The system precision measurement of the video eye tracker and the impact of different infrared intensities on it

Abstract

Background EyeLink 2000 high speed video eye tracker has been used in ophthalmology to evaluate the ocular movement ability.Its systemic precision depends on the performance of the eye tracker, and it is also an essential parameter for the evaluation of the data quality.Therefore, the impact of infrared intensity should be illustrated. Objective This study was to assess the systemic precision of the video eye tracker and evaluate the impact of infrared intensity on the result. Methods The EyeLink 2000 high speed video eye tracker and a pair of artificial eyes were used in this study.Firstly the artificial eyes were fixed to the corresponding position as the real human eyes.Each session of recording was undertaken under the different infrared intensities (100%, 75% and 50%). The sampling frequency of binocular recording was set as 1 000 Hz.Each session was sequentially recorded for 60 seconds.The systemic precision was calculated as the root mean square (RMS) of angular distances between successive data points.The RMS values under the different infrared intensities were compared. Results The highest RMS values were (0.005 01±0.000 20)° under the 100% infrared intensity.As the decline of infrared intensities, RMS values were gradually raised, showing a significant difference among different infrared intensity groups (F=3 791.447, P<0.01). The differences were also significant between different groups (all at P<0.05). Conclusions EyeLink 2 000 video eye tracker has good system precision.The infrared intensity influence the system precision of the video eye tracker. Key words: Eye movements/diagnosis; Infrared rays; Visual perception/physiology; Artificial eyes; Video eye tracker/method