Visual Acuity Outcomes in a Randomized Trial of Wavefront Metric-optimized Refractions in Adults with Down Syndrome

This study reports visual acuity outcomes from a clinical trial investigating an objective refraction strategy that may provide a useful tool for practitioners needing additional strategies to identify refractive corrections for adults with intellectual disability.

Determining refractions for individuals with Down syndrome is challenging because of the presence of elevated refractive error, optical aberrations, and cognitive impairment. This randomized clinical trial evaluated the performance of spectacle corrections determined using clinical techniques and objective refractions derived from wavefront aberration measures.

Thirty adults with Down syndrome had a clinical refraction determined by a single expert examiner using pre-dilation and post-dilation techniques appropriate for this population. Objective refractions were determined from dilated wavefront aberration measures that were processed post-visit to identify refractions that optimized each of two image quality metrics: pupil fraction tessellated and visual Strehl ratio in the spatial domain. The three refractions were dispensed in random order and worn for 2 months each. The primary outcome measure, binocular visual acuity, was obtained by a masked examiner administering a distance logMAR acuity test. To compare treatment types, mean acuity was compared using a two-sided type 3 F test of the treatment effect in a linear mixed-effects regression model, where the final model included fixed effects for treatment, period (1, 2, or 3), and first-order carryover effects.

The 2-month estimated least square means in binocular visual acuity (logMAR) were 0.34 (95% confidence interval [CI], 0.25 to 0.39) for clinical refractions, 0.31 (95% CI, 0.25 to 0.36) for pupil fraction tesselated refractions, and 0.33 (95% CI, 0.27 to 0.38) for visual Strehl ratio refractions. No statistically significant treatment effect was observed (F = 1.10, P = .34).

Objective refractions derived from dilated wavefront aberration measures resulted in acuity similar to expert clinician-derived refractions, suggesting that the objective method may be a suitable alternative for patients with Down syndrome.