PubMed · 617700
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1977. [Forum: prostatic cryotherapy].. https://pubmed.ncbi.nlm.nih.gov/617700/
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We examined modifications in the conventional techniques of cryosurgery for reducing the relatively large number of recurrences after hepatic cryosurgery. Since recurrences are likely to develop in tumor regions which are not frozen to lethal temperatures, the temperature distribution in frozen livers was studied by thermocouple techniques and by calculating the spatial and temporal alterations in the thermal fields for detecting, if present, nonlethally frozen sectors in a frozen tumor tissue. Misplacement of the cryoprobes and the presence of blood vessels in the vicinity of the target tissue were found to be the main sources for nonoptimal freezing of the tumor. Furthermore an overestimation of the size of the lethally frozen tumor regions is possible because of the slow fusion and long-lasting shape alterations in the lethally frozen regions growing together from several cryoprobes. The placement of cryoprobe was optimized by aiming for positions of the cryoprobes by which the tumor is totally enclosed by the calculated -50 degrees C isotherm. The effect of blood vessels could be compensated by thermally shielding the target tissue with an additional cryoprobe between tumor and vessel. In irregularly shaped tumors the placement of cryoprobes was improved by calculating the temperature distribution for cryoprobes in positions thought to be optimal and examining whether this selected placement of cryoprobes cooled all regions of the tumor to lethal temperatures. This procedure was performed before actual cryosurgery on a digitized image of the tumor displayed on the PC screen, and, if required, positions of the cryoprobes were altered until calculations showed that all of the target tissue was frozen to lethal temperatures. For small tumors the placement of the cryoprobes outside the target was found to be advantageous. Under such conditions the tumor was so rapidly cooled to lethal temperatures by synergistic effects between the cryoprobes that excessive cryodamage in normal liver tissue was avoided.
PURPOSE: To review the methods and results of management in a large series of patients with Coats disease, to determine risk factors for poor visual outcome and enucleation, and to propose a practical classification of Coats disease. METHODS: In a retrospective consecutive series in 150 patients, Coats disease was defined as idiopathic retinal telangiectasia with intraretinal or subretinal exudation without appreciable signs of retinal or vitreal traction. We reviewed our experience with management, including observation, laser photocoagulation, cryotherapy, and various techniques of retinal detachment surgery and enucleation. The anatomic outcome, complications of treatment, visual results, and reasons for enucleation were tabulated. Factors predictive of poor visual outcome (20/200 or worse) and enucleation were determined using Cox proportional hazards regression models. Based on these observations, a staging classification of Coats disease, applicable to treatment selection and ocular prognosis, is proposed. RESULTS: In 117 patients (124 eyes) with a mean follow up of 55 months (range, 6 months to 25 years) primary management was observation in 22 eyes (18%), cryotherapy in 52 (42%), laser photocoagulation in 16 (13%), various methods of retinal detachment surgery in 20 (17%), and enucleation in 14 (11%). Anatomic improvement or stability was achieved in 76% of eyes, and final visual acuity was 20/50 or better in 17 eyes (14%), 20/60 to 20/100 in eight (6%), 20/200 to finger counting in 30 (24%), and hand motion to no light perception in 49 (40%) Enucleation was ultimately necessary in 20 eyes (16%). Risk factors predictive of poor visual outcome (20/200 or worse) included postequatorial (P =.01), diffuse (P =.01), or superior (P =.04) location of the telangiectasias and exudation, failed resolution of subretinal fluid after treatment (P =.02), and presence of retinal macrocysts (P =.02). The main risk factors for enucleation were elevated intraocular pressure (greater than 22 mm Hg; P less than or equal to.001) and iris neovascularization (P less than or equal to.001). Coats disease was classified into stage 1, telangiectasia only; stage 2, telangiectasia and exudation (2A, extrafoveal exudation; 2B, foveal exudation) stage 3, exudative retinal detachment (3A, subtotal; 3B, total); stage 4, total detachment and secondary glaucoma; and stage 5, advanced end-stage disease. Poor visual outcome (20/200 or worse) was found in 0% of eyes with stage 1, 53% with stage 2, 74% with stage 3, and 100% of stages 4 and 5 Coats disease. Enucleation was ultimately necessary in 0% of stages 1 and 2, 7% of stage 3, 78% of stage 4, and 0% of stage 5 disease. CONCLUSIONS: Carefully selected treatment can anatomically stabilize or improve the eye with Coats disease in 76% of eyes. However, poor visual outcome of 20/200 or worse commonly results. Patients who present with stages 1 to 3 Coats disease have the best visual prognosis, and patients with stages 4 and 5 have a poor visual prognosis.
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