The Basics of Glaucoma

There are two basic types of glaucoma; open-angle and closed or narrow angle glaucoma. Open angle glaucoma is the more common of the two; angle closure glaucoma can result in much more rapid vision loss and thus needs to be treated immediately. While open angle glaucoma can exist for many years lurking in the background, angle closure glaucoma usually presents with a very painful red eye accompanied by blurry vision, extreme pain as well as nausea and vomiting. It is caused by the sudden blockage of fluid circulation in the eye, specifically fluid getting into the “drain” or angle of the eye. This is where the iris (the colored part) meets the cornea (the clear covering in the front). When the angle closes the fluid that the eye naturally produces has nowhere to exit or drain. This causes the pressure in the eye to rise rapidly. Normal eye pressure ranges to about 20 mm Hg but with an attack of glaucoma can go as high as 70 mm Hg. from This rapid rise will often lead to pronounced vision loss in hours to days rather than over months to years as seen in open angle glaucoma.

Prompt treatment for angle closure is a must to avoid total loss of vision. While medications are administered, the mainstay of treatment is with a laser iridotomy to hopefully break the attack. Laser iridotomy is a procedure that makes a small opening in the iris (the colored part of the eye) to relieve increased eye pressure due to angle-closure glaucoma. When the fluid that normally flows in and out of the eye cannot drain through its sponge-like drainage system, called the trabecular meshwork, the pressure in the eye (intraocular pressure) may rise. This rise in pressure could damage the optic nerve and lead to vision loss. The increased pressure may also push the iris forward, which blocks the drainage system completely, much like a stopper in a sink. This may trigger an angle-closure glaucoma attack, which is a medical emergency. A laser iridotomy is necessary when the fluid that drains from the eye is completely blocked. Laser iridotomy creates a new route for fluid to flow from behind the iris to the outflow drain of the eye. A useful way to understand how the iridotomy works is to think of our bathroom sinks at home. If you were to put the drain plug in and leave the water on, eventually the sink will fill. The auxiliary drain in the front of the sink however prevents the water from overflowing onto the floor. The laser iridotomy creates an opening that acts like the auxiliary drain in the bathroom sink.

One important fact is that once you have an attack in 1 eye you are at great risk for an attack in the other eye. We will always perform a preventative laser in the unaffected eye to prevent a future attack. While no procedure is foolproof, the likelihood of an angle closure attack after a successful iridotomy is close to zero. Laser iridotomy is also performed as a preventative treatment in eyes at risk for angle-closure glaucoma.

What can I expect if I have a laser iridotomy?

A laser iridotomy is performed right in our office. A staff member will give you some drops prior to the procedure that will decrease risks of inflammation associated pressure changes and a drop that will make your pupil smaller and thus your iris thinner. This will take about 15 to 20 minutes to work and in some people causes an aching sensation over the brow that goes away shortly. The physician will then give you a numbing drop once you are seated behind the laser. A contact lens is placed on the eye to help more precisely focus the laser. A laser iridotomy takes only a few minutes. You may see a bright light like a photographer’s flash. You may also feel a pinch-like sensation. In general, there are no activity restrictions following the laser treatment, although you should have someone drive you home after the procedure.

Medications that can partially dilate the pupil, such as over-the-counter cold medications and antihistamines, should be avoided until after the laser procedure is performed. The opening made by an iridotomy is about the size of a pinhead. Typically, neither you nor your friends will notice it. It is usually located in the upper part of the iris, which is covered by your upper eyelid.

Loss of vision can be prevented. Laser iridotomy is a safe and effective procedure with very few risks. Although an eye that has suffered an angle-closure glaucoma attack can be treated, the drainage mechanism may never again functions as well and medications may be required for pressure control. The best treatment is to prevent the attack in the first place. While glaucoma treatments cannot restore vision already lost from glaucoma, early detection and treatment of glaucoma offers the best chance of preserving your vision. Our glaucoma fellowship trained ophthalmologist, Dr. Andrew Bainnson is available in our Smithtown, Deer Park and Riverhead offices to examine and determine if you are at risk. While glaucoma cannot be cured it can be controlled especially if caught early. North Shore Eye Care with its 10 convenient offices has the most sophisticated equipment to examine and treat glaucoma. Call today for an appointment.

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