Abstract
A tonography device, based on the MacKay-Marg tonometer, has been constructed which will applanate the cornea to a preselected area of 5.0 to 6.0 mm diameter and maintain that applanation area. The pressure decrease with time should resemble the pressure decrease following bolus injection of fluid into the eye. In most cases the pressure decreased in a linear slope, abruptly terminating in a pressure plateau. In most cases, the pressure after 4 min of tonography was lower than preliminary Goldmann applanation pressure.