Effect of Monochromatic Induced Aberrations on Visual Performance Measured by Adaptive Optics Technology

Abstract

The two objectives were 1) to measure visual acuity (VA) and contrast sensitivity (CS) losses induced by various amounts of individual Zernike aberrations, and 2) to examine the accuracy of image quality metrics in predicting these visual performance losses. Monocular 10 cycles/degree (cpd) and 25 cpd CS and high- and low-contrast VA were measured when introducing individual Zernike aberrations in four patients dynamically corrected using a CRX1 adaptive optics system (Imagine Eyes) and a 5.5-mm pupil. Seven levels (0, +/- 0.1, +/- 0.3, and +/- 0.9 microm) of astigmatism, spherical aberration, coma, and trefoil and four levels of defocus were induced. Several image quality metrics based on the radially averaged modulation transfer function (rMTF) and optical transfer function (rOTF) calculations were computed to attempt to predict the losses in VA and CS. Modes near the center and at the top of the Zernike pyramid decreased VA significantly more than modes near the edge or at the bottom of the pyramid. The measured CS losses were reasonably correlated to the rMTF calculated at 10 cpd (R2 = 0.87) and 25 cpd (R2 = 0.75). The high-contrast VA degradations were also reasonably predicted (R2 = 0.85) by the intersection between the rMTF and the neural contrast threshold function. The low-contrast VA losses were also well predicted (R2 = 0.88) by three rMTF-based metrics. Image quality metrics based on wavefront aberration measurements were able to predict the impact of individual Zernike aberrations on CS and VA.