In this MD Newsline exclusive interview with vitreoretinal specialist Dr. Michael Singer, we discuss what wet age-related macular degeneration is and why it matters.
Can you explain why age-related macular degeneration (AMD) in general, and wet AMD in particular, are such important health issues?
Dr. Michael Singer:
“The reason macular degeneration is such an important health issue is basically, as more baby boomers get older, the incidence of macular degeneration is going to significantly increase.
Vision is extremely important to people. Vision is what people use to keep their independence. People talk about they’d rather have cancer than lose their sight. Sight gives you the ability to read, gives you the ability to drive, gives you the ability to recognize other people. So, I mean, when you lose your sight, it’s a very big deal.
We talk about two types of macular degeneration. There’s basically two types. There’s dry macular degeneration, and in dry macular degeneration, there is a slow and steady loss of vision. This is a gradual process. It happens over years and may not be immediately apparent. People tend to report that ‘My vision’s gone down,’ but can’t really tell you when it happened.
When you look at the incidence of dry macular degeneration, in terms of age, you’ve got a one out of ten chance of getting dry macular in your sixties, a one out of four chance in your seventies, a one out of three [chance] in your eighties, and so on. And in these patients with dry macular degeneration, 10% will end up converting to a type of macular degeneration called wet macular degeneration, which is a much more abrupt loss of vision.
The best analogy I can give you for macular degeneration is I tell people they’re like a carpet. The carpet wears down over time, and as it starts wearing down, you start to see the baseboard underneath. The patient’s vision isn’t as good as it used to be, but the process is gradual. In this analogy, sometimes, when the carpet wears away, it actually hits a pipe. If it hits a pipe, you have a major flood.
In terms of the eye standpoint, hitting a pipe is basically involving a blood vessel. So as dry macular degeneration starts to wear away, and it hits a blood vessel, and it starts to bleed, and all of a sudden the vision goes down quickly or abruptly, and now you’ve got the patient’s vision significantly down, and this loss of vision can lead to scarring, and that’s called wet macular degeneration.”
How does central vision loss manifest in wet AMD? What factors impact how rapidly patients experience vision loss?
Dr. Michael Singer:
“Loss of central vision occurs differently in dry vs. wet macular degeneration. I like to refer to dry macular degeneration as ‘slow and steady,’ in that one person’s vision goes down slowly over time. I like to refer to wet macular degeneration as ‘fast and ugly,’ in that a patient’s vision goes down very quickly over a matter of days or weeks.
Patient will say with wet macular degeneration, ‘everything was fine, and all of a sudden my vision got blurry.’ And depending [on] how big it is, it could be a small area that’s out of focus, or a larger area that’s out of focus.
People use a screening tool called an Amsler grid, which is like a checkerboard that they use with early dry macular degeneration, to help monitor the conversion from dry to wet macular degeneration. There are now more sophisticated technologies being developed to detect this conversion even earlier.
The goal is [that], the earlier you can detect the conversion from dry to wet macular degeneration, the earlier you can treat it. The earlier you can treat it, the more vision you can preserve.”