INFLUENCE OF UVA ON THE ERYTHEMATOGENIC AND THERAPEUTIC EFFECTS OF UVB IRRADIATION IN PSORIASIS - PHOTOAUGMENTATION EFFECTS

[摘要] Effect of repeated exposure to an additive dose of long UV (UVA) radiation on the erythemogenic and therapeutic effects of middle UV (UVB) irradiation was investigated in 8 patients with psoriasis. Back surface of these patients was divided into 2 parts; 1 received only UVB irradiation 4 times wk, the other received UVA + UVB. UVB was provided by Philips TL-12 lamps and UVA by glass-filtered Philips TL-09 lamps. UVA was held constantly at 10 J/cm2 and UVB was increased. Erythemogenic effects of UVA + UVB and UVB alone were evaluated by 4 test during treatment to determine minimal erythema dose (MED). Test 1 (at start of therapy) showed a photoaugmentative effect which was no longer apparent in test 3 (3rd wk). Test 3 showed a reversal of ratios of MED of sites irradiated with UVA + UVB and UVB (MED A+B/MED B). This was ascribed to the marked pigmentation which appeared after repeated irradiation with UVA + UVB combination. Comparison of improvement of psoriasis showed no distinct differences between UVA + UVB irradiation and UVB alone but the former had the cosmetic advantage of giving pleasing tan.