If you have both contact lenses and glasses, you may have noticed that your prescriptions for each product differ slightly. Similarly, glasses-wearers may wonder if their regular prescription will work for contact lenses as well. Most people will have a different prescription for each product. As the conversion between a glasses prescription and a contact lens prescription is complicated and delicate, you should verify your prescription with a doctor before ordering your new contact lenses.
There are separate exams performed for contact lens and eyeglasses. Sometimes these prescriptions may be the same and sometimes they may not be. You should really leave up to your optometrist to perform a proper exam and determine which brand of contact lenses you should use. Also, optical stores are not allowed to sell you contacts without a valid contact lens rx, so you would have to get an eye exam done anyway if you want to buy contacts.