Objective To observe the effect of intravenous methylprednisolone (IVMP) pulse therapy on the best corrected visual acuity (BCVA) and the number of relapses in patients with neuromyelitis optica spectrum disorder-related optic neuritis (NMOSD-ON) after total IVMP dose. MethodsA retrospective clinical study. From March 2020 to February 2023, 23 patients of 27 eyes with NMOSD-ON in Shanxi Eye Hospital were included in the study. BCVA examinations were performed on all affected eyes using the international standard visual acuity chart, which was statistically converted into logMAR visual acuity. Serum aquaporin-4 antibody (AQP4-IgG) was detected by indirect immunofluorescence assay based on cell detection technology in all patients. According to Guideline for the diagnosis and treatment of NMOSD spectrum disorders in China (2021 edition), patients were given IVMP impact therapy. Among them, 18 and 5 patients received 1 000 and 500 mg/d IVMP pulse therapy respectively for 3-5 consecutive days, followed by a reduction to 500 or 250 mg/d for 2-3 consecutive days. The average total IVMP dose during the treatment was 4 500 mg (1 500-5 250 mg). The changes in BCVA at 1 week, 1 month, 3 months, and 6 months after treatment were observed for the initial and post-treatment BCVA of ≤0.1, ＞0.1-<0.5, and ≥0.5. The changes of BCVA at 1 week and 1, 3 and 6 months after treatment were observed. The comparison of BCVA between different age, disease duration, and IVMP total dose conditions was performed using the Mann-Whitney U test. The comparison of BCVA between different relapse times was performed using the Kruskal-Wallis test. The influence of IVMP total dose on the number of relapses during the 6-month follow-up was analyzed using χ2 test. The factors affecting BCVA ≥0.5 after 6 months of IVMP treatment were analyzed by logistic regression, and the correlation between ΔlogMAR BCVA and IVMP pulse total dose was analyzed by Spearman correlation. ResultsIn 23 cases with 27 eyes, there were 3 males and 20 females. The median age was 35 years. The median duration of illness was 5 days. There were 21 (91.30%, 21/23) positive and 2 (8.70%, 2/23) negative cases of AQP4-IgG, respectively. There were 3 cases (13.04%, 3/23) with the first course of disease and 4 eyes (14.81%, 4/27). There were 20 cases (86.96%, 20/23) with recurrence course and 23 eyes (85.19%, 23/27). The median time from initial onset to the initiation of corticosteroid treatment was 7 days. During the 6-month follow-up after treatment, 5 patients (21.74%, 5/23) relapsed in 6 eyes (22.22%, 6/27), all of which were patients with initial relapse course. Among them, recurred 1 or ≥2 times in 4 (66.67%, 4/6) and 2 (33.33%, 2/6) eyes respectively. BCVA≤0.1, ＞0.1-＜0.5, ≥0.5 in 20, 4, 3 eyes and 3, 13, 11 eyes at the beginning and 6 months after treatment, respectively. There was significant difference in the number of eyes with BCVA≤0.1, ＞0.1-＜0.5 and ≥0.5 at different time after treatment (χ2=40.772, P＜0.001). The treatment effect of female patients was better than that of male patients. The patients with initial BCVA≥0.1 had more increased eye number of BCVA than those with BCVA＜0.1, the patients with first course of disease had more increased eye number of BCVA than those with recurrent course of disease, and the patients with total dose of IVMP ＞4 500 mg had less increased eye number of BCVA than those with total dose ≤4 500 mg. The differences were statistically significant (Z=−2.449, −2.904, −2.485, −2.286; P=0.014, 0.004, 0.013, 0.022). Logistic regression analysis showed that the higher the initial BCVA≤0.1 and the total impact dose of IVMP, the lower the possibility of obtaining BCVA≥0.5 after treatment (odds ratio=0.069, 0.899; 95% confidence interval 0.010-0.463, 0.798-0.998; P=0.006, 0.020). Spearman correlation analysis showed that ΔlogMAR BCVA was negatively correlated with total impact dose of IVMP (rs=−0.472, P=0.013). There was no significant difference in the number of recurrence after different total doses of IVMP (P＞0.05). ConclusionsIVMP total dose ≤4 500 mg can achieve better BCVA prognosis compared with IVMP total dose ＞4 500 mg. IVMP total dose has no effect on the number of recurrences after treatment.