Boston Amblyopia Study 2: Treatment Outcomes in Patients with Asymmetric, Bilateral Amblyopia
Talia N. Shoshany, BA; Suzanne M. Michalak, MD; Kaila M. Bishop, OC(C), MSc; David G. Hunter, MD, PhD
Boston Children’s Hospital
Introduction: Many bilateral amblyopia patients have asymmetric visual acuity (VA). There is no standard treatment protocol for these patients, and outcomes have not been well described.
Methods: Retrospective chart review of 4096 patients evaluated for amblyopia at a teaching hospital between 2010-2015. Inclusion criteria for asymmetric bilateral amblyopia: interocular difference (IOD) ≥0.14 logMAR; VA ≥0.30 bilaterally; minimum 2 visits. Statistical analysis was performed using Wilcoxon signed-ranked test within groups and t-test and chi-squared test between groups.
Results: Of 642 patients reviewed to date, 82 (12.8%) met bilateral amblyopia inclusion criteria; 34 had asymmetric amblyopia. Most received glasses (82%) and nearly half of asymmetric patients (44%) were prescribed occlusion averaging 2 hours/day. Initial VA did not differ significantly between groups (0.40-0.45 in stronger eye; 0.79-0.82 in weaker eye), nor did mean initial IOD (occlusion: 0.40; no-occlusion: 0.37, p=0.7) or mean follow-up (occlusion: 2.7y; no-occlusion: 3.1y, p=0.5).
Occlusion did not result in significant additional improvement in IOD (0.22 improvement with occlusion vs. 0.19 without, p=0.7). Likewise, VA improved similarly in both groups (0.24 VA in stronger eye with occlusion vs. 0.30 without; 0.45 VA in weaker eye with occlusion vs. 0.53 without, p=0.3). Asymmetry resolved to <0.14 in both groups (occlusion: 53.3%; non-occlusion: 52.6%, p=0.9).
Discussion: For bilateral, asymmetric amblyopia, VA improved two lines in both eyes while VA asymmetry resolved in half of patients, regardless of whether occlusion was prescribed.
Conclusion: In patients with asymmetric bilateral amblyopia, occlusion provides no further benefit to spectacle correction alone, nor does it hinder VA improvement in the stronger eye.
References: 1. Klimek, D et al. ‘Isoametropic amblyopia due to high hyperopia in children.’ Journal of American Association for Pediatric Ophthalmology and Strabismus. 2004 August; 8(4): 310-3.
2. Wallace, D et al. ‘Treatment of bilateral refractive amblyopia in children three to less than 10 years of age.’ American Journal of Ophthalmology. 2007 October; 144(4): 487-96.