Longitudinal Assessment of High- and Low-Contrast Visual Acuity in Normally-Sighted Children
John Sollee1, Amy Lavery2, Geraldine Liu2, Maxwell Pistilli3, Gui-Shuang Ying3, Amy Waldman2
1Warren Alpert Medical School of Brown University, 2Child Neurology, Children's Hospital of Philadelphia, 3Biostatistics, Epidemiology and Informatics, Perelman School of Medicine at the University of Pennsylvania
Objective:
To characterize longitudinal visual changes in healthy children.
Background:
Visual acuity (VA) is often used as an outcome measure in clinical and research investigations, although age-related normative contrast data is lacking. We have previously demonstrated in a cross-sectional cohort (ages 5-20 years, grouped by age) that mean monocular and binocular high-contrast visual acuity (HCVA) and monocular low-contrast letter acuity (LCLA) scores increase with age linearly between 5–14 years in normally-sighted youth; however, improvements in acuity scores have not been validated longitudinally in individual children.
Design/Methods:
Children and young adults without neurologic, systemic, or ocular diseases (except refractive error) enrolled in our research program were eligible for longitudinal vision testing. Binocular HCVA and LCLA were assessed at 2 meters using EDTRS and Sloan charts (2.5% and 1.25% contrast). Linear regression with generalized estimating equations to account for repeated observations were used to calculate mean annual visual acuity change.
Results:
Among 101 subjects enrolled in the cross-sectional study, 27 subjects returned for longitudinal testing at a mean of 2.78 years after initial testing. For subjects ≥13 years of age, the mean annual change in binocular scores in letters was -0.67 (p=0.01), -0.82 (p=0.04), and -1.58 (p=0.01) for HCVA, LCLA 2.5%, and LCLA 1.25%, respectively. For subjects <13 years, the mean annual change in binocular scores was 2.31 (p=0.008), 1.71 (p=0.003), and 2.03 (p=0.04) for HCVA, LCLA 2.5%, and LCLA 1.25%, respectively. For all levels of contrast, subjects <7 years of age demonstrated the greatest mean annual changes.
Conclusions:
While HCVA, LCLA 2.5%, and LCLA 1.25% increase annually in children <13 years, scores are expected to remain constant or slightly decrease thereafter. Given variabilities in normal visual acuity changes across the age span, clinicians should use caution when interpreting treatment response or disease progression based on such measures.