视频眼动仪系统测量的精确度及不同红外照明强度的影响

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

背景目前EyeLink 2000视频眼动仪眼动仪系统已用于临床检测，视频眼动仪系统精确度是衡量眼动仪检测能力的基本参数，但关于视频眼动仪系统精确度的研究目前在中国尚属空白。目的测量视频眼动仪系统精确度，并探讨不同红外照明强度对视频眼动仪系统精确度的影响。方法采用EyeLink2000视频眼动仪对一双人工眼进行检测。将人工眼固定于检测位，在暗室（1 lx室内照明度）下分别于100％、75％、50％红外照明强度下持续记录人工眼的眼动波形，双眼采样频率为1000Hz，每次记录持续60S，以数据点间角距离的均方根值（RMS）计算系统精确度，比较不同红外照明强度下RMS的变化。结果红外照明强度为100％条件下测得眼动仪系统精确度最高，为（0．00501±0．00020）°。随着红外照明强度的下降，测得的RMS值逐渐增加，总体比较差异有统计学意义（F=3791．447，P〈0．01）。组间两两比较差异均有统计学意义（均P〈0．05）。结论EyeLink 2000视频眼动仪在测量眼球运动时具备较高的系统精确度，视频眼动仪红外照明强度可影响其系统精确度。

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.