People with asthma, sleep apnea or Down syndrome are at higher risk of developing an eye condition that causes serious progressive nearsightedness at a relatively young age, a new study has found.
The findings, made through the largest-ever clinical study of the condition called keratoconus, could help more people receive new treatments that can protect their vision.
Keratoconus makes the cornea weak, which leads it to become cone-shaped over time.
The study from University of Michigan in US showed that men, African-Americans and Latinos, and people with asthma, sleep apnea or Down syndrome, have much higher odds of developing keratoconus.
However females, Asian-Americans and people with diabetes appear to have a lower risk, the analysis shows.
“Eye health relates to total body health, and we as ophthalmologists need to be aware of more than just eyeballs when we see patients,” said first author Maria Woodward, assistant professor at the UM Medical School.
The researchers looked at data from health insurance claims - half of them from more than 16,000 people with confirmed keratoconus and half from an equal number of people with similar characteristics but no keratoconus.
This helped see which medical conditions were most associated with keratoconus, and which were not. The people in the study were mostly in their 30s and 40s.
The study helps confirm many suspicions about the condition raised by previous small studies ï¿½ but casts doubt on others, researchers said. For instance, men were already known to have a higher risk, which the study confirmed.
People with Down syndrome had a much higher chance of having keratoconus ï¿½ six times higher than others ï¿½ a known risk but still a stark one.
This reinforces the high importance of screening and treatment for the condition in members of the Down syndrome community, starting at a young age, Woodward said.
However, the higher rates of keratoconus among people of African American and Latino origin ï¿½ 50 per cent higher than whites - were previously unknown.
Also, the finding of a 39 per cent lower rate among people of Asian heritage contradicts previous research.
Meanwhile, there has been debate over a possible “protective” effect of diabetes. While diabetes causes other negative effects to the eye, the cornea may be strengthened as a by-product of those changes.
The new finding of 20 per cent lower odds of keratoconus among people with diabetes, and an even lower odds among those with complications from diabetes, appear to support this idea.
However, in people who had sleep apnea ï¿½ which interrupts breathing during sleep, and can cause snoring, daytime sleepiness and a higher risk of heart disease and stroke ï¿½ there was a statistically significant higher odds of also having keratoconus.
Similarly, people with asthma had higher odds of also having the eye condition.
The findings were published in the journal Ophthalmology.