Does ethnic origin influence the incidence or severity of keratoconus?

Keratoconus affects all races, yet very little information exists as to the relative frequency in patients of different ethnic origin. We aimed to establish the incidence and severity of keratoconus in Asian and white patients.

The hospital records of the ophthalmology department of a large Midlands hospital with a catchment population of approximately 900,000 (87% white, 11% Asian, 2% other) were examined retrospectively for the 10 year period from 1989 to 1998.

For the age group 10-44 years the prevalence of keratoconus in Asians and whites was 229 and 57 per 100,000 respectively, a relative prevalence of 4 to 1. The incidence of keratoconus in the same age group was 19.6 and 4.5 per 100,000 per year respectively, a relative incidence of 4.4 to 1. Asians were significantly younger at presentation compared with whites (mean 22.3 +/- 6.5 vs 26.5 +/- 8.5 years, p < 0.0001). A first corneal graft was carried out on 14% of the Asian and 15% of the white patients. Of those having grafts, Asians were significantly younger than white patients at the time of diagnosis (mean 19.1 +/- 4.8 vs 25.7 +/- 7.3 years, p = 0.005) and at operation (mean 21.4 +/- 5.0 vs 28.7 +/- 7.7 years, p = 0.004). The interval from diagnosis to operation, though shorter for Asians, was not significantly different (mean 1.8 +/- 1.4 vs 2.5 +/- 1.7 years, p = 0.2).

The results show previously unrecognised racial differences in the hospital presentation of keratoconus in the UK. Compared with white patients, Asians have a fourfold increase in incidence, are younger at presentation and require corneal grafting at an earlier age.