Clinico-epidemiologic characteristics of optic neuritis in a tertiary eye centre in Eastern India based on the status of serum aquaporin-4 antibody

Purpose: To elucidate the clinico?epidemiologic characteristics of optic neuritis based on the status of serum aquaporin?4 antibody (AQP4?Ab) in patients with optic neuritis (ON). Methods: Medical records of 106 patients with ON and a follow?up of 3 years were reviewed. For each patient, the following data were extracted: medical history, findings of the ocular examination, brain, orbital or spinal MRI, and serological tests for AQP4. The ON was classified as typical or atypical based on disc examination and improvement in vision after intravenous methylprednisolone (IVMP). The clinical findings (typical or atypical), disease course, and outcomes were analyzed according to the serostatus of the ON. Results: 10 patients ((9.4%) were seropositive for AQP4?Ab; all had atypical ON. 96 patients (91%) were seronegative for AQP4?Ab: 36 atypical ON and 60 typical ON. Profound visual impairment at presentation was seen in all patients. However, at the end of the study period, seropositive and seronegative atypical ON had poor visual outcomes as compared to seronegative typical ON (P = 0.002). Five seropositive and four seronegative patients with atypical ON developed transverse myelitis. Bilateral disease with relapse was more in seropositive patients (80%); however, seronegative with atypical ON also had bilateral presentation and relapse in 42% and 41%, respectively. Conclusion: AQP4?Ab seropositive patients mostly present with atypical features such as bilateral recurrent ON, poor visual outcome, and increased incidence of transverse myelitis. However, atypical clinical features can also be seen in seronegative ON with a poor visual outcome and a recalcitrant course.