Risk factors for ethambutol optic toxicity.
BACKGROUND
Optic neuropathy is a well-known complication of ethambutol therapy and usually manifests as a decrease in visual acuity, cecocentral scotomas, and deficits in color vision.


OBJECTIVE
To support or disprove the hypothesis that a significant majority of patients who develop ocular toxicity while undergoing treatment for a mycobacterium infection do so after experiencing either a prolonged course or unusually high serum levels of ethambutol.


METHODS
Retrospective chart review (16 cases) and literature meta-analysis (54 cases).


RESULTS
Many cases lacked important data, but none countered the hypothesis. Age, duration of ethambutol, and dose of ethambutol were positively correlated with risk of toxicity.


CONCLUSIONS
Given an understanding of the risk factors for ethambutol optic toxicity, there exists a rationale for an optimization of ethambutol dosing protocols that can maximize the therapeutic effect while minimizing the incidence of optic toxicity.
Talbert Estlin
Katherine Anne
KA
Doheny Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA. kestlin@gmail.com
Sadun
Alfredo A
AA
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000995:Antitubercular Agents / Q000008:administration & dosage / Q000009:adverse effects* / Q000097:blood; D003117:Color Vision Defects / Q000139:chemically induced / Q000453:epidemiology; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004977:Ethambutol / Q000008:administration & dosage / Q000009:adverse effects* / Q000097:blood; D005260:Female; D006801:Humans; D007668:Kidney / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009161:Mycobacterium; D012189:Retrospective Studies; D012307:Risk Factors; D012607:Scotoma / Q000139:chemically induced / Q000453:epidemiology; D014397:Tuberculosis, Pulmonary / Q000097:blood / Q000188:drug therapy / Q000382:microbiology; D014786:Vision Disorders / Q000139:chemically induced* / Q000453:epidemiology; D015354:Vision, Low / Q000139:chemically induced / Q000453:epidemiology
D000995:Antitubercular Agents; D004977:Ethambutol