The study, conducted by Ludger Tebartz van Elst and colleagues measured electrical responses to gauge the activity of the retina in groups of depressed and non-depressed individuals. At the back of eye is the retina, home to a number of sensitive cells which turn light signals into nerve impulses which, when interpreted by the brain allow us to see.
Those who were depressed were found to have a reduced retinal contrast than the participants who were not suffering with depression and though there did not appear to be a difference between those taking antidepressant medication and those taking nothing, there was a difference between contrast levels and the severity of their depression, with the most severely depressed having the lowest response.
The findings were published in the journal Biological Psychiatry, the editor of which said: “These data highlight the ways that depression alters one’s experience of the world. The poet William Cowper said that ‘Variety’s the very spice of life’, yet when people are depressed, they are less able to perceive contrasts in the visual world. This loss would seem to make the world a less pleasurable place.”
These findings could eventually help to determine depression’s severity and are an accurate way to assess mood.
Dr van Elst said: “This method could turn out to be a valuable tool to objectively measure the subjective state of depression, having far-reaching implications for research as well as clinical diagnosis of and therapy for depression.”