Contrast sensitivity

The ability of our eyes to distinguish contrasts diminishes throughout our lives.
This is perfectly normal.
Contrasts in this context mean the difference between an object and its background.
If our contrast visibility is impaired, what we see becomes more and more blurred and colours become weaker.
Contrast visibility is measured on a contrast panel such as this one.
The further down you are able to read, the better your contrast visibility.
Incorrect prescription glasses or eye disorders such as cataracts, glaucoma and AMD may adversely affect contrast visibility.
On a standard eye chart, your visual acuity is tested using a white background with solid black lettters But the world is not entirely black and white.
If you compare the vision measured on the normal eye chart with the measurement of contrast visibility, you get a more exact picture of the functional vision, the real sight, the vision we see the world with.
If you have impaired contrast visibility, you will experience visual difficulties even if your visual strength is perfectly normal.
Do you feel unsafe when driving at night?
it may be because your contrast visibility is impaired.
During the day, you may not experience problems because there is enough light but when it's twilight or dark...
you might struggle to spot potholes in the road or changes to the terrain.
If your contrast sensitivity is heavily reduced, in daylight you may struggle to see changes in terrain because you can't see the shadows.
If you can't see the shadows, it's hard to tell the difference between a curb and a cobblestone.
A grey concrete staircase can almost look like a downward slope.
You may struggle to see the shadows of the crooked slabs on the pavement.
So impaired contrast visibility can often cause falls, especially in the elderly.
For some people, glasses with coloured filter lenses can enhance contrast thus making the differences in terrain clearer and reducing glare.
In bright sunlight, the shadows appear darker, so you can better see any potholes and differences in terrain.
That's because light is contrasting.
Good home lighting is important to all of us.
But it's even more important if you have reduced contrast visibility.
Lighting should be adapted to your activity, e.g. reading.
The right reading light can be contrasting and make the text of the newspaper appear blacker, and whiter.
If your contrast visibility is impaired, it's worth thinking about the contrasts in your daily life.
A good example is sitting at a a table with a white tablecloth with a white bowl of white yoghurt.
You may struggle to see where one starts, and the other ends.
But if you keep the white table cloth..
and instead use a dark bowl for your yogurt you've created clearer contrasts so you can see all three things better.
A dark placemat can make a white plate easier to see.
If you're going to pour coffee in a cup, pick a white cup.
If you're going to pour milk in a cup, pick a dark cup.
If you're going to chop white onions, do it on a dark chopping board.
If you're going to chop red onions, do it on a white chopping board.
These are all examples of how good contrasts can make daily life easier when you have reduced contrast visibility.
In general, if you have reduced contrast visibility make sure you have good lighting watch out for differences in terrain and think about contrasts in your daily life.