When an examinee wears dark-framed glasses, the EyeTracker may occasionally confuse the glare from the glasses or frames for lighter-colored eyes and will focus its infrared beam on the glare instead of the eyes. For example, the image below has red arrows indicating where the EyeTracker catches the glare.
When the EyeTracker cannot maintain focus on the examinee’s eyes, it can make it difficult, and sometimes nearly impossible, to calibrate the Eye Tracker. Also, if this issue causes calibration to be lost during a test, that test will probably not be scored due to insufficient data.
Glare can be caused in part by overhead lights or by the computer monitor. Please ensure the testing room has indirect lighting and avoid placing a light source behind the examinee’s head. Also, it may be necessary to tilt the glasses slightly on the examinee’s head. This also reduces glare.
If you administer an EyeDetect test to a person wearing glasses, here are some solutions:
1) If the examinee has glasses with only one gradient, ask her or him to take off the glasses if possible. Bifocals and trifocals can create problems as well.
2) If it is not posible for the person to read the monitor without glasses, cover the top part of the frame in order to avoid the glare from the light. You can cover the glasses with paper, tape, or Post-it Notes.
3) If the lenses also have problems with the glare, adjust the handles so that the lenses are at the same angle as the Eye Tracker. This can reduce the glare.
Note: Converus is working with the manufacturer of the Eye Tracker to solve the problema. If it cannot be resolved adequately, Converus will propose other solutions, such as using paper glasses to cover frame.