This study investigated the benefits of early treatment with high-dose intravenous methylprednisolone in patients with aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) antibody-positive optic neuritis.
Study design
The Optic Neuritis Treatment Trial (ONTT) established that treatment with IV methylprednisolone leads to faster recovery from optic neuritis, but does not change the patient’s ultimate outcome. However, this trial was conducted prior to knowledge of AQP4 and MOG antibodies, which are biomarkers of atypical optic neuritis. In the present study, the authors retrospectively explored variables that influenced visual outcomes in 18 patients with AQP4-IgG and 9 patients with MOG-IgG optic neuritis.
Outcomes
The study revealed significant correlations between 3-month vision outcomes with age (P=0.04) and number of days to methylprednisolone treatment (P=0.03). Further analysis revealed that patients treated with steroids later than 4 days after onset had a relatively lower chance of recovery to 20/20 (OR 8.3), and those treated later than 7 days after onset had a relatively lower chance of recovery to 20/30 or better (OR 10).
Limitations
While this study suggests that earlier treatment with methylprednisolone leads to better outcomes, the retrospective design could have potentially influenced the findings. Patients with poor spontaneous recovery may be more commonly referred to tertiary centers, which could create a biased link between delayed treatment and poor outcomes.
In addition, some patients with AQP4-IgG optic neuritis were treated with plasma exchange, which could potentially alter outcomes. Lastly, there was a relatively small number of patients with MOG-IgG optic neuritis; therefore, a larger study is needed to confirm this finding. This is important in light of a recent study of MOG-IgG in the ONTT, which revealed 3 patients with MOG-IgG optic neuritis who all recovered to 20/20 despite 2 being randomized to receive low-dose oral prednisone and 1 receiving placebo.
Clinical significance
This interesting study suggests that earlier treatment with steroids leads to better visual outcomes for patients with AQP4-IgG or MOG-IgG optic neuritis. This conclusion has important implications because AQP4-IgG and MOG-IgG test results often takes 1 to 2 weeks. Therefore, their findings suggest early IVMP should be considered for all cases of optic neuritis because antibody testing results would not be back before the optimal window of treatment has elapsed. However, the study’s retrospective nature and small sample size limit its generalizability. While this study suggests that “time equals vision,” larger prospective studies will be required to confirm this notion.