Glaucoma & Treatment
Glaucoma refers to a category of eye disorders often associated with a dangerous buildup of internal eye pressure (intraocular pressure or IOP), which can damage the eye's optic nerve – the structure that transmits visual information from the eye to the brain.
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.
Glaucoma is currently the second leading cause of blindness in the United States, with an estimated 2.5 million Americans being affected by the disease. Due to the aging of the U.S. population, it’s expected that more than 3 million Americans will have glaucoma by the year 2020.
Signs and Symptoms of Glaucoma
Glaucoma is often referred to as the "silent thief of sight," because most types typically cause no pain and produce no symptoms. For this reason, glaucoma often progresses undetected 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. If you have these symptoms, make sure you immediately see an eye care practitioner or visit the emergency room so steps can be taken to prevent permanent vision loss.
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. Underlying reasons for this imbalance usually relate to the type of glaucoma you have. Just as a basketball or football requires air pressure to maintain its shape, 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 types of glaucoma are chronic or primary open-angle glaucoma (POAG) and acute angle-closure 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. Some of the more common types of glaucoma include:
How is glaucoma detected?
During routine eye exams, 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. 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.
Additional tests 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. Instruments used for this purpose include scanning laser polarimetry (SLP), optical coherence tomography (OCT), and confocal scanning laser ophthalmoscopy. Visual field testing is another way to monitor whether blind spots are developing in your field of vision from glaucoma damage to the optic nerve. Visual field testing involves staring straight ahead into a machine and clicking a button when you notice a blinking light in your peripheral vision. The visual field test may be repeated at regular intervals so your eye doctor can determine if there is progressive vision loss. An ophthalmoscope also may be used to view internal eye structures, to make sure nothing unusual interferes with the outflow and drainage of eye fluids. Ultrasound biomicroscopy also may be used to evaluate how well fluids flow through the eye's internal structures. Gonioscopy is the use of special lenses that allow your eye doctor to visually inspect internal eye structures that control fluid drainage.
Depending on the severity of the disease, treatment for glaucoma can involve the use of medications, conventional (bladed) surgery, laser surgery or a combination of these treatments. Medicated eye drops aimed at lowering IOP usually are tried first to control glaucoma.
Because glaucoma is often painless, people may become careless about strict use of eye drops that can control eye pressure and help prevent permanent eye damage. In fact, non-compliance with a program of prescribed glaucoma medication is a major reason for blindness resulting from glaucoma. If you find that the eye drops you are using for glaucoma are uncomfortable or inconvenient, never discontinue them without first consulting your eye doctor about a possible alternative therapy.
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 care practitioner 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.