In their hospital, the investigators will study the following alternatives for the anesthetic surveillance of the 3 operating rooms where surgery of the ocular anterior segment is performed: 1) the usual procedure, with the presence of 3 anesthetic nurses (1 in each operating room) and 2) a new organization with an anesthetic nurse checking a centralised monitoring station and a back-up anesthetic nurse ready to intervene inside the 3 operating rooms whenever needed.