PubMed · 8257560
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S Leikin, V A Parsegian, D C Rau, R P Rand. 1993. Hydration forces.. https://doi.org/10.1146/annurev.pc.44.100193.002101
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BACKGROUND AND OBJECTIVE: The clinical use of lasers to cut and coagulate tissue necessitates a better understanding of how the residual thermal damage affects healing. This study was designed to evaluate the effects of varying degrees of thermal damage on the healing process. STUDY DESIGN, MATERIALS AND METHODS: Partial-thickness lesions were created in guinea pig skin using an Er:YAG laser, a Ho:YAG laser, and a scalpel. To monitor recovery of the stratum corneum, water flux from the wound sites was quantified and histological data obtained for approximately one week. RESULTS: The data indicate an exponential water loss pattern from all wounds. Water flux from the scalpel- and the Er:YAG laser-induced wounds was initially high but decreased rapidly with decay rates (mean +/- SE) of 0.46 +/- 0.01 day-1 and 0.38 +/- 0.01 day-1, respectively. The Ho:YAG laser-induced wounds demonstrated a different pattern of decay with lower water flux values initially and a decay rate of only 0.13 +/- 0.01 day-1. CONCLUSION: Histological and water flux data reveal that Er:YAG laser-induced wounds achieve epidermal integrity only slightly after scalpel-induced lesions, and Ho:YAG laser-induced wounds heal substantially slower and contain more granulation tissue.
BACKGROUND AND OBJECTIVE: Interstitial laser treatment (ILT) of the ovary might be a new surgical approach to restore ovulation with a minimal risk of adhesion formation in patients with chronic hyperandrogenic anovulation who are unresponsive to hormone therapy. The objective was to investigate the feasibility of inducing a lesion limited to the center of the ovary in an animal model. STUDY DESIGN/MATERIALS AND METHODS: ILT was performed in seven goats using Nd:YAG laser in combination with ultrasound monitoring. The extent of direct thermal damage was investigated in two goats, treating both ovaries during a laparotomy at 2, 4, 6, and 8 W, respectively, for 5 min. Adhesion formation was evaluated in five goats 81 days after an unilateral laparoscopic ILT at 1, 2, 4, 6, or 8 W for 5 min. During treatment temperatures on the surface of the ovary were measured. RESULTS: Histology after 1 day showed sharply demarcated necrotic lesions located centrally or subcapsularly at low powers, whereas at higher powers the lesions extended to the surface of the ovary. At low powers no adhesions were observed, whereas higher powers resulted in periovarian adhesions. Temperatures measured on the ovarian surface during treatment ranged between 38 degrees C and 90 degrees C. Ultrasound monitoring of the extent of thermal damage failed due to poor positioning. CONCLUSION: Although this pilot study does not warrent firm conclusions, the results indicate that ILT of the ovary is feasible and that lesions without adhesions can be produced at low powers. The use of ultrasound to monitor the extent of thermal damage in the ovary should be a subject of further evaluation.
BACKGROUND AND OBJECTIVE: This work studied the ablation mechanisms of rabbit corneas by the Erbium:YAG laser. The occurrence of thermal and mechanical damages in the tissue as a function of the laser fluence was also investigated. STUDY DESIGN/MATERIALS AND METHODS: The experiments were performed both on enucleated eyes and in vivo. An ultrafast imaging technique was used to investigate the dynamic evolution of the ablation. The treated samples underwent histological and ultrastructural study. RESULTS: A single high fluence laser shot led to the complete removal of the epithelium by a photomechanical effect. In eyes whose epithelium was manually removed, high fluence pulses resulted in evident tears in the stroma, whereas low fluence pulses led to few microns deep incisions, characterized by limited mechanical and thermal damages. CONCLUSION: The photomechanical action plays a significant role in the ablation of the cornea by Erbium laser. Precise control of the fluence is required to avoid cracking phenomena in the stroma.