Cataract Surgery and Astigmatism Reduction
Glaucoma is a condition in which the eye pressure is too high and progressive optic nerve damage occurs which can result in permanent visual loss. In the far majority of cases there are no symptoms and damage occurs without the patient being aware. Over 2 million people in this country have glaucoma (half of these patients are not aware they have the disease). A complete eye examination, with an intraocular pressure check and examination of the optic nerve with additional ancillary testing are utilized to diagnosis glaucoma. Most patients are successfully treated with topical medications to lower the eye pressure.
It is not uncommon for patients to have both a visually significant cataract and glaucoma. Both of these conditions are much more common as we age. Occasionally, at the time of microincision cataract surgery, a glaucoma filtering surgery, called a trabeculectomy, is performed as well.
A trabeculectomy creates a valve like drain in the wall of the eye to bypass the clogged natural drain. The surgically created drain functions as a valve and fluid escapes only after the pressure within the eye reaches a certain level.
In the white of the eye (the sclera) a partial thickness flap is created and a small hole is made through the remaining inner half of the sclera. The flap is then sutured back in place covering the inner hole. This creates the valve effect where fluid drains around the outer flap. Postoperatively, it is not unusual to use a laser in the office to cut these sutures to titrate the amount of resistance and lower the ultimate eye pressure. A clear transparent tissue, called the conjunctiva always covers the white of the eye. Fluid escaping through the surgical hole collects beneath this lining. The resulting blister like elevation of the conjunctiva is called the "bleb". The bleb is located beneath the upper lid.
The normal healing process in the body is to heal any hole. In this operation, if the surgical drain heals completely shut then the eye pressure will return to its original high level and the operation will not be successful. To keep the drain from closing off, it is often desirable to delay the normal healing process following glaucoma surgery. Differing healing rates among individual patients adds to the unpredictability of glaucoma surgery.
Commonly at the time of the glaucoma operation an "antimetabolite" is administered to the drainage site on the sclera to decrease the healing process. In addition, after the surgery in the postoperative period additional antimetabolites may be administered via a needle just inside the lower lid.
The microincision cataract surgery and lens implant is usually performed at a separate site from the glaucoma operation. All patients that have glaucoma and need cataract surgery do not necessarily need the glaucoma operation. This decision to combine both operations is based on the severity of your glaucoma, how many medications you are currently using to control your glaucoma and other factors. Dr. Ullman will discuss with you your particular situation. The microincision technique that Dr. Ullman utilizes does not prevent the possibility of glaucoma surgery in the future if this becomes necessary after your cataract surgery.
A trabeculectomy (glaucoma surgery) is not without significant risks. Some of the risks of the trabeculectomy include:
- Excessive scarring and too high of a pressure
- Too much leakage and too low of a pressure (which can result in poor vision and other complications).
- Infection at the time of the surgery or a delayed bleb infection
- Increase in astigmatism
- Bleeding may occur at the time of surgery or after surgery
- Loss of vision
However, glaucoma that is not treated or not controlled can result in permanent blindness. As always, it is important to use good clinical judgment and make an individualized decision based on your particular situation. The risks and benefits of any surgical procedure should be evaluated before any surgical procedure is performed.
