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Sleep Wrinkles: Facial Aging and Facial Distortion During Sleep
Abstract
Wrinkles are just one indicator of facial aging, but an indicator that is of prime importance in our world of facial aesthetics. Wrinkles occur where fault lines develop in aging skin. Those fault lines may be due to skin distortion resulting from facial expression or may be due to skin distortion from mechanical compression during sleep. Expression wrinkles and sleep wrinkles differ in etiology, location, and anatomical pattern. Compression, shear, and stress forces act on the face in lateral or prone sleep positions. We review the literature relating to the development of wrinkles and the biomechanical changes that occur in response to intrinsic and extrinsic influences. We explore the possibility that compression during sleep not only results in wrinkles but may also contribute to facial skin expansion.
... A review article about sleep wrinkles generated an AAS of 729 but had only 3 citations. 31 The other 4 studies with the highest AAS scores were related to hair transplant, breast reconstruction, e-cigarettes, and the plastic surgery hashtag ("#plasticsurgery"). 22,[31][32][33][34] It can be argued that these articles are neither novel nor present a major scientific impact but are, however, of public interest. The online presence of certain journals and the selection of specific articles to be promoted on the journal social media platforms may impact the AAS but has an uncertain effect on the citation count. ...
... A review article about sleep wrinkles generated an AAS of 729 but had only 3 citations. 31 The other 4 studies with the highest AAS scores were related to hair transplant, breast reconstruction, e-cigarettes, and the plastic surgery hashtag ("#plasticsurgery"). 22,[31][32][33][34] It can be argued that these articles are neither novel nor present a major scientific impact but are, however, of public interest. The online presence of certain journals and the selection of specific articles to be promoted on the journal social media platforms may impact the AAS but has an uncertain effect on the citation count. ...
... 28 For example, the review article on sleep wrinkles was titled by several news outlets as "The Ultimate Solution For The New Wrinkle Has Arrived." 31,35 However, the article did not offer any treatment or ultimate solution for wrinkles but rather recommended sleeping on the back for decreasing sleep wrinkles, acknowledging that "we unconsciously change position throughout the night" and that the "the consequence of repetitive stretching of facial tissue over time . . . warrants further study." ...
Background
Altmetrics (alternative metrics) has become one of the most commonly used metrics to track the impact of research articles across electronic and social media platforms.
Objective
The goal of this study is to identify whether the Altmetric Attention Score (AAS) is a good proxy for citation counts and whether it can be used as an accurate measure to complement the current gold standard.
Methods
We conducted a citation analysis of all articles published in six plastic surgery journals during the 2016 calendar year. Citation counts and AAS were abstracted and analyzed.
Results
We identified a total of 1,420 articles. The mean AAS was 11 while the median AAS was 1. The journal with the highest mean AAS was Aesthetic Surgery Journal (31), followed by Plastic and Reconstructive Surgery (19). A weak positive correlation was identified (r=0.33, p<0.0001) between AAS and citations. Articles in the top 1% in terms of citation counts showed strong positive correlation between AAS and citation counts (r=0.64, p=0.01). On the contrary, articles in the top 1% of AAS had no significant correlation with citation counts (r=-0.31, p=0.29).
Conclusion
Overall correlation between citations and AAS was weak, and therefor AAS may not be an accurate early predictor of future citations. The two metrics seem to measure different aspects of the impact of scholarly work and should be used in tandem for determining the reach of a scientific article.
... Exhibit 1: Pierard Classification of Wrinkles [26] Atrophic wrinkles develop in exposed and nonexposed skin, disappear with skin traction, change in orientation with body posture, and are due to atrophy of the extracellular matrix. Elastotic wrinkles develop in sun exposed skin, exhibit solar elastosis, become progressively permanent, and do not disappear with perpendicular traction. ...
... Expression wrinkles and sleep wrinkles differ in etiology, location, and anatomical pattern. Compression, shear, and stress forces act on the face in lateral or prone sleep positions ( Figure 6) [26]. Diet and Nutrition: Rhytides, sagging of skin, and loss of elasticity are all related to changes in the collagen and elastic fibers of the skin, which are themselves impacted by diet. ...
... External forces (including compression, tension, and shear) act on facial tissue in lateral or prone sleep positions[26]. During side or stomach sleeping, facial tissue is subject to shear, compression, and tensile mechanical forces. ...
As the most voluminous organ of the body that is exposed to the outer environment, the skin suffers from both intrinsic and extrinsic aging factors. Skin aging is characterized by features such as wrinkling, loss of elasticity, laxity, and rough-textured appearance. This aging process is accompanied with phenotypic changes in cutaneous cells as well as structural and functional changes in extracellular matrix components such as collagens and elastin. With intrinsic aging, structural changes occur in the skin as a natural consequence of the biological changes over time and produce a certain number of histological, physiological, and biochemical modifications. Intrinsic aging is determined genetically (influence of gender and ethnic group), variable in function of skin site, and also influenced by hormonal changes. Visually it is characterized by fine wrinkles. By comparison, “photoaging” is the term used to describe the changes occurring in the skin, resulting from repetitive exposure to sunlight. The histological, physiological, and biochemical changes in the different layers of the skin are much more drastic. From a mechanical point of view, human skin appears as a layered composite containing the stiff thin cover layer presented by the stratum corneum, below which are the more compliant layers of viable epidermis and dermis and further below the much more compliant adjacent layer of subcutaneous white adipose tissue.
... Usually skin wrinkles emerge and increase along with the aging processes, and extensive skin wrinkles exist in elder mammals, especially for facial wrinkles. According to histological differences and possible causes, skin wrinkles were typically classified into five categories: atrophic wrinkles, elastotic wrinkles, expressional wrinkles, gravitational wrinkles and sleep wrinkles, respectively [1][2][3][4]. It has been reported that many intrinsic and extrinsic factors contributed to skin wrinkle development and formation [4,5], which included slower epidermal turnover, increased skin fragility, decreased nutrients transfer between skin layers, loss of sebaceous glands and reduced oil production in skin, loss of fat support and less padding of fat tissue under skin, ultraviolet oxidative damage, harsh weather and pollution, and repeated skin movement. ...
... According to histological differences and possible causes, skin wrinkles were typically classified into five categories: atrophic wrinkles, elastotic wrinkles, expressional wrinkles, gravitational wrinkles and sleep wrinkles, respectively [1][2][3][4]. It has been reported that many intrinsic and extrinsic factors contributed to skin wrinkle development and formation [4,5], which included slower epidermal turnover, increased skin fragility, decreased nutrients transfer between skin layers, loss of sebaceous glands and reduced oil production in skin, loss of fat support and less padding of fat tissue under skin, ultraviolet oxidative damage, harsh weather and pollution, and repeated skin movement. ...
Wrinkles are uneven concave-convex folds, ridges or creases in skin. Facial wrinkles appear in head, typically increasing along with aging. However in several Chinese indigenous pigs, such as Erhualian pigs, rich facial wrinkles have been generated during the growth stages as one of their breed characteristics. To investigate the genetic basis underlying the development of swine facial wrinkles, we estimated the folding extent of facial wrinkles in a herd of Erhualian pigs (n=332), and then conducted genome-wide association studies and multi-trait meta-analysis for facial wrinkles using 60K porcine chips. We found that facial wrinkles had high heritability estimates of ~0.7 in Erhualian pigs. Notably, only one genome-wide significant QTL was detected at 34.8 Mb on porcine chromosome 7. The most significant SNP rs80983858 located at the 3255-bp downstream of candidate gene GRM4, and the G allele was of benefit to increase facial wrinkles. Evolutionary and selection analyses suggested that the haplotypes containing G allele were under artificial selection, which was consistent with local animal sacrificial custom praying for longevity. Our findings made important clues for further deciphering the molecular mechanism of swine facial wrinkles formation, and shed light on the research of skin wrinkle development in human or other mammals.
... The severity of wrinkles varies by skin type and increases with age. [14][15][16] During the aging process, various cells secrete endopeptidases that can degrade extracellular matrix proteins called MMPs. MMP-1 is the major protease in human skin which degrades collagen types I and III, regulated by TIMPs. ...
Introduction: The elderly population wants to improve skin function and maintain a youthful appearance without wrinkles. Laser is one of the highly developed and widely used therapeutic modalities of skin aging by stimulating dermal collagen formation. Picosecond laser therapy is performed on skin with wrinkles to determine the mechanism of wrinkle improvement with a picosecond laser through an increasing in tissue inhibitor of metalloproteinases 1 (TIMP-1), and a decrease in matrix metalloproteinase-1 (MMP-1), which was confirmed by collagen density. Methods: The study was started from March 2021 to July 2021 at URJ Dr. Soetomo Hospital Surabaya and Surabaya Skin Centre. Twenty patients meeting the inclusion criteria of being 36-55 years of age and having a wrinkle in the forearm were enrolled by random sampling. Each sample data was recorded, the average TIMP-1, MMP-1, collagen density, and clinical wrinkles were calculated, and the laser was performed by using a picosecond 755 nm laser. Results: All patients showed a moderate pre-test wrinkle scale. The figure for TIMP-1 and MMP-1 after therapy was higher. The MMP-1/TIMP-1 ratio in wrinkles treated by using a picosecond laser was lower but insignificant than before. The picture of collagen density indicates that collagen density after laser therapy was higher than before. Conclusion: The result of clinical examination, histopathology, and immunohistochemistry in this research explained that a picosecond 755 nm laser with DLA is an effective therapy for wrinkles in Indonesian patients without any adverse effects.
... The differences in wrinkles between the right and left sides of the face observed in the present study could be due to the different sleep postures of the subjects. Facial wrinkles are formed as a result of the pressure exerted on the face during sleep, thereby promoting facial skin expansion [14]. ...
Introduction: Wrinkles commonly manifest in various areas of the face as individuals age. This study aimed to assess the association between facial wrinkles and different facial forms.
Materials and methods: An observational, prospective study was conducted on the facial photographs of 400 subjects aged 40-60 years, which were divided into four groups of 100 subjects each: Group 1, square facial form; Group 2, ovoid facial form; Group 3, square tapered facial form; and Group 4, tapered facial form. All groups had almost equal distributions of males and females. Six types of facial wrinkles were studied, namely, forehead, glabellar, canthal, nasolabial, wrinkles at the corner of the mouth, and perioral wrinkles. Analysis of variance (ANOVA) was used for intergroup comparison, and an independent Student's t-test was used to assess gender differences in facial wrinkles.
Results: Significant gender differences were observed for forehead wrinkles in Groups 1 and 3, canthal wrinkles in Groups 1 and 2, and right perioral wrinkles in Group 1 (p<0.05). There were non-significant gender differences between right and left-side facial wrinkles (p>0.05). Significant differences between the groups were observed for all facial wrinkles between the right and left sides of the face (p<0.05). There was a significant difference between the groups for the presence of glabellar, corner of the mouth, and perioral wrinkles, with the presence of higher wrinkles in ovoid and tapered facial forms compared to square and square tapered facial forms (p<0.05).
Conclusions: Females had more facial wrinkles than males, predominantly in the forehead region. The least prominent wrinkles were observed in the perioral region of the face. Glabellar, corner of the mouth, and perioral wrinkles were predominantly observed in ovoid and tapered facial forms.
... Like facial sleep wrinkles as described by Anson et al, 8 Figure 7A shows an example of sleep cheek wrinkles in a 63-year-old East-Asian man. There were two wrinkles over the left lower cheek extending up to the mandibular border (the patient has slept on his left side for decades). ...
Background:
Wrinkles are one of the key signs of an aging face. Cheek wrinkles have a prominent negative impact on facial aesthetic. Recognizing the pathology and types of different cheek wrinkles, and the possible minimal invasive interventions to treat them, are crucial for optimal aesthetic outcome.
Objective:
The classification of cheek wrinkles based on etiology, past literature, and wrinkle pattern, and the outlining of possible treatment options.
Result:
Five different types of cheek wrinkles are described: Type 1-Atrophic cheek wrinkles, Type 2-dynamic expressional cheek wrinkles, Type 3-static expressional cheek wrinkles, Type 4-laxity cheek wrinkles, and Type 5-sleep cheek wrinkles. Treatment options and techniques for different types of cheek wrinkles are recommended accordingly.
... Sleep lines have long been attributed to the various mechanical forces exhibited on the superficial musculoaponeurotic system. 77,78 These effects lead to various facial skin changes and wrinkles that become permanent with repeated pressure. 79 We did not identify significant differences in skin roughness or density between the left and right sides of the face. ...
Objectives:
The skin aging exposome encompasses internal and external factors that contribute to clinical signs of facial aging. Aging skin can be characterized by distinctive features such as wrinkles, lentigines, elastosis, and roughness. Optical coherence tomography (OCT) is capable of noninvasively measuring skin characteristics. This study aimed to assess bilateral features using OCT to explore temporal skin changes among decades and potential changes in facial skin aging based on laterality.
Methods:
A total of 97 subjects between 20 and 89 years old with Fitzpatrick skin types I to IV were enrolled. VivoSight, a Multi-Beam OCT system intended to gather topographical and histological images of skin, was used to scan the area inferolateral to the lateral canthus, bilaterally. Investigators compared characteristics of skin roughness, attenuation coefficient and blood flow across age groups and based on laterality to determine any differences.
Results:
Only data from successful OCT scans were used. Seventy subjects, 10 from each specified decade, had successful bilateral scans and were thus included in the analysis. Chronological aging was characterized by significantly decreased dermal attenuation coefficient with increased age. Skin roughness measurements showed trends of increased roughness with age; however, no statistically significant changes were seen between groups. Qualitative differences amongst scans taken on right and left sides of the face showed no significance regarding roughness, density or blood flow at depths ranging from 0.05 to 0.5 mm.
Conclusions:
OCT is an effective method for evaluating changes in aging skin. Our results illustrate a decline in skin density with chronological age. Additionally, it was illustrated that structural change in the epidermis and dermis does occur, however on a microscopic scale, there are no significant differences based on laterality. OCT holds promise as a noninvasive technique for characterization of aging skin. Its utility and application in the clinical management and treatment of aged skin requires further research; however, the technology has potential to personalize therapies based on objective findings.
... 14 The Altmetric scores for papers from this section, which measure the media exposure of scholarly publications, have been high, validating that there is both public interest in these articles and a desire to improve and refine clinical techniques and outcomes. [15][16][17][18][19][20] Among the most read are the articles by Ozturk et al 8 and DeLorenzi 9,10 on complications of injectable fillers, and the articles by Goodman et al 12 and Beleznay et al 11 on HA embolism and blindness. Finally, I draw your attention to a landmark paper by Goodman et al exploding the myth of aspiration before injection. ...
... • Gravitational wrinkles due to skin sagging in response to gravitational forces and inelasticity. Exhibit 1: Pierard classification of wrinkles [26]. ...
... Expression wrinkles and sleep wrinkles differ in etiology, location, and anatomical pattern. Compression, shear, and stress forces act on the face in lateral or prone sleep positions ( Figure 6) [27]. ...
... Expression wrinkles and sleep wrinkles differ in etiology, location, and anatomical pattern. Compression, shear, and stress forces act on the face in lateral or prone sleep positions ( Figure 6) [26]. ...
As the most voluminous organ of the body that is exposed to the outer environment, the skin suffers from both intrinsic and extrinsic aging factors. Skin aging is characterized by features such as wrinkling, loss of elasticity, laxity, and rough-textured appearance. This aging process is accompanied with phenotypic changes in cutaneous cells as well as structural and functional changes in extracellular matrix components such as collagens and elastin. With intrinsic aging, structural changes occur in the skin as a natural consequence of the biological changes over time and produce a certain number of histological, physiological, and biochemical modifications. Intrinsic aging is determined genetically (influence of gender and ethnic group), variable in function of skin site, and also influenced by hormonal changes. Visually it is characterized by fine wrinkles. By comparison, “photoaging” is the term used to describe the changes occurring in the skin, resulting from repetitive exposure to sunlight. The histological, physiological, and biochemical changes in the different layers of the skin are much more drastic. From a mechanical point of view, human skin appears as a layered composite containing the stiff thin cover layer presented by the stratum corneum, below which are the more compliant layers of viable epidermis and dermis and further below the much more compliant adjacent layer of subcutaneous white adipose tissue. Upon exposure to a strain, such a multi-layer system demonstrates structural instabilities in its stiffer layers, which in its simplest form is the wrinkling. These instabilities appear hierarchically when the mechanical strain in the skin exceeds some critical values. Their appearance is mainly dependent on the mismatch in mechanical properties between adjacent skin layers or between the skin and subcutaneous white adipose tissue, on the adhesive strength and thickness ratios between the layers, on their bending and tensile stiffness as well as on the value of the stress existing in single layers. Gradual reduction of elastic fibers in aging significantly reduces the skin’s ability to bend, prompting an up to 4-fold reduction of its stability against wrinkling, thereby explaining the role of these fibers in skin aging. Anti-aging medicine is practiced by physicians, scientists, and researchers dedicated to the belief that the process of physical aging in humans can be slowed, stopped, or even reversed through existing medical and scientific interventions. This specialty of medicine is based on the very early detection and prevention of age-related diseases. Physicians practicing anti-aging medicine seek to enhance the quality of life as well as its length, limiting the period of illness and disability toward the end of one’s life. Anti-aging medicine encompasses lifestyle changes (diet and exercise); hormone replacement therapies, as needed, determined by a physician through blood testing (DHEA, melatonin, thyroid, human growth hormone, estrogen, testosterone); antioxidants and vitamin supplements; and testing protocols that can measure not only hormone levels and blood chemistry but every metabolic factor right down to the cellular level.
... Replacement of dWAT volume with fibrosis leads to production of mechanically heterogeneous skin structures and to the loss of the effective skin volume. [8]. During side or stomach sleeping, facial tissue is subject to shear, compression, and tensile mechanical forces. ...
Skin aging is a complex biological process influenced by a combination of endogenous or intrinsic and exogenous or extrinsic factors. Because of the fact that skin health and beauty is considered one of the principal factors representing overall “well-being” and the perception of “health” in humans, several anti-aging strategies have been developed during the last years. In contrast to thin and atrophic, finely wrinkled and dry intrinsically aged skin, premature photoaged skin typically shows a thickened epidermis, mottled discoloration, deep wrinkles, laxity, dullness and roughness. Gradual loss of skin elasticity leads to the phenomenon of sagging. Slowing of the epidermal turnover rate and cell cycle lengthening coincides with a slower wound healing and less effective desquamation in older adults. This fact is important when esthetic procedures are scheduled. On the other side, many of these features are targets to product application or procedures to accelerate the cell cycle, in the belief that a faster turnover rate will yield improvement in skin appearance and will speed wound healing. A marked loss of fibrillin-positive structures as well as a reduced content of collagen type VII (Col-7, may contribute to wrinkles by weakening the bond between dermis and epidermis of extrinsically age skin. Sun-exposed aged skin is characterized by the solar elastosis. The sparse distribution and decrease in collagen content in photoaged skin can be due to increased collagen degradation by various matrix metalloproteinases, serine, and other proteases irrespective of the same collagen production. The overall collagen content per unit area of the skin surface is known to decline approximately 1%/year. Glycosaminoglycans (GAGs are among the primary dermal skin matrix constituents assisting in binding water. In photo-aged skin, GAGs may be associated with abnormal elastotic material and thus be unable to function effectively. The total hyaluronic acid (HA level in the dermis of skin that age intrinsically remains stable; however, epidermal HA diminishes markedly. Decreased estrogen levels may play a role in skin aging in women and compounds stimulating estrogen receptors could potentially counteract some of the visible signs of aging. As people live longer, women spend a larger portion of their lives in a post-menopausal state, with a deficiency of estrogen as compared to their younger selves. Changes in diet and increasing exercise, together with a regimen of antioxidants, nutritional supplements, and growth factors, can alter how the genes express themselves. Both factors can greatly enhance the healing capability of the skin and can improve the results of cosmetic surgeries.
... (v) Ercan et al. [3] proposed that there is a correlation between the level of facial asymmetry and facial side. Anson et al. [31] explored that facial wrinkles are developed by the compression during sleep which also contribute to facial skin expansion. The experimental results presented in our study support these notions, by showing that bilateral facial asymmetry based asymmetric right face images can be used for age estimation of a given face image with reduced MAE compared to its counterparts i.e., the original and left asymmetric face images. ...
Aging affects left and right half face differently owing to numerous factors such as sleeping habits, exposure to sun light, and weaker face muscles of one side of face. In computer vision, age of a given face image is estimated using features that are correlated with age, such as moles, scars, and wrinkles. In this study we report the asymmetric aging of the left and right sides of face images and its impact on accurate age estimation. Left symmetric faces were perceived as younger while right symmetric faces were perceived as older when presented to the state-of-the-art age estimator. These findings show that facial aging is an asymmetric process which plays role in accurate facial age estimation. Experimental results on two large datasets verify the significance of using asymmetric right face image to estimate the age of a query face image more accurately compared to the corresponding original or left asymmetric face image.
Purpose: This study aimed to confirm the skin improvement effects of cosmetics containing low-molecular-weight peptide complexes using in vitro and human application tests.Methods: An in vitro test was conducted to confirm the cytotoxicity, antioxidant, and anti-photoaging effects of cosmetics comprising low-molecular-weight peptide complexes. The protective effect on HacaT cells subjected to oxidative stress and collagen production in CCD-986sk cells irradiated with UV-B (Ultraviolet B) were confirmed. Moreover, to validate skin improvement effects, a human application test was performed on 20 adults aged 30–59 years. The wrinkles depth and the indentation index around the forehead, eyes, cheeks, and mouth were evaluated using ANTERA 3D CS.Results: The test material demonstrated excellent cell viability, confirming its safety on the skin. At a concentration of 0.1%, it exhibited a removal rate of reactive oxygen species (ROS) by 63.39% ( p <0.001) and an increase in collagen content of 102.14% ( p <0.01). Furthermore, in the human application test over 4 weeks, skin folds exhibited a decrease in average depth by 20.53% ( p <0.001), and the indentation index decreased by 17.02% ( p <0.001).Conclusion: Cosmetics containing low-molecular-weight peptide complexes possess excellent antioxidant, anti-photoaging, and collagen synthesis promotion properties. Their efficacy in reducing skin wrinkles and increasing skin elasticity was also confirmed. Low-molecular-weight peptide complexes could be an excellent active ingredient in cosmeceuticals.
The skin, due to its protective role, suffers from exogenous factors (ultraviolet radiation, pollution and trauma) and endogenous factors (endocrine-metabolic diseases, alcohol and tobacco use), a sequence of functional alterations and/or structural problems that could harm its integrity, leading to dyschromia, dehydration, loss of elasticity and microvascular alterations. Wrinkles are an indicator of facial aging, with fault lines occurring in the skin, due to skin distortions resulting from facial expression or mechanical movements and compressions during sleep. Expression and sleep wrinkles differ in etiology, location and anatomical pattern. The skin during sleep undergoes compression, shear and tension forces that act on the face when we are in lateral or prone sleeping positions. Hyaluronic acid, since the 1990s, has been employed as a favorable temporary filler option for facial augmentation and for the regulation of various biological processes, such as skin repair, wound healing, tissue regeneration, reaching the prominent place regarding the treatment of wrinkles. This work aims to report a case of treatment of sleep wrinkles, in a female patient, only treated with fillers based on hyaluronic acid, with the “Fern Pattern Technique” technique with evolution of 2 years and with a single application.
Nanotechnology is an innovative area of science that deals with things smaller than 100 nanometers. The influence of nanotechnology in the cosmetic industry is overwhelming since it can enhance the properties attained by the particles at the nano level which includes color, solubility, etc, and also promotes the bioavailability of API. A plethora of nanomaterials can be employed in cosmetics including organic and inorganic nanoparticles. Unlike orthodox carriers, they facilitate easy penetration of the product into the skin and thereby increasing the stability and allowing a controlled drug release so that they can permeate deeper into the skin and start revitalizing it. Nanomaterials rejuvenate the skin by forming an occlusive barrier to inhibit the loss of water from the skin’s surface and thereby moisturize the skin. Nano-cosmeceuticals are used to provide better protection against UV radiation, facilitate deeper skin penetration, and give long-lasting effects. Although they still have some safety concerns, hence detailed characterization or risk assessments are required to fulfill the standard safety requirements. In this review, an attempt is made to make a brief overview of various nanocosmeceutical skincare and anti-aging products.
Purpose:
To investigate the relationship between sleep position preference and eyebrow and eyelid position and degree of upper eyelid dermatochalasis.
Methods:
A prospective study evaluating the impact of sleep position on facial asymmetry was conducted at an academic ophthalmology department. Eligibility criteria included the absence of periocular-altering trauma or surgery, contact lens use, or other periorbital disease processes. Patients reported their sleep position preference on a questionnaire. Standardized digital photographs of patients were obtained, and Image J software was used for measurements and converted into millimeters based on a standard corneal limbus-to-limbus ratio. Upper and lower eyelid position, upper eyelid dermatochalasis, and eyebrow position were assessed by the following image-derived measurements: marginal reflex distance 1 (iMRD1), marginal reflex distance 2 (iMRD2), tarsal platform show (iTPS), and central brow position (iBP). These results were compared with the patient reported sleep position preference to determine correlation.
Results:
Seventy-one patients were enrolled and reported the following sleep position preferences: 28 (right), 24 (left), 13 (both), and 6 (supine). Patients with a right- or left-sided preference demonstrated lower iMRD1 measurements for the preferred sleep side (p < 0.0004) with no other significant difference in periorbital measurements. A larger degree of upper eyelid height (iMRD1) asymmetry was observed among patients with a sleep side preference.
Conclusion:
Patients with a predominant sleep side preference demonstrate a significant increase in ipsilateral upper eyelid asymmetry and an inferior upper eyelid position on the sleep side. There were no differences noted in lower eyelid position, central eyebrow position, or amount of upper eyelid dermatochalasis.
Background
A new topical formulation (TF) based on 3 main lifting components has been developed to reduce superficial facial wrinkles.
Objectives
Determine the effectiveness of this new TF in reducing superficial face wrinkles and restructuring the dermal matrix.
Methods
Women, aged 30‐65 y.o. with moderate to severe crow's feet wrinkles were included. Exclusion criteria: men; younger than 30 or older than 65 years old; smokers. Patients received 15 IU of botulinum toxin on crow's feet and 2 creams. Fifty patients (Group 1) applied the TP (Product A) and 50 (Group 2) a placebo (Product B). Assessments were made by digital macro‐photography's, Antera 3D, and a patient satisfaction questionnaire.
Results
From April to June 2019, 100 women were enrolled in the study and were divided into two homogeneous groups. No major or minor side effects were reported. In group 1, wrinkles, texture, static and dynamic crow's feet wrinkles improved significantly at 3 and 6 months. Patients were very satisfied at 3 months and satisfied at 6 months. In group 2, wrinkles and texture improved significantly at 3 months but did not improve at 6 months. Static and dynamic crow's feet wrinkles improved significantly at 1 and 3 months but did not improve significantly at 6 months.
Conclusions
Our prospective and randomized study has shown that the new TF is safe and effective in reducing superficial face wrinkles and producing dermal regeneration. It, therefore, prolongs the duration of the botulinum toxin. Further controlled study would be necessary to compare the new TF to neurotoxin treatment, or its action alone.
The ongoing positive aging trend has resulted in many research studies being conducted to determine the characteristics of aging and what steps we can take to prevent the extrinsic signs of aging. Much of this attention has been focused on the prevention and treatment of facial wrinkles. To treat or prevent facial wrinkles correctly, their causative action first needs to be determined. published very compelling evidence that the development of wrinkles is complex and is caused by more factors than just the combination of poor lifestyle choices.
During growth and development, the skin expands to cover the growing skeleton and soft tissues by constantly responding to the intrinsic forces of underlying skeletal growth as well as to the extrinsic mechanical forces from body movements and external supports. Mechanical forces can be perceived by two types of skin receptors: (1) cellular mechanoreceptors/mechanosensors, such as the cytoskeleton, cell adhesion molecules and mechanosensitive (MS) ion channels, and (2) sensory nerve fibres that produce the somatic sensation of mechanical force. Skin disorders in which there is an abnormality of collagen [e.g. Ehlers-Danlos syndrome (EDS)] or elastic (e.g. cutis laxa) fibres or a malfunction of cutaneous nerve fibres (e.g. neurofibroma, leprosy and diabetes mellitus) are also characterized to some extent by deficiencies in mechanobiological processes. Recent studies have shown that mechanotransduction is crucial for skin development, especially hemidesmosome maturation, which implies that the pathogenesis of skin disorders such as bullous pemphigoid is related to skin mechanobiology. Similarly, autoimmune diseases, including scleroderma and mixed connective tissue disease, and pathological scarring in the form of keloids and hypertrophic scars would seem to be clearly associated with the mechanobiological dysfunction of the skin. Finally, skin ageing can also be considered as a degenerative process associated with mechanobiological dysfunction. Clinically, a therapeutic strategy involving mechanoreceptors or MS nociceptor inhibition or acceleration together with a reduction or augmentation in the relevant mechanical forces is likely to be successful. The development of novel approaches such as these will allow the treatment of a broad range of cutaneous diseases.
The study addressed the influence of sleep as an important but overlooked contributory factor to the formation and progression of facial wrinkles and an alternative pillow was designed to reduce them.
Fifteen healthy young participants of both sexes (aged 26-42 years) volunteered for this study. We used a transparent PVC pillow filled with air to demonstrate mechanical forces and deformations of the face as a consequence of sleeping on a pillow. We used a Podometer (PDMTR) (integrated fluorescent luminaire lamp) as a diagnostic device to visualize and to document the imprint of facial deformities on a glass, as seen during sleeping.
We observed various facial deformities and wrinkles during sleep ('crow's feet' fine lines, lines around the mouth, flattening of the forehead, blunting of the nasofrontal angle, melolabial and nasolabial folds) and design an alternative pillow to reduce them by redistributing the pressure from the wrinkling parts of the face.
Knowledge of the mechanical properties of the human skin is very important for cosmetic and clinical research. Objective and quantitative measurements are essential to compare studies performed by different experimenters in different centres. The aim of this paper is to present a method to measure the viscoelastic properties of human skin in vivo using dynamic indentation.
A complete device to assess the stiffness and damping of skin has been developed. The frequency and strain amplitude range from 10 to 60 Hz and from 1 to 10 mum. Tests on pure elastic inert materials have been performed to validate the device. An in vivo study including dynamic indentation, suction test, hydration measurement and topographic analysis has been performed on 46 subjects aged from 18 to 70 years, divided into three groups.
Results on inert materials show the validity of the device developed. The mechanical behaviour of the skin can be described by a Kelvin-Voight model under dynamic indentation. A comparison with a suction test, hydration and topographic measurements shows that the stiffness and the damping measured by dynamic indentation correspond mainly to the natural tense state of the skin on the body due to the dermis. A weak correlation has been found between dynamic indentation and suction parameters. The complex modulus measured by dynamic indentation at 10 Hz frequency stress ranges from 7.2 +/- 2.1 kPa for the oldest group to 10.7 +/- 2.6 kPa for the youngest group.
The device presented gives convincing results. The measurement of stiffness and damping complements the viscoelastic phenomenological parameters of the suction test.
In an attempt to characterize the development of sleep positions and position shifts in the human, 10 subjects (5 males and 5 females) in each of the following five age groups were studied: 3-5, 8-12, 18-24, 35-45 and 65-80 years old. Subjects slept for four consecutive nights (except the 3-5 year olds who slept two nights) in the laboratory where standard polysomnography was recorded. On nights 3 and 4, sleep positions were recorded with a Super 8 Camera taking one frame every 8 seconds and were scored using four dimensions (head, trunk, legs and arms) each consisting of four categories. The results revealed a significant ontogenetic decrease in the number of position shifts with averages of 4.4, 4.7, 3.6, 2.7 and 2.1 changes per hour, respectively. There was a corresponding progressive increase in the duration of positions and in the number of periods of more than 30 minutes of postural immobility. Whereas in children, prone, supine and lateral positions were assumed to occupy an equal proportion of sleep time, trend analyses revealed a significant progressive ontogenetic disappearance of prone positions and a progressive preference, very marked in the elderly, for right-side positions.
This study documents the anatomy of the deep attachments of the superficial fasciae within the temporal and periorbital regions. A highly organized and consistent three-dimensional connective tissue framework supports the overlying skin and soft tissues in these areas. The regional nerves and vessels display constant and predictable relationships with both the fascial planes and their ligamentous attachments. Knowledge of these relationships allows the surgeon to use the tissue planes and soft-tissue ligaments as intraoperative landmarks for the vital neurovascular structures. This results in improved efficiency and safety for aesthetic procedures in these regions.
An increasing number of injectable filler materials for facial wrinkles and folds points to the need for objective measurements of their effectiveness. Patient satisfaction is the goal, but proof of the value of a particular product requires objective measurement. A wrinkle assessment scale was developed as a simple tool for use by plastic surgeons, dermatologists, and aesthetic surgeons who want to assess the changes resulting from injecting filler materials in their patients. By correlating the grade of the wrinkle in the reference photographs with the wrinkle in a patient's face, a classification of 0 to 5 is assigned. Reliability of the scale was assessed by "live" judgment of 76 wrinkles by nine observers. The same rating was given to 92.7 percent of all wrinkles. In a second trial, photographs from 130 wrinkles were presented to eight observers who rated 89.4 percent of all wrinkles equally. A significant correlation of 87 percent was found between subjective ratings and objective wrinkle depth measured by profilometry on 40 silicone impressions. Manufacturers, monitors of clinical trials, health authorities, and most important, patients will benefit from objective data on current and new injectable materials.
Wrinkles are modifications of the skin associated with cutaneous ageing and develop preferentially on sun-exposed skin. The aim of the study was to analyse the clinicopathological features of wrinkles, among the different types of skin relief modifications. Despite its importance in dermato-cosmetology and skin ageing, few studies have been specifically devoted to wrinkles. In the present study, we analyzed the histological features of the pre-auricular wrinkle compared to retro-auricular skin, obtained from sixteen patients undergoing facial surgery; skin samples were immediately processed for routine histology and histochemical staining. Four types of skin depressions could be defined according to their depth: folds, permanent wrinkles, reducible wrinkles and skin micro-relief. Two different types of pre-auricular wrinkles were observed: (i) permanent wrinkles which were conserved after sampling and, (ii) reducible wrinkles which required in vivo staining to be visible at histology. Histological analysis of the epidermis and dermis of the skin forming the pre-auricular wrinkle revealed a normal skin morphology, identical to that of the skin immediately adjacent to the wrinkle. This was particularly striking for the reducible wrinkles which could not be individualized in the absence of in vivo staining. Both types of wrinkles comprised skin modifications observed in sun-exposed skin, however, in the upper dermis, permanent wrinkles showed a more pronounced accumulation of basophilic fibers, i.e. actinic elastosis, than reducible wrinkles did. These data suggest that the development of wrinkles could be secondary to actinic elastosis and to the disappearance of microfibrils and collagen fibers at the dermal-epidermal junction.
The anatomy of the midcheek has not been satisfactorily described to adequately explain midcheek aging and malar mounds, nor has it suggested a logical approach to their correction or provided sufficient detail for safe surgery in this area. This cadaver study, which was complemented by many operative dissections, located a missing link: a glide plane space overlying the body of the zygoma. The space functions to allow mobility of the orbicularis oculi, where it overlies the zygoma and the origins of the elevator muscles to the upper lip. The space is a cleft between the sub-orbicularis oculi fat and the preperiosteal fat and is lined by a fine membrane. The anatomic boundaries are clearly defined by retaining ligaments, which correlate with the triangularity of the space. Several anatomic features provide the functional characteristics of the prezygomatic space, including the (1) absence of direct attachments between the orbicularis in the roof to the floor, (2) more rigid inferior boundary formed by the zygomatic ligaments, and (3) more mobile upper ligamentous boundary formed by the orbicularis retaining ligament (separating from the preseptal space of the lower lid). These components determine the characteristic aging changes that occur in this region and explain much about malar mounds. An appreciation of this anatomy has several surgical implications. The prezygomatic space is a junction area that can be approached from the temple, lower lid, and cheek. The zygomatic branches of the facial nerve to the orbicularis do not cross the space; rather, they course in the walls and in the sub-orbicularis fat within the roof of the space.
Description of the surgical anatomy of the superficial fascia of the face must include its deep attachments. These attachments have been mapped out for the forehead, temple, and cheek as retaining ligaments. The deep attachments of the orbicularis oculi of the lower lid and lateral canthus have long been recognized in canthopexy surgery but have yet to be properly defined. Six fresh cadavers were dissected with histologic support, and the results were correlated with surgical observations. The fascia of the deep aspect of the orbicularis is attached to the periosteum of the orbital rim by an orbicularis retaining ligament. This attachment is weakest centrally and tightest over the inferolateral orbital rim. The retaining ligament fuses with an expanded fibrous attachment beyond the lateral canthus, the lateral orbital thickening, which extends over the lateral orbital rim onto the adjacent deep temporal fascia. Aging changes are associated with attenuation of the ligamentous support provided by the orbital thickening and the orbicularis retaining ligament, which then allows inferior displacement of the lower boundary of the lid and contributes to the typical effects of age in this region. The superficial fascia of the lateral orbital region has a continuous connective tissue structure linking the temporoparietal fascia and orbicularis fascia to the lateral canthal tendon by means of the tarsal plate connection. Release of the deep ligamentous attachments (lateral orbital thickening and orbicularis retaining ligament) of the orbicularis fascia is important in some canthopexy and in rejuvenation procedures. The release allows effective redraping and upward mobilization of the orbicularis of the lower lid and the premalar soft tissues.
Comparisons of clinical assessment with measurement of physical parameters are rare.
To standardize the horizontal wrinkling of the skin in order to define a reference chart of the different wrinkling grades and to propose an interpretation of the clinical pattern in terms of skin layers thickness and mechanical parameters.
A device allowing reproducible wrinkling of the skin was made. The skin folds created in this way were clinically assessed on women of different ages. Measurements of the mechanical properties of the skin were carried out by using a Torquemeter. Skin layers' thicknesses were measured by using in vivo Confocal Microscopy (CM) and Ultrasound Imaging (B mode).
Skin wrinkling grades increase versus age. Skin elasticity, extensibility and echogenicity decrease also versus age and the wrinkling grade. Wrinkling appears to be related to skin rigidification (for both stratum corneum and dermis) coupled to a certain weakening of the upper dermis (loss of echogenicity).
This study points out the key role of the age-related alterations of the upper dermis in skin wrinkling capacities.
This paper presents a computational model for studying the mechanical properties of skin with aging. In particular, attention is given to the folding capacity of skin, which may be manifested as wrinkles. The simulation provides visual results demonstrating the form and density of folds under the various conditions. This can help in the consideration of proper measures for a cosmetic product for the skin.
This prospective cohort study provides evidence and information on the mechanism of action of onabotulinum toxin A on the reduction of skin elasticity and pliability. Understanding the natural course that onabotulinum toxin A has on the elasticity of skin may help physicians understand why there appears to be a progressive reduction in wrinkle levels with repeated treatments.
To determine whether onabotulinum toxin A increases skin pliability and elasticity with a corresponding decrease in the contribution of the viscoelastic component of skin resistance.
From October 1, 2012, through June 31, 2013, this prospective cohort study enrolled 48 onabotulinum toxin A-naive women (mean [SD] age, 55.2 [11.3] years) with a minimum of mild wrinkle levels at the glabella and lateral orbit (43 completed the study). Patients were treated at a private cosmetic surgery clinic with onabotulinum toxin A and assessed at baseline and 2 weeks, 2 months, 3 months, and 4 months after injection.
Standardized onabotulinum toxin A was administered to patients' glabella, supraorbit, and lateral orbit.
Skin pliability, elastic recoil, and the ratio of viscoelastic resistance (Uv) to elastic resistance (Ue).
For the supraorbit, there was a significant effect of time on pliability (F = 20.5), elastic recoil (F = 6.92), and Uv/Ue ratio (F = 5.6) (P < .001 for all). For the glabella, there was a significant effect of time on pliability (F = 32.23), elastic recoil (F = 31.66), and Uv/Ue ratio (F = 10.11) (P < .001 for all). For the lateral orbit, there was a significant effect of time on pliability (F = 15.83, P < .001), elastic recoil (F = 11.43, P < .001), and Uv/Ue ratio (F = 10.60, P = .009).
This study provides further evidence that there is an alteration in biomechanical properties of the skin after injection with onabotulinum toxin A. This effect appears to last up to 4 months in the glabella and up to 3 months at other sites. The decrease in the Uv/Ue ratio suggests onabotulinum toxin A injection does not result in an increase in tissue edema suggestive of an inflammatory reaction within the skin. However, it remains unclear whether this is due to an intrinsic property of the medication or another unrecognized mechanism.
2.
Background: Light and electron microscopy have not identified a distinct anatomical structure associated with either skin wrinkles or creases, and a histological difference between wrinkled and adjacent skin has not been identified.
Objectives: The authors investigate whether facial wrinkles are related to underlying lymphatic vessels and perilymphatic fat.
Methods: Lymphatic vessels with a specialized tube of perilymphatic fat were identified beneath palmar creases. Sections of skin, adipose tissue, and muscle were harvested from each of 13 cadavers. Three sites were investigated: the transverse forehead crease, lateral orbicularis oculi wrinkle (crow's feet), and the nasojugal crease. The tissue was paraffin embedded and processed. Two-step indirect immunohistochemistry was performed, and images were examined using laser confocal microscopy. Measurements were taken with software.
Results: Every wrinkle examined was found above and within ±1 mm of a major lymphatic vessel and its surrounding tube of adipose tissue. The results satisfied our null hypothesis and were statistically significant. Lymphatic vessels were identified by positive immunofluorescence as well as histological criteria. These findings have been further validated by fluorochrome tracer studies.
Conclusions: An anatomical basis for wrinkles was identified among the specimens studied. Lymphatic vessels, along with the surrounding distinct perilymphatic fat, traveled directly beneath wrinkles and creases. Lymphatic dysregulation leads to inflammation, scarring, and fibrosis, but inadvertent injection of these vessels can be avoided with anatomical knowledge.
To determine whether there is an association between sleep position and the appearance of facial wrinkles and facial descent.
One hundred women were questioned about their sleep position preference. An independent expert observer evaluated frontal images with digital laterality randomization to identify the side with more wrinkles and more ptosis.
Forty-one right-sided sleepers and 23 left-sided sleepers were identified. There was statistical independence between sleep side and side with more wrinkles and between sleep side and side with more facial ptosis according to the Pearson chi-square test.
Sleep side preference was not significantly correlated with the appearance of wrinkles or facial descent.
The Dermal-Epidermal Junction (DEJ) is characterized by undulations whose apices are called papillae. With aging, epidermis becomes thinner, together with a flattening of the DEJ, leading to a decreased density of papillae. The causes of these modifications are likely as multiple as uncertain. The present paper deals with in vivo morphometric characterization of the DEJ and its changes following a skin surface deformation.
Living epidermis of human adults was examined by means of in vivo Reflectance Confocal Microscopy. Distances between skin surface and papillae apex and pegs of the DEJ were, respectively, recorded in both relaxed and stretched skin situation. The number of papillae present within a single image (field of view, 500 × 500 μm) was also measured.
Skin extension has no effect upon the distance between skin surface and the apex of papillae. In contrast, the distance between skin surface and the pegs of papillae decreases. On the other hand, skin extension leads to a significant decrease in the number of papillae within a single image.
Epidermal atrophy and structural changes observed in the DEJ with aging may be, by some extent, related to daily and repetitive skin deformations all along the life span.
Background:
External volume expansion by suction has been proposed to improve the survival of fat grafting by preparing the recipient site. In previous experimental work, external volume expansion demonstrated the capacity to stimulate cell proliferation, vessel remodeling, and adipogenesis. This study investigated possible mechanisms underlying these observed changes.
Methods:
A miniaturized external volume expansion device was applied to the dorsum of mice for 2 hours. Hypoxia during stimulation was assessed with pimonidazole hydrochloride, and tissue perfusion was measured for up to 2 days using hyperspectral imaging. Treated tissues were evaluated by microscopy for edema, inflammation, and the effects on cell proliferation and vessel remodeling.
Results:
External volume expansion-treated tissues were grossly expanded with 2 hours of stimulation, developing a macroscopic swelling that regressed slowly over the course of hours following stimulus cessation. This gross swelling was reflective of histologic signs of intense edema, persistent for at least 1 hour after external volume expansion. Tissues were hypoxic during stimulation, and hyperspectral imaging demonstrated decreased tissue content of both oxygenated and deoxygenated hemoglobin in the first hour after external volume expansion release. The onset of inflammation was already apparent by the end of stimulation and remained elevated through 2 days after external volume expansion. At this time point, epidermal and dermal cell proliferation and vascular density were significantly increased.
Conclusion:
External volume expansion sets in motion various mechanisms, including mechanical stimulation, edema, ischemia, and inflammation, that over distinct time periods maintain an environment conducive to cell proliferation and angiogenesis, which can be elicited even by a single 2-hour external volume expansion cycle.
This article discusses skin expansion without considering cellular growth of the skin. An in vivo analysis was carried out that involved expansion at three different sites on one patient, allowing for the observation of the relaxation process. Those measurements were used to characterize the human skin of the thorax during the surgical process of skin expansion. A comparison between the in vivo results and the numerical finite elements model of the expansion was used to identify the material elastic parameters of the skin of the thorax of that patient. Delfino's constitutive equation was chosen to model the in vivo results. The skin is considered to be an isotropic, homogeneous, hyperelastic, and incompressible membrane. When the skin is extended, such as with expanders, the collagen fibers are also extended and cause stiffening in the skin, which results in increasing resistance to expansion or further stretching. We observed this phenomenon as an increase in the parameters as subsequent expansions continued. The number and shape of the skin expanders used in expansions were also studied, both mathematically and experimentally. The choice of the site where the expansion should be performed is discussed to enlighten problems that can lead to frustrated skin expansions. These results are very encouraging and provide insight into our understanding of the behavior of stretched skin by expansion. To our knowledge, this study has provided results that considerably improve our understanding of the behavior of human skin under expansion.
Background:
The skin possesses unique biochemical properties that allow it to protect and conform to the body that it covers. Elements constituting the dermis-collagen and elastin-primarily afford these properties.
Objectives:
To define these properties and explore their relevance with regard to aging skin and dermatologic surgery.
Materials and methods:
In the first part of this review, the determinants of mechanical properties of the skin will be outlined, through an extensive review of the literature. General physical properties that explain the behavior of skin will be defined, and diseases that manifest the extremes of those properties will be discussed. In the second half of this discussion, the surgical implications of skin biomechanics will be reviewed.
Results:
Emphasis will be placed on understanding how dermatologic surgeons may optimally use skin properties to produce the best cosmetic and functional outcomes possible.
Conclusion:
Understanding of the biomechanical properties of skin is paramount to obtain the best cosmetic outcomes in dermatologic surgery.
Background:
The effects of hyaluronic acid (HA) injection on tissue collagen anabolism are suggested to be related to the induction of mechanical stress, causing biochemical changes in skin physiology.
Objectives:
To ascertain the association between dermal mechanics modulated by a hyaluronic acid-based filler effect and metabolism.
Methods:
Sixty females were randomised to receive a 0.5mL injection of HA gel or isotonic sodium chloride (control) in the arm. Skin biopsies were taken at baseline and after 1, 3 and 6 months. Protein and gene expression of procollagen, matrix metalloproteinases (MMP) and MMP tissue inhibitors (TIMP1) were measured blind by ELISA and qPCR, respectively. Injected volumes were measured by high-frequency ultrasound and radiofrequency analysis. Skin layer effects of injections were analysed by finite element digital modelling.
Results:
One month after injection, the filler induced an increase in procollagen (p=0.0016) and TIMP-1 (p=0.0485) levels and relative gene expression of procollagen III and I isoforms compared with the controls. After 3 months, procollagen levels remained greater than in the controls (p=0.0005), whereas procollagen expression and TIMP-1 and MMP content were no longer different. Forty-three percent of the injected filler volume was found at 1 month, 26% after 3 months and 20% after 6 months.
Limitations:
The ultrasound imaging technique limited the scope of the investigation and precluded an evaluation of the action of the filler at the hypodermic level.
Conclusions:
Integrating both mechanical and biological aspects, our results suggest that mechanical stress generated by cross-linked HA plays a role in dermal cell biochemical response.
Skin mechanical properties are globally well described. The aim of this paper is to evaluate, by means of a numerical model, the influence of Stratum Corneum (SC) on skin folding resulting from an in-plane compression.
A computational skin model was developed where skin is divided into three layers (SC, epidermis and upper dermis, and deep dermis) of different thicknesses and elastic moduli. Skin surface deformation, consecutive to the application of a given surface compression, was computed by minimizing the mechanical energy of the multi-layered tissue. Influence of SC thickness and elastic modulus on skin buckling is presented.
Varying both SC thickness and elastic modulus has a marked influence on both wavelength and amplitude of the skin's surface folds. These two parameters display a logarithmic variation versus SC elastic modulus.
Although representing about one hundredth of the total skin thickness, SC has a marked influence on the skin mechanical properties.
Although there have been many studies investigating facial movements using three-dimensional (3D) quantitative analysis, the possible relationship between the levels of wrinkles and the movement distance of facial skin has previously not been reported.
Forty-four healthy Japanese women (from 20 to 50 years, average = 47.7 ± 3.6 years) were recruited for this study with written informed consent. Infrared reflective marks were attached on their forehead skin, and then moving images of facial skin motions (raising the eyebrows) were captured using two infrared cameras under infrared ray irradiation. Calibration for the absolute value of distance was established using an exact one-point 3-m cube having infrared reflective marks at each apex. The two pupils and the top of the nose were setup as fixed standard points. 3D motion analysis was then carried out using Move-tr/3D™ software to determine the absolute distances of skin surface movements. Levels of wrinkles were determined using a 3D roughness analyzer (PRIMOS™) directly at rest and when raising the eyebrows.
The wrinkle levels at rest showed a relatively high and significant correlation with wrinkles when strongly raising the eyebrows. Although the wrinkle levels at rest showed no correlation with the movement distance, the wrinkle levels when raising the eyebrows showed a significant correlation with the movement distance. The ratio of change based on the distance between the marks at rest and when raising the eyebrows showed similar correlation results.
These results suggest that both the levels of skin deformation caused by movements and the wrinkles at rest are important factors that determine the wrinkle level when raising the eyebrows. However, the level of skin deformation is not important for wrinkle levels at rest, which indicates that other factors such as skin elasticity are also important for the formation of wrinkles.
The goal of the described study was complex assessment of age-specific morphofunctional features of skin of different anatomic localization using optical coherence tomography (OCT).
Forty-three healthy volunteers aging from 4 to 74 years were enrolled in the study. Optical and functional skin parameters were studied in 18 areas of the human body. All the studied areas were classified as open and closed, depending on external impact. Structural parameters of skin were determined by means of the OCT device equipped with a removable, flexible probe with microscanner (registration certificate no. 022a2035/2213-05) designed and fabricated at the IAP RAS (Nizhny Novgorod, Russia) with longitudinal and transverse resolution of about 20 μm.
Age-specific morphofunctional features of skin most evident in areas exposed to external action were found. Statistically significant difference in elasticity (−0.57, P = 0.00012) in areas closed to external action (further referred to as closed areas) and in useful signal depth, hydration and elasticity in areas exposed to external action (further referred to as open areas) was assessed for different age groups. Analysis of the dependence of parameters on age showed statistically significant correlations between age and thickness of cellular layers of the epidermis (−0.33, P = 0.035), pigmentation level (−0.22, P = 0.044) and elasticity in closed areas and highly significant correlations between age and hydration and elasticity in open areas.
The current work is concerned with investigation of age-specific morpho-functional parameters of skin of different localizations.
Synopsis
Wrinkles result from distinct structural changes occurring in specific parts of the dermis and subcutaneous tissue. There is a need for evidenced‐based cosmetology identifying and quantifying the different aspects of wrinkling. Histology allows to detect specific changes associated with particular types of wrinkles. Four main types of wrinkles can thus be recognized, including the atrophic crinkling rhytids, the permanent elastotic creases, the dynamic expression lines, and the gravitational folds. Each type usually develops on specific skin regions exhibiting distinct microanatomical characteristics. Whereas skin microrelief, expression lines and skin folds appear clearly marked at the histological level, only little dermal changes are identified under other reducible or permanent wrinkles compared with the skin immediately adjacent to them. Distinguishing different types of wrinkles brings more precision to the clinical practice. This is of importance because the different types of wrinkles respond differently to cosmetic, dermatological and surgical treatments.
Various skin parameters including skin visco-elasticity and hydration level affect the formation of wrinkles.
The aim of this study was to investigate the comprehensive and objective relationship between age, skin visco-elasticity, hydration level, and the occurrence of wrinkles using bioengineering equipments for the first time.
A total number of 97 healthy women were included in this study. Age, Fitzpatrick skin type, skin mechanical parameters obtained with Cutometer®(R0~R9), hydration level measured with Corneometer®, as well as wrinkle parameters (SEsm, SEr, SEsc, and SEw) assessed with Visioscan®, were analyzed with the Pearson's correlation test.
The skin fluidity (R6) increased while the elastic recovery ratio (R7) decreased with the age. The wrinkle parameter (SEw) also increased with the age. The higher skin hysteresis values (R4 and R9) coincided with the higher SEw values. Skin hydration significantly lowered the hysteresis (R9), the wrinkles (SEw), and the depth of wrinkle furrows (R3mr).
The elderly have less elastic skin and more wrinkles. Skin hysteresis most closely related with the degree of wrinkles. Drier skin showed more wrinkles and deeper furrows, with wider intervals. On the basis of these objective findings, we propose several skin parameters associated with wrinkles, and hypothesize the mechanism of wrinkle generation.
Objectives:
To define normal values for total sleep time, sleep latency, sleep efficiency, sleep stages and sleeping positions in women and to investigate how sleep is affected by age, obesity, sleep apnea, smoking, alcohol dependency and hypertension.
Methods:
In a population-based study, 400 Swedish women aged 20-70 years with over-sampling of snorers were investigated using overnight in-home polysomnography. All results are weighted.
Results:
The mean normal total sleep time was 392 min, sleep latency 22 min and sleep efficiency 82%. Women spent 31 min in sleep stage 1, 244 min in stage 2, 41 min in stage 3/4 and 76 min in rapid eye movement (REM) sleep. They spent 41% of their sleep time in the supine position, 50% in the lateral position and 9% in the prone position. Multivariate analyses revealed that sleep efficiency was lower in older women and in women with hypertension. Sleep latency was short in women with severe sleep apnea and long in smokers, alcohol-dependent and hypertensive women. Sleep stage 3/4 was inversely related to age and body mass index. Less REM sleep occurred in alcohol-dependent women. Women younger than 45 years old slept a mean of 42% in the lateral position while women of 45 years and older slept 57% in the lateral position (p<0.001).
Conclusions:
In this population-based study of women, we present normal values for sleep stages and sleeping position. We conclude that age, body mass index, obstructive sleep apnea, smoking, alcohol and hypertension reduce sleep quality. With age, women spend more time sleeping in the lateral position.
Does the morphology of wrinkles alter gradually with aging or suddenly at a certain age? On the basis of the theoretic wrinkle simulation of ideal skin, we have suggested that the wrinkle morphology suddenly changes from stratum corneum wrinkling to epidermis wrinkling; the former induces shallow fine furrows, and the latter induces deep prominent wrinkles. To examine the existence of drastic change in wrinkling morphology, we developed a new measurement system for facial skin wrinkling test.
The mechanical compression test of facial skin was carried out for 102 Japanese women aged 25-56 years. The test was performed on the right temple area skin, and the area of wrinkles induced by the compression was measured using a digital video camera. The rate of increase in wrinkle area during compression was defined as the skin wrinkling rate, and it was calculated for all subjects automatically by image processing.
The test results showed that the skin wrinkling rate underwent a step increase at the age 33, which means that the wrinkling morphologies of young and old skins are completely different, and so it changes suddenly in the early 30s.
A new skin measurement system was developed to validate our theory of wrinkle formation mechanism with aging. The results demonstrated the wrinkling morphology changes suddenly at early 30s.
Background:
The possible relationship between the direction of wrinkles and the movement of facial skin has not previously been reported. Therefore, we characterized that relationship using particle image velocimetry (PIV) analysis.
Method:
Twenty-one healthy Japanese women aged in their 20s (n = 7) or 50s (n = 14) were recruited for this study. Moving images of facial skin motions (closing the eyes tightly, raising the eyebrows) were captured using a single infrared camera under infrared ray irradiation of the skin. PIV analysis was then carried out using Flow-Vec32 software to determine the velocity and the direction of skin surface movements.
Results:
All skin movements caused by those motions were finished within 0.20 s. During the motion of closing the eyes, skin at the eye periphery did not move in a superior-inferior direction, but did move toward the center of the eye (pupilla) with complex flows. There was no significant difference between either age group of subjects. During the motion of raising the eyebrows, the forehead skin moved upwards (direction to parietal) with relatively uniform flows. The velocity of movement at the top was lower than at the bottom, and that difference is likely to cause a deformation on the skin surface. A significant difference between the two age groups in the velocity was observed.
Conclusion:
The results show that the deformation of older skin on the forehead is greater than that in younger skin. The PIV analysis method is a useful tool to investigate some aspects of the relationship between facial skin movements and wrinkle formation.
To study the changes in skin microrelief and periocular wrinkles during the aging process.
Replicas of the crow's feet area of volunteers were recorded in 1987 and 2008 and observed comparatively. Characteristic features were quantified by image analysis.
Observation shows that some microrelief features disappear and even merge with wrinkles that become more marked. Some primary lines also tend to merge to form thin new wrinkles. Quantitative data support these observations: the size of small and medium objects of skin relief decreases with age while large objects are becoming larger.
Over 21 years, in the group studied, the total area of the detected objects remains quite constant. Only the distribution between small and large detected objects (microrelief features and wrinkles, respectively) is modified.
The mechanical aspects of wrinkle formation were studied in the dorsal skin of hairless mice.
Wrinkles were induced by irradiating with ultraviolet (UV) B for 10 weeks, while observing skin deformation during wrinkle formation. Changes in skin dimensions were also observed during the specimen excision process. Wrinkle depth and interval were measured before and after removal of the cutaneous muscle layer. Local deformation of wrinkled skin during uniaxial stretch was also measured. Changes in curvature of skin specimens upon muscle layer removal were then observed to determine the force balance in skin layers.
The skin showed spontaneous contraction in response to UV irradiation. Wrinkled skin showed a marked decrease in the wrinkle depth and a slight increase in wrinkle interval following muscle layer removal, a peculiar mechanical response that cannot be explained by homogeneous deformation of the skin. This response was due to compressive deformations of dermal tissue caused by the muscle layer and concentrated at valleys of the wrinkles. Curvature measurements indicated that the muscle layer compressed the dermal tissue predominantly in the craniocaudal direction. Morphological observations showed that the wrinkles coincided with rows of pores and sulci cutis, where the structural stiffness of the horny layer was relatively low. The horny layer showed significant thickening.
Taken together, we propose the following hypothetical mechanisms of wrinkle formation during UV irradiation: spontaneous contraction of the dermis while maintaining or increasing the epidermal area induces buckling of the epidermis into the dermis at mechanically weak lines, namely, the rows of pores and sulci cutis, and buckling may be amplified by the axial compression of the dermis by the muscle layer.
While cumulative lifetime sun exposure is well recognized as having an important role in the progression of facial wrinkling, the role of facial expression has largely been overlooked, in part due to the lack of comprehensive longitudinal data on the change in both expression lines and persistent wrinkles with age.
To track the detailed pattern of facial wrinkling in the same group of people over several years and to verify that expression lines evolve into persistent wrinkles. In addition, to identify factors predictive of a faster or slower rate of wrinkling.
Standardized images were captured at baseline and at 8 years of 122 women (ages 10-72 years, skin types I-VI) with and without a smiling expression. The wrinkle pattern with expression at baseline was compared with the pattern without expression at 8 years. Severity of facial wrinkling was quantified using computer-based image analysis. Skin colour, hydration, sebum and pH were measured at baseline. A structured questionnaire captured demographic and lifestyle data at baseline and at 8 years.
Each subject's unique pattern of persistent facial wrinkling observed without expression at year 8 was predicted by the pattern of lines observed with a smiling expression at baseline. Having a drier, more alkaline stratum corneum, a lighter complexion, being middle-aged (40s) or becoming menopausal were associated with faster persistent wrinkling.
Repeated skin flexure during facial expression causes persistent wrinkles. The pattern of expression lines predicts the pattern of future persistent wrinkles. Certain intrinsic and extrinsic factors are not causative, but influence the rate, of facial wrinkling.
Learning Objectives: The reader is presumed to have a basic understanding of facial anatomy and facial rejuvenation procedures. After reading this article, the reader should also be able to:
Identify the essential anatomy of the face as it relates to facelift surgery.Describe the common types of facelift procedures, including their strengths and weaknesses.Apply appropriate preoperative and postoperative management for facelift patients.Describe common adjunctive procedures.
Physicians may earn 1.0 AMA PRA Category 1 Credit™ by successfully completing the examination based on material covered in this article. This activity should take one hour to complete. The examination begins on page 464. As a measure of the success of the education we hope you will receive from this article, we encourage you to log on to the Aesthetic Society website and take the preexamination before reading this article. Once you have completed the article, you may then take the examination again for CME credit. The Aesthetic Society will be able to compare your answers and use these data for future reference as we attempt to continually improve the CME articles we offer. ASAPS members can complete this CME examination online by logging on to the ASAPS members–only website (http://www.surgery.org/members) and clicking on “Clinical Education” in the menu bar.
Modern aesthetic surgery of the face began in the first part of the 20th century in the United States and Europe. Initial limited excisions gradually progressed to skin undermining and eventually to a variety of methods for contouring the subcutaneous facial tissue. This particular review focuses on the cheek and neck. While the lid–cheek junction, eyelids, and brow must also be considered to obtain a harmonious appearance, those elements are outside the scope of this article. Overall patient management, including patient selection, preoperative preparation, postoperative care, and potential complications are discussed.
The mechanical properties of human skin are known to change with ageing, rendering skin less resistant to friction and shear forces, as well as more vulnerable to wounds. Until now, only few and contradictory results on the age-dependent friction properties of skin have been reported. This study has investigated in detail the influence of age on the friction of human skin against textiles.
In vivo skin-friction measurements on a force plate were combined with skin analyses concerning elasticity, hydration, pH value and sebum content. Thirty-two young and 28 aged persons rubbed their volar forearm in a reciprocating motion against various textiles on the force plate, using defined normal loads and sliding velocities, representing clinically relevant contact conditions.
Mean friction coefficients ranged from 0.30 +/- 0.04 (polytetrafluoroethylene) to 0.43 +/- 0.04 (cotton/polyester). No significant differences in the friction properties of skin were found between the age groups despite skin elasticity being significantly lower in the aged persons. Skin hydration was significantly higher in the elderly, whereas no significant differences were observed in either skin pH value or sebum content.
Adhesion is usually assumed to be the dominant factor in skin friction, but our observations imply that deformation is also an important factor in the friction of aged skin. In the elderly, lower skin elasticity and skin turgor are associated with more pronounced skin tissue displacements and greater shear forces during frictional contact, emphasizing the importance of friction reduction in wound-prevention programmes.
Aging of skin is accompanied by decrease of skin elasticity. Using the noninvasive suction device Cutometer, we evaluated the age and regional body differences of the viscoelastic properties of human skin. The objectives of this study were to evaluate the correlation between age and the biomechanical parameters and the regional skin variations.
A total of 96 healthy women aged 20-75 years were included in this study. The biomechanical properties of the skin were measured by using the Cutometer. Measurements were made on the face, upper arm and back.
The age of subjects showed significant positive correlation with R4 and R6, and negative correlation with R2, R5 and R7. The face showed bigger changes of elastic properties than the arm and the back. Especially, the R7 of face was most significantly decreased with aging. We could estimate the so-called 'skin age' by using a correlation equation for this parameter.
The viscoelastic properties were significantly influenced by aging. Also, significant regional variations in the viscoelastic properties were observed. Skin elasticity measurement is useful for the quantitative evaluation of age-related changes.
The zygomatic ligaments (McGregor's patch) anchor the skin of the cheek to the inferior border of the zygoma just posterior to the origin of the zygomaticus minor muscle. The mandibular ligaments tether the overlying skin to the anterior mandible. Both these ligaments are obstacles to surgical maneuvers intended to advance the overlying skin. They also restrain the facial skin against gravitational changes, and they delineate the anterior border of the "jowl" area. The platysma-auricular ligament is a thin fascial sheet that extends from the posterosuperior border of the platysma and that is intimately attached to the periauricular skin; it serves as a surgical guide to the posterosuperior border of the platysma. The anterior platysma-cutaneous ligaments are variable fascial condensations that anchor the SMAS and platysma to the dermis. They can cause anatomic disorientation with dissection of false planes into the dermis. These four ligaments are useful as anatomic landmarks during facial dissections. The tethering effects of the zygomatic and mandibular ligaments must be interrupted if a maximum upward movement of the facial skin is desired.
The anatomy of linear wrinkles ("crow's feet' and temporal frown lines), fine criss-cross wrinkles of the face and wrinkling of the general body surface of elderly persons, was studied by light and scanning electron microscopy. No histological features distinguished the various wrinkles from surrounding skin. It was concluded that the wrinkle is a configuration change, like the grooves worn into an old glove, without specific structural alterations at the histological level. As regards pathogenesis, the common setting was found to be deterioration of the elastic tissue network. The skin becomes looser, excessive, and loses the ability to snap back to its original state after being deformed.
Using recently designed, commercially available, non-invasive instruments, we measured the thickness and elasticity of the skin of the face and ventral forearm in 170 women, and evaluated the effects of age and exposure to sunlight. Skin thickness decreased with age in ventral forearm skin, which has limited exposure to sunlight, but increased significantly in the skin of the forehead, corners of the eyes, and cheeks, which are markedly exposed to sunlight. Skin elasticity (Ur/Uf) decreased with age on both the face and forearm. The ratio of viscosity element to elasticity element (Uv/Ue) increased with age at all sites. However, delayed distension (Uv), immediate retraction (Ur), final distension (Uf), and immediate distention (Ue), as individual elements, decreased on the face and increased on the forearm with age. This tendency was more marked after correction for skin thickness. These results suggested the specificity of skin thickness and elasticity in the facial skin. Analysis using a four-element model showed no changes in the elasticity coefficient of Maxwell element on the forearm, but an increase on the face. This indicates quantitative or qualitative changes in elastic fibres in facial skin. Thus, sunlight appears to have a considerable effect on the thickness and physical properties of facial skin.
One of the most interesting medical conditions that now afflicts the baby boomer generation is photoaging. Clinical signs of photoaging of the skin include rhytids, lentigines, keratoses, telangiectasia, loss of translucency, loss of elasticity, and sallow color. A systematic classification of patient photoaging types has been developed by the author: type I, "no wrinkles"; type II, "wrinkles in motion"; type III, "wrinkles at rest"; and type IV, "only wrinkles." The intent is to organize the discussion of therapies for photodamaged skin to permit rational comparisons of therapies and clinical results.
This is a tribute to Dr. Samuel J. Stegman who in 1987 described "Sleep Creases." His awareness of these lines has helped us understand the anatomy of the underlying superficial musculoaponeurotic system (SMAS).
To expand upon the clinical description and the anatomical basis of sleep lines.
A pillow or hand test is used to accentuate sleep lines. Their development is linked to the underlying attachments of the SMAS.
There is a correlation between the location of the underlying SMAS or aberrant scar tissue and sleep lines. To effectively treat these lines, the sleeping position must be altered or subcision of the underlying SMAS attachments and skin resurfacing may improve the situation.
We have confirmed Dr. Stegman's hallmark work on sleep wrinkles. They are accentuated by pillow contact and the underlying SMAS.
We studied the relationship between sleep quality and bed surface firmness. Nine men were investigated, sleeping in their homes for at least 5 consecutive nights on a soft and a more firm mattress using a sensor pad placed under the mattress and a solid-state recording device. The subjective feeling of sleep quality did not always agree with the recorded sleep data. The difference was most marked when changing from the subject's own to one of the test mattresses. For the same subject the results were reproducible between nights provided there were no external disturbing factors. Four of the 9 subjects slept significantly better on the softer of the two mattresses and 2 on the hard mattress. The difference in sleep quality observed among the subjects tested makes it necessary to relate the results to the same person rather than considering a whole group as an entity. The adaptation period for a new sleep surface extended to many days.
The body posture and gravitational forces govern in part the intrinsic skin tensile strength because they influence the orientation of the dermal fibre networks. Our objective was to assess changes in shear wave propagation in the skin according to the body posture and orientation of the gravitational forces. The study was performed in 30 middle-aged women with a normal body mass index. The Reviscometer was used to assess the mechanical wave propagation on the volar forearm in extension or flexion. Similar measurements were made on the supra-areolar region of the breast when the trunk was in the horizontal or vertical position. Four measurements were made in each of 4 directions at given angles with regard to the body axis. The device gave reproducible data. Shear wave propagation was influenced by the body posture. The intra-individual variability in shear wave velocity according to the directions of measurements increased when the tissues were in a relaxed position. Skin tensile anisotropy increased in a relaxed body posture. Shear wave propagation may be a convenient non-invasive tool to better identify the natural skin tension lines in the skin, thus refining the orientation of incision during cutaneous surgery.
Noninvasive methods have allowed physicians to give an objective description of aged skin in terms of functional and esthetic properties. The relative influence of environment (mainly sun) on the true aging process can be assessed through the obtained data. It is also possible to measure the efficacy of topical preparations (cosmetics or drugs) designed for treating the various cutaneous aging marks.
The influence of mechanical forces on skin has been examined since 1861 when Langer first reported the existence of lines of tension in cadaver skin. Internal tension in the dermis is not only passively transferred to the epidermis but also gives rise to active cell-extracellular matrix and cell-cell mechanical interactions that may be an important part of the homeostatic processes that are involved in normal skin metabolism. The purpose of this review is to analyse how internal and external mechanical loads are applied at the macromolecular and cellular levels in the epidermis and dermis.
A review of the literature suggests that internal and external forces applied to dermal cells appear to be involved in mechanochemical transduction processes involving both cell-cell and cell-extra-cellular matrix (ECM) interactions. Internal forces present in dermis are the result of passive tension that is incorporated into the collagen fiber network during development. Active tension generated by fibroblasts involves specific interactions between cell membrane integrins and macromolecules found in the ECM, especially collagen fibrils. Forces appear to be transduced at the cell-ECM interface via re-arrangement of cytoskeletal elements, activation of stretch-induced changes in ion channels, cell contraction at adherens junctions, activation of cell membrane-associated secondary messenger pathways and through growth factor-like activities that influence cellular proliferation and protein synthesis.
Internal and external mechanical loading appears to affect skin biology through mechanochemical transduction processes. Further studies are needed to understand how mechanical forces, energy storage and conversion of mechanical energy into changes in chemical potential of small and large macromolecules may occur and influence the metabolism of dermal cells.
Plastic surgery must achieve the best cosmetic results, and it helps to consider certain skin lines. Aging and scars can cause the face to become lined, and we have noticed various facial lines among patients or their relations who have come to our outpatient clinic. These lines are sometimes single and there are sometimes 2-3 parallel lines generally in the same area of the face, such as the lateral orbital, temporal, frontal, and buccal regions. After detailed evaluation, we concluded that these oblique or horizontal wrinkles were caused by the position in which they slept. All of them slept prone, with their faces buried in the pillow, which over many years has caused wrinkling of the skin. We think therefore that sleeping position should be considered as an aetiological factor in the formation of wrinkles. The lines that should be taken into consideration during operation are Langer's lines, or relaxed skin tension lines, but not sleep lines. Here we describe the possible aetiology of sleep lines on the face.
The age-related decrease of skin elasticity results in larger fatigue of adult skin than young skin after applying multiple stress at one and the same anatomic region. The aim of this study was to compare the informativeness of Cutometer standard R-parameters with new area parameters regarding the age-related changes in human skin fatigue.
A total of 40 healthy volunteers aged 12-82 years were studied. Mechanical parameters of the skin were determined using a non-invasive suction skin elasticity meter (Cutometer). Measurements were made on the temporal region and volar forearm. Skin mechanical parameters analyzed by Win-Cutometer MPA software were R3, R4 and R9 (R-parameters), and F2 and F3 (area parameters).
The adult skin was characterized by significantly higher values of R4, R9 and F2, and lower F3 compared with young skin. R3 was not significantly altered. There were not any sex-related differences. F2 correlated positively with parameters R3, R4 and R9, while F3 correlated negatively with R4. A positive correlation within the parameters R3, R4 and R9 was established at both anatomic regions.
The non-invasive method applied can be useful for objective and quantitative investigation of age-related changes in skin fatigue and evaluation of the effects of cosmetic and anti-aging topical products. The mechanical parameters R4 and F3 are most indicative of human skin fatigue.
Most studies of how the relief of the skin surface changes on ageing are based solely on topography, and a few have taken into account anisotropy parameters. However, the calculation of these parameters is often carried out manually and as the techniques of data acquisition have progressed rapidly, a certain degree of obsolescence has been reached. It is for this reason that we have undertaken a similar study but with more advanced equipment.
The Dermatop system analyses the relief of Silflo negative prints of the skin surface. It is based on the projection of interference fringes and phase shift and provides surface parameters and not profiles. In addition, the Toposurf software enables image processing and the precise and automatic calculation of the topography parameters (roughness, developed surface area and peak-trough amplitude) and anisotropy (level of anisotropy and furrow density). These parameters were studied on the forearm and temple of 40 men and 40 women evenly distributed into two groups: the first including subjects aged 25-35 years and the second 50-65 years.
Roughness of both sites increases with age, independent of sex, but to a lesser extent in women than in men. The developed surface area and the peak-trough amplitude increase significantly with age irrespective of the site and the sex. The level of anisotropy increases with age, in both men and women, on the forearm and the temple, the site more exposed to light being more affected. The density of the furrows decreases with age in both sexes and both sites but with a greater increase for the temple, which is more exposed to solar ageing.
The study of these new parameters will allow objective evaluation of the action of topical dermatological and cosmetic treatment, and new techniques in plastic surgery (e.g. laser resurfacing), and will enable the accurate follow-up of certain pathologies.
This paper explains how the shape of the spine can be evaluated from back surface measurements in a recumbent position, by using point distribution models (PDM) and typical shape variability of the spine in a lateral sleeping position. CT-scans of 12 volunteers were taken in this posture on a firm and a soft sleeping system to provide a training set for the PDM. Active shape models (ASM) were used to enhance the accuracy of the spinal reconstruction from measurements by limiting the shape of the spine to characteristic shapes from a biomechanical and/or clinical point of view. A comparison was made between calculated shapes, obtained from surface measurements, and those measured vertebral body centres (from CT-scans). An RMS accuracy of 2.6mm was obtained in 3D, and 1.8mm in frontal view, which was sufficient to compare spinal deformations of a subject on different sleeping systems.