Effect of Ethambutol on Visual acuity, Contrast Sensitivity and Color Vision in the Tuberculosis Patients Visiting Allied Hospital Faisalabad

Abstract

Introduction: Due to increase in prevalence of tuberculosis worldwide, first line anti-tuberculosis drugs are widely utilized. Ethambutol is one of the first line anti-tuberculosis drug. Ocular side effects are frequently reported due to it. Visual functions i.e. visual acuity, color vision; contrast sensitivity and visual fields get disturbed. Blue-yellow color vision defects are detected at first and are thought to be the first symptom of Ethambutol toxicity. Methodology: A descriptive cross sectional study was carried out at outdoor patient department of Tuberculosis, Allied Hospital Faisalabad to study the frequency of Visual acuity, contrast sensitivity and color vision defects in Tuberculosis patients due to ethambutol. Age limit of patients was 15-45 year. Sample of 120 subjects was taken by convenient sampling method. Proper informed consent was taken from all subjects under study. After taking appropriate history, clinical examination was performed. Log Mar chart for visual acuity, Pelli robsin for contrast sensitivity and Fransworth Munsell D-15 for color vision testing was used. Subject responses were recorded on proforma. Data was analyzed by utilizing SPSS programming software. Results: Descriptive statistics of Mean visual acuity recorded was 1.3 and standard deviation was ±0.46. Mean contrast sensitivity was 1.84 and standard deviation was ±0.44. Mean value of color vision was 1.60 and standard deviation was ±0.492. Overall, the results have found that 36 (30%) patients had impaired visual acuity while in 84 (70%) patients visual acuity was not impaired. 23 patients had normal contrast sensitivity (19.2%), 93 patients had moderate impairment (77.5%) and 4 patients had severe impairment of contrast sensitivity (3.3%). Color vision defects were recorded in 72 (60%) patients whereas 48(40%) patients had normal color vision. Out of 120 patients, 50 (41.7%) had no color vision defect, 19 (15.8%) of them had proton defect, 10 (8.3%) were of Deutan and 41 (34.2%) had Tritan defect. In Chi-square test statistic of Duration of Ethambutol and Visual acuity results are found significant at the level of 0.001. Results of duration of Ethambutol and Contrast sensitivity are significant at the level of 0.001. In relation of duration of Ethambutol and color vision the results are found significant at the level of 0.05. Conclusion: This study suggests that patients on Anti-tuberculosis therapy (ATT) must be monitored regularly and the drug should be stopped immediately when any visual function defect is detected.