Contact Lens Comparison

Contact And Glasses Prescriptions Are Not Created Equal!

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 prescriptions.


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?
The 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 toric lenses.

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.