A serious vision condition occurring in people with diabetes, diabetic retinopathy is now the leading cause of blindness in people ages 25 to 74 in the U.S. Between 40 and 45 percent of Americans with diabetes have some stage of this retinal disease, but only half know about it. If you have diabetes or a family history of it, it's good to be aware of this condition.

Diabetic retinopathy is caused by progressive damage to the blood vessels in the retina, the light-sensitive tissue lining the back of the eye. Symptoms include blurred vision, having a dark spot in the center of your vision, seeing floaters in your eyes and poor night vision.

Because it is a sight-threatening disorder, the American Academy of Ophthalmology recommends that everyone with diabetes have a comprehensive eye exam once a year based on this screening schedule:

Type 1 diabetes: Within five years of being diagnosed. 

Type 2 diabetes: At the time of diabetes diagnosis. 

Pre-natal: Pregnant women with diabetes should schedule an appointment with their ophthalmologist in the first trimester.

People with diabetes may need the eye exam more than once a year; the frequency of subsequent exams will depend upon the results of the initial examination. An eye exam is usually recommended every one to two years after the initial one.

A comprehensive dilated eye exam may include:

• Visual acuity testing — an eye chart test measuring your ability to see both close and far away
• Tonometry — measures pressure inside the eye
• Pupil dilation — the doctor will place drops onto your eye surface to widen the pupil, providing an ability to examine the retina and optic nerve
• Optical coherence tomography (OCT) — uses light waves to capture photos of your retina

"This retinal exam benefits the patient by identifying critical changes in the eye that may be treatable, and prevent vision loss or even blindness," says Dr. Sathy Bhavan, an ophthalmologist and retina specialist affiliated with Sharp Rees-Stealy Medical Group.

To see if this is a covered benefit, please check with your health insurance. For Medicare members, all people with diabetes who have Part B are covered for a yearly visit. "In fact, dilated retinal eye exams are often considered a medical benefit for people diagnosed with diabetes," says Dr. Jennifer Tuteur, medical director of Sharp Health Plan.

If you have diabetes, protect your vision and don't delay scheduling this vital and valuable eye exam.