Abstract
Purpose :
Determining refractive corrections for individuals with Down syndrome (DS) is challenging due to the presence of elevated refractive error, optical aberrations, and cognitive impairment. This randomized clinical trial evaluated performance of spectacle corrections determined using clinical techniques versus objective refractions derived from wavefront aberration measures.
Methods :
Thirty adults with DS received a comprehensive eye examination during which clinical refraction was determined by a single expert examiner experienced in examination of individuals with special needs using techniques appropriate for this population. To determine objective refractions, dilated wavefront aberration measures were obtained and processed post-visit to identify refractions based on the optimization of each of two image quality metrics: pupil fraction tessellated (PFSt) and visual Strehl ratio in the spatial domain (VSX). The three refractions were dispensed in random order in an identical spectacle frame selected by the participant. The primary outcome measure, binocular visual acuity, was obtained after 2 months of wear for each prescription type by a masked examiner administering a distance logMAR acuity test. To compare treatment types, mean acuity was compared using a 2-sided Type 3 F-test of the treatment effect in a linear mixed-effect regression model, where the final model included fixed-effects for treatment, period (1, 2, or 3), and first order carryover effects.
Results :
The two-month estimated least square means in binocular visual acuity (logMAR) was 0.34 (95% CI: 0.25, 0.39) for clinical refraction, 0.31 (0.25, 0.36) for PFSt, and 0.33 (0.27, 0.38) for VSX. No statistically significant treatment effect was observed (F=1.10, p=0.34).
Conclusions :
Objective refractions derived from wavefront aberration measures resulted in acuity similar to expert clinician derived refractions, suggesting the objective method may be a suitable alternative for patients with DS. Further study with younger patients is warranted to determine if improvements in acuity may be obtained when objective refractions are dispensed to patients with greater neural plasticity and less likelihood of long-standing amblyopia.
This is a 2021 ARVO Annual Meeting abstract.