Applications of Raman spectroscopy to ophthalmology: Spectroscopic characterization of disposable soft contact lenses

Modification of surface morphology of hydrogels due to subsurface femtosecond laser micromachining

In this paper, we studied the effects of subsurface femtosecond laser micromachining on surface morphology in hydrogels. Depending on material properties and writing conditions, we found surface bumps when materials were hydrated, and trenches when they were dehydrated, which can be attributed to the localized change in water concentration. Such wavy surfaces by laser-induced refractive index change are not desirable in clinical contact lenses. Therefore, the minimization of surface bumps is necessary to ensure the user eye wearing comfort. In addition, we examined the optical effects of the surface features using interferometry and the surface morphology using profilometry. Finally, we proposed a simplified mechanical model based on localized swelling.

Experimental study of the mechanisms leading to the formation of glistenings in intraocular lenses by Raman spectroscopy

The phenomenon of glistenings, often appearing in intraocular lenses (IOLs) of patients after some time from the surgical operation, is potentially able to induce a poor quality of vision and, therefore, frustrate IOL implantation itself. In this paper, we combine optical microscopy with micro-Raman spectroscopy to get a deeper insight on the mechanism ruling, at microscopic scale, glistening formation. In particular, we have analyzed two types of IOLs, characterized by a different internal hydrophobicity but a similar polymer hydration coefficient. Raman imaging of single microvacuoles reveals that water creeps into the polymeric network, which traps water. Finally, applying the Principal Component Analysis (PCA) to Raman data, we provide information on the probable mechanism leading to water trapping in the two kinds of analyzed IOLs.

Optical and vibrational properties of phosphorylcholine-based contact lenses-Experimental and theoretical investigations

The Raman, MIR and UV-vis spectroscopy have been used to characterize Omafilcon A material constructing the one of the Proclear family contact lenses. The Omafilcon A is hydrogel material composed of 2-hydroxyethyl methacrylate (HEMA) and 2-methacryloyloxyethyl phosphorylcholine (PC) polymers crosslinked with ethyleneglycol dimethacrylate (EGDMA). Vibrational and electronic properties of the Omafilcon A material were also investigated by quantum chemical calculations. Experimentally obtained Raman, MIR and optical spectra were compared to the theoretical ones calculated applying RHF and DFT methodology. The quantum chemical calculations were performed for isolated monomers of lenses compounds as well as for their dimers and trimers to elucidate the effect of Omafilcon A polymerization and the role of an individual components.

Structural modifications induced by an in vitro maturation process in zona pellucida glycoproteins of bovine oocytes. A Raman microspectroscopy analysis

Raman microspectroscopy is useful for discrimination between immature and in vitro matured bovine oocytes. Modifications in the glycoproteins of the zona pellucida exerted by the maturation methods might influence the process of in vitro production.