conditions and 10% contrast photopic conditions. These observations represent only those of a pilot cohort under a limited number of mesopic and photopic conditions that mimic day and evening activities.
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