A new start-up is hoping you’ll be willing to test and treat impaired vision from home.

Opternative will take you through a series of eye exams on your desktop or laptop computer by instructing you to sit a sufficient distance away and navigate the site using your smartphone. While the test is free, you can opt to pay $40 for one of the site’s ophthalmologists to review the results and mail you a prescription for corrective lenses that can be filled anywhere.

While a clever and convenient idea, the notion of diagnosing eye problems virtually has already drawn criticism. According to NPR, health professionals are concerned that individuals treated online will miss out on a key part of in-person evaluations: looking for signs of glaucoma, diabetes, cataracts, and other conditions that can threaten a person’s vision. Indiana, Georgia, and South Carolina have outlawed prescriptions stemming from online tests; other states may follow suit. Last fall, the American Optometric Association filed a complaint against Opternative with the FDA. 

Opternative has countered that optometrists are lobbying against the service because it could cut into their own business and offers what it claims is clinical evidence that the online tests are comparable to traditional refractive exams.

The bottom line? If you just want to update an existing prescription, the American Academy of Ophthalmology says an online exam may be sufficient—but it should never replace a face-to-face (or eye-to-eye) checkup with a local doctor.

[h/t NPR]