Cats unequal pupil size cataract6/12/2023 Anticholinergics such as atropine, homatropine, tropicamide, scopolamine, and cyclopentolate lead to mydriasis and cycloplegia by inhibiting parasympathetic M3 receptors of the pupillary sphincter and ciliary muscles. Pharmacologic anisocoria can present as mydriasis or miosis following administration of agents that act on the pupillary dilator or sphincter muscles. Causes include physical injury from ocular trauma or surgery, inflammatory conditions such as uveitis, angle closure glaucoma leading to iris occlusion of the trabecular meshwork, or intraocular tumors causing physical distortion of the iris. Mechanical anisocoria results from damage to the iris or its supporting structures. Examples include aniridia, coloboma, and ectopic pupil. Physiologic anisocoria may be intermittent, persistent, or even self-resolving.Ĭongenital anomalies in the structure of the iris may contribute to abnormal pupillary sizes and shapes that present in childhood. Light and near responses are intact, and the degree of anisocoria is typically equal in light and dark. The exact cause is unknown, but it is thought to be due to transient asymmetric supranuclear inhibition of the Edinger-Westphal nucleus that controls the pupillary sphincter. It is a benign condition with a difference in pupil size of less than or equal to 1 mm. Physiologic (also known as simple or essential) anisocoria is the most common cause of unequal pupil sizes, affecting up to 20% of the population. 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. Thus, thorough clinical evaluation is important for appropriate diagnosis and management of the underlying cause. It is relatively common, and causes vary from benign physiologic anisocoria to potentially life-threatening emergencies. © 2019 Neuro-ophthalmology Virtual Education Library: NOVEL Īnisocoria indicates unequal pupil sizes. If your pet is not improving, and/or there is development of additional clinical signs, contact your veterinarian.Anisocoria.Administer any prescribed medication as directed by your veterinarian.Antibiotics and/or anti-inflammatory drugs may be recommended for certain bacterial or inflammatory disorders.No treatment may be needed in disorders such as iris atrophy or hypoplasia, in which the iris is underdeveloped or decreased in size.Your veterinarian might recommend several treatments while results regarding an underlying disorder are pending. It is difficult to treat patients with anisocoria symptomatically, as there can be multiple underlying causes that are treated in very specific ways. Treatment of Anisocoria (unequal pupil sizes) in Cats ![]() Computed tomography (CT) scan or magnetic resonance imaging (MRI).Visual evoked potential (VEP) to evaluate optic nerve and brain function.Electroretinography (ERG) to evaluate retinal function. ![]() ![]()
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