QUESTION: I have dry AMD. Will it turn to wet?
ANSWER:
Not everyone with AMD progresses to wet AMD. There is another FAQ with details about the risk of vision loss from AMD. Briefly, if you have early or intermediate dry AMD, your risk of progressing to wet is 10-14 or 15 %. That means that 85-90% of all people with AMD have the dry kind, so that’s the majority. Wet AMD is in the minority and rare, but if left untreated it can quickly cause central vision loss.
Parts of the Retina
Let’s review the parts of the retina that are involved in AMD. From top to bottom there are the Photoreceptors (rods & cones) that convert light to sight, RPEs that take care of the Photoreceptors, Bruch’s Membrane, and the blood supply in the Choroid.
How and Why The Process Starts
VEGF (Vascular Endothelial Growth Factor) is a protein produced from cells that causes new blood vessels to develop when needed, such as after an injury or lack of oxygen. In most places in the body, that’s a good thing. But not when it happens in the retina.
Photoreceptors, RPEs and Angiogenesis
All AMD starts as dry even if it’s not diagnosed until it’s wet. As the disease progresses, drusen (we call it ‘eye poop’) builds up and can weaken Bruch’s Membrane. This causes inflammation which signals the release of VEGF. This process is called angiogenesis (‘angio’ refers to blood, ‘genesis’ refers to development of something).
These unwanted blood vessels grow through the weakened Bruch’s Membrane into the area of Photoreceptors and the RPEs.
Wet AMD and CNV
This process is called wet AMD and CNV (Choroidal Neo-vascularization refers to the Choroid, ‘neo’ refers to new, and vascularization refers to blood vessels).
Wet AMD is Exudative Macular Degeneration
Those new blood vessels are fragile and can leak fluid, can rupture and leak blood, or both. That’s where the ‘wet’ descriptor came from. These fluids are ‘edudates’ which is why sometimes you’ll see wet AMD referred to as Exudative AMD and dry as Nonexudative AMD. CNV can occur in any form of macular degeneration.
Symptoms from Wet AMD/CNV
For normal vision, the macula needs to be flat. The blood or fluid collects in something similar to a blister which distorts vision and causes a person to see wavy lines and have other distortions. Have you ever had a drop of water fall on a piece of paper with writing? It distorts what is under it, right?
Make sure if you have any changes in your vision that you contact your eye doctor as soon as possible. Research has shown that the sooner treatment is started, the better the prognosis.
Inflammation
This buildup of fluid or blood causes inflammation (edema) and can form scar tissue which cannot be removed. It can also cause damage to the RPEs, so they’re not able to keep the Photoreceptors working well. It can also kill the RPEs. If the RPE dies, the Photoreceptor dies, and central vision loss occurs. That’s why it is so important to get treatment as soon as possible!
The Injections
The medications that are injected into the eye are called anti-VEGF because they block the further release of VEGF. They are also called angiogenesis medications. That stops new blood vessels from growing. You might think of a VEGF protein as a lock. The anti-VEGF medication puts the key in the VEGF lock to stop it.
Current Anti-VEGF Medications
The current anti-VEGF medications are Lucentis, Eylea, Avastin, and Beovu. For some people, the disease is slowed down by repeated treatments. For some, vision improves. Everyone is different.
‘Dried Up’ is not Dry AMD
The blood and/or fluid is then reabsorbed by the body. That’s why you’ll hear the retinal specialist say that the eye is ‘dried up.’ That’s not the same as dry AMD. Wet AMD cannot go backwards, but sometimes it goes into something similar to remission and can remain stable. You always have to be diligent to check your vision and report any changes.
The anti-VEGF medications wear off quickly, so repeated injections are necessary.
New and Better Treatments on the Horizon
There is a lot of research related to wet AMD/CNV. New treatments will extend the time between them and replace injections with eye drops and oral medications. It’s the drops and pills that many people are looking forward to! You can find out more in the article ‘Have Wet AMD and Hoping for Something Other Than Injections?’
Even better, with gene therapy, a ‘one-and-done’ treatment may stop the disease entirely. There’s more about this in ‘Gene Therapy Research for AMD.’
Great Resource
One of the best sources of information about AMD is from the Angiogenesis Foundation’s site ‘Science of AMD.’ There you can find text explanations with audio available, colorful illustrations, videos, and brochures. They are a not-for-profit site, so they don’t sell anything. That’s a good indication that their information is not biased.
There is an excellent infographic explaining the angiogenesis of AMD.
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