What is Glaucoma? Glaucoma Definition
Glaucoma is a disease that is caused by damage to the eye’s optic nerve that is often the result of fluid build-up in the eye. This extra fluid increases the pressure in the eye, called intraocular pressure, causing damage to the optic nerve, which sends images to the brain. This fluid (called aqueous humor) flows throughout the inside of the eye and is normally drained through a tissue called the trabecular meshwork, located at the angle where the cornea and iris meet. Eye pressure increases when the fluid is overproduced or the drainage system isn’t working properly, preventing the fluid from flowing out at a normal rate. As the optic nerve gradually deteriorates, those with glaucoma will develop blind spots in their visual field.
Because glaucoma slowly gets worse over time, most people won’t be diagnosed until later in life. If the damage to the eye worsens, glaucoma may cause permanent vision loss. Glaucoma can, in rare cases, lead to total blindness.
Two Major Types of Glaucoma
There are two major types of glaucoma: primary open-angle glaucoma and angle-closure glaucoma. However, there are many more which we will cover as well.
Primary open-angle glaucoma
Primary open-angle glaucoma is the most common type of glaucoma. With this type of glaucoma, the drainage angle between the cornea and iris is open, but the trabecular meshwork is partially blocked. Slowly over time, the eye fails to drain fluid as well as it should. Consequently, intraocular pressure builds and begins to damage the optic nerve. Primary open-angle glaucoma is painless and does not cause vision changes immediately. In fact, it happens so slowly that most people affected by it lose vision before they’re aware of the problem.
Angle-closure glaucoma
Angle-closure glaucoma, also known as “closed-angle glaucoma” or “narrow-angle glaucoma”, develops when the iris is too close to the drainage angle in the eye. If the iris is too close, it can end up blocking the fluid drainage. Intraocular pressure rises very quickly when the drainage angle is fully blocked. This is called an acute attack and is an eye emergency. Without immediate care, this can cause blindness. Some people naturally have narrow drainage angles, which increases their risk of angle-closure glaucoma.
Chronic angle-closure glaucoma is developed very slowly over time. Most people who have chronic angle-closure glaucoma don’t experience symptoms until later on, meaning that they usually aren’t aware that they have it until the damage is severe or if they experience an attack. Acute angle-closure glaucoma happens suddenly and is considered a medical emergency. Certain populations are more susceptible, including those of Asian descent and those who have smaller eyes.
Other types of glaucoma include:
Normal-tension glaucoma
Normal-tension glaucoma is caused by optic nerve damage that has occurred despite normal intraocular pressure. The cause of normal-tension glaucoma is still being researched; however, researchers hypothesize that it may be due to individuals having sensitive optic nerves or insufficient amounts of blood being supplied to the optic nerve. The limited blood flow may be caused by atherosclerosis, which is a build-up of plaque (fatty deposits) in the arteries or other health factors that might impair circulation.
Pigmentary glaucoma
Pigmentary glaucoma is caused by the build-up of pigment granules in the drainage channels, which slow or block the fluid from exiting the eye. Physical activity, such as jogging, can stir up the pigment granules, displacing them and leading to intermittent pressure elevations.
Congenital glaucoma
Children and infants can experience glaucoma. Glaucoma in children may be present from birth or develop early on in life. In these cases, optic nerve damage may be the result of drainage blockages or underlying medical conditions.
8 Glaucoma Symptoms You Need to Know and Signs of Glaucoma
Glaucoma is a category of diseases affecting the optic nerve that can lead to permanent loss of vision. Because there are different types of glaucoma, these can present different symptoms. However, sometimes there are no warning signs, which is usually the case with open-angle glaucoma.
If you do notice any of the symptoms below, seek immediate medical attention. However, your best defense is seeing your eye doctor yearly for a dilated eye exam.
1. Loss of peripheral or side vision
Loss of your peripheral vision is usually the first sign of glaucoma triggered vision loss. However, this may not be noticed until the condition has severely progressed.
2. Seeing halos around lights
Seeing rainbow-colored halos around lights or feeling unusually sensitive to light can be a sign of glaucoma.
3. Vision loss
Suddenly losing your vision is a good indicator of glaucoma.
4. Redness in the eye
Redness in the eye often coincides with pain. This may be a sign of infection, injury, or acute glaucoma, depending on other symptoms the patient is experiencing.
5. An eye that looks cloudy or hazy
The most common early sign of glaucoma in children is cloudy or hazy-looking corneas.
6. Nausea or vomiting
When accompanied by severe eye pain, nausea or vomiting may be a sign of angle closure glaucoma.
7. Pain in both the eye and the head
Pain in the head and the eye is a common symptom of angle-closure glaucoma. This type of glaucoma can develop very quickly, so if you experience this symptom be sure to seek medical care immediately.
8. Narrowing of vision (tunnel vision)
The last sign of glaucoma is the loss of vision around the edges of your visual field. As stated earlier, this symptom often goes unnoticed until the condition worsens.
Who is at Risk for Glaucoma?
One of the best ways to prevent glaucoma is by knowing your family’s medical history and understanding whether or not you are at increased risk to develop glaucoma. Those who are at higher risk for glaucoma should get an eye exam every year. Glaucoma tends to run in families, and usually affects adults over 40. However, younger people can be at risk for glaucoma as well. You may be at risk for glaucoma if:
You have a family member who has had glaucoma. Scientists now have found genes linked to high intraocular pressure and optic nerve damage.
You are of Asian, African-American, Hispanic, Inuit, Irish, Russian or Scandinavian descent
You are over age 40, and even more so if you are over age 60.
You have diabetes.
You have hypertension or extremely low blood pressure.
You have had an eye injury in the past.
You have poor vision, specifically if you have extreme nearsightedness or a very thin cornea.
You take specific steroid medications, such as prednisone.
Some people may be at risk for glaucoma if they have optic nerves that are sensitive to normal eye pressure. Visiting your optometrist regularly can help identify early signs of damage to the optic nerve.
Glaucoma Causes
Glaucoma is generally caused by a failure of the eye to maintain the correct balance of intraocular fluid, also known as aqueous humor, in the eye. The underlying reasons for this imbalance are usually related to the kind of glaucoma one has. In healthy eyes, the fluid in the eye flows out of the eye through a mesh-like channel. If there is a blockage in this drainage system, the fluid builds up.
The eye’s intraocular pressure allows it to retain its globe-like shape and ability to see. When something impacts the ability of the eye to regulate its intraocular pressure, the eye pressure can rise to high levels, resulting in glaucoma.
Unlike a balloon, the eye isn’t able to relieve pressure by deflating. Instead, the intraocular pressure continues to build and push against the optic nerve. Eventually, the fibers of the optic nerve become permanently damaged and vision is lost.
Other causes of glaucoma include injury to the eye, severe eye infection, inflammatory conditions, or blocked blood vessels inside the eye. While it’s rare, eye surgery for another condition can also trigger glaucoma. Glaucoma often affects both eyes, but may be more severe in one than the other.
The loss of vision by glaucoma cannot be reversed. However, most people with glaucoma who follow their treatment plan are able to keep the vision they have by lowering their eye pressure.
Prevention
There are several things you can do to detect glaucoma early on, before experiencing vision loss: 1. Get regular dilated eye exams Regular eye exams can detect glaucoma early on, before you’ve experienced significant damage like vision loss. It’s recommended that you have a comprehensive eye exam every:
Two years if you’re between 40-55 years old
One to two years if you’re 55 to 64 years old
One year if you’re over 65
One year if you have a history or family history of glaucoma
2. Know your family’s health history Because glaucoma tends to run in families, be sure to look into your family’s health history. You will need more frequent screening if you are at risk. 3. Exercise regularly Safe, regular exercise can prevent glaucoma by relieving eye pressure. Speak with your doctor to discuss what kind of exercise is right for you. 4. Use prescribed eye drops regularly Prescribed glaucoma eye drops can reduce the risk that high intraocular pressure will become glaucoma, in those who naturally have high eye pressure. These eye drops must be prescribed by your doctor and used regularly in order to be effective. 5. Keep your eyes protected Serious injury to the eye can lead to glaucoma. To protect your eyes, wear eye protection (safety glasses) when using power tools or when playing racket sports.
Article Submitted by:
Joana De los Santos
Technical Representative at Eye Love