Optic neuritis (ON) is a frequent manifestation in aquaporin-4 antibody (AQP4-IgG) seropositive neuromyelitis optica spectrum disorders (NMOSD). Due to limited samples, existing optical coherence tomography (OCT) studies are inconsistent regarding retinal changes in eyes with a history of ON (NMO-ON) and without a history of ON (NMO-NON), and their functional relevance.
The CROCTINO (Collaborative Retrospective Study on retinal OCT in Neuromyelitis Optica) project aims to reveal correlates of retinal pathology and to generate hypotheses for prospective OCT studies in NMOSD. The objective of this study was to analyze retinal changes of AQP4-IgG seropositive NMO-ON and NMO-NON eyes in an international cross-sectional OCT dataset.
Of 656 subjects, we enrolled 283 AQP4-IgG seropositive NMOSD patients and 72 healthy controls (HC) from 22 international expert centers. OCT data was acquired with Spectralis SD-OCT, Cirrus HD-OCT and Topcon 3D OCT-1. Mean thickness for the combined ganglion cell and inner plexiform layer (GCIP) and inner nuclear layer (INL) were calculated from macular volume scans. Clinical, functional and laboratory testing were performed at discretion of each center.
We compared NMO-ON eyes (N = 260), NMO-NON eyes (N = 241) and HC eyes (N = 136). GCIP was reduced in NMO-ON (57.4 ± 12.2 µm) compared with NMO-NON (75.9 ± 7.7 µm; p < 0.001) and HC (81.4 ± 5.7 µm; p < 0.001). NMO-NON had thinner GCIP (p < 0.001) compared with HC. INL was thicker in NMO-ON (40.3 ± 3.9 µm) compared with NMO-NON (38.6 ± 3.9µm; p < 0.001), but not HC (39.4 ± 2.6 µm). Microcystic macular edema were visible in 6.6 % of NMOSD eyes.
AQP4-IgG seropositive NMOSD is characterized by a functionally relevant loss of retinal neuroaxonal content and a - probably inflammatory - increase of INL after ON. Our study further supports the existence of attack-independent damage in the visual system of patients with AQP4-IgG seropositive NMOSD.