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Ayeswarya Ravikumar, Edwin J. Sarver, Raymond A. Applegate; Change In logMAR Acuity Is Highly Correlated With Change In Certain Image Quality Metrics In Both Normal And Keratoconic Eyes. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3599. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To determine if change in logMAR visual acuity (VA) is highly correlated with change in key image quality (IQ) metrics in both normal and highly aberrated eyes.
15 normal, best corrected wavefront errors (WFEs) were randomly selected from the Thibos et al (J Opt Soc Amer A 19, 2329-48; 2002) 100 normal eye data set and 7 keratoconic (KC) WFEs from the Marsack et al data set (Optom Vis Sci 2007;84: 463-470). All WFEs were rescaled to a 4mm pupil. These 22 WFEs were scaled in magnitude up and down to yield 12 levels of WFE and in turn to calculate 30 IQ metrics. The wavefront error of 2 normal subjects was measured through their best corrections. For each subject, for each of the 264 WFEs, 3 unique acuity charts of 30% contrast were simulated after pre-compensating for the measured residual aberrations over a 3mm pupil, yielding 792 (22 * 12 * 3) unique logMAR chart simulations for each subject. For each chart, VA was measured on the 2 subjects up to the 5th letter missed through a 3mm pupil placed conjugate with the subject’s dilated pupil. VA was recorded as the change in VA (VA for test chart of interest - average VA obtained on 3 unaberrated charts). The resulting ΔVA was linearly regressed against change in each of the 30 IQ metrics in normal and KC eyes separately and in combination.
Change in logMAR acuity is highly correlated (R2 greater than 0.75) with change in 3 log IQ metrics (neural strength, visual Strehl, light in the bucket) regardless of whether the eye is normal or highly aberrated supporting each IQ metric's role as a viable objective surrogate for visual acuity.
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