Prediction of Defocused Visual Acuity by Simulated Retinal Images of Landolt’s Rings in Human Eyes

Abstract

Abstract: : Purpose: To evaluate the predicted visual acuity (VA) from the simulated retinal image in defocusing using a new point spread function analysis system (PSFAS). Methods: The clinical VA results and the VA predicted by this system were compared in two subjects 24 and 48 years old. The double-pass point spread functions (PSF) in defocusing was obtained using a new PSFAS in which a specular reflection double-pass method was used. The retinal images of various sized Landolt’s rings were simulated by convolution with single-pass PSFs calculated from double-pass PSFs. The contrast function corresponding to the VA was calculated from the intensity profile of the gap of the simulated retinal images of the various rings. The predicted VAs were determined from the intersection of the contrast function of each defocus position and the modulation threshold measured by Campbell and Green. We measured the VA in each subject with the addition of 0 to 3 diopters by 0.25 diopters of refractive error. Results: A correlation was seen between the results of the predicted VAs and the clinical VAs in the two subjects. The correlation coefficients were exceeded 0.8 in the defocusing range from 0 to 1.5 diopters in the two subjects. Conclusion: The PSFAS simulated the retinal images at the entrance of the visual nervous system. The retinal images of the various Landolt’s rings simulated by PSFAS were the eye’s optical characteristics inclusive of the Stiles-Crawford effect.

Keywords: 368 contrast sensitivity • 500 optical properties • 519 physiological optics