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Chung, Park, and Park: Visual Function Test for Early Detection of Ethambutol-Induced Ocular Toxicity
Original Article
Journal of the Korean Ophthalmological Society

Journal of the Korean Ophthalmological Society 2012; 53(5): 694-699.

Published online: 16 May 2012

DOI: https://doi.org/10.3341/jkos.2012.53.5.694

Visual Function Test for Early Detection of Ethambutol-Induced Ocular Toxicity

Jae Keun Chung, MD1, Yong Beom Park, MD2, Sung Pyo Park, MD, PhD1

1Department of Ophthalmology, Hallym University Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.

2Department of Pulmonary and Critical Care Medicine, Hallym University Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.

Address reprint requests to Sung Pyo Park, MD, PhD. Department of Ophthalmology, Hallym University Kangdong Sacred Heart Hospital, #150 Seongan-ro, Gangdong-gu, Seoul 134-701, Korea. Tel: 82-2-2224-2274, Fax: 82-2-470-2088, sungpyo@hananet.net

Received 12 April 2011       Accepted 7 April 2012

Copyright © 2012 The Korean Ophthalmological Society

Abstract

Purpose

The purpose of the present study was to investigate various visual function tests for early detection of ethambutol-induced ocular toxicity.

Methods

A prospective study of 20 eyes of 10 patients being treated with ethambutol was conducted. Visual acuity, visual field, color vision, fundus examination, contrast sensitivity, optical coherence tomography (OCT), and pattern-visual evoked potential (VEP) were assessed. Examinations were performed prior to therapy and every month for 5 months after treatment. VEP was performed every other month. The mean values of each parameter at each month were compared with the baseline examination and a p-value of <0.05 was considered significant. In addition, a greater than 2 standard deviation (SD) change in each parameter from the mean values at baseline was considered as an ocular toxicity induced change in each individual eye.

Results

On OCT, a significant increase of the average retinal nerve fiber layer thickness was detected after 4 months of therapy. VEP showed an increased mean latency of the P100 wave after 2 and 4 months of therapy. However, a greater than 2 SD change from the mean values of the baseline was not observed on OCT, while 30% (6/20) of the eyes showed more than a 2 SD increase in VEP latency. Visual acuity, color vision, fundus, contrast sensitivity, and visual field were not affected in any patients.

Conclusions

The authors of the present study consider VEP as a sensitive test to detect early toxicity of ethambutol. VEP can be helpful in identifying subclinical ocular toxicity, especially in the high-risk patients.

Keywords: Early detection, Ethambutol, Ocular toxicity, Visual evoked potential

Figures and Tables

Table 1
Retinal nerve fiber layer thickness on optical coherence tomography (n = 20)
jkos-53-694-i001

SD = standard deviation.

*Comparison between baseline (before taking ethambutol) and each month (after taking ethambutol) (paired t-test); †p < 0.05.

Table 2
Pattern-visual evoked potential latency (n = 20)
jkos-53-694-i002

SD = standard deviation.

*Comparison between baseline (before taking ethambutol) and each month (after taking ethambutol) (paired t-test); †p < 0.05.

Table 3
Changes of visual evoked potential latency in each individual eye
jkos-53-694-i003

Pt = patient; OD = right eye; OS = left eye.

*2 month after taking ethambutol - Baseline (before taking ethambutol); †4 month after taking ethambutol - Baseline (before taking ethambutol); ‡>2 standard deviation (SD) change from the mean of VEP latency at baseline.

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