We show that there was little difference in the average astigmatism induced in three surgical groups (Extracapsular (EC), Phacoemulsification with and without scleral tunnelization) at the last control. An examination of a second group of patients shows a significant reduction in the time necessary for recovering at least 80% of the final visual function and a significant shortening of the time elapsed before the prescription of the glasses in the group of patients operated on using phaco with tunnellization. Just as there is a significant relationship between the post-operative cyclinder and postoperative phase 1, there is also a reduction in, and early and lasting stabilisation of, the cyclinder induced by surgery using small incisions. We show that the technique of vectorial calculation brings into play discontinuous trigonometric functions that require great prudence when interpreting statistics of cylinders induced by surgery.