Comparing latent strabismus in children according to literacy-based learning difficulty status: a prospective study

Purpose: To compare the ocular alignment of children with literacy-based learning difficulties to at-level peers. Methods: Australian primary-school-aged children were recruited to two groups according to learning difficulty status: at-level group (ALG and learning difficulties group (LDG). Cover test, prism, and alternate cover test, convergence near point, accommodation, fusional ranges, near and distance visual acuity, stereoacuity, and ocular motility were assessed at a single visit in 2023. Results: Eleven children (aged 7 to 12 years, 68.2% female) were recruited in each group. A latent deviation of small angle was observed at near in 81.8% (n = 9, median -3.1 PD) of children in the learning difficulties group but only 36.4% (n = 4, median -0.4 PD) in the at-level group (p = .080). The absolute magnitude of deviation for near was also larger in the LDG (n = 11, 6 PD) than the ALG (n = 11, 0 PD, p = .055). Reduced accommodative near point binocularly (p = .024), stereoacuity at near (p = .009), and near vision (oculus dexter [OD] p = .010, oculus sinister [OS] p = .053) were observed in the learning difficulties group. Conclusions: Latent deviations may be more prevalent among children with literacy-based learning difficulties. Accommodative near point, stereoacuity, and near vision may be reduced in this patient cohort. The differences found between the groups in this study indicate that clinicians should include assessment of accommodation, near vision, stereoacuity, and eye position when testing the vision and binocular vision of children with literacy-based learning difficulties.