The Use of Optical Coherence Tomography in Patients With Ethambutol-induced Optic Neuropathy

ABSTRACT

PURPOSE: To evaluate the efficacy of optical coherence tomography (OCT) on diagnosis and follow-up in patients with ethambutol-induced optic neuropathy and to evaluate the prognosis of ethambutol-induced optic neuropathy. METHODS: Seven patients (14 eyes) with a history of ethambutol-induced optic neuropathy underwent best corrected visual acuity measurement (BCVA), visual field exam, fundus exam, and OCT at their first visit and again six months later. RESULTS: There was an overall statistically significant improvement in vision (p=0.001); however, two patients (four eyes) showed no improvement. A decrease in RNFL thickness was observed in all eyes. Additionally, there was a statistically significant decrease of 6.4 +/- 5.37 micrometer (6.8%) in the mean RNFL thickness (p=0.003), with the greatest decrease in the temporal quadrant, which showed a mean decrease of 6.1 +/- 5.31 micrometer (9.2%) (p<0.001). CONCLUSIONS: Optical coherence tomography may be not only a valuable tool in the quantitative and structural analysis of RNFL thickness in patients with ethambutol-induced optic neuropathy, but may also provide objective information on diagnosis and follow-up. Toxicity from ethambutol is reversible with discontinuation of the drug, and vision recovers gradually. However, impaired vision can remain even with cessation of ethambutol due to retinal nerve fiber damage.