Predicting the Progression of Early Onset Myopia

Abstract

Purpose: : In a previous study, we showed that early onset myopia was associated with an increased variability in accommodation. However, we were not able to determine the causal relationship between increased variability of accommodation and myopia. We have conducted a 2-year follow up study to investigate the predictive effect of accommodative variability on refractive status.

Methods: : Twenty-three participants returned for testing (9 emmetropes, 14 myopes, all ≤15 years at initial visit). Participants were grouped both by their refractive status at the initial visit and on refractive status at the follow up visit. Measures of accommodation were made using an eccentric infrared autorefractor, the PowerRefractor, in dynamic mode. The refractive status of the eyes was recorded dynamically at a frequency of 0.25Hz. The children were instructed to focus on highly accommodative targets set at three different distances (accommodative demands of 0.25, 2 and 4 D). Each target was tested twice in a pseudo-random sequence.

Results: : When grouped on refractive error at the initial visit, there was no difference in accommodative lag between groups, but a significant difference in accommodative variability between groups at the initial visit: F_{1, 54} = 4.78, p = 0.033. When participants were grouped on the basis of their refractive error at the follow up visit, there were significant differences between groups in both accommodative lag and accommodative variability at the initial visit: F_{1, 52} = 4.04, p = 0.05 and F_{1, 52} = 4.74, p = 0.034 respectively.

Conclusions: : While accommodative variability was increased in our early onset myope group at initial testing, accommodative lag was not found to be greater. In comparison, both accommodative variability and accommodative lag were greater at initial testing when participants were grouped by myopia at the follow up visit. We believe that these variables have some predictive value in determining myopic progression.

Keywords: refractive error development • myopia • accomodation