# Vision q's - Floaties, -10/-10 and legally blind **URL:** \ **Category:** Factual Questions\ **Created:** [November 13, 2003, 5:22pm UTC](https://boards.straightdope.com/t/vision-qs-floaties-10-10-and-legally-blind/213053 "2003-11-13T17:22:19Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![audreyayn](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@audreyayn](https://boards.straightdope.com/u/audreyayn)\ **Post date:** [November 13, 2003, 5:22pm UTC](https://boards.straightdope.com/t/vision-qs-floaties-10-10-and-legally-blind/213053/1 "2003-11-13T17:22:19Z")
1. What are the floaty things in my vision? A friend of mine has them too, and described them better than I can: "Like seeing single-celled organisms and bacteria floating in your vision, if you focus in the proper lighting for a time. Falling with gravity… always falling with gravity. But it looks odd, and I see it no matter where I look, or what I look at. " What’s more, I’ve always had the same floaties–I can tell because one of them’s shaped like a kangaroo. 2. I was recently told I have -10/-10 vision, and I’m wondering what that means. I’m guessing that possibly 0/0 is that point I hit in high school when I stopped being able to see anything clearly without glasses on. 10/10 is being able to see something at 10 yards that someone with perfect vision could see at 20 yards, isn’t it? 3. How blind is legally blind? Because even with -10/-10 vision I’m able to navigate just find, so long as I’m not required to read or go up and down badly lit steps. ---
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [November 13, 2003, 5:32pm UTC](https://boards.straightdope.com/t/vision-qs-floaties-10-10-and-legally-blind/213053/2 "2003-11-13T17:32:28Z")
[Floaters](http://www.allaboutvision.com/conditions/spotsfloats.htm) And welcome to the board! ---
**Author:** ![Jake4](https://avatars.discourse-cdn.com/v4/letter/j/bc8723/32.png) [@Jake4](https://boards.straightdope.com/u/Jake4)\ **Post date:** [November 13, 2003, 5:34pm UTC](https://boards.straightdope.com/t/vision-qs-floaties-10-10-and-legally-blind/213053/3 "2003-11-13T17:34:58Z")
-10/-10 sounds like the prescription for your glasses, not to be confused with the ‘20/20’ method of determining vision. I can’t see anything 10 ft. behind me… ---
**Author:** ![Phoebestar](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Phoebestar](https://boards.straightdope.com/u/Phoebestar)\ **Post date:** [November 13, 2003, 7:40pm UTC](https://boards.straightdope.com/t/vision-qs-floaties-10-10-and-legally-blind/213053/4 "2003-11-13T19:40:38Z")
Just as a reference: Last year, the (uncorrected) vision in my right eye became too bad to measure with numbers, so instead of 20/200, etc., the doctor called it “CF”, for “Counts Fingers” from so many feet away (2, maybe?) Basically, I couldn’t see the biggest letter on the vision chart. My left eye is about 20/700. I think the -10 stuff is your glasses precription. Here is an example of a prescription and what the numbers mean: [http://www.eyeglassdirect.com/about-rx.htm](http://www.eyeglassdirect.com/about-rx.htm) ---
**Author:** ![rowrrbazzle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rowrrbazzle/32/414_2.png) [@rowrrbazzle](https://boards.straightdope.com/u/rowrrbazzle)\ **Post date:** [November 13, 2003, 10:26pm UTC](https://boards.straightdope.com/t/vision-qs-floaties-10-10-and-legally-blind/213053/5 "2003-11-13T22:26:42Z")
Cecil on floaters: [http://www.straightdope.com/classics/a2\_311.html](http://www.straightdope.com/classics/a2_311.html) One interesting part: > [@](#): > > The little threads are believed to be the sad remnants of the hyaloid artery, which nourishes the lens and other parts of the eye during fetal development and then withers away. ---
**Author:** ![audreyayn](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@audreyayn](https://boards.straightdope.com/u/audreyayn)\ **Post date:** [November 13, 2003, 11:29pm UTC](https://boards.straightdope.com/t/vision-qs-floaties-10-10-and-legally-blind/213053/6 "2003-11-13T23:29:50Z")
Thanks for the floaters info. Maybe I should ask what I’m doing wrong in searching the archives, since I know I searched for vision, blind and legally blind. My eye doctor also uses the fingers method, which is sort of embarrassing since I know the top letter is always E, I just can’t see it. The -10/-10 thing is my prescription, sorry. I’m afraid I still don’t understand how that corolates to the 20/20 thing, or where these numbers come from. ---
**Author:** ![c\_carol](https://avatars.discourse-cdn.com/v4/letter/c/e79b87/32.png) [@c\_carol](https://boards.straightdope.com/u/c_carol)\ **Post date:** [November 14, 2003, 12:01am UTC](https://boards.straightdope.com/t/vision-qs-floaties-10-10-and-legally-blind/213053/7 "2003-11-14T00:01:55Z")
Legally blind means that your _corrected_ vision is 20/200 or worse. Since you can apparently see OK with your glasses on, you’re probably not. ---
**Author:** ![Phoebestar](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Phoebestar](https://boards.straightdope.com/u/Phoebestar)\ **Post date:** [November 14, 2003, 4:16am UTC](https://boards.straightdope.com/t/vision-qs-floaties-10-10-and-legally-blind/213053/8 "2003-11-14T04:16:23Z")
> [@](#): > > \*Originally posted by audreyayn \* > \*\*My eye doctor also uses the fingers method, which is sort of embarrassing since I know the top letter is always E, I just can’t see it. > > The -10/-10 thing is my prescription, sorry. I’m afraid I still don’t understand how that corolates to the 20/20 thing, or where these numbers come from. \*\* Last time my eye doctor asked me what the top letter was, I didn’t even know there was a letter there. I bet I woulda known it was E if I’d thought about it. 🙂 Unfortunately, I don’t think it’s possible to directly get a vision reading (the 20/20 stuff) from a prescription. From what I can gather, they 1. Test your eyes to determine the 20/20, etc. 2. Adjust the lenses you’re looking through to look at the chart until you see 20/20 (or as close as possible). They then take the readings for those particular lenses. I could be completely crazy on this. Any optometrists/opthamologists/etc. care to chime in? ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [November 14, 2003, 4:25am UTC](https://boards.straightdope.com/t/vision-qs-floaties-10-10-and-legally-blind/213053/9 "2003-11-14T04:25:30Z")
-10/-10 means that both eyes are very nearsighted and require a negative, or diverging, lens of -10 diopters. A diopter is is a unit of focal length used in optometry. -10 means a negative lens with a focal length of 1/10 meter, which is very strong. Mine are on the order of -2.