Factors affecting the stability of visual function following cessation of occlusion therapy for amblyopia

Aim To identify factors that predict which children with amblyopia are at greatest risk of regression of visual acuity (VA) following the cessation of occlusion therapy. Method A retrospective analysis was performed of 182 children (mean age at cessation of treatment; 5.9±1.6 years) who had undergone occlusion therapy for unilateral amblyopia, and had been followed up at least once within 15 months of cessation. Statistical analysis was used to identify whether change in VA following treatment cessation had any association with various factors, including the child’s age, type of amblyopia, degree of anisometropia, initial severity of amblyopia, binocular vision status, length and dose of occlusion therapy, and VA response to treatment. Results At 1 year, follow-up from treatment cessation, children with “mixed” amblyopia (both anisometropia and strabismus) demonstrated significantly (p=0.03) greater deterioration in VA (0.11±0.11 log units) than children with only anisometropia (0.02±0.08 log units) or only strabismus (0.05±0.10 log units). However, none of the other factors investigated were found to be significant predictors. Conclusion This study supports previous research that it is possible to identify those children most at risk of deterioration in VA following cessation of occlusion therapy. The presence of mixed amblyopia was the only risk factor identified in this study. Management of amblyopia should take this into account, with a more intensive follow-up recommended for those with both anisometropia and strabismus (mixed) amblyopia.