1. Optical Diagnostic Techniques Group, Theoretical, Atomic and Optical Physics Department, University of Valladolid, Valladolid, Spain
2. Ophthalmology Department, Hospital Clínico Universitario de Valladolid, Valladolid, Spain
3. Cell Biology, Histology and Pharmacology Department, Faculty of Medicine, University of Valladolid, Valladolid, Spain
4. Instituto Universitario Fernandez-Vega, Universidad de Oviedo, Oviedo, Spain