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 level of consciousness (LOC). Mydriasis may be an adverse effect of antihistamines or other drugs.
History
Begin by asking the patient about any other 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.
Physical assessment
Perform a thorough eye and pupil 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.
CULTURAL CUE:When examining the eyes, keep in mind that not all cultures consider maintaining eye contact socially acceptable. For example, some Asian and Native American groups view eye contact as an invasion of privacy. The Navajo consider eye contact rude. Certain Indian cultures regard eye contact as an indicator of social status.
Keep in mind that mydriasis appears in two ocular emergencies: acute angle-closure glaucoma and traumatic iridoplegia.
Medical causes
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.
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 characterized by moderate mydriasis and loss of pupillary reflex in the affected eye, accompanied by 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 (ICP).
Traumatic iridoplegia
Eye trauma can paralyze the sphincter of the iris, causing mydriasis and 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 (overdose), estrogens, and tricyclic antidepressants; it also commonly occurs early in 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.
Special considerations
Diagnostic tests may vary, depending on your findings, but may include a complete ophthalmologic examination and a thorough neurologic workup. Explain any diagnostic tests to the patient.
Pediatric pointers
Mydriasis occurs in children as a result of ocular trauma, drugs, Adie’s syndrome and, most commonly, increased ICP.
Patient counseling
If the patient’s mydriasis is the result of mydriatic drugs received during an eye examination, explain that he’ll likely experience some photophobia and loss of accommodation. Instruct him to wear dark glasses and to avoid bright light, and reassure him that the condition is only temporary.
Pictures
Book Source Details
- Book Title: Signs & Symptoms: A 2-in-1 Reference for Nurses
- Author(s): Springhouse
- Year of Publication: 2007
- Copyright Details: Signs & Symptoms: A 2-in-1 Reference for Nurses, 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: Signs & Symptoms: A 2-in-1 Reference for Nurses, Copyright © 2008 Williams & Wilkins.
More About Causes of Pupil symptoms
» Next page: Pupils, nonreactive (Signs & Symptoms: A 2-in-1 Reference for Nurses)
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