Atypical retinitis pigmentosa masquerading as a nerve fiber bundle lesion.

"Sector" or "asymmetric" retinitis pigmentosa was mistaken as bilateral nerve fiber bundle defects in a 56-year-old man for six years, leading to an unnecessary work-up for anterior visual pathway disease and to an incorrect diagnosis of low-tension glaucoma. Confusion arises because this variant may present with bilateral, superior, half-ring visual field defects that intersect the blindspots. These defects may be misplotted as typical arcuate Bjerrum's scotomas. The ophthalmoscopic changes that correspond to these visual field defects may be so subtle as to be overlooked. Fluorescein angiography helps bring out the retinal lesions, and moderately subnormal electroretinographic and dark adaptation studies are definitive.