REPLACEABLE PRISM FOR APPLANATION TONOMETER

摘要

A tonometer (70, 80, 90), preferably for a single use, has an applanation surface (12), an input port (15) arranged to transmit incoming light into the prism, and an output port (16) arranged to transmit outgoing light from the prism. Light entering the input port is directed in an unreflected straight path through the prism to an internal face of the applanation surface. Light internally reflected from the applanation surface proceeds in an unreflected straight path through the prism to the output port.