It’s Not All Black And White – Life Really Does Look Grey When You Feel Blue
The world really is a darker place for people with depression.
Research carried out in Germany has shown that when people feel down they really do see a greyer world.
The eyesight issues are linked to how the retina responds to contrast sensitivity which affects the quality of vision. Researchers investigated retinal contrast sensitivity in 40 patients with and 40 without depression.
When the groups looked at a checkerboard – a square of alternate small black and white squares -measurements were taken which showed that the depressed people had a dramatic reduction in their response to contrast changes – the black squares became lighter and the white squares appeared darker so the images they saw appeared overall more grey.
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London Vision Clinic surgeon, Glenn Carp, explains that you can have 20/20 vision but still not have the ability to see contrasts clearly.
The usual eye chart used in eye tests shows crisp black letters of varying sizes against a white background in well lit conditions; but the world is full of shades of grey (especially during winter in Northern Europe), and it is important to also measure contrast sensitivity. People hampered by low contrast sensitivity will have problems seeing distinct images in certain conditions.
“It’s the difference between seeing a zebra in the field or a grey horse”, Glenn told me using an African bush analogy. “You can tell which animal you are looking at by seeing the stripes of different colours.”
Meanwhile in dim city streets low contrast sensitivity can cause a person, for instance, to trip on a curb when they are unable to differentiate between the edge of the pavement and the road. It can also cause problems with night driving with the possibility of not seeing pedestrians wearing dark colours.
“In laser terms, if you have x amount of contrast before surgery, it should measure exactly the same after the operation – usually no better and certainly not any worse”, explained Glenn. “It is a matter of improving the quantity of vision while maintaining its quality.
“If it is lower for any reason after surgery – although this is rare with modern lasers – we would treat those components and then it would revert to how it was before.
“That is why we measure contrast sensitivity at the three month check up – not after one month – because it needs time for any residual swelling or dry eye to settle down. This is why, sometimes, in the early days after Laser Eye Surgery, night vision might appear a bit fuzzy.”