Look up at a bright, blue sky and you may notice tiny dots of moving light. You aren’t imagining these spots. This is a very normal occurrence called the blue field entoptic phenomenon.
What Is The Blue Field Entoptic Phenomenon?
The moving dots you see when staring at the sky are created by your own white blood cells flowing through your eyes.
Blood flows to your eyes through blood vessels that pass over the retina — the part of your eye that acts as a receptor for all light. Red blood cells, which make up more than 90 percent of your blood, absorb blue light. White blood cells let blue light through to your retina, which then sends a signal of increased brightness to the brain.
When white blood cells stretch to pass through the blood vessels in your eyes, you may see dots that look like little worms moving around in your vision. This is most noticeable when staring at a wide, clear area—like a blue sky.
Speed of the moving dots vary in time with your pulse, accelerating with your heartbeat. You may also see a dark tail with the dot of light, which is a bunch-up of red blood cells behind the slower-moving white blood cell.
Is Seeing Moving Dots Normal?
Seeing moving dots when staring at a clear sky is normal. The white blood cell movement is a normal function of the eye, though not everyone notices the moving dots in their vision. These “blue-sky sprites” normally disappear after a second or less.
Are These The Same As Floaters Or Flashes?
Don’t confuse the normal blue field entoptic phenomenon with floaters or flashes—which can interfere with your vision and signal a serious eye problem. Moving dots caused by the blue field entoptic phenomenon are all the same size and shape. If the eye stops moving, the spots keep whizzing around.
In contrast, floaters, which are clumps in your vitreous, the gel-like fluid in your eye, differ in size and brightness. If the eye stops moving, the floaters settle down. If the eye moves, the floaters follow more slowly.
Flashes look like lightning streaks or stars, can last for 10 to 20 minutes and may come and go for several weeks or months.
When Should You See A Doctor?
Seeing moving dots when looking at a large, clear space—like the sky—is not a cause for concern. But if you notice a change in your vision or have a sudden onset of flashes or floaters, call an ophthalmologist right away. New or increased flashes or floaters can be a sign of a retinal detachment.