Understanding effects of topical ingredients on electrical measurement of skin hydration

Photobiomodulation Reduces Periocular Wrinkle Volume by 30%: A Randomized Controlled Trial

Objective: This study aimed to evaluate red and amber light-emitting diode protocols for facial rejuvenation at the same light dose. Background: The demand for minimally invasive cosmetic procedures to address skin aging has grown throughout the world. In vitro red and amber photobiomodulation (PBM) has been shown to improve collagen synthesis. Meanwhile, red PBM has already been studied in clinical trials; however, a comparison of the use of different wavelengths at the same light dose to reduce periocular wrinkles has not yet been performed. Methods: This split-face, randomized clinical trial recruited 137 women (40-65 years old) presenting with skin phototypes II-IV and Glogau photoaging scale types II-IV. The individuals received 10 sessions for 4 weeks of red (660 nm) and amber (590 nm) PBM (3.8 J/cm²), one at each side of the face. The outcomes, measured before and after the treatments, were the periocular wrinkle volume measured by VisioFace^® RD equipment; hydration measured by the Corneometer CM 825; skin elasticity measured by the Cutometer Dual MPA 580; and quality of life determined by adapted versions of validated questionnaires [Melasma Quality of Life Scale-Brazilian Portuguese (MelasQoL-BP) and Skindex-29]. Results: There was a significant reduction in wrinkle volume after red (31.6%) and amber (29.9%) PBM. None of the treatments improved skin hydration and viscoelasticity. Both questionnaires showed improvements in participants' quality of life. Conclusions: PBM, both at red and amber wavelengths, is an effective tool for rejuvenation, producing a 30% wrinkle volume reduction. The technique has strong potential in patients with diabetes or those presenting with keloids, conditions for which highly inflammatory rejuvenating procedures are not indicated. Clinical trial registration number: REBEC-6YFCBM.

A comprehensive comparison of facial skin hydration based on capacitance and conductance measurements in Chinese women

OBJECTIVES

The aim of this study was to compare the data of conductance and capacitance measurements of facial skin hydration and to evaluate and discuss the advantages and disadvantages of the different approaches.

METHODS

We measured skin capacitance (Corneometer® CM 825) and skin conductance (Skicon-200EX®) on 30 pre-defined facial sites of 125 Chinese women, resulting in 3750 readings per device. The data were analysed and compared, and continuous colour maps were generated on a 3D avatar for capacitance, conductance, relative difference (Δ%) and correlation (R-value) by interpolating between the individual readings and converting the values to colours. This visualization allows a better interpretation of the results.

RESULTS

The complexity of facial skin hydration is revealed by this approach. The similarities and discrepancies in the facial hydration maps are clearly apparent. Due to the superiority of the Skicon in measuring high hydration levels, differences in skin hydration were evident on the forehead compared with the Corneometer maps, which may be related to the more superficial measurement of the Skicon within the stratum corneum. Conversely, a greater understanding of the complexity of facial skin hydration in the nasolabial fold was obvious when using the Corneometer. The best congruence between the instruments was found at two specific but separated facial areas, one around the inner eye region and the other one on a line between the nasolabial sulcus and the oblique, lateral jaw. Interestingly, the data were not normally distributed for both instruments and they had opposite skews. All facial clusters were statistically different from each other (p < 0.001), except the cheek and jaw for the Skicon. Larger than expected percentage coefficients of variance were found for the Corneometer on some facial sites that might be explainable by differences in stratum corneum physiology and biochemistry. Corneometer values of 48 AU and Skicon values of 132 μS were taken as the cutoff for normally hydrated facial skin.

CONCLUSIONS

Both devices have their advantages and disadvantages suggesting that bio-instrumental measurement of skin hydration is actually more complicated than commonly thought and that the different facial zones and the use of multiple instrumentation have not been adequately considered.

Skin Quality - A Holistic 360° View: Consensus Results

Introduction

Skin quality is an important component of human attractiveness. To date, there are no standardized criteria for good skin quality. To establish a consensus for good skin quality parameters and measurement and treatment options, a virtual skin quality advisory board consisting of a global panel of highly experienced aesthetic dermatologists/aesthetic physicians was convened.

Methods

A total of 10 dermatologists/aesthetic physicians served on the advisory board. A modified version of the Delphi method was used to arrive at consensus. Members accessed an online platform to review statements on skin quality criteria from their peers, including treatment and measurement options, and voted to indicate whether they agreed or disagreed. Statements that did not have agreement were modified and the members voted again. Consensus was defined as: strong consensus = greater than 95% agreement; consensus = 75% to 95% agreement; majority consent = 50% to 75% agreement; no consensus = less than 50% agreement.

Results

There was strong consensus that good skin quality is defined as healthy, youthful in appearance (appearing younger than a person's chronological age), undamaged skin and that skin quality can be described across all ethnicities by four emergent perceptual categories (EPCs): skin tone evenness, skin surface evenness, skin firmness, and skin glow. The EPCs can be affected by multiple tissue layers (ie, skin surface quality can stem from and be impacted by deep structures or tissues). This means that topical approaches may not be sufficient. Instead, improving skin quality EPCs can require a multilayer treatment strategy.

Conclusion

This global advisory board established strong consensus that skin quality can be described by four EPCs, which can help clinicians determine the appropriate treatment option(s) and the tissue or skin layer(s) to address. Skin quality is important to human health and wellbeing and patients' perception for the need for aesthetic treatment.

Multi parametric biophysical assessment of treatment effects on xerotic skin

Background

Topical moisturizing products are widely used to alleviate the problems associated with xerotic skin. Their use affects many properties of the stratum corneum (SC) in a complex and interrelated manner. The range of measurement techniques available to the researcher has increased in recent years. However, few studies have looked for correlations between the different techniques for assessing how aspects of xerotic skin change over time as a result of topical moisturizer usage.

Objectives

A 3‐week in vivo study using an oil‐in‐water based moisturizing product and an untreated site was conducted to determine the clinical significance of and any correlations between a range of different approaches for the measurement of skin lipid content and also skin hydration and visual grading of dry skin.

Methods

A range of traditional and more recently developed skin measurement techniques have been used to examine a variety of SC properties in normal and xerotic skin during topical moisturizer usage.

Results

In vivo confocal Raman spectroscopy and analysis of SC lipids from tape strips both showed an increase in SC lipid level and organization after 3 weeks of moisturizer usage on xerotic skin. Hydration, measured both optically and electrically, also increased and skin barrier function improved, with strong correlations between the different measures of dryness being observed.

Conclusions

Strong correlations were observed between the skin measurements for lipid assessment and skin hydration with regard to the assessment of xerotic skin, providing valuable new information for future in vivo clinical research into dry and atopic skin.

Keywords

biophysical assessment, skin barrier, skin hydration, topical moisturizers, Xerosis

Measurement of dermal water content using a multi-wavelength optical sensor

Skin hydration is crucial for overall skin health. Maintaining skin hydration levels preserves skin integrity and prevents tissue damage which can lead to several debilitating conditions. Moreover, continuous monitoring of skin hydration can contribute to the diagnosis or management of serious diseases. For instance, sugar imbalance in diabetes mellitus and kidney disease can lead to the loss of bodily fluids and cause dry skin. Therefore, continuous, accurate and non-intrusive monitoring of skin hydration would present a remarkable opportunity for maintaining overall health and wellbeing. There are various techniques to assess skin hydration. Electrical based Corneometers are currently the gold standard in clinical and non-clinical practice. However, these techniques have a number of limitations. In particular, they are costly, sizeable, intrusive, and operator dependent. Recent research has demonstrated that near infrared spectroscopy could be used as a non-intrusive alternative for the measurement of skin water content. The present paper reports the development and in-vitro validation of a noninvasive, portable, skin hydration sensor. The results indicate that the developed sensor can deliver reliable measurements of skin water content.

An in vitro Raman study on compositional correlations of lipids and protein with animal tissue hydration

Raman spectroscopy is a powerful non-invasive tool for detection and classification of chemical composition of materials including biological tissues. In this work, we report an in vitro Raman study on animal skin samples with a focus on high-frequency vibrations such as symmetric CH₃ stretching mode at 2934 cm^-1, and the symmetric CH₂ vibration mode at 2854 cm^-1, OH stretching modes near 3412 cm^-1, and bounded OH mode near 3284 cm^-1. Raman data was acquired with a customized InGaAs based Raman spectrometer that consolidates the NIR (866 nm) light and the InGaAs detector and is particularly suitable for probing high-frequency vibrations. The Raman spectra of fat, tendon, and muscle tissues are also analyzed to determine the spectroscopic identities of CH and OH groups in skin. Our results suggest that the protein is beneficial for the maintenance of skin hydration, as it has higher water capacity and greater capability to retain water than lipids. This conclusion is consistent with the additional discovery that water exists in fat mainly as unbound type, while part of water exists as bound type in muscle.

Novel confocal Raman microscopy method to investigate hydration mechanisms in human skin

BACKGROUND

Skin hydration is essential for maintaining stratum corneum (SC) flexibility and facilitating maturation events. Moisturizers contain multiple ingredients to maintain and improve skin hydration although a complete understanding of hydration mechanisms is lacking. The ability to differentiate the source of the hydration (water from the environment or deeper skin regions) upon application of product will aid in designing more efficacious formulations.

MATERIALS AND METHODS

Novel confocal Raman microscopy (CRM) experiments allow us to investigate mechanisms and levels of hydration in the SC. Using deuterium oxide (D₂ O) as a probe permits the differentiation of endogenous water (H₂ O) from exogenous D₂ O. Following topical application of D₂ O, we first compare in vivo skin depth profiles with those obtained using ex vivo skin. Additional ex vivo experiments are conducted to quantify the kinetics of D₂ O diffusion in the epidermis by introducing D₂ O under the dermis.

RESULTS

Relative D₂ O depth profiles from in vivo and ex vivo measurements compare well considering procedural and instrumental differences. Additional in vivo experiments where D₂ O was applied following topical glycerin application increased the longevity of D₂ O in the SC. Reproducible rates of D₂ O diffusion as a function of depth have been established for experiments where D₂ O is introduced under ex vivo skin.

CONCLUSION

Unique information regarding hydration mechanisms are obtained from CRM experiments using D₂ O as a probe. The source and relative rates of hydration can be delineated using ex vivo skin with D₂ O underneath. One can envision comparing these depth-dependent rates in the presence and absence of topically applied hydrating agents to obtain mechanistic information.

Understanding the effects of topography on skin moisturization measurement via two-dimensional capacitance imaging

OBJECTIVE

Methods which assess skin moisturization based on changes in its electrical properties are widely used in both cosmetic and medical research industries. However, the devices themselves often give results which are significantly different to each other. Recently two-dimensional imaging moisturization systems have become commercially available, which have the capability to provide a more detailed assessment of what is contributing to measured skin moisturization. Presented here is a new in vitro method for preparing textured model test substrates for use with these devices, and results of their use to provide a clearer insight into the devices operation.

METHODS

A variety of different textured model test substrates were measured using a commercially available skin moisturization measurement device, the Epsilon. The response of the Epsilon was also tested against conventional skin moisturization devices.

RESULTS

Surface morphology of model test substrates was found to have a significant influence on the measurement of its electrical properties with both the conventional and two-dimensional skin moisturization measurement devices. Through modification of the areas of the image being assessed for the two-dimensional moisturization mapping device, the parts of the model test substrate in contact with the device were indentified and analysed separately to areas not in contact with the sensor. This provided a more robust assessment of the electrical properties of substrate itself, rather than being influenced by texture like the conventional skin moisturization measurement devices.

CONCLUSIONS

While the two-dimensional moisturization mapping systems can be used like a conventional electrical skin measurement device giving a simple overall reading of skin moisturization for the test area, their true value over existing electrical measures comes from its ability to isolate the skin itself from areas which are not in contact with the sensor.