Do genetic factors influence glaucoma?

Is it genetic?

Scientists believe that genetics are a key factor in developing all major forms of glaucoma. People with a family history of a specific type of glaucoma are at higher risk of developing it. Different types of glaucoma have different inheritance patterns.

Primary open-angle glaucoma

Primary open-angle glaucoma (POAG) is the most common type of glaucoma. According to the National Eye Institute (NEI), 9 in 10 people with glaucoma have open-angle glaucoma. People with POAG may have glaucoma symptoms that develop slowly over time. However, in many cases, POAG often has no symptoms in its early stages.

POAG is hereditary. If members of a person’s immediate family have glaucoma, they are at higher risk of developing it themselves. Researchers have identified at least 16 genes that cause POAG to date.

Primary angle-closure glaucoma

Primary angle-closure glaucoma (PACG) refers to when the drainage angle in the eye is narrow, which reduces how easily fluid can escape the eye. People with PACG can have symptoms that come on suddenly or over time.

Scientists are still investigating the genetic causes of PACG. Some studies have identified several genes that may make people more likely to develop PACG.

Primary congenital glaucoma

Primary congenital glaucoma (PCG) is a rare condition. According to the National Eye Institute, 1 in 10,000 people in the United States is born with PCG. It is the most common form of glaucoma in infants under 3 years old.

People born with PCG have eyes that do not drain fluid properly. Parents of children born with PCG typically notice the signs right away. These include:

• cloudy eyes
• sensitivity to light
• extra tears
• larger-than-normal eyes

People are more at risk of being born with PCG if their parents:

• are related to each other by being second cousins or closer
• have first-degree relatives with PCG
• have certain genes
• have a family history of PCG, although this only accounts for 10% of PCG cases

Doctors can often use surgery to treat PCG. If an infant has surgery early enough, they do not usually have any permanent vision loss.

Early-onset glaucoma

If a person develops glaucoma before age 40 years, they have early-onset glaucoma. Glaucoma that develops during a person’s childhood or early adulthood is known as juvenile early-onset glaucoma. A person’s risk of early-onset glaucoma mainly depends on genetics.

People pass down different types of early-onset glaucoma in different patterns. Some people who carry genes that can cause early-onset glaucoma will not develop it, but they may still pass it on to their children.

Scientists have identified several genes that can cause early-onset glaucoma and continue research into finding more.

Exfoliation glaucoma

Exfoliation syndrome (XFS) causes extra material to build up inside a person’s eye. This blocks fluid from draining and raises fluid pressure, leading to exfoliation glaucoma (XFG).

Some scientists believe that genetics affects a person’s risk of developing XFG. For example, evidence notes that variants of the LOXL1 gene are associated with XFS. However, a 2017 article suggests that there were no significant genetic risk factors for XFS. They suggested that other environmental factors could raise a person’s risk of XFS, such as:

• higher coffee consumption
• lower dietary intake of folate
• extra ultraviolet (UV) light exposure from more time spent outside

Other possible causes and risk factors

Other factors that raise a person’s risk of glaucoma include:

• having diabetes
• being age 60 years or older
• having short-sightedness or long-sightedness
• having a certain ethnic background, as African American people are at higher risk of POAG

Glaucoma symptoms

Glaucoma does not initially cause any symptoms. Over time, people with glaucoma may slowly lose their peripheral vision and then start to experience vision loss.

Some forms of glaucoma, such as angle-closure glaucoma, can occasionally cause other, more sudden symptoms. These include:

• intense eye pain
• upset stomach, or nausea
• red eye
• blurry vision
• tenderness around a person’s eyes
• rings around lights in a person’s vision

If a person suddenly has any of these symptoms, they should seek urgent medical attention.

Diagnosis

Doctors check people for glaucoma as part of a series of tests called a dilated eye exam. This test allows the doctor to look at the optic nerve. They may also check the pressure within a person’s eye. There are typically no risks with a dilated eye exam, but some of the tests may feel uncomfortable. After the test, a person may need to wear sunglasses and avoid driving.

The Centers for Disease Control and Prevention (CDC) recommend that people have a dilated eye exam if they are at risk of glaucoma due to hereditary or other factors, or are over the age of 40 years.

Treatment options

To reduce the pressure in a person’s eye and help prevent permanent vision loss, doctors can treat glaucoma with:

• eye drops
• medication
• surgery or laser eye treatment, to help fluid drain out of a person’s eye

Prescription eye drops are the most common treatment for glaucoma. Doctors may prescribe people a combination of these treatments.

Summary

Anyone can develop glaucoma. However, people with a family history of glaucoma are often more likely to develop glaucoma themselves.

If left untreated, glaucoma can cause people to lose vision or go blind. Eye tests can detect the early stages of glaucoma. This allows doctors to treat people for it, which can help prevent the condition from progressing.