Foremost, I would like to express my sincere gratitude to my Pprofessor, Amira Abd El-Mageed Abd El-Azeem, Professor of Ophthalmic-Genetics, at the Research iInstitute of Ophthalmology, for her patience, supervision, advice, and guidance allduring the time of research and writing of this thesis, as well as, giving me extraordinary experiences throughout the work. Above all and the most needed, she provided me unflinching encouragement and support in various ways. Her immense knowledge which  exceptionally inspired and enriched my growth as a student, a researcher and a scientist that I want to become.