エタンブトール視神経症の検討

Review of ethambutol-induced optic neuropathy

要約　目的：エタンブトール（以下，EB）視神経症の発症頻度およびその経過についての検討。対象と方法：最低3か月以上経過観察できたEB内服患者405名（男性218名，女性187名平均58.4歳）を対象とした後ろ向き研究。全例で視力および中心フリッカ値（以下，CFF値）を測定し，一部の症例で色覚および視野について検討した。結果：EB視神経症発症者は405例中7例で発症頻度1.73％であった。男性3例，女性4例で，平均年齢は72.4歳（61～81歳）であった。いずれもEB中止となり徐々に視力とCFF値は改善したが，2例3眼では高度の視力障害が残存した。これらは，投与中止までに時間がかかった症例であった。結論：EBは時に重篤な視神経障害を生じることがあるので，早期に発見し投薬中止の検討をすることが重要である。

Abstract.　Purpose：To present a review of optic neuropathy among patients treated by peroral ethambutol. Cases and Method：This study was made on 405 patients who received ethambutol in the past 126 months. The series comprised 218 males and 187 females. The age ranged from 19 to 89 years, average 58 years. In addition to ethambutol, patients with tuberculosis received rifampicin and isoniazid. Patients with atypical acid-fastbacterial infection received clarithromycin. Cases were checked for visual acuity and critical flicker fusion frequency（CFF）every 2 months at least. Results：Optic neuropathy developed in 7 out of 405 cases（1.73％）. They included 3 males and 4 females. Optic neuropathy developed later than 6 months of treatment with ethambutol except in one case. The total dosis of ethambutol before onset of optic neuropathy ranged from 29 to 180g, average 121g. Visual acuity and CFF gradually improved after discontinuation of ethambutol except in 3 eyes of 2 cases. No case showed full recovery of visual acuity to the pretreatment level. Conclusion：Patients receiving peroral ethambutol may develop optic neuropathy and need close ophthalmological follow-up.