617 The impact of the spectral composition of long-wavelength ultraviolet A1 and visible light on cutaneous biologic effects

Background & Aim: Recent studies have demonstrated visible light and long-wavelength UVA1 (VL+UVA1, 370-700 nm) to cause erythema in skin synergistically increased pigmentation dark subjects.1, 2 Spectral compositions of VL+UVA1 may further impact these biologic effects. Yet, no phototesting guidelines exist, thus hindering the development reliable sunscreens protective against this part sunlight. The objective study was optimize spectral output as a step standardize assessment protection from VL+UVA1. Methods: Four subjects with Fitzpatrick phototype (SPT) I-III were enrolled prospective pilot study. Two sources used: one 2% another 4% UVA1. match more closely that measured Subjects irradiated each source at 320 J/cm2. Clinical scoring, diffuse reflectance spectroscopy (DRS), colorimetry performed immediately, 24 hours, 7 days, 14 days after irradiation. Results: In all subjects, irradiation VL+ resulted stronger cutaneous response than UVA1, showing an average 4-fold 3-fold increase immediate delayed pigmentation, respectively. These results supported by Δ a*, ITA, DRS relative dyschromia. Conclusion: preliminary indicate composition responses resembling sunlight should be strongly considered when standardizing sunscreen guidelines. This will enable realistic standardized design for evaluation photoprotection within spectrum.