Epidemiological data on keratoconus highlight roles of ethnicity, environmental factors

PARIS — Epidemiological studies on keratoconus show that ethnicity and environmental factors are likely to play a major role in the etiology of the disease. However, “still very little is known about this mysterious condition,” according to Florence Malet, MD.

In her speech at the meeting of the French Society of Ophthalmology, she noted that keratoconus prevalence varies greatly according to geographical areas.

Florence Malet

“Ethnicity appears to have a major role. This is confirmed by a study carried out in the U.K., where prevalence was four times greater amongst citizens of Asian origin as compared to Caucasians,” Malet said.

In Iran, a highly significant difference was found between individuals of Persian and non-Persian origin, with a prevalence of 2.5% and 7.9%, respectively, based on topography data. In Lebanon, a high prevalence of 3.3% was found using keratometry. Also based on keratometry, a prevalence of 2.3% was found in rural India.

“Today we have objective means of investigation and more accurate results. However, the use of different technologies and classification criteria should be taken into account when comparing data,” Malet said.

Environmental factors could explain the lower prevalence of keratoconus in cold northern countries, such as Finland, Denmark and Russia, as compared with hot southern areas with great exposure to sunlight, such as India and the Middle East.

“The oxidative stress induced by UV light has been indicated as a possible risk factor,” Malet said.

Keratoconus has a complex etiology in which many factors are likely to concur, including genetic factors, allergies and eye rubbing, she said. - by Michela Cimberle

Disclosure: Malet reports no relevant financial disclosures.