Mydriasis
Mydriasis—pupillary dilation caused by contraction of the dilator of the iris—is a normal response to decreased light, strong emotional stimuli, and topical administration of mydriatic and cycloplegic drugs. It can also result from ocular and neurologic disorders, eye trauma, and disorders that decrease the level of consciousness (LOC). Mydriasis may be an adverse effect of antihistamines or other drugs.
History and physical examination
Begin by asking the patient about eye problems, such as pain, blurring, diplopia, or visual field defects. Obtain a health history, focusing on eye or head trauma, glaucoma and other ocular problems, and neurologic and vascular disorders. In addition, obtain a complete drug history.
Next, perform a thorough eye examination. Inspect and compare the pupils' size, color, and shape—many people normally have unequal pupils. (See Grading pupil size.) Also, test each pupil for light reflex, consensual response, and accommodation. Perform a swinging flashlight test to evaluate a decreased response to direct light coupled with a normal consensual response (Marcus Gunn pupil). Be sure to check the eyes for ptosis, swelling, and ecchymosis. Test visual acuity in both eyes with and without correction. Evaluate extraocular muscle function by checking the six cardinal fields of gaze.
Keep in mind that mydriasis appears in two ocular emergencies: acute angle-closure glaucoma and traumatic iridoplegia.
Medical causes
Adie's syndrome.Adie's syndrome is characterized by abrupt unilateral mydriasis, poor or absent pupillary reflexes, visual blurring, and cramplike eye pain. Deep tendon reflexes (DTRs) may be hyperactive or absent, especially the ankle and knee jerk reflexes.
Aortic arch syndrome.Bilateral pupillary mydriasis commonly occurs late in aortic arch syndrome. Other ocular findings include visual blurring, transient vision loss, and diplopia. Related findings include dizziness and syncope; neck, shoulder, and chest pain; bruits; loss of radial and carotid pulses; paresthesia; and intermittent claudication. Blood pressure may be decreased in the arms.
Botulism.Botulism toxin causes bilateral mydriasis, usually 12 to 36 hours after ingestion. Other early findings are a loss of pupillary reflexes, visual blurring, diplopia, ptosis, strabismus and extraocular muscle palsies, anorexia, nausea, vomiting, diarrhea, and dry mouth. Vertigo, hearing loss, hoarseness, hypernasality, dysarthria, dysphagia, progressive muscle weakness, and a loss of DTRs soon follow.
Carotid artery aneurysm.With carotid artery aneurysm, unilateral mydriasis may be accompanied by bitemporal hemianopsia, decreased visual acuity, hemiplegia, decreased LOC, headache, aphasia, behavioral changes, and hypoesthesia.
Glaucoma (acute angle-closure).Acute angle-closure glaucoma is an ocular emergency that's characterized by moderate mydriasis and the loss of pupillary reflex in the affected eye, accompanied by an abrupt onset of excruciating pain, redness, decreased visual acuity, visual blurring, halo vision, conjunctival injection, and a cloudy cornea. Without treatment, permanent blindness occurs in 2 to 5 days.
Oculomotor nerve palsy.Unilateral mydriasis is commonly the first sign of oculomotor nerve palsy. It's soon followed by ptosis, diplopia, decreased pupillary reflexes, exotropia, and complete loss of accommodation. Focal neurologic signs may accompany signs of increased intracranial pressure.
Traumatic iridoplegia.Eye trauma can paralyze the sphincter of the iris, causing mydriasis and the loss of pupillary reflex; usually, this is transient. Associated findings include a quivering iris (iridodonesis), ecchymosis, pain, and swelling.
Other causes
Drugs.Mydriasis can be caused by anticholinergics, antihistamines, sympathomimetics, barbiturates (in overdose), estrogens, and tricyclic antidepressants; it also commonly occurs early in general anesthesia induction. Topical mydriatics and cycloplegics, such as phenylephrine, atropine, homatropine, scopolamine, cyclopentolate, and tropicamide, are administered specifically for their mydriatic effects.
Surgery.Traumatic mydriasis commonly results from ocular surgery.
Nursing considerations
▪ Prepare the patient for diagnostics tests, such as a complete ophthalmologic examination and a thorough neurologic workup.
Patient teaching
▪ Explain diagnostic tests to the patient.
▪ If the patient's mydriasis is the result of mydriatic drugs received during an eye examination, explain that he'll temporarily experience some photophobia and loss of accommodation.
Pictures
Book Source Details
- Book Title: Nursing: Interpreting Signs and Symptoms
- Author(s): Springhouse
- Year of Publication: 2007
- Copyright Details: Nursing: Interpreting Signs and Symptoms, Copyright © 2007 Lippincott Williams & Wilkins.
Other Book Chapters Related to Pupil symptoms
Read excerpts from these other book chapters related to Pupil symptoms:
Medical Books Excerpts
- Mydriasis
- "Handbook of Signs & Symptoms (Third Edition)" (2006)
- [ read ]
- Mydriasis
- "Professional Guide to Signs & Symptoms (Fifth Edition)" (2006)
- [ read ]
- Mydriasis
- "Signs & Symptoms: A 2-in-1 Reference for Nurses" (2007)
- [ read ]
- Mydriasis
- "Nursing: Interpreting Signs and Symptoms" (2007)
- [ read ]
Copyright Details: Nursing: Interpreting Signs and Symptoms, Copyright © 2008 Williams & Wilkins.
More About Causes of Pupil symptoms
» Next page: Pupils, nonreactive (Nursing: Interpreting Signs and Symptoms)
Rate This Website
What do you think about the features of this website?
Take our user survey and have your say:
Website User Survey
Medical Tools & Articles:
Next articles:
Tools & Services:
Medical Articles:
Forums & Message Boards
- Ask or answer a question at the Boards:
