A Noteworthy Case of Bilateral Idiopathic Optic Perineuritis With No Perception to Light Eye

The aim of this study is to report an interesting case of bilateral idiopathic optic perineuritis (OPN) presented with severe visual loss. A 64-year-old male with underlying hypertension, hypercholesterolemia, and schizophrenia presented with consecutively sudden onset of the right eye (RE) painless blurring of vision for two weeks and left eye (LE) painless blurring of vision for three days. The patient has no other symptoms such as red-eye, floaters, or headache. The patient had constitutional symptoms of loss of weight for the past three months; otherwise, he has no loss of appetite or persistent low-grade fever. Upon examination, RE visual acuity was no perception to light (NPL) at all quadrants, LE 6/36, and not improved with pinhole. The relative afferent pupillary defect (RAPD) was positive over the RE. Optic nerve functions of the RE were absent; meanwhile, over LE was reduced. The anterior segment was unremarkable, with no evidence of uveitis or dense cataract. Fundus examination showed diffuse 360-degree optic disk swelling with peripapillary splinter hemorrhage, mild tortuous vessel, and minimal vitreous hemorrhage inferiorly, with no evidence of neovascularization. The LE showed diffuse 360-degree optic disk swelling with normal macula and vessel. Magnetic resonance imaging (MRI) of the brain and orbit showed bilateral optic nerve sheath (ONS) enhancement with doughnut sign and tram-track sign. The patient was treated with bilateral OPN and started on intravenous methylprednisolone 1 g OD for five days followed by oral prednisolone 1 mg/kg OD with a tapering dose for one month. Patient visual acuity regained to RE 6/18 but did not improve with pinhole and LE 6/9 with full recovery of optic nerve function. Bilateral idiopathic OPN is a rare idiopathic inflammatory condition of ONS that typically presents with recurrent painless loss of vision with good recovery outcomes with intravenous steroids.