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Sarah E Morale, Simone Lan Li, Reed M Jost, Angie De La Cruz, David Stager, Lori Dao, Eileen E Birch; Interocular Suppression and Treatment of Childhood Amblyopia. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2197. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
New techniques for measuring depth of interocular suppression make it possible to quantify the relationship between suppression and monocular visual deficits in amblyopia. Here, we investigate the effects of treatment on interocular suppression and its relationship to changes in visual acuity in amblyopic children.
121 children (5-12y) with strabismus, anisometropia, or both were tested; 71 were amblyopic, 24 were never amblyopic, 26 had recovered from amblyopia with treatment. Depth of interocular suppression was measured with a dichoptic motion coherence task. The amblyopic eye viewed high contrast coherent moving dots while the fellow eye viewed randomly moving dots with adjustable contrast. Dichoptic threshold (DT) was defined as the maximum fellow eye percent contrast (%C) that allowed reliable motion direction discrimination determined using a 2-down-1-up staircase protocol. Higher DT values indicate less interocular suppression. Best-corrected visual acuity (BCVA) was measured with ATS-HOTV (5-6y) or e-ETDRS (7-12y).
Mean (± se) DT for strabismic and/or anisometropic children who were never amblyopic was 84±3 %C and for those who had recovered was 69±6 %C. There was no significant difference in DT between strabismic and anisometropic amblyopia (49±5 vs 55±4 %C; p=0.36). DTs for amblyopic children being treated with glasses (45±4 %C) and those being treated with patching + glasses (35±5 %C; p<0.0001) were significantly lower than both nonamblyopic groups (p<0.001). DT for amblyopic children participating in binocular treatment (Li et al Eye 2014; Birch et al JAAPOS in press) was not significantly different from the recovered group (68±6 %C; p=0.90) but was significantly higher than the patching + glasses group (p<0.0001). For 30 children who had 2 visits, including 3 with recurrent amblyopia, 17 with stable BCVA, and 10 with BCVA improvement, the change in DT was correlated with the change in BCVA (r=-0.47; p=0.009).
The success of amblyopia treatment may rely on the remediation of interocular suppression, which plays a key role in strabismic and anisometropic amblyopia. Binocular treatment appears to be more effective than patching in reducing interocular suppression.
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