Wednesday, May 26, 2010

How do contact lenses work?

When I began wearing glasses when I was a kid, the world all of a sudden became much clearer. Without squinting, I could read the blackboard, see the television or read street signs with ease, which was great. However, even though you couldn't tell now, I was extremely athletic and involved with various sports all the way from my childhood through high school (and a little in college, until my laziness gene must have really kicked in).

Wearing glasses isn't really the most favorable option when you're upside down in gymnastics or in the air spiking a volleyball, so it was time to move on to the better solution: contact lenses.

But... they're just a thin, transparent, plastic disc that sits right on the cornea of your eye. So today I set out to answer my own question: How the heck do contact lenses work?

There is a whole lot of interesting information that I found online to answer my query and it all comes down to the way light enters into your eye. If you have normal vision (is there anyone left out there that doesn't need some sort of vision correction anymore?), light enters your cornea in the front of the eye and is directed right to the retina in the back of the eye. It then turns into images and heads to your brain so that you can understand them, simple as that.

But, if your eyeball is a slightly different shape, it causes the light to not be directed on the retina and then the resulting images are blurry. If you are nearsighted, like me, your eyeball is a little too long and the light is focused in front of the retina. I can see things clearly up close, but not far away. Therefore, contact lenses work by being thin in the center and spreading the light rays away, moving the focal point up to the retina.

If you are farsighted, then it is the opposite and your eyeball is too short. On its own, light is focused behind the retina and close-up vision is blurry. To help, these contact lenses are thinner at the edges so that the light will be moved toward the center and redirect the focal point backwards onto the retina.

Got all that? The other factor that I found I had to deal with was astigmatism (an irregularly-shaped cornea that causes light to focus at several points, distorting it) and it wasn't until a few years after I began wearing contact lenses that I discovered there were options out there to correct this.

Instead of wearing contacts that have their power correction the same all throughout, lenses for astigmatism (called toric lenses) have various different angles and thicknesses in them that work for each individual and the level of correction that they need. There are various brands available (I'm sure you've seen the commercials for Acuvue Oasys for Astigmatism contacts with the cute, peppy teenagers) and if you have never tried contact lenses due to your astigmatism, I highly recommend it. The world can be a beautiful place when it is in focus!

What do you think about contact lenses? Do you wear them? Are you still baffled (like me) that a tiny piece of plastic can make such a difference in your vision?

(I was compensated for writing this post by but the rambling about how contact lenses work was my idea - aren't you lucky?)


jacque4u2c said...

I love my contact lenses - I have worn them for years. I can;t stand my glasses - especially this time of year when you are out doors and sweating - glasses are such a pain!

LeeAnn said...

I loved contact lenses for the short time I could wear them. I became allergic to them after only a few months. I have tried many different kinds and they all make me feel like I have bugs crawling around in my eyes. Boo!

Susan Fobes said...

I'm a contact lens wearer and it's only because I hate glasses so much. Unfortunately, the computer has done wonders for my eyesight (not) and a slight astigmatismin my left eye is much worse. I am not wearing lenses to correct the astigmatism and my doctor warned me that I might not like them because my close vision would be affected. Well I things far away have never been clearer, but now I've had to buy those ugly half glasses for reading small print. Ugh!

Becca said...

I have been wearing contact lenses on and off for the last 14 years and I love them. They make my vision so crisp and clear! I recently hurt my eye somehow and had to wear glasses for 2 weeks and did not enjoy it. I do marvel at how contacts for astigmatism stay in place tho!