Recovery in NMOSD-Related Optic Neuritis Poor, Worsened by Treatment Delays

Findings from a 10-year, single-center study of Thai patients revealed that the significant risk factors of having poor visual outcomes were neuromyelitis optica spectrum disorder-related optic neuritis (NMOSD-ON), with an odds ratio (OR) of approximately 10 times, and a delay in the administration of intravenous methylprednisolone treatment.

The trial featured 76 individuals, 61 of which had optic neuritis, to investigate the clinical characteristics of subgroups of optic neuritis, and to evaluate the potential factors predicting good visual improvement. Patients with optic neuritis were categorized into 3 groups based on seropositive markers: double seronegative optic neuritis (DN-ON; n = 33), NMOSD-ON (n = 18), and multiple sclerosis-related optic neuritis (MS-ON; n = 10). DN-ON was classified as cases of double seronegative result of aquaporin-4 antibody and myelin oligodendrocyte glycoprotein antibody.

Led by senior investigator Thansit Srisombut, MD, Faculty of Medicine, Rajavithi Hospital, Thailand, visual outcome was determined by corrected visual acuity (VA) in logMAR between the initial and 12-month follow-up period. Significant improvements in visual outcomes were considered improvements of at least 0.3 logMAR. A female predominance was observed in all 3 groups, particularly in the NMOSD-ON group, but without any statistically significant difference among the groups (P = .076).

"The present study noted a female predominance, particularly in NMOSD and double seronegative optic neuritis, which is in line with the findings of other reports," the study authors wrote. "The impact of gender on visual outcome seems to vary substantially in the literature. Guo et al. proposed that females with NMOSD-ON attained a significantly better therapeutic response; however, some researchers have found contrary results, reporting that there was no association between gender and visual outcome among NMOSD, MS or double seronegative optic neuritis, which was in concordance with our conclusion that gender had no bearing on visual improvement in the three optic neuritis groups."

At the end of the 12-month period, the mean BCVA values in logMAR were 0.26 (±0.42), 1.23 (±0.78), and 0.36 (±0.5), for DN-ON, NMOSD-ON, and MS-ON, respectively. Significant differences in BCVA were observed between the NMOSD-ON and DN-ON groups, as well as the NMOSD-ON and MS-ON groups (both P <.001). Notably, no improvement of 0.3 logMAR was observed in NMOSD-ON eyes (0%), and this was significantly different among the 3 groups (P = .022). the 3 groups did not significantly differ in color vision improvement and recurrence rates (P = .204; P = .103, respectively).

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On univariable analyses, DN-ON increased the likelihood ratio of attaining an improvement of at least 0.3 logMAR with an OR of 0.16 (95% CI, 0.06-0.449; P <.001), and NMOSD-ON was a significant predictor of visual outcome (OR, 16.67; 95% CI, 4.763-58.314; P <.001). Furthermore, delay of more than 7 days in commencing treatment with intravenous methylprednisolone (IVMG) resulted in a higher OR of 2.65 (95% CI, 1.000-7.007; P = .05). Poor baseline VA at nadir also increased the risk of poor visual outcomes (OR, 16.19; 95% CI, 5.097-51.398; P <.001).

In terms of limitations, the authors noted, “First, because of its retrospective nature and inevitable missing data, the improvement in some visual parameters such as the change in optic nerve thickness measured by optical coherence tomography could not be evaluated as a treatment outcome. Second, our results may not be generalizable for MOG-related optic neuritis groups because our hospital is an adult referral center; therefore, our results may not be applicable in pediatric populations. In addition, our institute treats very few cases of MOG. However, our study reveals that NMOSD-ON carries a risk of poor visual improvement, and it identifies the benefits of rapid treatment of IVMP within 7 days in attaining good visual recovery in Thai patients."

REFERENCE
1. Kemchoknatee P, Singhakul C, Arjkongharn N, Chainakul M, Tangon D, Srisombut T. A 10-year single-center study of the clinical characteristics of optic-neuritis NMOSD, MS, and double seronegative optic neuritis, together with factors predicting visual outcomes. Vision. Published February 28, 2023. doi:10.3390/vision7010016