Constricted pupils are the parasympathetic normal neurologic response to light shining on the retina. It is called the Pupillary light reflex.
Dilated pupils are a normal sympathetic nervous response to poor lighting, alarm or startle responses, or use of stimulants such as cocaine or amphetamine analogs, known as sympathomimetic drugs. Dilated pupils despite light shining into retinae may indicate increased intracranial pressure caused by or leading to cranial nerve or brain injury.
Roth's spots on the retinae are indicative of retinal hemorrhage, often due to endocarditis (heart valve infection), cancer (leukemia), or diabetic vessel damage. This sign us due to a more chronic condition than acute head injury.