Disclosure: I'm a software dev, but my fiancée is an optometrist. There are already machines (called autorefractors) that can try to calculate your prescriptio

Disclosure: I'm a software dev, but my fiancée is an optometrist. There are already machines (called autorefractors) that can try to calculate your prescription. They operate on more complex principles than flipping lenses back and forth. They can provide a good starting point, but sometimes they aren't accurate. A good optometrist can do a lot more than just give you your prescription, though. They should be checking your eyes for signs of disease, and treating things that they find. Seeing an optometrist for a checkup is preventative medicine, like regularly seeing a primary care physician or a dentist.