Cryotherapy for Cataracts

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Cryotherapy for Cataracts

Definition
Purpose
Demographics
Description
Diagnosis/Preparation
Aftercare
Risks
Normal results
Alternatives

Definition

Cryosurgery, or cryotherapy, is a technique that destroys abnormal tissue by freezing the cells. Cryotherapy can be used in the treatment of cataracts.

The procedure is used to treat cataracts. A cataract is a form of clouding that develops in the lens of the eye. The crystalline lens consists mainly of protein matter and water. Normally, the protein is packed so as to allow light to pass through the lens. A cataract forms when protein molecules start aggregating and clump together, eventually clouding the lens and blocking light. If left untreated, cataracts may eventually cause blindness. Cryotherapy is performed to remove the clouding protein matter from the lens.

Demographics

According to the National Institutes of Health, more than 50% of people over the age of 80 in the United States have a cataract or have had cataract surgery. Some estimates put this figure at 70% or more. Women are affected by cataracts more often than men. African Americans suffer impaired vision from both cataracts and glaucoma at twice the rate of Caucasian Americans, primarily due to lack of treatment.

Description

Cryotherapy involves the application of a very cold probe to the outside of the eye, which, because of the thin nature of the eye wall (sclera), transmits the freezing temperature to the retina. The intense cold stimulation to the retina can seal abnormal leaky retinal blood vessels. This technique is indicated for the treatment of cataracts that obscure the passage of light into the eye, thus limiting the effectiveness of techniques such as laser therapy.

Cryotherapy uses a cryogenic substance, such as liquid nitrogen, to freeze the cataract. At a temperature of -320°F (-196°C), liquid nitrogen is the coldest cryogenic substance available. The ophthalmologist uses a device to direct a small spray of liquid nitrogen directly onto the cataract. Freezing may last from 5 to 20 seconds, depending on the size of the cataract. A second freeze-thaw cycle may be required. Sometimes, the ophthalmologist will insert a small needle connected to a thermometer to make certain the cataract is cooled to a low enough temperature to guarantee destruction. In another option, liquid nitrogen or another cryogen is circulated through a probe to cool it to low temperatures. The probe is then brought into direct contact with the cataract to freeze it. The freeze time can take two to three times longer than with the spray technique.

Diagnosis/Preparation

In order to see the back of the eye properly, the examining ophthalmologist uses two powerful microscopes, the slit lamp and ophthalmoscope. Eye drops are also often used to make the pupil bigger, so that

KEY TERMS

Extracapsular surgery— A cataract surgical procedure in which an incision is made in the cornea to remove the hard center of the lens. The natural lens is then replaced with an intraocular lens (IOL).

Glaucoma— Eye diseases characterized by an increase in intraocular pressure which causes pathological changes in the optic disk and defects in the field of vision.

Phacoemulsification— A surgical procedure for removal of the crystalline lens in which a needle is inserted through a small incision on the side of the cornea of the eye, allowing the lens contents to fall through the dilated pupil into the anterior chamber where they are broken up by ultrasound and aspirated out of the eye through the incision.

the back of the eye can be seen more clearly. The effect of these drops wears off after a few hours. Once a cataract has been diagnosed and has progressed to the point that it is interfering with daily activities and normal lifestyle, an appointment is made to treat the cataract.

For cryotherapy, the patient may be asked to skip breakfast, depending on the time of surgery. Upon arrival for cryotherapy, he or she is given eye drops, and perhaps medications to help relax. A local or topical anesthetic is used to make the procedure painless. The patient may see light and movement, but will not be able to see the cryotherapy when it is performed. The skin around the eye is thoroughly cleansed, and sterile coverings are placed around the patient’s head.

Aftercare

After cryotherapy, a patch is placed over the operated eye and the patient is asked to rest for a while. The attending physician checks to see if there are any problems, such as bleeding. Most people who have cataract cryotherapy go home the same day. Arrangements for transportation home should be made because individuals cannot drive after cataract surgery. After the procedure, the doctor schedules exams to check the progress of the vision. Eyedrops or pills may be given to help healing and to control pressure inside the eye. The patient is also asked to wear an eye shield or eyeglasses to help protect the eye, and he or she is told to avoid rubbing or pressing on the eye, and to not lift heavy objects because bending increases pressure in the

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?

Cryotherapy can be done in the treating doctor’s office. The doctor is usually an ophthalmologist, specialized in the treatment of cataracts. An ophthalmologist is a physician who specializes in the medical and surgical care of the eyes and visual system and in the prevention of eye disease and injury. He has completed four or more years of college premedical education, four or more years of medical school, one year of internship, and three or more years of specialized medical, surgical, and refractive training and experience in eye care.

eye. Walking, climbing stairs, and light household chores can be performed.

Risks

Narcotic analgesia may be required after the procedure to relieve pain. Cryotherapy also causes significant swelling of the eye and eyelid, which makes postoperative assessment difficult. Problems after cryotherapy are rare, but can occur and may include infection, bleeding, inflammation (pain, redness, swelling), loss of vision, or light flashes. With careful medical attention, these problems usually can be treated successfully.

Normal results

Surgical treatment for cataracts usually results in excellent vision; however, if other problems are present besides the cataract, as, for example, degeneration of the retina or optic nerve, results will not be as favorable.

Alternatives

The alternative treatment for cataracts is surgical cataract removal, which is one of the most common surgical procedures performed in the United States. Approximately 90% of patients who undergo this surgery experience improved vision. Two procedures are commonly used to surgically remove a cataract: phacoemulsification and extracapsular surgery. During phacoemulsification a small cut is made in the cornea, and a probe that emits ultrasonic waves is inserted into the eye. The ultrasonic waves break up the lens, which is then suctioned out of the eye. During extracapsular the doctor makes a larger cut in the eye and removes the majority of the lens in one piece.