The optic nerve is a bundle of more than 1 million nerve fibers. It connects the retina, the light-sensitive layer of tissue at the back of the eye, with the brain (see diagram). A healthy optic nerve is necessary for good vision.
How does glaucoma damage the optic nerve?
In many people, increased pressure inside the eye causes glaucoma. In the front of the eye is a space called the anterior chamber. It is between the cornea and the iris. A clear fluid flows continuously in and out of this space and nourishes nearby tissues and helps the eye to maintain its shape.
The fluid leaves the anterior chamber at the angle where the cornea and iris meet (see diagram). When the fluid reaches the angle, it flows through a spongy meshwork, where it drains from the eye through small blood vessels.
In angle closure glaucoma, the fluid at the front of the eye cannot reach the angle and leave the eye because the angle gets blocked by part of the iris. People with this type of glaucoma have a sudden increase in pressure, usually to dangerously high levels.
Symptoms of angle closure glaucoma are not subtle. They include:
- severe pain about the involved eye
- often nausea and vomiting
- redness of the eye
- blurred vision
- mid-dilated pupil often non-reactive to light
- swelling around the eye
This is a medical emergency. The patient needs immediate treatment to improve the flow of fluid and reduce the high eye pressure. Without treatment, the eye can become blind within several hours but may take up to two or more days to suffer permanent damager. Usually, emergency laser surgery by your ophthalmologist can clear the blocked drainage pathway and protect sight before it is lost.
The type of laser surgery performed for angle closure glaucoma is called laser iridectomy. Laser iridectomy creates a small hole in the outer part of the iris to connect the posterior chamber and anterior chamber of the eye. This allows the fluid to pass easily to the anterior chamber and the forwardly bulging iris to fall back, thus opening the angle of the anterior chamber so that drainage of fluid is again possible. In rare cases a laser iridectomy cannot be performed successfully. These patients may have an iridectomy made in the operating room with a scalpel.