University of Arizona, College of Medicine, Tucson, Arizona, USA.
J Am Acad Dermatol. 2013 May;68(5):817-24. doi: 10.1016/j.jaad.2012.05.034. Epub 2013 Feb 8.
When treating psoriasis, various topical emollients exist that can affect the penetration of ultraviolet radiation in phototherapy. Compared with normal-appearing skin with a reflectance of 4% to 5%, psoriatic skin has higher reflectance as a result of its increased air-to-corneocyte interfaces. Studies have tested the effect of emollients on light penetration by assessing psoriatic plaque clearance, differences in minimal erythema dose, and physical properties of the emollient (eg, monochromatic protection factor and absorbance). Psoriatic plaque clearance was found to improve with serous (thin liquid)-based emollients (eg, Vaseline oil [Unilever, Blackfriars, London, UK], mineral oil, and glycerol), whereas clearance decreased with salicylic acid and viscous-based emollients (eg, petrolatum). Emollients with high ultraviolet absorbance properties increased minimal erythema dose, and those with low absorbance properties decreased minimal erythema dose. Interestingly, when a liquid emollient with a refractive index close to that of normal-appearing skin was applied, there was a net increase in light absorption, or a reduction in reflection that exceeded the emollient's innate ability to absorb light.
在治疗银屑病时，存在各种局部保湿剂，它们会影响光疗中紫外线的穿透。与具有 4%至 5%反射率的正常外观皮肤相比，由于空气与角质形成细胞界面增加，银屑病皮肤具有更高的反射率。研究通过评估银屑病斑块清除率、最小红斑剂量差异以及保湿剂的物理性质（例如，单色保护因子和吸收率）来测试保湿剂对光穿透的影响。发现浆液（稀薄液体）基保湿剂（例如凡士林油[联合利华，伦敦，英国]、矿物油和甘油）可改善银屑病斑块清除率，而水杨酸和粘性基保湿剂（例如凡士林）则降低了清除率。具有高紫外线吸收特性的保湿剂会增加最小红斑剂量，而吸收特性低的保湿剂会降低最小红斑剂量。有趣的是，当应用折射率接近正常外观皮肤的液体保湿剂时，光吸收增加，或者反射减少，超过了保湿剂固有吸收光的能力。
