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Science: Health: Eye: Contact Lens
Contact lens orientation indicator   (+8)  [vote for, against]

Modern soft contact lenses are extremely flexible - mine are 55% water. As a result, it's possible, while cleaning them, to flip them completely inside out, and it can be difficult to determine whether they've been re-flipped. They have a different profile when inside out, but you need to view the lens edge-on against the light and it can be tricky to spot. After all, without my lenses in, I cannot see properly. When inside out, the lens still fits the eye and vision is still corrected, but neither function is as good as it should be.

I propose that the words "This side towards eye" be printed in large friendly letters on the inside surface of contact lenses.
-- angel, Nov 30 2005

Acuvue mark on side of lens. http://www.jnjvisio...cts/inside_out.html
[jutta, Nov 30 2005]

This is like my Fathers suggestion that contact lenses be made of fluorescent plastic to make them easier to find when you drop them.....
-- Minimal, Nov 30 2005

My lenses (and, I assume, most others) have a 5% blue tint, called a 'handling tint', to make them visible when immersed in water.
-- angel, Nov 30 2005

what a joker!
-- po, Nov 30 2005

You could use one-way signage (I'll see if I can find a link) to make the writing only visible from one side. I wouldn't want my eyeballs reading "eye sdrawot edis sihT" all day. [+]

[later] Can't find anything good on the internet. Basically it's a neutral colour grid of dots overprinted with an image so that from one side you see image and from the other just a grid of dots. Make the dots small enough and you don't notice them.
-- st3f, Nov 30 2005

like the adverts on the buses?
-- po, Nov 30 2005

You're lucky that flipped lenses still function for you. I also can see through my lenses when the wrong way out, but I get terrible dizzy-type nausea after about 2 hours. What is most annoying is that even when I flip the offending lens right way out, the nausea persists :-(

Some kind of marking that is obviously right-way-out/wrong-way-out would work. My lenses already have small markings on the lower edge to show which way up they go in my eyes.
-- Katisha, Nov 30 2005

i thought this was a contact lens compass
-- theircompetitor, Nov 30 2005

[Katisha]: I have the same dizzy-nausea problem, hence my requirement. My lenses have no "This side up" marking as my astigmatism is minimal, but my suggested text would serve this purpose also.
Actually, any symbol which is asymmetric (such as & or @) would suffice.
-- angel, Nov 30 2005

Acuvue has an "inside-out mark" that spells out "1-2-3" or "AV" when seen from the side in a correctly turned lens. (See link.)
-- jutta, Nov 30 2005

If there was a small dot cast inside the lens near the edge that appeared as a small white dot from the wrong side, and a small black dot from the right, then, once the lenses were in you could look in the mirror. If you could see the white dot, then you would know that you had the lenses on inside-out!
-- Minimal, Nov 30 2005

[jutta]: Damn! Obviously a good idea then (although intended to be tongue-in-cheek).
-- angel, Nov 30 2005

//although intended to be tongue-in-cheek//

Surely, eye-in-socket.
-- skinflaps, Nov 30 2005

Interestingly enough my contact lens do have letter markings on them already. I buy them from acuvue!
-- mikeyg, Nov 30 2005

someone wake mikey up.
-- po, Nov 30 2005

random, halfbakery