Comparing visual acuity and optimized visual image quality for individuals with and without Down syndrome

Individuals with Down syndrome experience reduced visual image quality compared with individuals without Down syndrome, even when wearing spectacle prescriptions that have been optimized to maximize visual image quality.

Individuals with Down syndrome are known to have reduced visual acuity; however, it is unknown whether their visual image quality is proportionately reduced. The purpose of this study was to evaluate optimized image quality via visual Strehl ratio (VSX), a measure of visual image quality known to be correlated with visual acuity, in a group of individuals with Down syndrome, and compare the optimized logVSX values to those predicted from a cohort of individuals without Down syndrome.

Wavefront aberration measures were recorded on 30 adults with Down syndrome (age = 29 ± 10 years). A computer program was used to mathematically apply more than 20,000 sphero-cylindrical refractions to the uncorrected wavefront error of each eye. The residual wavefront error was then used to calculate optimized logVSX for each eye. These optimized logVSX values were compared with predicted age and pupil-matched normal levels of optimized logVSX. The logMAR visual acuity measured from individuals with Down syndrome wearing optimized corrections was compared with normative values in the literature for the typical population.

Optimized logVSX values were significantly poorer for individuals with Down syndrome (average: -0.56 ± 0.19) compared with the minimum (average: -0.47 ± 0.12) or mean (average: -0.26 ± 0.10) values predicted in the typical population. Visual acuity in this group of individuals with Down syndrome was also reduced compared with normative values, and there was a significant relationship between visual acuity and optimized logVSX (p=0.03), though with a modest correlation, suggesting that other factors likely also contribute to reduced visual acuity.

Individuals with Down syndrome have reduced logVSX values compared with individuals without Down syndrome.