Ocular ethambutol toxicity. A case report with electrophysiological considerations and a review of Danish cases 1972-81

A 76-year-old female with ocular ethambutol toxicity prompted two investigations. Firstly, she was followed electrophysiologically, with multichannel recorded pattern reversal visual evoked potential techniques using full-field, half-field, central-field and peripheral field stimulation, plus flash VEP and ERG. The examinations performed 2, 5 and 7 months after ethambutol withdrawal indicated damage to the papillomacular bundle, while a late follow-up after recovery showed potentials of near normal configuration. Secondly an epidemiological survey was attempted based on the 37 ethambutol toxicity cases registered to the Danish Board on Adverse Reactions 1972-81, making up 1% of those receiving antituberculous therapy. They showed a significant preponderance of elderly (24/37 greater than 65 years) and of females (29/37). There was only one foreigner in the series. A detailed analysis of visual function in a subsample of 22 cases (those registered 1977-81) showed that visual impairment lasted several months, and that usually recovery was not complete. Using the visual demands for driver's license as criterium, 20 fulfilled the demands prior to therapy, but only 12 after recovery.