Prevalence, causes and magnitude of functional low vision in Sri Lanka: results from a national population based survey

Introduction The following definition of functional low vision is used in surveys to estimate the need for low vision services: corrected visual acuity in the better eye of less than 6/18 down to and including light perception from causes not amenable to treatment. However, such data for Sri Lanka is lacking. Objectives To determine the prevalence, causes and magnitude of functional low vision in a nationally representative sample of adults aged 40 years and above in Sri Lanka. Methods Distance visual acuity was measured using a LogMAR E chart. If the acuity was less than 3/60 in either eye, the ability to see hand movements, count fingers or perceive light was assessed. All underwent autorefraction followed by subjective refraction and measurement of best corrected acuity if indicated. Participants with a presenting acuity of