๐ ็ธฝ็ฎ้ ๏ฝ ๐ ่ฑๆๅๆ๏ผๆฌ็ฏ๏ผ ๏ฝ ๐ ๅฎๆด็ฟป่ญฏ ๏ฝ โญ ็ฒพ่ฏ็ญ่จ
Intense pulsed light
Intense pulsed light
The use of intense pulsed light (IPL) was first described in 1976 by Muhlbauer et al. for the treatment of telangiectasias.48 It has since been shown to be effective in treating a variety of dyspigmentation disorders. Examples of its use include the treatment of melasma, acne vulgaris, rosacea, solar lentigines, and actinic keratosis.49 It works by emitting a noncoherent, polychromatic light via a filtered flashlamp.50 The light is placed at a set wavelength spectrum (500โ1,300 nm) and pulse duration. Firstgeneration IPL devices emit infrared light which commonly led to epithelial damage. Second-generation IPL devices filter out the infrared portion of the light, thus reducing the risk of SE.51 The mechanism of action of IPL involves absorption of light energy by melanin in keratinocytes and melanocytes. This is followed by the formation of microcrusts in these sites of epidermal injury with subsequent shedding off of the crusts leading to improvement of pigmentation.49 A recent study demonstrated the effectiveness of IPL therapy in the treatment of melasma in Chinese patients. Results showed 77.5% of participants obtained 51% to 100% improvement with the mean melasma area and severity index scores decreasing from 15.2 to 4.5.52
Q-switched neodymium-doped yttrium aluminum garnet (QS Nd:YAG) laser
QS Nd:YAG lasers are used to treat dyspigmentation due to their low potential for scarring. One of its advantages is its ability to penetrate deeply through the skin (up to 1 cm) in order to target melanosomes present in melanocytes, keratinocytes, and phagocytes. It works by inducing selective photothermolysis of melanosomes. This is accomplished through producing large temperature gradients between the melanosome and its surrounding structures causing fragmentation of the melanosome. In addition high-pressure acoustic waves produced by the laser lead to melanocyte death.53 One study followed 50 patients receiving weekly QS Nd:YAG laser treatment for melasma over a 9-week period. Results showed a decrease in mean melanin index by 35.8%. However, the recurrence rate at 3 months was 64%.54 Significant SE from recurrent QS Nd:YAG laser therapy include hypopigmentation, rebound hyperpigmentation, and melasma recurrence.53