Efficacy of occlusion for strabismic amblyopia: can an optimal duration be identified?

Abstract

Background/aims-The study of occlusion eYcacy in amblyopia has been hampered by the use of non-logMAR acuity tests and a failure to assess threshold acuity for both eyes. These issues are addressed in the current study which compares the eVect of spectacles alone and spectacles in combination with occlusion, with the use of the logMAR crowded test. Methods-Changes in uniocular and interocular acuity diVerences were compared for two age matched groups of previously untreated children with strabismic amblyopia: one compliant with spectacles only (n = 17, mean 6.2 (SD 2.5) years) and the other with spectacles and occlusion (n = 69, mean 5.1 (1) years) over a 1 year period. Changes in logMAR acuity were also analysed for a larger occluded group (n = 119) in response to successive 200 hour blocks of occlusion up to >1000 hours, in an attempt to isolate an optimal occlusion regime. Results-Visual acuity improved for more of the amblyopic eyes of the occluded (74%) than the spectacles only group (59%), and only one child from the latter group deteriorated. Mean visual acuity improved for both eyes of both treatment groups, but the change was significantly larger for the strabismic eyes of the occluded group overall and within the first 6 month period (p <0.05). Occlusion was only eVective for the first 400 hours worn. Subsequent visual improvement was bilateral and symmetrical.Conclusion-Occlusion is more eVective in the treatment of strabismic amblyopia than spectacles alone, and the eVect is optimal within the first 6 months of wear. In terms of occlusion duration, maximal improvement occurs in response to 400 hours of occlusion wear or less, and to full time occlusion. Visual maturation continues, but is retarded for amblyopic eyes. (Br J Ophthalmol 2000;84:572-578) Amblyopia aVects 2-3% of the population, and strabismus, often associated with anisometropia, is a major cause.

Adesão ao tratamento da ambliopia

“…A oclusão realizada em 100 crianças amblíopes, com idade entre 7 e 12 anos, resultou em ganho para cerca de 68% delas (14) , o que reforça a nossa idéia. Além da idade da criança, o resultado do tratamento pode também ser influenciado pela causa da ambliopia (15) , sendo a oclusão mais efetiva nos portadores de ambliopia estrabís-mica (16) .…”

“…A avaliação do tempo de tratamento para melhora mostrou que, mesmo que haja colaboração, há necessidade de tempo prolongado para se obter melhora, já havendo sido previamente relatado tempo de 6 meses para os efeitos da oclusão serem sentidos (16) .…”

Assessment of a computer-based treatment for older amblyopes: the Glasgow Pilot Study

“…[8][9][10][11][12][13][14] Patching can cause social stigma, and have a detrimental impact on family, school, and social life. 12,15,16 Although most of the treatment effect probably occurs within the first 120-200 h or 6 weeks of patch wear, 17,18 in normal clinical practice, patching can continue for many months or years, 17,19 placing considerable demands on the child and family.…”

Modified virtual reality technology for treatment of amblyopia

“…Parents often find patching difficult to implement, children dislike the treatment as the patches are uncomfortable to remove, result in poorer vision while the good eye is patched, and the child often feels stigmatised. In addition occlusion therapy can be prolonged, sometimes lasting more than a year, 2 and patching cannot improve binocular cooperation. 3 Our aim was to develop an amblyopia treatment which allows both eyes to be used at the same time, thus improving visual acuity in an enjoyable format for children.…”