The comparative development of movement hyperacuity and visual acuity in children.

Oscillatory movement displacement thresholds (OMDT) have been suggested as a test of neural integrity of the visual system, detecting deficit even in the presence of normal resolution. Both OMDT and visual resolution were measured in 153 normal children between the ages of 2.2 and 13 yr (mean = 6.2 +/- 2.8 yr). OMDT were obtained using a computer-generated vertical bar stimulus oscillating at 4 Hz. Visual acuity was determined using a Polymetric Vision Assessment technique (PVA) where a single letter optotype is presented at increasing viewing distance to determine threshold. OMDT is a hyperacuity at all ages, exhibiting improving thresholds up to around 8 yr of age when results are typical of adults. PVA thresholds improve less markedly over the range measured, appearing mature by 6-7 yr. Correlation between OMDT hyperacuity and visual acuity is poor, illustrating the complexity of the relationship between hyperacuity and resolution functions.