Hi there, I am Dr. Deepak, I work in Emergency Department, where I see many patients with injury to their head. As you mentioned you had injured your head years back due to violent assault and you took major blow to the head. since then you are having dent more towards left side. now you having lazy left eye. I strongly feel there is no connection between the two. As the lazy eye started to happen now and injury to your head happened years before. This thing can happen with problem inside the brain, or with the nerve connecting muscles and brain,or with the muscle itself. And the cause is new, not related to injury to your head. I would recommend you to show a neurologist, and take his opinion regarding it, he will examine and do some test related to it. If he is not able to figure out the problem, then you should show an eye specialist. Thank you, I hope your concern was dealt with and hope you have speedy recovery.