[Autoregulation of the papillary vessels and their behavior as affected by halothane]

Halothane lowers the peripheral vascular resistance and blocks autoregulation in the cerebral vessels. Proceeding from the assumption that the papillary vessels behave in like manner, the authors examined increases in papillary pallor under artificial IOP elevation in anesthetized patients with and without Halothane, using the photopapillometer. This provocation test was conducted in 14 patients, first on one eye under normal (N2O/O2) anesthesia, then on the fellow eye after steady state had been attained with subsequently administered Halothane. By quantifying ocular circulatory conditions, the demonstration of the lowering of peripheral vascular resistance in the papillary vessels under Halothane was convincing; the blockage of autoregulation was less obvious. To explain these results the authors suggest that the two effects are gradual and mutually influential.