Diseases
Overview
Age-Related Macular Degeneration
Diabetic Retinopathy
Retinal Vein and Artery Occlusions
Flashes of Light and Floaters
Retinal Tears and Retinal Detachments
Macular Pucker (Epiretinal Membrane)
Macular Hole
Vitreomacular Traction
Uveitis (Inflammation in the Eye)

Age-Related Macular Degeneration

What is Macular Degeneration?
Age-Related Macular Degeneration (AMD) is a degenerative condition involving the retina in the central area known as the macula. In most cases, the central damage is very mild and the vision is normal, but in advanced cases the central vision can be completely lost. Visual tasks that require detail are affected the most, making some daily activities very difficult. AMD, even in advanced disease, does not lead to total blindness as the peripheral vision is unaffected. Being able to retain peripheral vision keeps patients independent even if the vision loss is severe.


What is “Dry” or “Wet” Macular Degeneration?
There are two types of macular degeneration, “dry” and “wet”. Dry AMD, or non-exudative AMD, is characterized by the buildup of waste by-products from normal retinal metabolism in small collections called drusen and can be detected on routine examination of the retina. All patients with AMD start as dry and in the earliest forms of the disease, drusen are present but do not cause compromise of the vision. Over time, the number and size of the drusen can increase and the retina overlying the drusen can become increasingly atrophic with a decrease in visual function. When the atrophic retinal areas coalesce, the areas become known as geographic atrophy. If areas of geographic atrophy affect the center of the macula the vision can be significantly affected.



At any time during the disease there can be a change to exudative or “wet” AMD. Wet AMD is characterized by the development of abnormal blood vessels from the layers beneath the retina. These blood vessels are termed neovascular membranes, and will leak fluid, protein, and often blood beneath the retina and into the retina itself. When the process begins there may be only a mild disruption to the retina that appears as distortion in the vision. With increasing severity, the distortion can turn into a blind spot affecting the central vision as scarring develops. The vision loss from this form of AMD is much more rapidly progressive than the dry form.



Who gets AMD?
The development and progression of AMD is determined by multiple factors both environmental and genetic. There are hereditary components to AMD and can run strongly in families but is not solely determined by genetic makeup. Environmental factors play a role in the progression of disease, in particular smoking. People who smoke are significantly more likely to progress to advanced disease than those who have never smoked. Anyone who regularly smokes is strongly advised to stop to reduce the risk of progression as well as for the other substantial health benefits. Additionally, patients with elevated cholesterol and blood pressure are at increased risk. The greatest risk factor is advancing age, rarely do people under 50 years old have evidence of the disease.


What do I watch for?
The progression of dry AMD is slow and typically the only symptom is blurred vision. If geographic atrophy develops, a dark or gray spot in the vision may become visible, if wet AMD develops, vision can become distorted. To monitor changes, an Amsler grid can be used to self-assess at home. 
 
To use the Amsler grid: 
1. Each eye is checked individually, with glasses, from about 12 to 15 inches away
2. While looking at the central dot assess the grid pattern for any distortion, waviness, darkening, or missing areas. 
3. Check the eyes at least 1 time per week. 
4. Place the grid somewhere that it can be easily seen, like on the bathroom mirror. If it becomes part of your routine, it is easier to remember. 

Similarly, other straight lines may appear distorted such as door frames, window blinds, and highway stripes. With the development of any of these changes, a repeat examination should be performed immediately to assess the retina for any signs of wet AMD. Treatment should be initiated as soon as possible to minimize any damage.


How is AMD diagnosed?
The most importance part of making the diagnosis of AMD is a thorough examination of the retina through a dilated pupil. To aid in the diagnosis, a scan of the retina is typically performed with Optical Coherence Tomography (OCT), this allows the retina to be seen in cross-section to better evaluate any retinal damage. The OCT scan can also be used to follow the response to treatment by creating detailed measurements of the retina. Another important diagnostic test is Fluorescein Angiogram (FA), which allows the visualization of blood flow through the retina and can characterize the neovascular membranes by the size, type, and activity. Many different retinal diseases can present as fluid or blood in the retina and neovascular membranes, it is important to have a complete exam by an experienced Retina Specialist to ensure the correct diagnosis.
 
Wet AMD with subretinal scarring and intraretinal fluid

Dry AMD with subretinal drusen

Fluorescein angiogram showing wet AMD

How do you treat AMD?
There are no current treatments for dry AMD to halt the progression or reverse the damage of the disease. We can try and control the environmental factors that promote progression. Most importantly is stopping smoking, active smokers are more than twice as likely to develop vision loss from AMD. Nutritional factors can play a role as well. In 2001, as a result of the Age Related Eye Disease Study, results were published that found with dietary supplementation of Vitamin C, Vitamin E, beta carotene, Zinc, and copper there was a decrease in the risk of developing advanced AMD by 26%. These vitamins are sold as AREDS formula from multiple different manufacturers. In 2013, the AREDS 2 study was published removing beta-carotene and adding lutein and zeaxanthine with continued benefits.
 
Wet AMD now has multiple treatments to stabilize the disease. Previously, to treat neovascular membranes thermal laser was used to destroy the membranes but also significantly damaged the overlying retina. Medical treatments were developed, refined, and in 2006, ranibizumab (Lucentis), was FDA approved for the treatment of wet AMD. This medication is an antibody against VEGF, the molecule responsible for the development of the abnormal blood vessels characterizing this form of the disease. This medication, and its related medications bevacizumab (Avastin) and aflibercept (Eylea), have revolutionized the treatment of wet AMD. Now, instead of developing a large central blind spot the vision can be stabilized in over 90% of the time and about 1/3 of patients have visual improvement.

Data from Lucentis (ranibizumab) clinical trial
 
As a class these medications are called anti-VEFG’s and are administered by Intravitreal Injection into the eye every month to control the activity of neovascular membranes. Depending on the response, the interval between the injections can be lengthened. These medications are excellent treatments but do not cure the disease, with this in mind the duration and number of treatments needed cannot be predicted.   
 
Dr Kruti Dajee Dr Jawad Qureshi Dr Johnathan Warminski