This type of test uses sound waves to map the structure of the eye. The sound waves travel through your eye, and the echoes form a picture. You'll get numbing eye drops before the exam ...

However, if your vision has changed, they'll recommend a comprehensive eye health exam instead. "During an online vision test, you'll use a smartphone, tablet and/or computer to assess your visual ...

The tests are free, but a prescription costs $20 and is delivered via email within 24 hours. That’s much cheaper than a typical eye exam by an optometrist, which can easily cost well over $100.