Glaucoma is a disease of the optic nerve, the part of the eye that carries images we see to the brain.
The front of the eye is filled with a fluid, called aqueous humor. This fluid is mostly water, and the
main purpose is to inflate and maintain the shape of the eye. This fluid is very similar to water in a
balloon, and sometimes the eye pressure can be too high. In such cases, pressure is placed on the optic
nerve. This elevated pressure causes damage to the optic nerve. If the optic nerve is damaged, then vision
cannot be transmitted from the eye to the brain, resulting in blindness. Unfortunately, damage to the
optic nerve is not typically reversible. Once vision is lost, it cannot be restored. Therefore, screening
and prevention are the keys to good glaucoma care. If detected, glaucoma is often treated with topical
medications (eye drops), laser treatments or surgery.
There are many forms of glaucoma, but the hallmarks of all forms of glaucoma are damage to the optic nerve
and visual field loss. New risk factors for glaucoma are always being discovered, but elevated intraocular
pressure, increasing age, African-Americans and a family history of glaucoma remain among the highest risk
Common types of glaucoma include:
- Primary open angle glaucoma (POAG) - Open angle glaucoma is the most common form of glaucoma.
It is generally painless and slowly progressive. It is thought to be caused by changes in the drainage tissues
of the eye. Although this type of glaucoma usually involves both eyes, it can be asymmetric in severity.
- Angle closure glaucoma - More frequent in women, angle closure glaucoma is caused by anatomical
changes in the relationship between the drainage system of the eye (the angle), iris and lens. The normal drainage
outflow becomes blocked and the eye pressure elevates. This form of glaucoma can occur rapidly and can be painful.
It is frequently treated with a laser. The laser opens a hole in the iris, restoring a more normal ocular anatomy
and aqueous flow.
- Pigmentary glaucoma - This type of glaucoma is seen when pigment from the back of the iris deposits
in the drainage tissues of the eye. This pigment causes a blockage and elevated eye pressure. It occurs more
frequently in myopic (near-sighted) patients.
- Pseudoexfoliation glaucoma - A particular material, thought to be from the lens of the eye, deposits
in the drainage tissues and results in glaucoma.
- Low tension glaucoma (LTG) - Low tension or normal tension glaucoma presents as progressive visual
field loss and optic nerve damage. However, the intraocular pressure generally remains within a normal range.
Evaluation and Diagnosis
Screening for glaucoma can be done during a routine eye exam. The intraocular pressure is measured and a
slit-lamp exam is performed, which is a microscopic exam of the anterior aspect of the eye. In addition,
the optic nerve is examined for any evidence of abnormalities (cupping).
If the examination is suspicious for glaucoma, more specific studies can be done. These include visual
field testing, optic nerve photography, and OCT (optical coherence tomography). These studies may not
only help make the diagnosis of glaucoma, but help establish a baseline. Glaucoma in its most common
form is a slowly progressive disease. Therefore, establishing a baseline helps assess the rate of disease
progression and aid in the selection of treatment options.
Typically, for the most common form of glaucoma (open angle glaucoma), treatment options will include
medications, laser treatments, or eye surgery. Frequently, a combination of these options may be used.
The goal of glaucoma treatment is to decrease intraocular pressure and prevent damage to the optic nerve.
At the beginning of treatment, the doctor will generally recommend medication or a combination of eye
drops and oral medications for the specific condition.
Glaucoma is a chronic condition that is not "cured" by the treatment; it requires continued monitoring.
When deciding on which treatment options, it is necessary for the physician and patient to thoroughly
discuss the risks and benefits.
Several different classes of glaucoma medications are available, including beta blockers, prostaglandin
analogues, alpha adrenergic agonists, miotic, epinephrine compounds and oral and topical carbonic anhydrase
inhibitors. These medications work by either reducing the rate at which fluid in the eye is produced or
increasing the outflow of fluid from the eye.
Laser treatment can open the drainage angle and reduce intraocular pressure. Although surgery can be done to
create a new passage for fluid drainage, it is usually reserved for cases that cannot be controlled by
medication or if laser treatment was not successful.
Eye Drops - All eye drops may cause a burning or stinging sensation at first. This is often
due to the antibacterial agent present in the drop solution, not the drug itself. While uncomfortable, it only
lasts for a few seconds. It is important that you take your medication exactly as prescribed.
Since eye drops are absorbed into the bloodstream, it is important that you tell your doctor about all other
medications you are taking. Some drugs can be dangerous when mixed with others. Ask your doctor or pharmacist
if the medications you are taking together are safe. To minimize absorption into the bloodstream and maximize
the amount of drug absorbed into the eye, close your eyes for one to two minutes after administering your drops
and press lightly against the nasal corner of your eyelids to close the tear duct that drains into the nose.
Oral Medications - Sometimes, drops are not enough to control intraocular pressure. When this
is the case, pills may also be prescribed. These pills also serve to lessen the production of fluid in the eye.
The medication is usually taken two to four times daily. It is important to share this information with your
other doctors so that they can best prescribe medications for you that will not cause potentially dangerous
Laser surgery has become increasingly popular as an intermediate step between drugs and traditional surgery.
The most common type performed for open-angle glaucoma is called trabeculoplasty. This procedure takes 10 to
20 minutes, is painless and can be performed in either a doctor's office or outpatient facility.
The most common form of traditional surgery is called a trabeculectomy. In this procedure, the surgeon removes
a small section of the trabecular meshwork to allow the aqueous humor to drain more easily, reducing pressure
in the eye. This procedure is usually done under local anesthesia, either as an outpatient or with a brief
hospital stay since your doctor will want to see you the day after surgery. It is important to note that your
eyes may not have their normal visual acuity for several weeks following this procedure. Although trabeculectomy
is a relatively safe surgical procedure, about one-third of patients develop cataracts within five years of
surgery. After trabeculectomy, most patients are able to discontinue all anti-glaucoma medications. Ten to 15
percent of patients require additional surgery.
Minimally invasive glaucoma surgery is associated with much fewer side effects and
complications and faster recovery, but the pressure-lowering effect is less than
that of traditional glaucoma surgery. These less invasive surgeries may be appropriate
for you if you have mild or moderate vision loss from glaucoma. Minimally invasive
glaucoma surgery is frequently done in conjunction with cataract surgery.
Frequently Asked Questions
What are the symptoms of glaucoma?
In most cases, glaucoma has no symptoms. By the time an individual experiences decreased vision, the disease is
frequently in its later stages.
The symptoms depend on the type of glaucoma the individual has. Those who have chronic glaucoma may not be aware
of any symptoms because the disease develops slowly and patients rarely notice loss of peripheral vision. Those
who have an acute form of glaucoma may develop severe symptoms because ocular pressure rises quickly. They may
experience blurred vision, especially at night, halos or rainbows around lights, severe headaches or eye pain
Since early warning signs of glaucoma are rare, it is important to have regular medical eye exams especially for
those at risk.
Patients who may be at risk for glaucoma include:
- Those over 60 (in African Americans, the risk is present at age 40 and older)
- A family history of glaucoma
- Race (African Americans and Latinos are significantly more likely to get glaucoma)
- Certain medical conditions (diabetes, high blood pressure, heart disease)
- Physical injuries of the eye
Is blindness caused by glaucoma preventable?
Regular diagnostic examinations by an ophthalmologist are important in preventing loss of vision. Although there
is no way to reverse damage, if glaucoma is diagnosed and treated early, blindness almost always is preventable.
What's the best treatment for glaucoma: surgery or medication?
Quality of life is an important factor in the treatment of any chronic ailment. It is important to make a decision
as to whether you want to live with significant side effects. You should first consider whether there is a way to
eliminate the side effects of the medications you are taking. Talking with your ophthalmologist is the best approach
to identifying possible ways to resolve the problem of medication side effects.
If you are still suffering from intolerable side effects, or if your glaucoma is uncontrolled, then surgery may
be an option.
Glaucoma surgery is safer and more effective than ever. Surgery for uncomplicated open-angle glaucoma, when
performed as an initial surgical procedure in a patient who has not had previous intraocular surgery, is highly
effective. The chance of complications or surgical failure increases with previous intraocular surgery, complicated
glaucoma, having to redo the operation for glaucoma and severe near-sightedness.
Is glaucoma painful?
Generally, the answer is no. In some forms of glaucoma, the pressure may become extremely elevated (above 40 mm high).
In such cases the patient may experience pain, blurry vision, halos, or nausea and vomiting.