Normal pupil size mm8/18/2023 Pupillary dilation following ocular trauma often results from injury to the pupillary sphincter muscle. Ocular conditions that keep the large pupil from constricting (e.g., posterior synechia, angle closure glaucoma, previous ocular surgery, ocular trauma, pseudoexfoliation syndrome, and chronic mydriatic use) can produce mydriasis of various sizes the pupil is not or is poorly reactive to light. Indeed, the noncontrast head CT routinely ordered in the emergency room for a patient with mydriasis is useless and falsely reassuring. Investigations should be obtained only once the mechanism of mydriasis is understood. The clinical history and associated symptoms or signs, such as visual loss, diplopia, and ptosis, help in the diagnosis. When the larger pupil does not constrict as well as the small pupil in light, then the large pupil is abnormal (mydriasis). The evaluation of the patient with a third nerve palsy depends on associated symptoms and signs, the pattern of oculomotor nerve involvement, and the age of the patient.Īn isolated third nerve palsy with mydriasis may reveal an intracranial aneurysm or pituitary apoplexy, especially if associated with acute headache.Įxplanation: “ Mydriasis (the Large Pupil Is Abnormal) Because the pupillary fibers are located superficially, they are vulnerable to compressive processes such as aneurysmal mass effect, various tumors such as pituitary apoplexy, and uncal herniation. Pupil involvement is common in nuclear, fascicular, and subarachnoid third nerve palsies. Not all third nerve palsies have pupil involvement. Over time, tonic pupils tend to become smaller (“little old Adies”).Ī completely isolated mydriasis is extremely unlikely to be related to a third nerve palsy and should be evaluated clinically and with pharmacologic testing to rule out an Adie pupil or pharmacologic mydriasis prior to obtaining any further workup. What may happen to the size of the pupil over time in the Adie syndrome? Mydriasis from isolated third nerve palsy is essentially always associated with an extraocular movement deficit (responsible for diplopia) and/or ptosis.Ĩ. Is isolated mydriasis likely to be caused by a 3rd nerve paresis? The ratio of fibers that serve accommodation compared with pupil constriction is about 30:1, there is an overwhelming amount of regenerating accommodative fibers that respond to a near stimulus but may aberrantly regenerate to the pupil sphincter muscle.ħ. Patients often complain of blurry vision at near (accommodation paralysis) and sensitivity to light (from the large pupil).Slow tonic redilation of the pupil from near to distance because of sphincter muscle denervation supersensitivity.Better constriction when looking at a near target.Large pupil that does not react or reacts poorly to light.Therefore, third nerve palsies and tonic pupil (Adie pupil) from ciliary ganglion dysfunction may produce a mydriasis with a poorly or nonreactive pupil in response to light.Ĭlinical symptoms and signs of Adie tonic pupil include the following: What are two conditions that cause mydriasis via the parasympathetics? Parasympathetic fibers for pupillary constriction travel along the third cranial nerve to the ipsilateral ciliary ganglion within the orbit. If the dilated pupil constricts only partially or not at all, the diagnosis of pharmacologic mydriasis is confirmed.ģ. If there is no response after 45 minutes, place two drops of pilocarpine 1 or 2% in each eye. Place two drops of dilute pilocarpine (0.1%) in both eyes to make sure this is not atonic pupil (in which case, the dilated pupil will constrict because of denervation hypersensitivity, whereas the normal or pharmacologic pupil will not change).ī. Pharmacologic testing confirms the diagnosis of pharmacologic mydriasis:Ī. Ocular conditions that keep a large pupil from constricting include: posterior synechia, angle closure glaucoma, previous ocular surgery, ocular trauma, pseudoexfoliation syndrome, and chronic mydriatic use can produce mydriasis of various sizes the pupil is not or is poorly reactive to light. What diagnoses should we worry about for a patient with an isolated third nerve palsy with mydriasis? Do all 3rd nerve paresis have pupillary involvement?ġ1. Is complete mydriasis likely to be related to a 3rd nerve paresis?ġ0. Is isolated mydriasis likely to be caused by a 3rd nerve paresis?ĩ. What may happen to the size of the pupil over time in the Adie syndrome?Ĩ. What topical drop is used to confirm the presence of Adie pupil syndrome?ħ. What explains the light-near dissociation classically found in Adie tonic pupil syndrome.Ħ. What are the clinical symptoms and signs of Adie tonic pupilĥ. What are two conditions that cause mydriasis via the parasympathetics?Ĥ. How does one test for pharmacologic mydriasis from topical agents?ģ. What are ocular disorders that keep a large pupil from constricting?Ģ.
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