The following are some of the common questions answered by UMMC ophthalmologists regarding glaucoma care and services.
What causes glaucoma?
There are different theories for the cause of glaucoma, but it is important to understand that, in each of these theories, the end result of glaucoma is progressive damage to the optic nerve (optic neuropathy).
One theory about the cause of glaucoma is based on elevated intraocular pressure. It is important to note that high intraocular pressure is not synonymous with glaucoma. Certain types of glaucoma have normal intraocular pressure.
A clear liquid called aqueous humor circulates in the front portion of the eye. To maintain a healthy level of pressure within the eye, a small amount of this fluid is produced constantly while an equal amount flows out of the eye through a microscopic drainage system. Because the eye is a closed structure, if the drainage area for the aqueous humor (the drainage angle) is blocked, the excess fluid cannot flow out of the eye. Fluid pressure within the eye increases, pushing against the optic nerve and causing damage.
Another theory about the cause of glaucoma is based on compromised blood supply to the optic nerve resulting in progressive damage to the nerve. Many factors may come in to play to cause vascular compromise.
What are the different types of glaucoma?
There are different types of glaucoma, but they can be broadly divided into two groups: chronic open-angle
- Chronic open-angle glaucoma is the most common form of glaucoma in the United States. The drainage angle of the eye becomes less efficient over time, and pressure within the eye gradually increases, possibly resulting in damage to the optic nerve. In some patients, the optic nerve becomes sensitive even to normal eye pressure and is at risk for damage. Treatment is necessary to prevent further vision loss. Risk of developing chronic open-angle glaucoma increases with age.
- Open-angle glaucoma typically has no symptoms in its early stages, and vision remains normal. As the optic nerve becomes more damaged, blank spots develop in the field of vision. You may not notice these blank spots during day-to-day activity until the optic nerve is significantly damaged and these spots become large.
- Closed-angle glaucoma occurs in certain eyes when the iris is very close to the drainage angle. These eyes are often small and farsighted, and the iris could be sucked into the drain and block it completely. Since the fluid cannot exit the eye, pressure can build up rapidly, resulting in acute closed-angle attack.
Symptoms may include:
- Blurred vision
- Severe pain
- Rainbow halos around lights
This situation is a true eye emergency. If you have any of these symptoms constantly or even intermittently, call your ophthalmologist immediately. If not treated quickly, this type of glaucoma can result in blindness.
Who is at risk for glaucoma?
Your ophthalmologist considers different kinds of information to determine your risk for developing the disease. The most important risk factors include:
- Elevated intraocular pressure
- Family history of glaucoma
- African or Spanish ancestry
- Farsightedness (closed-angle) or nearsightedness (open–angle)
- Past eye injuries
- Thinner central corneal thickness
- Systemic health problems including diabetes, migraine headaches, and poor circulation
Your ophthalmologist will weigh all these factors before deciding whether you need treatment or monitoring as a glaucoma suspect, which means your risk of developing glaucoma is higher than normal, and you need to be followed closely to detect early signs of glaucoma.
How is glaucoma detected?
Regular eye examinations by your eye doctor are the best way to detect glaucoma. A glaucoma screening that only checks pressure is insufficient to determine if you have glaucoma.
During a glaucoma evaluation, the ophthalmologist will measure your intraocular pressure (tonometry), inspect the drainage of your eye (gonioscopy), evaluate any presence of optic nerve damage (ophthalmoscopy), and test the field of vision of each eye (visual field testing of perimetry). Photography of the optic nerve or computerized imaging may be recommended. These tests may need to be repeated on a regular basis to monitor any changes in your condition.
How is glaucoma treated?
As a rule, damage caused by glaucoma cannot be reversed. Eye drops, laser surgery, and surgery (in the operating room) are used to help prevent further damage. In some cases, oral medications may also be prescribed. With any type of glaucoma, periodic examinations are important to prevent vision loss. Glaucoma can progress without your knowledge, hence the need for routine follow-up visits to check the progression of the disease and adjust therapy as needed.
Glaucoma is usually controlled with medicated eye drops each day. The drops lower eye pressure by reducing aqueous production or increasing outflow through the drainage angle or other tissue. Never change or stop taking medication without consulting your ophthalmologist. Glaucoma medications can preserve vision but may also produce side effects.
Notify your ophthalmologist if you think you are experiencing side effects, including:
- A stinging or itching sensation
- Blurred vision
- Changes in breathing (especially with asthma or emphysema)
- Changes in energy level
- Changes in eye color
- Changes in pulse and heartbeat
- Changes in sense of taste
- Dry mouth
- Red eyes or redness of the skin surrounding the eyes
All medications can have side effects or possible interaction with other medicines. It is important to make a list of all medications you regularly take and share it with every doctor you see.
Laser surgery treatment may be recommended for different types of glaucoma. In open-angle glaucoma, the drain itself is treated. The laser is used to modify the drain (trabeculoplasty) to help control eye pressure. In closed-angle glaucoma, the laser creates a hole in the iris (iridotomy) to improve the flow of aqueous fluid to the drain.
When surgery in the operating room is needed to treat glaucoma, your ophthalmologist uses fine, microsurgical instruments to create a new drainage channel for the aqueous fluid to leave the eye. Surgery is recommended if your ophthalmologist feels it is necessary to prevent further damage to the optic nerve.
What is the patient's part in treatment?
Treatment for glaucoma requires teamwork. Your ophthalmologist can prescribe treatment for glaucoma, but only you can make sure to follow your doctor’s instructions and use your eyedrops.
Once you are taking medication for glaucoma, your ophthalmologist will want to see you regularly. Typically, you will need to follow up every three to four months, depending on treatment needs.
How often should I be screened for glaucoma?
Regular medical eye exams may help prevent unnecessary vision loss. People with risk factors listed above have a higher risk for developing glaucoma and require more frequent screening examinations.
Recommended intervals for eye exams:
- Ages 20-29
Individuals of African or Spanish descent or those with a family history of glaucoma should have an eye exam every three to five years. Others should have an exam at least once during this period.
- Ages 30-39
Individuals of African or Spanish descent or those with with family history of glaucoma should have an eye exam every two to four years. Others should have an exam at least twice during this period.
- Ages 40-64
Everyone in this age group should have an eye exam at least every two to four years.
- Ages 64 or older
Everyone in this age group should have an eye exam at least every one to two years.