Additional methods of skin assessment

In modern cosmetology, various additional non-invasive methods of skin condition assessment are widely used both for the purpose of diagnosing certain diseases and conditions, and for the purpose of assessing the effectiveness of various cosmetic products or procedures. Such methods are becoming increasingly popular in both scientific research and daytime practical activities, due to the fact that in the latter, much attention is paid to the standardization of the assessment of the effect of cosmetic products and procedures.

To assess the dynamics of changes against the background of various medical and cosmetic procedures, the method of photo documentation is popular. When photographing the skin, it is important to use the correct standard lighting of the skin; it is also recommended to take frontal and lateral shots.

In order to detect characteristic glow in fungal and infectious diseases or changes in skin color in pigment disorders and a number of inflammatory dermatoses, examination in a fluorescent lamp with a Wood filter is widely used. With the help of modern devices (VisioFace®, CK electronic), they also use photographing a skin area in the "white range" and under ultraviolet light, which is important for diagnosing a number of pigment formations and photodamage to the skin.

In recent years, a method has been used to study the optical properties of skin in normal and pathological conditions, which consists of assessing the condition and changes in the intensity of skin fluorescence, in particular sebum, caused by porphyrins.

In dermatocosmetology, the assessment of the skin relief (texture) is relevant. Skin relief refers to the depth and width of grooves, as well as the size of other irregularities on the skin surface. Skin relief is one of the most important parameters of its functional state. The relief is assessed using a skin-visiometer, which determines the depth and height of various points depending on how they absorb and reflect light. In addition, a method is used to remove a silicone mold from the skin surface and then examine it using a very thin diamond needle.

To study the skin microrelief, a method such as superficial biopsy of the stratum corneum is used. The advantages of the method are simplicity, non-invasiveness, and painlessness. The method allows one to estimate the rate of desquamation, study the ratio of active and inactive follicles. A film with special disks and cyanoacrylate glue applied to the skin surface is removed together with the corneocytes after the glue dries. The material fixed to the glue is stained using histological, microbiological, and histochemical methods. If it is necessary to study the intensity of corneocyte staining, chromometry is used, and their size and shape are studied using morphometry. Currently, both classical methods and immunomorphological, immunohistochemical, and electron microscopic studies of corneocytes are used. The latter method also provides information on the nature of the microflora on the skin surface.

The skin pattern and distinctive features of a number of rashes are examined using dermatoscopy. An enlarged (up to 90) image of a skin area is transmitted to a monitor for analysis, and the exact dimensions, borders, color, surface texture of elements, and some intraepidermal (intradermal) structures are assessed. Dermatoscopy is used for early diagnosis of benign and malignant skin neoplasms, including melanoma-hazardous nevi, premelanomas, and melanomas.

Litmus paper was previously used to determine skin acidity. This method is now practically not used due to the high risk of developing dermatitis and the dubiousness of the results obtained. An electrochemical method using a pH meter, or pH-metry, is used. The principle of operation is based on measuring the potential difference between the buffer solution and the hydrolipid mantle of the skin area being examined. Computer processing and recalculation of voltage values into pH values with an accuracy of one tenth allow obtaining data on the acid-base state of the hydrolipid mantle of the skin.

When assessing the degree of skin hydration, the moisture content of the stratum corneum is measured using a corneometer. The principle of operation of the device is based on the study of electrical conductivity. The higher the electrical conductivity of the skin, the higher its moisture content. The measuring probe has two electrodes - positive and negative charges. There is a dielectric between them. When in contact with the skin, an electric current is generated between the electrodes, and its strength determines the electrical conductivity and, accordingly, the moisture content of the skin. The advantage of the method is its simplicity. The disadvantages include the risk of developing dermatitis at the site of contact with electrolytes.

The evaporimeter device can provide important information about the hygroscopicity and barrier properties of the skin by measuring the amount of water absorbed by the skin and the speed at which it gives it up (transepidermal water loss - TEWL). The intensity of this process is studied using a probe equipped with special sensors. A serious drawback of the method is the dependence of the measurement results on the slightest fluctuations in air and its temperature.

Cutometry is used to study skin elasticity. A special optical measuring system processes information about the skin area located in the probe hole, the results are recorded on the monitor in the form of an elasticity curve (in hundredths of a millimeter). The cutometer also determines the degree of damage to collagen and elastic fibers. The disadvantage of the device is that it can only assess elasticity in a separate area of the superficial layer of the skin.

Often in cosmetology there is a need to evaluate the activity of the sebaceous glands. Determining the exact amount of sebum on the skin surface is called sebometrics. On the head of the measuring cassette there is a special opalescent plastic film, which is applied to the skin for 30 seconds. Then the cassette is placed in a sebometer-photometer and studies the fat imprint. The principle of spectrophotometry is used: the result depends on the intensity of absorption of light radiation by the fat imprint.

The lipometry method is similar in its essence to sebometrics. It allows determining the amount of sebum on the surface of uncleaned skin (baseline). The presence of a dynamometer allows for standardized glass pressure on the skin surface. The use of standard calibration (mg lipid/sm2 ⁾ in the study facilitates comparative analysis of the study results. The sebum content of normal skin is 100-200 mg lipid/sm2 ^, oily skin - more than 500 mg lipid/sm2 ^, dry skin - 50 mg lipid/ ^sm2.

The Sebutape method involves the use of special films made of hydrophobic microporous polymer with an adhesive surface. The film is applied to clean skin with an exposure of 20-30 minutes. The area of the fat spot formed as a result of the penetration of secreted lipids through the adhesive layer into the micropores is directly proportional to the secretory activity of the sebaceous glands. Normally, the resumption of sebum secretion is, according to this method, 0.6-2 mg / (sm ² • min).

Currently, ultrasound diagnostics of the skin is widely used, allowing us to assess the degree of hydration, the state of collagen and elastic fibers of the dermis.

Thermometry is used to assess the state of skin microcirculation. This method is based on the effect of decreasing tissue temperature when their perfusion is impaired. The advantages of the method are the ability to conduct numerous repeated studies. The disadvantage of the method is that the temperature change is quite inert even in the absence of blood flow. Liquid crystal thermography is a good method for diagnosing circulatory disorders in cellulite. It allows visualizing and measuring temperature fields and heat flows corresponding to the intensity of microcirculation of a particular part of the body. In this case, hypo- and hyperthermal areas are recorded by encapsulated liquid crystals located in flexible thermographic plates in the form of foci of a certain color, size and shape.

Microcirculation of the skin can also be assessed using ultrasound Dopplerography. The dynamics of blood flow in the microcirculatory bed are studied, determining its linear and volumetric speed. The method is based on recording the movement of erythrocytes in the vessels of the skin. The resulting signal is transformed into sound or graphic. The principle of laser Doppler flowmetry is based on recording the spectral scattering of a monochromatic light beam by moving blood cells. Ultrasound Dopplerography and laser flowmetry can be used for long-term dynamic observation. The methods are widely used in plastic surgery to assess the state of microcirculation before free flap plastic surgery, as well as to assess the state of microcirculation of the distal parts of the extremities in onychodystrophy. In some cases, clinicians supplement Doppler studies with pharmacological tests with acetylcholine (endothelium-dependent vasodilation) and nitroglycerin (endothelium-independent vasodilation) to determine vascular reactivity, which significantly expands the capabilities of the described methods.

Widely used nail bed capillaroscopy allows to evaluate a number of important static and dynamic parameters of microcirculation. The method began to be used to characterize blood circulation in age-related skin changes.

Radioisotope examination provides objective information about tissue blood supply. It is used in plastic surgery to determine the viability of autotransplants. The capabilities of this method are significantly limited by radioactive safety measures.

Impedance rheoplethysmography records changes in the electrical resistance of soft tissues when their blood filling fluctuates. The method is based on measuring the total resistance of alternating current at different frequencies with subsequent determination of the polarization coefficient

It is used to monitor the skin condition after peeling procedures. Micro plethysmography determines the blood filling of capillaries. In recent years, mexametry, or capillary metry, has been used to assess the functional state of capillaries, determining the diameter of the cross-section of capillaries in dynamics, studying the state of microcirculation by the degree of expression of blood filling of capillaries.

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