Simulation of Retinal Images in an Eyes with Keratoconus with Asymmetric Aberrations Using the Point Spread Function Analyzer

Abstract

Abstract: : Purpose: To simulate retinal images in eyes with keratoconus with asymmetric aberrations using a new point spread function analyzer (PSFA). Methods: A point light source was projected onto the eyes of patients with keratoconus, the reflected images at the retina were captured by the charge–coupled device, and the PSFs were analyzed (double–pass formula). Modulation transfer functions (MTFs) of the optical systems were obtained through equal–sized apertures as entrance and exit pupils and the phase transfer functions (PTFs) through unequal–sized apertures; the simulated retinal images then were reconstructed by a process in which the Fourier spectrum of the original chart was multiplied by the MTFs and the PTFs as the phase term of the original chart were added. The simulated retinal images of the E charts were compared with subjective sensations in the same subject. Different sized E charts were observed with the eyes with keratoconus and the subjectively observed images were depicted using the fellow eyes without remarkable corneal abnormality with a best–corrected hard contact lens. Results: The characteristics of the simulated retinal images of the E charts objectively synthesized with optical data by PSFA coincided with those of the depicted images from subjective observation. The simulated retinal images from the eyes with keratoconus showed characteristics of asymmetric aberrations without loss of the high–frequency range of spatial frequency. Conclusions: The PSFA can simulate retinal images from eyes with keratoconus with asymmetric aberrations and is useful to objectively evaluate the characteristics of the visual function of patients.

Keywords: keratoconus • image processing • optical properties