July 15 (UPI) -- A new genetic test for glaucoma is 15 times more accurate at identifying people at high risk for the eye disease than existing diagnostics, a study published Thursday by JAMA Ophthalmology found.
The test, performed on a blood or saliva sample, is designed to spot multiple genetic mutations known to cause the disease before irreversible vision loss occurs, the researchers said.
"Genetic testing is not currently a routine part of glaucoma diagnosis and care, but this test has the potential to change that," study co-author Dr. Jamie Craig said in a press release.
"We're now in a strong position to start testing this in clinical trials," said Craig, a professor of ophthalmology at Flinders University in Adelaide, Australia.
Glaucoma, which is the leading cause of irreversible blindness and affects 3 million adults in the United States, is typically diagnosed using a variety of instruments to examine the eye, according to the Glaucoma Research Foundation.
Using these instruments, ophthalmologists check for a number of signs of the disease, including rises in inner eye pressure and changes in the shape and color of the optic nerve and the thickness of the cornea, among others.
However, these approaches often fail to spot glaucoma before vision loss occurs, making treatments designed to reduce inner eye pressure and slow or halt the progression of vision loss less effective, Craig and his colleagues said.
Historically, genetic testing for glaucoma risk has focused on the MYOC p.Gln368Ter variant, the most common single-gene variant known to cause glaucoma, according to the researchers.
Conversely, their approach is designed to identify multiple variants involved in the development of the disease to develop a polygenic risk score, which measures the total number of genetic changes related to the disease.
For this study, the researchers, based in Australia, evaluated the performance of their genetic test on 2,507 Australians with glaucoma and 411,337 people with or without the disease in Britain.
High polygenic risk was six times more common among study participants with glaucoma than the MYOC p.Gln368Ter variant, the data showed.
It was also 15 times more common than the variant in the general population, meaning it is a more effective way to spot the disease in those who do not yet have outward symptoms, the researchers said.
They are launching a company to develop an accredited test for use in clinical trials, with recruitment expected to begin in 2022, they said.
"Early diagnosis of glaucoma can lead to vision-saving treatment," study co-author Owen Siggs said in a press release.
"Genetic information can potentially give us an edge in making early diagnoses and better treatment decisions," said Siggs, an associate professor at the Garvan Institute of Medical Research in Sydney.