New genetic test flags people with up to 10 times the usual risk of glaucoma, the leading cause of permanent blindness

A new genetic test can pick out people who are up to 10 times more likely than others to get glaucoma, an eye disease that slowly destroys sight and usually causes no symptoms until damage is done, according to a study published this week in the journal Ophthalmology.  Researchers at QIMR Berghofer Medical Research Institute, a medical research center in Brisbane, Australia, and Flinders University led the work.

Glaucoma damages the optic nerve, the cable that carries signals from the eye to the brain.  About half of people who have it don’t know it, and lost vision cannot be restored, the institute said.  Treatment works best when the disease is caught early.

What it could mean for you

The test is a “polygenic risk score,” a single number that adds up the small effects of millions of tiny DNA differences a person inherits.  The researchers say it could help eye doctors decide who needs closer checkups and earlier treatment, and who can be checked less often.

In Australians of European ancestry, people in the top 10% of genetic risk were 10 times more likely to have glaucoma than everyone else.  They also got the disease about 25 years earlier, on average, than people in the bottom 10%.  A healthy 65-year-old in the top 20% has about a 10% chance of getting glaucoma in the next 10 years, compared with 0.4% for someone in the bottom 20%, the study found.

Seonix Bio, a company co-founded by the lead researchers, sells a saliva test called SightScore in the U.S.  An eye-care professional must order it, results take four to six weeks, and Medicare, Medicaid and private insurance do not cover it, according to the company’s website.  The site does not say whether the U.S. test already uses the new score.

You do not need a DNA test to protect your eyes.  The National Eye Institute, part of the National Institutes of Health, says people are at higher risk if they are over 60 (especially Hispanic or Latino people), Black and over 40, or have a family member with glaucoma.  It says people at higher risk should get a comprehensive dilated eye exam, in which drops widen the pupil so the doctor can see the optic nerve, every one to two years.

How the study worked, and its limits

The team built the score from genetic data on more than 6 million people, including almost 300,000 with glaucoma.  The earlier version, from 2020, used about 8,000 glaucoma cases and found about a fourfold jump in risk.  “To our knowledge, this is the strongest genetic risk prediction reported for any common complex disease,” said Stuart MacGregor, the lead researcher, in the institute’s announcement.

The score also predicted who would get worse.  Among people with early or suspected glaucoma, 24% of those at highest genetic risk needed glaucoma surgery by age 80, compared with none at lowest risk.

The test found higher-risk groups in people of European, African, East Asian, South Asian and Hispanic ancestry, but it worked best in people of European ancestry, because most large genetic databases come from them.  The researchers say more study is needed to show whether using the test for screening is worth the cost.  Several authors, including MacGregor, hold financial interests in Seonix Bio, two work for the consumer DNA company 23andMe, and the institute holds a licensing interest, the institute disclosed.

Source:  QIMR Berghofer announcement; *Ophthalmology* study00788-8/fulltext); National Eye Institute glaucoma page; Seonix Bio U.S. patient page.