Ocular toxicity of ethambutol.
OBJECTIVE
To review the literature on ocular toxicity of ethambutol--its background, clinical presentation, toxicity characteristics, management, monitoring, and preventive measures.


METHODS
Literature search of Medline from 1962 to May 2005.


METHODS
All related literature in English using the search formula: (ethambutol OR myambutol) AND (eye* OR ophthal* OR ocular) AND (adverse OR toxic).


METHODS
All information was collected and analysed by authors.


RESULTS
Ethambutol hydrochloride is a commonly used first-line anti-tuberculous agent. Although rare, ocular toxicity in the form of optic neuritis (most commonly retrobulbar neuritis) has been well documented since its first use in the 1960s. Classically described as dose- and duration-related and reversible on therapy discontinuation, reversibility of optic neuritis remains controversial. International guidelines on prevention and early detection of ethambutol-induced ocular toxicity have been published. Nonetheless, opinion of the clinical effectiveness of regular vision tests to enable early detection of toxicity is divided.


CONCLUSIONS
The course of ethambutol-induced ocular toxicity is unpredictable. Measures to ensure a high level of awareness in medical staff and patients of this potential adverse effect appear to be the best current preventive method. Classified by the World Health Organization as a place with an intermediate tuberculosis burden and good health infrastructure, Hong Kong is in a good position to examine the unanswered questions about ethambutol-induced ocular toxicity.
Department of Ophthalmology, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong.
R Y C
RY
Chan
A K H
AK
Kwok
D000995:Antitubercular Agents / Q000008:administration & dosage / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D004977:Ethambutol / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D009902:Optic Neuritis / Q000139:chemically induced* / Q000175:diagnosis / Q000517:prevention & control; D017410:Practice Guidelines as Topic; D020127:Recovery of Function; D013997:Time Factors
D000995:Antitubercular Agents; D004977:Ethambutol