The use of eye drops is a common cause of a harmless change in pupil size. An injury or lesion in either pathway may result in changes in pupil size. Generally, anisocoria is caused by impaired dilation (a sympathetic response) or impaired constriction (a parasympathetic response) of pupils. Postganglionic fibers of the short ciliary nerve reach the pupillary sphincter and ciliary muscles. The Edinger-Westphal nucleus then supplies parasympathetic fibers to the third cranial nerve which traverses the cavernous sinus and enters the orbit via the superior orbital fissure to synapse at the ipsilateral ciliary ganglion. The second-order neuron connects each pretectal nucleus to bilateral Edinger-Westphal nuclei in the midbrain and allows for the consensual light reflex.
Afferent light stimulus is received by retinal ganglion cells whose axons traverse as the optic nerve, optic chiasm and optic tract that eventually synapses at the pretectal nuclei of the dorsal midbrain at the level of the superior colliculi. The parasympathetic pathway is a four-order neuron pathway that controls pupillary constriction and accommodation. Sudomotor fibers course with the external carotid artery to innervate sweat glands of the face. The third-order neuron ascends along the carotid artery into the cavernous sinus to ultimately synapse at the pupillary dilator muscle, the Muller muscle of the upper eyelid, and the smooth muscle of the lower eyelid. The second-order neuron continues over the lung apex and synapses at the superior cervical ganglion located at the carotid bifurcation. The first-order neuron originates from the posterolateral hypothalamus and travels caudally down the brainstem to the ciliospinal center of Budge (C8-T2). The sympathetic pathway is a three-order neuron pathway that mediates pupillary dilation. Pupillary function is autonomic, largely occurring in response to light stimulation and adrenergic tone. Physiologic control of pupillary function is dictated by sympathetic and parasympathetic innervation to the pupillary dilator and the pupillary sphincter muscles, respectively. If you have differing pupil size after an eye or head injury, get medical help immediately.Īlways seek immediate medical attention if differing pupil size occurs along with:.The new development of different-sized pupils may be a sign of a very serious condition. You should see a health care provider if you have sudden changes that result in unequal pupil size.Ĭontact a doctor if you have persistent, unexplained, or sudden changes in pupil size. Treatment depends on the cause of the unequal pupil size. Pupils that respond more to accommodation than light.Anhidrosis (reduced sweating on the face of the affected side).Red flags – The following findings are of particular concern: Serious disorders should be considered in patients with Horner syndrome or 3rd cranial nerve palsy.
#UNEQUAL PUPIL SIZE WHY LICENSE#
Many disorders are accompanied by anisocoria due to iris or neurologic dysfunction but usually manifest with other, more bothersome symptoms (e.g., uveitis, stroke, subarachnoid hemorrhage, acute angle-closure glaucoma).Įxamining the pupils in light and dark and inspecting an old photograph or the driver’s license of the patient provide a great deal of diagnostic information. Unequal pupil sizes of more than 1 mm that develop later in life and do NOT return to equal size may be a sign of an eye, brain, blood vessel, or nerve disease. If there are no other symptoms and if the pupils return to normal, then it is nothing to worry about.
If other family members also have similar pupils, then the pupil size difference could be genetic and is nothing to worry about.Īlso, for unknown reasons, pupils may temporarily differ in size. The difference between pupil sizes in physiologic anisocoria is typically ≤ about 1 mm.īabies born with anisocoria (different sized pupils) may not have any underlying disorder. Most often, the diameter difference is less than 0.5 mm, but it can be up to 1 mm (0.05 inch). Physiologic anisocoria: slight differences in pupil sizes are found in up to 1 in 5 healthy people. Therefore thorough clinical evaluation is important for the appropriate diagnosis and management of the underlying cause. Anisocoria is a relatively common condition, and causes vary from benign physiologic anisocoria to potentially life-threatening emergencies. It gets larger in dim light and smaller in bright light. The pupil is the black part in the center of the eye. Anisocoria is a condition characterized by unequal pupil sizes 1).