Real-world application of the updated criteria of optic neuritis
Fernando Falcão1, Sara Terrim1, Guilherme Silva1, Samira Apostolos Pereira1, Dagoberto Callegaro1
1Universidade de São Paulo
Objective:

Apply the new diagnosis and classification criteria for optic neuritis in a predominantly non-caucasian population in a resource-limited setting of an emergent country.

Background:

Optic neuritis presents a manifestation of different neurological and systemic disorders with distinct disease course. Objective diagnostic criteria are important for early recognition and should be applicable for distinct etiologies in different ethnic populations and geographical regions. New diagnostic criteria has been published by Petzold et al in 2022, based on clinical assessment and paraclinical tests establishing two different categories:  definite and possible optic neuritis; they also proposed an etiological classification for this condition. However, this new criteria have not yet been applied in a real-world population with great ethnic variability.

Design/Methods:
We propose a retrospective case series study of patients with confirmed optic neuritis based on the new proposed diagnostic criteria, admitted to our service between January 2015 and December 2020. We collected data of clinical aspects (laterality, pain, time of evolution, visual acuity, and relative afferent pupillary deficit), radiological investigation (orbit MRI, OCT was not available) and biomarkers (AQP4, MOG, oligoclonal bands in the CSF). We classified patients according to 2022 diagnostic criteria and etiological classification of optic neuritis. 
Results:

We analyzed 69 patients with confirmed optic neuritis. According to the new diagnostic criteria, 50 (72%) patients were classified as definite and 19 (28%) as possible optic neuritis. Based on the new etiological criteria, 30% patients had multiple sclerosis, 20% NMOSD (of this, 64% AQP4+), 4% MOGAD, 18% CRION, 20% SION and 5% infectious or systemic secondary neuritis. 

Conclusions:
Objective diagnostic criteria are important for early recognition of different possible etiologies of optic neuritis, which may have diversified clinical manifestations. Petzold et al criteria were applicable in an ethnic diverse population of a developing country with variable etiological classification. 
10.1212/WNL.0000000000204157