The incidence of keratoconus among ethnic groups is not accurate as keratoconus as a disease is often underdiagnosed particularly among patients with less access to medical and eye care. Studies have place the incidence of keratoconus anywhere from 1 in 500 to 1 in 30,000 depending upon the source. One long-term study put the incidence as 2 new cases per 100,000 per year.
Keratoconus occurs in virtually every ethnic group and some studies have concluded that the chance of keratoconus does not vary among different ethnic groups. The CLEK study (Collaborative Longitudinal Evaluation of Keratoconus) was a five year study that provided base-line information about keratoconus. Patients were being treated for keratoconus at centers from around the country. In this study, demographics were not specifically selected but ethnicity was reported as part of the study. By race, 68% were Caucasian, 19.9% were African-American, 8.2% were Hispanic, and 3.4% were a mix of other ethnic categories. As this does not vary remarkably from the demographics of Americans in general, this study does not provide any strong evidence that keratoconus is linked to any specific ethnic group.
One study conducted in Britain concluded that keratoconus was more common among Asians, specifically northern Pakistanis, than among patients of Caucasian origin. The author of the paper attributes this to interfamilial relationships, especially first-cousin marriages.
Since keratoconus does show links to genetics and heredity it is certainly likely that certain ethnic groups would be more predisposed towards keratoconus. Strong links between ethnicity and keratoconus have not been shown in the literature available and many researchers have concluded that keratoconus is not related to ethnic status.
In our own practice, there is some evidence that Hispanics have a higher incidence of keratoconus. This connection is not documented elsewhere however. As keratoconus is studied further we can continue to analyze correlation between keratoconus and ethnic groups.
