• GLAUCOMA is the leading cause of irreversible blindness As many as half of the individuals with glaucoma, however, may not know that they have the disease. The reason they are unaware is that glaucoma initially causes no symptoms, and the subsequent loss of side vision (peripheral vision) is usually not recognized. Glaucoma is often called "the sneak thief of sight."

RISK FACTORS:

• Age over 45 years
• Family history of glaucoma
• Black racial ancestry
• Diabetes
• History of elevated intraocular pressure
• Nearsightedness (high degree of myopia), which is the inability to see distant objects clearly
• History of injury to the eye
• Use of cortisone (steroids), either in the eye or systemically (orally or injected)
• Farsightedness (Hyperopia), which is seeing distant, objects better than close ones (Farsighted people may have narrow drainage angles, which predispose them to acute [sudden] attacks of angle-closure glaucoma.) in general have no symptoms early in the course of the disease. Visual field loss (side vision loss) is not a symptom until late in the course of the disease. Rarely patients with fluctuating levels of intra-ocular pressure may have haziness of vision and see haloes around lights, especially in the morning.

SYMPTOMS

Acute Angle-closure is often extremely dramatic with the rapid onset of severe eye pain, headache, nausea and vomiting, and visual blurring. Occasionally, the nausea and vomiting exceed the ocular symptoms to the extent that an ocular cause is not contemplated. An eye doctor can usually detect those individuals who are at risk for glaucoma (because of, for example, a narrow drainage angle or increased intraocular pressure) before nerve damage occurs. The doctor also can diagnose patients who already have glaucoma by observing their nerve damage or visual field loss. The following tests, all of which are painless, may be part of this evaluation.

TESTING

• Tonometry determines the pressure in the eye by measuring the tone or firmness of its surface. Several types of tonometers are available for this test, the most common being the applanation tonometer. After the eye has been numbed with anesthetic eye drops, the tonometer's sensor is placed against the front surface of the eye. The firmer the tone of the surface of the eye, the higher the pressure reading.

• Visual Field Testing actually maps the visual fields to detect any early (or late) signs of glaucomatous damage to the optic nerve. This test can be grossly done by having the patient look straight ahead with one eye covered and count the fingers shown by the examiner from the side. More typically, however, visual fields are measured by a computerized assessment. For this procedure, one eye is covered and the patient places his or her chin in a type of bowl. Then, when the patient sees lights of various intensities and at different locations, he or she pushes a button. This process produces a computerized map of the visual field, outlining the areas where the eye can or cannot see.