In this MD Newsline exclusive interview with vitreoretinal specialist Dr. Murtaza Adam, we discuss risk factors for wet AMD.
Is there a genetic predisposition for wet AMD?
Dr. Murtaza Adam:
“Really, we don’t fully understand the genetic causes of age-related macular degeneration (AMD). We have implicated at least 70 genes in the development of wet AMD. That doesn’t include the many other genes associated with dry AMD. Those genes interact with other genes and the environment.
So I think we do know that there is some genetic influence on the incidence of AMD. So, for example, that’s why we see differences in wet AMD development across racial/ethnic groups. We know Caucasian American patients and Chinese American patients have a higher incidence of wet AMD. But we don’t know, statistically speaking, if you have this gene, what is the chance you will develop wet AMD in your lifetime?
We do know that the data may be biased a little bit by the fact that, on average, Caucasian Americans smoke more tobacco than Chinese Americans, African Americans, and Hispanic Americans. And that tobacco use, as a behavioral confounder, will significantly increase the risk of wet AMD development.
So we can look at genetics from a statistical standpoint, but it’s really hard to parse out the other environmental and behavioral effects that influence the development of wet AMD.”
Why do you think, on average, more women than men are affected by wet AMD?
Dr. Murtaza Adam:
“Women and men have different genetics, and women on average live 5% longer than men. Given that age-related macular degeneration is highly linked to aging and oxidation, women are more likely to develop wet AMD and carry a little bit more burden of the disease, statistically speaking.”
Are there lifestyle and environmental factors that increase one’s risk of developing wet AMD?
Dr. Murtaza Adam:
“There are many studies that describe how behavioral and lifestyle factors are associated with the development and advancement of wet AMD. It’s a very difficult topic to study because it’s really an all-encompassing area of examination. How do one’s daily dietary intake, exercise, and sun exposure come into play?
But we do know that there is a really good level of evidence from the AREDS (age-related eye disease study) trials that were developed by the National Institute of Health, which ultimately led to the development of the AREDS vitamins, which are universally recommended to reduce the risk of macular degeneration advancement.
Those trials combined with many prospective and retrospective trials have shown that a diet high in saturated fat is a risk factor for the development of advanced macular degeneration. In addition, we know that smoking tobacco causes oxidative stress and can lead to a much-increased incidence of wet and advanced dry age-related macular degeneration.
There is also a lot of data looking at the Mediterranean diet, and the antioxidant components of the Mediterranean diet, such as leafy greens and other vegetables high in antioxidants, and Omega-3s from fish—all of those things can protect you against the development of wet AMD and advanced dry AMD.
Also, low exercise contributes. Patients who don’t exercise regularly have higher levels of C-reactive protein and other markers of inflammation in their bodies. And that inflammation translates into oxidative stress for cells and likely does, to some degree, impact the outcomes for patients with dry AMD. So, in the end, what you eat and what you do on a daily basis can impact your prognosis.
I have many patients in my practice who do everything right but are actively going blind. It’s a very frustrating process for me as a physician. It’s even more frustrating for my patients and their families. Unfortunately, the two risk factors that they have zero control over—their age and their genetics—are the number one and two risk factors for AMD.
So, we can wax poetic about all the different things that we can do on a daily basis to reduce our risk, but we really need to get to the root of the problem. How do we reduce the age-related processes that happen in the eye, and how do we counteract the genetic predisposition that people have in a way that protects them against vision loss? And those are the big questions we need to answer as retina specialists other than just injecting eyes every day.”
Responses have been condensed and lightly edited.