Safety in up to 7 Dimensions
Eye-Tracking in Space und Time
Thomas Magnago, SCHWIND eye-tech-solutions GmbH & Co. KG
Even when our eyes fixate on a certain point, they still move involuntarily approximately 90 microns per millisecond. For successful refractive treatment, the exact centering and consistent positioning of the eye is, therefore, crucial because this provides perfect results at maximum safety.
Seven Dimensions
Seven-dimensional eye-tracking is a highly-developed method and makes Schwind eye-techsolutions’ eye lasers unique, minimizing treatment errors.
In addition to linear eye movements in the first and second dimension, horizontal and vertical rolling movements in the third and fourth dimension can also be determined and compensated.
In the fifth dimension, the eye-tracker compensates torsional differences between the sitting and lying position of the patient, as well as rotating movements of the eye during laser treatment.
The sixth dimension is defined as the z-axis. Here, eye movements originate by upward and downward movements of the head or eyes. The repositioned laser pulses that result from positioning errors along the z-axis are shown in the figure below.
The seventh dimension relates to time. Latency-free tracking provides for the compensation of eye movements that occur in the timeframe from the recording of the eye through the eye-tracker camera to the firing of the subsequent laser pulses. The eye-tracker carries out a movement analysis based on previous eye positions. It calculates where the corneal target position will be for all six positions at the time of the subsequent consecutive pulses. The laser system knows exactly at which point in time and at what position the laser pulses will be released.
The result is ablation without latency time: the perfect combination of speed and precision.
Thomas Magnago is head of customer support at SCHWIND eye-tech-solutions GmbH & Co.KG. This medium-sized, family-run company with more than 100 employees is the world’s technology leader in the area of excimer laser systems for the treatment of ametropia and corneal diseases.
