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Mydriasis

Mydriasis refers to the dilation of the pupil, the central opening in the iris of the eye that regulates the amount of light entering the retina.^[1] In physiological terms, mydriasis occurs naturally in low-light conditions to allow more light for better vision, mediated by the sympathetic nervous system's activation of the dilator pupillae muscle and inhibition of the parasympathetic constrictor mechanism.^[2] Pathological mydriasis, however, involves excessive or fixed pupil dilation that is unresponsive to light changes, often signaling underlying dysfunction in the ocular or neurological pathways.^[3] Common causes of mydriasis include pharmacological agents, such as mydriatic eye drops used in eye examinations or systemic anticholinergic medications that block parasympathetic signals to the sphincter pupillae muscle.^[4] Trauma to the eye or head can damage the iris musculature or cranial nerves, leading to unilateral dilation, while neurological conditions like oculomotor nerve (third cranial nerve) palsy disrupt parasympathetic innervation, resulting in a dilated, non-reactive pupil.^[5] Other triggers encompass drug use (e.g., stimulants like cocaine or amphetamines that enhance sympathetic activity), increased intracranial pressure from brain injury or tumors, and benign episodic unilateral mydriasis associated with migraines.^[6] Adie's tonic pupil, a form of internal ophthalmoplegia, presents with sluggish or tonic dilation due to postganglionic parasympathetic denervation.^[7] Mydriasis may be asymptomatic or accompanied by blurred vision, light sensitivity (photophobia), or headaches, depending on the etiology, and it can increase the risk of angle-closure glaucoma in susceptible individuals by shallowing the anterior chamber.^[1] Diagnosis typically involves pupillary light reflex testing, slit-lamp examination, and pharmacological tests (e.g., pilocarpine to assess parasympathetic function), with imaging or neurological consultation if systemic causes are suspected.^[8] Treatment targets the underlying cause: discontinuation of offending drugs, surgical intervention for trauma, or supportive care for benign cases, though urgent evaluation is essential to rule out life-threatening conditions like brainstem herniation.^[9]

Physiology

Normal Pupil Regulation

The pupil size is regulated by the antagonistic actions of two smooth muscles in the iris: the sphincter pupillae muscle, which encircles the pupil and contracts to cause constriction (miosis), and the dilator pupillae muscle, which radiates outward from the pupil and contracts to cause dilation (mydriasis).^[10] The sphincter pupillae is innervated by parasympathetic fibers, while the dilator pupillae receives sympathetic innervation.^[11] This balanced opposition maintains normal pupil diameter between approximately 2 and 4 mm in bright light and 4 to 8 mm in dim conditions, optimizing retinal illumination and visual acuity.^[12] Neural control of pupil size involves distinct parasympathetic and sympathetic pathways. The parasympathetic pathway originates in the Edinger-Westphal nucleus of the oculomotor complex (cranial nerve III), sending preganglionic fibers via the oculomotor nerve to the ciliary ganglion; postganglionic fibers then travel through short ciliary nerves to innervate the sphincter pupillae, promoting constriction.^[13] In contrast, the sympathetic pathway begins in the hypothalamus, descends through the brainstem and spinal cord to preganglionic neurons in the intermediolateral cell column at T1-T2 levels, synapses in the superior cervical ganglion, and sends postganglionic fibers via the nasociliary nerve and long ciliary nerves to the dilator pupillae, facilitating dilation.^[2] These pathways ensure dynamic adjustment to environmental and internal stimuli, with parasympathetic dominance in lighted conditions and sympathetic influence prevailing in darkness.^[14] The pupillary light reflex exemplifies normal regulation, constricting the pupils in response to increased light intensity to protect the retina and enhance depth of focus. The afferent limb transmits signals from retinal ganglion cells via the optic nerve (cranial nerve II) to the pretectal olivary nucleus in the midbrain, which projects bilaterally to the Edinger-Westphal nuclei.^[13] The efferent limb then activates parasympathetic outflow from the Edinger-Westphal nucleus through the oculomotor nerve to the ciliary ganglion and sphincter pupillae, resulting in consensual miosis in both eyes.^[15] This reflex operates rapidly, with constriction onset within 200-300 milliseconds.^[16] Beyond light, pupil dynamics respond to accommodation and emotional states. During the near reflex, parasympathetic activation via the Edinger-Westphal nucleus constricts the pupil (accommodative miosis) to improve focus on close objects, coordinating with ciliary muscle contraction for lens thickening and medial rectus contraction for convergence.^[17] Emotional arousal or cognitive effort, such as surprise or mental concentration, triggers sympathetic-mediated dilation to increase light intake and signal heightened alertness, often overriding light-induced constriction.^[18] These responses maintain adaptive visual function across varied contexts.^[19]

Mechanisms of Mydriasis

Physiological mydriasis results from the balanced autonomic control of the iris muscles, involving sympathetic stimulation of the dilator pupillae and withdrawal of parasympathetic tone on the sphincter pupillae, leading to pupil dilation in response to low light or arousal.^[2] Sympathetic activation drives mydriasis by stimulating the radial dilator pupillae muscle of the iris. Postganglionic sympathetic fibers release norepinephrine, which binds to alpha-1 adrenergic receptors on the dilator muscle, triggering contraction via a G protein-coupled signaling cascade involving phospholipase C and inositol trisphosphate, resulting in increased pupil diameter to allow greater light entry.^[20]^[14] Parasympathetic inhibition contributes to mydriasis by reducing the constrictive tone on the circular sphincter pupillae muscle. This occurs through decreased acetylcholine release from postganglionic parasympathetic fibers in low-light conditions, allowing unopposed sympathetic activity to predominate and promote dilation.^[21]^[14]

Causes

Physiological Causes

Physiological mydriasis refers to the normal, transient dilation of the pupils in response to environmental or internal stimuli, serving adaptive functions without indicating underlying disease. One primary trigger is exposure to low light conditions, where the pupils dilate to allow more light to enter the eye and reach the retina, enhancing visual acuity in dim environments.^[2] In low light, reduced illumination leads to decreased parasympathetic activity, resulting in unopposed sympathetic tone that contracts the iris dilator muscle.^[22] Emotional arousal also induces mydriasis through activation of the sympathetic nervous system, often triggered by adrenaline surges during states of fear, excitement, or pain.^[2] This dilation correlates reliably with heightened autonomic arousal, enabling pupillometry as a tool to study emotional states in psychological research.^[23] Similarly, sexual arousal can cause pupil dilation, influenced by hormones such as oxytocin, which enhances sensitivity to social and emotional cues and amplifies stimulus-induced pupillary responses.^[24]^[25] A specific physiological phenomenon is benign episodic unilateral mydriasis (BEUM), characterized by transient, self-limited episodes of unilateral pupil dilation without associated neurological deficits or underlying pathology.^[26] These episodes, often lasting minutes to hours, are idiopathic and may involve transient sympathetic hyperactivity, typically resolving spontaneously and recurring infrequently.^[27] BEUM is a diagnosis of exclusion, distinguished from pathological causes by its benign course and absence of persistent symptoms.^[28]

Pharmacological Causes

Pharmacological causes of mydriasis arise from exogenous substances that disrupt the autonomic nervous system's balance in pupil regulation, primarily by inhibiting parasympathetic activity or stimulating sympathetic pathways.^[2] These agents include prescription medications, over-the-counter drugs, recreational substances, and toxins, often leading to reversible pupil dilation depending on dose and exposure duration.^[29] Anticholinergic drugs, such as atropine and scopolamine, induce mydriasis by competitively antagonizing muscarinic acetylcholine receptors in the iris sphincter muscle, thereby blocking parasympathetic-mediated pupil constriction.^[30] Atropine, derived from belladonna alkaloids, is commonly used in ophthalmology for cycloplegia and mydriasis during eye examinations, with effects lasting up to 7-10 days after topical application.^[31] Scopolamine, similarly, causes pupillary dilation through antimuscarinic action and is employed in transdermal patches for motion sickness, though inadvertent ocular contact can result in unilateral or bilateral mydriasis.^[32] These agents exemplify how inhibition of the parasympathetic system, as briefly referenced in pupil regulation mechanisms, promotes unopposed sympathetic tone.^[33] Sympathomimetic agents like amphetamines and cocaine promote mydriasis by enhancing norepinephrine release or inhibiting its reuptake at sympathetic nerve endings, leading to contraction of the iris dilator muscle.^[34] Amphetamines, including methamphetamine, stimulate alpha- and beta-adrenergic receptors, producing dilated pupils as part of a broader sympathomimetic response that may include tachycardia and hypertension.^[35] Cocaine specifically blocks the norepinephrine transporter, causing rapid pupillary dilation observable within minutes of use, which serves as a clinical sign of intoxication.^[2] Chronic exposure to these substances can exacerbate ocular effects, though mydriasis typically resolves with discontinuation.^[36] Certain recreational drugs, including MDMA (3,4-methylenedioxymethamphetamine) and LSD (lysergic acid diethylamide), contribute to mydriasis through serotonin-mediated pathways intertwined with sympathetic activation. MDMA induces pupil dilation by releasing serotonin, dopamine, and norepinephrine, with studies showing increases in pupil diameter up to 4 mm peaking 1-2 hours post-ingestion, often accompanied by hyperthermia and autonomic arousal.^[37] LSD, a potent 5-HT2A receptor agonist, causes mydriasis via central serotonergic stimulation, resulting in dilated pupils and nystagmus as early signs of intoxication, with effects linked to its hallucinogenic profile.^[38] These drugs highlight the role of monoamine modulation in altering pupillary responses beyond direct adrenergic effects.^[39] Iatrogenic mydriasis frequently occurs from therapeutic interventions, such as topical eye drops containing tropicamide, a short-acting cycloplegic agent used for diagnostic pupillary dilation in routine ophthalmic exams, with effects onset in 20-40 minutes and duration of 4-6 hours.^[33] Systemically, tricyclic antidepressants (e.g., amitriptyline) and first-generation antihistamines (e.g., diphenhydramine) can cause mydriasis due to their anticholinergic side effects, leading to blurred vision and increased intraocular pressure risk in susceptible individuals.^[40] Antihistamines block histamine H1 receptors but also exhibit antimuscarinic activity, resulting in pupillary dilation, dry mouth, and potential delirium in overdose scenarios.^[41] These unintended effects underscore the need for monitoring in patients with narrow-angle glaucoma predisposition.^[29]

Pathological Causes

Pathological causes of mydriasis arise from structural damage, neurological disruption, or disease processes that impair the normal regulatory mechanisms of pupil dilation, often leading to persistent or fixed pupillary enlargement.^[5] Trauma represents a primary pathological etiology, where direct injury to the iris or surrounding structures disrupts pupillary function. Ocular trauma, such as blunt force or penetrating injuries, can damage the iris sphincter muscle, resulting in traumatic mydriasis characterized by a dilated, irregular pupil that fails to constrict properly due to tears or scarring in the iris tissue.^[42] Head trauma, including traumatic brain injury (TBI), may indirectly cause mydriasis through compression or damage to the oculomotor nerve (third cranial nerve), leading to unilateral or bilateral fixed dilation; in severe cases, such as those involving brainstem involvement, this can persist as a sign of irreversible damage.^[43]^[5] Autonomic neuropathy contributes to mydriasis by denervating the parasympathetic pathways that control pupillary constriction. In Adie's syndrome, a form of idiopathic autonomic dysfunction, parasympathetic denervation of the ciliary ganglion results in a tonic pupil that is abnormally dilated, with sluggish or absent response to light, often affecting one eye and accompanied by absent deep tendon reflexes.^[44] Diabetic autonomic neuropathy, a common complication of long-standing diabetes mellitus, impairs both sympathetic and parasympathetic innervation to the pupil; parasympathetic dysfunction specifically leads to relative mydriasis under light conditions due to reduced constrictor tone, while sympathetic involvement may exacerbate dilation in darkness.^[45]^[46]^[47] Neurological disorders can induce mydriasis through central or peripheral nervous system involvement that overrides or damages pupillary control centers. Oculomotor nerve palsy disrupts parasympathetic innervation to the iris sphincter muscle, resulting in a dilated, non-reactive pupil, often accompanied by ptosis and extraocular muscle weakness.^[5] Brain herniation, often due to increased intracranial pressure from conditions like hemorrhage or edema, compresses the oculomotor nerve, producing a fixed dilated pupil as a critical component of Cushing's triad (alongside hypertension and bradycardia), signaling impending brainstem failure.^[48] Migraine headaches, particularly those with autonomic features, may cause transient unilateral mydriasis via episodic parasympathetic inhibition or ciliary ganglion dysfunction, resolving with the attack but recurring in susceptible individuals.^[27] Ocular diseases lead to mydriasis primarily through iris structural compromise or inflammatory processes that weaken constrictor function. Acute angle-closure glaucoma triggers an acute rise in intraocular pressure, which can cause iris sphincter ischemia and subsequent atrophy, resulting in a fixed mid-dilated pupil after the episode due to permanent damage to the iris musculature.^[49] Iris atrophy, seen in conditions like essential iris atrophy (part of iridocorneal endothelial syndrome), progressively thins and scars the iris stroma and sphincter, preventing normal constriction and leading to chronic mydriasis that may be unilateral and associated with secondary glaucoma.^[50]^[51]

Clinical Presentation

Signs

Mydriasis is characterized by abnormal dilation of the pupil, typically exceeding 5 mm in diameter, often observed in ambient lighting conditions where normal pupils would constrict.^[52] This dilation is frequently fixed, meaning the pupil shows little to no constriction in response to direct or consensual light stimulation, distinguishing it from physiological pupillary responses.^[3]^[12] The condition may present unilaterally or bilaterally, with unilateral mydriasis resulting in anisocoria, where the affected pupil is markedly larger than the contralateral one, creating an asymmetry greater than the normal physiological variation of less than 1 mm.^[5]^[53] In cases involving a tonic pupil, such as in Adie syndrome, the dilated pupil exhibits a sluggish or vermiform constriction during accommodation (near response), though light reactivity remains poor or absent; over time, the accommodation response may weaken further.^[54]^[12] The duration of mydriasis can vary, manifesting as transient episodes lasting minutes to hours or as persistent dilation enduring days to indefinitely, observable through serial pupillary examinations.^[28]^[26]

Associated Symptoms

Mydriasis is frequently accompanied by visual disturbances that arise from altered light entry into the eye due to pupil dilation. Blurred vision occurs as the dilated pupil reduces the eye's depth of field, impairing focus on near objects, particularly in low-light conditions. Photophobia, or increased sensitivity to light, is common and results from excessive light overwhelming the retina, often exacerbating discomfort during episodes. Patients may also perceive halos around lights, especially in cases linked to corneal edema or elevated intraocular pressure.^[3]^[26]^[55] Headache and ocular pain often co-occur with mydriasis, varying in intensity based on the etiology. In migraine-associated mydriasis, such as benign episodic unilateral mydriasis, mild to severe headaches are reported, sometimes with orbital pain and photosensitivity during attacks. Acute angle-closure glaucoma presents with sudden, severe eye pain radiating to the brow or temple, accompanied by frontal headache due to rapid intraocular pressure elevation. Traumatic causes, like iris sphincter injury from blunt ocular trauma, can lead to localized pain and tenderness around the affected eye.^[27]^[55]^[56] Neurological symptoms may manifest alongside mydriasis in cases involving central or peripheral nervous system involvement. Brain injuries leading to uncal herniation often feature confusion, nausea, and vomiting as signs of increased intracranial pressure, with the fixed dilated pupil indicating third nerve compression. In peripheral neuropathies, such as autoimmune autonomic ganglionopathy, autonomic dysfunction can cause dry mouth and eyes secondary to parasympathetic impairment, contributing to tonic pupillary dilation.^[57]^[48]^[58] Systemic effects are prominent in severe pathological scenarios, such as brain herniation or widespread autonomic failure. Altered mental status, ranging from drowsiness to coma, accompanies bilateral mydriasis in transtentorial herniation, signaling critical brainstem compromise. Fever may arise in infectious or inflammatory processes underlying mydriasis, though it is less specific and often tied to the primary condition.^[57]^[48]^[59]

Diagnosis

Physical Examination

The physical examination for mydriasis begins with an initial observation of the pupils in ambient light to note size, symmetry, and shape, typically measuring diameter in millimeters using a handheld ruler or pupillometer while the patient fixates on a distant target.^[12]^[60] Direct ophthalmoscopy is performed by positioning the examiner 1-2 cm from the patient's eye, aligning the ophthalmoscope's light beam through the pupil to estimate size and observe the direct pupillary light reflex; the patient is instructed to fixate on a distant object, and the light is shone into the pupil to assess constriction in both the illuminated eye and the contralateral eye for consensual response.^[61]^[12] The swinging flashlight test is conducted in a dimly lit room using a bright penlight; the light is directed into one pupil for 2-3 seconds to observe constriction, then quickly swung to the other pupil while maintaining continuous illumination, repeating several cycles to detect any paradoxical dilation indicating a relative afferent pupillary defect.^[62] Slit-lamp biomicroscopy involves seating the patient at the slit-lamp apparatus, adjusting the illumination to a narrow beam at 45-60 degrees, and systematically examining the iris for tears, transillumination defects, or adhesions, followed by evaluation of the anterior chamber depth and clarity using the optical section technique to identify any hyphema, flare, or cells.^[63]^[64] Pharmacological testing is often employed to differentiate causes of mydriasis. For example, the dilute pilocarpine test uses 0.125% pilocarpine drops instilled in both eyes; in normal pupils or pharmacologic mydriasis, there is minimal constriction, whereas in parasympathetic denervation (e.g., Adie pupil or third nerve palsy), the affected pupil constricts significantly due to denervation supersensitivity. The test is performed after ensuring no recent exposure to miotic agents, with responses observed after 30-45 minutes.^[65] Neurological evaluation includes inspection for ptosis or lid lag, assessment of extraocular movements by having the patient follow a target in the six cardinal directions of gaze to check for limitations in adduction, elevation, or depression suggestive of third nerve involvement, and assessment for anhidrosis using specialized tests such as the starch-iodine test while observing for any contralateral pupillary constriction that might indicate sympathetic pathway disruption.^[66]^[67]

Differential Diagnosis

The differential diagnosis of mydriasis involves distinguishing it from conditions presenting with similar pupillary changes, such as anisocoria, fixed pupils, or episodic dilation, to identify underlying etiologies ranging from benign to life-threatening.^[68] Key considerations include the laterality (unilateral versus bilateral), reactivity to light, associated symptoms like pain or neurological deficits, and patient history, which help rule out mimics. In cases of anisocoria, mydriasis must be differentiated from miosis-related conditions like Horner syndrome, where the affected pupil is constricted due to sympathetic denervation, resulting in a smaller pupil that dilates sluggishly in the dark compared to the normal eye.^[69] Conversely, mydriasis features an abnormally dilated pupil that fails to constrict appropriately to light, often indicating parasympathetic dysfunction or pharmacologic blockade; testing with dilute pilocarpine can confirm parasympathetic integrity in Horner (constriction) versus absent response in mydriatic causes. Fixed dilated pupils raise concern for severe neurological events, such as brain death, characterized by bilateral nonreactive mydriasis alongside absent brainstem reflexes and coma, which contrasts with reversible pharmacologic mydriasis from agents like atropine that may show history of exposure and potential recovery with time or antidote.^[70] In brain death, pupils remain fixed despite interventions, whereas pharmacologic causes often spare other cranial nerves and respond to supportive care.^[71] Unilateral mydriasis requires differentiation from Adie's tonic pupil, a benign parasympathetic denervation causing a dilated, poorly reactive pupil to light but with preserved accommodation and slow redilation after constriction, typically in young women without pain or systemic symptoms.^[8] This differs from bilateral mydriasis due to systemic drug effects, such as anticholinergics, where both pupils are equally affected and reactivity is symmetrically impaired.^[3] Emergent conditions like angle-closure glaucoma present with painful unilateral mydriasis, elevated intraocular pressure, corneal edema, and halos around lights, necessitating urgent tonometry and gonioscopy to distinguish from benign episodic mydriasis, which is painless, transient, and self-resolving without visual acuity loss or inflammation.^[26] Benign episodic mydriasis is a diagnosis of exclusion after neuroimaging and ocular exam rule out herniation, trauma, or ischemia.^[72]

Management

Treatment Approaches

Treatment of mydriasis is tailored to the underlying etiology, aiming to reverse dilation where possible or mitigate symptoms while addressing the root cause. For pharmacologically induced mydriasis, particularly from anticholinergic agents, topical miotics such as pilocarpine eye drops can be administered to stimulate the iris sphincter muscle and promote pupillary constriction, though efficacy varies with the specific agent and may be limited in cases of strong cycloplegics like atropine.^[73] More recently, phentolamine ophthalmic solution (Ryzumvi), approved by the FDA in 2023, provides rapid reversal of mydriasis induced by adrenergic agonists or antimuscarinic drugs by blocking alpha-adrenergic receptors in the iris dilator muscle, reducing post-procedure light sensitivity.^[74] Cause-specific interventions are essential for pathological mydriasis. In traumatic cases, where iris sphincter tears lead to persistent dilation, surgical options such as pupilloplasty or cerclage techniques repair the damaged muscle, often combined with iris suturing to restore pupil shape and function.^[75] For mydriasis associated with diabetic autonomic neuropathy, optimizing glycemic control through insulin therapy, oral antidiabetics, and lifestyle modifications helps stabilize autonomic function and indirectly improves pupillary responses over time.^[76] For Adie's tonic pupil, management is typically supportive; low-dose pilocarpine eye drops may be used to constrict the pupil and alleviate symptoms like blurred vision, while bifocal glasses address accommodative issues, and sunglasses reduce photophobia.^[77] In migraine-related benign episodic unilateral mydriasis, standard migraine abortive therapies, including triptans or nonsteroidal anti-inflammatory drugs, alleviate the associated headache and resolve the transient dilation.^[26] Supportive measures play a key role in managing symptoms across etiologies. Patients are advised to wear tinted or polarized sunglasses to alleviate photophobia, and to avoid further exposure to mydriatic agents or environments with bright light until resolution.^[3] In emergency settings, such as uncal herniation causing fixed mydriasis due to elevated intracranial pressure, immediate interventions include head elevation to 30 degrees, osmotic therapy with mannitol or hypertonic saline, and hyperventilation to reduce pressure, followed by neurosurgical consultation.^[78]

Prognosis

In benign cases, such as physiological mydriasis triggered by low light or emotional responses, the condition typically resolves spontaneously without intervention, often within minutes to hours as environmental stimuli normalize.^[3] Similarly, pharmacologic mydriasis induced by agents like tropicamide generally achieves full resolution in 4 to 8 hours, while stronger agents like atropine may take 7 to 14 days for pupillary function to return to baseline.^[79]^[80] Benign episodic mydriasis, a physiological variant, carries a favorable prognosis with episodes self-limiting and no long-term neurological sequelae after ruling out serious causes.^[26] Pathological mydriasis outcomes vary by etiology; iris trauma often results in permanent dilation due to irreversible sphincter muscle damage, leading to persistent anisocoria and potential glare sensitivity unless surgically corrected.^[81]^[82] In neuropathies, prognosis is variable and treatment-dependent: benign forms resolve fully, but severe cases like those from oculomotor nerve compression may improve with addressing the underlying issue, though fixed dilation can persist.^[26] Untreated pathological mydriasis carries significant risks, including irreversible vision loss from elevated intraocular pressure in acute angle-closure glaucoma and very high mortality rates in cases of unaddressed brain herniation with fixed dilated pupils.^[55]^[48] Prognosis is influenced by patient-specific factors, including advanced age, which correlates with slower pupillary recovery and higher complication rates in both ocular and neurological etiologies, as well as comorbidities like diabetes that impair tissue healing.^[83]^[84] Prompt diagnosis and intervention are critical, particularly in pathological cases, where early management can prevent progression to permanent damage or life-threatening complications.^[85]

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Cocaine causes dilated pupils because of inhibition of reuptake of norepinephrine. In high concentrations, it may cause cycloplegia, and in chronic users, ...
[39]
Sympathomimetic Toxicity - StatPearls - NCBI Bookshelf - NIH
Feb 16, 2025 · While the primary mechanism of action of cocaine is reuptake inhibition, amphetamines have multiple mechanisms of action, including reuptake ...
[40]
Ocular manifestations of drug and alcohol abuse - PubMed Central
Use of opiates, both legally and illicitly, leads to pupillary miosis.[5**] Cocaine's inhibition of reuptake of norepinephrine causes pupillary mydriasis ...
[41]
Physiological and Subjective Responses to Controlled Oral MDMA ...
MDMA significantly increased pupil diameter 1.25 h post-dose (Tables 1 and 2), with diameters increased by up to 4 mm. High-dose MDMA significantly increased ...
[42]
Lysergic Acid Diethylamide Toxicity - StatPearls - NCBI Bookshelf
Dec 17, 2023 · General: altered mental status, diaphoresis, disheveled appearance, loss of appetite. HEENT: mydriasis, xerostomia, nystagmus. Respiratory: ...
[43]
The Pharmacology of Lysergic Acid Diethylamide: A Review - PMC
Dosing of animals (rats and cats) with very high doses of LSD (up to 100 μg/kg i.v.) leads to mild autonomic changes of mydriasis, tachycardia, tachypnea, ...
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A Review of Ocular Complications Associated with Medications ...
Feb 24, 2022 · Mydriasis is a common ocular side effect of the tricyclic antidepressants owing to their anticholinergic properties resulting in pupil dilation ...Missing: antihistamines | Show results with:antihistamines
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Antihistamine Toxicity - StatPearls - NCBI Bookshelf - NIH
Apr 29, 2023 · ... mydriasis causing blurred vision, hallucination, delirium, and ... Antihistamines are commonly found in many over-the-counter medications.
[46]
Resolution of traumatic mydriasis and accommodative dysfunction ...
Apr 21, 2022 · Traumatic mydriasis (TM) is caused by damage to the sphincter pupillae muscle, often with concomitant iris tears and irregular pupil shape.
[47]
Lasting bilateral mydriasis after traumatic brain injury may not ... - NIH
Sep 26, 2017 · Lasting bilateral mydriasis and absence of pupillary light reflex following severe traumatic brain injury (TBI) are considered signs of irreversible brainstem ...
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Adie Pupil - EyeWiki
May 12, 2025 · Adie tonic pupil (Adie syndrome or Holmes-Adie syndrome) is a disorder in which there is parasympathetic denervation of the afflicted pupil ...
[49]
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In most cases, the cause is unknown (idiopathic), but Adie syndrome can occur due to other conditions such as trauma, surgery, lack of blood flow (ischemia) or ...
[50]
Pupillary Abnormalities with Varying Severity of Diabetic Retinopathy
Apr 4, 2018 · Dysfunction of the PNS causes relative mydriasis in light conditions and diminished constriction to light. Dysfunction of the SNS causes ...
[51]
Pupil findings in a consecutive series of 150 patients with ...
Reduced pupil diameters in darkness and the redilatation lag were taken as indicators of sympathetic dysfunction, and reduced light reflexes or mydriasis in the ...
[52]
Brain Herniation - StatPearls - NCBI Bookshelf
Aug 13, 2023 · Patients may exhibit characteristic triple components of Cushing triad ... fixed dilated pupils and respiratory arrest owing to compression of the ...
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Chronic Paroxysmal Hemicrania - StatPearls - NCBI Bookshelf - NIH
Chronic paroxysmal hemicrania is a primary headache syndrome characterized by recurrent unilateral episodes of headache associated with cranial autonomic ...
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Nov 8, 2017 · 8-6 Dense cataract and patchy iris atrophy in an eye after an attack of acute angle-closure glaucoma. ... dilation is due to angle closure.
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Essential iris atrophy is one of three iridocorneal endothelial (ICE) syndromes, each of which usually affects one eye of young to middle-aged men and women.
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Iris Atrophy - an overview | ScienceDirect Topics
An atrophied iris sphincter does not respond and the pupil remains dilated. ... Glaucoma develops in most eyes with progressive iris atrophy and Cogan-Reese ...
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Mydriasis - Humanitas.net
Mydriasis is a condition in which the pupil diameter exceeds 5 mm.Typically associated with poor lighting, it can also be caused by drugs, drugs or large ...
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Anisocoria - EyeWiki
Jun 18, 2025 · Pharmacologic anisocoria can present as mydriasis or miosis ... Scopolamine patch-induced unilateral mydriasis. Pediatrics. 1995;96 ...
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Acute Angle-Closure Glaucoma - StatPearls - NCBI Bookshelf - NIH
Nov 26, 2023 · Acute angle-closure glaucoma presents as a sudden onset of severe unilateral eye pain ... halos around bright lights, nausea, and vomiting.
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Traumatic brain injury: Mechanisms, manifestations, and visual ...
The pupil may no longer be round if damage is asymmetric. Muscle damage can lead to traumatic pupillary dilation (traumatic mydriasis on the ipsilateral side) ( ...Missing: neuropathy | Show results with:neuropathy
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Are Bilaterally Fixed and Dilated Pupils the Kiss of Death in Patients ...
Along with altered mental status and coma, a fixed and dilated pupil is often the sign of transtentorial brain herniation caused by a space-occupying ...
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Autoimmune Autonomic Ganglionopathy: Causes & Treatment
What are the symptoms of autoimmune autonomic ganglionopathy? · Constipation. · Dilated pupils (Adie's pupils). · Dry mouth or dry eyes. · Fainting (syncope). · Low ...
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Aug 19, 2024 · Symptoms. Signs and symptoms of increased pressure inside the skull (that may lead to brain herniation) may include: High blood pressure. ...
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Fundoscopic Exam (Ophthalmoscopy) | Stanford Medicine 25
Fundoscopic examination is a visualization of the retina using an ophthalmoscope to diagnose high blood pressure, diabetes, endocarditis, ...Ophthalmoscope Settings · Technique --> Finding The... · Dilating The Pupil For The...
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Pupillary Responses | Stanford Medicine 25
The physiology behind a "normal" pupillary constriction is a balance between the sympathetic and parasympathetic nervous systems.Missing: anatomy | Show results with:anatomy
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Jun 2, 2025 · The Slit Lamp biomicroscope is the fundamental diagnostic tool for ocular examination. This overview will describe features and functions of ...
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including inside them. It's a common part of a routine eye exam ...Missing: integrity | Show results with:integrity
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Horner Syndrome - EyeWiki
Jul 9, 2025 · Horner syndrome is diagnosed clinically by observing ptosis of the upper and lower lids, miosis of the ptotic eye and demonstration of dilation ...
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Horner Syndrome - StatPearls - NCBI Bookshelf
Horner syndrome is a rare condition classically presenting with partial ptosis (drooping or falling of the upper eyelid), miosis (constricted pupil), and facial ...
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Fixed dilated pupil DDx • LITFL • CCC Differential Diagnosis
Feb 23, 2023 · A single fixed dilated (mydriatic) pupil can be caused by: Pharmacological blockade– typically topical mydriatic drugs used to facilitate ophthalomological ...
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The differential diagnosis of fixed dilated pupils: a case report and ...
This case report describes a patient with Guillain-Barré syndrome in whom the presence of coma and absent brain stem reflexes suggested the possibility of ...
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Benign Episodic Mydriasis as a Cause of Isolated Anisocoria - PMC
Benign episodic mydriasis is a diagnosis of exclusion that may be considered only after the life- and eyesight-threatening causes of anisocoria.
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Tropicamide - StatPearls - NCBI Bookshelf - NIH
Mechanism for Dilation. As a parasympathetic antagonist, tropicamide exerts its dilatory effects by acting on the pupillary sphincter muscle to cause its ...
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Ryzumvi: pioneering advances in countering drug-induced mydriasis
Apr 17, 2024 · The blockade of parasympathetic muscarinic acetylcholine receptors on the iris sphincter muscle causes anticholinergic mydriasis, while ...
[75]
Surgical reconstruction of the iris-lens-diaphragm with an iris implant ...
Iridodialysis is usually treated using sutures and can be combined with pupilloplasty to treat traumatic mydriasis. A variety of suturing techniques have been ...
[76]
A Pharmacologic Pupillary Test in the Diagnosis of Diabetic ... - NIH
The most common pupillary sign in diabetes is miosis. · It has been suggested that failure of sympathetically-mediated pupil dilation is the mechanism of reduced ...<|separator|>
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Increased Intracranial Pressure - StatPearls - NCBI Bookshelf - NIH
Sep 14, 2025 · Intracranial hypertension refers to a clinical condition characterized by elevated pressure within the cranial vault.
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Mydriatic - FPnotebook
Dec 2, 2019 · Tropicamide 0.5% - 1% (Mydriacyl). Onset: 20-40 minutes; Duration: 4-8 hours in most cases (may last as long as 24 hours) ; Phenylephrine ...
[79]
Mydriasis - an overview | ScienceDirect Topics
Differential Diagnosis. I. Efferent mydriasis. II. Pharmacological blockade via iris sphincter paralysis (e.g., atropine). III. Intraocular diseases. A ...
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Will damage to the iris sphincter heal over time?
Oct 25, 2019 · Will damage from blunt trauma to the iris sphincter (resulting in mydriasis, or dilated eye) heal over time? Answer: It may. Only time will ...
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Traumatic Iridodialysis Associated With Hyphema Secondary to ...
Feb 11, 2021 · The sphincter muscles become irreversibly damaged and the subsequent mydriasis causes visual disturbances including glaucoma [4]. Hyphema is ...
[82]
Brain stem blood flow, pupillary response, and outcome in ... - PubMed
A decrease in brain stem blood flow (BBF) is a more frequent cause of mydriasis and brain stem symptomatology after severe head injury.
[83]
Regression analysis between age and mydriatric effect of 2.5 ...
The difference in pupil size after 2.5% phenylephrine was correlated with age (r = 0.37 and 0.36, p-value < 0.01). The difference in pupil size after 10% ...
[84]
Eclectic Ocular Comorbidities and Systemic Diseases with Eye ...
Specific diseases are openly acknowledged to affect the eyes and vision, such as diabetes mellitus, hypertension blood pressure, arthritis, hyperthyroidism, ...Missing: mydriasis prognosis
[85]
Association between pupillary examinations and prognosis in ...
Mar 6, 2024 · Specifically, a negative pupillary light reflex (PLR) and mydriasis upon hospital arrival are associated with poor prognostic outcomes [9, 10].