PXE Awareness

Volume 18, Issue 3 November 2012

 

Age-Related Macular Degeneration

 

What is age-related macular degeneration (AMD)?

AMD is a chronic condition that causes central vision loss.  This central vision loss from AMD is caused by damage to the center of the retina, otherwise known as the macula.  There are 2 forms of AMD: dry and wet.

What is dry AMD?

Dry AMD occurs when cells underneath the macula break down and create deposits called drusen.  These drusen can make you lose some vision.  Dry AMD usually develops slowly over time with few symptoms until it reaches an advanced stage.

What is wet AMD?

Wet AMD occurs when certain proteins cause abnormal blood vessel growth in the back of the eye.  As the blood vessels grow, they can leak blood and fluid, which damage the macula – the part of the retina that lets you see color and detail.  This can cause central vision loss.

Who has AMD?

Wet AMD is a major cause of central vision loss in Americans aged 60 and older.  And, it is more common in women than men.  It is estimated that more than 13 million people in the United States have some form of AMD, and more than a million men and women are affected with the more serious form of wet AMD.  By the year 2020, the number of people with wet AMD is expected to grow to approximately 3 million.

What causes AMD?

The exact cause of AMD is not known.  But there are a number of risk factors that may play a role.  These include age (60 and older), family history, gender (more common in women), smoking, cardiovascular disease, obesity, low levels of nutrients, and race (more common in white people).

How do I know if I have wet AMD?

The earliest symptom of wet AMD is vision change.  If you notice straight lines appearing wavy or doorways seeming crooked, you should get an eye exam right away.  This distortion may be an early sign of wet AMD.  Today, retina specialists have treatments that can prevent vision loss from getting worse, or even treatments that might help you get some of your vision back.  But early diagnosis is critical.  If you think you have symptoms of wet AMD, visit your eye doctor immediately.

Will AMD lead to blindness?

AMD affects your central vision only, not your peripheral – or side – vision.  So if your vision loss is only from AMD, you will not go completely blind.  You will be able to see out of the corner of your eye.  Talk to your eye doctor.

I have had dry AMD for years. Does this mean I’m going to get wet AMD too?

Only 1 in 10 people with dry AMD will get wet AMD.  However, wet AMD is a major cause of central vision loss in adults.  So if you have dry AMD, it is very important to use an Amsler grid daily (to check for vision changes that may occur) and to make regular visits to your eye doctor.

How can I treat dry AMD?

Currently, there is no proven treatment or cure for dry AMD.  That’s why it’s important to monitor your vision carefully, because dry AMD can get worse or even progress to wet AMD.

 How can I treat wet AMD?

In the past, there wasn’t much you could do to keep from losing vision to wet AMD.  But today there are several effective ways to treat this chronic condition.  Options include injections given into the eye, hot laser treatment, and photodynamic therapy (PDT).

How long will I need to treat my wet AMD?

AMD is a chronic condition.  Most people need to treat it long-term.  For best results, your eye doctor will develop a treatment schedule that is right for you.

If I am treating wet AMD in 1 eye, am I still at risk of developing wet AMD in the other eye?

Yes.  Treatments for wet AMD in the affected eye will not prevent wet AMD from developing in the unaffected eye.  Wet AMD can occur in 1 eye or in both.  If you have wet AMD in 1 eye, it’s important to carefully monitor the other eye.  That’s because there’s a 50% chance you will develop AMD in your other eye within 5 years.  Therefore, early detection can give you the best chance for success in treating wet AMD.

 What can I do to prevent the progression of AMD?

Currently, there is no way to prevent AMD.  However, studies have shown that a daily supplement including vitamins such as A, C, and E, as well as beta-carotene, zinc, and copper, may reduce some risks of developing advanced AMD in some patients.  Remember to talk to your eye doctor before taking any supplements.

Asking Questions is important!

To understand your condition and to be sure you get the treatment that’s best for you, you need to ask questions.  Your eye doctor is your partner for better vision.  Working together gives you the best chance to stay on top of AMD.

AMD Glossary

Acuity Test: Use of an eye chart to measure accuracy of reading and perception.

Amsler Grid: A grid used for checking distortion in the vision and central vision defects.

Antiangiogensis: Refers to a substance that prevents the development of new blood vessels.

Antioxidants: Substances produced by the body that counteract the effects of free radicals.  Present in dark green, leafy vegetables such as spinach and kale, and may also be acquired through supplements.

Bilateral: Referring to both eyes.

Central Visual Field: The area of objects seen in the direct line of vision without moving the head or eyes.

Choroid: The layer of the eye behind the retina.  This layer is filled with blood vessels that nourish the retina.

Clinical Testing (or trial): Direct observation of a living patient to answer specific questions about vaccines, therapies, or new methods.  The 4 phases of a clinical trial are Phase I: determination of safety and side effects on 20 to 80 people; Phase II: determination of effectiveness and safety on 200 to 300 people; Phase III: confirmation of results on 1000 to 3000 people; and Phase IV: studies done after FDA approval and public use.

Cornea: The clear front surface of the eye.

Drusen: Tiny yellow or white protein-and-fat deposits in the retina.

Dry AMD: The most common form of age-related macular degeneration, where drusen form on the retina.

Edema: An abnormal or excess accumulation of fluid in a tissue.

FDA: Abbreviation for the United States Food and Drug Administration.  Responsible for approving and regulating treatments, procedures, and pharmaceuticals.

Fluorescein Angiography: A test to examine blood vessels in the retina, choroid, and iris.  A special dye is injected into a vein in the arm, and pictures are taken as the dye passes through blood vessels in the eye.

Intravitreal Injection: The administration of a substance (such as a drug) with a needle into the vitreous fluid of the eyeball between the lens and the retina.

Iris: The colored diaphragm in the anterior chamber of the eyeball that contracts and expands to adjust for light intensity.

Laser Photocoagulation: An outpatient treatment in which blood vessels are cauterized by the heat from a fine-point laser beam.

Legal blindness in the United States: 1) Visual acuity of 20/200 or worse with the best correction possible (20/200 means that a person must be 20 feet from an eye chart to see what a person with normal vision can see at 200 feet) or 2) Visual field restricted to 20 degrees diameter or less (tunnel vision) in the better eye.  NOTE: These criteria are used to determine eligibility for government disability benefits and do not necessarily indicate a person’s ability to function.

Lens: The transparent part of the eye that focuses light rays onto the retina.

Low Vision: Visual loss that cannot be corrected with eyeglasses or contact lenses, and that interferes with daily living activities.

Low-Vision Devices: Equipment designed to allow improved vision, usually by magnification.

Macula: The small, sensitive area of the central retina that provides vision for detailed work and reading.

Neovascularization: Growth of new, fragile blood vessels that may leak beneath the retina.

Ophthalmologist: A medical doctor who specializes in disease and surgery of the eye.

Optical Coherence Tomography (OCT): A diagnostic method that uses an optical device to generate a cross-section image of the retinal layers, allowing for measurement of tissue thickness.

Optician: A technically trained specialist who sells glasses.

Optometrist: A doctor who examines vision in order to provide corrective glasses and contact lenses.  May also diagnose eye disease, and in some states, can treat disease.  Some optometrists specialize in low vision and are your best source for specialized devices.

Peripheral Vision: Side vision; ability to see objects and movement outside of the direct line of vision.

Photodynamic Therapy (PDT): The process of blood vessel coagulation in the retina through activation of a light-sensitive drug injected into the system.

Pupil: The opening in the center of the iris that appears as a black dot, through which light enters the eye.

Retina: The light-sensitive layer of tissue that lines the back of the eyeball.  Sends visual messages through the optic nerve to the brain.

Retina Specialist: An ophthalmologist who has completed additional training with parts of the eye, like the retina and other areas in the back of the eye.  Retina specialists commonly treat people with diabetic eye disease and macular degeneration.

Scotoma: An area of partial or complete loss of vision surrounded by an area of normal vision.

Snellen Eye Chart: The standard tool for the measurement of visual acuity, displaying letters of progressively smaller size.

20/20 Vision: The ability to correctly perceive an object or letter of a designated size from a distance of 20 feet; normal visual acuity.

Vascular Endothelial Growth Factor (VEGF): A protein that stimulates new blood vessel growth.

Visual Acuity: Level of clarity, distinction, or sharpness.

Visually Impaired: People who have some difficulty seeing with 1 or 2 eyes, even when wearing glasses.

Wet AMD: Age-related macular degeneration that is caused by abnormal blood vessel growth in the back of the eye.  As these blood vessels grow, they can leak blood or fluid, which damage the macula.