We all know high cholesterol is bad for our health, especially our hearts. But did you know it can also affect your eyesight?

"People with high cholesterol have an increased risk for retinal vein occlusion,” Dr. Marc Werner, an ophthalmologist at the Stahl Eye Center in New York City, told FOXNews.com. “Blood has to come into the eye and come out of the eye in a normal situation. When you have high cholesterol, it lines the walls of those blood vessels.”

And this is where the problems begin.

Retinal vein occlusion occurs when there’s a blockage in the blood supply from the retina, which is the nerve layer that lines the back of the eye. The tissue senses light and creates impulses that travel through the optic nerve to the brain.

“If you have blood that has to get out of the eye and it has to go through a narrower and narrower tube — at a certain point it gets too narrow,” Werner said. “The blood flow through that vessel gets slower and slower and eventually a blood clot develops — much the same way if someone had a blocked artery.”

A study featured in the May issue of the Journal of the American Medical Association found that both high blood pressure and high cholesterol appear to increase a person's risk for retinal vein occlusion.

The study, conducted in Ireland, found that people with high blood pressure had more than 3 times the risk of developing the condition, while those with high cholesterol had 2.5 times the risk.

The researchers analyzed 21 previously published studies involving nearly 3,000 people with retinal vein occlusion and 28,000 people without it. What they found was that more than 60 percent of people with RVO had hypertension, compared to 36 percent of people without the eye condition.

High cholesterol levels also played a major role. Researchers found that people with RVO were twice as likely to have high cholesterol as people without the condition.

The authors of the study concluded that “those who treat patients with hypertension, diabetes and high cholesterol should be concerned with the health of the person’s eyes as they are concerned with the health of the person’s cardiovascular system.”

Werner couldn’t agree more. He refers to the eyes as the windows to our health.

“The eye is the only place in the body where you can see blood vessels. So, when I look into someone's eye – I’m not only examining their eye — but I am also getting an indication of their general health,” Werner said.

If the blood vessels in the eyes are narrowed, then it’s a good indication the vessels are also narrowed in the heart, brain and kidneys, he added.

Werner said there are typically no symptoms until it’s too late – when people suffer sudden and significant vision loss — which brings up the point of prevention.

The measures used to prevent other blood vessel disease, such as coronary artery disease, may also decrease the risk of retinal vein occlusion, according to the National Institutes of Health.

The NIH recommends:

— Eating a low-fat diet;

— Regular exercise;

— Losing excess weight.

Properly maintaining diabetes is also another way to prevent this condition, the NIH said on its Web site.

“Things like high blood pressure, diabetes, smoking -- these are all risk factors,” Werner said. “So if you have diabetes, high blood pressure and high cholesterol … you're skating on thin ice with your vision and your health.”