Glaucoma

Fluid flows in and out of your eye normally. Glaucoma is the condition which occurs when the fluid does not flow; specifically, fluid cannot flow out and the pressure of the liquids in the your increases and puts pressure on the optic nerve. Eventually, glaucoma can cause blindness.

There are three general types of glaucoma:

1) Open-angle glaucoma is the most common normally causes no pain, and has few warning signs. In some cases, pressure is normal, but vision can be lost.

2) Closed-angle glaucoma is an acute rise in eye pressure, and must be lowered immediately to prevent blindness. Severe pain and blurring can accompany an attack. A chronic form of this can occur more slowly and without symptoms.

3) Other forms of glaucoma can be links to injury, inflammation, a cataract, eye tumor, or advanced diabetes.

Glaucoma normally affects those above 50 years of age, but those over 35 should check for this disease once every two years. High-risk groups should have their eyes checked annually. Routine eye exams include a test for glaucoma, but be sure to ask if you think you might be at risk. Though vision loss cannot be restored, lowering eye pressure immediately can save what remains of sight. Treatments can include medication or laser treatment or surgery.


The Mechanics of Eye Drainage

The area of the eye forward of the lens is constantly bathed with a clear fluid called the aqueous humor. It is generated from the ciliary body, located behind the iris, at both the top and bottom of the eye. The aqueous humor is pumped up in front of the lens into the anterior chamber, the space in front of the iris, and drained through the trabecular meshwork, a network of holes surrounding the iris. They are taken into the bloodstream, which carries away wastes collected by the aqueous humor. It is the trabecular meshwork which can clog and forces the pressure in the eye to increase, resulting in glaucoma.

Vision is lost when the optic disc experiences pressure, which kills optic nerve fibers. Peripheral vision is commonly reduced first. As the fibers die, the optic cup enlarges, resulting in more complete vision loss.


Dignosis of Glaucoma

Glaucoma is often hereditary; patients should let the doctor know if any blood relative has suffered glaucoma.

A tonomoter measures the pressure inside they eye. A small plastic prism is pressed to the cornea after anesthetic eyedrops are applied. More commonly, a puff of air will be directed onto the cornea and the tonometer will read the pressure. An ophthalmoscope or fundus photograph are used to monitor changes to the optic nerve, disc, and cup.

The drainage angle between the cornea and iris is measured with a special lens called gonioscope. The lens contains a mirror that allows the doctor to see the angle of drainage.

A perimetry, or visual field test, is performed to determine if peripheral vision has been lost or reduced. A light is shown in a grid pattern, with the patient responding to the light when it flashes. This allows for a field of vision to be mapped; dark areas in a printout indicate reduction of vision.


TREATMENT OPTIONS

Open-angle Glaucoma

The two options in the treatment of glaucoma is to reduce fluid production or to increase drainage rate. Prescription of eyedrops or pills can reduce fluid output; medication, laser treatment, and surgery are the options to re-open the trabecular meshwork.

All glaucoma patients must understand that even with successful treatment, medication must be continued as prescribed to prevent the reoccurrence of glaucoma.

Different kinds of eyedrop medications can be used for decreasing fluid flow (one to two times a day) and for unblocking clogged drainage holes (two to four times a day). Side effects are rare, but some may experience headaches, irritation, or blurry or dimmed vision. Be sure to let your doctor know of any side effect you may experience. (For instructions on how to apply eyedrops, click here.)

Pills to reduce eye fluid production can be used along with eyedrops. Again, most people experience no side effects, but some report tingling in toes or fingers, nausea, drowsiness, loss of appetite, or problems with bowel movements.


Laser Treatment

Trabeculoplasty
If side effects are experienced or if eyedrops or pills are not a viable option, a laser treatment called trabeculoplasty may be done, where holes are open in the trabecular meshwork. Laser energy is used to stretch the tissue, allowing the clogged holes to open.

The eye is prepared for laser treatment with anesthetic eyedrops, and the patient sits at a device that will stabilize the head, keeping it still. Treatment takes a few minutes. Vision may be blurry for a little while, but should return to normal within a few hours.

After laser treatment, your eye pressure will be evaluated. Medication may be necessary to help control eye pressure in the future.


Surgery

Trabeculectomy
An outpatient procedure, a laser is used to drill a hole along the sclera, to bypass the clogged trabecular meshwork.

The patient lies down under a powerful microscope, and the eye is numbed with anesthetic. A piece of the sclera is opened like a flap, and the laser carves the trabeculectomy. The procedure takes about an hour, and the patient may go home soon after; arrangements must be made for someone to help get the patient home.

Medication must be taken and an eye shield or patch be work to keep the eye free of dirt or outside moisture. A check-up could be done later the same day, or the next. The doctor may prescribe medications once the eye heals to control pressure.

Other kinds of glaucoma
When the iris is totally blocking the drain in the eye, this is referred to as closed-angle glaucoma, which is an acute condition that affects one eye at a time. Pressure can rise very fast and vision can be gone within hours, accompanied by severe headaches, eye pain, blurry vision, vomiting, nausea and halos around lights. Since the loss is permanent, emergency treatment is needed.

Partially blocked drains lead to a condition called narrow-angle glaucoma. It is non-acute, tends to happen in both eyes simultaneously, and pressure rise is slower. No pain or other symptoms may be manifested, making this a "silent thief" of eyesight.

The goal of treatment is to first lower pressure to prevent further damage to the optic nerve, then to use laser treatment or surgery to allow the accumulated fluids to drain properly. Medicating the condition can entail using eyedrops every 15 to 30 minutes to stop fluid production, and to allow the iris to be pulled away from the drainage holes. Medicine in pill and intravenous form can also be given.

An iridotomy can be done, where a laser makes a small opening in the iris is made in the top of your eye, below the eyelid. To accomplish this, the eye is numbed with anesthetic, and the patient sits against a chin- and headrest, to keep the eye still. Treatment usually takes a few minutes. The patient can be accompanied home short while later, and can resume a normal routing. Eyedrops are used at first, and eyes are checked for pressure the same day or the next.

As a preventative measure, the doctor may recommend both eyes be treated, to prevent a future acute attack.