Laser And Cryotherapy

“Cryo” refers to “freezing”. Cryotherapy involves placing a very cold metal probe against the wall of the eye so that all of the eye’s layers are frozen, including the retina that lines the inside of the eye.

Cryotherapy creates an adhesive scar that seals the retina against the wall of the eye. The effect of cryotherapy (the adhesive scar) is similar to laser treatment, but the treatment effect is accomplished using cold rather than heat.

Cryotherapy is used most often to treat retinal tears. The retina surrounding the tear is frozen, creating an adhesive scar around the tear that is quite similar to the scar created by a laser. It is used in a similar manner as part of pneumatic retinopexy or scleral buckling for treatment of retinal detachments.

First, the eye is numbed, often with an injection of numbing medicine just beneath the skin-like covering of the eye called the conjunctiva. The patient usually feels nothing during this injection. Occasionally, numbing medicine is injected below the eye, through the skin of the lower eyelid, to numb the entire eye. This method is also basically painless, but the patient often feels pressure. A patch must be worn over the eye for several hours after the procedure if the entire eye is numbed, because the blink reflex is taken away and the surface of the eye could become very dry if it is not patched closed.

After the eye is appropriately numbed, the doctor uses a head light and a lens to look into the eye so the freezing probe can be placed in the correct position, immediately adjacent to the retinal tear. The retina surrounding the tear is frozen, usually with several separate “freezes”.

Since both methods accomplish the same treatment effect, this is largely a matter of personal preference for the doctor and the patient. Both methods take approximately the same amount of time (roughly 15 minutes, depending on the number and size of the tears) and are similarly comfortable. Retinal tears sometimes cause bleeding inside the eye that might block the laser beam from reaching the retina. In such a case, cryotherapy is preferred, as it freezes “from the outside in” and therefore is not impeded by blood inside the eye.