Measuring Ocular Aberrations and Image Quality in Peripheral Vision With and Without Soft Contact Lens Correction

Abstract

Purpose: : To determine the ocular wavefront aberrations and image quality in peripheral vision both with and without Soft Contact Lens (SCLs) correction.

Methods: : The monochromatic aberrations of the left eye in 3 subjects were measured by a clinical aberrometer (COAS, Wavefront Sciences) both temporally and nasally out to 45º in 5º steps from fixation, with and without SCLs. No cycloplegia was used in the experiment in order to get naturalistic data. Commercial software (COAS, CLAS-2D) for Zernike analysis and image quality calculation was adapted for use with elliptical entrance pupils encountered in the peripheral vision.

Results: : Pupil dimensions estimated from the array of Shack-Hartmann spots captured by the wavefront sensor followed geometrical optics predictions up to 30º eccentricity in these three subjects. By using 5mm analysis pupil size in all eccentricities of the subjects, averaged data are reported in this study. For the uncorrected eye, total RMS wavefront error (up to 6^th order) increased about 1.6 microns from fovea to temporal 30º and 0.8 microns from fovea to nasal 30º. 2^nd-order RMS was the major component causing this variation. 3^rd-order RMS increased with the increasing eccentricity. After fitting with SCLs to fully correct foveal refractive error, both 2^nd-order and 3^rd-order aberrations increased gradually from fovea to periphery which makes the total RMS increased 5 fold up at 30º both in the nasal and temporal visual field. Breakdown of the 2^nd-order aberration shows that astigmatism Z₂² did not change significantly before or after fitting with SCLs, but defocus Z₂⁰ decreased significantly across the visual field after wearing SCLs. Retinal image quality computed by VSOTF showed significant increases after fitting with SCLs across the visual field. Image quality declined faster away from fovea with SCLs correction compared to uncorrected.

Conclusions: : Measurements of ocular aberrations and image quality in peripheral vision using clinical wavefront aberrometer are possible. Image quality decreased across the visual field with or without SCLs correction and SCLs can greatly improve retina image quality both in fovea and peripheral vision, which was mainly contributed by the effect that SCLs correct spherical refractive error.

Keywords: aberrations • contact lens