[Possibility of surface-independent tonography and tonometry]

A method of simultaneous measurement of intraocular pressure and volume displacement is reported. An electronic pressure sensor (diameter 3 mm) was positioned in the centre of the base of a transparent applanation body (diameter 9 mm). The corneal applanation area could be changed by different applanation forces and was measured photographically. In isolated human and porcine eyes, sensor signal and intraocularly measured pressure were related linearly and independently of the applanation area. In human eyes in situ, the rigidity coefficient decreased with increasing pressure. Adhesive forces and stiffness of the cornea obviously only falsify tonometry at the margin of the applanation area.