Asymmetric Peripheral Refraction Profile in Myopes along the Horizontal Meridian.

Abstract

The investigation of peripheral refraction profiles in Indian myopes showed relative peripheral hyperopic refraction in temporal retina and possible dominant role of hyperopic defocus signals from temporal retina in the development of myopia. Considering that the peripheral refraction profiles were extensively reported to be associated with the central refractive error and vary among different ethnicities, we investigated the peripheral refraction profiles in Indians. A total of 161 participants aged between 18 and 33 years were included in the study. All of the eligible participants underwent a comprehensive eye examination. Central and peripheral refractions were determined using an open-field autorefractor in 10° intervals up to ±30° in the horizontal meridian, and in 5° intervals up to ±15° in the vertical meridian. Axial length and central corneal radius were measured using a non-contact optical biometer. Peripheral refraction was compared between the different refractive error groups and myopic subgroups. Myopes showed a significant asymmetrical peripheral refraction profile along horizontal meridian with relative peripheral myopia at nasal 30° and relative peripheral hyperopia at temporal 30° (mean ± standard error at N30°: -0.37 ± 0.13 D vs. T30°: +0.56 ± 0.11 D, P < .05). Emmetropes and hyperopes showed relative peripheral myopia both in nasal and temporal eccentricities. Relative peripheral refraction was significantly different between the refractive groups and myopic subgroups along the temporal retinal eccentricities only (P < .05). Along the vertical meridian, relative peripheral myopia was seen among the three refractive error groups (P < .05). J0 and J45 significantly changed with retinal eccentricity along both the meridians in all the refractive error groups (P < .05). Myopes showed an asymmetric type of peripheral refraction with relative hyperopic defocus in temporal retina and myopic defocus in the nasal retina. Possible role of retinal hyperopic defocus along temporal retina in myopiogenesis needs to be explored.