A case of anti-aquaporin-4 antibody-positive optic neuritis treated by selective immunoadsorption.

Anti-aquaporin-4 (AQP4) antibody-positive optic neuritis is a condition in which a patient testing positive for anti-AQP4 antibody presents with optic neuritis only. The disease is classified as a neuromyelitis optica spectrum disorder (NMOSD) and is a steroid-resistant refractory optic neuritis. Patients are treated by oral administration of steroids, steroid pulse therapy, and apheresis therapy. The patient in our case was a 48-year-old female who was diagnosed with anti-AQP4 antibody-positive optic neuritis by her ophthalmologist, and was referred to our hospital. Selective plasma exchange (SePE) was initially started, but she strongly preferred treatment as an outpatient due to family circumstances. Therefore, selective immunoadsorption (SeIA) was used from the second session to minimize loss of coagulation factors. The RRs were 16.5-33.3% for anti-AQP4 antibody, 7.48-18.57% for fibrinogen, and 0.8-4.57% for factor XIII. After the 7th SeIA session, the patient was followed up with a maintenance dose of 10 mg/day oral prednisolone as an outpatient at our Department of Ophthalmology. This is the first report to investigate the removal rate (RR) of anti-AQ4 antibody using SeIA. In our case, the anti-AQP4 antibody level before the last SeIA session was still not completely negative, but there was clinical improvement in vision. SeIA was highly effective in maintaining coagulation factor levels. Therefore, our results suggest that SeIA is a safe treatment that can be performed in an outpatient setting.