Corneal arcus is a very common diagnosis that optometrists see in their practice every day.
This is a typical eye without cholesterol
Before we get to what corneal arcus is, let's review some basic anatomical structures. There are the upper and lower eyelids/eyelashes. The whitish area of the eye with the blood vessels travelling throughout it is called the conjunctiva. The colored portion of the eye is called the iris. The pupil is the center dark area in the middle of the iris. The cornea is a clear front window of your eye(in front of the iris and pupil).
Corneal arcus is the accumulation of lipids (cholesterol) in the cornea. It looks like a hazy ringlike area that begins in the lower area of the cornea (Figure 2) and can eventually continue 360 degrees around the outside of the cornea (Figure 3). Because the cholesterol initially deposits in an arc-like pattern, it is called arcus.
Cholesterol comes from the food we eat and travels in our bloodstream. Individuals with high cholesterol levels in their blood can be blame genetics and increased consumption of foods with cholesterol. Cholesterol is a large molecule. The cholesterol molecules can leave the blood vessels in the eye (conjunctiva) but because of it's size, it isn't easily reabsorbed by the veins, leading to the accumulation of the cholesterol, or arcus, on the cornea.
Figure 1 shows an eye without corneal arcus. Below are a couple of photographs showing corneal arcus using our biomicroscope cameras we have in our office. The corneal arcus in Figure 2 is very faint and would only be seen with a biomicroscope. Some corneal arcus in Figure 3 can be seen with the naked eye.
So, if I see corneal arcus on the eye, what is my biggest concern? Well, that depends on the patient's age. If a patient is over the age of 50, I am not as concerned as they have had more years for normal cholesterol levels to accumulate on the cornea. The younger the individual with corneal arcus is, the more concerned I am about their blood cholesterol levels. If I see a patient under the age of 50 with corneal arcus, I will write a letter to their medical doctor to rule out high cholesterol. I am also very concerned if the patient with corneal arcus has any known family history of heart disease or if a patient has not had their cholesterol checked over the past 12 months.
Just because I see corneal arcus does not tell me that the individual currently has high cholesterol.
The diagnosis of corneal arcus just tells me that either now or in the past, this patient may have experienced high blood cholesterol levels. Once the cholesterol in trapped in the cornea, it will remain there. Even if a patient improves their cholesterol levels, the arcus will remain.
Because of the typical American diet, I have been diagnosing corneal arcus on younger and younger patients. I see many patients in their 30's and some in their 20's that already have this diagnosis on their eye. Despite what you may think, it is not always someone with a high body fat percentage. Most of my younger patients with corneal arcus look healthy and lean. Typically the younger patients with corneal arcus work jobs where they burn a tremendous number of calories (lawn care, construction work, etc.) but eat unhealthy drive thru meals that are high in fat and cholesterol. These individuals look healthy, but they really aren't.
High cholesterol is a leading cause of heart disease and stroke. Changes in diet and exercise can reduce your cholesterol levels. Medical doctors can also prescribe medication to assist in the reduction of blood cholesterol levels.
Optometrists do more than prescribe contacts and glasses. Optometrists are an integral part of your health care team because they can diagnose and treat most eye diseases and disorders. They also have the education and training to diagnose the ocular manifestations of diseases that affect the entire body, such as high cholesterol, diabetes and high blood pressure.
Ask your optometrist if they see corneal arcus on your eye at your next eye exam. If they diagnose corneal arcus and you don't know what your blood cholesterol levels are, then make an appointment with your medical doctor to have your cholesterol levels evaluated.
This eye has some cholesterol starting to form on the bottom (that little band of white).
This eye has significant cholesterol deposit all the way around.