Dr. Amanda Legge (pronounced Leg-ee) is a member of our Facebook group. She’s an Optometrist at the Wyomissing Optometric Center in Eastern Pennsylvania.
I want to summarize AMD as a disease process. I explained this during my Facebook Live talk with Linda on 12/12/2021. I also recommend looking in Guide 2 for “what tests does my eye doctor do to diagnose and manage macular degeneration”. In that post I show what normal retina health and normal OCT looks like in comparison to this post about AMD.
AMD is a disease of the transport process of nutrients in and waste products out of the macula. Oxidative stress and other factors damages the bottom layer of the retina called the RPE (retina pigment epithelium). The RPE has several jobs, but one of its main responsibilities is to help transport waste OUT of the retina, through the RPE, and into the blood vessels below so that the waste is eliminated then with the rest of the waste our bodies produce. It is also responsible for carrying nutrients from the blood vessels under the macula, through the RPE, and INTO the macula where it nourishes the photoreceptors that are responsible for our vision.
The disease of AMD is a fault of this transport system as a whole. Studies show AMD starts 3-5 years before eye doctors can view this clinically in the macula as drusen. An entire wash of waste deposition already builds between the blood vessels and macula as very early AMD starts (shown in electron biomicroscopy of donor eyes, we cannot visualize this yet clinically). As that waste product builds more and more, eventually eye doctors can see the iceberg peaks of that waste deposition that we call drusen. Drusen look like yellow bumps/deposits in the macula during a dilated eye exam.
Drusen can be present for a very, very long time (decades even) in the macula before vision deteriorates. But if the disease progresses, not only is waste not able to escape the retina (and builds up as drusen), it also creates a thicker and thicker barrier for nutrients to get through in order to feed the retina.
Advanced AMD
That is what is at the heart of vision loss in AMD, the photoreceptors are not getting enough nourishment so over time either AMD can progress to advanced dry AMD or turns to wet.
Advanced Dry AMD (often called geographic atrophy) occurs when the photoreceptors don’t get enough nourishment and slowly die off (atrophy) over time until there are no photoreceptors left in large areas of the macula. No photoreceptors = no vision in that area.
Wet AMD occurs also because of lack of nourishment and oxygen to the retina. 15-20% of the time the body decides it’s a good idea to grow NEW blood vessels from the vasculature underneath the retina, through the RPE, and into the retina itself. In theory this sounds good, right? New blood vessels = new route for more nutrients and oxygen to get to the photoreceptors. It is a good idea……but unfortunately it’s only good in theory.
These new blood vessels, known as neovascularization, do not have the same structure as the blood vessels we are born with. They are much more fragile. Because of this they very easily leak and bleed causing fluid and blood to accumulate in the center of our vision which can quickly cause vision distortion or vision loss. So, it makes absolute sense why diet, exercise, control of diseases that affect our vasculature (diabetes, high blood pressure, high cholesterol, obesity, cardiovascular disease as the most common) and supplementation helps to protect the retina.
We can control oxidative stress by providing the retina with the fighting power of antioxidants to protect the RPE from further deterioration and thus less waste deposition.
Exercise helps increase the “push” through that thicker barrier, AMD diet helps feed the retina more nutrients when not enough gets through on its own. Control of vascular systemic conditions helps the blood vessels stay healthy so they can do their job easier of giving nutrients and taking waste. And as AMD progresses, AREDS2 and extra nutraceuticals [medicinal foods supplements, fortified foods, etc] help further boost the amount of good nutrients our macula craves to stay healthy (carotenoids and antioxidants).
It can be hard to change and maintain a healthy lifestyle for the long term. But hopefully understanding this process makes that a little easier when it all makes sense in the end. Have a great weekend everyone!. ~Dr Legge
Written December 7th, 2021.
Images with Dr. Legge’s Notes
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