Correction of eye rotations around the optical axis – the 5th dimension of eye movements

Key Points

We started work with the Schwind Amaris in 2008 and achieved excellent clinical results after LASIK without using any new nomograms. Our two surgeons working on the laser had the same good results without using their own nomograms. We then progressed to using the laser's new integrated tools. We were particularly interested in the new Statistic Cyclotorsion Correction (SCC). Our results were presented at the Congress of the German ophthalmic surgeons (DOC 2009) and ESCRS 2009 in Barcelona.

Background to the eyetracking system

The eyetracker compares a reference picture of the patient's eye in the lying position in comparison to the upright position during the examination to estimate the cyclotorsional offset. The resulting angle is automatically used for the correction of the ablation profile. During the measurement the treatment assistant manager on the display is very easy to handle. If the measured torsion angle is smaller than or equal to ±5° the measurment is accepted. If the measured torsion angle is larger than ±5° it is recommended that the surgeon repeat the measurement for safety reasons. The cross check of the measurments shows a high repeatability. This is confirmed by other authors (e.g., C. Arbaleaz, Three-month experience in customised Advanced Cyclotorsion Correction (ACC) with the SCHWIND AMARIS Total-Tech Laser).

As an option the control of the z-axis is also possible. This means, for example, compensation of the movement of the eye when the patient firmly presses their head backwards.