Pupillary signs in a comatose patient

Pupil characteristics can be used to identify the cause of coma in a patient. It also helps in determining the treatment. The important pupillary signs are given below:

Pupil Condition
Pinpoint pupils Pontine lesion / morphine poisoning
Moderately dilated, non reactive, fluctuating Mid brain lesions
Unilateral dilated, non reactive Third nerve damage – due to transtentorial herniation of temporal lobe / traction of third nerve against posterior cerebral artery
Bilateral dilated, non reactive Terminal states / Ischemic brain damage / Atropine / Belladonna poisoning
Small, equal, reactive Toxic / Metabolic causes of coma