Contact lenses --- degrees help please?!


Question: Contact lenses --- degrees help please.?
hi
i know how much degrees i am for my glasses, but i want to get contact lenses and i am confused~
they ask me "power" and theres like a list of degrees
-3.00
-2.00
-1.00
0.00
+1.00
+2.00
+3.00

it ranges from -9.00 to +9.00
i was wondering how do i know if im a positive or negative.?
i wear regular glasses becuase i cant see things far away. thanks!Health Question & Answer


Answers:
positive is for nearsighted people (meaning you cant see far away)
negative is for far sighted people (meaning you cant see close)

im sure your know how much degrees you are so approximate. if youre 3.25 degrees (normal glasses) you should be +3.25. if youre 3.25 degrees (reading glasses) you should be -3.25.

hope this helped!
*always ask your doctor before buying contact lenses!Health Question & Answer

I know that the minus is nearsightedness. I used to be -450, and could barely make out the Big E. (Before Lasik)
You know, there's an "optical" category, also under "Health." I just don't know that much. Anyway, your eye doctor will be happy to explain all of that to you. :)Health Question & Answer

I think your best bet would be to get an eye exam before you get contacts. Most places require an up-to-date exam anyways, just to make sure you get the right prescription.

That way you know for sure =]Health Question & Answer

I WEAR CONTACTS MYSELF, FOR 14 YRS. TO BE EXACT. YOU SHOULD GO TO YOUR EYE DOCTOR, YOU LL NEED A "CONTACT FITTING".Health Question & Answer

The strength of a lens is measured in diopters, abbreviated D.

The higher the number of diopters, the stronger the lens.

A +10 diopter lens would make a good magnifying glass.

Eyeglass lenses are usually much weaker, because eyeglasses do not work by magnifying; they work by correcting focus.

Stacking lenses combines their strength.

A +1 diopter lens combined with a +2 diopter lens forms a +3 diopter system.


Lenses come in positive (plus) and negative (minus) strengths. You can usually tell whether a lens is positive or negative by LOOKING through it. Positive lenses tend to enlarge things when you look through them; negative lenses tend to diminish the size of things when you look through them. Because eyeglass lenses are usually weak, they don't enlarge or diminish very much.

Positive eyeglass lenses can concentrate sunlight, like a burning glass. However, they are usually much too weak to set fire to anything. As the distance from the wall increases, the shadow of the frame seems to thicken and the bright area in the center gets smaller and brighter. It slowly changes from being "eyeglass-shaped" to circular.


Negative lenses spread sunlight instead of concentrating it.

A negative lens combined with a positive lens removes some of its strength. A -2 lens combined with a +5 lens forms a +3 diopter system

A -3 lens stacked on top of a +3 lens looks almost like clear glass, because the combined strength is 0.


So your reading of -9.00 to +9.00 falls within this range. for your farsightedness or hyperopia. Farsightedness or hyperopia means that the eye focuses better on distant objects than on those that are close


Another way of description:

In science textbooks, positive lenses are usually diagrammed as convex on both sides; negative lenses are usually diagrammed as concave on both sizes. In a real optical system, you usually get the best optical quality when most rays of light are roughly normal to the lens surface. In the case of an eyeglass lens, this means that the lens should be roughly shaped like a cup with the hollow side toward the eye. So most eyeglass lenses are meniscus in shape.

For an accurate fitting of contact lenses, it's imperative, that you bring your eye prescription from the optician or opthalmologist. Nowadays, mandated by law, you can obtain your prescription and have it filled by any office /hospital of your choice.Health Question & Answer



The consumer health information on youqa.cn is for informational purposes only and is not a substitute for medical advice or treatment for any medical conditions.
The answer content post by the user, if contains the copyright content please contact us, we will immediately remove it.
Copyright © 2007-2012 YouQA.cn -   Terms of Use -   Contact us

Health Q&A Resources