Visual Evaluation of Resolution Acuity With Eccentric Refractive Correction

Abstract

Purpose:: This study investigates the benefits of eccentric correction to resolution thresholds in different contrasts for seven subjects with absolute central visual field loss (CFL).

Methods:: Refractive correction in eccentric viewing angles using a preferred retinal location was assessed by photorefraction with the PowerRefractor instrument and by wavefront analysis using the Hartmann-Shack principle. The visual function with both eccentric and central corrections was evaluated using number identification in high and low contrast. For comparison four additional subjects with normal central vision were measured in 20° off-axis.

Results:: For the CFL subjects the resolution thresholds varied between individuals due to different preferred retinal locations and cause of visual field loss. However, all seven subjects showed improvements in resolution acuity with eccentric correction compared to central correction. In the healthy eyes improvements were only found in low contrast.

Conclusions:: Compared with healthy eyes the CFL subjects had lower resolution acuity with central correction and the eccentric refractive correction improved resolution to levels comparable to healthy eyes. These results imply that optical eccentric correction can be beneficial for subjects with CFL in situations where healthy eyes don’t show any improvement.

Keywords: low vision • visual acuity • refraction