According to a 2016 Johns Hopkins University School of Medicine survey “Public Attitudes about Eye and Vision Health”, published in JAMA Ophthalmology, nearly 50 percent of the 2,044 survey respondents, representing all U.S. ethnic and racial groups, selected loss of vision as the worst possible health outcome.
In the United States, the most common causes of blindness among people over age 50 years are age-related macular degeneration, glaucoma, cataract and diabetic retinopathy. Here are five things to know about age-related macular degeneration (AMD), its effects and how it is commonly treated.
1. AMD occurs when a particular portion of the retina deteriorates.
Age-related macular degeneration is characterized by the loss of central vision. Lining the back of the eye, the retina is an important part of the vision pathway responsible for receiving light taken in to the eye. The retina produces an image, transforms the image into a signal and transmits the signal to the optic nerve. The optic nerve then sends the signal directly to the brain, which generates sight.
Within the central portion of the retina is the macula, which is crucial to processing clear, straight-ahead vision. Located in the macula are photoreceptors, light-sensing nerve cells necessary for detailed central vision. In cases of AMD, the macula is damaged, causing central sight to appear wavy or blurred. It may even progress to a blind spot in the central vision.
2. AMD manifests in two forms.
The vast majority of people with AMD are diagnosed with “dry” AMD. Dry AMD occurs when the retina’s waste products accumulate, causing fat and protein deposits called drusen to grow beneath the retina. When drusen grow too large, they can cut off the retina’s flow of nutrients, killing the photoreceptors and causing vision loss. Dry AMD tends to worsen slowly over time.
The less common form of the disease is “wet” AMD. This version tends to progress more rapidly, and vision loss is usually more severe. Wet AMD occurs when fragile blood vessels grow beneath and eventually into the retina, where they can break, leaking blood and other fluids into the eye. The leaks cause the light-sensing cells in the retina to die, and may also cause scarring, leading to a severe form of vision loss.
3. Over 10 million people in the U.S. live with AMD.
As many as 11 million Americans live with some degree of macular degeneration. Within the next three decades, scientists anticipate that this number could double to almost 22 million. Worldwide, AMD is estimated to affect 196 million people. The global cost of AMD-associated visual impairment is an astounding $343 billion.
4. A person’s risk of developing AMD is tied to age, race, lifestyle habits, and genetics.
There are some risk factors for macular degeneration which can’t be controlled. For example, a person’s age is the biggest factor in the development of AMD. Though it can occur earlier, people over 60 years old have a higher risk of the disease.
Some people are also genetically prone to developing macular degeneration. Individuals who are Caucasian and those with a family history of the disease are more likely to contract it. Other risk factors associated with macular degeneration that can’t be controlled include being far-sighted, having light-colored irises, and having high levels of C-reactive protein in the body.
There are some risk factors that can be controlled, including a person’s lifestyle choices. Leading a healthy life can help prevent the development of high blood pressure and cardiovascular disease, and can prevent a person from becoming overweight. Each of these factors contributes to the likelihood that AMD will occur.
People should also take care to use proper eye protection in the sun. Unprotected exposure to the sun’s UVA light can contribute to the development of the disease.
While there is still research to be done on the topic, scientists recently published research indicating that the blue light emitted by digital devices is linked to AMD. Experts recommend limiting screen time as much as possible, not looking at smartphones or tablets in dark rooms, and wearing blue light-filtering eye protection both indoors and outside.
5. The effects of AMD are not reversible, but doctors can prescribe treatment to slow the disease in some cases.
Unfortunately, science has yet to find a cure for macular degeneration. However, a number of treatments can help slow the effects of the disease.
For mild cases of AMD, a doctor may do no more than prescribe a vitamin regimen to prevent further decline of a patient’s eyesight. Treatments for more advanced cases of macular degeneration may include various forms of laser therapy, injections of anti-angiogenic drugs into a patient’s eye, retinal translocation, and submacular surgery.
Doctors may also prescribe the use of certain low-vision aids to improve patient sight after serious AMD-related vision loss has already occurred. Only a licensed physician is able to determine the best course of action for an AMD patient based on his or her individual circumstances.