As a testimony to how prevalent uncorrected refractive error is in the developing world, refractive error in Nigerian adults and the prevalence of spectacle use was studied. In an article titled Refractive errors in Nigerian adults: prevalence, types and spectacle coverage, researchers looked at types of refractive errors and the ability of off the shelf spectacles to meet the corrective need in the 13,599 Nigerian adults. Patients underwent autorefraction and a detailed clinical exam and it was discovered that uncorrected refractive errors were responsible for 77.9% of visual impairment at the 20/40 to 20/60 level, and 57.1% at the 20/60 to 20/200 level. It also found that spectacles could improve the vision of 1,279 adults in the 20/40 range and 882 participants at the 20/60 level. However, only 3-4% of those individuals wore spectacles.