Bilateral idiopathic optic neuritis in pregnancy

A 33-year-old primiparous woman at 31 weeks gestation with no prior history of ocular disease, autoimmune disease, or recent viral infection presented with rapidly decreasing visual acuity to 20/400 OD and counting fingers OS over 11 days. MRI demonstrated mild bilateral optic nerve enhancement. Humphrey 30-2 visual field testing showed bilateral seco-central scotomas. MR venogram, visual evoked potentials, preeclampsia workup, and serum blood tests for folate, B6, B12, Toxoplasmosis, Bartonella, Lyme disease, ACE levels, RPR, and LFTs were all within normal limits. After one-time treatment of IV 125 mg methylprednisolone and spinal tap, visual acuity improved to 20/20 OD and 20/20 OS.