Whether or not your vision is impaired, eye exams are an important part of maintaining your health. Of course, those who do wear glasses and contacts need to get an exam regularly. The usual recommendation is at least once per year. Not only does this ensure prescriptions are up to date, but it also prevents damage to the eye from going unnoticed.

Because contacts and glasses are such different tools, they each have a separate eye exam to obtain a prescription. If you’re not sure what to expect when visiting your eye doctor, read on to learn the differences between each vision test.

What’s the Difference Between an Eyeglass and Contact Lens Exam?

Both glasses and contact lenses require you to get an exam prior to purchasing them, but there are significant differences in what doctors look at during each exam. That’s because eyeglass exams calculate a prescription for lenses that are further from one’s face, while contact exams must take other factors into consideration given how close they are to the eye. Additionally, contacts are considered medical devices, which come with their own requirements to obtain.

If you only wear eyeglasses, all you’ll need is a comprehensive eye test to get an updated prescription. This test looks at your visual acuity and overall eye health. It also measures depth perception, eye movements, color vision, peripheral vision, and how your eyes react to light.

For contacts, a contact lens exam is required in addition to a comprehensive eye test. The exam for contacts is slightly more extensive because doctors must determine the size and shape of a person’s eye before prescribing contact lenses that will be a good fit. They also need to confirm that you produce enough tears to comfortably wear contacts in the first place.

On occasion, eye doctors will also have those new to contact lenses try putting them in and taking them out as part of the test.

What Are Your Rights to Obtain Your Prescription?

Whether you wear glasses, contacts, or both, U.S. law requires your doctor to provide you with a copy of your prescription. In fact, once your exam is complete, your doctor should give you your prescription information without prompting. If they refuse to do so, or if they demand you purchase lenses through them, that’s against the law.

These laws are enforced by the Federal Trade Commission and apply to both ophthalmologists and optometrists. The Eyeglass Rule states the given prescription must include a patient’s name, the exam date, and when the prescription expires.

The Contact Lens Rule requires prescribers to supply similar information, as well as details relevant only to contact lenses, such as lens power, manufacturer, base, and diameter when applicable.

Prescribers aren’t allowed to charge patients for their prescriptions or require any additional action from them. When you get an exam, the test itself is the only thing you should be paying for. It’s your right to purchase from other providers if you choose to.