Dichoptic Amblyopic Eye Visual Acuity Deficits Limit Visuomotor Skills

Dichoptic amblyopic eye (AE) best-corrected visual acuity (BCVA) deficits are associated with compromised stereoacuity, suppression, and eye-hand coordination and slower reading speed, according to a study published in the American Journal of Ophthalmology. They are worse than monocular AE BCVA deficits in children with amblyopia and children with a history of amblyopia who recovered normal visual acuity with treatment, according to the report. 

Researchers enrolled a total of 96 children (mean age 9.6±1.7 years, 53% girls) in the cross-sectional analysis including patients with amblyopia, (AE BCVA 0.2-0.5 logMAR, n=42), children with a history of amblyopia who recovered to normal vision after treatment (n=24, AE BCVA <0.1 logMAR), and participants with normal vision and no amblyopia history (n=30). They evaluated reading speed, manual dexterity, and ball handling skills and performed Randot preschool stereoacuity and stereo butterfly tests.

Among participants with amblyopia and children who recovered, 48% and 29% had anisometropia, 21% and 50% had strabismus, and 31% and 21% had both, respectively.

Investigators determined that 81% of children with amblyopia and 71% of children with recovered AE BCVA had worse dichoptic than monocular AE BCVA (mean difference 0.15±0.11 and 0.20±0.17 logMAR, respectively; P <.001 for both). They did not observe statistically significant differences among control group participants.

Dichoptic AE BCVA correlated with aiming and catching (r=0.65; P =.0008), stereoacuity (r=0.52; P =.0004), and contrast balance index (r=0.52; P =.0004) and monocular AE BCVA weakly correlated with stereoacuity (r=0.35; P =.02) and contrast balance index (r=0.38; P =.02).

“Dichoptic AE BCVA deficits were worse than monocular AE BCVA deficits and were associated with reduced stereoacuity and suppression, consistent with the hypothesis that binocular dysfunction plays a role,” according to the investigators. “Further, impaired eye-hand coordination and slow reading were associated with dichoptic, but not monocular, AE BCVA. Some children with amblyopia may benefit from extra time for school tasks requiring eye-hand coordination or reading.”

Study limitations include the potential for geographic bias, a lack of randomization in testing order, and the strict inclusion of children with AE BCVA of 20/60 or better.

Reference

Birch EE, Jost RM, Hudgins LA, Morale SE, Donohoe M, Kelly KR. Dichoptic and Monocular Visual Acuity in Amblyopia. Am J Ophthalmol. Published online June 20, 2022. doi:10.1016/j.ajo.2022.06.002