Glaucoma is a disease that damages your eye’s optic nerve. It usually happens when fluid builds up in the front part of your eye. That extra fluid increases the pressure in your eye, damaging the optic nerve.
Glaucoma typically affects your peripheral vision first. This is why it is such a sneaky disease: You can lose a great deal of your vision from glaucoma before you are aware anything is happening. If uncontrolled or left untreated, glaucoma can eventually lead to blindness.
Signs and Symptoms of Glaucoma
Glaucoma often progresses undetected, typically causing no pain and producing no symptoms, until the optic nerve already has been irreversibly damaged, with varying degrees of permanent vision loss.
But there are other forms of the disease (specifically, acute angle-closure glaucoma), where symptoms of blurry vision, halos around lights, intense eye pain, nausea, and vomiting occur suddenly.
What Causes Glaucoma?
The cause of glaucoma is generally a failure of the eye to maintain an appropriate balance between the amount of fluid produced inside the eye and the amount that drains away. The eyeball needs internal fluid pressure to retain its globe-like shape and ability to see. But when glaucoma damages the ability of internal eye structures to regulate intraocular pressure (IOP), eye pressure can rise to dangerously high levels and vision is lost.
Types of Glaucoma
The two major categories of glaucoma are open-angle glaucoma and narrow-angle glaucoma. The angle refers to the structure inside the eye that is responsible for fluid drainage from the eye, located near the junction between the iris and the front surface of the eye near the periphery of the cornea.
Open-angle is the most common type of glaucoma. It happens gradually, where the eye does not drain fluid as well as it should (like a clogged drain). As a result, eye pressure builds and starts to damage the optic nerve. This type of glaucoma is painless and causes no vision changes at first. Some people can have optic nerves that are sensitive to normal eye pressure. This means their risk of getting glaucoma is higher than normal. Regular eye exams are important to find early signs of damage to their optic nerve.
Narrow-angle glaucoma occurs type happens when the iris is very close to the drainage angle in their eye, blocking the drainage angle. When the drainage angle gets completely blocked, eye pressure rises very quickly. This is called an acute attack. It is a true eye emergency, and you should call your eye doctor right away or you might go blind.
Signs of an acute angle-closure glaucoma attack include:
- Blurry Vision
- Severe eye pain
- Focusing skills
- Halos around lights
Many people with angle-closure glaucoma develop it slowly. This is called chronic angle-closure glaucoma. There are no symptoms at first, so they don’t know they have it until the damage is severe or they have an attack.
Angle-closure glaucoma can cause blindness if not treated right away.
How Is Glaucoma Detected?
The only sure way to diagnose glaucoma is with a complete eye exam. A tonometer is used to measure your intraocular pressure (IOP). Your eye typically is numbed with eye drops, and a small probe gently rests against your eye's surface. Other types of tonometers direct a puff of air onto your eye's surface to indirectly measure IOP.
An abnormally high IOP reading indicates a problem with the amount of fluid inside the eye. Either the eye is producing too much fluid, or it's not draining properly.
During a glaucoma exam, your eye doctor will:
- measure your eye pressure
- inspect your eye’s drainage angle
- examine your optic nerve for damage
- test your peripheral (side) vision
- take a picture or computer measurement of your optic nerve
- measure the thickness of your cornea
Another method for detecting or monitoring glaucoma is the use of instruments to create images of the eye's optic nerve and then repeating this imaging over time to see if changes to the optic nerve are taking place, which might indicate progressive glaucoma damage. Imaging methods include scanning laser polarimetry (SLP), optical coherence tomography (OCT), and confocal scanning laser ophthalmoscopy.
Glaucoma damage is permanent—it cannot be reversed. But medicine and surgery help to stop further damage. Depending on the severity of the disease, treatment for glaucoma can involve the use of medications, conventional surgery, laser surgery or a combination of these treatments. Medicated eye drops aimed at lowering IOP usually are tried first to control glaucoma.
All glaucoma surgery procedures (whether laser or non-laser) are designed to accomplish one of two basic results: decrease the production of intraocular fluid or increase the outflow (drainage) of this same fluid. Occasionally, a procedure will accomplish both.
Currently the goal of glaucoma surgery and other glaucoma therapy is to reduce or stabilize intraocular pressure (IOP). When this goal is accomplished, damage to ocular structures – especially the optic nerve – may be prevented.
No matter the treatment, early diagnosis is the best way to prevent vision loss from glaucoma. See your eye doctor routinely for a complete eye examination, including a check of your IOP.
People at high risk for glaucoma due to elevated intraocular pressure, a family history of glaucoma, advanced age or an unusual optic nerve appearance may need more frequent visits to the eye doctor.