Cataract

August 3, 2011

A cataract is a clouding of the eye’s natural lens. Depending on the degree of cloudiness, a cataract can cause a little blur in vision to near total loss of vision. The rate at which a cataract will progress is highly variable. A cataract is not a film over the eye that can be peeled away. A cataract is not visible in the mirror unless it is very dense. Vision can be restored only by surgical removal. Generally, waiting to have a cataract removed will not affect the outcome. A cataract need not be removed, as it is not usually harmful to the eye. The symptoms which patients experience will help to decide whether to proceed with surgery. The term “ripe” is an outdated term. Cataract surgery is necessary when diminished vision interferes with daily living patterns and removing the cataract is worth the rare risks involved.

The majority of cataracts are formed later in life as a part of the aging process. Some patients develop cataracts earlier than others. They are usually not inherited. Cataracts can develop as a result of injury, chronic eye disease, systemic diseases (such as diabetes), and side effects from drugs such as steroids. Exposure to sunlight has been implicated in causing cataracts. Rarely are babies born with cataracts. Cataracts are not caused by reading, watching too much television, sewing, or any other normal activity. Limiting visual activity will not slow down the progression of a cataract. Vitamins and herbal remedies have not been proven to prevent the progression of cataracts.

The only treatment now for cataracts is surgical removal. There are no medications that stop the progression of cataracts. Laser surgery at present is not used to remove cataracts. There are several ways to remove a cataract. in the past, the most common method was the intracapsular procedure, which involves removal of the entire lens and its supporting structures. Today, due to advances in medical instrumentation and surgical technique, an extracapsular cataract extraction is the preferred method in most cases. Through a 3.00to 4.00-mm incision, a cataract is removed by breaking the cataract into pieces with what is called “phacoemulsification” or ultrasonic power and then the cataract is “sucked out.” A cataract is like a grape. A circular opening is made in the front peel of the grape, the contents are sucked out, and the front and back part of the grape will remain. The technique leaves a membrane that helps protect the retina and supports the intraocular lens implant.

Once the natural lens is removed, a new one must replace it to focus the eye and provide clear vision. This can be done in three ways:

  1. Spectacles (glasses) are worn obviously in front of the eye. This is the oldest method, and for quite some time, it was the only method. The glasses required after cataract surgery are thick; they give good central vision but the side vision is compromised. Objects are magnified by 25% which makes it difficult to become accustomed to these glasses. This is a very poor choice and almost never done presently.
  2. Contact lenses are a better method. They can afford good central and side vision. Difficulty arises due to trouble inserting the lens, irritation caused by the lens, and maintenance of the contact lens.
  3. Intraocular lenses are the best method. The lens is placed in the eye in nearly every cataract operation performed today. Excellent results have placed intraocular lenses well beyond the experimental stage. in the last 20 years, over 5 million intraocular implants have been placed in the United States. Under usual conditions, the lens need not be replaced. it does not have to be removed to be cleaned at any time. The intraocular lens affords vision that is the most natural.

Intraocular lenses that we use are placed in one of two locations. Most are placed behind the iris. These are termed posterior chamber lenses. This is the best place for the implanted lens as it is the position where the natural lens existed. The other location is in front of the iris. These are termed anterior chamber lenses. In some patients, this may be the only option if the membranes in the eye are weak.

Intraocular lenses may be inserted after a previous surgery when the patient did not originally have any implant inserted. Many surgeons feel that the placement of a lens as a second procedure is somewhat less satisfactory and more hazardous than placing it at the time of surgery, but many thousands of lens implants have been successfully placed secondarily.

In the “old days,” cataract surgery involved prolonged hospitalization and “sand bags” for immobilization. Many people remember their grandparents undergoing this type of operation and are unnecessarily alarmed about surgery. With modern microsurgical techniques, cataract surgery has become safer and healing more predictable than in the past. The surgery is done on an outpatient basis.

The operation is performed under a local anesthesia, with monitoring of the patient’s heart rate and blood pressure. Depending on the surgeon’s preference, it can be performed with a “block” anesthesia injection around the eye or performed just with topical eyedrop anesthetic agents. This is called topical anesthesia and is becoming more popular. Injection is not required nor is a patch or shield as discharge. Generally, however, the patient will need to wear a protective shield at bedtime.

Patients will probably be examined the day after the surgery. Eyedrops are taken before and after the procedure. Normal daily activities can be resumed the day after surgery. Usually a new glass prescription is required and is given about 3 weeks after the operation.

As in any surgical procedure, an element of risk exists, and complications can occur during surgery or in the healing process in spite of the best of care (occlusion of a blood vessel, retinal detachment, corneal decompensation, macular edema, bleeding, and infection). It may be impossible to predict who may develop a problem.

A rare complication may be dislocation of the intraocular lens implant and it may need to be repositioned. Very rarely the implant may need to be removed. Infection is a very serious complication, which can significantly reduce vision after surgery. To help prevent this, eyelashes are draped and the face and eyes are washed with an antiseptic. Hemorrhage or bleeding is a complication that can range from mild to very serious. The worst bleed is called an expulsive hemorrhage and can leave the eye without vision. The hemorrhage occurs under the retina, away from the cataract operation, and is a random occurrence. Fortunately, this is very rare. A retinal detachment can occur in 1-2% of patients having cataract surgery. If a patient is very nearsighted or myopic, there is a greater risk of developing a retinal detachment. If a detachment is detected early, it can be reattached surgically with usually little vision loss. Macular edema or swelling of the macula (the center of the retina) may occur in 20% of cases. Fortunately, in almost all cases, the fluid is absorbed and good vision returns. Glaucoma may occur after cataract surgery, but usually can be controlled with drops.

During surgery, the membrane that supports the implant may be too weak and part of the cataract may fall back into the eye. This has happened to nearly all cataract surgeons. The best method to handle this complication is usually to have a retinal surgeon remove the piece at a later time.

It should be emphasized that cataract surgery is very safe in the majority of cases. The patient is usually very happy with the results. Future developments will make the operation even safer and more rewarding for both the patient and the surgeon.

SEE ALSO: Aging, Diabetes, Glaucoma

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