Macular Degeneration: Symptoms, Causes, and Treatment

Nearly 20 million older Americans are losing their eyesight due to macular degeneration. Understanding this condition and its causes can help you lower your risk. Optometrist Jeff Anshel, OD, explains here the causes and what you can do to keep your eyes healthy…

What is macular degeneration?

The terms “macular degeneration” and “age-related macular degeneration (AMD) are often used interchangeably because the condition mainly affects people in their 50s and older. The macula, part of the retina at the back of the eye that is the central focal point of the light from which we form images, consists of structures called rods and cones, which are among the body’s most metabolically active cells. When light reaches those cells, a chemical reaction occurs to produce sight. Each time that reaction takes place, parts of the cells break off. Normally, those pieces of broken-up cells pass through a barrier at the back of the eye called the retinal pigment epithelium, which transports the waste material into the bloodstream for disposal. Then, healthy new rods and cones are generated.

After many decades of this process, the retinal pigment epithelium starts to lose its ability to transport the waste cells, and they start to accumulate in the macula. Those particles, known as drusen, begin to disrupt sight at the center of a person’s vision. Using the appropriate instrument, an optometrist or ophthalmologist can see drusen as little dots that appear to be embedded in the retina. This often is the first sign of macular degeneration.

Macular degeneration has two stages

The retinal pigment epithelium is not a one-way street. Besides transporting drusen out of the eye for disposal, it also carries blood and nutrients into the eye to support healthy eye function. Unfortunately, the drusen languishing in the macula block this incoming transport. A person at this stage is said to be suffering from dry AMD, which accounts for about 90% of cases.

After a while, the body senses that it needs to start getting nutrients into the eye, so it undertakes an immune response and releases a substance called vascular endothelial growth factor (VEGF). VEGF prompts the creation of new blood vessels at the back of the eye, but those new blood vessels are poorly constructed and weak. They frequently leak blood and other fluids into the eye. When a person has reached this more advanced stage of AMD, they’re said to have wet AMD.

Macular degeneration symptoms

AMD has no early warning signs. While AMD rarely causes total blindness, people who don’t get their eyes checked regularly may notice one day that they’ve begun to lose sight at the center of their vision. If you wonder what vision looks like with macular degeneration, imagine trying to look at your grandchild’s face and seeing just his/her ears, hair and chin but not his features.

While AMD eventually affects both eyes, it usually starts on just one side. When one eye is impaired, our brains will “tune out” the poorer seeing eye and just use the better eye, so many people in the early stages of AMD don’t realize they’re having trouble seeing out of one eye.

Macular degeneration treatment

There currently is no treatment for dry AMD, but there are treatments for the wet version. The patient’s eye may be injected regularly with anti-VEGF, which disrupts production of the protein that causes growth of troublesome blood vessels in the eye. Injections sound daunting, but it’s done after a numbing agent has been applied and with a very fine needle in the top of the eye where there are no pain receptors. Preventing blood-vessel growth reduces swelling in the eye, and that temporarily improves vision. There is no cure for AMD.

Anti-VEGF injections used to be administered every four to six weeks, but new medications require intervals of just three to four months.

People living with AMD should use blue-light–blocking lenses all the time to prevent further damage. Blue-blocking is a “treatment” in the lenses and can be used in both clear and sunglasses (but they often cast a yellowish tint to the lenses).

 AMD can be quite debilitating. Since we use our center vision for 90% of our function, patients have to give up driving and other important activities. Until the damage becomes too great, some patients can use a magnifying glass to blow up the image of what they’re trying to see so that more of it appears outside the center of vision where the deficit is.

Preventing macular degeneration

Some risk factors, including age and genetics, are not modifiable, but you have control over others…

• Smoking. According to the CDC, smokers have twice the risk for AMD. Smoking is known to affect blood flow, and the retina is extremely dependent on blood, with the arteries and veins at the back of the eye highly vulnerable to trauma caused by smoke.
• Blue light. You’ve probably heard that the light emitted by computer screens damages the eyes—that blue light is modest, and your body has a built-in blue-light blocker called the macular pigment. The blue light coming from the sun is much greater. Self-defense: Purchase a pair of high-quality sunglasses. They should be precision-crafted, optically ground lenses that provide UV and blue-light protection.
• Diet. Eat an eye-healthy diet. Two nutrients in particular—lutein and zeaxanthin—are crucial for the retina’s health. Aim for 20 mg of lutein and 4 mg of zeaxanthin daily. The best plant sources of lutein and zeaxanthin are kale and spinach. Eat them cooked, which helps separate the lutein and zeaxanthin from the chlorophyll. One-half cup of cooked spinach or kale yields about 11 mg of lutein. One egg yolk provides about 0.3 mg of lutein and zeaxanthin, which doesn’t sound like much but is beneficial because the substances are highly bioavailable in that form.Since most of us don’t get enough lutein and zeaxanthin in our diet, purchase a supplement that contains both from a reputable supplier. Read the ingredients, not just the claims on the label, to make sure you’re getting at least 20 mg of lutein and 4 mg of zeaxanthin.
• Eye exams. And of course, every year get a thorough eye examination from an eye-care professional.