You should not be having an optometry exam, which is an evaluation by an optomitrist.
Youn should be having an opthamalogical exam, which is an examination by an M.D. who specializes in the eye.
The exam won't affect the outcome of the concussion, in any event.
The medication that dilates the pupils wears off in a few hours.
Hi there. I would like to suggest that you pursue your head injury and the concussion first. Consult a neurologist first and get an MRI scan done and visualize any collected blood and correlate clinically. The symptoms have to be checked against MRI findings and any details missed on either. Fix an appointment with the optometrist at a later date, say a wee later, if it was just for errors of refraction. Take care.