got my eyes check up after 2 yrs my question are?

Normally, someone in the office will use a lensometer to measure the power in your old glasses. We generally use this as a starting point for your new prescription. We do tests to see if what you need now differs from that. Sometimes, even if there appears to be a change, we will still prescribe the same thing. For example, in a person in her twenties or thirties, I will seldom decrease the amount of myopic prescription even if her tests show that it should work. If I prescribe the same thing, I always try to be careful to inform the patient that this is the case so they can make choices about buying glasses appropriately. I also try to review any complaints that they had about their vision that may have prompted the eye exam. We don't expect much change in prescription between 20 and 40.

The doctor knows your prescription from performing a complete eye exam.

They determine how light moves through your cornea with either a computerized machine or by shining a light in your eyes.

They also sit you at a piece of equipment and have you read letters projected onto the wall, and change the lenses that you see through, asking, "which is better, one or two?"

The results of the tests give them the prescription for your best vision.