Macular degeneration, also known as age-related macular degeneration (AMD), is a common condition in older adults and the leading cause of vision loss in people ages 50 and older. Macular degeneration affects the macula, the part of the retina responsible for the crisp, detailed central vision needed for reading or driving.
The speed at which AMD advances is variable. In some patients, the condition progresses slowly and the changes in vision are imperceptible for some time. In others, the disease moves at an accelerated pace, leading relatively quickly to loss of central vision in one or both eyes. While AMD does not result in complete blindness because some peripheral vision always remains, it does make ordinary activities, particularly those that require close visual acuity, increasingly difficult.
Macular degeneration can be classified as either dry (non-neovascular) or wet (neovascular). Dry macular degeneration is the more common diagnosis, and is considered to be an early stage of the disease. This form of the disorder usually develops as the macular tissues thin during aging. Deposits of pigment within the macula may also occur.
In only about 10 percent of patients does the condition progress to the more advanced form of the disease. If this occurs and the patient develops wet macular degeneration, new abnormal blood vessels develop beneath the macula, causing a leakage of blood and fluid. This leakage can lead to the creation of blind spots and permanent damage to central vision. With either type of macular degeneration, peripheral vision is maintained.
There are three stages of AMD. These stages are designated both by signs detected by the ophthalmologist and symptoms experienced by the patient.
During early AMD, the physician can diagnose the illness by the presence of more than the usual number of medium-size drusen (yellow deposits under the retina). Typically, patients with early AMD are not yet experiencing any loss of vision.
When a patient is in the intermediate stage of AMD, the doctor observes large drusen as well as possible changes in retinal pigment. While some patients at this stage may experience small gaps in vision, most patients with intermediate AMD do not experience any significant vision loss.
During late stage AMD, patients have enough damage to the macula to experience significant vision loss. The two types of late AMD are:
In the wet type of AMD, which progresses more rapidly than the dry, the newly developed blood vessels may leak blood and fluid. Visual loss in dry AMD usually occurs more gradually. Ninety percent of patients diagnosed with AMD have the dry variety, but approximately 10 percent of these patients later develop the wet variety of the disorder. Although patients with either type may experience vision loss, wet AMD not only progresses more rapidly, but usually results in greater visual damage.
As people age, everyone is at risk for macular degeneration, but some people are at elevated risk due to genetic and/or environmental factors. Some individuals have a genetic variant known as complement factor H that makes them more likely to develop this condition. Nearly half of the cases of blindness associated with macular degeneration are linked to this genetic deficiency.
Macular degeneration is most common in females and people with light skin or eye color, and the risk for all patients increases as they age. Over 30 percent of adults age 75 and older have been diagnosed with advanced or intermediate age-related macular degeneration.
Other factors that may increase the risk of developing macular degeneration include:
There are three easy ways you can minimize your risk including:
The ophthalmologist may be able to detect early signs of macular degeneration through a regular eye examination while the patient is still asymptomatic. This is one of the many reasons why it is so important to undergo regular eye exams.
In order to definitively diagnose AMD, any or all of the following are necessary:
During the physical examination of the eye, the ophthalmologist takes particular care to look for pigment changes under the retina, as well as for drusen. Treating detecting macular degeneration and other serious eye conditions as early as possible can help to prevent permanent loss of vision.
While there is no cure for macular degeneration, there are several treatment options available to help patients manage this condition and preserve their vision. The best treatment option for each patient depends on the severity and type of the condition, as well as how much, if any, permanent vision loss has occurred.
Traditionally recommended treatments for AMD may include one or more of the following, each of which approaches controlling AMD in a somewhat different way:
