Eye infections due to contact lenses are in part genetically determined, research reveals.

The discovery explains why some contact lens wearers do everything wrong and never have a problem, while other more careful people end up in hospital with an eye infection.

“We used to think it was only a matter of luck,” says Dr Nicole Carnt, an optometrist and Scientia Fellow at the School of Optometry and Vision Science, UNSW.

“However, my research has shown that some people are more susceptible to getting an infection because of their genes. Some people’s genes even mean they could get a more serious infection than others.”

Nicole ran a retrospective study of inflammation of the cornea – looking at two conditions, known as infective and sterile keratitis – recruiting participants from studies that took place in Australia and London from 2003 to 2005. 

DNA was collected via cheek swabs, and sent in by post.

Different versions of four genes involved in inflammation were linked with an increased susceptibility to, and severity of, keratitis.

“Identifying genetic markers for susceptibility to keratitis will help with the design of a genetic tool to indicate how suitable contact lenses are for each person, and their infection risk profile,” Nicole says.

“So in the future, when you go to the optometrists to decide if you would like to try contact lenses, you might be asked to open your mouth for a DNA swab to calculate your risk of infection.

“And if you get an infection from contact lenses, when you go to hospital, your DNA might help the doctors work out the best management plan for your condition. Applying a personalised strategy like this could help save sight, and lead to healthier contact lens wear.”