1. Institute of Ophthalmology, University of Parma, Parma, Italy.
2. Dipt. Salute Animale, Facoltá di Medicina Veterinaria, University of Parma, Parma, Italy.
3. Ophthalmology Division, Hospital of Carpi (MO), Carpi, Italy.
4. Institute of Human Pathology, University of Modena, Modena, Italy.