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Colin Downey, Griffin Pace, Eric Seemiller, Rowan Candy, Larry Cormack; Dynamic Characteristics of 5 to 22 week-old Infants' Accommodation and Vergence Tracking Responses. Journal of Vision 2017;17(10):443. doi: https://doi.org/10.1167/17.10.443.
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© ARVO (1962-2015); The Authors (2016-present)
The motor and sensory binocular visual systems develop dramatically during the first 5 months after birth. Typical development of stereopsis is dependent on adequate image quality and alignment in the dynamic natural environment, requiring appropriate accommodation (A) and vergence (V). This study documented the development of dynamic characteristics of infant accommodation and vergence responses between 5 and 22 weeks of age, using a correlogram approach (Mulligan et al, 2013). Fifteen infants (two excluded due to restlessness) and 10 adult controls were tested during trials in which they viewed naturalistic cartoons presented on a screen. The stimulus moved as a random walk in depth between 33-80cm for 100 seconds. Horizontal eye position and refractive state were recorded binocularly and simultaneously at 50Hz using eccentric photorefraction and Purkinje-image eye-tracking analyses of video images (PowerRef 3, PlusOptix). Cross-correlations of the stimulus and response velocities demonstrated steady maturation of (V) and (A) between 5 and 22 weeks. Adults demonstrated mean peak correlations of 0.80±0.03 for (V) and 0.75±0.10for (A, left eye), at mean time lags of 0.15s±0.04 (V) and 0.20±0.05 (A,left). 5-9 week-olds, 10-13 week-olds and >14 week-olds had mean peak correlations of 0.54±0.17, 0.67±0.11 and 0.60 ± 0.15 (V) and 0.52±0.16, 0.61±0.12, 0.52±0.14 (A,left), at time lags of 0.42s±0.20, 0.25s±0.07, 0.26s±0.11 (V) and 0.36s±0.12, 0.23s±0.07, 0.28s±0.13 (A, left). These data indicate that by five weeks of age, some infants are able to track these unpredictable dynamic stimuli with short delays on the order of only 0.3s (V) and 0.2s (A, left) slower than adults, albeit with more response variability as indicated by reduced peak correlations.
Meeting abstract presented at VSS 2017
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