Reading ability in children with intermittent exotropia and its association with binocular visual function and visual information processing capability.

Purpose: To evaluate children's reading performance with intermittent exotropia (IXT) and investigate possible associations among reading abnormalities, binocular visual function, and visual information processing.

Methods: This cross-sectional, case-control study involved 61 children with basic-type IXT and 40 healthy controls aged 7 to 13. Reading performance was assessed objectively using the Development Eye Movement (DEM) test and subjectively with the Dyslexia Checklist for Chinese Children (DCCC). Binocular visual function assessments included fusion, stereopsis, and contrast sensitivity. Visual information processing was evaluated using the Test of Visual Perceptual Skills (TVPS-4) and Beery Visual Motor Integration (VMI-6).

Results: Children with IXT exhibited significantly poorer performance on both the horizontal (p = 0.04) and vertical subtests (p = 0.048, p = 0.023, p = 0.037 under different viewing conditions) of the DEM test compared to controls. DCCC questionnaire responses indicated greater difficulties among children with IXT in reading, oral language, written expression, reading habits, attention, and vocabulary comprehension (all p < 0.05). Additionally, children with IXT demonstrated significantly reduced stereopsis, fusion, and contrast sensitivity (all p < 0.05). Scores for visual perception (assessed with TVPS-4) and visual-motor integration (assessed with VMI-6) were also lower in the IXT group (p = 0.003 and p = 0.008, respectively). Stepwise multivariate analysis identified visual-motor integration as an independent predictor of DEM reading performance (p = 0.005), accounting for 11% of the variance in reading ability among children with IXT.

Conclusion: Children with intermittent exotropia exhibit reduced reading performance, with visual-motor integration possibly as a key factor. Clinical interventions may benefit from focusing on enhancing visual-motor integration.