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Anita Simmers, Pamela Knox, Lyle Gray; Prolonged periods of binocular stimulation can provide an effective treatment in childhood amblyopia. Journal of Vision 2011;11(11):408. doi: 10.1167/11.11.408.
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© ARVO (1962-2015); The Authors (2016-present)
The observation that recovery of visual function in amblyopia is contingent on even brief periods of correlated binocular vision suggests that amblyopia is intrinsically a binocular problem. This has profound implications for the treatment of human amblyopia. An alternative approach to treatment should aim to improve binocularity in addition to monocular visual acuity of the amblyopic eye. Global motion detection using a dichoptic stimulation paradigm was employed to measure the extent of binocular interaction; signal dots were presented to the amblyopic eye while the contrast of the noise dots in the fellow eye was varied. Children then played a simple computer game ‘Tetris’. In the game the falling blocks forming each pattern were presented to one eye and the stationary blocks to the other eye. Previously measured contrast thresholds were used to match the visibility of the blocks in each eye. This arrangement forces the subject to use both eyes to perform the task, whilst minimizing inter-ocular suppression. The children played the game for 1 hour each session with five sessions over the course of a week. Correlations between binocular vision status, degree and type of amblyopia and the dichoptic contrast imbalance for binocular interactions were determined. Overall, the magnitude of the contrast imbalance for binocular summation was found to reduce significantly over the treatment period, concurrent with improvements in traditional logMAR acuity. Interestingly, under natural viewing conditions the improvement in contrast imbalance was reflected in a strengthening of binocularity and the establishment of measurable stereopsis. These results verify the feasibility of the recovery of binocularity in amblyopic children. It can be hypothesized that patients who do not respond to existing treatments and/or show regression in visual function, may obtain an improved and more stable visual outcome with this binocular approach to treatment.
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