29 Jul 2019

High blood cholesterol levels have observable signs in the eyes. High serum cholesterol levels can often lead to various cardiovascular problems, which are sometimes referred to as high cholesterol symptoms.

High serum cholesterol can remain silent without any associated diseases, and individuals may feel healthy without realizing they are at risk. For this reason, individuals over the age of 20 are recommended to have their serum cholesterol levels measured every 5 years.

However, high cholesterol levels can accumulate in various layers of the eyes, becoming visible without causing any related diseases. These signs, detected by an eye doctor during an examination, can help identify high serum cholesterol levels that are progressing silently, before cholesterol-related diseases emerge.

Cholesterol deposits in the eyes can be observed in the eyelids, in the transparent front layer of the eye called the cornea, and in the retina layer, which contains the nerves responsible for vision, located at the back of the eye.

The appearance of yellowish cholesterol plaques on the eyelids is known as xanthelasma. Xanthelasma is a common condition that often affects both eyelids symmetrically. It is typically seen in individuals over middle age. When xanthelasma occurs, especially in young adults, it should be considered associated with high serum cholesterol levels. Xanthelasma is not a malignant lesion, and it does not cause clinical symptoms or affect visual function. Treatment, if desired for cosmetic reasons, involves the removal of these lesions under local anesthesia. Genetics play a role in its formation, and even if serum cholesterol levels are controlled, recurrence may occur.

The cornea is the transparent front layer of the eye, shaped like a curved watch glass. The cornea acts like a window for incoming light rays. As age advances, the appearance of a circular, open grayish-yellow ring (arcus senilis) around the cornea’s edge is considered normal. However, the presence of this condition in individuals under the age of 45 (juvenil arcus senilis) is an indicator of high serum cholesterol levels. In cases where serum cholesterol levels are high, cholesterol begins to accumulate in the deeper layers of the cornea.

Additionally, in congenital diseases related to genetic corneal lipid metabolism disorders, bright oval deposits resembling crystalline particles start to accumulate in the middle part of the transparent cornea layer in individuals in their twenties. In approximately half of these patients, serum cholesterol levels are high, while in the other half, serum cholesterol levels are within the normal range. It is believed that the primary cause of these lipid deposits is the disturbance of lipid metabolism in the cornea layer rather than high serum cholesterol levels. These lipid particles mainly contain phospholipids and cholesterol. Because they settle in the center of the cornea, they cause increasing visual blurriness with age. Treatment involves the removal of these fat particles from the corneal surface using excimer laser.

The layer at the back of the eye, where the light-sensitive special cells responsible for vision and the delicate blood vessels that nourish the eye are located, is called the retina. By dilating the pupil, this layer can be examined. The appearance of the delicate blood vessels behind the eye provides information about the overall condition of the body’s vascular system. High serum cholesterol levels can lead to the accumulation of cholesterol in the walls of these delicate blood vessels in the retina. During eye examinations, the presence of cholesterol plaques in the vessel walls and their effect on blood flow can be observed. When a cholesterol plaque completely obstructs a blood vessel, it can result in a cessation of blood flow in the eye, leading to vision loss. Once the plaque shifts from its place, blood flow is restored, and vision improves. When left undiagnosed, this situation can manifest as recurring episodes of transient vision loss. When cholesterol accumulation is observed in the blood vessels behind the eye, it is assumed that similar cholesterol buildup may be present in other delicate vessels throughout the body, such as coronary arteries in the heart and small vessels in the brain, leading to circulatory problems.