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.
Like a laser, the intense cold stimulation to the retina can seal abnormal leaky retinal blood vessels or seal retinal tears. This technique is often preferable to laser in treatment of certain conditions in the far periphery (corners) of the retina, especially when problems such as vitreous hemorrhage or cataract obscure the passage of light into the eye, limiting the effectiveness of laser.
Cryotherapy is often performed in conjunction with surgical treatments for retinal detachment, such as pneumatic retinopexy. It is also sometimes used in the treatment of proliferative diabetic retinopathy, in a manner similar to the technique of panretinal photocoagulation.
Patients usually require small anesthetic injections before cryotherapy is performed. A patch is often applied for the remainder of the day of the treatment, and a short course of eye drops may be required afterwards.