| Abstract |
Within the last 20 years, there has been a great development concerning the area of the refractive surgery with the use of excimer lasers, due to its great predictability and the high percentage of the successful outcome. The refractive surgery is one of the most successful and safe operations performed nowadays, due to the predictability of the procedure.
Due to the fact that, the refractive surgery with excimer laser is a relatively new technique, there are still some aspects which need to be improved and many factors which influence the outcome of the procedure that need to be thoroughly investigated. One of the factors, with a major influence at the outcome of the refractive surgery, is the corneal hydration degree during the procedure. Important variations of the cornea’s hydration from the mean value, result in overcorrecting or undercorrecting the refractive error. Until now, no successful and safe way to estimate the corneal hydration during the procedure has been found.
In this thesis, was investigated the possibility of using the emission spectrum produced during the laser- cornea interaction to estimate the corneal hydration. The experiments were held with the use of two excimer lasers: KrF and ArF (emission wavelengths 248nm and 193nm respectively, pulse duration 10 nsec). At the first part of the experiments, the KrF laser was used in order to investigate and understand the mechanisms that take place during the laser-cornea interactions. For the purpose of the experiments, samples from pork and rabbit corneas and also a material which simulates the cornea known as PALM, were used.
Many aspects concerning the laser-cornea interaction were investigated as part of this research. Some of them are:
1) The possible relation between the spectroscopic features to the corneal hydration degree.
2) The fluorescence spectrum of the cornea emitted due to its irradiation with excimer laser, in order to identify the elements in the cornea, which emit fluorescence.
3) Spectra from different layers of the cornea were recorded and compared in order to investigate any similarities or differences.
4) It was investigated whether the emission spectrum of the cornea was power-dependant
5) It was investigated the effect of spot position on the cornea to the shape and the intensity of the spectra.
During the present study, important information about the mechanisms that take place during the laser-cornea interactions, were obtained. The most important outcome of this research was the observation that the emission spectrum depends upon the hydration degree of the 5
cornea. Based on the outcome of this study, it is believed that more studies should be done on this area in order to investigate in a more complete way the advantages of recording on line, the emission spectrum from the cornea due to its irradiation. This method seems to have all the aspects in order to lead to the design of a complete system with appropriate software which will be capable to provide knowledge of the hydration degree of the operated cornea during the refractive surgery procedure.
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Χρήση φασματοσκοπικών τεχνικών για την εκτίμηση της ενυδάτωσης του κερατοειδούς κατά την διάρκεια διαθλαστικής χειρουργικής
