anisocoria indicates a difference in pupil diameter ; in common clinical manifestations , if anisocoria is more marked in bright light , the large pupil is abnormal , while if anisocoria is more marked with reduced illumination , the small pupil is abnormal . besides , a pupillary diameter difference less than 1 mm is often a physiological condition occurring in about 20% of the population . systemic causes are neurological or vascular disorders , usually associated with raised intracranial pressure or a consequence of traumatic or hypoxemic lesions of the parasympathetic and orthosympathetic nervous system . 2 local causes reported in literature are synechia , congenital iris disorders ( coloboma and aniridia ) and pharmacological effects . 3 a rather rare occurrence is intravascular embolization of local anesthetics containing vasoconstrictors . in the clinical practice , an intraoperative or postoperative anisocoria is assessed according to its cause . knowing this clinical event and the rapid identification of the trigger factor is the basis of a correct and timely therapeutic approach , which , in severe cases , could save the patient 's life . we present a case of a 47-year - old man , suffering from spastic tetraparesis . the intraoral examination revealed destructive decay of tooth number 12 and necrotic residues of teeth 15 and 27 ( fig . 1 ) . being a disabled and non - collaborating patient , the authors prepared oral surgery under general anesthesia . in the 24 hours before surgery , the patient was monitored with hematological examinations ( complete blood count , hemocoagulative pattern , phlogosis indexes and serum protein electrophoresis ) , electrocardiogram , orthopantomography of dental arches , chest radiography ( with the patient seated ) and intraoral and extraoral examination . in this case , preoperative examinations did not reveal noteworthy clinical conditions . in the light of the subsequent occurrence , we report an equal size of the patient 's pupils ( isocoria ) on the day before surgery , and the pathological case history did not reveal previous vascular disorders or traumas of the intracranial district . on the day of surgery , anesthetists prepared the patient with midazolam 5 mg and atropine 0.5 mg . after the preoperative phase , general anesthesia was performed as follows : propofol 150 mg together with fentanyl- , muscle relaxants midarine 75 mg and cisatracurium 10 mg , and sevoflurane 0.5% ; in the postoperative course , anesthetists administered ephedrine 5 mg and ketorolac 3 mg . the dental treatment was simple avulsion of the above - mentioned teeth : after plexus anesthesia ( 2 phials of hydrochloride mepivacaine 3% ) without vasoconstrictor , we avulsed tooth 12 and the necrotic residues of teeth 15 and 27 , and scraped the post - avulsion alveolus with volkmann spoon . then the post - extraction alveoli were closed with a resorbable suture . after the surgical procedures , there were no signs of iatrogenic lesions and we observed a correct hemostasis of the surgical site . recovery from drug - induced unconsciousness was induced after administering intrastigmine ( 2 phials ) and atropine 0.5 mg as decurarizing agents . on awakening , however , he developed severe anisocoria ; in particular , a ~4 mm diameter increase of the left pupil compared to the right pupil , although he had no visual impairment and a normal reaction to light stimulus . 2 ) the diagnostic hypothesis concerned the ophthalmic ganglion , even though vascular aneurysmal diseases could not be excluded . the embolization of anesthetic in peripheral blood vessels , as well as lesions to pyramidal and extrapyramidal nerve tracts , were immediately analyzed and considered incompatible with the treatment performed . in order to achieve diagnostic certainty , we performed computed tomography ( ct ) in the emergency setting , nuclear magnetic resonance ( nmr ) of the brain and magnetic resonance angiography of intracranial vessels . computed tomography revealed the presence of mild dilatation of the ventricular system , and we noted parenchymal , likely vascular involvement in the right capsulolenticular area and bilateral dilatation of the cerebral cortical sulci . the report of nmr described an on - axis ventricular system with an atrophic dilatation and a localized atrophy in the bilateral mesial frontal area , due to perinatal pathologies . after these instrumental examinations , we took digital pictures of the patient 's pupils every 60 minutes , in order to monitor the clinical situation . 6 ) the patient never had the clinical manifestation of the pupil abnormality again , and reported no pathological outcome after the described occurrence . physiologic anisocoria is believed to occur in about 20% of the population , but its incidence increases with age , occurring in about one third of the population above 60 years of age . 1 unilateral mydriasis can be caused by a contusion injury to the iris sphincter or by a direct trauma to the oculomotor nerve . 4 the traumatic injury can also be a lesion of the iii cranial nerve . 2 traumatic or hypoxemic injuries of the sympathetic nervous system may be the cause of horner 's syndrome , which refers to a group of signs produced when sympathetic innervation to the eye is interrupted . anisocoria caused by the side effects of active principles , especially those of topically administered drugs , is a common condition . in general , atropine - like drugs can cause drug - induced mydriasis , while parasympatholytics can cause drug - induced myosis . the experience of ophthalmic medicine in using eye drops for glaucoma treatment proved that the cholinergic action of certain active principles could alter the pupil diameter . in case of accidental contact with the eye , these principles can lead the clinician to make a wrong diagnosis of anisocoria of neurogenous or vascular origin . some of the active principles of the most common eye drops used for glaucoma therapy are : dapiprazole : antiglaucoma psychotropic agent and selective alpha-1 antagonist . its miotic action results from the blocking activity on the sympathetic tone of the iris dilator muscle;moxisylyte : a selective alpha-1-adrenergic receptor blocker , causing a marked vasodilation that lasts for 3 - 4 hours;pilocarpine 3% - epinephrine 0,5% : the cholinergic action of pilocarpine reduces intraocular pressure . its miotic action results from the blocking activity on the sympathetic tone of the iris dilator muscle ; moxisylyte : a selective alpha-1-adrenergic receptor blocker , causing a marked vasodilation that lasts for 3 - 4 hours ; pilocarpine 3% - epinephrine 0,5% : the cholinergic action of pilocarpine reduces intraocular pressure . 5,6,7 some cases reported in literature confirm unilateral mydriasis after the spread of phenylephrine nose drops through the nasolacrimal duct . 8 unilateral mydriasis was also reported after using phenylephrine / lidocaine spray with a standard oxygen - driven face mask nebulizer . 9 literature shows that the cases of anisocoria reported during or after oral surgery are rare occurrences , especially in cases of simple tooth extraction . it also indicates the absence of a case history allowing the oral surgeon to make a differential diagnosis , in case he has to diagnose this clinical condition . among the few cases of anisocoria after oral surgery under general anesthesia , we report a unilateral mydriasis together with eye movement disorders in a patient treated with regional anesthesia with lidocaine and epinephrine for surgical removal of impacted third molars . 10 for investigation and diagnosis of unilateral pupil dilation , the main causes that a clinician should think of are a cerebrovascular accident , a neoplastic mass , a cerebral lesion or an ocular trauma . however , the present study also indicates the existence of minor factors , often ignored or unclear , that should be taken into consideration for differential diagnosis . anisocoria can manifest in more or less evident forms : therefore , it is clear that knowing this clinical condition is of crucial importance for a correct and timely resolution . once severe anisocoria ( l > r ) was confirmed in the described case report , the authors supposed that mepivacaine hydrochloride could have crossed the homolateral pterygopalatine fossa and the inferior orbital fissure in the left hemimaxilla , and then reached the eye socket and acted on the ciliary ganglion . unlike literature reports , this is a case of unilateral mydriasis after administration of local anesthetics with plexus infiltration . however , the patient had no blurred vision or eye movement disorders , as described and validated by the authors : it is unlikely , then , that the involvement of the ciliary ganglion is responsible for anisocoria . besides , even an accidental contact of the left eye with mepivacaine is unlikely to be the cause of this condition , as conjunctival administration of mepivacaine does not cause pupil dilation . despite hemodynamic stability in our patient , we examined anyway the possibility of an intracranial vascular event as the cause of unilateral mydriasis in the postoperative period . consequently , the patient 's pupil dilation could have been caused by accidental exposure to atropine , which entered the conjunctival sac and caused anisocoria . the photographic monitoring of anisocoria in the post - operative period , and the relative brevity of unilateral mydriasis , empirically confirmed the diagnosis and the benign prognosis . as reported , the authors point out that an accidental iatrogenic exposure to mydriatic agents should be considered as a possible cause of intraoperative unilateral mydriasis , in addition to the major causes that should be immediately investigated and then managed in the most effective way .
introduction . anisocoria indicates a difference in pupil diameter . 
 etiologies of this clinical manifestation usually include systemic causes as neurological or vascular disorders , and local causes as congenital iris disorders and pharmacological effects.case report . 
 we present a case of a 47-year - old man , suffering from spastic tetraparesis . 
 after the oral surgery under general anesthesia , the patient developed severe anisocoria : in particular , a ~4 mm diameter increase of the left pupil compared to the right pupil.we performed computed tomography ( ct ) in the emergency setting , nuclear magnetic resonance ( nmr ) of the brain and magnetic resonance angiography of intracranial vessels . 
 these instrumental examinations did not show vascular or neurological diseases . 
 the pupils returned to their physiological condition ( isocoria ) after about 180 minutes.discussion and conclusions . 
 literature shows that the cases of anisocoria reported during or after oral surgery are rare occurrences , especially in cases of simple tooth extraction . 
 anisocoria can manifest in more or less evident forms : therefore , it is clear that knowing this clinical condition is of crucial importance for a correct and timely resolution .