If you don’t wear contacts or glasses, scheduling an appointment with the eye doctor probably isn’t top on your list of priorities. But needing to get a new prescription for glasses isn’t the only reason you should be visiting the optometrist. Your eyes can reveal much more about your health than you ever imagined and tell you more about your body than just your eyes.

1. Whether you have diabetes. A routine eye exam can detect the early signs of diabetes. Blurry vision, for example, may not just mean you need glasses. It could also be an indicator of type 2 diabetes. Chronically high blood sugar puts a strain on the blood vessels and the disease can manifest in your eyes and even lead to blindness if left untreated.

2. Signs of cancer. When cancer, especially breast cancer, spreads to other parts of the body, it can appear in the eyes. During an exam, eye doctors will look for abnormal masses, lesions, or tumors within the structures of the eyes. Patients who complain of blurry vision, eye pain, or seeing floaters or flashes may have more than problems with their eyes.

3. Risk of heart attack. Retinal vessels can often be the first in the body to show signs of high cholesterol or high blood pressure. They’re also the only blood vessels that can be observed without the use of invasive medical testing like surgery or dyes.

4. Thyroid issues. Your thyroid, the gland at the base of your neck, produces a hormone that regulates your metabolism. If it becomes overactive you may experience blurry vision, dry eyes, double vision, or pain when moving your eyes. If you’re not having the classic symptoms of hyperthyroidism like weight loss, racing heartbeat, shaky hands, or trouble sleeping you may not even know there is a problem.

5. Whether you have an autoimmune condition. Your eyes may feel sandpapery after spending a day staring at your phone or computer, but the discomfort could be due to dry eyes. Dry eyes can be caused by allergies, some medications, or your environment, but they can also be caused by rheumatoid arthritis, Sjogren’s syndrome, and lupus. Dry eyes are easily detected during an eye exam.

Due to these reasons it is crucial to schedule routine eye doctor appointments regardless of whether you have perfect vision. If you found these tips helpful, be sure to share this with your family and friends so they can have healthy eyes too.