Photosensitivity. Classification.

Light is a heterogeneous moiety that is vital for the perception and maintenance of all life on earth. Specific advantages as well as adverse effects are associated with particular wavelengths of light. An etiologic classification of the adverse responses or "photosensitivity disease" is presented as an introduction to this issue.

Potential hazards in phototherapy with ultraviolet radiation arising from variation in dose required to produce erythema.

Phototherapy using 290-320 nm ultraviolet radiation (ultraviolet B) is an effective form of treatment for several skin diseases and is especially useful for psoriasis. Technical advances have made it more economical and convenient to quantify ultraviolet radiation. Ten volunteers received a series of exposures from three ultraviolet B sources to illustrate how variation in the spectral properties of phototherapy devices can lead to unanticipated and potentially severe sunburn reactions. The corresponding minimal erythema dose was then calculated with the use of irradiance data measured with two commercially available photometers. Variation in minimal erythema dose among the three sources tested indicates the need to characterize the emission spectrum of sources and the spectral sensitivity of the photometer used to measure its output.

Photosensitivity diseases related to interior lighting.

The most frequently used source of indoor lighting is the fluorescent tube. Although there are major variations in phosphors, the majority of these lamps are safe, efficient, and economical illuminators. These fluorescent light sources are currently our primary source of visible light; however, they emit small amounts of ultraviolet A light (UVA) as well as a somewhat larger percentage of infrared radiation. Photosensitivity diseases have been reported in each of these three broad wavelength bands. Specific examples include heat urticaria from infrared exposure, contact photosensitivity of the phototoxic type following exposure to dyes and visible light, and two relatively rare but disabling conditions from ultraviolet A exposure--solar urticaria and contact photosensitivity of the photoallergic type (persistent light reaction). During the past five years, eight patients with photosensitivity induced by musk ambrette and UVA have been treated at Columbia-Presbyterian Medical Center; six of these have been severely disabled and satisfy the criteria for persistent light reactors. Fifteen patients with solar urticaria have also been observed. Ten of these had reactions in the UVA range. The clinical and laboratory findings of these two groups of patients were presented.