Usefulness of a Narrow-Band Reflectance Spectrophotometer in Evaluating Effects of Depigmenting Treatment

Abstract

Abstract. As a depigmenting treatment, combined topical applications of all-trans retinoic acid (atRA) aqueous gel and 5% hydroquinone, 7% lactic acid ointment were used for Oriental patients with hyperpigmented skin lesions such as senile lentigines and nevus spilus. A narrow-band reflectance spectrophotometer and a tristimulus colorimeter were used to evaluate objectively the intensity of pigmentation and erythema at each clinical visit. L*, a*, and b* values measured with a tristimulus colorimeter (Chroma Meter CR-300) enabled the evaluation of erythema but not pigmentation. On the other hand, the melanin and hemoglobin values measured with a narrow-band reflectance spectrophotometer (Mexameter MX-16) expressed both erythema and pigmentation well. It was revealed that, in our bleaching protocol, the narrow-band reflectance spectrophotometer was quite useful for estimating accurately the intensity of pigmentation and erythema and determining the best time point for the cessation of atRA treatment. Key words: Depigmenting treatment-Retinoic acid aqueous gel-Senile lentigines-Nevus spilusUsing our bleaching protocol with a high concentration of all-trans retinoic acid (atRA) aqueous gel in combination with hydroquinone and lactic acid, a remarkable improvement of various skin lesions with hyperpigmentation, such as senile lentigines [13], melasma, postinflammatory hyperpigmentation, and nevus spilus, was obtained with a short period of treatment [14]. However, during the treatment, side effects such as erythema were frequently observed after the topical application of atRA.Tristimulus colorimeters and full-range or narrowband spectrophotometers have been employed for the quantification of erythema and pigmentation induced by ultraviolet radiation (UVR) [7], and for the color analysis of skin lesions [9] or transferred skin [12]. We have used a tristimulus colorimeter and a narrow-band spectrophotometer to evaluate skin reactions such as the intensity of pigmentation and erythema in our bleaching treatment. Representative cases are demonstrated and the usefulness of the reflectance spectrophotometer is discussed. MethodsCombined topical applications of atRA, hydroquinone, and lactic acid were used for skin lesions with hyperpigmentation. atRA aqueous gel (atRA gel; 0.1, 0.2, and 0.4%) was originally prepared at the Department of Pharmacy, University of Tokyo. AtRA gel was topically applied together with 5% hydroquinone, 7% lactic acid ointment (HQ-LA ointment), also prepared as described above. Plastibase (petrolatum polyethylene ointment base; Taisho Pharmacology, Osaka, Japan) was used as the ointment base of HQ-LA ointment. Both atRA gel and HQ-LA ointments are pharmacologically unstable, so that fresh ointments were prepared at least once a month. Each ointment was topically applied under signed informed consent to more than 120 Oriental patients with hyperpigmented skin lesions such as sinile lentigines, melasma, postinflammatory hyperpigmentation, and nevus spilus.Treatment protocol. atRA gel was applied to...

Assessment of Topical Hypopigmenting Agents on Solar Lentigines of Asian Women

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Reflectance spectroscopy for noninvasive evaluation of hair follicle stage

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Vitiligo Coexistent with Nevus Depigmentosus: This Was Treated with Narrow-Band UVB and These Lesions Were Followed Using the Mexameter®, a Pigment-Measuring Device

“…Although these devices are often used for cosmetics research, they have only rarely been applied in clinical practice 3,4 . In this study, we used the Mexameter Ⓡ , a narrow-band reflectance spectrophotometer, to measure the intensity of the erythema and melanin pigmentation.…”