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

Kim, Bu Ki; Ahn, Min

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.