Eye monitors
Infra-Red Oculography
IR lights illuminate the lower portion of the pupil. Sensors measure the reflected light. Eye movements cause a different amount of light to be reflected on the sensors. These systems are low cost, portable, and are great for measuring horizontal saccade latency. Inexpensive, portable and offer good temporal resolution. However, these designs have a poor vertical signal and requires chin rest.
Remote video imaging
The eye is illuminated with infrared lights. An IR-filtered video camera records the positions of the pupil and the corneal reflection (glint from IR lights). These landmarks to compute the point of gaze. A good, general purpose technique.Does not require chin rest, good vertical and horizontal signals and completely non-invasive (no head gear). However, remote video systems are disrupted by sunlight (high IR) and have poor temporal resolution (50-240 Hz).
ASL 210/310

The Applied Science Laboratories 210 system is a head mounted infrared reflection eye tracker. Typically, horizontal position is sampled from one eye, and vertical position is sampled from the other eye. We have mounted the 210 to a pair of optician's fitting frames (see photo, left), allowing us to record eye position from individuals who require perscription lenses.
ASL 504

The 504 is a remote video eye movement monitor, which samples the eye position at 60 Hz. This is the only remote eye monitor available which is portable (I often bring it to patients homes, the system requires the camera and controll unit [pictured] as well as a laptop computer and TV monitor). The entire system will fit into a large duffel bag.
Homemade Eyemonitors

Infrared eye monitors are fairly easy to build. I designed the system on the left with my dad (who designs medical lasers).This system only measures horizontal eye position, and uses an international 5.25 inch hard disk drive enclosure for power (shown with Skalar 6500 mount).
Data recording and analysis

I have written Windows and DOS software to record eye movements in real time, using high performance timers. I generally record data in a compressed binary format. In addition, my freeware Windows EMview software allows offline data analysis. The current version of the software allows efficient analysis of:

  • Peak velocity, time to peak, peak to rest.
  • Saccade identification (velocity criterion).
  • Fixation identification.
  • Data filtering/averaging.

For more information

Visit the Eye Movement Equipment Database, which covers virtually all the eye monitors on the market.