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Presentation type	E-poster
Title	Reversibility of Visual Loss in Ethambutol-Induced Optic Neuropathy

Purpose	To evaluate reversibility of visual loss and evolution of visual field defects and peripapillary retinal nerve fiber layer (RNFL) thickness in a group of patients diagnosed with ethambutol-induced optic neuropathy.
Methods	Retrospective study.
Results	We included 8 patients. Based on patterns of visual field loss (preferentially temporal) and subsequent macular ganglion cell layer loss (preferentially nasal hemiretina), six patients were suspected to have chiasmal disease. Despite discontinuation of treatment, the visual field defects found at presentation were progressive in all of the patients in this group with best-corrected visual acuity (BCVA) also initially degrading in four of them. The two remaining patients were not found to present with, or evolve towards, a chiasmal syndrome. In those patients, neither visual field defects nor BCVA degraded from baseline, nor were they as important: baseline BCVA 0.42 LogMAR vs 0.57 LogMAR (1.23 LogMAR at nadir) and baseline visual field mean deviation(MD) -4.3 dB vs -7.68 dB (-16.0 dB at nadir). Reversibility was found in all patients, but final visual function was better (BCVA 0.006 LogMAR vs 0.16 LogMAR and MD -1.95 dB vs -5,97 dB) and visual recovery was faster (per patient first improvement in BCVA after 18 days vs 69 days and final BCVA after 88 days vs 282 days) in patients with non-chiasmal disease. RNFL measures appeared slightly thickened at presentation and tended to temporarily increase even after discontinuation of treatment.
Conclusion	Reversibility of visual loss was found in all patients, but was faster and better in patients without chiasmal disease. With the exception of one patient, visual recovery was compatible with the needs of normal (comfortable) daily functioning.
Conflict of interest	No

Authors 1

Last name	BUELENS
Initials	T
Department	CHU Saint-Pierre
City	Brussels

Authors 2

Last name	Willermain
Initials	F
Department	CHU Saint-Pierre
City	Brussels