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.