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Local tissue oxygen pressure was measured with micro-Pt-electrodes in the resting tibialis anterior muscles of 10 patients with chronic occlusive arterial disease and in 9 healthy subjects. The mean pO2 values in the patient group was 13.3 +/- 5.4 Torr, and 27.2 +/- 4.4 Torr in the control group. The difference is highly statistically significant. Preliminary results of treatment of 10 patients with the rheologically-active drug Ancrod show a statistically significant increase of oxygen pressure in the ischemic muscle tissue. Measurement of muscle tissue pO2 with microelectrodes seems to be an objective and quantitative method to investigate the oxygen supply to ischemic muscles and to judge the effects of therapeutic measures.

The eye of a 47 year old man with tyrosinase-positive oculocutaneous albinism, photophobia, nystagmus and visual acuity 0, 4-0, 5 was histologically examined after orbital exenteration for neoplasia. Histologic serial sections of the centre of the retina showed a continuous 6-8 cell-layer of ganglion cells, without any suggestion of a foveolar pit. The outer layers of the macular retina were altered secondarily by tumor-impression-folds; they were unremarkable at the periphery as were the acid mucopolysaccharides in the receptor region. Electron microscopy of the uvea and the retinal pigment epithelium showed a normal number of pigment granules but a deficiency of melanin, as well as structural anomalies. The absence of the foveolar pit and the decrease of visual acuity in tyrosinase-positive albinism is caused by definite morphologic alteration in the arrangement of ganglion cells in the macular region in the sense of a foveolar aplasia. The etiology is discussed. An identic anomaly has been described in aniridia, similar ones in other congenital ocular diseases.

The ultrasonographic findings in 39 cases of malignant melanoma of the choroid has been correlated with histopathological results. Tumors with hemorrhages and/or necrosis showed a lower reflectivity than those with a higher amount of connection tissue. B-scan ultrasonography was found to be reliable for the measurement of the extent of the tumor in all three dimensions.