Semi-Automated method of analysis of horizontal histological sections of skin for objective evaluation of fractional devices.

BACKGROUND AND OBJECTIVE: The treatment of skin with fractional devices creates columns of micro-ablation or micro-denaturation depending on the device. Since the geometric profiles of thermal damage depend on the treatment parameters or physical properties of the treated tissue, the size of these columns may vary from a few microns to a few millimeters. For objective evaluation of the damage profiles generated by fractional devices, this report describes an innovative and efficient method of processing and evaluating horizontal sections of skin using a novel software program. MATERIALS AND METHODS: Ex vivo porcine skin was treated with the Lux1540/10, Lux1540 Zoom and Lux2940 with 500 optics. Horizontal (radial) sections of biopsies were obtained and processed with H&E and NBTC staining. Digital images of the histologic sections were taken in either transmission or reflection illumination and were processed using the SAFHIR program. RESULTS: NBTC- and H&E-stained horizontal sections of ex vivo skin treated with ablative and non-ablative fractional devices were obtained. Geometric parameters, such as depth, diameter, and width of the coagulated layer (if applicable), and micro-columns of thermal damage, were evaluated using the SAFHIR software. The feasibility of objective comparison of the performance of two different fractional devices was demonstrated. CONCLUSION: The proposed methodology provides a comprehensive, objective, and efficient approach for the comparison of various fractional devices. Correlation of device settings with the objective dimensions of post-treatment damage profiles serve as a powerful tool for the prediction and modulation of clinical response.

Pilot investigation of the correlation between histological and clinical effects of infrared fractional resurfacing lasers.

METHODS: Yucatan Black pig skin was treated with a 1,540-nm erbium (Er):glass laser (Lux1540, 15 and 30 mJ) and two 1,550-nm Er-doped fiber lasers (Fraxel SR750 and SR1500, 8, 10, and 12 mJ). Histologic sections were examined to determine the depth of damage and to correlate subjects' clinical response. Concurrently, six subjects with photodamaged skin received three split-face and ipsilateral dorsal hand treatments with the 1,540-nm Er:glass laser on one side and one of the 1,550-nm Er-doped lasers (Fraxel SR750) on the other. RESULTS: The 1,550-nm Er-doped lasers, using lower fluences and higher densities, produced shallower micro-columns than the 1,540-nm Er:glass device at higher fluences and lower densities (mean depths 250-275 microm vs 425-525 microm, respectively). Blinded assessors found greater overall improvement in pigmentation with the 1,550-nm Er-doped laser and better overall improvement in texture with the 1,540-nm Er:glass laser. CONCLUSIONS: Greater densities of shallower damage columns at lower energies may better improve pigmentation, whereas deeper injuries, using higher energies and moderate densities, may better improve texture. This pilot study did not compare similar fluences and histologic damage between the two systems, and newer available systems allow for greater depth of penetration.

Micro-fractional ablative skin resurfacing with two novel erbium laser systems.

BACKGROUND AND OBJECTIVES: Fractional ablation offers the potential benefits of full-surface ablative skin resurfacing while minimizing adverse effects. The purpose of this study was to evaluate the safety, damage profile, and efficacy of erbium fractional lasers. MATERIALS AND METHODS: Histology from animal and human skin as well as clinical evaluations were conducted with erbium YAG (2,940 nm) and erbium YSGG (2,790 nm) fractional lasers varying pulse width, microbeam (microb) energy, number of passes, and stacking of pulses. RESULTS: Single-pulse treatment parameters from 1 to 12 mJ per 50-70 microm diameter microbeam and 0.25-5 milliseconds pulse widths produced microcolumns of ablation with border coagulation of up to 100 microm width and 450 microm depth. Stacking of pulses generated deeper microcolumns. Clinical observations and in vivo histology demonstrate rapid re-epithelization and limited adverse side effects. Facial treatments were performed in the periorbital and perioral areas using 1-8 passes of single and stacked pulses. Treatments were well-tolerated and subjects could resume their normal routine in 4 days. A statistically significant reduction in wrinkle scores at 3 months was observed for both periorbital and perioral wrinkles using blinded grading. For periorbital treatments of four passes or more, over 90% had > or =1 score wrinkle reduction (0-9 scale) and 42% had > or =2. For perioral wrinkles, over 50% had substantial improvements (> or =2). CONCLUSION: The clinical observations and histology findings demonstrate that micro-fractional ablative treatment with 2,790 and 2,940 nm erbium lasers resulted in safe and effective wrinkle reduction with minimal patient downtime. The depth and width of the ablated microcolumns and varying extent of surrounding coagulation can be controlled and used to design new treatment procedures targeted for specific indications and areas such as moderate to severe rhytides and photodamaged skin.