For the latest details on the Prescription Check service, click here.

NEW YORK—Warby Parker is stepping into the controversial field of online vision testing with the launch of a mobile refraction service that lets current customers measure their visual acuity using an app. Called the Warby Parker Prescription Check the test “helps eligible folks with expired eyeglasses prescriptions get a new one—without setting foot in a doctor’s office,” according to the company’s promotional literature.

The app, which can be downloaded from the App Store, enables consumers to take a 20-minute test on an iPhone or computer that determines the sharpness of their eyesight. Consumers then send their test results and their current prescription to a Warby Parker-affiliated eye doctor, who determines if their vision has changed since their last eye exam.

If the patient’s vision has not changed since their last prescription, the doctor will write them an updated prescription within 24 hours that can be used anywhere. If the patient’s vision has changed, the doctor may recommend that they get a comprehensive eye exam. Warby Parker did not specify whether an optometrist or ophthalmologist would review the results of the vision test.

Initially, Warby Parker is limiting the availability of the service to customers who live in New York, Florida, California or Virginia, although the company said it plans to roll out the tool to new states rapidly. Patients must be between 18 and 40 years old to use the service and must have had a comprehensive eye exam within the last five years.

Customers with a history of eye disease or risk factors are not eligible to participate. The service is currently limited to eyeglass wearers who have a single-vision distance prescription with a sphere between 0 and -6.0 diopters and a cylinder between 0 and -2.0 diopters.

Although advocates of online refraction maintain that it is expanding the availability of vision care to a larger population, the technology has met with resistance from some optometrists. A leading provider of online vision tests, Opternative, has come under fire from the American Optometric Association as well as from state optometric groups which argue that consumers may not be able to distinguish between an online refraction and a comprehensive eye exam.

In its promotional materials for Prescription Check, Warby Parker advises consumers that the test is not a comprehensive eye exam and it isn’t meant to replace visits to an eye doctor.