Measurement of 360° Peripheral Refraction Profile in Emmetropic and Myopic Young Human Eyes

Abstract

Purpose : Prior studies have measured refraction along the horizontal, vertical and few oblique retinal eccentricities. However, 360° peripheral refraction profiles of human eyes have not been measured. Hence, the goal of this study was to measure and compare the 360° peripheral refraction profile in emmetropic and myopic eyes.

Methods : Twenty healthy young subjects (10 emmetropes and 10 myopes) aged between 17 to 25 years were recruited. Myopic eyes had spherical refraction of ≤ -3 D and astigmatism of ≤ 2 D. Right eyes were cyclopleged with 1% cyclopentolate eye drops. Three refraction measurements in the right eye were recorded using a Grand Seiko autorefractor (WAM 5500) at each of the predetermined 185 locations across all meridians in 10° steps, spanning a total of 30° horizontal and 15° vertical visual fields. Mean values of spherical equivalent refraction (SER), J₀ and J₄₅ were measured at each eccentricity. Sector-wise comparisons were performed along 4 sectors: a) horizontal (nasal-temporal) b) vertical (superior-inferior) c) oblique (superior-temporal inferior-nasal [ST-IN]) and d) superior-nasal inferior-temporal [SN-IT] for both the groups.

Results : In all 4 sectors, the SER for myopic eyes showed a relative hyperopic shift in the periphery, with the temporal periphery becoming almost equal to the foveal refraction at 30° eccentricity. The J₀ component showed relative hyperopia in the nasal half of the retina for the first 15° and then progresses to become more myopic in the periphery for both the emmetropic and myopic subjects. The J₄₅ component has a relatively similar outcome for both groups with the ST-IN sector being hyperopic in the periphery and the SN-IT sector being myopic in the periphery. The vertical and horizontal sectors remain relatively close to the foveal refractive error throughout the eccentricities for both the groups.

Conclusions : The study showed that there are significant sector-wise changes in refraction at the periphery as compared to fovea. With all the 360° meridians considered in this study, it provides a valuable insight into an eye’s complete refractive error profile.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Sector-wise representation of the 185 predetermined locations (black and red dots) where refraction was measured.