Purpose: To evaluate the prevalence of aquaporin 4 antibody (AQP4-Ab) in new-onset optic neuritis patients and investigate the characteristics of seropositive patients.
Methods: Thirty-six women and six men with new-onset isolated optic neuritis were included in this study between January 2013 and December 2014. AQP4-Ab was detected and all blood samples were obtained prior to treatment and within one week from attack. The patients were sub-grouped into either a seropositive group or a seronegative group according to AQP4-Ab. Differences in age, gender, initial visual acuity, and final visual acuity between groups were analyzed.
Results: Six (14.3%) of these patients (five women and one man) exhibited AQP4-Ab. There was no significant difference in mean age between study groups (positive group: 38.7 ± 11.5 years, negative group: 42.3 ± 14.7 years, P=0.548). Bilateral simultaneous involvement was more common in seropositive patients than in seronegative patients (occurred in two out of six seropositive patients and in one out of 36 seronegative patients, P = 0.007). With regards to poor visual outcome (worse than 1.0 LogMAR), seropositive patients exhibited more severe visual loss than seronegative patients. None of the seropositive patients exhibited myelitis symptoms during the follow-up period (mean follow-up period: 8-32 months).
Conclusion: The prevalence of AQP4 antibody was often detected in new-onset optic neuritis patients. In patients with bilateral involvement or poor initial visual acuity, the AQP4 antibody test should be considered.
Keywords: Aquaporin 4-antibody; Korean; neuromyelitis optica; optic neuritis; prevalence.