Age-related Macular Degeneration (AMD)

Age-related macular degeneration (AMD) is an optic disease (related to the eyes) that worsens with time. It is one of the most common causes of severe, abrupt permanent loss of vision in people over the age of 60 years. It occurs when the small center of the retina, known as the macula, wears down. This disease occurs with progressing age, which is why it is also called age-related macular degeneration. It does not always lead to blindness but might cause severe vision problems. One of the macular degeneration disorders named Stargardt disease affects young adults. Macular degeneration in children is called juvenile macular degeneration.

Age-related macular degeneration is more common in older adults. It is a common cause of severe vision loss in adults over 60 years. In addition, macular degeneration is correlated with genetic factors. So the occurrence of macular degeneration within the family increases the risk.

Smoking, high blood pressure or high cholesterol, obesity, consuming a lot of saturated fats, female gender, light eye color, and fair skin people could be the contributing factors as well.

Some common risk factors include;

• Age: It is most common in people over 60 years of age
• Family history and genetics: It is related to the hereditary component
• Race: It is found more commonly in Caucasians.
• Smoking
• Obesity
• Cardiovascular disease

The worldwide prevalence of AMD is 8.7 percent in individuals ages 45 to 85 years. The projected number of affected people is 196 million in 2020, increasing to 288 million in 2040 if the incidence remains constant.

There are two major types of macular degeneration

Dry form: In this type, yellow deposits called drusen are seen in the macula. Minute collections of drusen will not cause any changes in the vision. But as they get large in size and numerous, they might disturb the vision, or complete loss of vision can occur especially noticed while reading. As the condition worsens, the macula’s light-sensitive cells get thin and eventually die. In the atrophic form, there may be blind spots in the center observed while seeing. Further worsening may completely cause loss of vision.

Wet form: When certain blood vessels grow underneath the macula, then these blood vessels leak blood and fluid into the retina. Vision gets quite distorted, so the straight lines look wavy. There may be blind spots and loss of central vision. These blood vessels and the bleeding within eventually form a scar, resulting in permanent loss of central vision.

Some common signs and symptoms include:

• Vision becoming worse or less clear: Vision might become blurry, and it may be hard to read fine print or drive.
• Dark, blurry patches in the center of the vision
• Differences in color perception

Annual eye examinations are crucial in detecting the disease as early signs do not show any symptoms, and starting treatments at early stages is beneficial. During an eye examination, changes in the retina and macula are observed. Healthcare providers may perform one or more of these tests:

Visual field test: An Amsler grid is used which consists of straight lines with a large dot in the center. The healthcare provider may ask to identify lines or sections on the grid that look blurry, wavy, or broken. Too much distortion may indicate that they have AMD or the disease is worsening. This visual field test can be done at home to evaluate changes in vision.

Dilated eye exam: Eye drops dilate, or widen the pupils. Once the eyes are dilated, your healthcare provider uses a special lens to examine your eyes.

Fluorescence dye: A yellow dye called fluorescein is injected into a vein in the arm. A special camera tracks the dye as it travels through blood vessels in the eye. The images captured can reveal any abnormal leakage under the macula.

Optical coherence tomography (OCT): During this test, an imaging machine takes detailed images of the back of the eye, including the retina and macula. Optical coherence tomography is not an invasive or painful procedure. A person simply looks into the lens while the machine takes pictures.

Optical coherence tomography angiography (OCTA): This diagnostic tool uses laser light reflection (instead of fluorescein dye) and the OCT scanning device. It takes just a few seconds and produces 3D images of blood flow through the eye.

Some other related disorders are;

• Genetic macular disease
• Stargardt disease,
• Best disease,
• Pattern dystrophy,
• North Carolina macular dystrophy,
• Central serous chorioretinopathy.
• Myopic degeneration

Some of the treatment strategies are;

Anti-angiogenesis drugs: These medications - aflibercept (Eylea), bevacizumab (Avastin), pegaptanib (Macugen), and ranibizumab(Lucentis) - interrupt the production of blood vessels and leak from the vessels in the eye that caused wet macular degeneration. Most of the people who’ve taken these drugs got back some lost vision. This treatment is required multiple times.

Laser therapy: High-energy laser beams can destroy abnormal blood vessels growing in the affected eye.

Photodynamic laser therapy: A light-sensitive drug, verteporfin (Visudyne) is injected, which is absorbed by the abnormal blood vessels. Laser beams are exposed to the eye to activate the medication to damage those blood vessels.

Low vision aids: These are devices that have special lenses or electronic systems to make larger images of nearby things.

People hardly lose all of their vision from age-related macular degeneration. Central vision might deteriorate, but they’re still able to perform several routine daily activities. Usually, peripheral vision is still intact. The dry form of age-related macular degeneration takes on a more slow course, so vision is usually safe.

The wet form of macular degeneration is a prominent cause of permanent vision loss. If it’s in both eyes, it can immensely affect the quality of life. Wet macular degeneration requires repeated treatments, and vision testing is done regularly.

Following changes in your life habits will be helpful in preventing and controlling AMD;

• Quit smoking.
• Keep your blood pressure well maintained.
• Eat healthy food including leafy vegetables.
• Protect your eyes from bright sunlight by using sunglasses
• If you have a family history, do the test yourself with the Amsler grid to keep a check.
• Try consuming supplements of vitamins C and E, lutein, zeaxanthin, zinc, and copper as it reduces disease progression.  

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