What do eye doctors see when they dilate eyes?

There are two reasons eye doctors dilate your eyes. The more obvious one is to be able to see better to the back of the eye. A dilated pupil also allows your eye doctor to see further out to the sides and exam the peripheral retina. This is not easily observable through a small pupil. The second reason is to "cycloplege" the eye, i.e. to temporarily paralyze the muscle that changes your focus so as to be able to measure the true, underlying glasses prescription without any possible unconscious interference with its changing during the measurement process.

Written by J. Trevor Woodhams, M.D. - Chief of Surgery, Woodhams Eye Clinic