Monitoring thermally induced phase transitions in connective tissues by use of fluorescence micro-imaging analysis

Thermal modifications induced in corneal stroma were investigated with the use of fluorescence microscopy. Tissue samples were heated in a water bath at temperatures in the 35-90°C range. Fluorescence images of the structural modifications induced were acquired after staining with Indocyanine Green (ICG). Discrete Fourier Transform (DFT) and entropy analyses of each image made it possible to characterize the thermally-induced phase transitions in the stroma, and to indicate a threshold value for high thermal damage. The procedure could be proposed as the basis for a real-time controlling system for surgical techniques based on induced thermal effects.