Glaucoma is a complex disease condition in which the Ocular Pressure (IOP), which may or may not be raised, begins to damage the optic nerve, resulting in typical visual field changes (defects) which if left untreated can lead to blindness.
Glaucoma is a silent disease, having no symptoms of pain etc., until it is very advanced. Unfortunately, visual loss due to glaucoma is irreversible; hence early detection is the key to preventing damage to sight.
Glaucoma tends to have a genetic predisposition hence if there is a positive family history of glaucoma, routine screening must be done of family members to detect early disease.
This is the most common form of glaucoma in the United States. It occurs as a result of aging, the drainage angle of the eye becomes less efficient with time, and pressure within the eye gradually increases.
If the increases pressure results in optic nerve damage, it is known as chronic open- angle glaucoma. Over 90% of adult glaucoma patients have this type of glaucoma.
Chronic open-angle glaucoma damages vision so gradually and painlessly that you are not aware of trouble until the optic nerve has been extensively compromised.
Sometimes the drainage angle of the eye may become completely blocked.
It is as though a sheet of paper floating near a drain suddenly drops over the opening and blocks the flow out of the sink. In the eye, the iris (the part that makes eyes blue or brown) may act like the sheet of paper closing off the drainage angle.
When eye pressure builds up suddenly, it is call acute angle-closure glaucoma.
Symptoms may include:
- Blurred vision
- Severe eye pain
- Rainbow haloes around lights
- Nausea and vomiting
If you have any of these symptoms, call your ophthalmologist immediately. This is an emergency situation for the eye and requires urgent treatment. A cure angle closure glaucoma is more common in Asian people than in people of European descent; it is rare in people of African descent.
In some patients glaucoma has features of both the chronic open angle type and the acute angle closure type. This may be called chronic angle closure glaucoma or mixed mechanism glaucoma. It occurs more frequently in people of African and Asian descent.
Regular eye examinations by your ophthalmologist are the best way to detect early glaucoma.
During a complete and painless examination, you ophthalmologist will:
- Measure your intraocular pressure (tonometry)
- Inspect the drainage angle of your eye (gonioscopy)
- Evaluate any optic nerve damage (ophthalmoscopy)
- Test the visual field of each eye (perimetry)
- Measures the retinal nerve fiber laser thickness (Optical Coherence Tomogrphy - OCT)
Some of these tests may not be necessary for every person. Alternatively, you may need to repeat these tests on a regular basis, to increasing over time.
As a rule, damage caused by glaucoma cannot be reversed. Eye drops, pills and laser and surgical operations are used to monitor progression of the disease.
With any type of glaucoma, periodic examinations are very important to prevent vision loss. Because glaucoma can worsen without your being aware of it, regular follow up is essential.
Glaucoma is usually controlled with eye drops taken several times a day, sometimes in combinations with pills. These medications decrease eye pressure, either by slowing the production of aqueous fluid s within the eye or by improving the flow through the drainage channels.
For these medications to work, your must take them regularly and continuously. It is also important to tell all of your doctors about the eye medications you are using.
Glaucoma medications can have side effects. You should notify your ophthalmologist immediately if you think you may be experiencing side erects.
Some eye drops may cause:
- A stinging sensation
- Red eyes
- Changes in pulse and heartbeat
- Changes in energy level
- Changes in breathing (especially with asthma or emphysema)
- Blurred vision.
Pills sometimes causes:
- Tingling of fingers and toes
- Loss of appetite
- Bowel irregularities
- Kidney stones
- Anemia or easy bleeding
Laser surgery treatments may be effective for different types of glaucoma. The laser is usually used in one of two ways.
In open-angle glaucoma, the drain itself is treated. The laser is used to modify the drain (trabeculosplasty) to help control eye pressure.
In angle-closure glaucoma, the lasers create a hole in the iris (iridotomy) to improve the flow of aqueous fluid to the drain.
When operative surgery is needed to control glaucoma, your ophthalmologist uses miniature instruments to create new drainage channel for the aqueous fluid to leave the eye. The new channel helps to lower the pressure.
Though serious complications of modern glaucoma surgery are rare, they can occur, as with any surgery. Surgery is recommended if your ophthalmologist feels that it is safer to operate than to allow optic nerve damage to continue.
Some complicated cases or advanced glaucoma patients require special valve surgery for control of the eye pressure.