Uncommon: intermittent pupillary mydriasis of young (some cases) If patient over 50: palpate temporal arteriesįull neurologic examination: if the patient has neurologic symptomsĭecreased visual acuity, color acuity or RAPD Relative afferent pupillary defect (RAPD)?Įyelids: ptosis? (possible partial third nerve palsy or Horner syndrome)ĭecreased corneal or facial sensation to light touch?Įxamine the neck (lumps or lymphadenopathy?)Įxamine the hands (clawing or finger abduction or adduction weakness?) Hemifacial, neck or arm pain? (possible Horner syndrome from ICA dissection)Īny clues to the cause anywhere in the body?ĭo both pupils constrict rapidly and fully to light? If not, do they constrict to near?ĭo both pupils dilate rapidly and fully in the dark? If patient over 50: symptoms of giant cell arteritis? car accident “whiplash” injury, chiropractic manipulation or roller-coaster ride? (possible Horner syndrome from ICA dissection) Previous ophthalmic history: eye trauma or surgery? (possible traumatic mydriasis)Īny neurologic symptoms: headache, numbness or weakness? How was the anisocoria first noticed: on a routine check or was the patient having visual or neurologic symptoms?īlurred vision or field loss? (possible orbital apex tumor)ĭiplopia? (possible partial third nerve palsy from aneurysm or tumor) Have you asked about, and looked for, all the following key features? Common causes for Horner syndrome include a tumor compressing any part of the chain in the head, neck or upper chest an internal carotid artery (ICA) dissecting aneurysm in the neck a presumed ischemic insult due to atherosclerosis or a congenital defect in the sympathetic chain Horner syndrome is caused by a lesion anywhere in the sympathetic chain which descends from the hypothalamus in the center of the brain down through the brainstem and cervical spinal cord, runs across the top of the lung, then ascends with the internal carotid artery upwards through the neck and then forwards through the cavernous sinus to reach the orbit. Sympathetic chain disease (brain, neck, upper chest) More commonly, ciliary ganglion disease of unknown cause results in the Holmes-Adie tonic pupil syndrome, which can be recognized by light-near dissociation, spiraling of the iris on slit-lamp examination and the absence of other neurologic symptoms or signs other than (sometimes) areflexia Third nerve disease can very rarely present with just a dilated pupil but almost always ptosis, motility disturbance or both signifies that a partial third nerve palsy is present. Parasympathetic chain disease (brain, third nerve, ciliary ganglion) Infrequently, the patient may have (purposefully or accidentally) instilled a dilating or constricting substance into the eye Previous blunt trauma can also cause persisting traumatic mydriasis. Overall, the most common cause of pathologic anisocoria seen by ophthalmologists is change in the iris itself, most often due to previous cataract or corneal surgery. In the neural pathway that causes pupil dilation (the sympathetic chain) In the neural pathway that causes pupil constriction (the parasympathetic chain) Pathologic anisocoria is due to disease in one of three places: Physiologic anisocoria can be recognized because the patient is asymptomatic, both pupils constrict briskly to light and dilate briskly to dark, there is no ptosis and ocular movements are normal.

Physiologic anisocoria is common: one in five normal subjects has a slight but noticeable difference in the size of their pupils. Horner syndrome).Īnisocoria can be physiologic or pathologic.

Holmes-Adie tonic pupil) or requires referral or investigation (e.g. On history and examination, we need to decide if the patient can be clinically diagnosed and reassured (e.g. Alternatively, you might notice anisocoria while examining the patient for another complaint.Īs ophthalmologists, we all need to have a practical plan for assessing patients with unequal pupils. Patients occasionally present because a difference in the sizes of their pupils has been noticed by their family, an examining practitioner or the patient themselves. Unequal pupils (anisocoria) may be caused by disease of the:

Causs of unequal pupil size