Effect of Retinal Steepness on Central Refractive Changes in Children

Abstract

Purpose: : Increasing evidence suggests that peripheral refraction influences refractive development. Peripheral refraction has been shown to correlate with retinal steepness, defined as the difference between peripheral and central eye length. The purpose of this study was to determine the effect of retinal steepness on central refractive changes in children.

Methods: : Central sphere refraction and central sphere equivalent refraction (CSR and CSER; Shin-Nippon K5001 open-field autorefractometer) and retinal steepness (custom-made optical low coherence interferometer) were assessed in right eyes of 89 children at baseline and after an average of 30 months follow-up. For the estimation of retinal steepness, eye length was measured along the visual axis and at the nasal, inferior, temporal and superior retina using fixation targets placed at 20 degrees of visual field angle. Retinal steepness was then calculated at each peripheral location. The correlation between change in CSR or CSER and retinal steepness was evaluated with a multiple regression analysis.

Results: : At baseline, the children were between 7 and 11 years old, and emmetropic or near-emmetropic (CSER = 0.06 ± 0.54 D; mean ± SD). Normalized changes in CSR and CSER over a 30-month period were -0.24 ± 0.54 D and -0.21 ± 0.57 D, respectively. Significant correlation was observed between retinal steepness and changes in CSR (p=0.012) and CSER (p=0.005), albeit with low adjusted correlation coefficients (R²) around 11%. Temporal retinal steepness correlated best with changes in CSR and CSER (p=0.046 and p=0.051; simple regression), while nasal retinal steepness correlated worst. Changes in CSR and CSER both correlated with axial elongation (p<0.0001) as normalized over the same time period, with R² of 19% and 15%, respectively.

Conclusions: : The significant correlation between retinal steepness, particularly at the temporal retina, and central refractive change supports the hypothesis that peripheral eye shape contributes to visually guided eye growth. The low adjusted correlation coefficients, however, indicate that factors in addition to retinal steepness and its associate, peripheral refraction, affect refractive development.

Keywords: refractive error development • emmetropization • myopia