An eye exam typically allows the doctor to screen your eyes and assess overall eye health. He or she may be looking at the blood vessels and nerves in the eye to ensure that the eye is healthy. This allows the doctor to diagnose certain eye conditions that could be a problem for you in the future. A vision exam, on the other hand, tests how well you can see. The vision exam is used to prescribe glasses or contacts in order to get your vision as close to 20/20 as possible.