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C.E. Stewart, A.R. Fielder, M.J. Moseley, D.A. Stephens, MOTAS Cooperative; Visual Function of Children with Amblyopia During Refractive Adaptation and Occlusion Therapy . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4245.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To examine the changes in visual function during refractive adaptation and occlusion in the Monitored Occlusion Treatment for Amblyopia Study (MOTAS). Methods: Data were obtained from 94 subjects (mean age = 5.1 ± 1.4 years) with amblyopia associated with strabismus (n=34), anisometropia (n=23), and with both anisometropia and strabismus (n=37). Eighty-six subjects required refractive correction and underwent 18 weeks of spectacle wear ('refractive adaptation'). Those subjects whose amblyopia persisted were prescribed 6 hours of occlusion per day. Outcome variables (logMAR visual acuity, log letter contrast sensitivity (Pelli-Robson)) were assessed at six-weekly intervals during refractive adaptation and at two-weekly intervals during occlusion until gains in visual function ceased to be statistically verifiable. Patch wear was objectively recorded using an occlusion dose monitor (Fielder AR, et al. Lancet, 1994;343:547). Results: Mean visual acuities in amblyopic eyes at the start and end of refractive adaptation were 0.69 ± 0.38 and 0.44 ± 0.42 logMAR respectively. Mean letter contrast sensitivity in amblyopic eyes at the start and end of refractive adaptation were 1.46 ± 0.29 and 1.61 ± 0.12 log units respectively. Thirteen subjects who gained normal visual acuity during this phase were not occluded. Mean visual acuities in amblyopic eyes at the start and end of occlusion were 0.5 ± 0.35 and 0.2 ± 0.25 logMAR respectively. Mean letter contrast sensitivity in amblyopic eyes at the start and end of occlusion were 1.60 ± 0.13 and 1.65 ± 0.07 log units respectively. Visual acuity in the fellow eyes at the start and end of treatment was 0.15 ± 0.13 and 0.02 ± 0.1 logMAR respectively. Mean letter contrast sensitivity in fellow eyes at the start and end of treatment was 1.63 ± 0.05 and 1.65 ± 0.03 log units respectively. Conclusion: Refractive adaptation is a distinct component of amblyopia treatment, the benefits of which should be fully differentiated from those of occlusion in order that their relative contributions can be evaluated. In practice, this means that children may start occlusion with improved visual acuity, possibly enhancing compliance, and in some cases unnecessary patching will be avoided. Amblyopes reach normal or near normal levels of letter contrast sensitivity after 18 weeks' refractive adaptation while visual acuity in most cases remains significantly reduced. The fellow eye of unilateral amblyopes can be expected to demonstrate a small improvement in visual acuity during treatment.
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