Optic neuritis,
inflammation of the optic nerve, can cause
visual impairment through
retinal nerve fiber layer (RNFL) degeneration. Optical coherence tomography could serve as a sensitive noninvasive tool for measuring RNFL thickness and evaluating the
neuroprotective effects of treatment. We conducted a meta-analysis to compare RNFL loss between novel add-on treatments and
corticosteroid therapy at least 3 months after acute
optic neuritis. The outcome measures were mean differences (MDs) in (1) RNFL thickness compared with the baseline in the affected and unaffected eye and (2) LogMAR visual acuity (VA). Seven studies involving five novel agents (
memantine,
erythropoietin,
interferon-beta,
phenytoin, and
clemastine) were analyzed. When compared with the baseline RNFL thickness of the affected eye, the
neuroprotective effects of novel add-on treatments could not be demonstrated. The difference in visual outcomes was also not significant between the two treatment groups. One study revealed that
phenytoin has the potential to alleviate RNFL loss when the baseline thickness of the unaffected eye is considered. Larger randomized controlled trials with suitable outcome measures are warranted to evaluate the
neuroprotective effects of novel treatments. Further studies should also tailor
therapies to specific patient populations and investigate a more targeted treatment for acute
optic neuritis.