Glaucoma – The Sneak Thief of Sight
06 Oct 2002
The statistics are frightening. Three million North Americans suffer from glaucoma. The National Eye Institute estimates that 120,000 are blind because of this disease. And half the people with glaucoma do not know they have it. Glaucoma is also the leading cause of blindness in African-Americans and the second leading cause of blindness in North Americans.
The underlying cause of glaucoma is not known. For years doctors believed the primary problem was increased pressure within the eye. And that this pressure suddenly or slowly destroyed the optic nerve that carries images to the brain. However, 20 percent of patients with glaucoma have normal eye pressures yet the nerve cells still die.
Dr. Martin B. Waxman is Professor of Ophthalmologist at Washington University in St. Louis. He says, ” For 170 years, ophthalmologists have treated glaucoma with good success by lowering fluid pressure in the eye.”
Fluid is continually forced into the eye to nourish the lens and other structures. It normally dribbles out of the eye at a controlled rate through a narrow channel.
But with increasing age this control valve has an increased chance of becoming plugged. This increases the pressure within the eyeball , squeezes blood vessels, decreasing nutrition to the retina and optic nerve.
Increased pressure initially damages peripheral vision causing the optic nerve to send smaller and smaller images to the brain. Eventually all peripheral vision is lost leaving patients with “tunnel vision”. Patients now see things as if they were looking through a telescope. If treatment is still delayed central vision will also so be destroyed.
Glaucoma strikes in several ways. Children are sometimes born with a structural defect of the eye. Others develop glaucoma because of injury, infection, cataracts and the use of drugs to treat hypertension or medication such as cortisone.
The late Sir Duke-Elder, an internationally renowned London, England, ophthalmologist, claimed that glaucoma often strikes highly strung and anxious patients. Another English physician noted that glaucoma increased in residents of the Channel Islands after they were occupied by the Germans.
If there is a family history of glaucoma relatives are five times more likely to develop this disease. And African Americans are four times more likely to suffer from glaucoma and six times more likely to go blind from it. The disease also develops at an earlier age in blacks and progresses more rapidly. It’s estimated that 12 percent of African-Americans age 70 and older suffer from glaucoma.
10 percent of victims are struck by acute glaucoma. It’s a major emergency and left untreated it can destroy sight within 24 hours.
Some people make a horrendous error. They believe the intense pain. blurring of vision and redness is due to conjunctivitis (red eye). But severe pain and visual changes are not present in pink eye. So it’s imperative to seek immediate medical attention.
90 percent of glaucoma is due to the chronic type. A few patients will have warning symptoms such as seeing coloured rings around lights, difficulty adjusting to darkened rooms, blurring of vision or failure of new glasses to improve vision. But unfortunately most people are unaware of glaucoma’s presence. And it’s possible to go blind in one eye before glaucoma is diagnosed.
The best defense against what’s been called “The Sneak Thief of Sight” is to have regular eye examinations and a painless one minute test. A small instrument is placed against the front of the eye to determine its pressure and diagnoses the disease in 75 percent of cases. The optic nerve must also be examined for evidence of damage.
When glaucoma is diagnosed eye drops are prescribed to decrease the pressure. Some drops reduce the production of fluid. Others help to facilitate drainage.
Several operative procedures are used to improve fluid drainage. They all involve cutting a tiny opening in the front of the eye to establish a new drainage site for the fluid. Surgeons can also implant a glaucoma valve which helps to keep the hole from healing shut.
In Laser surgery, a narrow beam of light is used to burn the obstructed area. This produces holes which improves drainage. The effects of laser may last only a few years but the procedure can be repeated in some patients.
Surgery and laser procedures are normally reserved for patients where medication has failed.
