1) During the past 6 years from Dec.1962 to Dec.1968, 421 cases of pulmonary tuberculosis patients were treated with ethambutol for 1 to 48 months (the average 11.9 months). During this period, 15 cases (3.57%) of visual impairment were experienced.
2) Except 11 cases originally treated, the majority of cases were resistant to SM and INH, and almost all cases were already treated with KM, TH, and CS. Dividing by the extent of pulmonary lesions according to NTA classification, 44% were far advanced, 47% were moderately advanced, and 44% of the cases were over 10 years since the onset of the disease.
3) As shown in Table 1, visual impairment occured rather suddenly from 54 day s to 23months after starting EB treatment. Consequently, there is no definite time for its onset, but all the cases except one case complained visual impairment before the periodic routine vision tests. This suggests that the frequent routine vision examination is not always necessary.
4) Visual impairment is the most remarkable symptom and many showed r apid, marked fall of the vision (Fig.1). Including 1 case which showed visual impairment 20 days after the cessation of EB, we experienced 7 cases which showed continuous downfall of the vision even after stopping EB. The visual impairment recovered within 2 months in 3 cases, but it required approximately 6 months in the other cases.
5) Visual field test showed the e nlargement of the blind spot and the relative central scotom in most of the cases. Out of 9 cases examined, 8 cases showed abnormal visual field (Fig.2).
6) 11 cases showed color blindness but all were temporarily.
7) Fundus examination showed pictures of acute r etrobulbar neuritis in half of the cases. The remaining 7 cases showed neuritis and retinitis and among them, 3 cases showed retinal hemorrhage (Fig.3). The fundus examination conducted on 147 cases treated by EB without any side-affects showed clearly that the above hemorrhage was characteristic (Table 2).
8) No correlation was seen between the visual impairment and sex, body weight (Table 4), dose/kg of EB (Table 5), extent of the disease (Table 6), the period from the onset of the disease (Table 7), and diabetes (Table 9). The incidence of visual impairment was higher in the older age groups (Table 3).
9) No significant differen c e was found in the incidence of the side-affects between EB 0.5g per day group and 1.0 g per day group, and between EB 1.0 g once a day group and twice daily group (Table 8).
10) Vitamin B
1 was u s ed in all the cases as treatment for the side-affects, and in 6 cases vitamin B
12 treatment was added. The effectiveness of these vitamins for visual impairment was not clear, and we presume that the recovery of visual impairment was quite probable only by stopping EB at a right time.
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