3315 Confocal in vivo probing of proteins and water in the rabbit cornea

Puroose: To develop an instrument with high spatial resolution probing chemical composition of comeal tissue in live animal model without interference of signals originating from adjacent tissues. Methods: A Raman probe for in viva studies was developed that has the required resolving power in space, obtained by a confocally placed fiber for transportation of the Raman signai. Resolving power in time. to suppres movement artifacts, was obtained by a microcope objective with a high light gathering power and a long working distance. Rzsults: fn viva Raman spectra of protein and water collected along the optical axis of the excitation beam were obtained from rabbit corneas at exposure times of 1 s at spatial intervals of 70 pm with a resolution in depth of 30 or 150 pm. Conclusions: The shallow probing depth of 30 pm proved to have enough spatial and temporal resolution to perform reliable measurements of the protein and water gradients in the comeal tissue in an animal model. However, for measurements where gradients are not relevant, the 150 pm probing depth, that requires less radiation energy, i:r adequate for intra comeal measurements.