[Cyclocryotherapy in chronic glaucoma].

Abstract

For the last 10 years, cyclocryotherapy has been performed on nearly 700 glaucomatous eyes using practically the same technique. The cyclocryotherapy was standardized: six applications in the lower half of the globe, 4 mm posterior to the limbus as measured from the center of the 2.5 mm diameter cryoprobe. Freezing lasted 60 s; the temperature of the cryoprobe in the air was -65 degrees C and about -55 degrees C during the application. The cryo-induced lesion was found macroscopically, as well as with the microscope, in the pars plana and both epithelial layers were destroyed. The ciliary processes were only slightly affected. Alterations were also seen in the posterior part of Schlemm's canal and in the trabecular meshwork. The trabecular meshwork showed wide intertrabecular spaces. The trabecular lamella were partially interrupted with destroyed cellular elements. Tonographic and fluorophotometric findings showed a transient reduction in the formation of the intraocular fluid in the early postoperative stage. During the same plan there was a considerable breakdown of the blood aqueous barrier. Clinically, one can see a reaction in the anterior chamber with or without fibrinoid exudation. In the late stage, the inflow of the intraocular fluid mostly reached the preoperative level, whereas the outflow improved significantly. Following cyclocryotherapy, a IOP reduction of about 40% was achieved. In 85% of the treated glaucomatous eyes, if was possible to bring the IOP under control. However, in half of these eyes medical therapy was also needed. Cyclocryotherapy represents an alternative to the filtering operation, and it is not necessary to enter the bulb with this procedure.