Introduction
Cryotherapy is a minimally invasive procedure in which intense cold temperatures are used to treat various disorders. Cryotherapy is a Greek term in which cryo means cold and therapy is cure. It is also called cryosurgery or cold therapy, wherein liquid nitrogen is mostly used to freeze the tissues at the cellular level. Cryotherapy has been considered a first line of treatment for managing acute injuries for many years. Cryotherapy is more commonly associated with the management of certain skin conditions, bleeding disorders, and different benign and malignant lesions to reduce pain, spasms, and inflammation. However, if necessary, it can also be used in the treatment of certain eye conditions. Cryotherapy is simple, safe, relatively inexpensive, and can be performed quickly in an outpatient setting. Therefore, it is quite popular and commonly used in clinical practice.
What Is Ocular Cryotherapy?
Ocular cryotherapy is an advanced technique in which cold temperatures are employed to treat various disorders of the eye and eyelids. The first ocular cryotherapy was performed by Bietti in 1933, in which a metal probe was cooled in a mixture of acetone and carbon dioxide and applied to the outer wall of the eye to close a hole in the retina. It was later developed by Deutschmann using dry ice probes instead of metal ones. However, these techniques were not adopted until they were developed by Krwawicz in 1961 when a cataract extraction was performed successfully by immersing a metal probe in a mixture of alcohol and solid carbon dioxide. This approach popularized cryotherapy and was adopted by ophthalmologists for different eye problems. Liquid nitrogen is used in cryotherapy for treating skin lesions as its boiling point is the lowest among the available cryogens. However, ophthalmologists primarily use nitrous oxide, or solid carbon dioxide, and freon (a colorless, odorless, noninflammable gas) rather than liquid nitrogen. Therefore, the practice of ocular cryotherapy depends on the trained ophthalmologist and the properties of cryogens used in the technique.
What Are the Indications of Ocular Cryotherapy?
Some of the eye conditions in which ocular cryotherapy is used include:
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Retinal Tears: A tear or a hole in the retina can occur due to aging or following an eye injury or eye surgery. If left untreated, it can lead to retinal detachment and blindness.
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Retinal Detachment: It is an eye problem in which the retina pulls away from its normal position. It is mainly caused due to injury or aging.
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Glaucoma: It is a disorder characterized by the accumulation of fluid, which causes an increase in the pressure inside the eyes. This condition can also damage the optic nerve and lead to blindness or permanent loss of vision.
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Trichiasis: It is the inward growth of eyelashes that may arise due to constant rubbing, aging, infection, or injury to the eyes.
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Retinoblastoma: I1212t is a rare type of eye cancer that affects the retina and is mainly seen in children.
How Is Ocular Cryotherapy Performed?
Cryotherapy is based on the response of the tissues that occurs due to the induction of subfreezing temperatures. Exposure to extremely cold temperatures leads to ice formation within the cells, extracellular fluid, and small blood vessels, thus interrupting the blood supply to the adjacent tissues. This destroys the tissues through ischemia ( loss of blood supply) and necrosis (cell death), inducing inflammation as a cellular response. Ocular cryotherapy requires a cryo console, a cryoprobe of appropriate size connected to the cryo console by insulated tubing, anesthetic medication, cryogen, an indirect ophthalmoscope, and a condensing lens for retinal cases. The cryo console is connected to an electric source and is responsible for controlling the rapid cooling and thawing required during the procedure. Except for cataract extraction, ocular cryotherapy is used only as a surface technique without any incisions into the tissue. The procedure is precise and targets only the affected tissues, thus minimizing damage to the healthy surrounding areas.
Cryotherapy is a simple and outpatient procedure usually performed in a clinical setting. A complete medical history of the patient is taken by the healthcare professional before starting the treatment. A topical anesthetic is applied, followed by a subconjunctival injection of the local anesthetic to numb the eye. An instrument called a cryoprobe is inserted through the outer surface of the eyes that directs the cryoprobe to the affected area. It is followed by several bursts of cold gas, which freezes the targeted tissues. This results in the formation of ice crystals, which destroy the damaged cells. The scar tissue created by the procedure will gradually heal and reattach the retinal layers. Patients will remain awake throughout the procedure but do not experience any pain. However, there may be a cold sensation that resolves quickly. The eye is then patched for a couple of hours.
What Are the Complications of Ocular Cryotherapy?
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Complications may occur during ocular cryotherapy due to over-freezing or the inexperience of the healthcare professional. Early diagnosis and treatment of the condition provide effective outcomes and improve vision. However, some patients may require more than one ocular cryotherapy to repair the damage.
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Ocular cryotherapy may also be associated with side effects such as dryness of the eyes, sensitivity to light, and depigmentation in some patients. Further treatment may be required in case of severe redness, swelling, worsening pain, or vision changes.
What Are the Precautions to Be Followed After Ocular Cryotherapy?
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After the procedure, there may be swelling, redness, blurred vision, and mild discomfort. This can be managed by nonsteroidal anti-inflammatory drugs (NSAIDs) like Acetaminophen, eyedrops, or ointments.
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A cold compress can also be applied over the eyelids to relieve the pain and discomfort.
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Healing usually takes around ten to 14 days. Hence, physical activities must be minimized for a few days, and eye-protective glasses must be used, especially while outdoors.
Conclusion
Cryotherapy is one of the most effective tools employed in ophthalmology to treat various eye conditions. The primary goal of ocular cryotherapy is to stabilize and reattach the tissues, thus preventing loss of vision. It has excellent value in the management of trichiasis, glaucoma, conjunctival dysplasia, retinal detachment, etc. It is preferred to other therapies as the patients respond well to treatment, it is painless, less invasive, and is associated with minimal postoperative adverse effects or long-term complications. However, it is always recommended to consult an expert ophthalmologist and understand the techniques of treatment before undergoing any procedures.
