More than 15 times more effective than existing genetic tests in identifying individuals at high risk of glaucoma. It is the promise of a new genetic test whose characteristics have been analyzed in a study just published in Jama Ophthalmology and carried out thanks to an international collaboration between Flinders University, the QIMR Berghofer Medical Research Institute and other research partners around the world. who have been working for years to identify genetic risk factors for glaucoma, the leading cause of blindness worldwide. In Italy 800 thousand people suffer from it, of which 2.5% are over 40 years of age.
How is glaucoma diagnosed
Glaucoma is an asymptomatic disease: the patient does not realize that he is affected and complains of very vague symptoms such as vision of halos and collision with objects. Precisely for this reason it is difficult to make an early diagnosis. But how is a diagnosis currently made? “The clinical diagnosis of glaucoma – he explains Luciano Quaranta, former full professor of Diseases of the visual apparatus of the University of Pavia and member of the board of directors of the Lombard Ophthalmology Society – is based on goniosocopy to identify open-angle and angle-closure glaucoma and on tonometry, i.e. the measurement of pressure intraocular “. Other useful tests are ophthalmoscopy, that is the observation of the optic nerve head and perimetry, that is the evaluation of the functional damage of the spatial visual capacity. “These four semeiological investigations performed by the ophthalmologist – continues Quaranta – allow us to make an accurate diagnosis of glaucoma”. What about high-tech diagnostics such as the Oct and Oct of the iridocorneal angle? “It can be useful – replies the specialist – but not fundamental and only complementary for a correct diagnosis of the disease”.
A tool for screening
According to the lead author of the Jama study, Professor Jamie Craig from Flinders University, this new research highlights the potential the new genetic test may have for glaucoma screening and management. “Genetic testing is currently not part of the routine of diagnosing and treating glaucoma, but this test has the potential to change that. We now have the opportunity to start testing it in clinical trials,” says eye doctor Craig who also runs a international glaucoma research program at Flinders University, funded by the Australian National Health and Medical Research Council.
The results of the study
The latest results presented in the journal Jama evaluated the performance of genetic tests on 2507 Australian patients with glaucoma and 411,337 individuals with or without glaucoma in the UK. It is estimated that one in 30 Australians will eventually develop glaucoma, many of which are diagnosed late due to a lack of symptoms. The new test, performed on a blood or saliva sample, has the potential to identify high-risk individuals before irreversible vision loss occurs. Research team members are also launching a spin-out company to develop an accredited test for use in clinical trials, with patient recruitment expected to begin in 2022.
At what point is the research
Glaucoma is a disease in which multiple risk factors are involved. But beyond this study, where are the genetic tests for diagnosis? “There is no single specific biomarker for glaucoma and diagnosis involves evaluating the clinical characteristics of the disease,” explains Quaranta. “More than 100 genes related to a person’s increased risk of developing glaucoma have been identified. The evaluation of a polygenic risk score can allow the earlier detection of the disease and give a ‘score’ of the severity of the evolution of the disease itself. To date, however, except for congenital glaucoma (CYP1B1 gene), there are no genetic tests capable of making a diagnosis of the disease “.
The importance of early diagnosis
Once diagnosed, several treatment options can slow or stop the progression of glaucoma vision loss. “Early detection of this condition can lead to sight-saving treatment, and genetic information can potentially give us an advantage in making early diagnoses and making better treatment decisions,” he says. Owen Siggs, a specialist at Flinders University in South Australia and the Garvan Medical Research Institute in Sydney. Professor Quaranta also fully agrees: “Today we are able to make an increasingly early diagnosis of the disease and to manage it optimally through pharmacological, laser and surgical treatments. However, since glaucoma is a totally asymptomatic disease in the initial stages, it is extremely important that awareness campaigns are carried out to induce the population to perform an eye examination at least at the onset of presbyopia which generally occurs around 40/45 years of age. Unfortunately, the damage caused by glaucoma is irreversible and therefore the earlier the diagnosis is, the greater the chances of avoiding visual impairments ”.
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