Why can’t I donate blood if I am highly myopic? Xiao Li, who just turned 18 this year, planned to do what an adult should do – donate blood for free. However, the staff at the blood donation station could not let Li get what he wanted because his myopia was approaching 800 degrees. Li wondered how blood donation could be related to myopia. Why can’t people with high myopia donate blood? The reason for not allowing highly myopic patients to donate blood is for the good of the patients themselves, but many people feel very strange. In fact, it is true that high myopia patients can add a burden to their eyes if they donate blood. People with high myopia (600 degrees or more) are generally not encouraged to donate blood, while those with mild myopia who are in good health can donate blood. Highly myopic people cannot donate blood mainly because it will affect the blood vessels in the eye. Myopia is a refractive eye abnormality, generally speaking, mild myopia (less than 300 degrees) complications are rare, while high myopia (more than 600 degrees) the anterior and posterior diameters of the eye significantly longer, but the retina and choroid can not be correspondingly longer, resulting in the retina, choroid is elongated and diffuse atrophy, the corresponding blood vessels have become more delicate, so that the blood vessels are very sensitive to changes in blood pressure, while the eye The vitreous humor may change from a gel to a liquid state. For highly myopic people whose blood vessels are stretched and slender, the slight fluctuation of blood pressure may cause the blood vessels in the fundus to spasm, resulting in fissures in the already diseased retina, at which time the liquefied vitreous body will take the opportunity to enter the subretina, causing retinal detachment and seriously affecting vision. Therefore, from the perspective of protecting blood donors, highly myopic people should not donate blood. Experts say that myopic blood donors are not uncommon on a daily basis. Since the degree of high myopia is not clearly defined in China’s blood donation standards, taking into account factors such as astigmatism, the general practice usually takes about 600 degrees as a benchmark for grasping and patiently persuading highly myopic blood donors. Possible Complications for Highly Myopic Patients In addition to the dangerous conditions mentioned above, highly myopic patients can suffer from these terrible complications when donating blood. Flying mosquito syndrome People with this disease often see dark shadows fluttering in front of their eyes as they turn, like flies flying around, due to the liquefaction of the normal colloid-like structure of the vitreous humor. Macular hemorrhage In highly myopic people, the constant pulling on the wall of the eye caused by the enlargement of the eye will cause metabolic disorders in the normal relationship between the retina and the choroidal tissue in the fundus, especially when the small blood vessels in the macular area rupture due to pulling and other factors, causing macular hemorrhage and causing great damage to the central vision. At this time, the patient feels that there is a fixed black shadow in front of his eyes blocking his vision. Although the hemorrhage can be absorbed with treatment, it will always leave more or less blood marks and affect vision. Retinal detachment This is a more serious complication, and the cause of its development is more complex. Internally, the retinal tissues of highly myopic patients become fragile due to degeneration and atrophy, which makes it easy for the retina to detach and cause blindness. The external cause is the sudden impact of external force, which is transmitted through the vitreous humor and causes the retina to rupture, resulting in retinal detachment and blindness.