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Glaucoma affects an estimated 300,000 Australians but half of them don’t know it. Early detection is considered vital to prevent irreversible vision loss and blindness.
With the global eyecare sector’s focus on World Glaucoma Week between 6–12 March, Insight takes a closer look at advances in glaucoma research in Australia, particularly innovations in testing and diagnostic technologies.
Recognising the limitations of current glaucoma screening techniques, including timeliness and cost effectiveness, researchers have seized on the opportunity to target these shortcomings to design low-cost tests that deliver rapid results.
Not only can their new screening and diagnostic tools detect glaucoma sooner, they could potentially one day form part of national screening programs and alleviate the direct and indirect costs of glaucoma to the Australian healthcare system, projected to hit $784 million by 2025.
This month Insight speaks with three researchers, all non-eye care professionals but experts in their chosen fields, about their work to develop all new imaging devices – and even a blood test – to pick up high-risk individuals before irreversible vision loss sets in.
Genetic testing for degenerative eye disease
Dr Georgie Hollitt from Flinders University College of Medicine and Public Health, and Flinders Medical Centre, is leading a prospective assessment of polygenic risk scores to predict diagnosis of glaucoma and age-related macular degeneration.
Known as the Genetic Risk Assessment of Degenerative Eye Disease (GRADE) study, Hollitt is building on the work from previous work including a long-running international collaboration between Flinders University and the QIMR Berghofer Medical Research Institute, and other research partners around the world, to identify genetic risk factors for glaucoma.
Working alongside Professor Jamie Craig and Associate Professor Owen Siggs, both from Flinders University, Hollitt is part of a team of Australian researchers who have identified 107 genes that increase the risk of glaucoma, and developed a genetic test using thousands of common genetic variants to detect people at risk of going blind from the condition. Their ultimate aim is to be able to offer blood or saliva tests to people when they turn 50 (regardless of family history) so they can find out if they are at risk, and then act to prevent vision loss.
“Glaucoma and age-related macular degeneration (AMD) are the two most common causes of irreversible vision loss among elderly people worldwide. This is because both diseases are asymptomatic in the early stages, there are no clear screening recommendations for either condition, and broad community screening is not currently cost-effective,” Hollitt says.
“This is problematic as current glaucoma treatment options are highly effective at slowing or preventing disease progression, while AMD treatments for early-stage disease are currently undergoing clinical trials. For these reasons, identifying cost-effective screening methods to facilitate early diagnosis and timely intervention is important. This can be achieved with polygenic risk score (PRS) testing.”
Flinders University is conducting a prospective clinical trial which aims to clinically validate the PRS tests for both glaucoma and AMD.
The study is inviting 1,000 individuals aged over 50 years from the general population in South Australia to have their PRS calculated for both conditions.
“The scores will be used to categorise participants as being in either the highest 10%, lowest 10% or within the middle 80% of risk within the study population, based on our previous work in Nature Genetics,” Hollitt says.
The previous study she is referring to characterised optic nerve photographs of 67,040 UK Biobank participants and used a multi-trait genetic model to identify risk loci for glaucoma.
“A portion of individuals from each group will then undergo a thorough eye examination to compare the rate of glaucoma or AMD diagnostic classification across the risk spectrum of the PRS, with an expectation to see a higher rate of glaucoma and AMD diagnosis in the high-risk groups of the PRS compared to the average or low risk groups,” Hollitt says.
“The tests, performed on a blood or saliva sample, have the potential to identify high-risk individuals before irreversible vision loss occurs, and also have the potential to allow glaucoma and AMD screening to reach a broad population. With more data supporting the clinical validity of this testing, PRS may soon become part of routine clinical care.”
Hollitt says the application of PRS testing would not be possible without assessing the attitudes of healthcare professionals towards it.
To that end, Flinders University is also conducting a questionnaire-based study assessing this in the context of glaucoma.
“Healthcare professionals, including ophthalmologists, optometrists and orthoptists, will be at the forefront of the delivery of personalised medicine so it will be important to demonstrate acceptability of PRS testing from these groups before it is implemented into clinical practice,” Hollitt explains.
“This confidential online survey will inform training and resources for healthcare workers who may be involved in offering the test, referring or counselling patients as well as interpreting results from the test.”
(For more information regarding GRADE and the questionnaire, contact Dr Georgie Hollitt at georgie.hollitt@flinders.edu.au).
In addition to the GRADE study, the same team has expanded on the Targeting at Risk Relatives of Glaucoma patients for Early Diagnosis and Treatment (TARRGET) study after preliminary results were reported last year.
This family-based study, a partnership between Glaucoma Australia, Flinders University, the University of Western Australia/Lions Eye Institute, the University of Tasmania, Sydney Eye Hospital and WA Department of Health, provides personalised risk information to family members of a person with glaucoma and encourages them to have a glaucoma screening appointment.
The first phase of TARRGET approached immediate family members of people with advanced glaucoma and has recently expanded to include family members of people with non-advanced disease.
To date, more than 3,500 people with glaucoma have been sent forms requesting mailing information for their family. From this, more than 2,000 family members have been sent personalised risk information and 785 family members have completed an eye check and provided information back to the study regarding their glaucoma status.
Based on current return rates, the study expects to receive contact details for approximately another 2,000 family members who will, over the coming 12 months, also receive personalised information regarding their risk of developing glaucoma based on the type and severity of glaucoma in their affected family member.
Feedback from family members to date indicates that more than 50% of those contacted have glaucoma or show suspicious early signs of glaucoma requiring monitoring (glaucoma suspects). These are family members of people with advanced disease, and in the future the study will continue to include data from family members of those with non-advanced glaucoma. The study encourages family members to talk to each other about glaucoma and reminds participants that eye health checks must be a regular and ongoing commitment to prevent vision loss.
Related Articles
Part 1: The Future of Glaucoma Detection and Monitoring
Part 3: Computerised glaucoma screening test
Published with permission from www.insightnews.com.au
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