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Anna M. Horwood, Sonia Toor, Patricia Riddell; Fully Accommodative Esotropes Use Disparity Less And Blur More. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6352.
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© ARVO (1962-2015); The Authors (2016-present)
Fully accommodative esotropia (FA) is controlled to binocular single vision when hyperopia is corrected, but some children with similar hyperopia do not become strabismic. We predicted that fully accommodative esotropes would show more response to blur cues, and less to disparity, when compared to emmetropes and non-squinting hyperopes.
11 children with FA aged 4-8 years, 9 age- and refraction-matched non-squinting hyperopes (HYP) and 27 age-matched emmetropic typically developing children (TD) were assessed. All children wore full hyperopic correction for testing and all had equal visual acuity and at least 60" stereoacuity when corrected. Children with microtropia were excluded. Vergence and accommodation were assessed with a PlusoptiXSO4 photorefractor set in a haploscopic device. Target manipulations presented all combinations of blur(b)/disparity(d) and proximity(p) cues at four distances between 33cm and 2m.
Accommodation: FAs showed more accommodative lag at 33cm across all cues than TDs (p=0.019). Removing blur cues reduced the accommodation response gain more in FA than in TD (p=0.05).Vergence: Vergence gain to the blur-only target was greater in FA than in both TD (p=0.001) and HYP (p=0.007). Vergence gain was also less disrupted by removing disparity (bp target) than in TD (p=0.001).
Fully accommodative esotropias showed more accommodative lag to all targets than TD or HYP despite full hyperopia correction. FA accommodation is more disrupted by removing blur cues. Differences between cue conditions were more evident for vergence than accommodation. FA vergence was less disrupted by removing disparity cues, and their vergence responses were better to blur cues than TDs. The vergence of fully accommodative esotropes is more responsive to blur and somewhat less responsive to disparity cues despite the significant accommodative lag. We suggest that blur is more highly weighted, and disparity less weighted in FA in comparison to typical or non-squinting hyperopic children. In young children this atypical weighting may predispose to strabismus.
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