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Vidhyapriya Sreenivasan, Yifei Wu, Sonisha Neupane, Don Lyon, Katie Shulist Connolly, T Rowan Candy; Vergence and accommodation in non-strabismic hyperopic children. Invest. Ophthalmol. Vis. Sci. 2017;58(8):760. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
About 20% of children with significant hyperopia decompensate into refractive esotropia while others with similar refractive error remain aligned (Babinsky & Candy 2013). How does the hyperopic oculomotor system achieve focused and aligned images despite the conflict between accommodation & vergence? Here we compared vergence and accommodation during monocular and binocular viewing between young non-strabismic hyperopic & typically developing children.
Purkinje image tracking & eccentric photorefraction (MCS PowerRefractor, PR) were used to record vergence & refractive state of non-strabismic children (1-9 years) with uncorrected hyperopia (UHY; N=9, Mean cyclo SE=+3.4 D, SD 0.5), partially corrected hyperopia (PCY; N=7, Mean cyclo SE=+5.0 D, SD 2.1; SRx: +3.9 D, SD 1.7) or typical development (TYP, N=11; Mean cyclo SE= +1.0 D, SD 0.8). Children viewed naturalistic targets at 1m & 0.33m in monocular and binocular viewing. Monocular responses were compared between right & left eye viewing & after dissociation of 5s & 30s. Phoria was derived from the difference between binocular & monocular alignment.
There was no difference (mixed model) in accommodative accuracy across groups (p=0.7) (refractive state values at 1m, UHY +0.9 D, SD 0.7; PCY +0.2D, SD 0.2; TYP +0.2 D SD 0.3, and at 0.33m, UHY -1.3D, SD 1; PCY -1.5D, SD 1; TYP -2.0D, SD 0.7). The ratio of change in vergence to accommodation (V:A) showed significantly smaller monocular viewing ratios than binocular ratios (mean diff=0.2MA/D; p=0.00). The hyperopic groups showed lower monocular ratios than the TYP (Mean diff=0.1MA/D), although this difference was not significant (p=0.4). Phoria was also not different on average (p=0.9) between hyperopes and TYP (Exophoria at 0.33m: UHY -1.9 pd, SD 3; PCY -4.3pd, SD 4.5; TYP -2.7pd, SD 3.2). However, we found significant effects of viewing distance (mean 3.2 pd more exophoric at 0.33m, p=0.000) & dissociation time (mean 0.9 pd more exophoric for 30s; p=0.009) on phoria.
These data suggest some hyperopes, who remain binocularly aligned, show simultaneous accommodative & vergence performance comparable to that seen in typically developing children under both monocular & binocular viewing conditions
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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