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Background: Polarized light photography has been used to selectively differentiate surface from subsurface features of photoaged skin. Objective: Our purpose was to compare acne assessments obtained from clinical evaluations with assessments from photographs obtained with flash photography and with perpendicular polarized light photography. Methods: Assessments of acne with the Cunliffe scale were made of 32 subjects. Retrospective evaluations of standard and perpendicular polarized light photographs were made in a blinded fashion by a panel of evaluators. Results: Visualization of inflammatory acne lesions was enhanced with perpendicular polarized light photography, with clear delineation of erythematous borders. Acne assessments with the use of a Cunliffe scale were significantly higher ( p = 0.001) from perpendicular polarized light photographs than for clinical evaluations. Conclusion: Polarized light photography enhances visualization of inflammatory acne lesions in a manner not possible with conventional flash photographs, permitting accurate evaluation of the extent of disease and the effectiveness of therapy. (J Am Acad Dermatol 1997;37:948-52.)

Chronic exposure to a weak irritant leads to inflammatory changes which may be followed by pigmentary changes and accommodation. The inflammatory responses to acute exposure to an irritant have been extensively studied. This study investigated quantitatively the inflammatory reactions produced in photodamaged skin with chronic application of a weak chemical irritant (tretinoin cream 0.025%) over a period of 9 months (36 weeks). Forty-eight subjects with moderately to severely photodamaged skin were enrolled in a 36-week, double-blind placebo-controlled study. Tretinoin cream was applied nightly on the distal two thirds of one dorsal forearm and placebo on the other. The proximal third of each dorsal forearm received no treatment and served as control. Clinical assessments and diffuse reflectance measurements were made at 7 time points during treatment. Apparent concentrations of oxyhemoglobin (HbO2), deoxyhemoglo-bin (Hb) and melanin were estimated by analysis of the diffuse reflectance spectra. No changes were observed in the apparent H bO2or the Hb concentration of the placebo-treated or control sites, thus establishing a reliable baseline. The apparent HbO2 concentration of the tretinoin-treated sites increased significantly from baseline to a maximum at 12-18 weeks of treatment, then returned to baseline with continued applications. The changes in HbO2 concentration agreed closely with clinical assessments of erythema. The apparent melanin concentration, corresponding to diffuse hyperpigmentation, showed a large seasonal decrease in both the control and the treated sites, with an additional decrease in the treated sites between 12 and 18 weeks. Erythema appeared after repeated applications and eventually resolved under continuous treatment. The maximum decrease in hyperpigmentation occurred simultaneously with the maximum increase in erythema.

Background: Quantification of acne remains a challenge. It may be difficult to identify lesions by standard flash photography. Previous studies have shown that foci of light in fluorescence photographs correspond to high protoporphyrin IX production by Propionibacterium acnes in open comedones, follicles, and inflammatory lesions. Objective: Our purpose was to study the utility of fluorescence photography for evaluation of acne. Methods: Forty subjects with mild to moderate acne vulgaris were randomly selected to apply either clindamycin 1% topical solution or vehicle twice daily. Counts of acne lesions and flash and fluorescence photographs were obtained at baseline, and at 4, 8, and 12 weeks. Results: At 12 weeks, the treatment group had a larger percentage change in open comedones, less fluorescence in all areas assessed, and a larger percent decrease in fluorescence than the vehicle group. Conclusion: Fluorescence photography appears to be a useful tool to chart the course of acne treatment.

Background: The clinical characteristics of photodamaged skin, such as coarse and fine wrinkling, sallowness, hyperpigmentation, tactile roughness, laxity, and erytherma, are not accurately evaluable from photographic records. Objective: The purpose of this study was to develop accurate and reproducible photographic techniques that generate an evaluable record of the characteristics of photodamaged skin. Methods: The method used involved illumination and photography through polarizing filters (polarized light photography). Results: Polarized light photography generates images that selectively enhance either the surface features or the subsurface features of the skin, providing an accurate and evaluable record for evaluation of photodamaged skin. Conclusion: Polarized light photography, when coupled with precise framing and mapping, yields an accurate and evaluable record of photodamaged skin.