Age-Related Macular Degeneration: Why your central vision is blurred?

Age-related macular degeneration (AMD) is a leading cause of vision loss among people aged 50 and older. AMD is an eye disease in which the eye macula deteriorates. The macula is the part of the retina responsible for central vision, allowing one to see fine details clearly and sharply; any disorder, like AMD, causes blurring of central vision. Over time, the blurred area grows larger, prompting the growth of blank spots in your central vision. The objects also appear to seem less bright than they used to be before AMD.

The Macula

The macula is an oval-shaped, yellow-colored spot near the center of the retina; this yellow color of the macula absorbs excess blue and ultraviolet light entering the eye, thus acting as a natural sunblock. The macula comprises millions of light-sensing cells that sense the light and provide sharp, central vision. The image formation mechanism begins with the retina turning the light into electrical signals, sending them to the brain through optic nerves, which are translated into the images we see. When the macula is damaged, the center of the view may appear blurry, distorted, or dark, as shown in the picture.

There are two types of macular degeneration: Dry macular degeneration and Wet macular degeneration-

1. Dry or atrophic macular degeneration

Most AMD exists in the dry form. This condition is caused by thinning of the macula tissues. Dry macular degeneration begins with the formation of tiny yellow or white pieces of fatty protein called drusen under the retina. This leads to thinning of the macula. People affected by dry macular degeneration may not observe any influence on their central vision because vision loss occurs gradually.

2. Wet or exudative macular degeneration

About 10 percent of people with macular degeneration have a wet form; the worsening of dry macular degeneration causes it and is relatively more disastrous to the central or detailed vision. Vision loss from this form is more noticeable and faster than dry macular degeneration. Wet macular degeneration occurs when abnormal blood vessels grow underneath the retina. These new blood vessels may leak fluid or blood, distorting the central vision.

What are the stages of AMD?

There are three stages of AMD, depending on the number and size of protein drusen.

1.    Early AMD

This stage is characterised by medium-sized drusen, about the width of an average human’s hair. People with early AMD typically do not have vision loss.

2.    Intermediate AMD

This stage is defined by relatively large drusen, pigment changes in the retina, or both. The stage can be identified only by an eye exam. Intermediate AMD may cause some vision loss, but symptoms are largely unnoticeable.

3.    Late AMD

A complete loss of central vision takes place here. There are two types of late AMD:

–     Dry AMD: there is a gradual breakdown of the macula tissues

–     Wet AMD: abnormal blood vessels grow underneath the retina

How could AMD be detected?

The early and intermediate stages of AMD usually start without symptoms. Only a dilated eye exam, a golden standard test, can detect your AMD. The ophthalmologist places medicated eye drops in your eyes to dilate your pupils and study them using a special magnifying lens. Sometimes, the test may be accompanied by fluorescent dye (Fluorescein angiogram). A harmless fluorescent dye is injected into your arm and travels to blood vessels in your eye, making it possible to see leaking blood vessels. It also confirms the presence of drusen protein and pigment cells, if any. However, the Amsler grid chart can detect any anomaly in central vision. Changes in your central vision may cause the lines in the grid to disappear or appear wavy, a sign of AMD. Dry macular degeneration is tested using the Amsler grid.

How to use the Amsler Grid chart?

Hold the grid 12 to 15 inches away from your face in good light. Cover one eye with a hand. Look directly at the center dot in the chart with the uncovered eye and keep looking at it. While looking directly at the center dot, note whether all grid lines are straight or if any areas are distorted, blurry, or dark. Repeat this procedure with the other eye. You must see your ophthalmologist if you see any wavy, blurred, or bleak pattern.

Who is more likely to be affected?

–     Age-related AMD – Age is a major risk factor for AMD. The disease is most likely to occur after age 60

–     Lifestyle-related AMD – Researchers have found links between AMD and some lifestyle choices, such as smoking, a non-balanced diet, not doing any exercises, etc.

–     Other diseases acting as precursors – High blood pressure and high cholesterol levels are also a cause of AMD.

–     Race – AMD is more common among Caucasians than among African-Americans or Hispanics/Latinos

–     Family history – People with a family history of AMD are at higher risk

Severity and persistence

AMD generally exhibits few or almost no symptoms in the early stages, so it is important to have your eyes examined regularly. Not everyone with early AMD will develop late AMD, which results in a complete loss of central vision.

Early AMD in one eye: Having early AMD in one eye means about 5 percent developing late AMD after 10 years

Early AMD in both eyes: Having early AMD in both eyes means about 14 percent developing late AMD after 10 years

Late AMD in one eye: Having late AMD in one eye only gives you a feeling of wellness and will not affect your vision much. With the other eye seeing clearly, you may still be able to drive, read, and see fine details. Having late AMD in one eye means you are at increased risk for late AMD in your other eye.

Late AMD in two eyes: Complete loss of central vision happens

How is AMD treated?

1.    Early AMD

Early AMD does not show symptoms or loss of vision; therefore, no treatment exists for early AMD. However, a dilated eye exam can be carried out to determine if your condition is advancing.

2.    Intermediate and late AMD

Researchers suggest that daily intake of certain high-dose vitamins and minerals can slow disease progression in people with intermediate AMD and those with late AMD in one eye. A diet that includes a combination of vitamin C, E, beta-carotene, lutein, zeaxanthin, omega-3 fatty acids, zinc, and copper can reduce the risk of late AMD by 25 percent.

3. Advanced AMD

Advanced AMD typically results in severe vision loss. However, eye care professionals can try different therapies to stop further vision loss.

–     Injections: Anti-VEGF drugs are directly injected into the eyes. This hinders the secretion of protein VEGF that promotes the growth of new abnormal blood vessels. Anti-VEGF injection therapy blocks this growth.

• Verteporfin drug: This drug is injected into the vein in your arm. This drug closes off the new blood vessels, slows their growth, and slows the rate of vision loss.

–     Laser surgery: This is the less common form of treatment and is rarely performed because laser treatment may also destroy some surrounding healthy tissues, also

The most important thing to cope with AMD is to stay positive. People who remain hopeful say they are better able to cope with AMD and vision loss. Stay engaged with family and friends. Seek a professional counselor or support group.