Peripheral optical errors and their change with accommodation differ between emmetropic and myopic eyes

TLDR

Myopia progression is thought to be driven by retinal image quality, yet the specific triggers remain unclear, and differences in peripheral optics between emmetropic and myopic eyes may underlie the development of myopia. This study investigates peripheral optical quality and its modulation by accommodation. The authors measured refraction and aberrations of the right eyes of five emmetropes and five myopes with a peripheral Hartmann–Shack wave‑front sensor, evaluating off‑axis optical quality at 10° increments up to ±40° horizontally and ±20° vertically under near (4.0 D) and far (0.5 D) accommodation. Emmetropes exhibited greater relative peripheral myopia than myopes, with the difference being asymmetric across the visual field and expanding with accommodation, whereas myopes showed no consistent change; these results suggest that accommodation‑dependent peripheral defocus may be a key factor in myopia progression.

Abstract

The progression of myopia is thought to be controlled by the retinal image quality, but its triggering factors are not yet well known. The differences between the peripheral optics in emmetropic and myopic eyes might explain why some eyes become myopic. The present study further investigates peripheral optical quality and how it is affected by accommodation. The refraction and aberrations of the right eyes of five emmetropes and five myopes were measured using a laboratory Hartmann–Shack wave front sensor, specially designed for peripheral measurements with an open field of view. The off-axis optical quality was assessed in steps of 10° out to ±40° horizontally and ±20° vertically for two different states of accommodation (targets at 0.5 D and 4.0 D). As expected, the emmetropes had a higher relative peripheral myopia, that is, more positive c 2 0 coefficient, than the myopes. The new results of this study are that this well-known difference was found to be asymmetric over the visual field and that it increased with accommodation. This increase was because the relative peripheral defocus profile of the myopes did not show a consistent change between far and near vision, whereas the emmetropes became relatively more myopic in the periphery with accommodation. These findings may indicate a difference between emmetropic and myopic eyes that could be an important clue to understand myopia progression.