They are so shy!
Introduction
When you look at a blue sky you may see shapes floating through your field of view. These things seem to drift to the side and then jump rapidly back. They are called floaters.
Material
All you need is a clear blue sky.
To Do and Notice
Look at the blue sky.
Notice small shapes that seem to drift across your field of view.
Try to look at them.
Notice that they move aside as you try to look at them and then jump back to their original position.
What do you see?
Some people see dots, others blobs and some see worm-like shapes.
What's Going On?
The blood supply to your retina leaks out into the vitreous humor. Red blood cells which make the dots, and white blood cells make the blobs. Chains of red blood cells stick together to make the worms. These are normal.
Do not worry unless you see a hundredfold increase in the number of floaters. Then, go to see an eye doctor.
Can you figure out why they move?
They are fixed in place in front of your retina. As you try to look at them your eye rotates, so they always move ahead of where you are looking. Thus they seem to drift across your field of view. When your eye gives up and returns to look ahead, the floaters jump back to their original position.
Slowly, over weeks, the floaters are cleaned out of your vitreous humor.
|
Scientific Explorations with Paul Doherty |
|
22 May 2000 |