Abstract
Purpose:
Global motion perception is a function of area V5 within the dorsal visual stream and may be a biomarker for abnormal visual cortex development. The use of global motion perception to assess dorsal stream function assumes this ability is relatively independent of functions related to V1 such as contrast sensitivity and visual acuity. In this prospective, observational study we tested this assumption by assessing the relationships among global motion perception, contrast detection thresholds for the global motion stimulus and visual acuity in a cohort of children with perinatal risk factors.
Methods:
One hundred and seventeen 4.5-year-old children who were enrolled in the CHYLD (Children with Hypoglycemia and Later Development) or IDEAL (Infant, Development, Environment and Lifestyle) studies participated. All children were born with at least one of the following risk factors: small for gestational age, large for gestational age, babies of diabetic mothers, or prenatal drug exposure. Motion coherence thresholds (MCT), a measure of global motion perception, were measured using random-dot-kinematograms (100 dots, speed 6 deg/sec). The contrast of the stimuli was fixed at 100% and coherence was varied using a 2-down-1-up staircase. Contrast detection thresholds (CDT) were measured for the same stimuli, whereby motion coherence was fixed at 100% and dot contrast was varied. Visual acuity (crowded Lea symbols / Keeler LogMAR test) and stereopsis (stereo fly test) were also measured.
Results:
MCT and CDT were not significantly correlated (rho=0.04, p=0.5). Children with both the best and poorest MCTs (threshold values in the first and fourth quartiles, respectively) had similar CDTs (p = 0.8). MCT was also not correlated with visual acuity (rho=0.005, p=0.9). However, MCT was moderately but significantly correlated with stereoacuity (rho=0.36, p<0.001). A weak but statistically significant correlation between CDT and visual acuity (rho=0.26, p=0.004) was observed, suggesting a partial relationship between these two measures of spatial vision.
Conclusions:
Global motion perception for high contrast stimuli appears to be independent of contrast detection thresholds and visual acuity in children born with developmental risk factors. This suggests that global motion perception can be used to assess the function of dorsal extra striate visual areas.