High prevalence of nuclear cataract in the population of tropical and subtropical areas.

The authors have conducted cataract epidemiological studies in four climatically and racially different places and compared the data. The survey places were Noto and Amami in Japan, Reykjavik in Iceland, and Singapore. The evaluation and grading of lens opacities were done using graphic analysis of Scheimpflug and retro-illumination images. The prevalence of nuclear opacity was extremely high in the Singapore group, followed by Amami. The main type of lens opacity was nuclear in the Singapore group and cortical in the Noto and Icelandic groups. The characteristic lens opacity in Amami was in between the above two groups. No significant difference was seen in the prevalence of nuclear opacity between males and females in any of the groups. Although the common factors of the living conditions in the subjects with a high prevalence of nuclear opacity appear to be high UV exposure and high ambient temperature, future investigations should be made to disclose the possible cause.