The Effectiveness Of UVA1 Irradiation In The Treatment Of Skin Conditions With Altered Dermal Matrix: A Controlled, Cross-Over Study

Ultraviolet rays from the sun that reach the earth surface are divided into shorter wavelength, hence high energy, UVB (290-320nm) and longer wavelength, hence low energy UVA (320-400nm). The wavelengths of light that cause sunburn and are associated with skin cancer causation is the high energy UVB. UVA wavelengths can be further divided into relatively shorter wavelength, hence higher energy UVA2 (320-340nm) and longer wavelength, lower energy UVA1 (340-400nm). Phototherapy light boxes used in our clinic for the treatment of psoriasis, atopic dermatitis, and pruritus, as well as those used in tanning salons emit both UVB and UVA wavelengths of light. The advantages of using UVA1 light source in the treatment of skin conditions are 1) lack of skin cancer and sunburn causing rays (UVB/UVA2) and 2) as a consequence, the ability to treat patients more safely.

Keloid, scleroderma, acne keloidalis nuchae, and burn scars are all characterized by collagenous thickening of the skin resulting in superficial and deep cutaneous sclerosis. Treatments for these disabling conditions are inadequate at present. Recently, in non-controlled studies, UVA1 was shown to induce improvement in patients with scleroderma, granuloma annulare and urticaria pigmentosa (1-3). The mode of action of UVA1 treatment is not completely understood, however, local immuno-modulation appears to be important (4). UVA1 has also been shown to stimulate collagenase activity in a dose dependent manner in the dermis (5,6). We postulate, therefore, that UVA1 in appropriate doses can improve these fibrosing skin conditions safely through collagenase-mediated removal of excess dermal collagen.