How Dry and Wet Macular Generation Differ

Age-related macular degeneration, or AMD, is a disorder that slowly destroys central vision, making it hard to read or see small details.  It is most commonly linked to patients older than 60. There are two kinds, dry and wet.   An important part of eye care Boulder is checking at-risk patients for signs of either type.

AMD develops in the retina, a structure at the back of the eye that translates images and light into signals that reach the brain.  The portion of the retina known as the macula provides sharp, detailed vision.  Damage to blood vessels that support the macula causes harm to that structure and compromises vision.

Dry AMD

Of AMD sufferers, 90 percent have the dry type.  As it develops, the macula’s layers continue to thin.  They become less effective, a condition called atrophy. 

In the early stages, an eye doctor can see changes in the color of the macula.  Drusen, which are small piles of waste from eye cells, collect on the retina.  They can cause it to atrophy.  Almost everybody who is older than 50 has some drusen. 

Dry AMD does not progress beyond discoloration of pigment.  This form gets its name from the fact that it involves no leakage of fluid from blood vessels in the eye.  Almost all AMD patients initially have the dry form.

Blurred vision is the most common sign.  Eventually, a spot in the middle of the visual field appears darker and bigger.  Anything in the central field of vision might look dim or faded.  Treatment includes a combination of antioxidants, specific vitamins, and zinc.

Wet AMD

One of every 10 cases of AMD is the wet form.  The wet AMD name refers to the fact that blood vessels leak.  Wet AMD occurs when new blood vessels form in the choroid layer, behind the retina.  This development is called choroidal neovascularization.

The new vessels leak blood, other fluids, and lipids.  As the leakage permeates the macula and other layers of the retina, scar tissue forms.  Retinal cells no longer function. 

Sufferers note that straight lines look wavy and distorted.  Central vision loss can be quick.

Among treatments for wet AMD are laser surgery to destroy leaking vessels and painless eye injections of medication to stop the formation of new blood vessels.  Photodynamic therapy uses a light to activate an injected drug designed to destroy leaking vessels.