Dark circles may be associated with a variety of causes. Typically, the main culprits are a combination of pigmentation and age-related skin thinning that allows a shadow to occur.
Dark circles may also be associated with allergies (constant rubbing of the eyes causes the skin to inappropriately thicken and discolor) as well as dilated superficial arteries and veins.
In addition, lack of sleep, fatigue, and iron deficiency anemia may exacerbate under-eye circles. They can be particularly prominent in South Asian skin which has a propensity to hyperpigment.
Possible treatments for dark circles include:
Retinoids and alpha hydroxy acids can help thicken the skin and can be combined with lightening agents to minimize discoloration
Injection of filler
This fills the hollows that develop with age under the eyes thus minimizing dark shadow formation
Laser resurfacing can tighten and thicken the skin and help remove discoloration. Some lasers may also be able to lighten the pigmentation, although great caution and care must be used in darker skin tones to avoid exacerbating the hyper-pigmentation