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.
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 upward on the examinee’s head. This also reduces glare.
If it is still troublesome to calibrate, there is a quick fix. Apply masking tape to the frame of the glasses or tape a piece of paper to the frame as seen below. This reduces glare and allows the EyeTracker to focus on the examinee's eyes.