If you wear both contacts and glasses, you probably
already know that the prescriptions for each are a little different from
one another. Although they are similar, contact prescriptions vary due
to the nature of the contact lens itself. Of course, not many people
ever know this is the case, because they rarely look at their
Some also assume that when they have a standing glasses
prescription that they will be able to get contacts using it. While it
is possible, many doctors will not fill a prescription as such. If you
are curious however about the differences between the two and the
reasons for those differences, take a look at these explanations.
A) Why are they different?
The main difference between the
prescription for glasses and the prescription for contacts is due to the
nature of the contact lens. Contact lenses are made to fit right onto
the eye, which allows a great deal of astigmatism to be corrected.
Glasses lenses must be ground to specific sizes in order to correct
astigmatism. The fact that a contact lens sits right on the eye affects
the prescription, because your eyes are obviously seeing through
something much closer with a contact lens than they are when you wear
your glasses. Most doctors like to fit you for contacts however. During
the fitting they will also discuss any questions, concerns, handling
procedures, and any other pertinent contact topics. Going through this
type of contact fitting ensures that you are prepared to deal with
contacts in a responsible manner.
B) How are they different?
actual prescription for contacts differs a bit from a glasses
prescription in the way that it looks. A contact prescription will have
the type of contact lens being prescribed. It will have a notation if
any tint is being used. Some contacts are tinted slightly to allow
wearers ease when trying to find them in their case or if they are
accidentally dropped. Others are tinted to change the hue of your eye
when you wear them. A contact prescription will also include the base
curve, which determines the tightness of the lens, and diameter of the
contact lenses. To show the power of the lenses, there is a plus or
minus sphere power. This tells the maker how strong the lenses should
be. Sometimes there is also a cylinder power and an axis, especially in
C) Always see a professional
There is a wrong
notion among people that they can use their prescription of glasses for
contacts also. However, this is not the case. It is utmost important
that you visit a professional if you are considering contacts as option.
The professional apart from knowing what types of contacts you need,
will also tell you how to fit the contacts. Do not try to skip this step
as you can risk damaging your eyes forever.
As you can see,
glasses and contact prescriptions are indeed not created equal. The fact
is however that glasses and contacts are not equal in form and use so
the fact the prescriptions are not the same should come as no surprise.
When you have both glasses and contacts, you need to get two separate
prescriptions for each. Be sure to tell your doctor if you are
interested in contacts before the exam is finished so he or she can fit
you for them during the exam. You will most likely pay a higher fee
however when being fitted for contacts. Most of the time the higher fee
also includes one trial pair of contacts, solution, a case, and a follow
up visit as well. Your doctor will likely put you on a contact wearing
schedule in order to get your eyes used to your contacts.