You know that it's important to go to your primary care physician for an annual checkup. However, you might not realize that your eyes need routine checkups as well. If you wear contacts or glasses, you should visit the optometrist annually. If you don't need vision aids, you should still see the eye doctor every two years. If you've never been to an optometrist before, you may not know what to expect from the experience. Here are four things you should expect at your next eye exam:

1. Your optometrist will use various machines to examine your eyes.

Part of the purpose of an eye exam is to ensure that your eyes are healthy and functioning normally. Your optometrist will use special machines to test your eyes' ability to focus as well as to examine them closely for potential problems.

2. Your optometrist will test your vision.

Normal human vision is 20/20, but age and genetics may cause your vision to degrade over time. Your optometrist will instruct you to look at an eye chart filled with numbers and letters. They will have you read certain lines to determine how strong your vision is. If your vision isn't perfect, your optometrist may prescribe glasses or contacts to correct it.

3. If you wear contacts, your optometrist will take additional measurements.

Contact lens fitting is an additional component of an eye exam for those who need it. People's eyes have different curvatures, which can change slightly throughout your life. In order to help you get a pair of contacts that fit you well, your optometrist will take additional measurements.

4. Your optometrist may dilate your eyes.

Pupil dilation is a standard part of an eye exam, but it doesn't need to be done every year unless you are at high risk for certain diseases. Your optometrist will put numbing drops in your eyes, which may feel a little itchy, but it's important that you avoid rubbing your eyes. Once the numbing drops have taken effect, your optometrist will use special eye drops to dilate your pupils. This will allow them to see parts of your eyes that are usually not visible in order to check for signs of disease. Pupil dilation isn't painful at all, but you should bring a pair of sunglasses to your eye exam since your eyes will be sensitive to light for a few hours after the procedure.