ABSTRACT
BACKGROUND/AIM: The decrease of skin elasticity on the cheek is a major concern to woman. The Cutometer has been widely used to evaluate skin elasticity and its change with aging. Cutometer parameters derived from one suction have been traditionally used to evaluate skin elasticity, and few reports describe the use of multiple suctions to obtain parameters to assess the skin elasticity of the cheek. To find the most suitable Cutometer parameter that reflects age-related changes in the elasticity of cheek skin using multiple suctions. METHODS: The cheeks of 32 healthy Japanese women (mean age, 42.3 years) were assessed using the Cutometer MPA580 by measuring the skin mechanical parameters R0-R9, F2 and F3. Parameters F2 and F3 were obtained by the multiple suction method. The relationship between age and these parameters were then examined. RESULTS: Significant negative correlations were found between the age of subjects and R2, R3, R7, R8 and F3. Of these, the correlation coefficient was best between age and F3 (r = -0.641), followed R8 (r = -0.603). CONCLUSION: Although R parameters have been used to evaluate skin elasticity, our study showed that F3 parameters derived from multiple suctions appear to be suitable for evaluating the elasticity of cheek skin, since this parameter is less influenced by environmental factors compared with R parameters.
Subject(s)
Cheek/pathology , Elasticity Imaging Techniques/methods , Skin Aging/pathology , Skin/pathology , Adult , Biomechanical Phenomena , Cosmetic Techniques , Elasticity , Female , Humans , Middle Aged , Skin Physiological PhenomenaABSTRACT
BACKGROUND/AIMS: The interpretation of patch test reactions may vary between examiners. As test results are graded, an issue also arises when differing degrees of erythema are placed in the same grade. The purpose of this study was to quantitatively evaluate the degree of erythema in patch tests using image analysis and to study the usefulness of this method by comparing it with visual grading. METHODS: A total of 121 Japanese patients were patch tested with various materials. At 48 h, digital photographs of the patch test areas were taken, in addition to a visual evaluation by dermatologists. Digital images of the areas were converted to erythema index (EI) images using image processing and both EI and ΔEI (the difference between the patch test site and adjacent normal skin) values of the patch test sites were compared with the corresponding visual grades. RESULTS: An excellent linear correlation (r=0.95) was found between ΔEI and visual grades, although EI also significantly correlated with visual grades. There were significant differences (P<0.0001-0.05) between the mean ΔEI values of any two adjacent visual grades. CONCLUSION: ΔEI values derived from image processing appear to be suitable for the quantitative evaluation of erythema in patch tests. This method may be helpful in overcoming the subjectiveness of visual evaluation and for training non-experts in patch testing.
Subject(s)
Dermatitis, Contact/pathology , Dermoscopy/methods , Erythema/pathology , Patch Tests/methods , Severity of Illness Index , Adult , Colorimetry/methods , Erythema/chemically induced , Female , Humans , Image Processing, Computer-Assisted/methods , Male , Middle AgedABSTRACT
BACKGROUND: Although one clinical sign of aging and/or photoaging is a yellowish discoloration of the facial skin, little is known about the cause of this change. In addition to the increase in the epidermal melanin content, it has been suggested that advanced glycation end products (AGEs), which are known to accumulate in photoaged skin, may affect this discoloration. AIM: The objective of this pilot study was to non-invasively investigate the roles of melanin and AGEs in this yellowish discoloration of the facial skin. METHODS: We examined the spectral reflectance at the cheek in 40 healthy Japanese women of various ages (mean age, 38.1 years) using a reflectance spectrophotometer and a spectrofluorimeter. The degree of yellowish tint was evaluated in terms of b(*). The amount of melanin in the skin was evaluated by calculating the melanin index (MI) A(640)-A(670) [A(lambda): log(10) (1/reflectance) at a wavelength of lambda]. The amount of AGEs was roughly evaluated using the AGEs index, which is thought to linearly correlate with the amount of intrinsic fluorescence markers irrespective of the concentration of melanin and is defined as follows: AGEs index=I(5)/SQR (I(1)xI(2)). In this equation, the intensities of reflectance are I(1) at an excitation wavelength of 335 nm, I(2) at an emission wavelength of 390 nm and I(5) at 390 nm under an excitation wavelength of 335 nm. RESULTS: Both b(*) and the AGEs index were significantly correlated with subject age (r=0.34, P<0.05 and r=0.68, P<0.0001, respectively). Significant correlations were also observed between MI and b(*) (r=0.63, P<0.0001) and between the AGEs index and b(*) (r=0.53, P<0.0005). However, no significant correlations were seen between MI and the AGEs index. CONCLUSION: The AGEs index does not appear to be influenced by the amount of melanin and may be utilized as an indicator of the amount of AGEs in the skin. AGEs are likely to play a role in the yellowish discoloration of skin with aging.
Subject(s)
Epidermis/metabolism , Melanins/metabolism , Models, Biological , Skin Aging , Spectrophotometry/methods , Adult , Biomarkers/metabolism , Color , Face , Female , Fluorescence , Glycation End Products, Advanced/metabolism , Hemoglobins/metabolism , Humans , Middle Aged , Pilot Projects , Skin Pigmentation , Young AdultABSTRACT
BACKGROUND/AIMS: The pathogenesis of dark circles of the lower eyelid (DCLE) has been considered to involve stasis and hyperpigmentation of the eyelids. We have already reported that dermal thickness of lower eyelid skin may represent another factor that affects the appearance of DCLE. The aim of this study was to evaluate the efficacy of vitamin C, which is known to increase collagen, on DCLE through a clinical trial. METHODS: Fourteen subjects with DCLE applied either 10% sodium ascorbate (ANa) or ascorbic acid glucoside (AG) lotion in split-face fashion (opposite side: vehicle only) for 6 months. Melanin index (MI), erythema index (EI), thickness and echogenicity of the dermis at bilateral lower eyelids was measured during this trial. RESULTS: Change in EI was significantly smaller on the ANa-treated side than on the vehicle-treated side. Dermal thickness tended to be thicker for the ANa-treated side than for the vehicle-treated side, although no significant difference was seen. Both EI and dermal thickness tended to change in parallel manner. On the other hand, no significant differences in changes of EI, MI, and dermal thickness were found between AG- and vehicle-treated sides. CONCLUSION: ANa may improve DCLE by thickening the eyelid dermis and concealing dark coloration due to congested blood.
Subject(s)
Ascorbic Acid/administration & dosage , Eyelid Diseases/diagnosis , Eyelid Diseases/drug therapy , Image Interpretation, Computer-Assisted/methods , Pigmentation Disorders/diagnosis , Pigmentation Disorders/drug therapy , Adult , Female , Humans , Male , Photography/methods , Treatment Outcome , Ultrasonography/methodsABSTRACT
BACKGROUND/AIMS: Dark circles of the lower eyelid (DCLE) represent a well-known beauty problem. The pathogenesis of DCLE is obscure, although stasis and hyperpigmentation of the eyelids have been considered to be involved. One reason for the small number of studies on DCLE may be the difficulty in measuring such soft and curved skin as the eyelids using bulky reflectance meters. The purpose of this study was to quantitatively analyze DCLE using various bioengineering methods. METHODS: The lower eyelid and cheek areas of 14 subjects with DCLE and 28 without DCLE were examined using two kinds of reflectance meters and image analysis to measure erythema index (EI), melanin index (MI), and oxygenation index (OX). Ultrasound echo images were also recorded to evaluate the thickness and echo density of the dermis. An in vitro model using collagen gel and hemoglobin solution was also examined as a phantom of eyelid skin. RESULTS: When contact-type reflectance meters were used, no significant differences in EI, MI, and OX were found between groups with and without DCLE. However, mean values of both MI and EI at eyelids were significantly higher in subjects with DCLE on image analysis, paralleling the results of inspection. Mean dermal thickness was significantly smaller in subjects with DCLE. CONCLUSION: Evaluation of EI and MI by image processing methods seems suitable for quantitative evaluation of DCLE, since inadequate contact of the measuring head with the skin is avoided. Whether stasis or hyperpigmentation is more responsible for DCLE remains uncertain. Dermal thickness of eyelid skin may be involved in the appearance of DCLE.
Subject(s)
Colorimetry/methods , Dermoscopy/methods , Eyelids/physiology , Image Interpretation, Computer-Assisted/methods , Photometry/methods , Skin Pigmentation/physiology , Adult , Computer Simulation , Eyelids/anatomy & histology , Humans , Models, Biological , Reproducibility of Results , Sensitivity and Specificity , Skin/anatomy & histologyABSTRACT
BACKGROUND: Quantification of erythema and pigmentation is useful for analysis of skin tests and management of skin diseases. However, reflectance instruments for this purpose suffer from many technical and financial disadvantages. The aim of this study was to establish a method for evaluation of the amounts of haemoglobin and melanin using ordinary digital cameras and Image J freeware. METHODS: Based on the theories on the absorbance of a multilayered skin model, the erythema index (EI) and melanin index (MI) images were derived by image processing from digital colour images of the skin, which were obtained with four kinds of digital cameras. The specificity of these indices and the linearity between index values and the amounts of haemoglobin and melanin were determined by using images of various concentrations of haemoglobin and melanin solutions. The accuracy of both types of index images was also examined by comparing the index values of UV-induced erythema and pigmentation of various intensities with those measured with a reflectance spectrophotometer. RESULTS: The specificity of EI and MI images was good as little interference was noted with each other. The linearity between EI and haemoglobin concentration, as well as that between MI and melanin concentration was excellent. For UV-induced erythema and pigmentation, good linear correlation was confirmed between two types of EI obtained by the two methods, as well as between two types of MI. However, the index values derived from digital images depended on the camera used as well as on the circumstantial conditions, such as the distance from objects and illumination. CONCLUSION: EI and MI images are reliable and useful for quantifying erythema and pigmentation, if obtained under constant and consistent conditions. Apart from financial benefits, this method has many advantages and greater clinical utility in comparison with reflectance instruments.
Subject(s)
Erythema/diagnosis , Hemoglobins/analysis , Image Interpretation, Computer-Assisted/methods , Melanins/analysis , Skin Pigmentation , Carcinoma, Basal Cell/pathology , Colorimetry , Erythema/etiology , Humans , Leg Ulcer/pathology , Microscopy, Video , Models, Biological , Photography/instrumentation , Photography/methods , Skin/pathology , Skin/radiation effects , Skin Neoplasms/pathology , Software , Spectrophotometry/methods , Ultraviolet RaysABSTRACT
The authors conducted a two-part study to determine whether transcutaneous oxygen pressure (TcPO (2)) and transcutaneous carbon dioxide pressure (TcPCO (2)) can be used to monitor flap viability after transplantation. The first part was an animal study in which TcPO (2) and TcPCO (2) were measured in 10 epigastric island flaps subjected to arterial or venous ischemia. The second part was a clinical study in which both were measured in 27 free skin flaps. In the experimental study, TcPO (2) decreased to nearly 0 mmHg after 10 minutes of arterial and venous ischemia. TcPCO (2) increased to 100 mmHg after 60 minutes of either type of ischemia. In the clinical study, congestion was suspected in six flaps on the basis of clinical signs alone. Three congested flaps with TcPCO (2) more than 90 mmHg were selected for intervention. The remaining three congested flaps, with TcPCO (2) 80 mmHg or less, survived completely without further treatment. The TcPO (2) of all treated flaps and of the six flaps not requiring further treatment was 0 mmHg. Results of experimental study indicate that TcPO (2) is more sensitive than TcPCO (2) to flap ischemia. However, results of clinical study suggest that it is very hard to distinguish congested flaps from healthy flaps by TcPO (2) alone. The authors believe that a congested flap with a TcPCO (2) more than 90 mmHg requires further treatment.
Subject(s)
Blood Gas Monitoring, Transcutaneous , Ischemia/blood , Surgical Flaps/physiology , Adult , Aged , Aged, 80 and over , Animals , Female , Humans , Male , Middle Aged , RabbitsABSTRACT
BACKGROUND/PURPOSE: Cutaneous hyperpigmentation occurs in multiple conditions. There is a strong need for the improvement of hyperpigmentation especially among Asian women. However, the effect of existing skin-lightening agents is not sufficient. One reason attributes to the limited capability of active agents to be delivered transepidermally. Ultrasound is one promising approach to enhance transepidermal transport. In this work, we investigate the effect of the use of high-frequency ultrasound together with coupling gel containing skin-lightening agents (ascorbyl glucoside and niacinamide) on facial hyperpigmentation in vivo in Japanese women. METHODS: The effect of ultrasound on the absorption of skin-lightening agents into the stratum corneum was evaluated in a tape-stripping method on human forearms in vivo. The skin efficacy was assessed in a facial clinical trial involving 60 subjects with hyperpigmentation in a paired design. Subjects were assigned to two groups, each group using two treatments (one on each facial cheek): (1) skin-lightening gel with ultrasound vs. no treatment or (2) skin-lightening gel with ultrasound vs. skin-lightening gel treatment. Changes in facial hyperpigmentation were objectively quantified by computer analysis and visual grading of high-resolution digital images of the face in addition to the subjective assessment via questionnaire. RESULTS: Ultrasound radiation enhanced the absorption of skin-lightening agents in the stratum corneum in a radiation-time-dependent manner. In the facial clinical trial, use of ultrasound radiation together with the skin-lightening gel significantly reduced facial hyperpigmented spots compared with both no treatment and skin-lightening gel alone after 4 weeks. CONCLUSIONS: The data suggest that use of high-frequency ultrasound radiation together with skin-lightening gel is effective to reduce hyperpigmentation via enhancing transepidermal transport of skin-lightening agents.
Subject(s)
Ascorbic Acid/administration & dosage , Hyperpigmentation/therapy , Niacinamide/administration & dosage , Skin Pigmentation/drug effects , Skin Pigmentation/radiation effects , Ultrasonic Therapy/methods , Adult , Combined Modality Therapy , Dermatologic Agents/administration & dosage , Female , Humans , Middle Aged , Treatment OutcomeABSTRACT
Thioridazine is a phenothiazine derivative that has been used as an antipsychotic; it rarely causes photosensitization. However, we noticed that this drug induced an erythematous reaction in a photopatch test. Six volunteers were patch tested with various concentrations of thioridazine and irradiated with a range of UVA doses, and the time courses of the color of and blood flow to the test sites were monitored. The free-radical metabolites of thioridazine generated under UVA irradiation and its effects on ascorbate radical formation were examined with an electron paramagnetic resonance (EPR) spectrometer in vitro. As a result, immediate erythema developed during UVA irradiation in most subjects when 1% thioridazine was applied for 48 h and irradiation doses were higher than 4 J cm(-2). Another peak of erythematous reaction was observed 8-12 h after irradiation. The in vitro examination detected an apparent EPR signal, which appeared when 2 mM thioridazine in air-saturated phosphate buffer was irradiated with UVA, whereas this reaction was attenuated under anaerobic conditions. The EPR signal of the ascorbate radical was augmented under both aerobic and anaerobic conditions. Thioridazine-derived oxidants and/or thioridazine radicals generated during UVA irradiation seem to play an important role in this unique phototoxic reaction.
Subject(s)
Dermatitis, Photoallergic/pathology , Erythema/chemically induced , Thioridazine/adverse effects , Ultraviolet Rays , Adult , Ascorbic Acid/metabolism , Dermatitis, Photoallergic/diagnosis , Dermatitis, Phototoxic/diagnosis , Dermatitis, Phototoxic/pathology , Dose-Response Relationship, Drug , Dose-Response Relationship, Radiation , Electron Spin Resonance Spectroscopy , Erythema/drug therapy , Free Radicals/metabolism , Humans , Male , Middle Aged , Patch Tests/methods , Thioridazine/metabolism , Time FactorsABSTRACT
Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder characterized by oculocutaneous albinism (OCA), bleeding tendency, and lysosomal accumulation of ceroid-like material. Seven genetically distinct subtypes of HPS are known in humans; most are rare outside of Puerto Rico. Here, we describe the analysis of the HPS1 gene in 24 Japanese OCA patients who lacked mutations in the four genes known to cause OCA (TYR/OCA1, P/OCA2, TYRP1/OCA3, and MATP/OCA4), and the identification of eight different HPS1 mutations in ten of these patients, four of which were novel (W583X, L668P, 532insC, 1691delA). An IVS5+5G --> A splice consensus mutation was particularly frequent, the result of a founder effect for this allele in Japanese patients. Functional analysis by transfection of the L668P variant into Hps1-mutant melan-ep mouse melanocytes showed that this missense substitution is pathologic, resulting in an Hps-1 protein that is unable to assemble into the biogenesis of lysosome-related organelles complex-3.
Subject(s)
Albinism/genetics , Hermanski-Pudlak Syndrome/genetics , Membrane Proteins/genetics , Mutation , Animals , Female , Guanine Nucleotide Exchange Factors , Haplotypes , Humans , Male , Melanocytes/chemistry , Membrane Proteins/physiology , Mice , Phenotype , Proteins/geneticsABSTRACT
Skin pigmentation results in part from the transfer of melanized melanosomes synthesized by melanocytes to neighboring keratinocytes. Plasma membrane lectins and their glycoconjugates expressed by these epidermal cells are critical molecules involved in this transfer process. In addition, the derivative of vitamin B(3), niacinamide, can inhibit melanosome transfer and induce skin lightening. We investigated the effects of these molecules on the viability of melanocytes and keratinocytes and on the reversibility of melanosome-transfer inhibition induced by these agents using an in vitro melanocyte-keratinocyte coculture model system. While lectins and neoglycoproteins could induce apoptosis in a dose-dependent manner to melanocytes or keratinocytes in monoculture, similar dosages of the lectins, as opposed to neoglycoproteins, did not induce apoptosis to either cell type when treated in coculture. The dosages of lectins and niacinamide not affecting cell viability produced an inhibitory effect on melanosome transfer, when used either alone or together in cocultures of melanocytes-keratinocytes. Cocultures treated with lectins or niacinamide resumed normal melanosome transfer in 3 days after removal of the inhibitor, while cocultures treated with a combination of lectins and niacinamide demonstrated a lag in this recovery. Subsequently, we assessed the effect of niacinamide on facial hyperpigmented spots using a vehicle-controlled, split-faced design human clinical trial. Topical application of niacinamide resulted in a dose-dependent and reversible reduction in hyperpigmented lesions. These results suggest that lectins and niacinamide at concentrations that do not affect cell viability are reversible inhibitors of melanosome transfer.
Subject(s)
Keratinocytes/drug effects , Keratinocytes/metabolism , Lectins/pharmacology , Melanosomes/drug effects , Melanosomes/metabolism , Niacinamide/pharmacology , Administration, Topical , Adult , Cell Survival/drug effects , Cells, Cultured , Coculture Techniques , Double-Blind Method , Female , Humans , Hyperpigmentation/drug therapy , Hyperpigmentation/metabolism , Hyperpigmentation/pathology , Keratinocytes/cytology , Melanocytes/cytology , Melanocytes/drug effects , Melanocytes/metabolism , Middle Aged , Niacinamide/administration & dosage , Niacinamide/therapeutic use , Skin Pigmentation/drug effects , Skin Pigmentation/physiologyABSTRACT
BACKGROUND: The standard method used to determine the potency of antihistaminesis to assess the degree of suppression of skin response to histamine challenge. OBJECTIVES: The aims of this study were to compare the efficacy of 3 antihistaminesusing a histamine challenge test and the usefulness of on-site evaluation with that of photographic evaluation of skin-test reactions. METHODS: In this prospective, double-blind, crossover study, healthy volunteerswere given cetirizine 5 mg (CTZ-5) and 10 mg (CTZ-10), loratadine 10 mg (LOR), fexofenadine 60 mg BID (FEX), and placebo (PLC), in a randomly assigned order, with an interval of at least 1 week between treatments. Before and 0.5 to 24 hours after administration, the areas of flare and wheal induced by histamine iontophoresis were measured directly (on site) by 1 evaluator and by another evaluator using photographic images on a computer monitor. RESULTS: Ten healthy volunteers (6 men, 4 women; mean age, 28.2 years[range, 20-39 years]; mean weight, 60.7 kg [range, 41-81 kg]) were enrolled. The data from 9 subjects were analyzed; the data from 1 subject were omitted because the subject used an over-the-counter cold medication containing diphenhydramine several times during the study. By both methods, all antihistamines were shown to suppress flare significantly from 4 to 24 hours after administration. CTZ was most potent in suppressing both flare and wheal. For flare, the areas as measured using on-site evaluation were larger overall than those measured using photographic evaluation, but the shapes of the time-course graphs were similar for both. Overall, the flare area measurements started to decrease significantly from baseline values 4 hours after drug administration, reached a nadir at 10.5 hours, and remained significantly lower compared with baseline values at 24 hours. Comparisons between antihistamines showed significant differences in mean flare areas between the 2 doses of CTZ and LOR from 8 to 12 hours after administration in both evaluation methods. The wheal areas were significantly reduced from baseline values by most of the antihistamines 4 to 12 hours after drug administration, reached their lowest values at 10.5 hours, and returned to near-baseline values at 24 hours. Comparisons with PLC values at each time point, however, showed significant differences only for CTZ-5 and CTZ-10 from 4 to 12 hours after administration. Comparison between antihistamines showed significant differences in mean flare areas between the 2 doses of CTZ and LOR from 8 to 12 hours after administration in both evaluation methods. Although the flare areas measured by both methods correlated linearly (r = 0.90; P < 0.001), the correlation for wheal areas was weaker (r = 0.76; P < 0.001). CONCLUSIONS: In this study in healthy volunteers, single doses of CTZ 5 mg and CTZ 10 mg were more potent compared with single-dose LOR 10 mg and FEX 60 mg BID in suppressing skin response. Although linear correlations were found between skin-response areas, as measured by on-site and photographic evaluation, it was difficult to differentiate between wheal and flare by photographic evaluation, especially when a typical wheal was suppressed to slightly edematous erythema by antihistamines.
ABSTRACT
BACKGROUND/AIMS: Although reflectance spectrophotometry is often applied to measurement of skin color, raw data of reflectance spectra of normal and lesional skin are difficult to analyze. The purpose of this pilot study was to determine whether measurement of spectral difference in absorbance (SDA) between various skin lesions and normal skin adjacent to them could yield useful information for clinics in dermatology. METHODS: We studied spectral reflectance of a total of 173 various skin lesions. After converting obtained reflectance into apparent absorbance A (=log(10)(1/reflectance)), we examined the profile of SDA, that is, A(lesion)-A(normal skin) in the range of 400-700 nm, and compared them with the absorbance spectra of melanin and hemoglobin. RESULTS: SDA of epidermal pigmentary disorders was similar to the absorption spectrum of melanin in vitro, but the cases with intradermal melanin deposition showed a different pattern, reflecting the scattering effect of the dermis. SDA of erythematous lesions was similar to the spectra of either oxygenated or reduced hemoglobin, and varied according to the oxygenated level of cutaneous blood. SDA of lesions with a combination of factors appeared as a simple summation of spectra corresponding to each of the factors. CONCLUSIONS: Our method may offer easy and quick detection of major pathophysiological changes in skin lesions.
Subject(s)
Hemoglobins/analysis , Melanins/analysis , Skin Diseases/diagnosis , Spectrophotometry/methods , HumansABSTRACT
BACKGROUND: Various skin lesions occur in association with rheumatoid arthritis (RA). OBSERVATION: We report a distinctive skin lesion observed in 4 patients with RA. All patients had RA for many years and developed asymptomatic, irregularly shaped erythema over the swollen elbow joints and the nearby part of the forearm. Histopathologically, all cases showed massive aggregates mainly composed of histiocytes in markedly dilated vessels in the dermis, accompanied by a dermal infiltrate of lymphocytes, plasma cells, neutrophils, or a combination of these. A total of 9 cases, including ours, showing similar histopathologic findings have been reported in the literature, of which 7 were associated with RA and presented relatively common clinical appearance. CONCLUSION: In spite of some disagreement as to whether the dilated vessels are blood vessels or lymphatics, it is most likely that these 7 cases belong to the same clinical entity closely associated with RA.
Subject(s)
Arthritis, Rheumatoid/complications , Histiocytosis/complications , Skin Diseases, Vascular/complications , Aged , Blood Vessels/pathology , Female , Histiocytes/pathology , Histiocytosis/metabolism , Histiocytosis/pathology , Humans , Immunohistochemistry , Lymphatic System/pathology , Male , Middle Aged , Skin/blood supply , Skin/chemistry , Skin/pathology , Skin Diseases, Vascular/metabolism , Skin Diseases, Vascular/pathologyABSTRACT
BACKGROUND/AIMS: There are few available methods that can be used to quantify hyperpigmented spots on a wide area of the face. The objective of this study was to develop such a method through the use of specialized image analysis technologies. METHODS: This imaging system was composed of a source of illumination whose light intensity was controlled with a dimmer, a 3-CCD video camera connected to a computer, and a positioning device used to correctly align the subject's face. This system was calibrated by adjusting the light intensity, the camera position, and white balance of the camera in order to acquire reproducible images. Using a specific algorithm for the image analysis, this system enabled us to measure both the total area of hyperpigmented spots (mm2) and the averaged skin colour tone (quasi L*a*b*) excluding the area of those hyperpigmented spots in a wide area of the face. The accuracy and reproducibility of the system was validated using a mannequin head with six standard colour chips obtained from the GretagMacbeth ColorChecker, and brown-coloured patches that simulated hyperpigmented spots whose colour and area were both known. The correlation between CIE L*a*b* and quasi L*a*b* values was examined by conducting simultaneous measurements of the facial skin colour of 187 subjects with a tristimulus colourimeter (Minolta Chromameter) and our imaging system. RESULTS: The measurement errors in quasi L*a*b* values of colour chips and the area of brown patches were less than 2 and 5%, respectively, unless these chips or patches were located in the peripheral zone of the mannequin head. The variation in quasi L*a*b* values and the area of hyperpigmented spots (mm2) in five repeated measurements performed once every hour was less than 2%. There was an excellent correlation between the CIE L*a*b* and quasi L*a*b* values, and the Pearson's correlation coefficient between CIE L* and quasi L* value, for instance, was 0.908. CONCLUSIONS: : As long as the region to be evaluated is limited to the cheek and periorbital areas, this system enables automatic detection of hyperpigmented spots in a wide area of the face, as well as the correct measurement of those areas and determination of skin colours.
Subject(s)
Diagnosis, Computer-Assisted , Facial Dermatoses/pathology , Pigmentation Disorders/pathology , Adult , Cheek , Female , Forehead , Humans , Mandible , Models, Theoretical , Orbit , Skin PigmentationABSTRACT
BACKGROUND/AIMS: The aim of this study was to quantify and confirm the efficacy of cosmetic formulations for hyperpigmented spots over a wide area of the face using a high quality digital imaging system that we developed. METHODS: A total of 120 Japanese female volunteers aged 25-60 years with solar lentigines were treated for 6 months with a skin lightening moisturizer (SLM, thereafter) containing 3% magnesium ascorbyl phosphate on one side of the face and vehicle on the other side. During the course of the study, facial images were collected by the image analysis to measure facial skin colour and the total area of hyperpigmented spots. The evaluation was also conducted by visual grading. Measurements were made before and 1, 3, and 6 months after starting the application, and again 6 months after discontinuing the treatment. Three similar clinical studies using the same protocol were repeated for up to one-month to confirm the reproducibility of the results and to examine seasonal variation. RESULTS: SLM significantly reduced the total area of hyperpigmented spots (P < 0.005) after one month of treatment compared to the vehicle, with no significant variation in facial skin colour tone in the areas outside the hyperpigmented spots. The results of the visual grading were consistent with those obtained by image analysis. The total area of hyperpigmented spots 6 months after discontinuing the treatment had returned to pre-treatment levels. The reproducibility of these clinical results was demonstrated in three follow-up studies. CONCLUSIONS: A high-resolution digital imaging method, combined with a split-face clinical protocol is sensitive enough to prove that SLM readily reduces hyperpigmented spots, while maintaining normal facial skin colour.