Dark circles under the eyes are also known as periorbital hyperpigmentation, idiopathic cutaneous hyperchromia of the orbital region, periorbital melanosis or infraorbital pigmentation. Typically, dark circles are bilateral (present on the left and right side) and have a skin tone of medium to dark brown colour, which sometimes extends to the upper nose and forehead. Dark circles are not confined to areas under the eyes and may involve skin surrounding the eyes (periorbital regions). Even though dark circles affect both men and women equally, they are found more prevalent in people with darker complexions. The darkening of skin around the eyes is primarily due to dyspigmentation or hyperpigmentation.
Dark circles are rarely a sign of illness. It is a common condition in otherwise healthy individuals. However, the presence of dark circles under the eyes can be cosmetically unsightly as a person with dark circles may seem exhausted and less energetic. For this reason, many naturally associate dark circles with chronic sleep deprivation and fatigue. While it is true that severe lack of sleep can cause dull and darkened skin under the eyes, there are a number of factors that contribute to the presence of dark circles under eyes. Common contributing factors are ageing, genetics, chronic eye strain, excessive sun exposure and dehydration.
As a person ages, the skin loses its elasticity and fullness due to the reduction of collagen. As a result, the thinning of facial skin causes pigments and blood vessels under the eyes to become more prominent. Moreover, the shadow effect caused by skin laxity and tear troughs formed under the eyes makes dark circles more visible.
There may be a link between genetics and dark circles as certain people naturally produce more pigments in the skin. Research on familial cases of dark circles found that the increase of pigmentations under the eyes usually starts during childhood, and progresses with age to involve the entire periorbital regions.
People who spend long hours staring at the screen of computers or electronic devices can cause significant strain to the eyes. Consequently, the blood vessels around the eyes enlarge, resulting in darkening of skin under the eyes.
Since the skin under the eyes is the thinnest compared to other parts, it is most vulnerable to damage from excessive sun exposure. Ultraviolet rays from the sunlight can easily penetrate and damage skin cells under the eyes, leading to an increase in melanin content in the skin. In addition to the extra melanin pigments, the nature of thin skin makes dark circles under the eyes more visible.
Dehydration can also cause dark circles. As the skin around the eyes is thin and very close to the skull, a lack of fluids in the skin makes blood vessels prominent, resulting in visibly darker skin. Other possible contributing factors of dark circles include drugs, hormones or the extension of pigmentary demarcation lines.
Dark circles may not be a sign of serious illness, but there are several medical conditions that can potentially give rise to dark circles under the eyes. This includes dermal melanocytosis, post-inflammatory hyperpigmentation and periorbital edema.
Dermal melanocytosis occurs when melanocytes (cells that produce melanin) fail to migrate to the base of the epidermis, ending up in the dermis layer. As a result, the skin appears as a blue-grey colour instead of the normal brown skin tone. This condition is benign with no systemic implications.
Post-inflammatory hyperpigmentation is a common sequela of skin inflammation that results in increased melanin content and darkening of the skin. It can be due to allergic reactions, viral rash, fungal infection, contact dermatitis or acne. However, the most common cause of dark circles from post-inflammatory hyperpigmentation is allergic reactions. When an individual has allergic reactions, the skin around the eyes becomes itchy and red, causing the action of scratching and rubbing.
Dark circles alone are usually benign. However, if the eyelids and skin surrounding the eyes are puffy and swollen, then it may indicate an infection of the eyes, dry eyes or kidney diseases. Visit a doctor if one has puffy eyes and dark circles.