What colours we see depends not just on how things are in the world around us, but also on what happens in our eyes and our brains.
Screen time wasn't a issue in the 19th century but that didn't stop concerns over how new developments might damage eyesight
For roboticists looking to nature for inspiration on how animals see the world, there's a tension between mimicking biology and capitalising on the advances in camera technology.
Many people have an appearance of dark circles on the lower eyelids, and they have many different causes.
In an ant's world, the smaller you get the less you can see. So how does that affect an ant's ability to avoid hitting any obstacle as it walks about?
Many people, from children to the elderly, wear glasses. Andy, age 5, wants to know how they work.
Whether we're happy or sad, it doesn't take much to turn on the waterworks. But how and why do humans cry?
They're more than windows into the soul – they're a portal into our possible future.
We're used to thinking of our eyes detecting light as the foundation of our visual system. But what's going on in other cells throughout the body that can detect light, too?