Peripheral Visual Evaluation of Eccentric Correction in Subjects With Large Central Visual Field Loss

Abstract

Abstract: : Purpose: Subjects with central visual field loss (CFL) have to rely on their remaining peripheral vision for all visual tasks. At large angles, eccentric vision is limited both by the resolution capacity of the peripheral retina and by the large off–axis errors in the optics of the eye. The aim of this research is to improve the visual function in subjects with absolute CFL by correcting the optical errors that arise when using eccentric viewing and preferred retinal locations (PRL). Methods: Two methods were used to measure eccentric optical errors: photorefraction and wavefront measurements with a Hartmann–Shack sensor. To evaluate improvements, psychophysical procedures for peripheral visual evaluation (PVE) were used to test detection and resolution acuity at high and low contrasts. Results: As a first step in improving the peripheral optics of the eye, the optimal eccentric refraction was found. In comparison to earlier foveal correction, eccentric correction resulted in a subjective improvement of visual performance in practical use. This was also confirmed by the psychophysical tests. Conclusions: Correction of large off–axis optical errors, based on individual measurements, can improve eccentric vision in subjects with CFL. Eccentric measurements are often more difficult to carry out than foveal measurements due to the large aberrations and poor stability in fixation. However, this work shows that wavefront measurement is a fast and easy method for assessing eccentric refraction.

Keywords: low vision • refraction • age-related macular degeneration