Contrast sensitivity of patients with severe motor and intellectual disabilities and cerebral visual impairment

We attempt to evaluate the residual visual capacities of nine patients (seven males and two females; age range 4 to 35 years, mean 13.8 +/- 9.98) with cerebral visual impairment coupled with severe motor and intellectual disabilities by their contrast sensitivities to sine-wave gratings. Two methods were used for detecting the occurrence of ocular responses to stimuli: (1) detection of optokinetic nystagmus to drifting sinusoidal gratings by naked-eye observation and electronystagmography and (2) detection of ocular pursuit for a drifting Gabor patch by naked-eye observation. We succeeded in measuring the sensitivities of eight cases. For the remaining one case, only the Gabor method could be applied. Most cases showed low contrast sensitivity in both higher (2 and 4 cycles/degree) and lower (0.125 and 0.25 cycles/degree) spatial frequencies and relatively high contrast sensitivity in the middle (0.5 and 1 cycle/degree) range of spatial frequencies. We conclude that the residual visual capacities of patients with severe motor and intellectual disabilities and cerebral visual impairment can be measured fairly accurately by these behavioral methods.