MACULAR DEGENERATION

What is macular degeneration?

Macular degeneration (MD) is primarily an age-related retinal condition which affects central vision. This means that people with macular degeneration can’t see things directly in front of them. This common age-related eye condition which mostly occurs in people over the age of 50. There are two types of macular degeneration — wet and dry. It affects one or both eyes with different levels of severity. 

How common is MD?

Almost 20 million U.S. adults have macular degeneration. In the U.S., macular degeneration is a leading cause of vision loss in people who are 60 and older. 

What are the risk factors for MD?

Some people can develop macular degeneration at younger ages because of several factors. Risk factors for getting MD are:

• Having a family history of macular degeneration.
• Being overweight. 
• Smoking.
• Hypertension (high blood pressure).
• Eating a diet high in saturated fats.
• Being white. (https://my.clevelandclinic.org/health/diseases/15246-macular-degeneration) 

What are the types of MD?

There are 2 main types of MD:

• Dry MD: About 80% of those with AMD have the dry form. Some theories suggest it could be due to genetic predisposition whereas others suggest tiny yellow protein deposits called drusen form under your macula. This results in light-sensitive cells in the macula to slowly break down, generally one eye at a time. It is believed that the age-related damage of an important support membrane under the retina contributes to dry age-related macular degeneration.
• Wet MD: Though this type is less common, it usually leads to more severe vision loss in patients than dry AMD. It is the most common cause of severe loss of vision. Wet AMD happens when abnormal blood vessels start to grow beneath the retina. They leak fluid and blood, hence the name wet AMD which can create a large blind spot in the center of the visual field. (https://www.hopkinsmedicine.org/health/conditions-and-diseases/agerelated-macular-degeneration-amd) 

What are the causes of MD?

No one knows exactly what causes dry macular degeneration. Research suggests that it may be a combination of genes and other factors, including smoking, obesity and diet.

The condition develops as the eye ages. Dry macular degeneration affects the macula. The macula is the area of the retina that's responsible for clear vision in the direct line of sight. Over time, tissue in the macula may thin and lose cells responsible for vision.

What are the symptoms of MD?

Early dry MD doesn`t usually cause symptoms. As condition progresses, person may notice: 

• Visual distortions, such as straight line seem bent.
• Reduced central vision in one or both eyes.
• The need for brighter light when reading or doing close-up work.
• Increased difficulty adapting to low light levels, such as when entering a dimly lit restaurant or theater.
• Increased blurriness of printed words.
• Difficulty recognizing faces.
• A well-defined blurry spot or blind spot in the field of vision.
• When dry MD progresses to become wet MD, there is sudden change in vision resulting in serious vision loss. (https://www.mayoclinic.org/diseases-conditions/dry-macular-degeneration/symptoms-causes/syc-20350375) 

How is MD diagnosed?

In addition to a complete medical history and eye exam, your eye doctor may do the following tests to diagnose age-related macular degeneration:

• Visual acuity test: This common eye chart test measures vision ability at various distances.
• Pupil dilation: The pupil is widened with eyedrops to allow a close-up examination of the eye’s retina.
• Amsler grid: Used to detect wet age-related macular degeneration, this test uses a checkerboard like grid to determine if the straight lines in the pattern appear wavy or missing to the patient. Both indications may signal the possibility of age-related macular degeneration. (https://www.hopkinsmedicine.org/health/conditions-and-diseases/agerelated-macular-degeneration-amd) 
• Optical coherence tomography (OCT): helps to take detailed images of the back of your eye, including your retina and macula. 
• Optical coherence tomography angiography (OCTA): uses laser light reflection (instead of fluorescein dye) and the OCT scanning device. It takes just a few moments and produces 3D images of blood flow through your eye.

Fluorescein angiography: Used to detect wet age-related macular degeneration, this diagnostic test involves a special dye injected into a vein in the arm. Pictures are then taken as the dye passes through the blood vessels in the retina, helping the doctor evaluate if the blood vessels are leaking and whether or not the leaking can be treated.

How is MD treated?

Currently, there is no cure for MD. However, supplements such as Vitamin C, E, Lutein, Zinc, Copper and Zeaxanthin can help slow down disease progression. Low-vision devices can be used to build visual skills, develop new ways to perform daily living activities and adjust to living with age-related macular degeneration. 

Anti-vascular endothelial growth factor (VEGF) injections remain the mainstay to treat wet MD. They block the production of VEGF, which is a protein that produces new blood vessels. E.g. Aflibercept (Eylea®), Ranibizumab (Lucentis®), Bevacizumab (Avastin®), Faricimab-svoa (VABYSMO®). (https://my.clevelandclinic.org/health/diseases/15246-macular-degeneration)