You might think your vision is 20/20 or that your eyes are healthy, but visiting your eye care professional for a comprehensive dilated eye exam is the only way to really know. During a comprehensive dilated eye exam, your eye care professional places drops in your eyes to dilate, or widen the pupil to allow more light to enter the eye; getting a good look at the back of the eyes for any signs of damage or disease. Many common eye diseases such as glaucoma, diabetic eye disease and age-related macular degeneration often have no warning signs. A dilated eye exam is the only way to detect these diseases in their early stages before vision loss occurs.