Eye tracking for vision research

Cardiff University's School of Optometry and Vision Sciences used eye tracking from Tobii Pro to explore eye movement in people with sight issues. The researchers looked at how environmental factors affected vision deficits.

Diagnosing vision problems

Maggie Woodhouse and Jon Erichsen from the School of Optometry and Vision Sciences at Cardiff University in the United Kingdom use eye tracking from Tobii Pro in their research in order to better understand eye movements and eye movement problems, and as a way to develop a means of diagnosing problems in clinical situations. The research involves studying eye movement deficits such as nystagmus and strabismus (squint), clinical evaluation of eye movement control, and validation of tests supposedly detecting tracking difficulties.

People make continuous eye movements throughout the day while accomplishing a variety of important visual tasks like reading, tracking moving objects, compensating for head and body movements, or simply looking around to observe what is happening in their vicinity. With the right equipment, these eye movements can be quantified and analyzed, telling us a great deal about how people use their eyes, what they look at, and what they actually can see.

We are finding the systems from Tobii Pro very easy to use and very patient-friendly. The Pro T60 XL is going to allow us to extend our research into hard-to-test groups, such as children

Maggie Woodhouse, Senior Lecturer at the School of Optometry and Vision Sciences at Cardiff University

Eye tracking visual performance in people with nystagmus

For many years, the Cardiff Research Unit for Nystagmus has been studying eye movements of people with an early onset, continuous horizontal oscillation of their eyes that impairs their vision. Eye tracking has allowed researchers to quantify the dynamics of these eye movements and how they are affected by such environmental influences as stressful situations.

Until acquiring the Tobii Pro T60 XL eye tracker, these measurements could only be achieved by the use of equipment that had to be placed on the head, which limited the range of eye movements that could be tested.

The wider screen of the Pro T60 XL makes it much easier to present eccentric stimuli to investigate size and frequency of eye movements (in people with nystagmus affected by the orientation of the eyes in the head).

Experiments on how people do everyday tasks like reading or looking at complex images can be carried out much more straightforwardly with the Pro T60 XL because the system is completely noninvasive and measures vertical as well as horizontal eye movements. A particular strength of the widescreen eye tracker is the ease with which it can determine gaze direction (i.e. where a subject is looking) in real time.

Gaze plots from a person with nystagmus (on the left) and without  nystagmus (on the right).

The figures illustrate how differently a person with nystagmus reads as compared to a subject with normal vision.

Clinical evaluation of eye movement control in children

Other research at Cardiff aims to improve the clinical evaluation of eye movement properties, such as eye following (smooth pursuit) movements. In a recently initiated study focusing specifically on children, eye tracking will be used to answer the following questions:

  • How reliable are current clinical tests for evaluating eye movement control in children?
  • What impact do the surroundings and the instructions have on a child's ability to track a moving object in a clinical setting?
A young participant going through the calibration process on the T60XL eye tracker.

The hypothesis is that, when distracters are present and/or instructions are given at the outset and not reinforced during tracking, eye movement will be haphazard and tracking ability will appear poor. When distracters are removed and instructions reinforced in a child-friendly way, tracking will improve.

Studies of children with suspected tracking difficulties will be carried out to answer the questions. A Tobii Pro T60 XL Eye Tracker will be used for stimuli presentation and recording eye movement data, which will then be analyzed for the degree of tracking precision and consistency.

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