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How Age-Related Macular Degeneration and CNVM Affect the Layers of the Retina

Updated on June 23, 2017
Daughter Of Maat profile image

With over two decades of experience in medicine, Melissa Flagg writes patient information articles, keeping you informed about your health.

Retina Cell Structure

Source

Age-related macular degeneration, sometimes called AMD or ARMD, is a disease that not only destroys vision, but lives as well. Many patients with this disease suffer from depression and disconnection from family because they can no longer see the faces of loved ones.

This disease affects the macula, which is the area of the retina that allows us to read, work on a computer, crochet or knit, and see facial features, among other activities that involve central vision.

Peripheral vision remains untouched, so the patient never goes completely blind. AMD is caused by the aging process. As we get older, hyaline deposits, known as drusen, form under the retinal pigment epithelium (RPE) layer (the layer that focuses images) in what’s called Bruch’s membrane. Bruch’s membrane separates the choroid layer, the layer that provides the blood vessels for the retina, from the RPE layer.

Some Quick Biochemistry

The RPE layer deserves a bit of explanation. It has many functions, but the one that pertains to AMD is phagocytosis. Phagocytosis is a type of endocytosis.

Endocytosis is, essentially, a process of taking out the cellular garbage. Specifically, in the macula, the RPE layer is in charge of “sanitation.” It removes free radicals, dead cells, and other foreign materials from the layer below it, known as the choroid. The immune cells, called leukocytes, are the “sanitation engineers” in our garbage analogy. They are white blood cells that perform the necessary functions of phagocytosis.

What AMD Does: The CNVM

In the dry form of AMD, one theory is the immune system mistakes retinal cells for foreign bodies, or dead cells, and attacks and destroys them, leaving the free radicals and dead cells to collect into solid deposits, or drusen.

All of us will have some drusen at some point in our future, and most of the time it won’t affect the vision. However, in AMD there are many drusen deposits, and it causes a separation between the RPE layer and the blood vessels in the choroid. This separation will force new blood vessels to grow, in order to accommodate the lack of blood flow caused by the separation. This is called a choroidal neovascular membrane, or CNVM.

Unfortunately, these blood vessels tend to be frail and they break down and start to leak blood into the space between the RPE and choroid layers. This is when dry AMD converts to wet AMD. Wet refers to the bleeds caused by the new vessels.

Drusen in Macular Degeneration

Source

Fluorescein Angiography

An image of a normal fluorescein angiogram
An image of a normal fluorescein angiogram | Source

Testing and Detection

New technology has made it easier for ophthalmologists to detect AMD earlier. The advent of optical coherence tomography, or OCT, scanners was paramount in facilitating detection. These scanners show a cross section of the retinal layers making it easy to see any abnormalities before they cause significant damage (see photo).

Fluorescein angiograms are still the gold standard for detecting wet AMD. A yellow dye, fluorescein, is injected into the patients are and pictures are taken at specific intervals with a special filter on the camera. The images are in black and white and are used to see bleeding from frail vessels (see photo).

OCT Testing

An image of an OCT scan, the fovea is the center of the macula.
An image of an OCT scan, the fovea is the center of the macula. | Source

Treatments

Wet AMD does have treatments. I was lucky enough to work for a retinal specialist for over a year, who really knew the research on why the drugs worked. He was a complete jerk, and had absolutely no integrity, but he knew the science.

The main drug therapies available are Avastin (Bevacizumab), Macugen (Pegaptanib Sodium), and Lucentis (Ranibizumab). Lucentis is the most expensive, and is fairly effective, as is Macugen. Avastin, however, shows the most promise and is the cheapest of the three.

Avastin was originally developed by Genentech as an anti-cancer drug. In cancerous tumors, a similar phenomenon occurs. In order for the tumor to keep growing, it needs a blood supply. So, the vascular endothelial growth factor, or VEGF, protein is activated and new blood vessels are formed to feed the tumor. Avastin, Lucentis, and Macugen all inhibit this response. In AMD, this usually halts further deterioration and in some cases reverses the damage already done.

How the Drugs Are Administered and Their Results

These drugs are administered by an ophthalmologist, usually a retinal specialist, in the office. Unfortunately, it’s done by an injection into the eyeball itself. The eye is properly anesthetized first, but there is usually some discomfort after the procedure which mainly comes from the anesthetic.

The numbing gel causes the eye to become quite dry and this can last for several days after the injection. The only real treatment is artificial tears. I told my patients to use tears every hour once they arrived home until they went to bed. This would help rinse the excess numbing medication out of the eye and alleviate discomfort.

The results of these drugs are amazing. I’ve seen patients go from 20/400 to 20/25 after one treatment. This kind of improvement is rare; most patients see improvement of about three or four lines on the vision chart, but for these people, any improvement is greatly appreciated.

The majority of these patients were avid readers, or did quite a bit of work up close and since their diagnosis, they’ve been unable to do things they used to enjoy. So many patients have told me that listening to an audiobook is just not the same, and they terribly miss being able to pick up a book and read for hours.

Vitamins

Vitamins have shown great promise in the protection against the development of the disease and are the only treatment available for dry AMD. Ocuvite and Preservision, both made by Bausch and Lomb, are the leading vitamins on the market for the disease. They are also the most widely recommended by ophthalmologists.

The vitamin formula is known as the Age-Related Eye Disease Study, or AREDS, and it contains vitamin A, vitamin C, lutein, vitamin E, zinc and copper.

There is a new version of the vitamins called the AREDS 2 formula, which is part of an ongoing study set to be finished in 2013. This formula is a bit different. It eliminates the vitamin A, and adds zeaxanthin (pronounced “z-a-zan-thin”), and the Omega-3 compounds DHA and EPA.

The study is attempting to determine if reducing the amount of zinc, and eliminating vitamin A, while adding the Omega-3’s and zeaxanthin will change the effects the vitamins have on the disease. Vitamin A was eliminated mainly because smokers can’t take the supplement due to the increased risk for lung cancer it may cause.

The earlier the vitamins are started, the better. Antioxidants are the primary compounds that prevent and halt AMD. Vitamins are a good source, but diet is better. A diet rich in leafy green vegetables, nuts, and fish will supply the same vitamins and minerals found in the AREDS vitamins and they will be all natural making them easier for the body to absorb.

The Amsler Grid

An Amsler Grid
An Amsler Grid | Source

Prevention

AMD needs to be caught in its earliest stages to prevent damage. It is recommended that patients who may be predisposed monitor their vision at home using an Amsler grid (see photo).

People who may have a predisposition include those who have been exposed to excessive sunlight without the protection of sunglasses, smokers, those with a family history, those with hypertension, diabetes or who have a high fat intake, and Caucasians.

The Amsler grid should be used by these individuals daily in order to catch any changes immediately. The grid is held at 14 inches with glasses. The patient looks through their bifocal (if they have bifocals) and covers one eye. While looking at the small black dot in the center of the grid, the patient needs to observe if the lines of the grid around the dot are missing, wavy, or distorted in any way.

It is important to look only at the central dot and to not move the eye as movement may cause a false distortion. The patient then tests the other eye the same way. If changes are noticed, you should call your ophthalmologist immediately.

In Summary

AMD is a devastating disease, and it can easily ruin quality of life. There are treatments, but the key is prevention and to catch the disease in its earliest stage. Always wear sunglasses ANYTIME you go outdoors (even if it’s a cloudy day); eat a diet rich in leafy green vegetables, nuts, and fish, or take vitamins; don’t smoke; and after the age of 45, check your vision with an Amsler grid at least once a week. If you notice any changes in your vision, either with or without the Amsler grid, you should contact your ophthalmologist right away.

© 2012 Melissa Flagg OSC

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    • Daughter Of Maat profile image
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      Melissa Flagg OSC 12 months ago from Rural Central Florida

      It is unusual for someone to develop CNVM in their 40's. In answer to your question, you won't ever go completely blind. You'll always have peripheral vision, but you won't be able to see directly in front of you. Typically, you'll develop dry AMD in the good eye before wet AMD (CNVM). So if you have not yet developed dry AMD in your good eye as of yet, chances are high you won't develop CNVM in that eye anytime soon. Make sure you're taking plenty of antioxidant vitamins such as the B&L AREDs 2 formula eye vitamin, fish oil and vitamin C. Hope that helps.

    • profile image

      Norma Scillieri 2 years ago

      Hi, I was diagnosed with CNVM wet macular in 2007, i went from 20/20 to almost blind on my right eye overnight , I do remember I had bronchitis , started immediately with injections ugh for 5 years no improvement, my question is , it started in my 40s , which is rare, I'm doing fine with one eye, but can I go blind? Can this Wet CNVM move to the good eye? My dr is confident it won't .

    • Daughter Of Maat profile image
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      Melissa Flagg OSC 3 years ago from Rural Central Florida

      I would get a second opinion. CNVM is typically very distinctive. Make sure you see an ophthalmologist, preferably a retinal specialist.

    • profile image

      md kabir 3 years ago

      I have been diagnosed for a suspected cnvm but the doc is not sure if it's a cnvm or not??

      what should i do????

    • profile image

      Chiranjeev 5 years ago

      thanks for good advice.

    • Daughter Of Maat profile image
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      Melissa Flagg OSC 5 years ago from Rural Central Florida

      Many things can cause a CNVM, not just macular degeneration. I'm not familiar with your specific case so I can't give you specifics. There is no cure, and you're already undergoing the best treatments on the market. The only other thing you can do is completely change your diet. A diet rich in leafy green vegetables, fruits, and nuts provides all the vitamins and antioxidants the body needs to prevent further damage. For more information on a diet that helps in preventing further damage see my other hub: The Plant-Strong Diet: Vegans and Vegetarians.

      At your age, there has to be a systemic cause of the CNVM, assuming you have not yet been diagnosed with anything, if you haven't had blood work done lately, you should. Without knowing more of your history, I'm not able to suggest any other treatments. If your vision is blurry, you should see your doctor. Blurry vision after an injection is not uncommon however.

    • profile image

      chiranjeev 5 years ago

      hi all,

      From last 3 years(sept.2009)(28 age),i'm suffered from CNVM IN RIGHT EYE.

      so please suggest me the cure and causes of this diseases.

      Already tken 4-avastin and 3- lucentis injection,now today my vision is again blurred. so plz suggest me.

      WAITING FOR POSITIVE COMMENTS.

    • JamaGenee profile image

      Joanna McKenna 5 years ago from Central Oklahoma

      Is there anything for which there isn't an app these days? lol!

    • Daughter Of Maat profile image
      Author

      Melissa Flagg OSC 5 years ago from Rural Central Florida

      lol nice, there's always an app for that! ;)

      Actually there is an app for the amsler grid.... lol

    • JamaGenee profile image

      Joanna McKenna 5 years ago from Central Oklahoma

      Penny already has a program called "Zoom" that magnifies print on the screen, so I'm guessing AMD Vision Control is a newer version. Don't know if it's part of "Zoom", but her computer is also equipped with a computer-generated voice that reads out loud whatever is on the screen. Absolutely useless for surfing the net, though. Bogs down trying to decipher URLs. Oh well, it was a thought. Thanks! (But if you ever lose your vision to AMD, you'll know...there's an app for that. Sorry, couldn't resist...) ;D

    • Daughter Of Maat profile image
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      Melissa Flagg OSC 5 years ago from Rural Central Florida

      Apparently it has to do with my video card, but there is an option on it to magnify the screen, and it looks a bit like the machines AMD patients use for reading regular print books. I'm not sure all computers would have this, but it REALLY magnifies it!

    • JamaGenee profile image

      Joanna McKenna 5 years ago from Central Oklahoma

      Great! But I'll still google it. Two heads and all that. ;D

    • Daughter Of Maat profile image
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      Melissa Flagg OSC 5 years ago from Rural Central Florida

      Awe, thanks JamaGenee! I'm going to actually run the program on my PC, because now I'm curious... if it really makes a difference I'll have to update the hub with information on it! :D

    • JamaGenee profile image

      Joanna McKenna 5 years ago from Central Oklahoma

      I'll have to google "AMD Vision Engine Control Center" and find out what it does! Thanks!

      As for making this hub simpler to understand, no need for that. It's fine as it is! There's absolutely nothing wrong with making us stretch our brains a bit. Lord knows mine gets stretched on a regular basis by an 86-yrs-young "old and blind" lady in MO! ;D

    • Daughter Of Maat profile image
      Author

      Melissa Flagg OSC 5 years ago from Rural Central Florida

      I may need to re-read the article an attempt to be more explanatory. I have a tendency to get into medical jargon and forget not everyone understands this. lol

      As for your 86 yr old friend, she is the exception. Most patients become extremely depressed, but there a few who don't let it get them down and still live their life to the fullest. As for the computer work, I just recently got windows 7 on a new laptop and I found a setting for AMD. It literally says AMD VISION Engine Control Center. I haven't used it simply because since I'm not in the field anymore I don't need to know about it, but it may help her to be able to use the computer. I know you don't mind helping her, but it may give her more of the independence she craves. I'm glad she's doing well, this disease can really ruin quality of life.

    • JamaGenee profile image

      Joanna McKenna 5 years ago from Central Oklahoma

      My 86-yr-old friend Penny lost most of her sight to macular degeneration about 10 years ago. Growing up during the Depression, her diet was definitely lacking in essential nutrients. According to her doctor, this is the cause of her mac degen, which is now common among others of her age group who also lacked proper diets in childhood due to the Depression. Far as I know, though, there's nothing that can be done to reverse the damage. As a former RN, if there were, she would've found it years ago, so I'm 99% sure she's never had the shots to the eyeball.

      Another, much younger, friend gets those shots regularly, to prevent further macular degeneration caused by the steroids prescribed 15 years ago when she was first diagnosed with MS. Of course, it's now known steroids cause more harm than good for MS sufferers.

      The 86-yr-old friend, oddly, is not the least depressed other than the expected "down" from not being able to see to do the things she enjoys. She reads constantly, either via audiobooks or the volunteer reader who visits once a week. Family, friends, and neighbors take her places and "see" for her. She has a special program on her computer for sending and receiving email, but so far there's no program to make it possible for her to surf the net and look up information. Instead, she keeps me busy looking up information for her, which you betcha has greatly expanded my horizons! She'll say "Do you know anything about [insert subject]?" and I'll reply "No...but I'm sure I'm about to know a lot". lol!

      Thank you for the information in this hub! Although I've worked in a medical center, I don't understand all of it, but do appreciate the effort it took to write it!

      Voted up, useful and awesome!

    • Dale Hyde profile image

      Dale Hyde 5 years ago from Tropical Paradise on Planet X

      Most informative hub with some very well done research! I visit you hubs and always learn more and more! Keep up the excellent work! Voted up, interesting and useful.

    • phoenix2327 profile image

      Zulma Burgos-Dudgeon 5 years ago from United Kingdom

      Very well written and informative. Voted up, interesting, and useful. Also shared socially.