 Simultaneously, the eye tracker plots the retinal movement during fixation attempt defining the PRL zone as well as fixation stability.Some microperimetry instruments calculate 2 different PRL zones during the examination.To create the fundus image an infrared telecamera is used, as in the case of the "Nidek-MP1", or a Scanning Laser Ophthalmoscope (SLO), as in the case of the "Centervue-MAIA".