Treatment of psoriasis with long-wave ultraviolet light

Abstract

Repeated wxposures of 4 by 5-cm sites to erythemogenic doses (20 to 300 joules/sq cm) of long-wave ultraviolet light (UV-A; 320 to 400 nm) led to improvement of the psoriasis vulgaris condition in nine of ten patients treated. Comparison studies showed the therapeutic responses to be similar to that of daily sunburn spectrum (UV-B; 290 to 320 nm) radiation. This finding suggests that the therapeutic response spectrum for psoriasis may parallel the action spectrum for delayed erythema of all portions of the ultraviolet spectrum that pass through psoriatic scale.

A Review of the Use of Tanning Beds as a Dermatological Treatment

“…After 3 initial treatment sessions with standardized doses of 10, 20, and 40 J/cm 2 , symptoms were used to determine future dosing, with all 4 patients clearing with maximum doses of 120 J/cm 2 UVA1 and 3 out of 4 clearing with maximum doses of 80 J/cm 2 . With minimal erythemal dosing of UVA light noted to be 10–100 J/cm 2 [ 16 ] commercial tanning beds could be used to deliver therapeutic doses of UVA light in the treatment of cutaneous T cell lymphoma, though we found no reported cases of this therapeutic approach.…”

“…There may be concern that tanning beds that emit primarily UVA would not be effective for the treatment of psoriasis. While one study found that UVA doses up to 30 J/cm 2 were ineffective for psoriasis, Parrish [ 16 ] found that psoriatic plaques are responsive to erythemogenic doses of either UVA or UVB light [ 16 , 17 ]. The ability of tanning beds to treat psoriasis was compared on the basis of their UVB output, one with a UVB output of 4.6% was compared to another with a lower UVB output (0.7%) in a within-patient comparison technique [ 18 ].…”

“…There were marked and equivalent improvements in Psoriasis Area Severity Index (PASI) scores from baseline in patients treated unilaterally with either lamp with 12 exposures to an equal erythemal dose over a 4-week period. While exposure to either UVA or UVB light can induce clearance of psoriatic plaques, UVA requires more energy (time × power) to reach erythemogenic dosing [ 16 ].…”

UV-A and the skin

“…The only recognized beneficial physical effect of ultraviolet radiation is the promotion of vitamin D synthesis, the action spectrum for which lies within the UV-B range. Repeated UV-A exposure (without 8-methoxypsoralen) led to improvement of psoriasis in a small group of patients (Parrish, 1977) although the cumulative dosages were high (1,800-6,980 J/cm^) involving 13-32 treatments, and clearance was incomplete in some patients, with a marked tendency for relapse, van Weelden, Young & van der Leun (1980) compared the response of psoriasis to UV-B alone, with combined UV-B and UV-A. They found no evidence that addition of UV-A enhanced the therapeutic response to UV-B under the conditions of their study.…”

A Review of Home Phototherapy and Available Home and Handheld Phototherapy Units

“…As early as 1977, it was shown that erythemogenic doses of UVB, even without the concurrent use of topical agents, improve psoriatic lesions. 11 Usually within 6 to 10 weeks, UVB leads to successful clearance of psoriatic lesions when used with or without petrolatum or tar. [12][13][14][15][16] Three to five treatments per week for a total of 5 to 8 weeks (average number of treatment sessions=25) are needed to achieve clearance (n=30) and prolonged remission can be maintained with treatment once every 1 to 5 weeks.…”