Yes, it is quite possible to happen. According the resources, many people might have some uncomfortable feelings after blood donation, but actually reaction to blood donation is rare. About 2% of donors have adverse reaction to donation, and most of them are very minor. And some of them are have reaction due to the rapidly decreased blood pressure, which is referred as Hypovolemia. Symptoms of hypovolemia include fainting, rapid breathing or heart beating, coldness and paleness of skin. Some people have adverse reaction because of the sodium citrate used to keep blood from clotting. It is called hypercalcemia. Direct impact on eyes or visions is very rare. Based on your description, it is probably related to the two situation stated above. Yet you don't have to worry too much. These symptoms usually go away very quickly. After donation, you should drink a lot of warm water, and milk. Have a good rest is important too. There are many people around the world are encouraged to donate blood, and there is very rare of cases that donators have any long-term complications as long as if the equipment uses is clean and sterilized. So, don't worry, you will recover very soon.
