Factors affecting visual outcome in patients with toxic optic neuropathy caused by ethambutol

This study aims to investigate prognostic factors for visual recovery in patients with ethambutol-induced toxic optic neuropathy (EON) by analyzing visual field (VF) tests, retinal nerve fiber layer (RNFL) thickness on optical coherence tomography (OCT), and other variables. We retrospectively reviewed 46 eyes of 23 patients with EON who had been followed up for more than six months. Patients were categorized into recovery (n = 12) and non-recovery (n = 11) groups based on visual recovery at six months after discontinuation of ethambutol. In the recovery group, initial best-corrected visual acuity (BCVA) and VF tests were better (p < 0.001), body weight (p = 0.04) was higher and the number of patient with diabetes (p = 0.007) was lower than in the non-recovery group. Baseline BCVA, VF tests, inferior and nasal RNFL thickness were correlated with visual outcomes. Univariate analysis showed that younger age (p = 0.024), higher body weight (p = 0.033), better initial BCVA (p < 0.001), better VF tests (p = 0.007), no hypertension (p = 0.044) and no diabetes (p = 0.009) were significant associated with a good visual outcomes. Multivariate analysis confirmed baseline BCVA as the only significant prognostic factor. Better BCVA at baseline are associated with favorable visual outcomes in EON patients. VF parameters, age, hypertension, diabetes, and body weight could also be considered possible predictors. Although RNFL thickness has significant correlation with visual outcomes, it does not appear to be a reliable factor to predict visual recovery.