MACULAR DEGENERATION

Symptoms * Treatment * Prevention * Coping

WHAT IS MACULAR DEGENERATION?

Age-related macular degeneration ( AMD) affects the eyesight of over 13 million Americans.  In many cases, the onset of AMD drastically limits ones’ mobility and devastates one’s sense of independence and security.  It strikes painlessly, disrupting the central vision needed to read, write, drive and to watch T.V.

AMD most often affects persons in their late fifties or sixties.  An estimated 200,000 Americans develop a severe form of AMD each year, making it the leading cause of functional blindness in people 65 or older.  One-third of the population over age 75 is likely to develop AMD.

This photo represents the way a person’s vision can be affected by macular degeneration.

  

Presently, there is no known cure or lasting treatment for AMD and, until recently, it had been considered impossible to treat in any form.  However, new advances in eye research such as photodynamic therapy offer hope to those whose lives have been affected by this disease or in whom the disease is likely to develop.

Technically, AMD is a group of similar diseases that destabilize the macula, a tiny section of the retina in the back of the eye.  The retina is a paper thin tissue that receives images and converts them into electrical signals sent to the brain through the optic nerve.  The retina contains two forms of light-receiving cells called rods and cones.  The macula, which is about the size of a pinhead, is rich in cone cells which give us our color and central vision.  Rod cells help us to see at night.

There are two main types of macular degeneration – the “dry” type and the “wet” type.  In either case, the disease leaves peripheral vision intact and most of those afflicted retain some usuable sight.

The “dry” or atrophic form accounts for 9 out of 10 AMD cases.  It is usually slow to develop and does not cause total loss of central vision.  Dry AMd is characterized by a thinning or deterioration of tissue underneath the macula and a slow breakdown of the cone cells.

The “wet” or exudative form occurs in only 1 in 10 cases of A MD but it causes about 90 percent of the cases of sever visual loss.  In “wet” AMD, abnormal blood vessels develop rapidly under the retina and leak blood or fluid that damage the macula causing sever and sometimes sudden vision loss.  The wet form often results in the growth of dense scar tissue.

WHAT CAUSES AMD?

The exact cause of AMD is unknown but it is almost always age-related and the incidence is higher in women than in men.  Although it is not an inherited disease in the classic sense, AMD may be clustered in some families.  The condition is more prevalent among Caucasians and appears to be most common in people with blue or light-colored eyes.  Additional risk factors may include, among others, hypertension, smoking and excessive exposure to ultraviolet (UV) rays, especially from the sun.

AMD SYMPTOMS

Anyone over 50, especially those with a family history of AMD, should have their eyes examined regularly by their eye doctor and should use the Amsler grid at home.   Below is an Amsler Grid and what it might look like to someone with AMD.

 

Amsler Grid Test

Click on this link to download the Amsler grid and directions on how to use it properly.

AMD is usually painless.  The “dry” type can be very slow in forming, but the “wet” type is likely to develop quickly and may cause sudden visual loss or distortion.  In some cases, the disease develops in one eye but does not affect the other for many years.  Symptoms vary and may include:

  • A blurring of printed words
  • Gradual development of blind spots in the center of the field of vision
  • Difficulty in picking out details, near and far
  • Straight lines appearing to be wavy and shapes distorted
  • Dimmed color vision

An eye doctor can detect early signs of AMD through a regular eye examination which might include the use of an Amsler grid.  To a person with AMD, the straight lines of the grid may appear to be wavy.

CAN AMD BE TREATED?

Recent advances in eye research offer new hope to victims of AMD.  In a small percentage of people with wet AMD, laser photocoagulation therapy can be used to destroy abnormal blood vessels and to seal leaks, thereby retarding the progression of the disease.

The treatment is usually a painless outpatient procedure, but even if the treatment succeeds in slowing the rate of vision loss, the laser may leave permanent blind spot where it has been applied.  In effect, the individual may lose some sight in order to slow the disease and extend the use of the remaining central vision.  Nonetheless, recurrence of new vessels and leakage are common even after laser therapy.

The compound, verteporfin, slow or halts the wet (and most sever) form of AMD.  Verteporfin is a photosensitive dye used in a laser procedure called photodynamic therapy (PDT).  Injected intravenously, the dye travels to the retina where it is then activated by shining a low intensity laser onto the damaged area.  This causes a chemical reaction which destroys the abnormal vessels. PDT can retard visual deterioration in about half of those treated by clearly does not cure the disease.  The treatment must be repeated periodically.

Presently, no proven treatment exists for the dry form of AMD.  However, researchers have discovered that a healthy macula has two yellowish pigments – the antioxidants known as lutein and zeaxanthin – they may block harmful blue light from damaging the retina.  Studies suggest that nutritional supplements containing these antioxidants may slow degeneration.

The Food and Drug Administration (FDA) today approved Lucentis (ranibizumab injection) for the treatment of patients with neovascular (wet) age-related macular degeneration (AMD). Lucentis is the first treatment which, when dosed monthly, can maintain the vision of more than 90 percent of patients with this type of AMD. Lucentis is a new molecular entity (NME), meaning it contains an active substance that has never before been approved for marketing in any form in the United States .

"This approval is of great importance for the 155,000 Americans who are diagnosed each year with AMD, a common cause of severe and irreversible vision loss in older adults," said Dr. Andrew von Eschenbach, Acting Commissioner of Food and Drugs. "At a time when our elderly population is rapidly increasing, this product preserves quality of life for those affected by this disease, helping them to regain the ability to participate in everyday activities such as reading and driving."

CAN AMD BE PREVENTED?

No one knows how to prevent AMD but the following practices may help to delay the onset of the disease.

  • Maintain a proper diet including fruits & vegetables right in antioxidants, especially leafy green vegetables such as spinach and collard greens.
  • Wear sunglasses and brimmed hats to avoid excessive UV exposure
  • Don’t smoke since smoking reduces the protective antioxidants in the eye

COPING WITH VISION LOSS

Until a cure or lasting treatment fro AMD is found, patients should consult an eye doctor and a low vision specialist for advice about products and rehabilitation techniques to maximize remaining vision.  There are many resources services available to help cope with AMD.

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