SAN ANTONIO - More people are starting to use online vision tests to get eyewear for themselves.

It's called Opternative. But just how safe is it?

To take the test you'll need three things: Your old prescription, your current eyewear, and a smartphone, which acts as a remote control.

Just like a traditional eye exam, it has you cover each eye and go through each instruction. Using your cell phone to run the test takes only 15 minutes your exam is complete.

KENS 5 Jeremy Baker wanted to compare the mobile test to a traditional eye exam.

Baker went to Vision Source in Stone Oak.

He said that exam took a little longer, but they did a lot more, including testing for depth perception, checking your eye muscles, and signs of glaucoma or macular degeneration.

In-person, tests examine the health of the eyes, which online vision tests can't do.

"There are sight-threatening conditions like glaucoma. Glaucoma is a disease which you won't feel, and you won't know you have it until it's too late, " Dr. Monica Allison, an optometrist with Vision Source said.

Opternative does remind users that it's not a comprehensive eye exam and you should still see your eye doctor for health checks every two years.

Opternative costs $40 for glasses or contacts and $60 for both.

"I don't think you're saving money by doing it because most people are insured, and if you think you are saving money you are not really, You're not getting the whole picture, you're getting part of it, " Dr. Allison said.

Opternative boasts about its convenience.

"Opternative provides accessibility and convenience, unlike any other vision testing service. No longer are you required to make an appointment to obtain a vision test, as you can start at a time that is convenient, and at the location that is convenient," Co-founder Steven Lee said.

So whether you use an online test or not, both Opternative and Dr. Allison agree that you need to see your eye doctor regularly to make sure your eyes are healthy.