In most cases, you cannot use an eyeglasses prescription to buy contact lenses. This is because eyeglasses and contact lenses require different prescriptions, as the lenses are worn in different ways and sit at different distances from the eye.
A prescription for eyeglasses provides information about the corrective lens power needed to compensate for a person's refractive error, such as nearsightedness, farsightedness, or astigmatism. It may also include information about the distance between the eyes (pupillary distance) and other measurements specific to eyeglasses.
A contact lens prescription, on the other hand, provides additional information such as the base curve of the lens, the diameter of the lens, and the brand and type of lens that is appropriate for the individual. This information is needed to ensure that the contact lenses fit properly on the eye and provide the necessary vision correction.
In some cases, an eye doctor may provide a prescription for both eyeglasses and contact lenses during the same eye exam. However, if you only have an eyeglasses prescription and want to buy contact lenses, you will need to schedule a separate contact lens fitting with an eye doctor who can provide a prescription specifically for contact lenses.