Macular Degeneration

Macular degeneration, often called AMD or ARMD (age-related macular degeneration), is the leading cause of vision loss and blindness in Americans aged 65 and older. Because older people represent an increasingly larger percentage of the general population, vision loss associated with AMD is a growing problem.

AMD occurs with degeneration of the macula, which is the part of the retina responsible for the sharp, central vision needed to read or drive. Because the macula primarily is affected in AMD, central vision loss may occur.

Archives of Ophthalmology in 2004 estimated that 1.75 million U.S. residents now have significant symptoms associated with age-related macular degeneration, with that number expected to grow to almost 3 million by 2020.

Wet and Dry Forms of Macular Degeneration

Macular degeneration is diagnosed as either dry (non-neovascular) or wet (neovascular). Neovascular refers to growth of new blood vessels in an area, such as the macula, where they are not supposed to be. The dry form is more common than the wet, with about 85%-90% of AMD patients diagnosed with dry AMD. The wet form of the disease usually leads to more serious vision loss.

Dry Macular Degeneration (non-neovascular). Dry AMD is an early stage of the disease, and may result from the aging and thinning of macular tissues, depositing of pigment in the macula, or a combination of the two processes.

Yellowish spots (drusen) that form in the back of the eye or retina can be an early sign of "dry" macular degeneration.

Dry macular degeneration is diagnosed when yellowish spots known as drusen begin to accumulate from deposits or debris from deteriorating tissue primarily in the area of the macula. Gradual central vision loss may occur with dry macular degeneration but is not nearly as severe as symptoms associated with the wet form of AMD.

No FDA-approved treatments are available for the dry form of macular degeneration. A major National Eye Institute study (AREDS) has produced strong evidence that certain nutrients such as beta carotene (vitamin A) and vitamins C and E may help prevent or slow progression of dry macular degeneration.

The AREDS study indicates that taking high dose formulas of certain nutritional supplements can reduce risk of early stage AMD progression by 25%. Some eye doctors also recommend that dry AMD patients wear sunglasses with UV protection against potentially harmful effects of the sun.

Wet Macular Degeneration (neovascular).

"Wet" macular degeneration occurs with formation of abnormal blood vessels and leakage in the back of the eye (retina), affecting the macula where fine focusing occurs.

In about 10% of cases, dry AMD progresses to a more advanced and damaging form of the eye disease known as wet macular degeneration. With wet AMD, new blood vessels grow (neovascularization) beneath the retina and leak blood and fluid. This leakage causes permanent damage to light-sensitive retinal cells, which die off and create blind spots in central vision.

Neovascularization, the underlying process causing wet AMD and abnormal blood vessel growth, is the body's misguided way of attempting to create a new network of blood vessels to supply more nutrients and oxygen to the eye's retina. But the process instead creates scarring, leading to sometimes severe central vision loss.

Wet forms of macular degeneration are further classified into two general types:

• Classic. When blood vessel growth and scarring has very clear, delineated outlines observed beneath the retina, this type of wet AMD is known as classic choroidal neovascularization (CNV) usually associated with more severe vision loss.
  
• Occult. New blood vessel growth beneath the retina is not as pronounced and leakage is less evident in the occult CNV form of wet macular degeneration, which typically produces less severe vision lo

Risk Factors of Macular Degeneration

• Older age (over age 60) - Advancing age is the most important risk factor

• Family history - If your relatives have macular degeneration, you have a greater risk.

• Caucasian - Caucasians tend to get macular degeneration more often than other ethnic groups.

• Gender - Women have significantly higher rates of macular degeneration after 75 years of age.

• Smoking - Smokers have a 2-3 fold higher risk; former smokers have 40-80% higher risk.

• Obesity - A person with abdominal obesity is more likely to develop macular degeneration.

• Elevated cholesterol - Higher levels of cholesterol may increase the risk.

• Hypertension - Severe hypertension has been associated with macular degeneration.

Symptoms of Macular degeneration

Macular degeneration can cause different symptoms in different people.  Sometimes only one eye loses vision while the other eye continues to see well for many years.  The condition may be hardly noticeable in its early stages.  But when both eyes are affected, reading and close work can become difficult.  You may experience one or more of the following symptoms.

• A dark or empty area appears in the center of vision
• Colors look dim
• Words on a page look blurred
• Straight lines look distorted or wavy, especially towards the center of vision
• Rapid loss of central vision

Diagnosis of Macular Degeneration

Many people do not realize that they have a macula problem until blurred vision becomes obvious.  Your ophthalmologist can detect earlier stages of macular degeneration during a medical eye examination  that includes the following:

• Viewing the macula with an ophthalmoscope
• A simple vision test in which you look at a grid resembling graph paper (Amsler grid - sample Amsler Grid)
• A color vision test

Sometimes a special photograph, called a fluorescein angiogram, is taken to find abnormal blood vessels under the retina.  Fluorescent dye is injected into your arm and your eye is photographed as the dye passes through the blood vessels in the back of the eye.

Treatment of Macular Degeneration

Despite ongoing research, there is not yet a cure for the condition.  Nutritional supplements may slow macular degeneration.  Treatment of the more common "dry" form of macular degeneration focuses on helping a person find ways to cope with visual impairment.  Various low vision optical devices can help people to continue with many of their favorite activities.  These devices may include:

• Magnifying glasses
• Closed-circuit television
• Large-print reading materials
• Talking or computerized devices

A wide range of support services, rehabilitation programs and devices are available to help people with macular degeneration to maintain a satisfying lifestyle.

People with "wet" macular degeneration can also benefit from low-vision optical devices.  But "wet" macular degeneration can usually be treated in its early stages with laser surgery.

Laser photocoagulation is used to destroy the abnormal blood vessels under the retina.  The focused beam of light seals the leaking blood vessels that damage the macula.  Although this procedure cannot cure macular degeneration, it can slow the rate of vision loss.  Laser photocoagulation can leave a small, permanently dark "blind spot" at the point of laser contact, but the procedure can preserve more sight overall.  Photo-Dynamic Therapy (with Visudyne) and Lucentis are also two new approaches to preserving sight. 

Treatments:

:: PDT
:: Lusentis

How Can You Protect Your Sight rom Macular Degeneration?

• Visit your eye care professional regularly.
• Monitor your vision daily with an Amsler grid.
• Take a multivitamin with zinc.
• Incorporate dark leafy vegetables into your diet.
• Always protect your eyes with sunglasses that have UV protection.
• Quit smoking.
• Exercise regularly.
• Be an avid learner.