Glaucoma is a disease of the optic nerve-the part of the eye that carries the image we see to the brain. The optic nerve is made up of many nerve fibers and when damage occurs to these fibers, blind spots develop. These blind spots usually go undetected until the optic nerve is significantly damaged. If the entire nerve is destroyed, blindness results.
Early detection and treatment by your ophthalmologist (Eye M.D.) are the keys
to preventing optic nerve damage and blindness from glaucoma.
Glaucoma is a leading cause of blindness in the United States especially for
older people. However, it is important to note that loss of sight from glaucoma
could be prevented with early treatment.
What causes glaucoma?
What are the different Types of
glaucoma?
Who is at risk for glaucoma?
How is glaucoma detected?
How is glaucoma treated?
Medication
Laser Surgery
What is your part in treatment?
How often should I get my eyes
screened for glaucoma?
Links
There are different theories for the cause of glaucoma. It is important
to understand that the end result for all the theories is progressive
damage to
the optic nerve (optic neuropathy).
One such theory is based on elevated intraocular pressure. It is
important to note that high intraocular pressure is not synonymous
with glaucoma. There
are certain types of glaucoma that have normal intraocular pressure.
A Clear liquid called aqueous humor circulates 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. (DIAGRAM) Because the
eye is a closed structure,
if the drainage area for the aqueous humor –called 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 is based on compromise of the blood supply to the optic nerve resulting in progressive damage to the nerve. There may be many factors that 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
these two groups.
Chronic Open-angle glaucoma: this is the commonest form of glaucoma in the
United States. The risk of developing chronic open angle glaucoma increases
with age. 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.
Typically open angle glaucoma has no symptoms in its early stages and vision
remains normal. As the optic nerve becomes more damaged blank spots begin to
develop in the field of vision. You typically won’t notice these blank
spots in your day to day activity until the optic nerve is significantly damaged
and these spots become large.
Closed –angle glaucoma: In
certain eyes, the iris could be very close to the drainage angle. These eyes
are often small and farsighted and the iris
could be sucked into the drain and could block it completely. Since the fluid
cannot exit the eye, pressure could build up rapidly inside the eye resulting
in acute closed angle attack. Symptoms may include: blurred vision, severe
pain, headaches, rainbow-colored halos around lights, nausea and vomiting.
This is a true eye emergency and if you have any of these symptoms constantly
or intermittently call your ophthalmologist immediately.
If not treated quickly, this type of glaucoma can result in blindness. Majority
of patients with closed angle glaucoma develop it slowly without any symptoms
prior to attack.
Your ophthalmologist considers different kinds of information to determine your risk for developing the disease. The most important risk factors include:
Age
Elevated intraocular pressure
Family history of glaucoma
African or Spanish –American ancestry
Far sightedness (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 this factors before deciding whether you
need treatment or whether you need to be followed as a glaucoma suspect.
These means your risk of developing glaucoma is higher than normal and you
need to be followed closely to detect early signs of glaucoma.
Regular eye examinations by your eye doctor are the best ways to detect
glaucoma. A glaucoma screening that only checks pressure is insufficient
to determine
if you have glaucoma. The only way to detect this is with a complete eye
exam.
During your glaucoma evaluation your ophthalmologist will measure your
intraocular pressure ( tonometry) inspect the drainage of your eye (gonioscopy)
evaluate
for the 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.
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 to watch for disease progression and adjustment of therapy as needed from time to time.
Glaucoma is usually controlled with eye drops taken daily. These medications
lower eye pressure by reducing aqueous production or increasing out flow through
the drainage angle or other tissue.
Never change or stop taking your medication without consulting your ophthalmologist.
If you are about to run out of your medication, call your ophthalmologist to
have you medication refilled.
Glaucoma medications can preserve your vision but may also produce side effects.
You must notify your ophthalmologist if you think you may be experiencing side
effects.
Some eye drops may cause:
A stinging or itching sensation
Red eyes or redness of the skin surrounding the eyes.
Changes in pulse and heartbeat
Changes in energy level
Changes in breathing (especially with asthma/ emphysema)
Dry mouth
Changes in taste sense
Headaches
Blurred vision
Changes in eye color
All medications can have side effects or can interact with other medications. Therefore, it is important that you make a list of the medication you regularly take and share this list with each 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.
Surgery in the operating room
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 your part in treatment?
Treatment for glaucoma requires teamwork between you and your doctor. Your
ophthalmologist can prescribe treatment for glaucoma but only you can make
sure you follow your doctor’s instructions and take your eye drops.
Once you are taking medication for glaucoma your ophthalmologist will want
to see you more frequently .Typically you will need to follow up every three
to four months but this will vary depending on your treatment needs.
How often should I get my eyes 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 are
Age 20-29: individuals of African descent or family history of glaucoma should have an eye exam every 3-5 years. Others should have an exam at least once during this period.
Age 30-39: Individuals of African descent or with family history of glaucoma should have an eye exam every 2-4 years others should have and exam at least twice during this period.
Age 40-64: Every 2-4 years.
Age 64 or older: every 1- 2 years
American Academy of Ophthalmology
National Eye Institute
American Glaucoma Society
US National Library of Medicine
Children’s glaucoma Society
Internet Ophthalmology
Wills Eye Hospital glaucoma service
and foundation
American College of Physicians