After three hours the patient fully awakens and states that he cannot see, although he seems only minimally agitated by this situation. He is refusing to provide further information on his ingestion. On examination, the patient has no light perception, and his pupils are noted to be 6-7 mm and minimally reactive. His extraocular movements and funduscopic examination are normal. There is no sign of extraocular trauma, no chemosis, and his intraocular pressures are normal by tonometry.
Opticokinetic nystagmus is absent.
Many drugs and toxins are known to cause blindness infrequently. For example, vasodilators can reduce blood pressure to such an extent that an occipital cortical infarct occurs. However, hypotension induced infarction is unlikely in a young patient with presumed normal vasculature, but may be encountered in a more elderly patient. In addition, carbon monoxide and hydrogen sulfide may produce cortical blindness. In these cases, the pupillary reflex should be normal despite complete loss of vision.