FAQ: Can the EyeLink systems be used with participants who are wearing glasses?
While some adjustments may be required, glasses should not present any issue. The lenses of the glasses can reflect the IR illumination back into the camera, which appears as glare. If this glare occurs near or in front of the Pupil and / or Corneal Reflection, it can disrupt tracking. With the Desktop mount in Head-Stabilized mode, this can usually be avoided by having the participant tilt their head up or down a little, thus changing the angle of the glasses so reflection shifts away from the Pupil / Corneal Reflection. If using the SR Research Head Support, the chinpad can move forward and backward by loosening the Chinpad Position Knob at the bottom of the chinrest, so the participant can tilt their head up or down as necessary and still remain comfortable. 


If using the Tower mount, in addition to moving the chinpad back and forth, you can also adjust the angle of the hot mirror by loosening the two knobs at the front of the mirror assembly.


With some glasses, it's possible that the eye tracker may suddenly try to track part of the glasses frame. This typically occurs when there is a small reflection that gets mistaken for the Corneal Reflection. This can be prevented by enabling the Search Limits feature (make sure Use Search Limits is highlighted on the Camera Setup screen), then resizing the size of the limiting ellipse so that it fits entirely within the frame of the glasses and excludes the problematic reflection. The Search Limits can be resized by holding down the ALT key and pressing the arrow keys on the Host PC keyboard. Be sure not to make the Search Limits any smaller than the green box which bounds the eye.

In Remote mode, glasses are typically fine, but with the caveat that since the participant is free to move their head, they may move into a position where the glare off the lenses which can disrupt tracking.

If using the EyeLink II, glasses are typically fine but some frames can occasionally block the corneal reflection illuminators. If there is trouble tracking in Pupil - CR mode with glasses, try switching to Pupil Only mode.