The Technolas 217z system is capable of conventional laser treatment with PlanoScan software as well as wavefront-guided treatment using the Zyoptix system. The laser treatment is delivered with flying spot technology utilizing a 1 or 2 mm beam at 100 Hz. The FDA-approved treatment ranges are listed in Table 6.1. The Technolas 217z laser has Advanced Control Eyetracking (ACE) and iris registration software. The iris registration software ensures that the correct patient and eye are treated. It checks for rotational misalignment between the diagnostic examination (sitting) and laser treatment (supine) and compensates for pupil center shifts between the dilated and undilated examinations. The ACE technology tracks in four dimensions (x, y, and z axis as well as cyclorotation). The active eye tracker consists of an infrared imaging camera system capturing the geometric center of the undilated pupil at a sampling rate of 240 Hz plus a scanning system to respond and compensate for any detected pupil movement within 2.4 ms. The x–y active tracking range is defined as a deviation of 1.5 mm from original fixation. Within this active range, the laser adjusts the excimer pulses to the intended location according to the pupil position. If, however, the eye moves outside this range, the laser will interrupt the treatment. To account for very fast eye movements (e.g., sudden loss of fixation), a dynamic tracking module recognizes the speed of eye movements by calculating positional changes of the center of the pupil between pictures captured by the eye tracker’s video camera system. If the eye speed exceeds a clinically significant value, the eye tracker software simply interrupts the pulsing until the eye stabilizes again. The surgeon defines the treatment center prior to each ablation according to pupil reference, maintaining full visual control throughout the entire treatment. Using the keypad, the surgeon can manually adjust the treatment center at any time; although this is usually unnecessary once the treatment has begun. The dynamic rotational eye tracking system actively tracks and adjusts for cyclorotation during the laser ablation at a sampling rate of 25 Hz within a 15-degree range. The tracker for the z-axis is passive, interrupting the laser treatment if movement during treatment exceeds 0.5 mm from the initial setting.