Unilateral syphilitic optic perineuritis presenting as the big blind spot syndrome.

Unilateral swelling of the optic nerve head in the absence of demonstrable optic nerve dysfunction (the big blind spot syndrome) has been described as an idiopathic self-limited phenomena. We report two patients who manifested this syndrome due to syphilitic optic perineuritis. Although unilateral syphilitic optic neuritis has been well described, optic perineuritis has been described previously only as a bilateral condition. The cases emphasize the need to consider syphilis in conditions affecting the optic nerve either unilaterally or bilaterally with or without an associated optic neuropathy.