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Updated: Aug 9, 2026

Multifocal Electroretinograms
Published on: December 4, 2011
Multifocal ERG in ethambutol associated visual loss
R S Behbehani1, E L Affel, R C Sergott
1Neuro-ophthalmology Service, Wills Eye Hospital, 840 Walnut Street, Philadelphia, PA 19107, USA. r_behbehani@hotmail.com
Aim:
To determine the anatomical site and extent of electrophysiological dysfunction in patients with ethambutol associated visual loss.
Methods:
A comparative case series. Four patients with ethambutol associated visual loss underwent multifocal electroretinography (mERG). Two patients had advanced visual loss while two had early signs of toxicity. The N1-P1, N1, P1 amplitudes, N1, and P1 latencies were compared to 10 age and sex matched controls.
Results:
mERG abnormalities were detected in the ethambutol treated patients. The N1 amplitude was significantly lower in the ethambutol treated patients than in the control group.
Conclusion:
Ethambutol is possibly toxic to the retina, and not only the optic nerve. The multifocal ERG may be of value to diagnose and monitor patients taking ethambutol.
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