Photodynamic Therapy

Photodynamic therapy (PDT) is a well-established, non-invasive treatment that has shown desirable effects such as improvement of fine lines, dyspigmentation, and other signs of photodamage. Many people seek to decrease, or reverse, effects of sun damage on the skin. Hyaluronic acid (HA), a naturally occurring glycosaminoglycan found in the body, has enormous potential to bind water which allows the skin to retain moisture and maintain elasticity. Topical application of HA has been found to produce anti-wrinkle effects.

Intrinsic aging of the skin is associated with decreased proliferative activity of skin cells including keratinocytes, melanocytes, and fibroblasts. Exposure to light, specifically ultraviolet A (UVA), for extended periods of time, causes extrinsic atrophy of the skin, leading to photodamage and premature aging of the skin. Features of photodamaged skin include wrinkles, discoloration, erythema and sebaceous gland hypertrophy.

Previous studies using PDT for treatment of photodamaged skin have found significant histological and clinical improvements including increased collagen, smoother skin texture, and fewer wrinkles. Moreover, hypertrophic scarring has been found to improve with less erythema, reduced volume, and increased flexibility.

Many seek to decrease, or reverse, effects of sun damage on the skin. According to the Annual Statistics Report by the American Society of Plastic Surgeons, 15.9 million minimally invasive cosmetic procedures were performed in 2018, resulting in a total expenditure of 8.8 billion dollars. According to the American Society for Dermatologic Surgery (ASDS), 3.27 million procedures using laser, light, and energy-based devices were performed in 2017, making those procedures the most popular cosmetic treatment. In addition, a survey done by ASDS in 2018 revealed that treatments to tighten the skin or smooth wrinkles using ultrasound, laser, light, or radiofrequency were the most common procedures that consumers opted to undergo.

According to blinded reviewers, clinically visible improvement was apparent with most patients from baseline compared with 3-month photos. It is believed that hyaluronic acid delivery via PDT allows for a non-invasive therapy that is more affordable and more accessible to the general population than currently available methods such as lasers or injectables.

Digital analysis of photographs by imaging systems demonstrated improvement of skin spots, wrinkles, pores, texture, UV spots, brown spots, red areas, and porphyrins. Wrinkles, pores, and redness parameters approached significance, showing a positive trend. Although not statistically significant, results were clinically significant and relevant as patients and dermatologists noticed an improvement in overall skin appearance. Patients also reported improvement of skin texture, pigmentation, and pores after treatment.

Findings are consistent with previous reports. Lowe et al. used 5% ALA (5-aminolevulinic acid - widely used in medicine for photodynamic diagnosis (PDD) and therapy) for 30 min and subsequent LED-RL for one session. There was minimal phototoxic response with a reduction of fine lines in 67% of patients and increased skin softness in all patients. Another study using 5% ALA for 2 h and then LED-RL exposure found improvement of photoaged lesions, stratum corneum hydration, elasticity, trans-epidermal water loss, and melanin index. These improvements were more obvious than an intense pulsed laser-only group.

This pilot case series was limited by the small sample size and emphasises the need for larger studies due to the positive trends of data. The participants were younger than the typical age included in photo-rejuvenation studies and the range of skin types was limited. Efforts were made to decrease bias by utilising randomisation of grading and digital analysis.

A study with larger sample size, longer sessions, additional sessions, or longer follow-up period may be necessary to detect statistically significant differences in skin quality parameters. While PDT is often used in older adults for the treatment of actinic keratosis, it is unclear whether PDT at a younger age has benefits in preventing actinic keratosis formation. PDT treatment with ALA-HA in younger patients may provide a non-invasive alternative for “prejuvenation”.

The ASDS has found that there is an increasing interest in the under-30 age group in preventative skincare treatments as the use of fillers and neuromodulators has surged in the past few years. Future studies with larger patient populations and longer follow-up are necessary.

Alternative light sources such as daylight or LED blue light may also be studied to determine protocols for maximal improvement.

Not my own work! Taken from:

Huang, A., Nguyen, J.K., Austin, E. et al. Facial rejuvenation using photodynamic therapy with a novel preparation of ALA and hyaluronic acid in young adults. Arch Dermatol Res 312, 567–573 (2020). https://doi.org/10.1007/s00403-020-02038-5

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