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Ayeswarya Ravikumar; Quantifying Visual Acuity from Image Quality Metrics. Journal of Vision 2016;16(4):38. doi: https://doi.org/10.1167/16.4.37.
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© ARVO (1962-2015); The Authors (2016-present)
Wavefront error (WFE) of the eye has been shown to vary from individual to individual and within an individual as a function of pupil diameter. Of current interest in the area of refractive correction development is the relationship between the aberration experienced by an eye, and resulting visual performance. In a set of experiments, WFE for both normal and keratoconic eyes were selected from published datasets. These WFEs were then used to generate computationally blurred logMAR acuity charts, simulating retinal image quality under a variety of test conditions. Test subjects read the computationally blurred charts to assess the impact of the residual WFE on resulting acuity. These experiments demonstrated that the visual quality metric visual Strehl calculated in the frequency domain (VSOTF) can detect blur before clinically significant change in acuity occurs. These experiments also demonstrated that change in log neural sharpness (logNS) and log visual Strehl ratio in the spatial domain (logVSX) were both highly correlated and predictive of change in VA in both the normal and highly aberrated eyes, independent of pupil diameter. Studies are in progress that utilize these metrics to objectively predict sphero-cylindrical correction, to optimize the design of wavefront guided corrections, and to evaluate optical corrections objectively for both normal and highly aberrated eyes prior to dispensation of the correction.
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