Hello there. My question comes on behalf of my younger brother, who recently sustained a head injury that was thought to be a concussion, though no official diagnosis was sought. About a week has passed since the incident and he has started to complain about minor headaches, a symptom that had him sent to his school nurse yesterday, who noticed a disparity in the size of his pupils as the right one was slightly larger than the left. After multiple members of our families confirmed the abnormality, we took him to a doctor who promptly tested his eyes for reactivity, among others thing, and declared him to be perfectly fine. Having worried about the kid all night, this seems like great news but not having been there to hear the doctor myself, some reinsurance would be welcomed. Is there any chance that he could have a serious problem that could feasibly go unnoticed by a professional?