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- What is Glaucoma?
- Diagnosing Glaucoma
- What Causes Glaucoma?
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What is Glaucoma?
Glaucoma is one of the leading causes of blindness affecting approximately 2 million people in the USA. Glaucoma refers to a group of eye diseases in which damage is caused to the optic nerve and as a result vision becomes impaired or blindness occurs.
In most cases, this optic nerve damage is caused as a result of increased pressure within the eye although the damage may also be caused by poor blood supply to the vital optic nerve fibers, a weakness in the structure of the nerve, and/or a problem in the health of the nerve fibers themselves. While Glaucoma is serious, if recognized and treated early it can be controlled. This is made difficult since glaucoma symptoms rarely occur until the disease is in a progressed stage.
What are the Different Types of Glaucoma?
- Chronic (primary open-angle) Glaucoma: This is the most common form of Glaucoma which often develops gradually, giving no warning signs until sight is irreversibly compromised. Peripheral vision slowly deteriorates as pressure in the eye builds up, leaving the individual with limited tunnel vision.
- Low-tension or Normal Tension Glaucoma: This type of Glaucoma occurs in the absence of elevated eye pressure. Optic nerve damage occurs, sometimes as a result of low blood pressure and as a result narrowed vision occurs.
- Acute (angle-closure) Glaucoma: When the pressure inside the eye increases rapidly due to the iris blocking the drainage of eye fluid, acute glaucoma can occur. This type of glaucoma is rare and is often severe. Symptoms come on suddenly and include pain, nausea, blurred vision, rainbow effects around lights and redness of the eye. Immediate medical help should be sought. If treatment is delayed there can be permanent visual damage.
- Congenital Glaucoma: Generally seen in infants, this rare form of glaucoma is caused by an abnormal drainage system. It can either be present at birth or develop later on in life. Parents often notice that their child seems sensitive to light, and has slightly enlarged and cloudy eyes that are often teary.
- Secondary Glaucoma: This can occur as a result of other disorders of the eye such as injury, cataracts, eye inflammation, previous surgery, diabetes, tumors, and certain medications such as steroids.
Usually testing is involved to rule out other possibilities. There are a number of tests that can help your doctor or ophthalmologist check for glaucoma.
Tests to Diagnose Glaucoma
- A Visual Acuity Test - This is your average eye test that checks the accuracy of your vision and will probably require you to read a few letters or numbers varying in size.
- A Visual Field Test - This test measures your peripheral or side vision as poor side vision is usually a sign of glaucoma.
- A Pachymetry Test – This test uses numbing eye-drops and an ultrasonic wave instrument to measure the thickness of your cornea.
- An Optic Nerve Check - Done with an ophthalmoscope, this test checks for any damage to the optic nerve.
- An Eye Pressure Check or Tonometry - This measures intraocular pressure and the amount of fluid in the eye.
Symptoms of Glaucoma
Glaucoma symptoms are generally unnoticeable until permanent damage has occurred. Because the damage progresses so slowly, (unless in cases of acute or congenital glaucoma) it usually goes unnoticed as peripheral vision gradually degrades. One eye "covers" for the other, and the person remains unaware of any problem until a large number of nerve fibers have been destroyed, and with them, a large part of visual capacity.
The lack of glaucoma symptoms makes it hard to diagnose the disease in its early stage and therefore glaucoma treatment can be delayed. The individual eventually becomes aware that while objects seen in front may still be seen clearly, objects to the side may be blurred or all together missed. This damage is irreversible and usually progressive, so early identification and treatment is essential.
What Causes Glaucoma?
The eye constantly produces aqueous humor, (the clear fluid that fills the anterior chamber of the eye) and this aqueous is steadily filtered out of the anterior chamber through a complex drainage system.
When the drainage system becomes too slow, or for other reasons, the aqueous builds up in the eye, the eye’s intraocular pressure (IOP) increases and pressure is put on the optic nerve and retinal fibers. This damages these highly sensitive parts of the eye and the result is visual impairment.
While anyone can develop glaucoma, some people do have a higher risk.
Characteristics of Increased Risk of Glaucoma
- a family history of glaucoma
- recurrent migraines
- short sightedness (myopia)
- eye injuries or past eye traumas
- high blood pressure
- past or present use of cortisone drugs (steroids)
In addition, statistics show that African Americans have a markedly higher risk of developing glaucoma, as do people over 60.
Help for Glaucoma
While glaucoma treatment cannot recover what vision has been lost as a result of the disease , it can stop, or at least markedly slow down, the damage process.
Treatments for Glaucoma
The most common form of glaucoma treatment are eye drops that reduce pressure build up in the eye. These are specific to the type and severity of glaucoma and generally need to be taken regularly for best effect. Examples are Timoptic, Xalatan or Alphagan. Oral medication may also be prescribed in some cases. As with all prescription medication, special caution needs to be taken as many have potentially dangerous and bothersome side-effects.
Laser Treatment (laser trabeculoplasty)
Usually recommended when eye drops do not stop deterioration of vision, laser treatment helps to drain excessive fluid from the eye. This is a fairly simple in-clinic procedure where your doctor will numb the eyes with numbing drops and a laser will be used to burn holes through the draining mesh of the eyes. A hospital stay is not necessary after this procedure although the individual should take necessary precautionary measures as eye inflammation is a common side-effect.
Surgery is generally only considered as a last resort once other treatment methods have failed. During surgery, a small piece of tissue is removed from the eye to create a new opening to drain the aqueous fluid and release pressure. Side effects include the development of cataracts, problems with the cornea, damage to the visual fields of the eye and inflammation or infection inside the eye.
More Information on Glaucoma
Tips for Coping with Glaucoma
- Take medication regularly and keep all eye check appointments.
- Make necessary adjustments to your lifestyle in order to manage your condition effectively, but do not limit your life. While it helps to know your personal limits and make changes (such as driving less at night), it is essential to realize that glaucoma doesn’t have to be a life altering diagnosis.
- Increasing the heart rate can help to reduce intraocular pressure so try to get at least 30 minutes of exercise a day.
- Take care of both your emotional and physical health. It’s important to seek emotional support and to ask for help if you need it.
- Wear sunglasses or tinted lenses to help reduce glare and contrast.
- Reduce caffeine as studies have shown that it is linked to increased pressure within the eyes.