‘Skin pore’ is a term used by lay people and in the field of cosmetology. It remains misleading when it is not clearly defined. Indeed, lay people use it with at least 3 different meanings. Basically, invisible pores represent the openings of the sweat gland apparatus. By contrast, the visible pores represent enlarged empty funnel-shaped or cylindrical horny impacted openings of pilosebaceous follicles. This review describes some of the current objective methods used to describe skin pores.

Background: Several instrumental methods can indirectly assess some specific aspects of cutaneous irritation at the level of the stratum corneum (SC). Objective: There is a need for developing more sensitive approaches in this field. Methods: We assessed a recently introduced innovative tool (SkinChip^®) based on capacitive pixel-sensing technology in its potential to detect early discrete manifestations of skin irritation. The sensor generates a detailed non-optical picture corresponding to a capacitance map of the skin surface reaching 50 µm pixel resolution. Some topographical details can be easily disclosed and the SC hydration as well. Two surfactant solutions were tested on volunteers. These solutions were applied under test patches for 2 days on the volar forearms. Clinical and SkinChip assessments were performed 3 h after removing the patch. Results: The generated images allowed a precise observation of skin irritation which appeared as a two-step process. Early changes consisted of darker pixels corresponding to overhydrated swollen corneocytes at the irritated sites. Two days later, the same area appeared as white pixels, indicating the loss of corneocyte hydration. Conclusion: The SkinChip device appears to be a very sensitive tool for detecting the early steps of surfactant-induced skin irritation affecting the SC.

Surfactant-based skin care products can induce minimal to severer alterations of the human stratum corneum (SC). These changes can be conveniently assessed using electrometric devices. Four different surfactant-based solutions were applied to the forearms of 10 healthy volunteers following a soap chamber test method. The 2-day patch testing was followed by a 2-week follow-up. Clinical and instrumental assessments were performed at 7 time points. Data generated by the Corneometer^® CM820, the Dermalab Moisture Module^® and the Nova Dermal Phase Meter^® (DPM) 9003 were compared. The significant differences between the product aggressiveness to the SC were similarly disclosed by the Corneometer and the Dermalab Moisture Module. The ranking of product aggressiveness given by the 3 devices 5 days after patch removal was similar to that given by the clinical assessment of erythema. A high level of correlation was found between the values yielded by the immediate and continuous mode assessments using the Dermalab Moisture Module with the pin probe, while the correlation was weaker with the Nova DPM. This finding may be related to the fact that the Nova DPM is influenced by the accumulation of the transepidermal water loss in the continuous mode assessment while there is no significant occlusion effect of the Dermalab Moisture pin probe that is more representative of the initial level of SC hydration. In conclusion, the Corneometer and the Dermalab Moisture Module respond similarly to changes in the SC content. This finding is different from some previous reports.

Background: The stratum corneum (SC) structure and functions are altered by surfactants. Enhancing the repair mechanisms is a goal for some skin care formulations. Aim: To design an experimental procedure allowing the discrimination of repair efficacy for topical products applied to threatened SC. Method: Controlled SC strippings followed by repeated forearm soak sessions in surfactant solutions were used to compromise the SC barrier function in 20 volunteers. Two test formulations were compared. They were applied twice daily for 2 weeks before initiating the SC damages, and for the next 2 weeks while sustaining the procedure of soak sessions. Daily assessments involved objective measurements of parameters including transepidermal water loss, the value of the passive sustainable SC hydration and the epidermal turnover rate using the dihydroxyacetone test. Result: The experimental procedure allowed to clearly distinguish the differences in the kinetics of SC repair between the topical formulations. In the present study design, the repair of the barrier function mirrored the SC renewal. Conclusion: The present experimental design slows down the repair rate of the SC barrier function. Thus, it increases the sensitivity of biometrological measurements assessing some of the major SC properties. It also better mimics the common in vivo situation experienced by subjects chronically exposed to irritant xenobiotics.

Background: Acne is a multifactorial disease exhibiting distinct clinical presentations. Among them, the catamenial type is a matter of concern for young women. Some oral contraceptives may help without, however, clearing the skin condition. Aim:The present open study aimed at evaluating the effect of overnight applications of a paste made of petrolatum, 15% zinc oxide and 0.25% miconazole nitrate. Method: The split-face trial was conducted in 35 women. A non-medicated cream was used as control. Clinical evaluations and biometrological assessments on cyanoacrylate follicular biopsies were performed monthly for 3 months. Comedometry and the density in autofluorescent follicular casts were used as analytical parameters. In addition, the five most severe cases at inclusion were tested at the completion of the study for follicular bacterial viability using dual flow cytometry.