The Federal Trade Commission (FTC) has sent 28 warning letters to eyeglass prescribers warning them of potential violations of the FTC’s Ophthalmic Practice Rules, known as the Eyeglass Rule, which enables consumers to comparison shop for prescription eyeglasses.

The Eyeglass Rule requires prescribers to provide patients with a copy of their eyeglass prescription immediately after an eye exam that includes a refraction (the test a prescriber uses to get a patient’s eyeglass prescription), even if the patient does not request it.

Under the Rule, prescribers cannot require that patients buy eyeglasses as a condition of providing them with a copy of their prescription, place a liability waiver on the prescription, require patients to sign a waiver, or require patients to pay an additional fee in exchange for a copy of their prescription. In addition, prescribers cannot refuse to perform an eye exam unless the patient buys eyeglasses, contact lenses or other ophthalmic goods from them.

Consumers can use their prescriptions to buy eyeglasses wherever they are sold—from another prescriber, a store or online.

The FTC stated that it had recently received reports that some eye care professional offices had failed to provide consumers with their eyeglass prescription at the end of an eye exam. The FTC staff sent those offices the letters reminding them of their obligations under the Eyeglass Rule.

Some prescribers who provide contact lens fittings in addition to eye exams were also warned of potential violations of the agency’s Contact Lens Rule, which requires prescribers to provide a copy of the contact lens prescription to the patient at the end of the contact lens fitting, even if the patient does not request it. The Contact Lens Rule also prohibits prescribers from requiring that patients buy contact lenses, pay additional fees, or sign a waiver or release as a condition of releasing or verifying the prescription.

The letters warn the prescribers that violations of the Eyeglass Rule or the Contact Lens Rule may result in legal action, including civil penalties of up to $42,530 per violation.