Does abnormal head posture aid in amblyopia prevention?

PURPOSE: To assess the prevalence and severity of unilateral amblyopia in patients with ocular abnormal head posture (AHP) and to investigate whether the presence of compensatory head posturing provides protection against the development of amblyopia. METHOD: In this retrospective cross-sectional study, the medical records of 1400 patients with various etiologies of AHP were reviewed. This cohort included individuals with congenital superior oblique palsy (SOP) (n = 758), Duane retraction syndrome (DRS) (n = 582), and Brown syndrome (n = 60), all of whom were candidates for surgical treatment at Farabi Eye Hospital, Iran from 2015 to 2022. Unilateral amblyopia was defined based on the presence of ≥ 2 Snellen line difference in CDVA and CDVA being worse than 0.1 logMAR in the amblyopic eye. RESULTS: The mean ages of patients with congenital SOP, DRS, and Brown syndrome were 12.8 ± 12.9 years, 19.3 ± 11.9 years, and 9.0 ± 7.0 years, respectively. The prevalence of amblyopia among patients with congenital SOP, DRS, and Brown syndrome was 65 (8.6%), 117 (20.1%), and 11 (18.3%), respectively. In the DRS group, patients without AHP had a significantly higher prevalence of amblyopia (26.4%) compared to those with AHP (18.1%) (P = 0.039). However, in the congenital SOP and Brown syndrome groups, there was no significant difference in the prevalence of amblyopia between patients with and without AHP (P > 0.05). There were no significant differences in the horizontal and vertical angles of deviation in primary position between groups of patients with and without AHP or amblyopia across all three ocular pathologies (all P > 0.05). CONCLUSION: The high prevalence of unilateral amblyopia among patients with ocular AHP, despite the presence of compensatory head posturing, indicates that while AHP can aid in maintaining binocular vision, it does not guarantee complete protection against the development of amblyopia.