Wet macular degeneration

Wet macular degeneration

Definition:

 Wet macular degeneration is a chronic eye disease that causes vision loss in the center of your field of vision. Wet macular degeneration is generally caused by abnormal blood vessels that leak fluid or blood into the region of the macula (MAK-u-luh). The macula is in the center of the retina (the layer of tissue on the inside back wall of your eyeball).

Wet macular degeneration is one of two types of age-related macular degeneration. The other type — dry macular degeneration — is more common and less severe. Wet macular degeneration almost always begins as dry macular degeneration. It's not clear what causes wet macular degeneration.
Early detection and treatment of wet macular degeneration may help reduce vision loss and, in some instances, improve vision.

Symptoms:

Wet macular degeneration symptoms usually appear and progress rapidly. Symptoms may include:

• Visual distortions, such as straight lines appearing wavy or crooked, a doorway or street sign looking lopsided, or objects appearing smaller or farther away than they really are
• Decreased central vision
• Decreased intensity or brightness of colors
• Well-defined blurry spot or blind spot in your field of vision
• Abrupt onset
• Rapid worsening
• Hallucinations of geometric shapes, animals or people, in cases of advanced macular degeneration

When to see a doctor
See your eye doctor if:

• You notice changes in your central vision
• Your ability to see colors and fine detail becomes impaired

These changes may be the first indication of macular degeneration, particularly if you're older than age 50.

Causes:

 It's not clear what causes wet macular degeneration. The condition almost always develops in people who have had dry macular degeneration. But doctors can't predict who will develop wet macular degeneration, which is more severe and progresses more rapidly than dry macular degeneration.
Wet macular degeneration can develop in different ways:

• Vision loss caused by abnormal blood vessel growth. Wet macular degeneration may develop when abnormal new blood vessels grow from the choroid — the layer of blood vessels between the retina and the outer, firm coat of the eye, called the sclera — under and into the macular portion of the retina. This condition is called choroidal neovascularization.
  These abnormal vessels may leak fluid or blood between the choroid and macula. The fluid interferes with the retina's function and causes your central vision to blur. In addition, what you see when you look straight ahead becomes wavy or crooked, and blank spots block out part of your field of vision.
  
• Vision loss caused by fluid buildup in the back of the eye. Wet macular degeneration sometimes may develop when fluid leaks from the choroid and collects between the choroid and a thin cell layer, called the retinal pigment epithelium (RPE). This may cause retinal pigment epithelium detachment.
  The fluid beneath the RPE causes what looks like a blister or a bump under the macula.

 Treatments and drugs:


Wet macular degeneration can't be cured. If diagnosed early, treatment may help slow progress of wet macular degeneration and reduce the amount of vision lost.
Medications to stop growth of abnormal blood vessels
Medications may help stop growth of new blood vessels by blocking the effects of growth signals the body sends to generate new blood vessels. These drugs are considered the first-line treatment for all stages of wet macular degeneration.
Medications used to treat wet macular degeneration include:

• Bevacizumab (Avastin)
• Ranibizumab (Lucentis)
• Pegaptanib (Macugen)
• Aflibercept (Eylea)

Your doctor injects these medications directly into your eye. You may undergo repeat injections every four weeks to maintain the beneficial effect of the medication. In some instances, you may partially recover vision as the blood vessels shrink and the fluid under the retina absorbs, allowing retinal cells to regain some function.
Some of these medications may increase the risk of stroke.

Using light to activate an injected medication (photodynamic therapy)
Photodynamic therapy is used to treat abnormal blood vessels at the center of your macula.
In this procedure, your doctor injects a medication called verteporfin (Visudyne) into a vein in your arm, which travels to blood vessels in your eye. Your doctor shines a focused light from a special laser to the abnormal blood vessels in your eye. This activates the medication within the abnormal blood vessels. The medication then can cause the abnormal blood vessels in your eye to close, which stops the leakage.
Photodynamic therapy may improve the vision and reduce the rate of vision loss. You may need repeated treatments over time, as the treated blood vessels may reopen.
After photodynamic therapy, you'll need to avoid direct sunlight and intensely bright lights until the drug has cleared your body, which may take a few days.

Using a laser to destroy abnormal blood vessels (photocoagulation)
During laser therapy, your doctor uses a high-energy laser beam to destroy abnormal blood vessels under the macula. The procedure is used to prevent further damage to the macula and slow continued vision loss.
Laser therapy is used to treat wet macular degeneration only in certain situations. It generally isn't an option if you have abnormal blood vessels directly under the center of the macula. Also, the more damaged your macula is, the lower the likelihood of functional success. Because of these restrictions, few people who have wet macular degeneration are candidates for laser therapy.