The size of your pupils fluctuates dozens of time during the day in response to changing light. Assuming you're not exercising in the dark, some other factor is at play if your pupils are dilated during a workout.

During an eye exam, the doctor may use a drop that numbs the surface of the eye. These drops may help the doctor check the eye pressure, or the numbing drops may ease pain and discomfort from foreign bodies, allowing the doctor to carefully examine the eye.

Appearing as the black circle in the center of each eye, your pupils serve as the windows through which light enters your eyes. This function is critical as you are able to see only when light rays reach the retinas deep inside your eyes.

The pupil is the central opening in the iris, the colored part of the eye. Pupil size modulates the amount of light entering the eye. In lighted conditions, the pupil opening is normally relatively small. Pupil-dilating drops temporarily override normal control of the pupil size, causing it to open widely.

A sour stomach describes a condition more commonly known as indigestion. Simple indigestion may be brought on by triggers such as eating certain foods or stress. However, indigestion combined with a numb feeling in the tongue indicates one of several conditions. See your doctor for a diagnosis.

Dilating drops allow doctors a better view into the eye, make it easier to perform eye surgery, and relieve the pain of some eye diseases, like uveitis, an inflammation of the uvea in the eye. Drops used to dilate eyes are called mydriatics.