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February 1963

Rhythmic Changes in Intraocular Pressure Due to Periodic Changes in Vasomotor Tone

Author Affiliations

From the Departments of Ophthalmology and Physiology, Graduate School of Medicine of the University of Pennsylvania.

Arch Ophthalmol. 1963;69(2):231-235. doi:10.1001/archopht.1963.00960040237015

Introduction  During the course of an investigation, in which intraocular pressure measurements were made directly with highly sensitive pressure transducers, we observed slow rhythmic changes in intraocular pressure, which are simlilar to those which have been observed during tonographic measurements by others.2,7,8,10 In this communication we will describe these rhythmic changes in intraocular pressure, speculate upon their origin, and discuss their possible significance. For reasons given in the discussion we attribute these slow rhythmic changes in intraocular pressure to variations in blood vessel tone.

Materials and Methods  Male and female cats (2 to 3.5 kg.) were anesthetized with pentobarbital sodium (36 mg. per kilogram) intraperitoneally. A 2-way respiratory valve was inserted into the trachea and connected to a modified Donald-Christie apparatus,4 in which the pressure changes were recorded by a pressure transducer (Statham P23BC) and converted to respiratory tidal volume. Heparinized polyethylene tubing was inserted into one femoral

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