Light-emitting diode phototherapy in dermatological practice

Abstract

Phototherapy in its broadest sense means any kind of treatment (from the Greek therapeia 'curing, healing,' from therapeuein 'to cure, treat.') with any kind of light (from the Greek phos, photos 'light'). The modern accepted definition of phototherapy, however, has become accepted as: the use of low incident levels of light energy to achieve an athermal and atraumatic, but clinically useful, effect in tissue. Under its basic original definition, phototherapy is an ancient art because the oldest light source in the world is the sun, and therapy with sunlight, or heliotherapy, has been in use for over 4,000 years with the earliest recorded use being by the Ancient Egyptians.1 They would treat what was probably vitiligo by rubbing the affected area with a crushed herb similar to parsley, then expose the treated area to sunlight. The photosensitizing properties of the parsley caused an intense photoreaction in the skin leading to a very nasty sunburn, which in turn hopefully led to the appearance of postinflammatory secondary hyperpigmentation, or 'suntan' thereby repigmenting the depigmented area. In their turn the Ancient Greeks and Romans used the healing power of the sun, and it was still being actively used in Europe in the eighteenth, nineteenth and early twentieth century, particularly red light therapy carried out with the patient placed in a room with red-tinted windows. One famous patient was King George III of Great Britain and Northern Ireland who ruled from 1760 to 1801, popularly though erroneously known as 'Mad King George'. We now strongly suspect that he was actually suffering from the blood disease porphyria, so being shut in a room with red-draped walls and red tinted windows to treat his depression probably only served to make him even more mad, since porphyria is often associated with severe photosensitivity! Entities treated this way included the eruptive skin lesions of rubella and rubeola, and even 'melancholia', as was the case with King George III, now recognised as clinical depression. Hippocrates, the Father of Medicine, certainly concurred with the latter application some two millennia before King George: Hippocrates prescribed sunlight for depressive patients and believed that the Greeks were more naturally cheerier than their northern neighbors because of the greater exposure to the sun.