A concussion can cause blurred vision due to the intracal hydroncus, which presses the optic nerve. Under such circumstance, I advise you to go to the hospital for an examination and a treatment without delay. The main manifestation of a concussion is a loss of consciousness, which is not serious in general and lasts a short time, less than half an hour. A concussion can lead the wounded to forget what has happened recently, such as things happened fore and after the incident, but he still could recall clearly what happened in the past. In addition, when the sufferer come to himself after a concussion, he may feel an headache, dizzy, feel like vomiting, but such symptoms are slight and will not cause the wounded upset.