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Genetic testing puts ODs on the front line of AMD management
Optometrists can help ease the growing burden of treatment with this early intervention.
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Prior to its application in eye care, genetic testing gained traction in many medical specialties. It aids in the fight against breast cancer as researchers have discovered genetic indicators that give oncologists a tremendous advantage in predicting a patient’s likelihood of developing the disease. It has guided the diagnosis and treatment of autism spectrum disorder in children with an identifiable genetic cause.
Now, for patients with early age-related macular degeneration (AMD) or a family history of AMD, genetic testing can assess their risk of converting to choroidal neovascularization (CNV) or developing advanced AMD. This allows eye care professionals to better manage those patients and, most importantly, potentially prevent vision loss.
Ongoing research
Seddon and colleagues have determined that genetic testing can predict the risk of patients with AMD developing CNV with an accuracy of up to 96%. The eyeGene project, sponsored by the National Eye Institute, has been researching blood samples in patients with diseases such as retinitis pigmentosa, Stargardt’s disease and choroideremia for 5 years, according to the NIH Record. These are diseases that we normally would not have much power to treat, but they have strong genetic indicators and are passed down through generations.
Leo P. Semes
With better characterizations of genetic patterns and the development of genetic engineering, there is promising evidence of corrective action in animal models. In the case of AMD, if we can determine which patients are at greater risk of converting to CNV, we can alter patient management to yield better outcomes.
Benefits of genetic testing
The utilization of genetic testing for AMD has several advantages, the least of which is that we can determine which of our patients are most at risk for developing a degenerative disease. With this information, we can alter our protocols in regard to how often we see patients and how closely we monitor them.
A patient with high-risk genetic indicators can be examined every 2 to 6 months, depending on his or her specific level of risk. In fact, patients at the greatest risk of progressing to CNV should be seen five times more often than patients who are at low risk, according to Hannum and Perlee. When we adjust our monitoring schedule based on risk, we can potentially catch conversions to CNV earlier and refer the patient for treatment on a more urgent timetable. Early intervention with therapies such as anti-VEGF injections can be key in managing the progression of AMD.
We can also advise a patient with more conviction when it comes to taking vitamins and adopting healthy lifestyle habits, such as refraining from smoking and incorporating UV and, especially, short wavelength visible light protection.
Steven Ferrucci
Practitioners who adopt genetic screening for AMD may find that their practices benefit as well. When a patient has been determined to be at a higher risk, he or she should be examined more frequently. OCT and fundus autofluorescence can be used to monitor progression in an attempt to catch a conversion to CNV more quickly and thus reduce lines of vision loss prior to treatment.
In addition to more vigilant observation on the ECP’s part, the patient can feel confident knowing that everything possible is being done to manage their disease and prevent vision loss. Early intervention is an important consideration with any potentially progressive disease. In many cases, when the community at large begins to discover that a practice specializes in AMD and genetic testing, patients will seek out the practice as a leader in the field.
Candidate genes that can be identified as “risk alleles” are being perused. One option for genetic testing is MaculaRisk PGx (ArcticDx). AutoGenomics also has a test in development.
Incorporating genetic testing
Many eye care professionals do not know how to incorporate genetic testing into their practice or understand how the concept of testing can influence practice protocol and patient management. However, interest in the concept is growing, and education is available.
A retina specialist can observe tissue abnormalities and create a treatment plan for a patient that involves making the macula thinner or restoring the integrity of the vascular system, but this approach treats the condition after it has reached a critical point. This creates an opportunity for optometrists, as we are at the front line of preventive care. As such, we have the opportunity and responsibility to test patients while they are in the early stages of AMD, or even prior to the onset of disease, and prevent progression or development of advanced AMD.
Public health concern
As noted in the Age-Related Eye Disease Study, AMD is increasingly understood as a considerable burden on health care resources if untreated in the early stages. If a patient converts to CNV, the burden becomes even larger, and the costs compound. Optometrists are the primary eye care providers, and with sufficient testing capabilities we can ease this burden with simple observation and early intervention.
Genetic testing is in its infancy, and while much of the technology available to us today for AMD is new, it is a promising advance in eye care that will continue to gain ground.