November 7, 2005

Genetic, environmental factors may play roles in keratoconus

The incidence and severity of keratoconus were found to be high in a study of patients in a mountainous region of Saudi Arabia, with early onset and more rapid progression to severe disease stage at young age. The study authors suggest that genetic and/or environmental factors may play roles in the etiology of the disease.

Abdullah M. Assiri and colleagues studied 125 patients in the Asir province of Saudi Arabia with newly diagnosed keratoconus. The mean age of the patients was 18.5 years, and the study included 51 men and 74 women. All patients had been referred to the Asir Central Hospital.

The incidence of keratoconus in the region is 20 cases per 100,000 people, the authors said. Disease severity in the study population was high, they noted, as indicated by an early mean age (17.7 years) of patients with advanced stage keratoconus. Visual acuity with correction was 6/12 or better in 98% of the eyes measured.

The incidence of keratoconus in this study is comparable to that of 20 to 25 per 100,000 people of Asian descent living in the United Kingdom, but higher than the incidence of 1 in 100,000 in the white population in that country, the study authors noted.

More than half the patients (56%) in this study had atopic ocular disease; 16% had a positive family history of the disease and 16% had atopic dermatitis.

The Asir Province in Saudi Arabia is a mountainous region, and 95% of the study participants live at an average altitude of 3,000 meters, suggesting the environment may play a factor in disease development, the authors said.

“An early onset and increased severity of keratoconus … may be related to a combination of genetic and/or environmental factors,” the authors said. “Clinically, contact lens correction should be considered earlier to maximize visual performance.”

The study is published in the November issue of the British Journal of Ophthalmology.

Hari