A patient’s eyes turning blue can be caused by scleral hypoplasia, iron deficiency, and a large loss of pigment in the iris. If the patient’s sclera is underdeveloped, because the sclera is thin, the blood vessels inside the patient’s eyes can be observed through the sclera, so the patient’s eyes may appear blue. If the patient is in a state of iron deficiency for a long period of time, it may cause insufficient collagen synthesis in the sclera area, thus making the sclera thinner, and the patient’s eyes may appear blue under natural light observation. If the patient loses a lot of iris pigment, it may cause the patient’s eye color to become pale, which may lead to the patient’s eyes appearing blue. In addition to the above, if the patient has a high degree of myopia or congenital glaucoma and other diseases, it can also lead to blue eyes. It is recommended that patients with bluish eyes and other discomforts seek medical attention to evaluate their condition and follow the doctor’s instructions for treatment.