The main emphasis in this study is on the three most common potentially blinding diseases in the age group 43 years and older, i.e. cataract, age related macular degeneration and open angle glaucoma. The prevalence of all three diseases increases with advancing age (P less than 0.001, corr. greater than 0.8). In the age group 63 years and older there is a statistically significant difference in the occurrence of cataracts between females and males (P less than 0.02). Females outnumber males and the former appear to develop cataract at an earlier age than men. Among persons 73 years of age and older there is a statistically significant difference in the occurrence of open angle glaucoma between males and females (P less than 0.05), whereby males outnumbered females. Persons with age related macular degeneration were divided into an exudative group and an atrophic group. There was no sex difference in the atrophic group, whereas females outnumber males by 2:1 in the exudative group, which is mainly accounted for by overrepresentation of females 83 years and older. Persons 83 years and older who had age related macular degeneration also had cataracts in all instances and open angle glaucoma in 23.8% of cases. Sixteen persons were legally blind i.e. had visual acuity less than or equal to 6/60 in the better eye or visual field less than 10 degrees in the better eye. Eight persons thereof, were greater than or equal to 83 years of age.