“…22 This contrasts with surveys in India, 6,23,24 Australia, 25 Taiwan, 26 Finland, 27 China, 28 and Myanmar where NO predominated. 29 More population-based data on the morphological types of opacities are required from Africa to explore reasons for the differences between regions. One explanation for the predominance of CO in our study is that Nigeria lies near the equator, with high sunlight intensity particularly in northern areas, as ultraviolet light is an important risk factor for CO. 8 Another reason may be because cigarette smoking, a risk factor for NO, is uncommon in Africa, including Nigeria.…”