Acute idiopathic blind spot enlargement. A big blind spot syndrome without optic disc edema
W. A. Fletcher, R. K. Imes, D. Goodman and W. F. Hoyt
Department of Neurological Surgery, School of Medicine, University of California, San Francisco 94143.
We examined seven patients who had a syndrome of symptomatic monocular
blind spot enlargement without optic disc edema. Two patients had previous
blind spot enlargement that resolved over several months. The scotoma in
each patients was absolute, measured 15 degrees to 20 degrees in diameter,
had steep geographic margins, and extended to within 5 degrees to 10
degrees of fixation. Typically, patients had normal visual acuity, color
vision, pupillary responses, and ophthalmoscopic findings. Photostress
recovery, tested in two patients, was prolonged in the affected eye.
Fluorescein angiography showed no abnormalities corresponding to the
scotoma. Orbital computed tomographic scans in three patients and visual
evoked responses in one patient were normal. Multifocal
electroretinography, performed in two patients, showed loss of retinal
waveforms in a large region surrounding the optic disc. Our findings
suggest that retinal dysfunction produces this big blind spot syndrome, but
we do not know its cause.
