Autologus serum tears are made from the serum of your own blood. Because of the natural properties including growth factors, proteins, vitamins, and antioxidants, autologous serum drops are most like the natural tear and aid in healthy growth and healing of the ocular surface. This makes them a more effective replacement than manufactured artificial tears. Autologus serum tears are made after a blood donation. Once the red blood cells and clotting factors are removed, the blood serum is left behind and diluted with a sterile, preservative-free solution to produce a tear substitute that is unique to the patient. Since blood and tears have an almost identical salinity and pH, there is no issue of burning or stinging upon installation. Because they are non-preserved, the drops are stored in the freezer until you need them.