Analysis of Upper Eyelid Saccades by a Computed Imaging System

Abstract

Abstract: : Purpose: To analyze upper eyelid saccades measured with a regular CCD imaging system and a commercial PC. Methods: The system obtains a target signal of the eyelid movement, by focusing an image onto a regular CCD (NTSC video system). The images are acquired and digitized by a PC compatible frame grabber board at a rate of 30 frames per second, and are subsequently analyzed by a software with calculate the position of a blue mark on the eyelid. Measurements of eyelid position during down and upward saccades between the straight-ahead position in the lower and upper visual fields could be easily recorded. The characteristics of the movement determining the trajectory, amplitude, velocity and their relationship were analyzed for 10 normal subjects. Results: Up and downward lid saccades increase linearly for the most part of their trajectory. A transient overshoot was detected for both up and downward lid saccades. The table shows the mean amplitude and velocity values obtained in the lower and upper visual fields. Conclusion: The amplitude and the velocity of the downward upper lid saccades were higher than the upward saccades in both upper and lower hemi-field. These data agree well with other data obtained with magnetic search coil techniques indicating that computed imaging systems can be powerful tools for clinical research on eyelid dynamics. 

Keywords: 410 eyelid • 429 image processing • 406 eye movements