Selective disruption of vascular endothelium of zebrafish embryos by ultrafast laser microsurgical treatment.

In this work, we demonstrate that ultrafast laser irradiation could selectively disrupt vascular endothelium of zebrafish embryos in vivo. Ultrafast lasers minimize the collateral damage in the vicinity of the laser focus and eventually reduce coagulation in the tissues. We have also found that the threshold fluence for lesion formation of the vascular endothelium strongly depends on the developmental stage of the embryos. The threshold laser fluence required to induce apparent lesions in the vascular structure for Somite 14, 20 and 25 stages is about 5 J/cm(2) ~7 J/cm(2), which is much lower than that for the later development stages of Prim 16 and Prim 20 of 30 J/cm(2) ~50 J/cm(2). The proposed method for treating the vascular cord of zebrafish embryos in the early stage of development has potential as a selective and effective method to induce a fatal lesion in the vascular endothelium without damaging the developed blood vessels.

Femtosecond laser-assisted selective reduction of neovascularization in rat cornea.

Nonlinear multiphoton absorption induced by focusing near infrared (NIR) femtosecond (fs) laser pulses into a transparent cornea allows surgery on neovascular structures with minimal collateral damage. In this report, we introduce an fs laser-based microsurgery for selective treatment of rat corneal neovascularizations (in vivo). Contiguous tissue effects are achieved by scanning a focused laser pulse below the corneal surface with a fluence range of 2.2-8.6 J/cm(2). The minimal visible laser lesion (MVL) threshold determined over the corneal neovascular structures was found to be 4.3 J/cm(2). Histological and optical coherence tomography examinations of the anterior segment after laser irradiations show localized degeneration of neovascular structures without any unexpected change in adjacent tissues. Furthermore, an approximately 30 % reduction in corneal neovascularizations was observed after 5 days of fs laser exposure. The femtosecond laser is thus a promising tool for minimally invasive intrastromal surgery with the aid of a significantly smaller and more deterministic photodisruptive energy threshold for the interaction between the fs laser pulse and corneal neovascular structures.