Spheroidal degeneration of the cornea. Prevalence and association with other eye diseases.

A sample of 2,427 South African Negroes of the Pondo tribe was specifically examined for spheroidal degeneration of the cornea (S.D.C.). The prevalence of S.D.C. was 7.0% for the whole sample. It was twice as prevalent in men (9.9%) as in women (4.3%) and the prevalence increased with age over 50 for both sexes. The risk of having developed Stage II and III S.D.C. increased with age for men but not for women. The risk of having developed Stage III S.D.C. was not related to age or sex. No significant associations were found between S.D.C. and pterygium, cortical or nuclear cataract and glaucoma (all types and absolute glaucoma). There was a significant association between S.D.C. and pseudocapsular exfoliation for elderly men but elderly men with arcus senilis were less likely to have developed S.D.C. Poor corneal nutrition or metabolism are possible aetiological factors in the progression of S.D.C. to Stages II and III.