Changes in peripheral refraction during myopia progression in children

Abstract

Purpose : Peripheral optics has been suggested to play a role in myopia progression. However, it is not yet known if changes occurring in peripheral refraction are a cause or a consequence of the myopization process. To study this issue further, we have performed a two-years longitudinal study in a group of children.

Methods : Peripheral refraction maps were measured using a specially designed wavefront sensor (VPR, Voptica SL, Murcia, Spain) in a group of Chinese children (age 9-16 years) under cycloplegia. The refraction maps covered a field from nasal 30° to temporal 30° of every 1°, and from superior 20° to inferior 16° of every 4°. The participants were classified into three groups based on the status of central refraction over time. A first group (G1, 21 subjects) maintained emmetropia during the whole study (EM-EM-EM). A second group (G2, 15 subjects) remained emmetropic in the first year but became myopic in the second year of the study (EM-EM-MY). In the third group (G3, 23 subjects), they became myopic already in the first year (EM-MY-MY). Refraction maps were divided into 9 equally sized rectangular regions for the comparison of relative peripheral refraction (RPR) among the three groups in the same visit, or the same stage prior to myopia (G1-24M vs G2-12M vs G3-baseline) and just become myopic (G2-24M vs G3-12M).

Results : Differences in the relative peripheral refraction (RPR) were observed in the first follow-up (12M) visit in both nasal and temporal retina for the three groups. All regions, except for the superior retina, show differences in the periphery in the second follow-up (24M) visit. No difference was found for RPR in all the peripheral regions for the stage prior to myopia (G1-24M vs G2-12M vs G3-baseline) and those that became myopic (G2-24M vs G3-12M). The figure shows graphically the results of the study.

Conclusions : We measured peripheral refraction in the whole retina in a group of children during a 2-year period. All subjects went through the same peripheral refraction patterns during the myopia progression. This is an argument in favor that the changes in peripheral refraction are more a consequence of myopia progression rather than a cause.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Figure. Average 2-D peripheral refraction maps for emmetropic children from baseline to the second follow-up visits. Map's coordinates in x-axis shows the horizontal meridian, with positive values being the nasal retina and negative values the temporal retina.