A uniformly diffusing applicator can be advantageous for laser treatment of tubular tissue. The current study investigated various conical angles for diffuser tips as a critical factor for achieving radially uniform light emission. A customized goniometer was employed to characterize the spatial uniformity of the light propagation. An ex vivo model was developed to quantitatively compare the temperature development and irreversible tissue coagulation. The 10-mm diffuser tip with angle at 25° achieved a uniform longitudinal intensity profile (i.e., 0.90 ± 0.07) as well as a consistent thermal denaturation on the tissue. The proposed conical angle can be instrumental in determining the uniformity of light distribution for the photothermal treatment of tubular tissue.

The aim of the current study is to investigate the effect of radial and cylindrical light distributions on the response of vascular tissue during 1470-nm irradiation in ex vivo models. Due to a low irradiance (5.3 W/cm²) and wide light distribution, cylindrically diffusing irradiation yielded uniform thermal coagulation while radial irradiation accompanied delamination of layers in leporine veins. Bovine foot model testing verified that the diffusing irradiation was associated with the steady maximum temperature and no tissue attachment, compared with the radial irradiation. The proposed cylindrical light application can be a feasible way to treat varicose veins in an effective manner.

Stress urinary incontinence (SUI) is a prominent incontinence caused by increased abdominal pressure. Sling treatments are surgical procedures used to treat SUI by inserting an artificial mesh into the urethra. However, after the sling treatments, patients can be at risk of chronic pain and infection in the urological system. The current research aims to develop new non-ablative transurethral laser treatment for SUI as a minimally invasive and non-implantable procedure. Six females porcine were randomly divided into three groups: Control, day 0 and day 28 after laser treatment. The urethra was dilated using a balloon-assisted diffusing applicator and irradiated with a 980-nm laser light at 20 W for 15 s. To compare the efficacy of the treatment, urethral tissues were harvested on days 0 and 28 for histological evaluation. 28 days after the laser treatment, the urethra thickness was 46% greater than the control group, indicating an increase in collagen deposition in the urethra. The transurethral laser treatment groups exhibited significantly higher levels of collagen reconstruction-related proteins (VEGF and collagen type 3), compared to the control group, without causing thermal damage to the urethral mucosa. The current findings demonstrated the feasibility of the non-ablative transurethral laser treatment for SUI without thermal damage to the urethral mucosa. Further investigations will be pursued to validate functional and molecular changes of the laser-treated urethra in a disease-induced animal model in order to warrant the efficacy and safety of the transurethral laser treatment for clinical translations.

The current study aims to evaluate the efficacy and safety of photothermal duodenal mucosal ablation (PDMA), utilizing a 1470 nm wavelength and a diffusing fiber (DF), in ex vivo liver tissues and an in vivo type 2 diabetes mellitus (T2DM) rat model. The 1470 nm laser with the DF was used for uniform duodenal mucosal ablation. After optimizing dosimetry (9–49 J) ex vivo, PDMA was performed on twelve T2DM rats (n = 4 per group) induced by a high-fat diet and streptozotocin. Glycemic metabolism and histological changes were monitored for 14 days. All experimental data were analyzed using the Mann–Whitney U test for statistical significance. Optimized PDMA (5 W for 5 s) achieved uniform, circumferential mucosal ablation while preserving outer layers. Histology assessment confirmed optimal ablation at day 2 with substantial regeneration by day 14. Consequently, the PDMA group showed significantly improved glycemic indexes at day 14 compared to the sham control. Therefore, the proposed PDMA may be promising in remodeling the duodenal mucosa for glycemic control in T2DM. Future research will evaluate the PDMA in a larger number of animals to warrant efficacy and safety for clinical translation.

Gastroesophageal reflux disease (GERD) is a prevalent disorder caused by lower esophageal sphincter (LES) dysfunction, often requiring long-term treatment. This study assessed the feasibility of endoscopic balloon-assisted laser treatment (EBLT) using a porcine GERD model. One week after GERD induction, EBLT was performed on three animals, while one served as a control. A 980 nm continuous-wave laser was delivered at 30 W for 90 s (energy = 2700 J and power density = 2.17 W/cm²) in a circumferential, non-contact manner using a balloon-assisted catheter. Real-time mucosal temperature monitoring was achieved using a fiber Bragg grating (FBG) sensor integrated with the balloon, maintaining temperatures below 40 °C. Endoscopic ultrasound and manometry were used to evaluate LES thickness and pressure before and after treatment. After a 12-week observation period, esophageal tissues were harvested for histological and gene expression analysis. Compared to the control, the treated group showed an increase in LES thickness (3.6 ± 0.2 mm vs. 1.5 mm) and relative LES pressure changes (2.9 ± 1.6 vs. 0.6). Upregulation of fibrosis- and hypertrophy-related genes suggested structural remodeling of the LES. No adverse effects or mucosal injury were observed. These findings support EBLT as a promising and minimally invasive strategy for GERD treatment.