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UBC Theses and Dissertations

Spatially selective photothermolysis guided by reflectance confocal microscopy for precise vessel closure in mouse eye limbus Jiang, Liwei


Laser photocoagulation of corneal neovascularization (NV) is currently based on conventional selective photothermolysis in which the laser energy can be physically confined in the abnormal blood vessels by choosing appropriate wavelength and pulse duration, and thermally denatures the target vessels. However, because this technique primarily relies on the differential absorption between the targeted chromophore and its surroundings, it may not be sufficiently selective at the microscopic level. For achieving precise microscopic treatment, a spatially selective photothermolysis (SSP) method has been developed by our group utilizing femtosecond laser-based two-photon absorption under the guidance and monitoring of reflectance confocal microscopy (RCM). Since two-photon absorption occurs only at the focal volume of the treatment laser beam, the vascular target can be treated precisely while minimizing the collateral damage to surrounding tissues. In this thesis, we aim to develop an experimental setup that facilitates SSP treatment on the corneal edge of normal mice under RCM guidance. We hypothesize that our RCM imaging-guided two-photon absorption based photothermolysis system could be used for selective vessel closure in mouse limbus with minimal collateral damage to its surroundings. The video rate, high-resolution RCM imaging system was integrated with an adjustable field of view (FOV) white light imaging for target selection. A mouse head holder and an eye stabilizer were developed to reduce the involuntary movement of the mouse eye and achieve stable corneal imaging. The RCM imaging-guided SSP treatment system was developed and demonstrated to perform normal vessel closure in mouse limbus. Multiphoton microscopy (MPM) imaging, including two-photon fluorescence (TPF) imaging and second harmonic generation (SHG) imaging, has been performed before and after SSP treatment for assessing the tissue alternation within and outside the focal volume during laser irradiation. With all the successful results, we believe that the two-photon absorption based SSP method could provide precisely localized blood vessel closure on mice limbus and has great potential to be used for therapeutic applications in the treatment of corneal NV and other eye diseases such as ocular melanoma.

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