Comparison of binocular reading speed in patients with strabismus without amblyopia versus controls

Amblyopia has been shown to slow reading speed. Limited literature exists on reading speed in strabismus without amblyopia. Our study compares binocular reading speed in patients with strabismus without amblyopia versus normal controls.

We conducted a prospective study with 48 participants: 12 childhood-onset (onset <8 years of age) strabismus without amblyopia and 36 age- and education level-matched controls. Inclusion criteria were age 14-50 years, education >9 years, primary language English, best-corrected visual acuity >20/30 distance, and >N8 near either eye. Exclusion criteria were presence of other eye pathology or neurologic/cognitive conditions that may affect reading and previous treatment for strabismus/amblyopia. International Reading Speed Texts were used for binocular reading speed assessment. Each participant read 2 passages (passage 1 and 8), following all International Reading Speed Texts instructions. Reading time was measured using a stopwatch. Reading speed was calculated in words per minute (WPM).

Mean age for the strabismus group was 28.3 ± 11.1 and for the control group was 28.2 ± 11.0 years (P = 0.96). Mean education level for strabismus group was 14.2 ± 2.4 and control group was 13.8 ± 2.5 years (P = 0.62). Mean binocular reading speed for passage 1 for strabismus group was 192.0 and for control group was 220.0 WPM (P = 0.01). Mean binocular reading speed for passage 8 for strabismus group was 201.3 and for control group was 226.2 WPM (P = 0.04).

Patients with strabismus (without amblyopia) had slower binocular reading speed compared with controls. Further studies with eye tracking may provide more information. Strabismus, even without amblyopia, may affect reading performance and consequently vision-related quality of life.