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A.B. Watson, A.J. Ahumada; Predicting Acuity From Aberrations With the Spatial Standard Observer . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3614.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate the Spatial Standard Observer as a method of predicting visual acuity from measured wavefront aberrations. Methods: Recent technology makes it possible to measure and modify the wavefront aberrations of the human eye. As a result there is considerable interest in methods to predict visual acuity or image quality from wavefront aberrations. The Spatial Standard Observer (SSO) is a simple model that predicts the detectability and discriminability of foveal spatial contrast targets. SSO predictions are based on the generalized energy of visible contrast. Visible contrast is luminance contrast attenuated by a contrast sensitivity function (CSF) and a spatial aperture. Generalized energy means that the visible contrast is raised to a power higher than 2 before spatial integration. To predict acuity for an observer with particular wavefront aberrations, we removed the optical component of the SSO CSF (leaving the neural CSF) and replaced it with the observer's specific visual optics. We could then compute SSO discriminability measures for any pair of Sloan letters, and could predict acuity measurements based on the ensemble of discriminabilty measures for the complete Sloan letter set. Results: Predictions of acuity based on the Spatial Standard Observer correlate well with empirical results. The SSO performs as well or better than prior methods, but also provides absolute, rather than relative predictions. We will compare the SSO predictions to those from other metrics, and will discuss the contribution of model components to the success of the predictions. We will also discuss simplifications of the model that may increase the practicality of the method. Conclusions: The Spatial Standard Observer accurately predicts acuity from wavefront aberration measurements.
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