12/14/2023 0 Comments Miotic pupil oculomotor5 It is this bilateral innervation of the Edinger-Westphal nucleus that results in both direct and consensual responses to light shone in one eye. 2 Information from the optic nerve passes to the ipsilateral pretectal nucleus and then on to the Edinger-Westphal nuclei on both sides. The pupillary light response involves both afferent (optic nerve) and efferent (oculomotor nerve and sympathetic) pathways. Examination should include assessment of visual acuity, visual fields to confrontation, pupil testing, extraocular motility and whether or not ptosis is present. 5 It is important to ask about previous or current malignancies and neck trauma. Associated visual and/or neurological symptoms should be sought, including visual blurring, visual loss, disturbance of visual fields, or diplopia. 2,5Ī thorough history should include asking about the use of new medications or inadvertent ocular contact with foreign substances by rubbing the eyes. 2–4 Non-physiological anisocoria indicates disease of the sympathetic or parasympathetic pathways supplying the pupil, or a problem with the iris itself. Physiological anisocoria is common: approximately 20% of normal people have different-sized pupils. 1 This article aims to guide management in both of these situations. Indeed, new onset anisocoria may be an early sign of a life-threatening emergency. The general practitioner (GP) may discover anisocoria during examination for a seemingly unrelated problem. The aetiology may be physiological, pathological or pharmacological. However, there are no eyelid or movement abnormalities.A difference in pupil size between the eyes is known as anisocoria. Balcer explained, and in the early course patients may complain of accommodative insufficiency or glare. However, they exhibit light-near dissociation, Dr. Tonic pupilsPatients with tonic pupils often notice one large or irregular pupil, which tends to become miotic when the condition is chronic. "When a patient with aberrant regeneration of the third nerve presents, the ophthalmologist should think of compressive lesions, most often aneurysms or tumors," she emphasized. Balcer demonstrated.Ĭompressive lesions and trauma are the most common causes of aberrant regeneration of the third nerve. The pupil did not react to consensual light stimulation however, upon adduction the pupil became more miotic than that of the left eye, Dr. This recovered into a partial pupil involving third nerve palsy. She described a patient with pituitary apoplexy who had complete ophthalmoplegia of the right eye. As they regrow, they reach the ciliary ganglion and result in miosis when the patient adducts the eye, according to Dr. Many different types of this pathology have been identified, but in the case of light-near dissociation, the fibers that used to innervate the medial or inferior rectus muscle of the third nerve are damaged. She described a patient with Argyll-Robertson pupils who was shown to have pupils that did not respond well to light but contracted to near.Īberrant regenerationWhen patients present with unilateral light-near dissociation, eye movement abnormalities, or signs of a third nerve palsy, there may be aberrant regeneration. This also spares the supranuclear fibers that subserve the pupillary near response," she said. "The lesion is thought to occur within the interneurons that connect the pretectal nuclei and the Edinger-Westphal nuclei in the midbrain. Unlike the pupils of dorsal midbrain syndrome, Argyll-Robertson pupils also may be irregular and dilate poorly in the dark. Balcer noted that Argyll-Robertson pupils, which are miotic, are classically associated with neurosyphilis. Midbrain abnormalities that cause light-near dissociation are often bilateral, but they can be unilateral or asymmetric.Īrgyll-Robertson pupilsArgyll-Robertson pupils are another prominent cause of bilateral pupillary light-near dissociation. The pupils in the dorsal midbrain syndrome are midposition or large," she said. "The most common lesions in this case are those caused by hydrocephalus, stroke, or tumor. The result is pupillary light-near dissociation," she said. A lesion in this region spares the supranuclear fibers that descend directly toward the ocular motor nerve complex. "The lesion in these patients is located in the pretectal nuclei and ganglion cell axons as they enter the midbrain. Balcer, as well as upgaze paresis, convergence retraction nystag- mus, and eyelid retraction. Dorsal midbrain syndromeIn patients with dorsal midbrain syndrome, light-near dissociation is a prominent feature, according to Dr.
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