Periorbital darkening is common in people with darker skin complexions and is usually multifactorial. It can be as a result of a genetic predisposition (Familial periorbital hyperpigmentation), eczema or allergies and postinflammatory pigmentation. It can also be part of a more diffuse problem of pigmentation. With ageing and loss of periorbital fat , the underlying blood vessels may become visible contributing to the darkening. Laxity or sagging of the lower eyelid can also create a shadow effect.
A good eye cream can help to lighten the appearance of the dark circles by reducing the pigment in the epidermis and firming and lifting the eyelid skin. Contributing medical and dermatological conditions will need to be treated.