A Prospective, Randomized, Doubled-masked, Single Center, Clinical Comparison of Autologous Serum, Heterologous Serum and Umbilical Cord Serum Eye Drops in the Management of Dry Eye Syndrome

To valuate tear film and ocular surface changes after autologous serum therapy, heterologous serum therapy and umbilical cord therapy in patients with severe dry eye syndrome. To accomplish clinical comparison of the effects between the three therapies.