Peter Alshede Philipsen

Phototherapy using ultraviolet radiation (UVR) treatment units of various designs is common in dermatology. The anatomical distribution of UVR should be even, regardless of individual body shapes. Using electronic dosimeters, we measured the irradiance at 31 body sites on 12 persons of different heights and body mass (BMI). Five different treatment unit designs were tested: cabinet units with standing patients, units with patients lying down, and a unit where patients rotated in front of flatly arranged UVR tubes. In treatment units with short tubes, persons taller than 170 cm received low irradiance on the face, neck, and shoulders. In cabinet-type units, higher BMI lowered the irradiance on the chest and belly. The relative standard deviation (RSD) of irradiance was smallest for the rotating unit, and for the unit with patients lying down while irradiated from above only. A higher RSD was found in the unit designs where patients stood inside cabinets, and where patients lay down and were simultaneously irradiated from both sides. In general, longer tubes lower the overall RSD. The irradiance of the different body areas is about 60% of the measured calibration values, but to avoid provoking any erythema, the treatment dose can only be increased by 10%.

Purpose Conventional oral antifungal therapies for onychomycosis (OM) often do not achieve complete cure and may be associated with adverse effects, medical interactions, and compliance issues restricting their use in a large group of patients. Topical treatment can bypass the systemic side effects but is limited by the physical barrier of the nail plate. Ablative fractional laser (AFL) treatment can be used to improve the penetration of topical drugs into the nail. This study visualized the effects of laser ablation of nail tissue and assessed their impact on the biodistribution of a fluorescent dye in healthy and fungal nail tissue. Methods For the qualitative assessment of CO 2 AFL effects on healthy nail tissue, scanning electron microscopy (SEM), coherent anti‐Stokes Raman scattering microscopy (CARS‐M), and widefield fluorescence microscopy (WFM) were used. To quantitate the effect of laser‐pretreatment on the delivery of a fluorescent dye, ATTO‐647N, into healthy and fungal nail tissue, ablation depth, nail plate thickness, and ATTO‐647N fluorescence intensity in three nail plate layers were measured using WFM. A total of 30 nail clippings (healthy n = 18, fungal n = 12) were collected. An aqueous ATTO‐647N solution was directly applied to the dorsal surface of 24 nail samples (healthy n = 12, fungal n = 12) and incubated for 4 hours, of which half (healthy n = 6, fungal n = 6) had been pretreated with AFL (30 mJ/mb, 15% density, 300 Hz, pulse duration <1 ms). Results Imaging revealed a three‐layered nail structure, an AFL‐induced porous ablation crater, and changes in autofluorescence. While intact fungal samples showed a 106% higher ATTO‐647N signal intensity than healthy controls, microporation led to a significantly increased fluorophore permeation in all samples ( p < 0.0001). AFL processing of nail tissue enhanced topical delivery of ATTO‐647N in all layers, (average increase: healthy +108%, fungal +33%), most pronounced in the top nail layer (healthy +122%, fungal +68%). While proportionally deeper ablation craters correlated moderately with higher fluorescence intensities in healthy nail tissue, fungal samples showed no significant relationship. Conclusion Fractional CO 2 laser microporation is a simple way of enhancing the passive delivery of topically applied ATTO‐647N. Although the impaired nail plate barrier in OM leads to greater diffusion of the aqueous solution, AFL can increase the permeability of both structurally deficient and intact nails.