An article published this year surveyed people with keratoconus living in Saudi Arabia.  Optometrists invited their patients to complete a questionnaire that asked about their ethnicity, education, habits like eye rubbing, other medical conditions like dry eye or allergies, and other family members with the disease.

Because the study was based entirely on subjective reporting by patients, there may be some weaknesses with the study, but the authors made one undeniable observation.  There was a higher concentration of keratoconus among people living in higher altitudes.  Saudi Arabia is a country that contains mountain, desert, and coastal regions.  Despite a lower population density than the other regions, there was a much higher prevalence of keratoconus in the mountains.

These results are similar to the findings of a US-based study published last year.  Using Vision Service Plan (VSP) insurance claims database, the authors were able to gather information on plan members with KC including age, sex, and state of residence. In every category, Colorado led the nation in the number of individuals with keratoconus.  Other Western states like Utah, Wyoming, and Nevada also report high rates of disease.

Could there be a connection between ultraviolet radiation or lack of oxygen that exists at high elevation and KC?  Dr. Emily McCourt MD is Associate Professor of Ophthalmology at the University of Colorado.   She diagnoses and treats many children with KC and cautions there is more to learn before we accept that altitude plays a role in the development of KC.  “This raises an important research question that warrants more attention,” according to McCourt.  She noted, “Understanding environmental factors that possibly play a role in the development of keratoconus is extremely important. Studies like this these help us think more about why certain populations develop keratoconus, and this information could potentially help lead us to more customized treatments.”

What we learned:  Research studies suggest a link between keratoconus and certain environments

Reference:

Demographic and clinical variations of keratoconus in Saudi population.  Al Quhtani, Abahussin MO, Assiri A, Saudi J Ophthalmol 36:42-46, 2022.

Estimated Prevalence of Keratoconus in the United States from a Large Vision Insurance Database, Munir, SZ, Munir WM, Albrecht A, Eye & Contact Lens, 47:505-510, 2021.