current research interests

My current research at the department of ophthalmology at the University of Jena is focused on the development of non-invasive optical diagnostic techniques for the early detection of ocular fundus diseases and on surgical application of femtosecond pulse-lasers.

Because of it's anatomical peculiarities, the eye is accessible by optical methods in diagnostics as well as therapy more than any other organ. Nowadays, we find a wide range of surgical application of lasers in ophthalmology, using photomechanic al and photochemical effects. Different properties of the light are exploited in modern ophthalmic diagnostics: The state of polarization of the light reflected from the ocular fundus is used for the determination of the thickness of the retinal nerve fiber layer, the coherence is exploited in optical coherence tomography (OCT) and the reflection and fluorescence spectra carry information on metabolite concentrations.

The goal of my work of the last years was the investigation of physiologic and pathologic metabolic states by reflection spectroscopy. An imaging ophthalmo-spectrometer for clinical use was developed and tested. A mathematical model for the determination of the concentrations of metabolites (melanin, xanthophyll, and hemoglobin) was developed on the basis of the Adding-Doubbling method known from astrophysics. You can download a Mathematica-implementation of this method for the calculation of the reflection and the transmission of a stack of layers with different optical properties. In order to feed the model with realistic scattering data for the ocular fundus tissues, these were determined in vitro as well as in vivo by OCT. Currently, my work is focused on the integration of coherent and non-coherent reflectometry.

An important clinical application of the method is the spectrometric measurement of the oxygen saturation of blood inside retinal vessels. Since this needs a radiation transport model too, the scattering and absorption properties of blood cells were investigated and a Monte-Carlo simulation was performed. Furthermore, the measurement using polarized light was investigated.

Besides these own research activities, I am involved in the research of the experimental ophthalmology group at the clinic, which is concentrated on the attendance at clinical studies, in time-resolved fluorescence measurements, and in laser surgery.