Objective: To determine if vitamin supplementation can prevent the development of color vision abnormalities in patients taking ethambutol as part of DOTS for tuberculosis (TB). Methods: A randomized, placebo-controlled, single-blind clinical trial was conducted among newly diagnosed category-1 TB patients enrolled in DOTS health centers in the third district of Manila from June 2011 to August 2012. Before starting therapy, the participants underwent a complete eye evaluation including baseline color vision tests using the Ishihara Color Vision Plates (Ishihara), Farnsworth Panel D-15 (FD 15), and Lanthony Desaturated D-15. Only subjects who passed the three color vision tests were included in the study. They were divided into 2 groups: Group A received vitamin supplementation and Group B received a placebo. Follow-up color vision testing was done monthly for 3 months. Results: There were 105 patients included in the study, 77 males and 28 females, age ranging from 16 to 68 years with a mean of 37 years. Forty three (43) patients received vitamin supplementation (group A) and 62 received placebo (group B). After one month of DOTS, 5 of 43 patients (11. 6%) in group A and 10 of 62 patients (16.1%) in group B developed color vision abnormalities, detected only with the Lanthony Desaturated test. The absolute risk reduction (ARR) of color vision abnormalities by vitamin supplementation was 4.5%, with the number needed to treat (NNT) of 23. After the second month of therapy, ARR was 7.4% and NNT was 14. ARR was highest in the third month at 8.3%, with a corresponding decreased NNT of 12. Among patients who developed color vision abnormalities, reversal of the abnormalities was observed in 80% of 5 subjects in group A, and 40% of 10 patients in group B. By the third month of treatment, all in group A already had normal color vision, while 40% in group B still showed abnormal color vision. Conclusion This study showed that vitamin supplementation was effective in reducing the risk of, and in reversing cases of, color vision abnormalities among patients undergoing DOTS therapy for tuberculosis.
Tuberculosis ; Ethambutol ; Color Vision ; Optic Neuritis