Journal List > J Korean Ophthalmol Soc > v.53(5) > 1009359

Chung, Park, and Park: Visual Function Test for Early Detection of Ethambutol-Induced Ocular Toxicity

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.

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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