Can prescriptions for eyeglasses and contacts be identical?

[Hymas]

I went to the Walmart vision center and paid them $96 to update my prescription for glasses and contacts. However, the prescriptions are the same for both the glasses and contacts. As in, the power is -3.50 for both prescriptions. I was under the impression that because contacts are on the eye, but glasses are a few millimeters in front of the eye, the power would need to be different? I went in and asked to confirm the prescription and the clerk assured me that was what the optometrist had written in my file, but I'm worried I'll either end up with glasses that aren't strong enough, or contacts that are too strong. I already ordered some glasses, so it's too late for that, but I'm holding off on ordering contacts until I get a second opinion on this.

Additional Information: the contact prescription is for Biofinity brand. Not sure if that matters. Maybe they include a correction factor for their lenses in the power to bring them in line with glasses.

[John C Hagan III, MD, FACS, FAAO]

You went to Walmart's for eye care what did you expect? Mayo Clinic care.  You are right the prescription varies depending on how far it is away from the eye (vertex distance).  So as you surmise the either the glasses RX or the contact lens will be either too strong or too weak.  Many people cannot tell the difference though.

[Hymas]

Thank you for the reply! Unfortunately I'm a poor college student living off of loans, so I couldn't afford somewhere better. Hopefully I'll be one of the ones who can't tell a difference

[John C Hagan III, MD, FACS, FAAO]

I suspect you will not as the difference between the two would calculate out to only about 0.25 diopters