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Arvind Chandna, Anthony Norcia, Sylwia Migas; Relative motion loss in high functioning children with Cerebral Visual Impairment (CVI). Invest. Ophthalmol. Vis. Sci. 2017;58(8):4896.
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CVI, characterized by structural damage to the retrochiasmatic visual areas of the brain from a variety of causes in preterm and early life, presents with a spectrum of mild to severe visual and oculomotor dysfunction. Structured history taking from parents of children with mild CVI and near normal visual acuity (VA) reveals behaviorisms suggestive of higher visual function deficits (HVFDs) - these frequently include difficulties with perceiving motion in everyday scenes such being able to see stationary objects while in motion and vice versa (relative motion). These reported HVFDs including motion deficits have not been studied before in this unique sub-population.
35 children (age range 4.4 yrs – 14.4 yrs) with ophthalmic, neurologic and radiologic diagnosis of mild CVI and letter acuity better than 20/40 and 27 visually normal children and (age range 3.70 yrs – 14.53 yrs) participated in the study. We recorded Visual Evoked Potentials (VEPs) with a vernier VEP paradigm (Norcia, Wesemann et al. 1999) as this elicits both position-specific (vernier) responses at the first harmonic (an electrophysiological correlate of optotype acuity) and relative motion responses at the second harmonic. VEP evoked responses were also recorded with a fast jitter stimulus (Shea, Chandna 1999) that gave comparative information on absolute motion responses
VEP Vernier acuity thresholds were equal in the CVI and normal control groups, consistent with their optotype acuity. By contrast, children with CVI showed significant losses of suprathreshold amplitude that were particularly large for the second harmonic (relative motion) component. No differences were seen between neurotypical and CVI children for their responses to absolute motion.
The results suggest selective losses of supra-threshold relative motion responses in children with mild CVI.
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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