A yearly dilated eye exam could protect more than just your vision. Problems spotted in the eye are often the first warning of disease elsewhere in the body. Fortunately, eye doctors may be the first to detect several life-threatening conditions.

“We always look for signs of eye disease,” says Katherine Hu, MD, an ophthalmologist at John A. Moran Eye Center. “But subtle, early damage to tiny blood vessels in your eyes can also reveal important clues about what’s going on in your whole body—particularly the brain and heart. Since many diseases have no early symptoms, you could be at risk and not know it.”

That’s one crucial reason why every adult should get a comprehensive eye exam—one in which your eyes are dilated—by age 40 and every year or two after age 65.

A dilated eye exam is simple and painless. Your eye doctor will give you some drops to dilate or widen your pupil. This allows the physician to look at the structures in the back of your eye, including the retina, macula, and optic nerve.

Although numerous conditions beyond eye disease can show up during a dilated eye exam, here are six of the most common: