Monday, February 13, 2012

Floaters

Floaters are ghostly specks, dots, or lines that drift across your visual field. They’re most often visible in front of a smooth blue sky or a blank computer screen.

At left is a simulation from Wikipedia. You can’t look directly at floaters, because they exist at a fixed relationship to your direction of vision. As your eye moves to look at them, they dart away at the same speed.

Floaters are a normal experience for people with healthy eyes, but a lot of them can also be a sign of a retinal detachment or other medical problem. Normal floaters are caused by cell debris from the natural degeneration of the inside of the eye. Bits of protein material are suspended in the gel-like vitreous humour inside your eyeball and drift down like flakes in a snow globe.


10 fun facts about floaters:
  1. There’s a different set of floaters for each eye, and you can see each separate set of floaters by covering one eye and then the other.
  2. You get more floaters as you get older, but young people get them, too.
  3. Young peoples’ floaters tend to look more like transparent worms, older folks' floaters tend to be more like dark specks.
  4. Floaters eventually settle down to the bottom of the eyeball. During the day when you’re vertical, they settle at the bottom of the eyeball. During the night when you’re sleeping, they settle at the back. 
  5. If you tilt your head just right, you can sometimes get them to drift to the center of vision. 
  6. You don’t see the floaters, but rather the shadow they cast on your retina.
  7. Floaters are not optical illusions, but are called entopic phenomena
  8. In bright light, when the pupil is contracted, the shadows cast by floaters are sharper, so they’re easier to see.
  9. The gel-like vitreous humor gets more watery as you age.
  10. In French they’re called “mouches volantes,” which means “flying flies."
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Sources: Wikipedia

17 comments:

Michael Chesley Johnson said...
This comment has been removed by the author.
Michael Chesley Johnson said...

They also appear during a vitreous detachment. It's something I've experienced, and the event itself is quite remarkable - colorful lights at the edge of vision. (Not to be confused with a painless optical migraine, which can offer a stunning lightshow not unlike the aurora borealis.)

Michael Chesley Johnson said...

Er, not "optical" migraine but "ocular" migraine.

David Yanchick said...

In 3rd grade I pointed this phenomenon out to a fellow 3rd grader. We were sent inside from recess because we were standing in the outfield staring at these "worms" instead of playing kickball. :)

Jason de Graaf said...

The worst is on sunny days when there's lots of snow on the ground.

Love this... http://www.youtube.com/watch?v=3I7_al4mrfg

Greg Newbold said...

I have a few too many floaters which can be very annoying. I find myself going all shifty eyed sometimes when trying to get them to drift out of my field of vision. The worst is when I am reading. Feel luck if you just have a few.

James Gurney said...

Michael, I love ocular migraines. I call them "mystic floating donuts."

David, my son had your style for playing soccer. He kicked at the dirt to watch the cool dust effects, as the ball rolled by.

Jason, loved that Family Guy clip.

Greg, I know the feeling.

ChrisG said...

Don't underestimate how bad floaters can be. After my vitreous detachment ( and retinal tear) I had such nasty big black floaters that I could see them with my eyes shut. They can block your vision. Fortunately they improved with time...

Rachele said...

OMG! Thank you so much James! Since I was a child I always got mad seeing them, as I wasn't sure about what I was looking at, plus no one else seemed to see them...
But now I know.

Great blog. Great books. Great artworks.

Thanks.

Steven said...

Near-sighted folks will find them to be more pronounced... according to my opthomolgists.

Alex_Munguia said...

I brought this up once when talking to a friend of mine a while back. I wondered if others had noticed what I did...He said "Yeah, but I guess it's just something people don't talk about."

No one ever did so it's amusing that you are actually bloggin about this haha.

Good stuff.

David J Teter said...

YES!
I agree with Rachele and Alex.
I saw/see them and have tried describing it to others a couple times over the years.

People don't talk about it.
I was always afraid people would think I'm crazy or had abnormal vision so I kept my mouth shut.
THANK YOU!

Christel said...

While you might not like to see these floaters, there is something you can choose to look at within your eyes and which is quite fascinating!

We are actually able to see the network of little veins we have in front of our retina.

To do so, look at a light colored wall through a little hole formed by your index finger you have bent. If you keep making little circular movements with your hand, you should see luminous dots appearing, gradually forming a network of tiny wires. These are your veins! An empty circle should remain in the middle, which if I remember well corresponds to your blind spot.

I keep telling people to try it and how amazing it is but for some reason they often want to try that in private...

Cath Li said...

I used to think I was seeing bacteria or something.

Nice to know our eyes are like little snow globes.

Michael said...

I've had several eye surgeries, so I have a few more than most. They're great to watch, though. :D

Trish King Slaven said...

Something that has happened to me a couple of times is what looks like a small lightning strike that gets bigger and peripheral vision is gone. I see the floaters every so often, too.

Noomie Doodles said...

I've always observed these eversince I was small and when I daydream! Thanks for bringing this up, I finally know what it means.