Abstract
Purpose :
The remaining peripheral vision of subjects with central vision loss improves with optical correction, however contrast sensitivity (CS) is still reduced in the eccentric preferred retinal locus (PRL) compared to the healthy periphery. It is known that moving stimuli improve CS at low spatial frequencies for normal subjects. The aim of this study was to improve the CS in a subject with central vision loss through a combination of optical correction and stimulus motion.
Methods :
Grating resolution acuity and CS for resolution were evaluated in the PRL of a 24-year-old subject with stable Stargardt’s macular degeneration. All measurements were performed in the PRL located at 17° in inferior-nasal visual field of the left eye. The subject had no habitual optical correction; COAS open field Hartmann-Shack wavefront aberrometer determined the eccentric refractive correction to be -1.50/-3.50x170. Low (25 and 10%) and high contrast resolution acuity for stationary sinusoidal gratings with and without refractive correction were measured. Additionally, high contrast resolution acuity for moving gratings (7.5 Hz drift within a fixed Gaussian window) and CS measurements at 0.5 and 1.0 cycles per degree (cpd) for stationary and moving gratings were performed with refractive correction.
Results :
The resolution acuity at 25% contrast improved significantly from 1.56±0.06 to 1.41±0.06 logMAR (p<0.05) with refractive correction, but the subject was not able to resolve the gratings at 10% contrast. High contrast acuity did not change significantly with optical correction (1.22±0.04 and 1.25±0.02 logMAR with and without optical correction) nor for moving stimuli (1.26±0.05 logMAR). The log CS for 0.5 cpd improved significantly from 0.88 to 1.08 when the stimulus was moving, corresponding to resolution of gratings with contrast as low as 8%. However, the change was opposite for 1.0 cpd, where the log CS decreased from 0.75 to 0.54 for moving stimulus. This is understandable as 1.0 cpd was close to the resolution cut-off.
Conclusions :
Peripheral optical correction improved low contrast acuity, and movement of low spatial frequency stimuli improved resolution CS in a subject with central visual field loss. A combination of optical correction, magnification to display low spatial frequency stimuli and stimulus movement through moving or jittering text could have the potential to improve vision in the eccentric PRL.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.