Correction of peripheral refractive errors and its impact on visual performance

Abstract

AbstractPurpose There has been considerable recent interest in modifying peripheral refraction for the purpose of treating myopia. Correcting peripheral refraction can affect peripheral visual performance. The purpose of this study was to consider the extent of such improvement and the feasibility of making spectacle lenses for this purpose.Methods Peripheral refraction was used as a basis for designing lenses to correct refraction out to 30 degrees along the horizontal meridian. Visual performance tests were conducted at 20 degrees nasal, 30 degrees nasal and 25 degrees temporal visual field. Tests were detection acuity for high contrast sinusoidal gratings and contrast thresholds for 1 min arc diameter spots.Results Correcting peripheral vision has limited influence on visual acuity as this and other resolution‐like tasks are limited more by retinal sampling than by image quality. However, Lewis et al (ARVO abstract 2012) found that correcting vision at 20 degrees nasal visual field could improve low contrast resolution acuity by an average of 0.06 log unit and up to 0.16 log unit for people with large off‐axis astigmatism. Detection tasks, such as deciding in which of two presentations a grating appears without necessarily being resolvable, give up to 0.7 log unit (5 times) better acuity than resolution tasks at 20 deg N, but are sensitive to defocus such that performance reduces close to those of resolution tasks with about 2 D defocus (Wang et al, IOVS 1997). Results like the above indicate the potential value of peripheral correction for people with macular lesions. Our own results with specially designed lenses will be presented.Conclusion The lenses were partially successful in improving peripheral vision. Difficulties included variability in peripheral refraction measurements and lack of sensitivity of some subjects to peripheral correction. Whether or not correcting peripheral refractive errors will influence myopia progression is not yet known.