Twelve patients (17 eyes) with the acute retinal necrosis syndrome were analyzed with special reference to the development of an acute optic neuropathy. Six patients (9 eyes) without acute optic nerve involvement were treated with intravenous acyclovir sodium and/or vitreoretinal surgery (group 1). Six patients (8 eyes) fulfilling absolute and relative criteria for acute retinal necrosis optic neuropathy were treated with intravenous acyclovir as well as optic nerve sheath decompression, and, in addition, some of these patients also underwent vitreoretinal surgery. Despite more pronounced initial visual loss compared with group 1, six eyes in group 2 regained visual acuity of 20/400 or better. In contrast, only 2 of 9 eyes in group 1 maintained their entry level visual acuity, and the visual acuities of the remaining 7 eyes deteriorated to counting fingers or worse. Therefore, the acute optic neuropathy complicating the acute retinal necrosis syndrome appears to benefit from prompt recognition and surgical decompression of the intraorbital optic nerve meninges in conjunction with intravenous acyclovir.