A long term study of the difference in efficacy and effect rate of various concentrations of retinol (1500-6600 IU) in middle aged women.

Retinol is widely used for topical application for antiaging. However, the efficacy and effect rate of different concentrations of retinol have been rarely analyzed. Therefore, in this study, the efficacy and rate of effect of retinol concentrations from 1500 to 6600 IU, on various skin parameters, have been compared. Seventy-two Korean women aged 40-59 years participated in this study. Retinol was used by them for 24 weeks; the effects were measured at 0, 2, 4, 8, 12, and 24 weeks. The measurement parameters for aging were crow's feet, forehead wrinkles, nasolabial fold, dermal density, and elasticity and that for skin color were skin brightness, yellowness, redness, and standard deviation of skin brightness. The texture of the skin was measured by measuring the skin roughness and pores, and the skin barrier function was evaluated through hydration, sebum, and desquamation. Low concentration retinol (1500-2500 IU) had a significantly higher effect in skin color, brightness, and elasticity and faster improvement rate in skin brightness and elasticity compared to that for high concentration (3300-6600 IU). High concentration of retinol had a significantly higher effect in wrinkles, dermal density and pores and faster improvement rate for wrinkles, skin texture, pores, and desquamation compared to that for low concentration. This study evaluated the changes caused by different concentration of retinol over a long period of time. The results of this study have great implications as the optimal concentration of retinol can be prescribed for an accurate period for the desired results without side effects.

Dynamic visualization of ultraviolet dose on skin with sunscreen applied using minimum erythema dose.

BACKGROUND: Visualizing the ultraviolet (UV) dose on skin serve as an intuitive approach to ensure appropriate sunscreen usage and reduce the risk of erythema. UV dose is determined by a number of external factors, such as properties of sunscreens, weather, and type of outdoor activity. We propose a framework for visualizing UV doses that considers various external factors. MATERIALS AND METHODS: First, the skin of a three-dimensional human model was represented using triangular meshes, and various static postures and dynamic motions were simulated to express outdoor activities. Then, we evaluated the persistency and insufficiency properties of sunscreen, which are time dependent and directly affect the effectiveness of the sunscreen skin protection factor (SPF) during UV exposure. Finally, to calculate the UV dose in real time, we tracked the trajectory of the sun and motion of the skin while considering the time-dependent properties of sunscreen. RESULTS: An S/W system was implemented based on the proposed framework to visualize the distribution of UV doses through dynamic color changes in exposed skin areas. The color types include true colors, which represent the minimum erythema dose (MED), and pseudo colors representing states before 1 MED is reached. We devised various examples to discuss the usability of the proposed framework. CONCLUSION: The system conveniently displays the MED according to an individual's skin phototype. When the properties of a wide range of commercial sunscreens are added to the system database, it is expected that the rate of appropriate sunscreen usage by customers will increase.

Skin biophysical properties including impaired skin barrier function determine ultraviolet sensitivity.

BACKGROUND: The levels of burning susceptibility to ultraviolet (UV) radiations are affected by various factors, including Fitzpatrick skin types, skin color, sex, and ethnicity. However, studies on the relationship between skin biophysical properties and erythemal responses to UV radiations are rare. OBJECTIVE: This study aimed to investigate biophysical properties of the skin that determined individual skin sensitivity to UV radiation. METHODS: As an indicator of skin sensitivity to UV radiation, Korean women were subjected to minimal erythema dose (MED) testing. The skin biophysical properties, such as skin hydration, transepidermal water loss (TEWL), were measured. MED were also evaluated in further variations in the skin, including barrier disruption. RESULTS: A significant negative correlation was observed between TEWL and MED. With an increase in TEWL, that represents reduced skin barrier function, skin UV sensitivity also increased. Artificial alteration of skin conditions also changed erythemal response to UV radiation. When the skin barrier was disrupted, MED significantly decreased, indicating increased skin UV sensitivity. It is hypothesized that the altered penetration of UV radiation into the stratum corneum under the respective skin conditions caused different erythema reactions. CONCLUSION: For the first time in a clinical study, the skin biophysical properties, including skin barrier function, were found to have significant effects on skin sensitivity to UV radiation. This finding could help predict individual susceptibility to UV damage. Therefore, skincare products that improve skin conditions associated with UV sensitivity, as well as sunscreen are important for protection against the hazards of UV radiation.

Layering sunscreen with facial makeup enhances its sun protection factor under real-use conditions.

BACKGROUND: The proper application of sunscreen is important to ensure protection of the skin against ultraviolet (UV) damage. Sunscreens are used in various ways in real world situations, which alters their UV protection efficacy. In this study, we simulated typical consumer use of sunscreen, which is often sequentially covered with facial makeup, in a laboratory study. METHODS: We compared the sun protection factors (SPF) of sunscreen and makeup products after consecutive layering of the products. RESULTS: The SPF of each sunscreen and makeup product was dramatically lower than stated on the label upon application of a typical amount used by a consumer, which is lower than recommended. For high-SPF products, the drop in effective protection was proportionally greater than those for the low-SPF products upon application of lower doses. However, layering sunscreen and makeup products greatly increased the effective SPF compared with that achieved by single application of each product, even when the amount of each product used was below the recommended level. CONCLUSION: Layering sunscreen with makeup may compensate for insufficient sunscreen application in real-life conditions by providing an additional source of UV protection and improving the homogeneity of coverage. Our results suggest that recommending consecutive application of sunscreen and makeup products may be a practical and useful approach to improving UV protection that would not require additional steps in the facial care routines of many individuals.

Evaluation of anisotropic properties of striae distensae with regard to skin surface texture and viscoelasticity.

BACKGROUND: Striae distensae (SD) are skin lesions of parallel streaks, which mostly occur during rapid tissue expansion. Considering the etiological mechanism of SD, including dermal network ruptures and alignment to mechanical stretch, structural directionality or anisotropy could be expected. Non-invasive objective methods for measuring the anisotropy of SD have not been suggested yet. Therefore, we evaluated the anisotropic properties of SD with regard to skin surface texture and viscoelasticity, to verify them as new objective evaluation parameters of SD. METHODS: Thirty-two healthy subjects with SD on their body participated. Anisotropy of skin surface texture and biomechanical properties of SD-involved skin and adjacent normal skin was assessed and compared. RESULTS: Analysis of skin surface texture, based on the ×60 magnified images, revealed that SD have more disordered patterns compared to the regular honeycomb patterns seen in the normal surrounding skin. SD have bigger sizes of each blob than normal skin. The overall anisotropy of skin texture was significantly higher in SD. Skin biomechanical parameters, measured using Cutiscan® , indicated the less deformable, less recovered, and less viscoelastic properties of SD. When comparing viscoelastic properties over 360°, SD were more anisotropic than the adjacent normal skin as well. CONCLUSION: We observed that SD were significantly more anisotropic than adjacent normal skin with regard to skin surface texture and viscoelasticity. Therefore, anisotropy could be an objective evaluation parameter to represent the distinctive features of SD. It can be applied for evaluation of the SD severity and clinical efficacy of various treatments.