Yes, it could cause that. The retina can become detached from the eyeball and can cause flecks in the vision, light flashes or the appearance of a curtain over your vision. Retinal detachment can be caused by a variety of factors, blow head is one common cause. Because the retina is the light-sensitive membrane that covers the back of the eyeball, direct trauma to the eye, such as a blow by a fist or stone can cause the retina to detach. And indirect trauma, such as a blow to the head can also result in retina detachment. Due to the movement of the vitreous that is the fluid in the eye, retinal detachment can occur.
What your friend says can be true. The retinal detachment can be easily happened among the persons with high prescription. Once the eyes get the deep short-sighted problem, their corneal will be thin. The small little serious movement will cause the retinal detachment, like blowing your head. Once getting the retinal detachment, your friend should go to the hospital to get the treatment as soon as possible.
Yes, blow head can lead to retinal detachment. Generally speaking, a strong blow to the head can cause the retina to pull away from its underlying wall. In that way, once the retina has started to detached, the fluid from the Vitreous flows in the small tears in the retina can occur. And then retina will start to detach. Anyway, it can be kind of dangerous. So just be careful about it. And you should know that there are many other factors which can lead to retinal detachment, such as eye injury, severe high blood pressure. On the other hand, most people with detached retina risk factors will not develop a detached retina. So you should not worry about it too much. If you have some questions about it, just ask your doctor, he can give you the professional answer.