Changeability Test of Aqueous Outflow Resistance: A Tonographic Study of Normal and Glaucomatous Eyes Effect of Ganglionic Blocking Agents Analysis of Initial Part of Tonographic Tracing

IN recent investigations a regulation of the resistance to aqueous outflow has been demonstrated. Important experiments by B arany (1954, 1955, 1956), Bairainy and Scotchbrook (1954), and BarAny' and Woodin (1955) showed various factors causing a change in the resistance to aqueous outflow in enucleated eyes from different species of animals. The enzyme hyaluronidase caused the resistance to aqueous outflow to fall to about 50 per cent. of the initial value. Various influences in vivo were shown to produce changes in outflow resistance, which were not due to a regulation by means of hyalu- ronic acid. An increase in resistance was observed after ligation of the common carotid artery. A decrease was demonstrated after elevation of the episcleral venous pressure by obstruction of the venous circulation. Injection of an extremely pure preparation of hyaluronidase into the anterior chamber in vivo produced an increase of the hyaluronidase-insensitive part of the outflow resistance. This increase could be partly prevented by giving the animals a ganglionic blocking agent, showing thereby the participation of the autonomic nervous system in the regulation of outflow resistance.