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 <6/12 in the better eye were examined in details and a cause of visual loss was assigned. Analysis included those who fulfilled the definition of functional low vision. Results Among those examined, 59 participants fulfilled the definition of functional low vision: prevalence 1.02% (95% confidence interval 0.77-1.31%). The commonest causes were complications of cataract surgery (42.4%), and posterior segment conditions (30.5%) principally and age related macular degeneration (5 cases) and other retinal conditions (11 cases). Based on these estimates, 77,600 adults in Sri Lanka may benefit from low vision services. Conclusions The prevalence of functional low vision is slightly lower than the prevalence of blindness from all causes. Complications of cataract surgery are potentially avoidable causes

Prevalence and types of refractive errors, and spectacle coverage in Sri Lankan adults: The Sri Lanka National survey of blindness and visual impairment

Introduction Uncorrected refractive errors are the commonest cause of visual impairment globally. Despite this, the proportion of affected individuals who wear spectacles can be low, particularly in low and middle- income countries. No data were available for Sri Lanka. Objectives To estimate the prevalence of refractive errors and investigate their risk factors among adults aged 40 years and above. Another purpose was to calculate spectacle coverage and identify subgroups with low coverage. Methods Cluster random sampling was used to obtain a nationally representative sample. Presenting distance visual acuity was measured using a logMAR chart, with distance spectacle correction if usually worn. All underwent autorefraction and an optician measured best-corrected visual acuity after subjective refraction. Participants who had undergone cataract surgery were excluded. Spectacle coverage was assessed amongst participants with a visual acuity of <6/12 in the better eye due to refractive error who attended the examination site with spectacles. Results 5,779/6,713 (86.1%) enumerated adults were examined; 5,179 had refraction data. 67% had a refractive error: hyperopia 49.6%; myopia 17.4%. Refractive errors increased with age. Being aged 60 years and above and Sinhala ethnic group were independent risk factors. Spectacle coverage was 17.7% overall, being lower in females and the non-literate. Based on the findings, 1.66 million adults require spectacles for distance correction. Conclusions Refractive errors are very common in Sri Lankan adults, and there is a large unmet need for spectacles. Affordable services for refractive errors need to be scaled up, focusing on the most underserved subgroups in the population