Asymmetry between nasal and temporal refraction with accommodation in myopes and emmetropes.

This study investigates relative peripheral refraction (RPR) in emmetropic and myopic eyes in the 25° nasal and temporal visual fields under far and near fixation, with control for any fluctuations in accommodation. Additional analysis of axial length and comparison with recently published eye models are also presented, constituting complementary adult data to the Stockholm Myopia Study. In the ten emmetropes, a pronounced nasal-temporal asymmetry was observed, with significantly more myopic RPR nasally and less myopic / more hyperopic RPR temporally at both accommodative states (p = 0.005). The nine myopes, in contrast, exhibited more symmetric peripheral profiles, with no significant nasal-temporal differences. Accommodation induced systematic shifts in both groups, producing increased relative myopia nasally and relative hyperopia temporally (p < 0.001). Axial length was significantly correlated with temporal hyperopic shifts during accommodation in myopes (p = 0.005), suggesting a structural contribution of ocular growth to peripheral optics. Comparison with eye models showed partial agreement, though experimental results revealed greater asymmetry than predicted in emmetropes and a weaker nasal-temporal distinction in myopes. Our findings indicate that variations in relative peripheral refraction over the horizontal visual field and with accommodation might be linked to ocular growth and are important for optical myopia control.