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To the Editor.—
I want to thank Drs. Tanenbaum, Pathak, and Parrish for their comments. There are, however, certain statements with which I take issue. In the first place, the definition of minimal erythemal dose (MED) refers to erythemogenic irradiation, not to the UVA spectrum. Since determination of MED is a biologic event, it is best measured by the erythema response to irradiation that simulates the natural environment—a combination of UVA and UVB in this instance. In our study, we utilized a constant dose that was shown to be twice the normal MED in our laboratory, with the use of an instrument that has been shown to emit ultraviolet (UV) radiation in a continuous spectrum resembling midday summer sunlight (J Invest Dermatol 53:192,1969). The authors of the letter refer to "MedB"—we never measure MED to a narrow band, only to a broad band encompassing UVA and UVB.It is necessary
Stern WK, Kihiczak G. Ultraviolet Light Therapy for Psoriasis-Reply. Arch Dermatol. 1975;111(3):397. doi:10.1001/archderm.1975.01630150117024