Is Glaucoma Genetic?

Is Glaucoma Genetic?

Glaucoma is an eye disease characterized by damage to the optic nerve, which carries signals from your eyes to your brain. Without a healthy optic nerve, well, it’s kind of difficult to see. The problem with glaucoma (other than the fact that it causes irreversible vision loss) is that there are rarely any warning signs. With around 3 million Americans living with glaucoma, it’s possible that you know at least one person with this eye condition. In fact, you may even be related to such a person. This then leads to the pertinent question – is glaucoma genetic?

What Causes Glaucoma?

There are several different types of glaucoma, which can be broadly categorized into two types – open angle and closed angle glaucoma. The anterior angle of the eye is a structure created where the colored iris meets the transparent cornea. A fluid called aqueous humor drains out from the eye through this channel, all the while continuously being produced at the same time. The balance of aqueous humor production and drainage dictates the internal pressure of the eyeball, known as intraocular pressure.

The majority of glaucoma cases are caused by an elevation in intraocular pressure, which ends up damaging the optic nerve. In open angle glaucoma, the anterior angle is still wide, but for some reason is unable to drain fluid well. In closed angle glaucoma, the space between the iris and cornea is so narrowed that fluid is unable to get out. However, some individuals develop glaucoma even when their intraocular pressure is within normal range, adding more complexity to an already complex disease.

Although doctors understand (for the most part) about how intraocular pressure plays a crucial role in the development of glaucoma, it’s not always clear why someone’s eye pressure increases, particularly when the anterior angle is still open. Some examples of known causes include:

  • Using corticosteroid medications
  • Trauma and eye injury
  • Inflammation inside the eye

Glaucoma may also be congenital, meaning a baby can be born with the condition. This may be due to malformation of anatomical structures in the eye during fetal development.

Is Glaucoma Genetic?

Over the last few decades, researchers have learned more about the role genetics play in the development of glaucoma. Over a hundred genes have been identified in relation to glaucoma and raised intraocular pressure, though there’s still a lot more work to be done. Also, given the variety of glaucoma subtypes, the genetics and patterns of inheritance can differ from one to the other.

Having a family member with glaucoma is a well-established risk factor for developing it yourself, especially if it’s an immediate family member, such as a parent or sibling. The statistics tell us that roughly half of all people with glaucoma have a family history of this condition. If you have a first-degree family member with primary open angle glaucoma, your risk of developing this condition is increased 9-fold; if you have a sibling with primary closed angle glaucoma, your risk may be increased by over 13 times (that’s a lot).

It’s important to note that even if your family medical history is pristine and boasts only of full and perfect health, it is still possible to develop glaucoma. Remember, 50% of people with glaucoma have a family history – that means the other 50% have no known family members with glaucoma.

Increase Your Glaucoma Awareness

Given that most cases of glaucoma begin silently – earning this disease the nickname of the sneak thief of sight – it pays to be vigilant about your eye health. Intraocular pressure increases slowly in open angle glaucoma, offering no clues or symptoms in the early to moderate stages. Vision loss is painless and usually begins in the periphery of your sight, where you’re least attentive to subtle changes. Once you become aware of your visual field being more restricted than it used to be, the vision loss is already significant. At this point in time, there is no known treatment that can reverse damage to the optic nerve and restore lost sight.

The good news is that vision loss tends to progress slowly in glaucoma, giving you a better chance at initiating treatment early. In most cases, glaucoma is treated with pressure-lowering eye drops, which are instilled one to three times a day, long-term. Other options for managing glaucoma include various forms of surgery or laser treatment.

The exception is situations of closed angle glaucoma, which can present with acute and somewhat alarming symptoms. Blurred vision, haloes around lights, a red, painful eye, and even nausea and vomiting, should alert you that something is not right. Vision loss can be rapid and profound in these cases, so a visit to emergency is a good idea.

Nothing can definitively prevent you from developing glaucoma (especially if you have those pesky genes working against you). However, you can catch it early and minimize or avoid vision loss by attending regular eye tests with your eye-care professional, whether optometrist or ophthalmologist. Depending on your risk factors, your doctor might recommend you pay them a visit every year or every couple of years. A glaucoma examination may include:

  • Visualizing your optic nerves using specialized tools such as a fundus lens and slit lamp or ophthalmoscope
  • Performing visual field testing to measure the sensitivity and extent of your peripheral vision
  • Measuring your intraocular pressures with a technique called tonometry
  • Taking retinal photos to record the appearance of your optic nerve
  • Running a specialized scan known as optical coherence tomography to gain greater detail about your retina and optic nerves

In addition to a family history, it’s important to be aware of other risk factors that can increase your likelihood of developing glaucoma. Understanding your risk profile helps your eyecare practitioner to manage you appropriately. Other risk factors include:

  • Older age, especially after 60 years
  • Ethnicity
    • African Americans are at higher risk of primary open angle glaucoma
    • Japanese are at higher risk of low-tension glaucoma
    • Southeast Asians and Native Alaskans are at higher risk of closed angle glaucoma
  • Certain medical conditions, including migraines, diabetes, sleep apnea, and hypertension
  • A history of certain eye conditions, including eye injuries or inflammatory eye diseases
  • Being near-sighted (myopic) or far-sighted (hyperopic)

The take home message today is not really whether glaucoma is hereditary or not, but that regular and routine eye checkups are important. With a disease called the sneak thief of sight lurking out there, you don’t want to be taking any chances with your vision.