Peripheral Blur Perception in Young Children at Low Risk or High Risk of Myopia: Longitudinal Data.

Purpose: Peripheral sensitivity to blur may contribute to refractive error development. We assessed blur discrimination in the near periphery in emmetropic children (six to eight years) at low risk (LR, n = 48) or high risk (HR, n =43) for myopia over three years. Methods: A synthetic image with naturalistic image statistics was digitally blurred (pedestal blur) with either simulated defocus or primary spherical aberration (SA). One quadrant of the display was blurred by an additional amount (increment blur) and the subjects indicated that quadrant. Blur levels were adjusted using QUEST+ adaptive algorithm across three eccentricities (0°, 6°, 12°). Dipper functions were fit to proportions correct as a function of pedestal and increment blur to estimate intrinsic blur and blur criteria. Generalized mixed models were used to describe the effect of eccentricity, visit, and risk group on each blur measure. Results: There was no significant main effect of risk group, but intrinsic blur decreased significantly more over time in the HR group [defocus: -0.02 log (µm), P = 0.015; SA -0.03 log (µm), P = 0.005]. Intrinsic blur for defocus [0.11 log (µm), P < 0.001], but not SA, was higher for 6° than 0°. Intrinsic blur [defocus: 0.42 log (µm), P < 0.001; SA: 0.41 log (µm), P < 0.001], and blur criteria (defocus: 0.12 log, P < 0.001; SA 0.05 log, P = 0.001) were higher for 12° than 0°. Conclusions: Peripheral blur perception is impaired by elevated intrinsic blur and higher discrimination criteria compared to central vision in children at LR and HR for myopia, with larger transition between 6° and 12° eccentricity. Peripheral blur perception does not appear to be a predictive factor in myopia risk in this small group of children.