It will take from three days to a few weeks to clear up according to the intensity of the injury. Generally speaking, there is no need for you to take any action to get rid of the blood clot in the eye because it usually heals on its own. You just need to take some rest and wait the body to reabsorb the clot in the eyes, and then you will be ok. But remember not to rub your eyes before the blood clot subsides because it can increase the risk of rebleeding.
So, a blood clot could be resulted from physical injury or some problems with your eyes, in a word, the reasons for it could be complicated. However, once got the blood clot, you should follow the doctor's advice and get eye drops on a regular basis, try to take a surgery if necessary. Generally speaking, it could last for about one month, based on your situation.