1. A method of calibrating an ophthalmic lens drilling machine, the drilling machine including a drilling tool, an ophthalmic lens support associated with a first coordinate system, and a programmable guidance unit for guiding the tool, the programmable guidance unit being associated with a second coordinate system expressing command coordinates which define a target drilling point; said method comprising: placing a template on the lens support, the template having pre-applied markings defining a third coordinate system related to the template, said placing being conducted such that the third coordinate system substantially coincides with the first coordinate system; drilling the template in at least one pre-determined point corresponding to the target drilling point defined by predetermined command coordinates so as to create a drilled template, said drilling being performed such that a real drilling point is obtained; creating an image of the drilled template; analyzing the created image using an image analysis unit to measure an offset between the position of the real drilling point and the position of the target drilling point; and introducing a correction of the command coordinates using the guidance unit so as to introduce a correction of the command coordinates capable of compensating for the offset; wherein said drilling comprises drilling the template at two predetermined points, each predetermined point corresponding to a target point defined by predetermined command coordinates, so as to obtain two real drilling points, said introducing a correction comprising determining a correction based on a mean value of the offsets of the positions of the two real drilling points with respect to the respective two target points.