Abstract
Abstract: :
Purpose: To determine the dose-response relationship for occlusion therapy. Methods: Data were obtained from 57 children (mean age 5.1 1.4 years) with amblyopia associated with strabismus (n=22), anisometropia (n=15), and with both anisometropia and strabismus (n=20). Forty-eight required refractive correction and wore spectacles for 18 weeks before starting occlusion. All subjects were prescribed 6 hours occlusion/day. Outcome variables (logMAR visual acuity, log contrast sensitivity and stereoacuity) were assessed at two weekly intervals until gains in visual acuity ceased to be statistically verifiable. Occlusion was objectively recorded using an occlusion dose monitor (Fielder AR, et al. Lancet, 1994;343:547). Results: Mean visual acuities at onset and end of occlusion were 0.53 0.36 and 0.26 0.16 logMAR respectively. Approximately 85% of the improvement in visual acuity occurred in the first 6 weeks of occlusion. Children ≤5 years showed a greater improvement (change in VA: 0.39 log units vs. 0.12 log units) than children ≷ 5 years (P<0.01). The relationship between the gain in visual acuity and total occlusion dose was described by a monotonic function, which for all categories of amblyopia appears to be linear up to 160 hours of total recorded dose. In this linear phase, visual acuity is observed to improve, on average, by 0.1 log units per 40 hours of occlusion dose. Conclusion: Occlusion therapy is most effective in the first few weeks of treatment with outcome positively correlated with dose and age. We provide the first quantitative description of the dose-response relationship for occlusion therapy.
Keywords: 313 amblyopia • 357 clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials