NEW YORK—New details about Warby Parker’s new Prescription Check service are emerging, following VMail’s report yesterday that the click and brick retailer will be launching the mobile refraction service on a limited basis this summer.

Prescription Check uses a proprietary vision testing method which requires only an iPhone, an app and a computer. The test, which takes 20 minutes, consists of three separate vision tests—Landolt C, Fan Chart and Duochrome—all of which are commonly used in conventional eye exams. Patients view the test images on a computer screen.

Warby Parker worked for two years to develop a simple but effective way to ensure the accuracy of the tests, VMail has learned. Patients place a credit card or driver's license in the corner of the computer screen and point their phone's camera at it.

The smartphone app determines the computer screen size, enables the test images to be displayed at the correct size and tells the patient where to stand. Patients then swipe their phone in the direction of the images. Warby Parker was granted a patent for the measurement method last year.

To utilize Prescription Check, patients must already be Warby Parker customers. Before taking the tests, patients must answer questions about their vision and eligibility. Patients then send the test results to either an independent optometrist or ophthalmologist who reviews the data and checks it against the patient’s current prescription, which they can access through Warby Parker’s database.

The eye doctor then issues a new prescription, if needed, within 24 hours. If the doctor determines that further evaluation is needed, a referral to an eye doctor is provided. Anyone with a history of eye disease or risk factors are not eligible to participate. Patients self-report their eye health history as part of the screening process.

The Prescription Check app works with only with an iPhone, and is available exclusively through the iTunes store.

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 participate and must have had a comprehensive eye exam within the last five years.

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.

Online refraction 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.

The American Optometric Association was quick to condemn Prescription Check as well as the widely used online vision test marketed by Opternative, which pioneered the technology. The organization issued a statement yesterday, in which it said, “When patients rely on an app for an eyeglass or contact lens prescription, they can receive inaccurate or misleading information and potentially delay essential sight saving treatment.

“An online eye test does not completely cover any one of the 12 components of a regular in-person, comprehensive eye exam. National agencies, including the National Eye Institute and the Centers for Disease Control and Prevention, agree that a comprehensive eye examination is the only way to know whether your eyes and vision are healthy.

“And last year, the National Academies of Science, Engineering and Medicine issued a national call to action to make eye health a priority. Touting virtual technologies that are not proven and subvert care sets us all back,” the statement from AOA said.

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