Macular Degeneration: An Overview and Risk Factors

Age-related macular degeneration (AMD) is the leading cause of blindness in the developed world in people over 50 years old. It is estimated that among North Americans, 11 million currently have ”dry” AMD, and 1.5 million people have “wet” AMD. AMD is the deterioration of the macula, which is a small area in the center of the retina that allows us to see details. The retina, the structure of the back of the inner eye, is like a camera in that it records what we see. However, the retina is different from a general film, as it has one specific area that allows the picture to come out perfectly clear. That area is the center point of the retina which is called the macula.

Damage to the macula affects our detailed vision and reduces the clarity of objects that we look at directly. This is the vision we use to read, drive, see the television, and do detailed work such as threading a needle, sewing, or crafts.

It also reduces contrast sensitivity – our ability to see objects that are the same tone as their background – so identifying faces and seeing curbs and steps may be difficult. Our peripheral vision, the wide area that includes everything that we are not looking directly at, remains intact so individuals with age-related macular degeneration can see all around the room, for example.

Simulation of the effects of macular degeneration, with central visual field loss

Simulation of the effects of macular degeneration, with central visual field loss

Overview

Normal aging causes changes to the macula; however, it is still hypothesized that certain modifiable risk factors are associated with age-related macular degeneration (AMD). The development of this disorder is poorly understood but though to include a mix of genetic predisposition along with other risk factors.

As we age, long-term environmental exposures together produce an increased number of free radicals, which are unstable molecules. These free radicals then go on to damage the macula. This damage causes a decreased number of photoreceptors, special type of neurons in the retina, as well as deposits in the retina itself. This hypothesis leads medical professionals to believe that by reducing toxins, the risk of age-related macular degeneration can theoretically be reduced.

Controllable Risk Factors

  • Smoking: Current smokers have a two-to-three times higher risk for developing age-related macular degeneration than people have who never smoked. Smoking is thought to be the number one modifiable risk factor that can worsen the progression of AMD.
  • Obesity: Studies have shown that obesity increases the risk of developing AMD
  • Uncontrolled hypertension: Research by the National Eye Institute indicates that persons with hypertension are 1.5 times more likely to develop wet macular degeneration than persons without hypertension.
  • Diet low in leafy green vegetables and fish: The risk of AMD is known to be reduced by eating healthy food, including leafy green vegetables and fish
  • Sunlight: There is not strong evidence that blue wavelengths or ultraviolet rays can cause AMD. However, there are no adverse effects from wearing UV protective glasses so some studies have suggested UV protection

The Four Risk Factors We Can’t Control

  • Advanced age: Although AMD may occur earlier, studies indicate that people over age 60 are at greater risk than those in younger age groups. This risk increases more than three-fold in patients older than 75 years of age as compared to the group of patients between 65-74 years of age (Beaver Dam Eye Study)
  • Race: Whites are much more likely to lose vision from age-related macular degeneration than any other racial group
  • A gene variant that regulates inflammation: While not all types of macular degeneration are hereditary, certain genes have been strongly associated with a person’s risk of age-related macular degeneration, and genetic predisposition may account for half the cases of age-related macular degeneration in this country.
  • Family history: Studies indicate that your chances of developing age-related macular degeneration are three to four times higher if you have a parent, child, or sibling with macular degeneration.

More about Risk Factors and Actions to Take

To decrease your risk of developing age-related macular degeneration, or to decrease the rate of progression if you already have age-related macular degeneration, here are some actions you can take:

  • Don’t smoke – and if you do smoke, try to stop.
  • Do eat lots of dark green leafy vegetables. These vegetables – such as kale, spinach, and collards – contain lutein, a substance that neutralizes the free radicals that will otherwise cause damage to the macula. If you are taking Coumadin and can’t eat these vegetables because of the vitamin K in them, you can take a lutein supplement.
  • Do eat lots of omega-3 fatty acids, which are found in fish, fish oil, flaxseeds, and some nuts. Omega-3 fatty acids reduce inflammation.
  • Do control your blood pressure and cholesterol levels.
  • Do exercise regularly and keep your weight down.

Written by Lylas G. Mogk, M.D., Edited by Sefy Paulose, M.D. March, 2022

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