Why Do They Dilate my Eyes for an Eye Exam?
Pupil dilation is extremely important because it allows the optometrist to see all the way into the back of the eye. During a normal eye exam, the 
optometrist will use a bright light and a lens to look into the eye, inspecting the health of the cornea, iris, and lens of the eye. However, the bright light causes the pupil to contract, making it difficult for the optometrist to see the back of the eye. When the regular eye exam is done, the optometrist will dilate your pupils so that he or she can completely check your optical health.
The back of the eye hosts the retina, optic nerve, and important blood vessels. When your pupils are dilated, the optometrist will be able to clearly see these parts of the eye and evaluate them. Pupil dilation can reveal general health problems like diabetes, hypertension, and can also catch the signs of glaucoma and cataracts early. For these reasons, optometrists ask their patients to submit to pupil dilation with every eye exam, despite the inconvenience, because they would rather catch serious medical problems early. Healthy kids and adults should have an eye exam, along with pupil dilation, every one to two years, or more frequently as recommended by an optometrist. People who are at high risk for developing optical conditions may need to have their eyes examined more frequently.
