A pachymeter apparatus for measuring corneal thickness is configured for the calculation of intraocular pressure ("IOP"). The apparatus includes a pachymeter (12) for measuring corneal thickness as well as a microprocessor (16) and a user interface (22). A reading of IOP from a tonometer can be entered into the device and corrected according to the pachymeter reading of corneal thickness. Correction algorithms are user selectable and user customizable. A pachymeter may have a graphical display (24) which displays multiple locations at which measurements are to be taken. A pachymeter may use a capacitor (52) charged by a variable current supply (54) to measure times for signals to be reflected from a back side of a cornea.
