Accommodative balance in clinical versus metric-optimised prescriptions for adults with Down syndrome

Wavefront-guided objective refractions can be a useful tool for optimising refractions for patients who may have difficulties with subjective refraction. Since these objective refractions are monocularly derived, information about the binocular balance to accommodation is important when clinicians consider prescribing with this method.

Wavefront-guided objective refractions have been investigated in patient populations that have highly aberrated optics and/or difficulty with subjective input, such as people with Down syndrome (DS). However, these objective refractions are determined for each eye individually, unlike a subjective refraction that considers both eyes. This study aimed to compare the interocular balance between objective and subjective prescriptions for adults with DS.

Thirty adults with DS (age 29 ± 10 yrs) were enrolled in a trial to compare performance of clinical refraction versus refractions optimising visual Strehl ratio (VSX) and pupil fraction tessellated (PFS_t) metrics from analysis of dilated wavefront measures (21 participants used for analysis). Visual acuity (VA) via a logMAR-style chart and accommodative lag via MEM retinoscopy were measured. Absolute differences and Pearson correlations for VA and lag were calculated between the eyes of each participant. Repeated measures ANOVA was used to compare inter-eye differences by refraction type.

Mean right eye VA ranged from 0.32 ± 0.17 logMAR to 0.38 ± 0.18 logMAR (p = 0.06) and mean inter-eye difference ranged from 0.09 ± 0.06 logMAR to 0.09 ± 0.10 logMAR (p = 0.98) across correction types. Mean right eye lag ranged from 1.31 ± 0.52D to 1.38 ± 0.68D (p = 0.89) and mean inter-eye difference ranged from 0.15 ± 0.29D to 0.31 ± 0.37D (p = 0.09) across correction types. Left and right eye VA and lag were positively correlated.

Inter-eye differences in VA and accommodative lag were not clinically meaningfully different for any experimental refraction, indicating each refraction was similarly balanced.