Glaucoma is an umbrella term for eye diseases that damage the optic nerve (communication pathway between the eye and the brain). Increased intraocular pressure (IOP) causes glaucoma, which eventually damages the optic nerve. This leads to vision loss and blindness if left untreated.
The front part of the eye produces aqueous humor (the clear fluid that nourishes and gives eye shape). Eye fluid travels through the pupil (opening at the center of the eye that allows light to enter) and drains through a drainage angle (trabecular meshwork of canals). If the balance of fluid is off even slightly, eye pressure can increase, causing glaucoma.
Glaucoma affects about 3 million Americans and is a leading cause of blindness worldwide. It has been called the "silent thief of sight" because there are usually no symptoms until the late stages of the disease.1
There is no cure for glaucoma, but it can be treated and managed to slow progression and prevent vision loss if caught early. Glaucoma is diagnosed during a routine comprehensive eye exam by a licensed ophthalmologist.
Types of Glaucoma
Optic nerve damage caused by an increase in eye pressure can happen in various ways, leading to different types of glaucoma.
The most common type of glaucoma is primary open-angle glaucoma, which accounts for 74% of all glaucoma cases.3
Open-Angle Glaucoma
Open-angle glaucoma occurs when the drainage angle is open, but a clog of the trabecular meshwork disrupts the flow of eye fluid. This leads to an increase in eye pressure.
Many people don’t know they have increased eye pressure until advanced stages of the disease when vision changes bring them to an eye doctor.
Acute Angle-Closure Glaucoma
Angle-closure glaucoma occurs when the drainage angle is blocked. This blockage causes a sudden spike in eye pressure, resulting in immediate vision changes, such as:
Hazy or blurred vision
Headache
Severe eye pain
Nausea or vomiting
Rainbows or halos around light
Angle-closure glaucoma is a medical emergency and can lead to blindness if not treated early.
Secondary Glaucoma
Secondary glaucoma is when an underlying medical condition or event causes an increase in IOP. Causes of secondary glaucoma can include:
Inflammation
Eye injury or blunt force trauma
Diabetes complications
Certain medications (steroids)
Secondary glaucoma can stem from either open-angle or angle-closure glaucoma. Types of secondary glaucoma include:
Steroid-induced glaucoma from the use of steroid eye drops or systemic steroids
Trauma-induced glaucoma,which is typically caused by blunt force trauma
Uveitic glaucoma, which causes inflammation in the middle layer of the eye
Neovascular glaucoma, when newly formed blood vessels cover the drainage angle. It's typically associated with diabetes
Exfoliative glaucoma,which is caused by a flaky material clogging the drainage angle
Pigmentary glaucoma,whichis caused by pigment flakes from the iris blocking the drainage system
Childhood Glaucoma
Childhood glaucoma, also called congenital glaucoma, occurs when an infant's drainage canal does not develop properly before birth. It’s typically diagnosed within the first year of life and is often hereditary. This type of glaucoma is rare.
If treated early, children with glaucoma experience minimal vision changes and lead full lives.
Normal-Tension Glaucoma
Normal-tension glaucoma is also called normal pressure glaucoma or low pressure glaucoma. It’s a form of open-angle glaucoma that damages the optic nerve in the absence of elevated eye pressure.
Many people with normal-tension glaucoma also experience:
Problems with the vascular system (blood vessels)
Migraine headaches
Cold feet and hands
Low blood pressure
Optic nerve hemorrhages
What Causes Glaucoma?
Glaucoma is caused by fluid build-up in the front of the eye, leading to increased eye pressure in the optic nerve. This high pressure is also called ocular hypertension. However, not everyone with ocular hypertension develops glaucoma.
If left untreated, glaucoma will cause irreversible damage and eventually blindness. People can get glaucoma in one or both eyes.
Anyone can get glaucoma, but certain groups and factors increase the risk. These groups and factors include:
Anyone over age 60
African Americans over age 40
Family history of glaucoma
Diabetes or uncontrolled blood sugar
Eye injuries
Severe myopia (nearsightedness)
History of steroid use
High blood pressure (hypertension)
Low blood pressure (hypotension), including people with hypertension who are overtreated with medication
Thinner corneas (less than .5 mm)
Symptoms of Glaucoma
Glaucoma typically doesn't have any symptoms until the later stages, when vision starts to change. The first warning signs are blind spots in your peripheral vision (side vision).
Routine comprehensive eye exams are critical in maintaining eye health and catching early warning signs. It’s essential to see an eye doctor if you notice any vision changes, including:
It’s recommended that anyone over 35 at high risk for glaucoma should get an annual eye exam.
The following are warning signs of a medical emergency. Seek care right away if you experience:
Sudden loss of vision in one or both eyes
Sudden blurry, hazy, or double vision
Flashes of light
Dark spots in your side or central vision
Halos or rainbows around light
Severe eye pain
How is Glaucoma Diagnosed?
Glaucoma is diagnosed during a comprehensive eye exam by a licensed ophthalmologist. The exam consists of a series of tests to check the overall health of the eyes. Many exams dilate the pupils. This allows the eye doctor to look at the retina, optic nerve, and the back of the eye.
Tonometry is another critical eye test that measures intraocular pressure in both eyes. High IOP is a common sign of glaucoma and possible optic nerve damage.
There is no cure for glaucoma, and optic nerve damage is irreversible. However, many glaucoma treatments can help slow the progression of the disease and minimize vision loss.
Medication
The first goal of treatment is to reduce intraocular pressure to prevent further optic nerve damage. Lowering IOP can be done with prescription eye drops, which will have to be administered for the rest of your life.
Various types of medicated eye drops are available, including:
Beta-blockers, which reduce the amount of fluid in the eye, lowering pressure
Alpha-adrenergic agonists, whichincrease outflow and minimize the production of eye fluid
Carbonic anhydrase inhibitors, which reduce eye fluid production
Miotic or cholinergic agents prostaglandins, which increase eye fluid outflow
Prostaglandins,which increase eye fluid outflow
Laser Surgery
Laser therapy is used to treat glaucoma when medications alone do not lower eye pressure. It aims to repair and unblock the drainage angle.
Types of laser therapy used to treat glaucoma include:
Trabeculoplasty opens clogged channels in the drainage angle
Iridotomy creates a small hole in the iris (colored part of the eye) to drain eye fluid
Glaucoma Surgery
Glaucoma surgery is necessary when medication and laser treatment don’t work to reduce eye pressure.
The type of surgery needed depends on the drainage system issue. Options include:
Trabeculectomy (filtering surgery), which opens the sclera (white part of the eye) and removes part of the trabecular meshwork to help eye fluid drain freely
Drainage implant (tube), which is placed on the sclera (white part of the eye) to help fluid drain out of the eye and reduce eye pressure
Cataract surgeryreplacement of the lens (helps focus light on the retina) can help reduce eye pressure for people with narrow-angle glaucoma.
Glaucoma Risks and Complications
Glaucoma is a severe eye disease that can lead to vision loss and blindness if not treated. While the condition is typically not life-threatening, it can affect quality of life.
Because glaucoma can be asymptomatic in the early stages, it’s essential to get routine eye exams.
Can You Prevent Glaucoma?
While glaucoma can’t be cured or prevented, there are lifestyle changes that can help slow disease progression, including:
Annual comprehensive eye exams
Exercise
A healthy diet
Not smoking
Eye protection
Blood sugar and pressure control
Glaucoma Outlook and Prognosis
Catching glaucoma early can slow progression and minimize vision loss and optic nerve damage. People diagnosed with glaucoma will likely use medicated eye drops to maintain normal eye pressure for the rest of their lives.
Laser therapy and glaucoma surgery can also help minimize vision loss and prevent blindness.
Summary
Glaucoma is an umbrella term for eye diseases that damage the optic nerve. The condition is caused by increased intraocular pressure. It results in vision loss and eventual blindness if not treated early.
Glaucoma is typically asymptomatic until the advanced stages of the disease. The first warning sign of glaucoma is changes in peripheral vision (side vision).
Early detection is vital to minimize vision loss and prevent blindness. Glaucoma is diagnosed during an annual comprehensive eye exam. These exams are recommended for anyone experiencing symptoms or with a high risk of developing glaucoma.
Melody Huang is an optometrist and freelance health writer. Through her writing, Dr. Huang enjoys educating patients on how to lead healthier and happier lives. She also has an interest in Eastern medicine practices and learning about integrative medicine. When she’s not working, Dr. Huang loves reviewing new skin care products, trying interesting food recipes, or hanging with her adopted cats.
Amy is a registered nurse who holds a M.S. in nursing from California State University, Sacramento, as well as a B.A. in journalism from California State University, Chico. She is a freelance health writer who brings her deep knowledge of the importance of eye health to Vision Center. Her goal is to combine the worlds of nursing and writing to educate people on common eye conditions and how to prevent vision loss.
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