Age Related Macular Degeneration
Age-related macular degeneration (AMD) is the most common cause of vision loss in individuals over the age of 50. The name of the condition derives from its cause: damage to the macula, the most sensitive spot on the retina, required for clarity in the center of the visual field. The macula transmits electrical signals through the optic nerve to the brain. Damage to the macula results in retinal tissue degeneration that gradually worsens, diminishing or destroying central vision.
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.
Types of AMD
There are two types of macular degeneration: dry, or non-neovascular/atrophic and wet, or neovascular/exudative.
- Dry Macular Degeneration: Dry AMD is much more common than wet AMD. The dry form is a more gradual process and has three stages: early, intermediate and advanced. Symptoms include thinning of the retina, loss of retinal pigment and the formation of small, round particles inside the retina called drusen. Vision loss with dry AMD is slower and often less severe than with wet AMD. About 90 percent of patients with AMD have the dry form.
- Wet Macular Degeneration: Wet AMD is an advanced form of AMD. The wet form is a rapid process and is characterized by the leakage of blood and fluid, or the growth of blood vessels under the macula to compensate for the blocked arteries. The leakage distorts vision and when the blood dries, scar tissue forms on the retina. This creates a dark spot in the patient's vision. Patients who develop the wet form typically have had the intermediate stage of the dry form of AMD. About 10 percent of patients with AMD have the wet form.
Risk Factors for AMD
Age-related macular degeneration typically occurs in people age 50 and older. Possible risk factors include:
- Exposure to sunlight
- High blood pressure
- Elevated cholesterol levels
- Poor dietary habits
Symptoms of AMD
Symptoms of macular degeneration may include:
- A gradual loss of ability to see objects clearly
- A gradual loss of color vision
- Distorted or blurry vision
- Dimmed vision
- A dark or empty area appearing in the center of vision
- Wavy lines in the vision
Diagnosis of AMD
After performing a medical examination of the eyes, the physician will perform some of the following diagnostic tests:
- Visual acuity test
- Dilated eye examination
- Optical Coherence Tomography (OCT)
- Fluorescein angiogram
- Test for central vision loss
Treatment of AMD
There is no cure for AMD. Recent developments in ophthalmology allow doctors to treat many patients with early-stage AMD with the help of lasers and medication. With regular eye exams macular degeneration can be detected early, allowing for proper treatment and preventing permanent vision loss. Some of the treatment methods used to slow the progression of AMD include:
- Anti-vascular endothelial growth factor injections
- Laser therapy
- Laser surgery