Cryocoagulation of retinal vessels: an experimental model of intravascular coagulation.

Various amounts of cryothermy were applied to the posterior pole of rabbit eyes to determine changes in retinal tissue and vasculature. Four consecutive freezing and refreezing applications of -60 degrees was the most effective technique for achieving central retinal vessel occlusion. Electron microscopic observations of sequentially sectioned occlusion. Electron microscopic observations of sequentially sectioned occluded vessels showed that the vessels were occluded by a platelet plug distally and packed erythrocytes proximally. Fibrin formation was not found in the occluded retinal vessels but was seen within platelet plugs in choroidal vessels. Because cryocoagulation simulates the normal physiologic means of coagulation more closely than other vessel occluding techniques, cryocoagulation of the primary retinal vessels is suggested as an experimental model for intravascular coagulation.     

Parathyroid adenomas evaluated by Tl-201/Tc-99m pertechnetate subtraction scintigraphy and high-resolution ultrasonography

Thallium-201/technetium-99m pertechnetate subtraction scintigraphy of the parathyroid glands was performed in a prospective study of 33 patients who had undergone bilateral neck exploration for elevated serum calcium and serum parathyroid hormone levels. In 31 cases, the Tl-201/Tc-99m subtraction technique yielded an overall sensitivity of 81%, specificity of 99%, and accuracy of 94% for identifying solitary parathyroid adenomas. Tl-201/Tc-99m subtraction scintigraphy correctly identified 73% of parathyroid adenomas weighing less than 499 mg, 79% of those weighing 500-1,499 mg, and 100% of adenomas weighing more than 1,500 mg. In a subgroup of 24 patients with solitary parathyroid adenomas who underwent both scintigraphy and high-resolution sonography, the sensitivity, specificity, and accuracy of both procedures were similar.     

Vitrectomy in experimental endophthalmitis: Part I-Fungal infection.

In studying the dose-related ocular toxicity of amphotericin B in vitrectomized eyes, up to 5 micrograms/0.1 ml concentration of amphotericin C was nontoxic to the ocular structure when injected in the anterior part of the vitreous cavity. Intravitreal injection of 2.5 micrograms of amphotericin B halted fungal endophthalmitis, which was experimentally induced in rabbit eyes, even after 16 days of infection. Combined treatment of vitrectomy and intravitreal injection of amphotericin B not only cured the fungal endophthalmitis but it also cleared the ocular media from opacities.     

Biopsy of human scleral-chorioretinal tissue.

The usefulness of a technique for scleral-chorioretinal biopsies was evaluated on a human eye destined for enucleation due to a malignant melanoma of the choroid. The operative procedure was without complication. The biopsy specimen was removed and carefully evaluated both by light and electron microscopy. The underlying choroid and retinal tissues were successfully preserved by this technique.