Racial differences of lens transparency properties with aging and prevalence of age-related cataract applying a WHO classification system

Purpose: To investigate racial differences of lens transparency properties and the prevalence of lens opacification by age.

Methods: Lenses of randomly selected Asian (1,038 Japanese and 517 Singaporeans) and Caucasian (1,045 Icelanders) subjects were evaluated for their lens transparency property (LTP). The prevalence of lens opacification was determined with a newly proposed WHO cataract classification system.

Results: LTP increased with aging for all nationalities. Light scattering intensity was significantly higher in the Singaporeans followed by the Icelandic subjects. The prevalence of cortical opacification in Singaporeans was significantly higher than those of the other nationalities up to the age of 60, and the prevalence in Asians was significantly higher than that in Caucasians aged 60-69. Cortical opacification was more prevalent than the other types for both Japanese and Icelanders in their 50s, 60s and 70s. Regarding the central optical zone, the prevalence in the Singaporeans was significantly higher than in the other two groups in their 50s and 60s. The prevalence of nuclear opacification in Singaporeans was markedly higher than those of the two other groups for all ages. Subcapsular cataract was the least prevalent type for all age groups and nationalities; however, the highest prevalence was observed in Singaporeans.

Conclusions: Lens transparency decreased with age in the Singaporeans more markedly than in the other two groups. The high prevalence of nuclear opacification in Singaporeans is considered to be due to environmental rather than race-specific factors.