Abstract
Abstract: :
Purpose: The MTI Photoscreener, based on the principle of eccentric photorefraction, captures the retinal reflex onto Polaroid film. We correlated the level of hyperopia to the dimension of the crescent in children. Methods: The photographs of 955 participants under 5 years of age from two previous studies were measured for pupillary diameters and bright crescent dimensions. Each child received a complete eye examination. The dark crescent dimension was calculated and as the difference between the pupil diameter and the bright crescent dimension. Each crescent measurement was compared to the magnitude of the refractive error at the corresponding meridian. Receiver operating characteristic (ROC) curves were plots of (1-specificity) vs. sensitivity values, at a range of thresholds for screening failure. Results: We determined how the following characteristics are correlated to sensitivity and specificity detection of hyperopia: bright crescent vs. dark crescent dimensions, presence vs. absence of bright crescents, and the sizes of pupils. In comparing the correlation of bright vs. dark crescent dimensions to the degree of hyperopia, the corresponding ROC curves were not significantly different. However, the presence of a bright crescent improved the dark crescents’ correlation to suprathreshold refractive error. More favorable ROC plots were associated with pupils ≷ 6mm. Conclusion: Detection of hyperopia with the MTI PhotoScreener will yield superior results when the pupillary diameter is greater, or when a bright crescent is present. The theoretical advantage of dark crescents does not carry over into practice. The results suggest that ambient lighting should be dimmed to achieve pupil diameters of ≷ 6mm. CR: None
Keywords: 313 amblyopia • 427 hyperopia • 519 physiological optics