๐ ็ธฝ็ฎ้ ๏ฝ ๐ ่ฑๆๅๆ๏ผๆฌ็ฏ๏ผ ๏ฝ ๐ ๅฎๆด็ฟป่ญฏ ๏ฝ โญ ็ฒพ่ฏ็ญ่จ
Photodynamic therapy
Photodynamic therapy
PDT uses a photosensitizing agent, such as ALA, methyl aminolevulinate (MAL), or indole-3-acetic acid (IAA). These photosensitizing agents become absorbed by the pilosebaceous unit and augment its response to a light source. The use of photosensitizing agents results in the production of free radicals in the epithelium and pilosebaceous unit, leading to P. acnes destruction. Light sources commonly used in PDT include diode lasers, near-infrared diode lasers, and other lasers with outputs in the visible light range, such as IPL, LEDs, blue light, and red light.42 One study showed that P. acnes cultures grown in the presence of ALA led to a fivefold decrease in culture viability after three illuminations of high-intensity blue light.43 Furthermore, treatment of inflammatory lesions with PDT may increase acne clearance by 42% compared to IPL alone at 12-week follow-up.44 Several other split-face trials have also reported a higher reduction in lesions when treated with PDT than when treated with light therapy alone. The use of ALA, in conjunction with IPL and MAL, in conjunction with PDL, have been examined, with studies showing greater improvements when the photosensitizing agent is used in combination with the light source. In addition to red light, blue light has also demonstrated efficacy when used in combination with ALA.44,45 As a lipophilic derivative of ALA, MAL has better penetration properties. Two studies evaluating the efficacy of MAL found modest improvements.46,47
The use of ALA and red light may result in a transient acne-like folliculitis and reduced sebum secretion after 20 weeks of PDT therapy.42 ALA and red light ultimately led to statistically significant clearance rates for inflammatory acne. Despite its efficacy as a treatment, major side effects were observed, including phototoxicity to the sebaceous follicles and prolonged inhibition of sebaceous gland activity. PDT sessions in 23 patients were accompanied by acute erythema, edema, and an acute acneiform eruption, with occasional side effects consisting of vesicle formation, purpura, and hyperpigmentation.42 PDT is not generally considered a first-line treatment for acne, though it may be useful for severe nodulocystic acne recalcitrant to other treatments as an alternative to isotretinoin.42