Eye shape and peripheral refraction as predictors of myopia progression in a population of Chinese children

Abstract

Purpose: Eye shape and peripheral refractive state may be related to myopia development and progression. In this longitudinal study of Chinese children we examined these factors as possible predictors of the development of myopia using a multiple regression analysis.

Methods: Forty-one children (age: 11.5±0.98 years) were recruited from primary schools in Wenzhou, China, and were classified as emmetropes (n=23; axial MSE refraction: +0.75 to -0.25 D) or low myopes (n=18; -0.5 to -2 D). Thirty-one children were reexamined for follow-up after an average of 2.7 years (range 2.3-4.5 yrs). Measures included in the analysis were on- and off-axis refractive state (retinoscopy and Grand Seiko WAM-500 open field autorefractor), axial length (IOLMaster), and eye shape (MRI).

Results: At the follow-up measurements, the average refractive change for all subjects was -1.25±1.04D and only 6 out of 31 subjects were not myopic. When all subjects were evaluated together, a multiple regression model that included baseline measurements of on-axis MSE refraction, axial length, the axial/equatorial eye length ratio measured from the central sagittal plane, the nasal-temporal asymmetry in VC depth, and the relative peripheral refraction at 30 deg temporal on the tangential plane significantly predict the on-axis refractive change and growth rates at follow-up (R²=0.55 p<<0.01; R²=0.31 p<0.05). However, when only the emmetropes at baseline were analyzed, the best predicting models of changes in axial MSE refraction and eye growth included only baseline measurements of on-axis refraction, axial length, and relative peripheral refraction at 30 deg temporal on the tangential plane (R²=0.52 p<0.02; R²=0.52 p<0.02).

Conclusions: Baseline refractive state and eye length were significant predictors of changes in refractive error and ocular growth in this small-scale study. Specific measures of eye shape and peripheral refraction combined to improve prediction to 55% of the variability in developing myopia. These data support the hypotheses that eye shape and peripheral refractive state are factors in the visual control of eye growth and the development of refractive state. However, only peripheral refraction, but not eye shape, was a factor in the emmetropes that developed myopia at follow-up.

Keywords: 605 myopia • 677 refractive error development • 464 clinical (human) or epidemiologic studies: risk factor assessment