Surprisingly, lesions on the retina can be a sign of Gardner syndrome, a rare genetic disorder characterized by multiple growths or polyps in the colon, extra teeth and bony tumors of the skull.
"When you have specific types of retinal lesions with scarring that are there for more no reason, especially in a younger person, you should ask for a family history of a colon problem," he said.
The eye is quite literally a "real window" to the rest of the body, according to Dr. Noel Bairey Merz, director of the Women's Heart Center at Cedars Sinai Heart Institute in Los Angeles.
"The vitreous fluid is clear and we can look through the opening in the iris and see the blood vessels quite easily," she said. "They taught us in medical school to look with the opthalmoscope as part of the general exam. Sadly, it's not done by most practitioners and they have lost the skill set."
"We have moved away from common things done in a physical exam to higher-tech things that trump the physical exam," she said.
But just this week, Scottish scientists at University of Edinburgh reported that a simple eye test -- taking a high-definition image of the retina -- could help save the lives of thousands of heart attack patients each year by revealing problems with blood vessels that are indicative of cardiac disease.
Bairey Merz has been part of a similar study in the United States -- the NIH-funded Women's Ischemia Syndrome Evaluation -- hoping that by looking at the microvasulature in the eyes, risk can be identified without invasive procedures.
"We look at arteries and veins in the back of the eye as a predictor of heart disease in women and to a lesser extent men," she said. "The idea is that all of these arteries swim in the same swimming pool and are exposed to the same cholesterol level, sugar level, blood pressure, nutrients or lack thereof, exercise and smoking."
Shirley Kaswinkel, 78, has been part of that study at University of Florida for nine years. "My problem is I have a microartery in my heart that doesn't give me the oxygen I need if I am stressed or tired."
Kaswinkel had seven painful and expensive heart catheterizations before doctors could find a problem, telling her that symptoms were "in my head," she said.
Kaswinkel hopes the study will eventually help other women avoid invasive procedures.
Diagnosing illness through the eye, is nothing new, according to Dr. Marco Zarbin, chief of ophthalmology at the University of Medicine, Dentistry, New Jersey.
"It happens all the time," he said, from rare conditions to diseases like multiple sclerosis, leukemia, brain tumors.
"If you look at your brain, two-thirds of it is dedicated to some aspect of vision," said Zarbin. "It's a big deal."
Eye doctors emphasize that regular exams are important.
Children get their first eye screenings in public school, but after that, opthalmologists advise teens get checked once every one or two years, depending on their health.
After 45, when adults start to lose reading vision, yearly visits are recommended.