Thalassemia, also known as sickle cell anemia, was first described by Herrick in 1910. He found "sickle" cells in the blood of a black person with hemolytic anemia. Because it first occurred in countries along the Mediterranean Sea, it is also called Mediterranean anemia. Later, it was found to occur all over the world except the Mediterranean Sea, and it is also called thalassemia. This is a hemoglobin genetic defect disease with a complex genetic basis. There can be many different gene mutations. It is a group of diseases with quite impure hemoglobin synthesis disorders. It can be divided into homozygous and heterozygous, and it can also be combined with other abnormal hemoglobin to form a double heterozygous state. This disease can be divided into several types, such as sickle cell thalassemia, referred to as Sthal disease; sickle cell anemia, or SS disease; sickle cell C disease, referred to as SC disease; sickle cell trait, also known as AS hemoglobin disease, etc. The severity of eye lesions varies with different types, with Sthal and SC types having the most serious complications.