A disturbance in the body may sometimes reflect on many different organs in ways that can be quite unexpected. There may be signs evident on or around the eyes that may provide an indication beyond just vision. For example, paleness of the inner surface of the eyelids may be a sign of anemia. Similarly unusual deposits in and around the eye can be a reflection of the blood cholesterol levels.
It is important to first understand what cholesterol is and what it does in the body to then understand the associated dangers of elevated cholesterol levels. Contrary to popular thought, cholesterol is not a ‘bad’ substances. In fact the body needs it for various functions. However, very high levels of cholesterol can be dangerous and even deadly.
Cholesterol is a fat-soluble molecule that has many important functions within the body. For example, cholesterol is an integral part of the membranes that surround the cells and some of the organelles within the cells. Cholesterol is required for the synthesis of bile salts that help in the digestion and absorption of fatty foods within the gut.
A number of key hormones, such as estrogen, progesterone, testosterone and adrenocorticosteroids, are made from cholesterol. Cholesterol also contributes to the waterproof skin-barrier that envelops the body. The cholesterol within the human body comes from both endogenous and exogenous sources.
Sources of Cholesterol
Humans are capable of synthesizing cholesterol within their bodies. Liver is the main organ that is responsible for cholesterol synthesis from the breakdown products of fatty acid metabolism. In addition to endogenous synthesis, humans can also obtain cholesterol through their diet. Certain kinds of meats are especially rich in cholesterol.
Types of Cholesterol
Since cholesterol is a highly fat-soluble molecule, it cannot travel through blood in its free form. In the blood, cholesterol transport occurs within lipoprotein complexes, which are made up of a combination of lipids (triglycerides, phospholipids, and cholesterol) and proteins.
Based on the specific composition, lipoproteins are categorized into the following groups:
- Very low density lipoproteins (abbreviated as VLDL)
- Intermediate density lipoproteins (abbreviated as IDL)
- Low density lipoproteins (abbreviated as LDL)
- High density lipoproteins (abbreviated as HDL)
LDL vs HDL Cholesterol
Low density lipoproteins (LDL) and high density lipoproteins (HDL) are commonly referred to as “bad cholesterol” and “good cholesterol”, respectively. This is due to the association of certain cardiovascular diseases with high LDL concentrations in the blood.
High density lipoproteins sequester excess cholesterol from the tissues and transport them to the liver, where the excess cholesterol is passed out through bile salts. A high HDL concentration in the blood is, therefore, protective against hypercholesterolemia.
On the other hand, low density lipoproteins are sources of cholesterol for the various biological processes in the body. A high LDL concentration in the blood is indicative of high levels of cholesterol in the body.
What causes high cholesterol levels?
Both endogenous and exogenous factors can influence the amount of cholesterol present in the body. Since cholesterol synthesis utilizes the metabolic products of fatty acid breakdown in the body, a high fat diet can increase the amount of cholesterol synthesized in the body by increasing the amount of fatty acid precursors.
An increase in dietary intake of cholesterol itself, however, inhibits endogenous production of cholesterol in the body. An increase in blood cholesterol (technically referred to as hypercholesterolemia) is also seen with low levels of insulin (as in diabetes mellitus) and thyroid hormones (as in hypothyroidism) in the body.
Read more on high blood cholesterol.
Certain liver and kidney diseases can also cause an increase in the cholesterol level. In some individuals, hypercholesterolemia may be genetic (such as in familial hypercholesterolemia). Pregnancy can also cause an increase in the level of cholesterol in the body. Use of certain prescription drugs, such as diuretics, corticosteroids, and anabolic steroids, can also cause an increase in cholesterol levels.
What are xanthelasma and corneal arcus?
An increase in the level of cholesterol within the blood can produce a variety of signs and symptoms. Two such signs of elevated blood cholesterol are xanthelasma and corneal arcus. These eye symptomsdo not usually cause any discomfort. The functions of the eyelids and the eyes are also not affected in most cases.
Xanthelasma refers to a condition in which yellow plaques or deposits are visible around the eyelids. These yellow deposits are soft or semi-solid in consistency, and could be formed due to excess cholesterol. However, it is important to note that the yellow deposits in xanthelasma are not diagnostic of high blood cholesterol.
In xanthelasma, the upper eyelids are more commonly affected than the lower eyelids. However, this condition has a tendency to progress, and the deposits may coalesce and become permanent. Eventually, all four eyelids may become affected, especially on their medial side.
Further blood tests need to be conducted in order to confirm hypercholesterolemia. The yellow deposits around the eyes could also be caused by hyperlipidemia. In some cases, xanthelasma may occur in people with no lipid abnormalities. Moreover, the exact cause of xanthelasma may not be known in every case.
Corneal arcus refers to a condition in which the cornea at the boundary of the iris develops a pale yellow discoloration. This yellow discoloration is mainly caused by crystal deposits of cholesterol. In patients with hypertriglyceridemia, an eye exam may also show the retinal blood vessels as having a pale pink or milky appearance (technically referred to as lipemia retinalis).
If dark rings are seen around the iris, then the condition is most likely due to Wilson’s disease, which is characterized by accumulation of copper. These rings (also known as Kayser-Fleischer rings) should not be mistaken for cholesterol deposits. Corneal arcus is not always associated with a lipid abnormality. This condition can occur in both adults and children.
However, corneal arcus in children is more likely due to hypercholesterolemia. In such cases, the affected child should be investigated for the presence of homozygous familial hypercholesterolemia.
Diagnosis of Cholesterol Eye Deposits
Xanthelasma and corneal arcus are not always caused by hypercholesterolemia or hyperlipidemia. In fact, the signs involving the eyelids and the eyes are not very common in hypercholesterolemia or hyperlipidemia. Therefore, the presence of these signs should warrant further investigations into blood cholesterol and lipid profiles in order to arrive at a definitive diagnosis.
Hypercholesterolemia may also arise as a secondary condition in many disorders. Examples of such conditions include pregnancy, hypothyroidism, anorexia nervosa, cholestatic liver disease, hyperparathyroidism, type II diabetes, nephrotic syndrome, and obesity. Certain prescription drugs, such as diuretics, corticosteroids, and cyclosporine, may also cause hypercholesterolemia as a side effect.
Therefore, the presence of these conditions in an individual who also exhibits signs of xanthelasma or corneal arcus should raise concerns about hypercholesterolemia. Also, the presence of xanthelasma and corneal arcus in children should warrant investigations of hypercholesterolemia. People affected with xanthelasma may also exhibit cholesterol deposits (known as xanthomas) in the skin areas around the elbows, knees, buttocks, and heels.
Treatment for Cholesterol Eye Deposits
Even though the cholesterol deposits around the eyes do not cause any physical discomfort or functional abnormality, one should not try to remove these deposits at home. Secondary infections and scarring may occur if an untrained person tries to remove these deposits. Medical procedures for the removal of these cholesterol deposits include surgical excision, chemical cauterization, laser coblation, cryotherapy and electrodessication. These procedures should only be carried out by a trained medical professional.