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Updated: Oct 14, 2025
An In Vitro Approach to Photodynamic Therapy
Published on: August 17, 2018
Clinical evaluation of a short illumination duration (1 hour) when performing photodynamic therapy of actinic
Background:
Photodynamic therapy (PDT) using daylight as the photoactivating light source (DL-PDT) is an effective treatment for actinic keratosis (AK). Among the artificial daylight sources, the Dermaris (Surgiris, Croix, France) is specially designed for SDL-PDT (simulated daylight PDT) of AK. To perform the PDT session, a long duration (2.5 h) and low-intensity light exposure (2.9 mw/cm²) is used. This long duration is considered as a major limitation by both the patient and the dermatologist.
Objectives:
The paper aims to report the clinical outcomes of SDL-PDT using the Dermaris in patients treated for AK lesions of the scalp at our medical dermatology center using only one hour low-intensity light exposure.
Methods:
Thirty patients (19 males, 11 females), mean age: 72.8 ± 9.3, with phototype 1 (11 patients), with phototype 2(17 patients) and phototype 3 (2 patients), with grade I-II AK of the scalp were treated with a drug-light interval (DLI) of 10 min and a light exposure of 1 h. The cure rate of AK lesions at six months after the treatment was determined. Erythema, crusts, discomfort and during or/and post the treatment were also evaluated.
Results:
In total, 293 AK were treated. Six months following treatment, the cure rate of patients was 93%. Pain score reported after the first PDT session was from 0 to 1 on a visual analogue scale (VAS) ranging from 0 to 10. Erythema was observed in 28 patients and lasted 3 days, crusts were seen in 19 patients. Discomfort was as mild or less in more than 97% of patients.
Conclusions:
the shortening of the exposure time to one hour does not modify the efficacy of the SDL-PDT using the Dermaris. This observation is in agreement with recent published data demonstrating that PDT can be performed successfully with half the illumination time used in daylight PDT today. Besides, this clinical study confirmed that SDL-PDT is an effective and nearly painless treatment with minimal side effects for patients with AK lesions of the scalp.
