Abstract
Purpose:
To determine the range and relative location of gaze angles used during four common visual tasks: computer reading, computer analysis, newspaper reading and walking in an office environment.
Methods:
A head-mounted eye tracking instrument (Mobile Eye, Applied Science Laboratories) was used to track the position of fixation of the right eye at a sampling rate of 30 Hz during four visual tasks. A grid of visual targets at known eccentricities was used to calibrate the instrument and determine the horizontal and vertical angles of gaze (relative to head position) from the acquired fixation data. Subjects performed the following four tasks for approximately 5 minutes per task; desktop computer reading, desktop computer analysis using image processing software, reading a newspaper on a desk, and walking in an office environment. Four subjects completed all four tasks, and two additional subjects completed two tasks only.
Results:
Mean vertical angle of gaze (MVG) for all subjects was most negative (i.e. furthest in downgaze) for the newspaper reading task (MVG = -30.9 ± 4.6°), followed by the computer reading task (MVG = -20.5 ± 3.7°), walking (MVG = -16.3 ± 4.4°) and computer analysis (MVG = -13.6 ± 4.0°). Mean horizontal angle of gaze (MHG) for all subjects was similar for both computer reading and analysis tasks (MHG = -1.7 ± 3.5° and -1.4 ± 2.6° respectively) and newspaper reading (MHG = -2.0 ± 1.0°), with all three of these tasks showing a slight leftward bias relative to the walking task (MHG = 0.1 ± 1.2°). The walking task showed the greatest range of gaze positions in both horizontal and vertical directions. For those subjects who completed all tasks, after combining data for all tasks the interdecile range (IDR, difference between 90th and 10th percentile) ranged from 11.4° to 16.3° horizontally and 21.6° to 24.0° vertically.
Conclusions:
Angle of gaze was successfully tracked using a head-mounted instrument during four common visual tasks. These results are of importance in determining the position of the eyes or line of sight with respect to various forms of optical correction of refractive error.
Keywords: 524 eye movements: recording techniques •
672 reading •
522 eye movements