![]() ![]() The normal pupil varies in size, depending on the ambient illumination. If not, do they react to a near target?.Do the pupils react to a light stimulus?.Are the pupils round or irregularly shaped?.The mnemonic PERRLA (pupils equal, round, reactive to light, and accommodation)reminds us of the four questions we should ask in evaluating the pupils: Pupillary function is an important objective clinical sign in patients with visual loss and neurologic disease. Parasympathetic fibers for pupillary constriction leave the Edinger–Westphal nucleus and travel along the ipsilateral third cranial nerve to the ipsilateral ciliary ganglion within the orbit. The sympathetic fibers responsible for facial sweating and vasodilation branch off at the superior cervical ganglion from the remainder of the oculosympathetic pathway (explaining why patients with a third-order Horner syndrome usually do not have anhidrosis ).Īfferent pupillary fibers leave the optic tract before the lateral geniculate nucleus via the brachium of the superior colliculus to reach the pretectal nuclei (explaining why lesions of the geniculate nucleus, the optic radiations, or the visual cortex do not affect pupillary size or pupillary reactivity, and why lesions of the brachium of the superior colliculus can cause a relative afferent pupillary defect without visual loss). It then ascends to the superior cervical ganglion (located near the angle of the mandible and the bifurcation of the common carotid artery). Second-order neuron: travels from the sympathetic trunk, through the brachial plexus, and over the lung apex. Because the afferent pathways serving the light reflex and the near reflex are anatomically distinct, patients with severe optic neuropathies will still have intact, brisk pupillary responses to near stimuli, while their pupils will not, or will only poorly, react to light’ If a patient with a suspected optic neuropathy (regardless of the cause) has no RAPD, either the patient does not have an optic neuropathy or the optic neuropathy is bilateral. A relative afferent pupillary defect will not cause. Presence of a relative afferent pupillary defect (RAPD).Response to light (direct and consensual response).What is the ratio of postganglionic parasympathetic fibers that innervate the ciliary muscle to those that innervate the pupillary sphincter muscle? What is the course of the parasympathetic fibers for pupillary constriction from the Edinger-Westphal nucleus to the ciliary ganglion?ġ1. Why do lesions of the geniculate nucleus, the optic radiations, or the visual cortex not affect pupillary size or pupillary reactivity?ġ0. What is neurotransmitter is released at the neuromuscular junction of the iris sphincter to result in pupillary dilation?ĩ. What is neurotransmitter is released at the neuromuscular junction of the iris sphincter to result in pupillary constriction?Ĩ. Why do patients with a third-order Horner syndrome usually do not have anhidrosis?ħ. Which order neuron is involved when the Horner syndrome is caused by a tumor in the apex of a lung?Ħ. If a patient has a severe bilateral optic neuropathy will the pupils respond to near stimuli?ĥ. If a patient is suspected of having optic neuropathy (regardless of the cause) has no RAPD does that rule-out this diagnosis?Ĥ. When examining the pupils, what should you record?ģ.
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