Influence of ethnic origin on the incidence of keratoconus and associated atopic disease in Asians and white patients

Abstract

Purpose To investigate the influence of ethnic origin on the incidence of keratoconus and the association of atopic diseases in patients with keratoconus. Methods Retrospective study of new patients referred to Dewsbury District General Hospital and diagnosed with keratoconus in a 6-year period between 1994 and 2000. The ethnic origin of the patient was defined as white, Asian, or other. Incidence was calculated from the catchment population of 176 774 (82% white people, 17% Asians, 1% others). t-Test, confidence intervals and v 2 tests were used to show statistical significance. Results A total of 74 cases of keratoconus were diagnosed over this period. Of these patients 29 (39%) were white and 45 (61%) were Asian. This equated to an incidence of keratoconus of 25 per 100 000 (1 in 4000) per year for Asians, compared with 3.3 per 100 000 (1 in 30 000) per year for white people (Po0.001). Asians presented significantly younger than white patients. The incidence of atopic disease was found to be significantly higher in white compared to Asian keratoconic patients. Conclusions Asians were significantly more likely to present with keratoconus. The Asian patients were mostly of Northern Pakistani origin. This community has a tradition of consanguineous, especially first-cousin marriages. The higher incidence in this population was highly suggestive of a genetic factor being significant in the aetiology. The incidence was higher than revealed by previous studies. Atopic disease was significantly less common in Asians compared to white people, supporting the theory of a different aetiology in these patients.

The Dundee University Scottish Keratoconus study: demographics, corneal signs, associated diseases, and eye rubbing

“…Ethnic differences in the prevalence of keratoconus have been well documented. 6,21 Keratoconus is usually a bilateral condition, 23 although asymmetrical, 24,25 with the second eye lagging about 5 years behind the first. 26 In DUSKS, 88.5% were found to exhibit bilateral keratoconus, usually asymmetrical in presentation (P ¼ 0.005).…”

“…6 The aims of the DUSKS project were to investigate and correlate the corneal, refractive, topographic, and familial characteristics of people with keratoconus, within the Tayside region of Scotland.…”

The Epidemiology and Etiology of Keratoconus

“…The preponderance of men over women has been noted in the most recent studies. 20,[30][31][32][33][34][35][36] Georgiou et al 37 reported a difference of 2.6 times higher in men than women. Some, mainly older studies, have not found differences in the prevalence between genders.…”

Keratoconus: an inflammatory disorder?

“…Asians (people from India, Pakistan, and Bangladesh) have prevalence 4.4-7.5 higher than Caucasians. 39,40 Others authors have suggested that differences in exposition to ultraviolet light, according to latitude in the terrestrial globe could explain differences in prevalence according to geographical localization. 41 …”

“…On the other hand, consanguinity have been associated with a higher risk of development of keratoconus. 39,49 Recently, Kriszt et al 50 performed a segregation analysis of 60 unrelated sporadic keratoconus families and suggested that this type of keratoconus is a complex non-Mendelian disease. However, genetics does not seem to be the only factor in keratoconus, and as many researchers have suggested it is very probable that the vast majority of cases are the result of patients exhibiting genetic predisposition triggered by environmental factors.…”