Evaluation of the retinal nerve fiber layer in neuromyelitis optica spectrum disorders: A systematic review and meta-analysis

Background. An increasing number of studies have investigated the value of optical coherence tomography in patients with neuromyelitis optica (NMO) spectrum disorders; however, no systematic review has been performed to date. We aimed to systematically review and investigate the possibility of differentiating NMO and multiple sclerosis (MS) via an optical coherence tomography measurement. Methods: Electronic databases, including MEDLINE, EMBASE and Web of Science, were systematically searched up to June 2017. A meta-analysis was performed to compare the retinal nerve fiber layer (RNFL) thickness between patients with NMO and MS (or healthy controls). Results: Twenty-four studies were identified. The meta-analysis demonstrated that the RNFL loss was substantially more severe in NMO than in MS; however, subclinical axon damage was also found in eyes without optic neuritis in NMO. The intereye RNFL difference between eyes with or without optic neuritis was more prominent in NMO (- 30.98 mu m) than in MS (- 9.87 mu m). Conclusion: The RNFL loss was more severe in NMO than in MS, and the intereye RNFL difference between eyes with or without optic neuritis may be useful in differentiating NMO from MS.