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S. H. Sinclair, W. Gutstein, R. V. North; Effect of Myopia Correction With Spectacles, Soft Contact Lenses or Orthokeratology Lenses on VA Measured Under Luminance and Contrast Conditions That Mimic Real World Environments. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3977.
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© ARVO (1962-2015); The Authors (2016-present)
To compare VA measured after removal of orthokeratology (O-K) lenses compared with soft contact lens aberration controlled (CTL) or spectacle (SPC) correction of similar myopia under luminance and contrast conditions that mimic real world mesopic and glare environments.
The VA of two groups of normal myopic eyes -0.50 to -5.5 DS (<-0.75 cyl) were compared: 1) 52 eyes having worn O-K lenses for 2 months to 2 years, measured 6 hours after removal of the lenses and 2) 151 eyes measured first with SPC and then while wearing CTL. VA was measured with the Central Vision Analyzer, an interactive computer program that presents 250msec, tumbled, Landolt C’s and thresholds for the smallest C correctly discriminated (threshold 2 correct answers at the lowest optotype size, with 2 incorrect at the next lower utilizing logMAR 0.05 steps). The CVA tests 3 mesopic environments and 3 glare environments with contrasts that mimic real environments of daily living activities. For each condition mean VA and standard deviation were calculated with a two tailed, T-Test to examine significant differences between the optical corrections.
A significantly worse VA was noted with O-K lenses compared with both SPC and CTL under the mesopic and glare conditions with lowered contrasts (table).
The corneal zone treated by O-K lenses is limited to 6mm and combined with higher order aberrations produced poorer VA’s compared with spectacles and CTL especially in mesopic and glare conditions with reduced contrasts. If contrasts were sufficiently high (i.e. MC 99%) no differences were noted.
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