Cryotherapy

by Robert B. Welch, M.D., Associate Professor of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland

Cryotherapy is the therapeutic use of cold. The name is derived from the Greek word for cold, kryos. Its use is based upon the principle that extreme cold damages tissue by freezing, thus creating an inflammation that destroys an area and replaces it with a scar. As early as 1918 experiments with cold using carbon dioxide snow had shown that inflammation could be produced in the eye. In 1933 this led Professors Deutschmann and Bietti in Europe to apply this clinically in the treatment of detached retinas, using the scar as a fastener, to "tack" the retina in place. However, since instrumentation for applying cold was crude at that time, cryotherapy was soon abandoned in favor of diathermy (heat) introduced by Professor Weve in the late 1930's.

Interest in cryogenics, however, continued in various fields, and in this country Fay in 1936 attempted to induce low temperatures in the brain to destroy malignant tumors. With continued research in this field Cooper in 1961 was able to report successful cryogenic neurosurgical procedures. With new technology now available to produce instrumentation using liquid nitrogen, carbon dioxide, or freon as the source of the cold (freeze), its use in the treatment of retinal detachments was reborn and soon became the most prevalent form of treatment of the retina.

One of the advantages of cryotherapy was that the cold probe could be applied to the outer wall of the eye and the freeze delivered through the coats of the eye to the retina without significantly damaging those layers (conjunctiva and sclera). Thus retinal tears could now be treated without cutting surgery which made it similar in that respect to photocoagulation (laser surgery). With the realization that freezing destroys tissue, various investigators soon tried this technique on various tumors of the eye with some success in retinoblastoma. However, treatment of von Hippel angiomas was reported to be unsuccessful in cases reported in 1967 and 1968, which led Dr. Shea to state in 1967 that cryotherapy "cannot be used to sclerose vascular lesions such as angiomatosis retinae."1 However, in 1966 I had begun to treat angiomas with cryosurgery using a repetitive freeze-thaw cycle (two or three cycles), based on the observations of Cahan that repetition of the cycles of freezing and thawing is one of the criteria for producing cryonecrosis of tissues.2 The cases treated were those where the angiomas were anterior (in the far periphery of the retina) and they were treated transconjunctivally.3 The angiomas responded favorably, shrinking and being replaced by scar tissue.

Thus I added cryotherapy to the use of laser and diathermy in the treatment of angiomas. The procedure is performed with local anesthesia and the post-operative course is similar to that of laser. I use it predominantly on large anteriorly placed lesions that I feel will not respond well to laser or as a subsequent treatment to an angioma that has not responded well to laser. It is planned to treat all cases on several occasions since overtreatment should be avoided to reduce complications. Whether it be cryo or laser therapy, I always anticipate several treatment sessions. Over the years I have found that this conservative approach has considerably lessened complications from treatment.

1. sclerose as a verb means to cause them to harden; angiomatosis retinae is the Latin name for von Hippel-Lindau in the eye, literally a disease of vascular tumors of the retina. 2. cryonecrosis, causing the cells to die by freezing them. Just as a closed bottle of liquid will burst when frozen, the cell bursts and dies when frozen. 3. transconjunctivally, the probe directs the cold through the conjunctiva to the retinal lesion, without damaging the conjunctiva. See illustration. Excerpted from "Von Hippel-Lindau Disease: The Recognition and Treatment of Early Angiomatosis Retinae and the Use of Cryosurgery as an Adjunct to Therapy," Transactions of the American Ophthalmological Society, 1970 68:367-424.

After the Procedure

Follow carefully the instructions of your physician. Even though you don't feel sick, you have had a surgical procedure, and you have a wound in the back of your eye. It is important not to cause this wound to bleed or enlarge, but to allow it to heal naturally. Pamper yourself for 3-7 days to avoid bleeding. Bleeding in the eye can take months to clear, so an investment of these few days is very important.

• Basically, don't do anything that will cause additional pressure in your eye.
• Don't take aspirin. Tell your ophthalmologist about all your prescription medications.
• Keep your head above your heart, or
• Keep your fanny below your head (squat, don't bend over)
• Take your blood pressure medicine (if any) as prescribed
• No heavy lifting
• No jumping or jarring movements
• Take a mini-vacation from your exercise routine (no jogging, push-ups, tennis, etc.)

[as published in the VHL Family Forum, March 1996]

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