Positive occipital sharp transients of sleep in the blind.

Positive occipital sharp transients of sleep (POSTS) were evaluated in 23 legally blind subjects. Only those subjects with severe visual field defects but normal or near normal visual acuity showed this activity. Nineteen subjects with visual acuity of 20/200 or worse failed to exhibit these potentials, while a control group matched for age showed POST in 79 percent of cases. The production of POSTS appears to depend on the integrity of macular function and normal central visual acuity.