Ocular Morbidity Among Methadone users in Kathmandu Valley

INTRODUCTION: Methadone is used as an oral substitution therapy to intravenous drug users to minimize the side effects of the intravenous drug use. This study is conducted to find out ocular morbidity among methadone users in Kathmandu valley. METHOD: Clients on methadone maintenance therapy at a rehabilitation centre Kathmandu were included in the study.A cross sectional study was conducted with a sample size of 68 in the year 2013.Ocular examination included visual acuity testing, extraocular movements, cover test, colour vision, stereoacuity, horizontal prism fusion range, accommodation and schirmer’s test. Anterior segment and posterior segment were evaluated. RESULT: Among 68 participants, 17.6% were hepatitis C positive, 10.3% were HIV positive and 5.9% had history of pulmonary tuberculosis. Age ranged from 20 to 59 years with 66.17% in the age group 21-30 years. 91.17% participants were males. Regarding the duration of methadone use, 48.52% were on methadone for less than 1 year, 8.82% for 1 year, 16.17% for 2 years, 10.29% for 3 years 4.41% for 4 years, 8.82% for 5 years and 4.41% for more than 5 years.20.58% were on 40mg of methadone. Regarding color vision, red green color defect was seen in 35.29%. Dry eye was seen in 51.47%. Regarding accommodation, 52.2% had 11-20 cm and 10.3% had >21 cm of accommodation while 37.3% had normal accommodation (6-10 cm). Horizontal fusion range was 10-20 prism dioptres in 39.70%, 21-30 prism dioptres in 14.70% and 31-40 prism dioptres in 44.11% while it was absent in 2.94% with manifest strabismus. Regarding the threshold of stereoacuity, 88.23% had ≤ 60 seconds of arc and 11.76% had >60 seconds of arc of stereoacuity. However, convergence has been found to be within normal limits among 78% methadone users. Refractive error was present in 47.05%, 1.4% had episcleritis, 1.4% had conjunctivitis and 1.4% had dragged disc. Statistically significant association has been observed between the dose of methadone and accommodation. CONCLUSION: Ocular morbidities like colour vision defect, dry eye, poor accommodation, reduced stereoacuity and poor horizontal fusion range was found among methadone users in Kathmandu valley.