Healthy Living Newsletter
Glaucoma... When it’s an Emergency
 When Marcia walked into the dark room, she first thought she had been struck by a sharp object hurled at her. She felt a pain in her left eye so severe and unremitting that it made her vomit.
Glaucoma is the second leading cause of blindness worldwide. In its most common form — open angle glaucoma — it has become known as the “sneak thief of sight” because it often goes undetected until the optic nerve has been seriously damaged.
Marcia’s problem, known as narrow angle glaucoma, was another matter. With this form of glaucoma, symptoms typically come on suddenly and with a severity that leaves no question that it’s a medical emergency. Marcia’s eyesight in the effected eye was saved only by quick treatment.
Narrow angle glaucoma is relatively rare, representing only about 10 percent of glaucoma cases in the United States. It is more common among persons age 60 and over and farsighted persons of any age. Among Caucasians, women are three times more likely than men to be effected.
Narrow angle glaucoma can be caused by a tumor, trauma or eye disease, but, in most cases, the size of the anterior chamber of the eye is a crucial factor. With aging, the lens of the eye gets larger, leaving less room in this part of the eye. Asians and Inuit Indians (Eskimos) have a higher incidence, presumably because of the structure of their eyes. In some cases, diabetic complications may also be a factor.
Pressure Inside the Eye
Glaucoma is a group of diseases with one common feature–damage to the optic nerve, a bundle of fibers at the back of the eye responsible for transmitting images from the retina to the brain.
In most (though not all) cases, the damage is caused by increased pressure within the eye (intraocular pressure).
Narrow angle refers to a narrowing or blockage at an angle. In open angle glaucoma, the angle remains open but drainage is slowed for another reason, causing a gradual buildup of pressure.
Whether rapid or gradual, this pressure can damage the optic nerve, and the result is the development of blind spots in the field of vision. With open angle glaucoma, these blind spots are likely to show up first in your peripheral vision where you may not notice them. And by the time the damage starts to interfere with what you’re trying to read or look directly at, it may be too late to preserve vision.
To detect glaucoma early, doctors recommend regular eye examinations–every two to four years after age 30 and every year or two after age 65. When your eyes are numb, the eye doctor uses a small flat-tipped instrument to push lightly against your eyeball and measure the amount of force needed to indent the cornea (or front covering) of your eye. The doctor will also look inside your eye to examine the fibers of the optic nerve.
Narrow angle glaucoma can also develop gradually, and a test (gonioscopy) allows a doctor to look inside the eye from different perspectives and inspect the drainage angle.
The ideal, of course, is to detect the narrowed angle before it becomes an emergency. In such cases, medications might be prescribed and the patient’s eyes monitored closely. A preventive laser procedure might even be performed to widen the angle.
An emergency blockage occurs when the iris becomes forced up against the meshwork, completely blocking drainage of the aqueous humor. This may happen in response to dilation of the pupils which in turn can be a response to stress, excitement or merely walking into a darkened room. Pupils can also be dilated by certain medications, such as eye drops, cold remedies and patches to prevent sea sickness.
The initial symptom may be the appearance of haloes around lights, but more severe symptoms can develop very quickly: severe eye pain, headache, blurry vision, inflamed eyes, nausea and vomiting. Without emergency treatment, permanent blindness can occur.
The remedy for an acute attack is usually a surgical procedure known as iridotomy.
It’s a simple, non-invasive procedure that can be performed in a doctor’s office. Except for a sensation of heat, the patient experiences no pain or discomfort, and recovery is usually uneventful. Because the likelihood is high of another emergency attack, an iridotomy is usually performed on the other eye at a later time.
Persons undergoing iridotomy have an increased risk of developing cataracts, however, so preventive use of this procedure must be undertaken with caution.
In some cases, another surgical procedure–laser iridoplasty–may be needed in place of or in addition to iridotomy.
Glaucoma is responsible for six million cases of blindness worldwide, and about half of these can be attributed to the relatively rare narrow angle glaucoma.
Open angle glaucoma requires constant vigilance to prevent the gradual but relentless loss of sight. When narrow angle glaucoma strikes as an emergency, it’s usually impossible to ignore. But with prompt action, sight can be saved.
|
