Microcystic Inner Nuclear Layer Abnormalities and Neuromyelitis Optica

Importance: Microcystic abnormalities involving the inner nuclear layer of the retina occurs in a subset of patients with multiple sclerosis, most commonly in eyes previously affected by symptomatic optic neuritis. Acute optic neuritis is a cardinal manifestation of neuromyelitis optica (NMO). To our knowledge, microcystic inner nuclear layer abnormalities have not been investigated in NMO. Objective: To establish whether microcystic inner nuclear layer abnormalities occur in NMO. Design: Observational, retrospective study. Setting: University of California at San Francisco Multiple Sclerosis Center (academic specialty clinic). Patients: Twenty-five consecutive patients with NMO based on 2006 diagnostic criteria or with NMO spectrum disease (defined by seropositivity for anti-aquaporin 4 IgG in the context of a single episode of transverse myelitis or optic neuritis). Exposure: Spectral-domain optical coherence tomography. Main Outcomes and Measures: Identification of microcystic inner nuclear layer pathology on spectral-domain optical coherence tomography. Multivariable linear regression was used to examine associations between microcystic changes and measures of retinal structure and function. The hypothesis was generated prior to the data being reviewed and analyzed. Results: Microcystic changes were identified in 5 of 25 patients with NMO (20%) and 7 of 48 total eyes, including 7 of 29 eyes (24%) previously affected by optic neuritis. Microcystic changes occurred exclusively in eyes with a history of acute symptomatic optic neuritis (100% of eyes with microcystic changes had experienced prior optic neuritis compared with 71% of NMO eyes without microcystic abnormalities). There were no significant differences between patients with NMO with and without microcystic changes in terms of age, sex, and aquaporin 4-IgG antibody status. The mean age in this cohort was 44 years (range, 13-81 years); 84% were women; 80% were aquaporin 4-IgG seropositive; and the median Expanded Disability Status Scale score was 4.0 (interquartile range, 3.0-6.5). Conclusions and Relevance: Microcystic inner nuclear layer pathology occurs in a proportion of patients with NMO in eyes previously affected by acute optic neuritis. Additional research is needed to understand the cause of this retinal pathology and determine whether it contributes to persistent visual disability in patients with NMO following optic neuritis.