Occipital lobe
The occipital lobe is one of the four major lobes in the brain's cerebral cortex. It is located at the back of the head (see attached image). The occipital lobe's primary function is processing and making sense of visual information we receive through our eyes. Damage or trauma to the occipital lobe (in John's case when he got hit on the back of his head) can cause temporary or permanent vision impairment, subject to the severity of the trauma.
