Eye Tracking Disorders in Schizophrenia
With so much focus on eye tracking studies for web design and usability, it’s nice to touch on some other subjects now and again. Eye tracking technology is often used in medical and diagnostic studies, and a recent report describes a test regarding eye movement abnormalities in schizophrenics.
Schizophrenia is a psychiatric disorder that affects nearly 1% of the general population. Yet as common as the condition is, it’s nature often manages to both elude and fascinate psychiatrists. Genetic studies on schizophrenia are frequently conducted, and one of the more objective tests is for the detection of eye tracking disturbances or smooth pursuit eye movements, with the presence of eye tracking disturbances reported often in the biological relatives and twins of schizophrenics.
Researchers at the Centre for Ophthalmic Sciences, All Institute of Medical Sciences in New Delhi, India, published a report some years ago which utilized eye tracking technology using electrodes placed on the patient’s face. The researchers performed four tests on each patient, observing the results to develop insight into the diagnosis of schizophrenia and eye tracking disorders. The different eye tracking disturbances studied included: gain of pursuit movements, frequency of catch-up and back-up saccades, anticipatory saccades and square wave jerks, and log stimulus-noise ratio and the time-off the target per cycle.
Twenty-two patients with schizophrenia ranging from 21 to 43 years of age took part in the test. All patients were on anti-psychotic drugs. An additional 15 patients without schizophrenia were matched as a control group. Patients were equipped with electrodes at the nasal and temporal canthi of each eye (the corner of the eye where the upper and lower eyelids meet), with another placed on the forehead, after which they were seated at a fixed distance from an oculomotor stimulator, which has an array of multiple light-emission diodes that generate smooth target movements without any moving parts.
The average pursuit gain test was found to be less in schizophrenics while frequency of saccades was higher. The frequency of catch-up and back-up saccades were only marginally more in schizophrenics and deviation during steady fixation was more frequent in the schizophrenic patients.
Eye tracking disturbances were generally found to be more unique to people with the condition, with bipolar and unipolar patients performing normally on a regular basis in past studies. Eye tracking disturbances have been suspected to be more frequent and consistent in schizophrenics, with past studies involving qualitative observations as well as global quantitative scores.
The article states that a simple assessment of the frequency of anticipatory saccades can be further studied as a possible biological diagnostic test for schizophrenia. The results of the study showed electro-oculographic recording of eye movements tracking a target to be helpful in the general diagnosis of schizophrenia.
Eye tracking disturbances in Schizophrenia
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