[Cyclocryotherapy. Experimental studies of the breakdown of the blood-aqueous barrier and analysis of a long term follow-up study (author's transl)].

We report on experimental results concerning the breakdown of the blood-aqueous barrier following cyclocryotherapy (CTh). The various factors (tip of the cryoprobe, simple or repeated application, pretreatment with prostaglandin-synthetase inhibitors and with phenylephrine, grade of pigmentation and preoperative inflammation of the anterior uvea) were studied, which influence the immediate increase in intraocular pressure (IOP) and the rise in protein concentrations in aqueous humour after the procedure. Early and late histological findings after CTh. were described. Fifty-two patients (60 eyes) with different types of chronic glaucoma were treated with CTh. and followed up for a period ranging from 7 to 44 months (mean 22.9 months). During this period IOP was maintained under 22 mm Hg in 60% of all cases. Best results were achieved with patients suffering from open-angle glaucoma (75%), worst with juvenile glaucoma (50%). Cryocoagulation of one half of the ciliary body yielded goods results in only 35%, whereas cryotherapy of the second half lead to a decrease in IOP in further 78%. Nine eyes developed persistent hypotony, of these, 2 became phthisical. Factors other than extensive coagulation may also contribute to chronic hypotony. The results of our experimental and clinical observations imply that the treatment schedule (temperature, time and number of applications, dimension of the cryode) chosen for our patients is a comparatively safe procedure with regard to the complications and yields good results as far as the reduction of IOP is concerned.