# Long-term Indian optic neuritis study (THE LION STUDY): clinical, imaging features and visual behavior of optic neuritis in Indian population over two decades

## TL;DR

This study examines optic neuritis in India over two decades, finding more optic disc swelling and similar visual outcomes compared to other Asian studies.

## Contribution

The study provides a long-term analysis of optic neuritis in an Indian population, highlighting differences in disease patterns compared to Western cohorts.

## Key findings

- Females were more commonly affected, with unilateral involvement in 70% of cases.
- Optic disc edema was present in 50% of patients at presentation.
- Idiopathic optic neuritis and NMOSD-ON were more common than MS-ON in this cohort.

## Abstract

The study aims to understand the disease course of optic neuritis in the Indian population and analyze their demographic patterns, clinical features, and treatment responses over a period of two decades.

We retrospectively reviewed the medical records of patients with optic neuritis (ON) who presented to the neuro-ophthalmology clinic of a tertiary eye center between 1997 and 2017. Clinical profiles, neuroimaging features, and post-treatment visual outcomes were analyzed.

A total of 406 eyes from 314 patients were included in this study. The mean age at presentation was 36.28 ± 12.58 years. Females were more commonly affected (N = 191patients, 60%). Unilateral involvement was noted in 70% (222 patients), and pain was associated with 63% (200 patients). The mean vision at presentation was 20/500 ± 20/158 (log MAR 1.39 ± 0.898). Optic disc edema was noted on presentation in 50% of patients (204 eyes). The mean vision post-treatment was 20/44 ± 20/91 (log MAR 0.34 ± 0.66). Recurrent optic neuritis was observed in 26.75% of patients (84 patients). Neuromyelitis optica antibody (NMO Ab) was positive in 19 patients, and myelin oligodendrocyte glycoprotein antibody (MOG Ab) was positive in one patient. Optic neuritis was of idiopathic etiology in 88.8% of patients, multiple sclerosis (MS) in 5.8%, and 4.8% had conversion to MS by 3years.

This ON study group of the Indian population had more optic disc edema on presentation and visual outcomes similar to those of other Asian studies, unlike ONTT. Idiopathic ON and neuromyelitis optica spectrum disorder-optic neuritis (NMOSD-ON) were more common than MS optic neuritis (MS-ON) in this cohort population. Prospective long-term follow-up of these patients can reveal the natural disease course, neurological associations, and treatment outcomes.