To the Editor.—We read with interest the preliminary study by Sand and colleagues (Arch Surg 110:813, 1975) concerning ocular plethysmodynamography using the Gee modality.
From November 1973 to July 1975, we have performed ocular pneumoplethysmography more than 500 times for evaluation of 300 patients utilizing the Gee modality. The instrumentation was developed from several principles of ocular physiology to evaluate aspects of the brachiocephalic arterial system.
When combined with carotid artery compression, a valuable physiologic index is appreciated. We term this the "collateral hemispheric blood pressure," which is that pressure in the eye on the side of carotid compression. This precisely reflects the collateral blood pressure in the circle of Willis, and that back pressure that may be measured above a clamped carotid at operation. An accurate prediction may therefore be made concerning the adequacy of perfusion to the hemisphere in the individual with a temporarily or permanently occluded
OLLER DW, GEE W. Ocular Pneumoplethysmography. Arch Surg. 1975;110(12):1516. doi:10.1001/archsurg.1975.01360180086021
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