1. Faculty of Physics, Adam Mickiewicz University, ul. Uniwersytetu Poznanskiego 2, 61-614 Poznań, Poland
2. Department of Optometry, Poznan University of Medical Sciences, ul. Rokietnicka 5d, 60-806 Poznań, Poland
3. School of Biochemistry, Medical Sciences Building, University of Bristol, University Walk, Bristol, BS8 1TD, U.K.