Contact Lens Prescription vs. Eyeglass Prescription

First of all, the fact that the correctable lens is sitting right on your eye with contact lenses can be a factor causing the prescription to be different. Typically, if the contact lens prescription differs from the spectacle prescription, it will be a little bit less. A contact lens prescription also contains information about the shape of your cornea (the clear part at the front of your eye onto which a contact lens sits). This is important information in determining the shape and size of the contact lenses you need. Since eyeglasses do not touch your eye, there is no need to provide this information on a spectacle prescription. Be sure when you are ordering contact lenses that you know the prescription number, including:

1. the prescription,
2. the base curve, and
3. the diameter of the lenses you need.