Macular Degeneration

Macular degeneration, also referred to as age-related macular degeneration or senile macular degeneration is a common eye disease.  Macular degeneration is associated with aging.  It can destroy sharp central vision.  Early detection is the best defense against visual loss from macular degeneration.  Some forms of macular degeneration may be treated with medications, laser therapy, or photodynamic therapy.  Low vision aids may help improve the quality of life for people that experience vision loss.

The retina is located at the back of your eye.  The retina is a thin tissue layer that contains millions of nerve cells.  The nerve cells are sensitive to light.  A main purpose of your eye is to focus light on the retina.  The choroid is the lining underneath the retina.  The choroid contains blood vessels that supply your retina with blood and oxygen to keep it healthy.  

Cones and rods are specialized receptor cells in the retina.  Cones are specialized for color vision and detailed vision, such as for reading or identifying distant objects.  Cones work best with bright light.  The greatest concentration of cones is found in the macula and fovea at the center of the retina.  The macula is the center of visual attention.  The fovea is the site of visual acuity or best visual sharpness.  

 

Rods  are located throughout the rest of the retina.  Your eyes contain more rods than cones.  Rods work best in low light.  Rods perceive blacks, whites, and grays, but not colors.  They detect general shapes.  Rods are used for night vision and peripheral vision.  High concentrations of rods at the outer portions of your retina act as motion detectors in your peripheral or side vision.  The receptor cells in the retina send nerve messages about what you see the occipital cortex in the brain, where you process and perceive vision.

The exact cause of macular degeneration is unknown.  It most frequently occurs with increasing age and tends to run in families.  Macular degeneration is more common in Caucasians, people with light colored eyes, and people that smoke cigarettes.  Research suggests that obesity and nutritional intake may be linked to macular degeneration.

 

Macular degeneration begins with the partial breakdown of the structure which helps regulate the retinal metabolism.  The retina thins and dry macular degeneration results when the light sensitive cells in the macula break down, causing gradual central vision loss.  Dry macular degeneration is the most common type of macular degeneration.  In some individuals, tiny dot-like deposits, known as drusen, slowly accumulate beneath the macula.  While these deposits usually do not cause visual loss directly, they indicate that a person is at risk for developing further problems with the macula.  Dry macular degeneration may or may not turn into wet macular degeneration.
 
Wet macular degeneration, also referred to as advanced macular degeneration, is another type of macular degeneration.  It occurs when abnormal blood vessels grow underneath of the macula.  These new blood vessels are fragile.  They may break and leak blood.  The blood builds up and a mound of scar tissue develops that raises the macula from its normal position.  Wet macular degeneration can cause severe rapid central vision loss.  

Dry macular degeneration tends to develop slowly.  It is painless, but progressively gets worse.  It causes gradual changes in your vision.  Objects may look washed out or you may have difficulty seeing fine details.  You may have a blurred area in the center of your vision.  As the condition progresses, the blurred area may become larger and darker.  You may need more light than you did before to read or perform other tasks.  You may have difficulty seeing a person’s face well enough to recognize it until they are close to you.
 
Loss of central vision may occur rapidly with wet macular degeneration.  A major symptom is distorted vision.  Fine straight lines may appear wavy or crooked.  It may be difficult to read or watch television.  Your central vision may appear dim or absent.  Wet macular degeneration can cause severe central vision loss, but the peripheral (side) vision usually remains intact.

You should contact your doctor if you experience any changes in your vision.  Macular degeneration can be detected during a comprehensive eye examination. 

 

An Amsler grid is used to screen for macular degeneration.  You will be instructed to stare at a black dot in the center of the grid.  The grid has a checked pattern of straight lines.  You will state if the lines on the grid look straight, wavy, or crooked.  Your doctor may provide you with an Amsler grid for daily or weekly home screening.  You should immediately report any changes that you see on the Amsler grid to your doctor.

 

Imaging tests may be used to photograph the blood supply in your retina.  There are several types of imaging tests including fluorescein angiogram, indocyanine green (ICG) angiography, and optical coherence tomography (OCT).

 

Fluorescein angiography is a specialized type of photographic eye test that is used to detect blood vessel problems in the retina and choroid.  The test uses an injected dye and a special camera to take photos of vascular structures.

 

ICG angiography is a high-speed photographic eye test that is used to detect blood circulation problems in the choroid.  ICG can be helpful for gathering in-depth information about bleeding in the back of the eye and eye functioning when standard examination and testing alone cannot isolate the problem.  The test uses an injected dye and special cameras to take photos of the blood vessels.  ICG is used to diagnose certain eye conditions, such as macular degeneration, or to determine if laser treatment is possible. 

 

OCT is a new imaging technology that helps visualize blood vessels in the retina.  OCT takes cross-sectional pictures of the retina.  It is a fast, non-contact and non-invasive procedure.  OCT is used to help diagnose macular degeneration and to follow the course of treatment.

Early detection is the best defense against visual loss from macular degeneration.  There is no cure for macular degeneration, although treatments may slow the progression of the wet form.  There is no treatment for the dry form of macular degeneration.  Zinc supplements and other vitamin and mineral combinations may slow the progression of the disease.  Low vision aids may help improve the quality of life of people that experience vision loss. 

 

While scientific studies are not yet conclusive, researchers suggest that health and lifestyle changes may help reduce the risk of developing macular degeneration.  It may be helpful to attain and maintain a healthy weight, blood pressure, and cholesterol levels.  Multivitamins that contain anti-oxidants such as zinc, selenium, Vitamin C, Vitamin E, and Lutien may be helpful.  Also not yet proven, researchers suggest that it may be helpful to wear sunglasses with UV protection to block exposure to UV sunrays.
 
Some cases of wet macular degeneration may be treated with laser therapy, photodynamic therapy, or medications.  Laser surgery may be used to treat wet macular degeneration.  Laser treatments are usually more effective in the early stages of the disease.  Laser surgery uses high-energy light beams to destroy abnormal or leaking blood vessels. 

 

Photodynamic laser treatment (PDT) is a laser technique used to seal leaks at the center of the macula without damaging the central vision.  Photodynamic laser treatment (PDT) involves administering an IV medication before the laser treatment is performed, which super-sensitizes the leaking vessels to the laser beam.  This allows the use of a very low energy laser, which seals the leak but leaves the overlying retinal cells intact.  This treatment is very safe.  Only people with active leakage under the retina—the wet form—are candidates for this treatment.  The leaks must be very active and well defined (also known as “classic” leaks) and cannot exceed a certain size.
 
There are a few medications that are injected into the eye to treat wet macular degeneration.  They work to block the growth of new blood vessels that may leak and contribute to vision problems.  The injected medications may help slow the progression of wet macular degeneration. 

 

If you have experienced vision loss that interferes with your daily activities, ask your doctor about low vision services and devices that may help optimize the vision that you have.  Your doctor may refer you to a low vision specialist for low vision device training and education.  There are a multitude of low vision services and devices that may increase your independence, increase your activity level, and improve the quality of your life.

New drugs are being developed that will be more effective against wet Macular Degeneration either by injection or possibly in the form of eye drops.  There are some potential new treatments also developing for dry Macular Degeneration.  A tremendous amount of research is being done as this condition is becoming epidemic as we live longer.