Glaucoma is a group of eye conditions that result in damage to the optic nerve, which is the nerve responsible for transmitting visual information from the eye to the brain. This damage can lead to vision loss, and if left untreated, can result in blindness.
One of the most common forms of glaucoma is called primary open-angle glaucoma (POAG), which is caused by an increase in pressure inside the eye, known as intraocular pressure (IOP). The increase in pressure can damage the optic nerve, leading to vision loss over time.
Another form of glaucoma is called angle-closure glaucoma (ACG), which occurs when the angle between the iris and the cornea, which normally allows fluid to flow out of the eye, becomes blocked. When this happens, the fluid in the eye is unable to drain properly, resulting in a rapid increase in intraocular pressure. This type of glaucoma can cause severe eye pain, headache, nausea and vomiting, and it’s considered a medical emergency as it can cause vision loss and blindness within hours if not treated immediately.
There are also different forms of Glaucoma like Normal-tension Glaucoma, Secondary Glaucoma, Congenital Glaucoma, Pigmentary Glaucoma, and others.
Glaucoma is a leading cause of blindness worldwide, and there is no cure for it. However, with early detection and treatment, it is possible to slow or even halt the progression of the disease and preserve vision. Treatment options include medications, laser therapy, and surgery. Regular eye exams with an ophthalmologist are important to catch glaucoma early and prevent vision loss.
What causes glaucoma?
The exact cause of most forms of glaucoma is not well understood, but several factors are thought to contribute to the development of the condition.
- Increased intraocular pressure (IOP): One of the main risk factors for glaucoma is increased intraocular pressure (IOP). When the eye’s aqueous humor, the fluid that nourishes the eye, cannot drain properly, it can build up and cause an increase in pressure inside the eye, which can damage the optic nerve.
- Age: Glaucoma is more common in older adults and the risk of developing glaucoma increases as you get older.
- Family history: A family history of glaucoma increases your risk of developing the condition.
- Ethnicity: Some ethnic groups have a higher risk of developing glaucomas, such as African Americans and people of African descent, are at a greater risk of developing the condition than other ethnic groups.
- Medical conditions: People with certain medical conditions, such as diabetes, high blood pressure, and heart disease, are at a higher risk of developing glaucoma.
- Eye injuries: Eye injuries can cause damage to the eye’s drainage canals, which can lead to an increase in intraocular pressure and a higher risk of developing glaucoma.
- Other eye conditions: other eye conditions such as cataracts, retinal diseases, and uveitis (inflammation inside the eye) increase the risk of glaucoma.
- Use of certain medications: Some medications, such as corticosteroids and certain antidepressants, can increase the risk of developing glaucoma.
Symptoms of glaucoma
The early stages of glaucoma often have no symptoms, which is why regular eye exams with an ophthalmologist are important to detect the condition early and prevent vision loss. However, as the condition progresses, it can cause the following symptoms:
- Gradual loss of peripheral vision: Glaucoma can cause damage to the optic nerve, which can result in a gradual loss of peripheral vision. This is often the first sign of glaucoma, and it can go unnoticed until the disease is in an advanced stage.
- Tunnel vision: In advanced stages of glaucoma, peripheral vision loss can progress and cause a sensation of seeing through a tunnel.
- Blurred vision: Some people with glaucoma may experience blurred vision.
- Halos around lights: Some people with glaucoma may see halos around lights, particularly at night.
- Red eyes: In angle-closure glaucoma, it can cause red eyes, eye pain and discomfort, nausea, and vomiting.
There are several different types of glaucoma, each with its own characteristics and causes. Here are some of the most common types:
- Primary open-angle glaucoma (POAG): The most common type of glaucoma, POAG is characterized by a gradual increase in intraocular pressure (IOP) and damage to the optic nerve. The cause of POAG is not well understood, but it is believed to be related to age-related dysfunction of the eye’s drainage system.
- Angle-closure glaucoma (ACG): Also known as acute or chronic angle-closure glaucoma, this type of glaucoma occurs when the angle between the iris and the cornea becomes blocked, preventing the proper drainage of the aqueous humor and leading to a rapid increase in intraocular pressure. This type can cause severe eye pain, headache, nausea, and vomiting and is a medical emergency.
- Normal tension glaucoma (NTG): This type of glaucoma occurs when the intraocular pressure is within the normal range, but the optic nerve is still damaged. The cause of NTG is not well understood, but it is believed to be related to poor blood flow to the optic nerve.
- Secondary glaucoma: This type of glaucoma is caused by other underlying medical conditions or medications, such as cataracts, diabetes, trauma, or certain medications.
- Congenital glaucoma: This type of glaucoma is present at birth and is caused by abnormal development of the eye’s drainage system.
- Pigmentary glaucoma: This type of glaucoma is caused by the accumulation of pigment granules in the drainage channels of the eye, which can obstruct the outflow of fluid and lead to increased intraocular pressure.
- Traumatic glaucoma: This type of glaucoma occurs after an eye injury, and is caused by damage to the eye’s drainage system.
How to prevent glaucoma?
While there is no sure way to prevent glaucoma, there are several steps you can take to reduce your risk of developing the condition or slow its progression:
- Regular eye exams: Regular eye exams with an ophthalmologist are important to detect glaucoma early and prevent vision loss. People who are at higher risk of developing glaucomas, such as older adults and people with a family history of the condition, should have regular eye exams starting at age 40 or earlier if they have other risk factors.
- Control underlying medical conditions: People with underlying medical conditions such as diabetes, high blood pressure, and heart disease, should work closely with their healthcare providers to manage these conditions, as they can increase the risk of developing glaucoma.
- Maintaining healthy eye pressure: Eye pressure within a healthy range can help prevent damage to the optic nerve. This can be done by using medications, laser therapy, or surgery as prescribed by the ophthalmologist.
- Eat a healthy diet: Eating a diet that’s rich in fruits, vegetables, and whole grains can help maintain overall health and reduce the risk of developing glaucoma.
- Wear eye protection: Eye injuries can increase the risk of developing glaucoma, so it’s important to wear eye protection when participating in activities that could cause eye injury, such as sports or using power tools.
- Quitting smoking: smoking is associated with an increased risk of developing glaucoma, and it can also lower the effectiveness of glaucoma medications.
Is glaucoma hereditary?
heredity can play a role in the development of glaucoma, specifically primary open-angle glaucoma (POAG) which is the most common type of glaucoma. Studies have shown that people with a family history of glaucoma are more likely to develop the condition than those without a family history. Having a parent or sibling with POAG increases the risk by 4-9 times.
Glaucoma is often called the “silent thief of sight” because it usually has no symptoms in its early stages and can progress unnoticed. For this reason, regular eye exams with an ophthalmologist are important for the early detection and prevention of vision loss.
During a comprehensive eye exam, your ophthalmologist will check for signs of glaucoma using a variety of tests. These may include:
- Intraocular pressure test: This test measures the pressure inside your eye using a device called a tonometer. A high reading can indicate glaucoma, but it’s worth noting that some people with glaucoma may have normal intraocular pressure, which is known as normal tension glaucoma.
- Visual field test: This test measures your peripheral vision and can detect early loss of vision caused by glaucoma.
- Dilated eye exam: Drops are placed in your eyes to widen (dilate) the pupils. This allows your ophthalmologist to get a better view of the inside of your eye, including the optic nerve, which can be damaged by glaucoma.
- Optic nerve imaging: your ophthalmologist may use special imaging tests such as Optical Coherence Tomography (OCT) or Heidelberg Retina Tomography (HRT) to take detailed pictures of the optic nerve and detect any signs of damage caused by glaucoma.
- Pachymetry: to measure the corneal thickness which can be an indicator of the risk of developing glaucoma.