MODELING HUMAN EYE ABERRATIONS AND THEIR COMPENSATION FOR HIGH-RESOLUTION RETINAL IMAGING

We introduced a mathematical eye model using Gullstrand's six-surface eye model modified by clinically measured aspherical data to study hum an eye aberrations and their compensation for high-resolution retinal imaging. Ray tracing was used to characterize aberrations and point sp read functions (PSFs) of the eye model. By using the Zernike polynomia l decomposition of the calculated pupil function, we quantified the wa vefront aberrations. Based on calculated PSFs, we designed optical inv erse filters to reduce the aberrations for a large pupil size and impr ove the resolution. Spherical aberration and oblique astigmatism were found to be in good agreement with published experimental measurements . Spherical aberration and defocus were the most significant aberratio ns for on-axis imaging, whereas oblique astigmatism and coma combined with spherical aberration and defocus were most significant for off-ax is imaging. The best retinal image resolution occurred at 2- to 3-mm p upil diameter. After aberration correction for an 8-mm diameter pupil, the resolutions for on-axis or 9 degrees off-axis imaging points were very close to diffraction-limited resolutions. Over a limited field o f view (FOV), retinal image resolution of the eye model can be greatly improved by aberration correction using aspheric and astigmatic lense s. For imaging large FOVs, space-variant compensation techniques will be required for aberration correction.