Abstract: By properly shaping the prisms of a Goldmann tonometer head, it becomes possible to accurately repeat two different pressure measurements with two different radii of the flattened corneal surface. From these two different measurements, with a method according to the present disclosure it is possible to obtain the value of the “true” intraocular pressure of a patient and therefore to correct the classic pressure measurement taken with the Goldmann tonometer. Furthermore, by knowing the central corneal thickness with any pachymeter and an average radius of curvature at the corneal apex with any keratometer, with another method according to the present disclosure it is possible to calculate in vivo the modulus of elasticity of the cornea of a patient using the two different pressure measurements.