Some people are more likely than others to develop age-related macular degeneration (AMD). Risk factors for a disease are generally divided into modifiable factors — those you can control — and nonmodifiable ones. While you can’t completely control your chances of developing AMD, you can take steps to support your eye health and reduce your risk. If you’ve been diagnosed with AMD, there are treatment options that may be able to slow disease progression.

This article will cover common causes and risk factors for AMD. To learn more about your individual risk of AMD and what you can do to influence it, talk to an eye doctor.

What Is AMD and How Does It Develop?

AMD is an eye disease that can cause severe central vision loss. It most commonly affects people ages 50 and up. AMD affects the retina, the light-sensitive membrane located at the back of the eye. In people with AMD, the macula (center of the retina) becomes damaged. This affects your central vision — the ability to see what’s straight ahead, in detail.

There are two types of AMD — dry and wet. Dry AMD develops as the macula thins out over time with aging. Geographic atrophy (GA) is a severe form of dry AMD that occurs when the immune system mistakenly attacks the macula.

Wet AMD occurs when abnormal blood vessels leak fluid into the macula. Both dry and wet AMD cause visual impairment and can significantly affect your quality of life.

Causes of AMD

Ophthalmologists (specialists in eye diseases) and researchers aren’t quite sure what exactly causes AMD. It may develop due to a combination of genetic and environmental factors. People living with certain health conditions are also at higher risk for AMD.

Genetics

The genes you inherit from your parents are responsible for controlling many characteristics about you, including your eye color, height, and even your risk for certain diseases. Researchers have found that genetic factors contribute to 7 out of 10 AMD cases. The American Academy of Ophthalmology also notes that more than 30 genes contribute to a person’s risk of developing AMD.

Scientists know that people with certain gene variations are more likely to develop AMD than those without. The HTRA1 gene gives instructions for making the HTRA1 enzyme. This protein helps break down larger proteins into smaller pieces. HTRA1 also blocks the effects of transforming growth factor (TGF)-beta. This protein plays an important role in controlling cell growth and cell movement and in the formation of new blood vessels.

Research shows that people with variations in HTRA1 are at a higher genetic risk of developing AMD. These variations typically prevent cells from starting the process of making HTRA1 enzymes.

According to MedlinePlus, the ARMS2 gene is located next to the HTRA1 gene. Researchers aren’t quite sure whether AMD is related to variations only in HTRA1 or ARMS2, or potentially in both genes.

It’s important to note that simply having a gene variant associated with AMD doesn’t necessarily mean you’re guaranteed to develop it. It only means you have a higher risk of potentially having AMD in the future.

Family History of AMD

If you have a family member who has AMD, you’re at a higher risk of developing the disease yourself. In fact, having a parent or sibling with AMD raises your risk up to 50 percent. Talk with your family members about their health — including any eye diseases like AMD. If eye disease runs in your family, talk to your eye doctor about screening to catch early signs and symptoms.

Cigarette Smoking

Cigarette smoking is a leading cause of AMD and vision loss. In fact, studies show that people who currently smoke have a four times higher risk of developing AMD compared to those who do not smoke. Smoking can also accelerate AMD development by up to 10 years. People who smoke who do develop AMD are less likely to respond to treatment and often have more aggressive disease.

Environmental factors like smoking also go hand in hand with genetics to raise the risk of AMD. People who have HTRA1 gene variations and who also smoke are 20 times as likely to develop AMD compared to those who have variations in the HTRA1 gene and don’t smoke.

You may have heard that cigarette smoke contains thousands of chemicals, many of which are known to cause cancer. Many of these toxic substances also negatively affect eye health. For example, tar from cigarette smoke may lead to drusen formation. Drusen are deposits made of fat and proteins beneath the retina that can be seen by eye doctors during exams. They’re often the first sign that you may be developing AMD.

Cigarette smoking also damages the delicate blood vessels that bring oxygen and nutrients to the retina. If the retina can’t get what it needs to survive, damage can result. Oxidative stress and free radicals damage the retina as well. Smoking limits how well antioxidants work to protect the eyes.

Luckily, cigarette smoking is a modifiable risk factor for AMD. Your eye doctor will likely encourage you to quit smoking if you currently smoke. Doing so not only supports your eye health but also your overall health.

Obesity

Doctors determine who is clinically overweight or obese by measuring body mass index (BMI), which is calculated based on the ratio between a person’s height and weight. A BMI of 30.0 and above is clinically referred to as obesity.

Studies show that people with obesity are more likely to develop AMD. High fat levels lead to inflammation throughout the body. As a result, the immune system attacks healthy tissues — including the eyes. A person with clinical obesity is more than twice as likely to develop AMD than someone with a lower BMI measurement.

High Blood Pressure

Blood pressure measures the amount of force that blood flow puts on your blood vessel walls. The higher your blood pressure is, the more likely it is to damage blood vessels and lead to health problems.

People with hypertension (high blood pressure) are at an increased risk of AMD. Researchers believe that abnormally high blood pressure levels can damage the delicate blood vessels within the retina. Narrowed blood vessels caused by high blood pressure let less blood through, which can also limit oxygen and nutrients to the eyes. This can cause progression to more severe AMD — like geographic atrophy or wet AMD.

Unhealthy Diet

People who eat foods high in lipids (saturated fats and cholesterol) are more likely to develop AMD. This is because excess fat from your diet and high cholesterol levels can lead to drusen formation.

Your blood glucose (sugar) levels also affect your eye health. Foods with a high glycemic index cause rapid increases in your blood sugar, which can damage the eye’s blood vessels and raise the risk of AMD. High-glycemic foods, such as sugary snacks, white bread, white rice, and potatoes, are characterized by being high in refined carbohydrates and sugar and low in fiber. Your doctor may encourage you to swap high-glycemic index foods for low-index options.

Antioxidants are compounds that help fight inflammation and free radicals to stop tissue damage. Dark green leafy vegetables, citrus fruits, and nuts are all excellent sources of antioxidants. People who don’t include plenty of these foods in their diet have a higher chance of developing AMD.

Age and Sex

The older you are, the more likely you are to develop AMD. Your risk of AMD increases after age 60. According to the BrightFocus Foundation, 1 in 3 adults over the age of 75 are living with AMD. This is because your eyes have a harder time replacing old and worn out cells as you get older.

According to BrightFocus, females have a higher risk of AMD than males. Some health experts believe this is because females tend to live longer, so they are more likely to experience the effects of aging.

Sun Exposure

Some studies suggest that sun exposure can damage the eyes and lead to AMD. Specifically, the sun releases ultraviolet (UV) light that may harm the retina’s light-sensitive cells. People with light-colored eyes are at a higher risk of sun damage and AMD. Be sure to protect your eyes by wearing sunglasses or a hat with a brim while outside during the day.

Talk With Others Who Understand

On myAMDteam — the social network for people with age-related macular degeneration and their loved ones — members come together to ask questions, give advice, and share their stories with those who understand.

Are you or a family member living with AMD? Do you have any risk factors for AMD? Share your experiences in a comment below or on your Activities page.