Schizophrenia diagnosed by simple eye test

SCIENTISTS have discovered an almost 100 per cent accurate method to detect whether a person has schizophrenia – a simple sight test.

Impaired eye movement has long been thought to be associated with schizophrenia.

Now a new Scottish study has reported a model of testing that demonstrates 98 per cent accuracy in distinguishing between those with and without 
schizophrenia.

Using “simple viewing tests”, researchers at Aberdeen University explored the ability of eye movement tests to sort schizophrenics from healthy people.

Those with schizophrenia showed well-documented deficits in ability to track slow-moving objects smoothly with their eyes. Schizophrenics also found it more difficult to maintain a steady gaze.

The study was led by Dr Philip Benson and Professor David St Clair, and involved a range of eye tests where volunteers were asked to track slow-moving objects slowly with their eyes (known as smooth pursuit); inspect a variety of everyday scenes (free viewing); and given instructions to keep a steady gaze on a single, unmoving target (fixation tasks).

Their findings could speed up detection of the condition and they are now examining whether the tests can be used for earlier intervention in major mental illness.

Dr Benson said: “It has been known for over a hundred years that individuals with psychotic illnesses have a variety of eye movement abnormalities but until our study, using a novel battery of tests, no one 
thought the abnormalities were sensitive enough to be used as potential clinical diagnostic 
biomarkers.

“In smooth pursuit, people with schizophrenia have well-documented deficits in the 
ability to track slow-moving objects smoothly with their eyes. Their eye movements tend to fall behind the moving object and then catch up with the moving object using rapid eye 
movements.

“In the free-viewing test, whereas most individuals follow a typical pattern with their gaze as they scan the picture, those with schizophrenia follow an abnormal pattern and, in 
the fixation task, individuals with schizophrenia found it more difficult to maintain a steady gaze.”

Several methods were then used to model the data, and the accuracy of each of the created algorithms was tested by using eye-test data from another group of cases and controls. Combining all the data, one of the models achieved 98 per cent accuracy.

Professor St Clair added: “Typical neuropsychological assessments are time-consuming, expensive and require highly trained individuals to administer. In comparison, these eye tests are simple, cheap and take only minutes to conduct.

“This means that a predictive model with such precision could potentially be incorporated in clinics and hospitals to aid physicians by augmenting traditional symptom-based diagnostic criteria.”

The Scottish research is published in the November issue of the academic journal Biological Psychiatry.