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Eric Seemiller, Danielle Teel, Erin Babinsky, Tawna Roberts, T. Rowan Candy; The influence of accommodation and vergence coupling during visual development.. Journal of Vision 2012;12(9):477. doi: 10.1167/12.9.477.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Accommodation (A) and vergence (V) responses are central to coordinating visual experience during development. Infants and young children have a narrower inter-pupillary distance and greater hyperopia than adults. Hence their A & V demands are both immature and vary rapidly with growth. The A & V motor systems are coupled in infancy. Is this coupling protective during development? Methods: Eccentric photorefraction was used to collect A & V responses simultaneously at 25Hz. Their coupling (ACA and CAC ratios) was measured by driving one system with the other open-loop (monocular viewing or a DOG target). A 2D or MA stimulus was used. The amplitudes of the A & V responses were then used to calculate the response ACA and CAC ratio for each subject. Results: Usable data were collected from 19 3-month-olds, 20 3-year-olds and 31 adults. The mean logACA ratios (pd/D) were .52(SD ±.25), .50(±.19) and .68(±.21) at these ages, and the mean logCAC ratios (D/pd) were -.89(±.27), -1.04(±.26) and -1.17(±.24). A PCA revealed 3 significant components that explained 82% of the variance and were interpreted as a reciprocal relationship between the ACA and CAC ratios, the accommodation response to the ACA stimulus and the vergence response to the CAC stimulus. ANOVA was also used to explore the ratios as a function of age. The ACA ratio in pd increased with age (p=.011), while the CAC in pd decreased (p=.002). Conclusions: Accommodative demands are typically increased in infancy and vergence demands are reduced. These data suggest that immaturities in the ACA and CAC ratios are appropriate for these demands in infancy, and that changes in the reciprocal relationship over time characterize the relative changes in demand.
Meeting abstract presented at VSS 2012
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