AMD
Meaning of AMD: Reading, driving and recognizing faces all rely on the macula, and AMD is a leading cause of central vision loss in later life.
Definition of AMD
AMD, short for age-related macular degeneration, is damage to the macula, the small central patch of the retina that supplies sharp, detailed vision. It builds up gradually and mainly affects older adults, blurring or blanking out the center of the visual field while the surrounding peripheral vision is usually left intact.
What is the difference between dry and wet AMD?
| Dry, or non-neovascular | Wet, or neovascular | |
|---|---|---|
| What happens | Yellowish deposits called drusen collect beneath the retina and the supporting pigment layer thins | Fragile new blood vessels grow up from the layer beneath the retina and leak fluid or blood |
| How common | The large majority of cases | The smaller share, but the cause of most severe vision loss |
| How fast | Slow, often over years | Can change vision within days or weeks |
| Advanced form | Geographic atrophy, patches where the light-sensing tissue has died | Scarring under the macula once leakage settles |
Dry AMD can turn into the wet form, so the two are stages of one process rather than separate diseases. Early dry changes often cause no symptoms at all and are picked up when the retina is examined for another reason.
How does it change vision?
The macula handles fine detail and color, so its loss shows up first in tasks that need precision: reading small print, threading a needle, recognizing a face across a room. Straight lines can look bent or wavy, a distortion that often signals leakage. Later a blurred or dark patch sits in the middle of the view and moves wherever the eyes look, which is what makes it so obstructive. Peripheral vision comes from the rest of the retina and is generally spared, so people usually keep enough sight to move around a familiar room. That pattern separates macular degeneration from conditions such as glaucoma, which erodes the outer field first and leaves the center until last.
What raises the risk?
Age is the strongest factor, and the condition is uncommon before later middle life. Smoking is the largest changeable risk. Family history matters, and several common gene variants are known to raise susceptibility. Fair complexion, light iris color and cardiovascular risk factors are also associated. Because the two forms progress at such different speeds, an eye examination distinguishes them before any judgment is made about how quickly vision is likely to change.
Also known as
Used in a sentence
The ophthalmologist noted early changes consistent with dry AMD on the retinal examination.
Good to know
Dry and wet AMD differ in mechanism, since abnormal blood vessel growth occurs only in the wet form, and that distinction affects how the condition is monitored and how quickly vision tends to change.