Change in ultraviolet (UV) transmission following the application of vaseline to non-irradiated and UVB-exposed split skin

Background Topical preparations such as emollients used in combination with phototherapy can interfere with such treatment. Objectives This study was performed to investigate the impact of vaseline o n the ultraviolet (UV) transmission of non-irradiated split skin and on spl it skin previously exposed to UVB radiation. Methods Split-skin specimens were obtained from 20 patients. In each case, one sample was taken from an area of non-irradiated skin, while the second was taken from an area that had been previously exposed to UVB. The transmi ssion was spectrophotometrically measured with split skin placed in special ly designed quartz glass cuvettes before and after the application of two d ifferent amounts of vaseline (2 . 5 and 17 . 5 mg cm(-2)). Results Application of vaseline to skin previously exposed to UVB caused si gnificant (P < 0 . 0001) changes in UV transmission in certain wavelength r anges. In the UVA range, a greater increase in transmission was achieved wi th 2 . 5 mg cm(-2) vaseline, whereas in the UVB range, a greater increase w as achieved with 17 . 5 mg cm(-2) vaseline. The thicker the layer of vaseli ne applied, the lower was the difference in transmission between non-irradi ated split skin and UVB-exposed split skin. Conclusions Application of the correct amount of vaseline can enhance trans mission in either the UVA or UVB range, and would enable dose reduction dur ing a course of phototherapy.