Potentials of microfluorimetric techniques in basic and applied research in ophthalmology: an application to the study of photosensitizer localization in lens epithelial cells

Microfluorimetric techniques are nowadays widely used as a diagnostic tool in basic and applied research in biomedicine. They can be employed to study both endogenous and exogenous fluorophores. In the first case, direct indications are obtained on the biomolecules of interest, whereas in the second case indirect information can be deduced on the cellular structures interacting with the fluorophores used as the markers. Moreover, in the case of fluorescent drugs, such as most photosensitizers, microfluorimetric techniques can be exploited to determine the localization sites of the drug itself. Due to the complexity of biological systems, discrimination of the single fluorophores merely based on cw excitation and emission spectral analysis is not always possible. Thus, combination with time-resolved fluorescence analysis can give important additional indications. The potentials of these techniques in ophthalmological research are discussed. The paper reports, as an example of application of time-resolved microfluorimetric techniques, the study of the localization of Photofrin II, a widely used photosensitizing drug, in lens epithelial cells. Indeed, a photodynamic therapy of lens epithelial proliferation frequently following primary cataract surgery has recently been proposed. The potentials of this therapeutic approach strongly depend on a very efficient drug targeting. Microfluorimetric techniques proved very useful to identify the drug localization sites in a series of experiments performed using young adult rabbits as the animal model.