Stages of Age-Related Macular Degeneration (AMD)
Age-related macular degeneration (AMD) is diagnosed by a comprehensive eye exam and other testing. During your visit, your doctor will check vision and dilate your eyes to look for drusen, which are yellow deposits underneath the retina. Your doctor may also perform photographs or scans of the retina. While some small drusen are a normal part of the aging process, many drusen or medium-to-large drusen might suggest the presence of AMD.1
What are the stages of macular degeneration?
There are three general stages of AMD, partly based on the size and amount of drusen found under the retina on examination. You can have AMD in one eye only, or have different stages of AMD in each eye. You may have heard of “dry” and “wet” AMD; dry AMD is classified into early, intermediate, and advanced stages. Wet AMD is always considered advanced.
In early AMD, there is usually no vision loss, and there are small or few medium-sized drusen, which are about the thickness of a human hair.1 With early AMD, there is a low risk of progressing to advanced AMD within the next 5 years.2 Even after 10 years, one study found that only 15% of people with no drusen or small drusen at diagnosis went on to develop large drusen.2
This diagnosis is important to recognize because individuals with intermediate AMD are at significant risk for developing advanced AMD. In intermediate AMD, there may be some or no vision loss. In this stage, there are either multiple medium-sized drusen, or at least one large drusen, in one or both eyes, along with changes in the retinal pigment epithelium (RPE), which are cells underneath the retina that support the health of the retina.2
Macular degeneration progression
Having large drusen in both eyes makes it more likely that one will develop advanced AMD within 5 years than having large drusen in only one eye (26% and 6.3%, respectively).2 In those with medium drusen at baseline, 37% went on to develop large drusen if they were only in one eye; and 71% developed large drusen if they were in both eyes, at the 10-year follow-up.2
Assessing risk of AMD progression
A simple scoring system was developed in 2005 to assess for AMD risk progression based on two main factors: the presence of one or more large drusen and the presence of pigmentary changes.2 Patients who are affected are assigned 1 point for each risk factor present, then the points are added together for both eyes, resulting in a 5-step grading scale (0-4). The doctor can then provide an approximate 5-year and 10-year risk of developing advanced AMD in at least 1 eye.2
|Risk Factor Score||5-Year Risk||10-Year Risk|
Individuals with advanced AMD often have changes in their vision because of macular damage. Having advanced AMD in one eye increases your risk of developing advanced AMD in the other eye.1 There are two kinds of advanced AMD: dry AMD (also called non-neovascular AMD) and wet AMD (also called neovascular or exudative AMD).
Advanced dry AMD
In dry AMD, the retinal cells that are sensitive to light gradually break down, interfering with the eye’s ability to sense light. This breakdown, along with degeneration of the underlying tissue that supports the retina, called the retinal pigment epithelium (RPE), causes vision loss. Geographic atrophy is the term used to describe an area in which the RPE cells have completely died.
Advanced wet AMD
In this kind of AMD, abnormal blood vessels develop underneath the retina, which can be damaging if they leak fluid or blood.1 While the effects of dry AMD can be more slow and gradual, the course of wet AMD can progress quickly and vision loss can be sudden if there is leakage or bleeding underneath or into the retina. It’s important to note that while dry AMD has various classifications (early, intermediate, and advanced), wet AMD is always advanced. It is also possible to have characteristics of both wet and dry AMD in the same eye.1
If you’ve been diagnosed with AMD, talk with your doctor about the diagnosis and what it means for your risk of disease progression, as well as treatment options. While there is currently no treatment for early AMD, your doctor might be able to provide you with suggestions on how to promote and maintain your eye health and protect your existing vision. If you’ve been diagnosed with intermediate or late AMD, talk with your doctor about the potential course of the disease, >what you might expect, and what treatment options are available to you. This can help you make decisions about what treatments are best and how to compensate for any vision impairment you might be experiencing.