STUDY - Technical - New Dacian's Medicine
Pupils,
nonreactive (Classical / Allopathic Medicine)
Nonreactive
(fixed) pupils fail to constrict in response to light or
fail to dilate when the light is removed. The development
of a unilateral or bilateral nonreactive response
indicates an important change in the patient's condition
and may signal a life-threatening emergency and, possibly,
brain death. It also occurs with the use of certain optic
drugs.
To
evaluate pupillary reaction to light, first test the
patient's direct light reflex. Darken the room, and cover
one of the patient's eyes while you hold open the opposite
eyelid. Using a bright penlight, bring the light toward
the patient from the side and shine it directly into his
opened eye. If normal, the pupil will promptly constrict.
Next, test the consensual light reflex. Hold the patient's
eyelids open and shine the light into one eye while
watching the pupil of the opposite eye. If normal, both
pupils will promptly constrict. Repeat both procedures in
the opposite eye. A unilateral or bilateral nonreactive
response indicates dysfunction of cranial nerves II and
III, which mediate the pupillary light reflex. (See
Innervation of direct and consensual light reflexes.)
Innervation
of direct and consensual light reflexes
Two reactions - direct and consensual - constitute the pupillary light reflex. Normally, when a light is shined directly onto the retina of one eye, the parasympathetic nerves are stimulated to cause brisk constriction of that pupil - the direct light reflex. The pupil of the opposite eye also constricts - the consensual light reflex.
Two reactions - direct and consensual - constitute the pupillary light reflex. Normally, when a light is shined directly onto the retina of one eye, the parasympathetic nerves are stimulated to cause brisk constriction of that pupil - the direct light reflex. The pupil of the opposite eye also constricts - the consensual light reflex.
The
optic nerve (CN II) mediates the afferent arc of this
reflex from each eye, whereas the oculomotor nerve (CN
III) mediates the efferent arc to both eyes. A nonreactive
or sluggish response in one or both pupils indicates
dysfunction of these cranial nerves, usually due to
degenerative disease of the central nervous system.
ALERT:
If the patient is unconscious and develops unilateral or bilateral nonreactive pupils:
- quickly assess all vital signs
- be alert for decerebrate or decorticate posture, bradycardia, elevated systolic blood pressure, and other untoward changes in the patient's condition.
If the patient is conscious, perform a focused assessment.
ALERT:
If the patient is unconscious and develops unilateral or bilateral nonreactive pupils:
- quickly assess all vital signs
- be alert for decerebrate or decorticate posture, bradycardia, elevated systolic blood pressure, and other untoward changes in the patient's condition.
If the patient is conscious, perform a focused assessment.
HISTORY:
Ask the patient what type of eyedrops he's using, if any, and when they were last instilled.
Ask the patient if he's experiencing pain and, if so, ask him to describe its location, intensity, and duration.
Obtain a drug history, including prescription and over-the-counter drugs, herbal remedies, and recreational drugs.
Ask the patient what type of eyedrops he's using, if any, and when they were last instilled.
Ask the patient if he's experiencing pain and, if so, ask him to describe its location, intensity, and duration.
Obtain a drug history, including prescription and over-the-counter drugs, herbal remedies, and recreational drugs.
PHYSICAL
ASSESSMENT:
Take the patient's vital signs.
Assess extraocular movement to evaluate cranial nerves III, IV, and VI.
Assess the patient for photosensitivity and photophobia. Check both eyes for visual acuity.
Test the pupillary reaction to accommodation. Then, hold a penlight at the side of each eye, and examine the cornea and iris for abnormalities.
Estimate intraocular pressure (IOP) by placing your second and third fingers over the patient's closed eyelid. If the eyeball feels rock hard, suspect elevated IOP.
After the examination, be sure to cover the affected eye with a protective metal shield but don't let the shield rest on the globe.
Take the patient's vital signs.
Assess extraocular movement to evaluate cranial nerves III, IV, and VI.
Assess the patient for photosensitivity and photophobia. Check both eyes for visual acuity.
Test the pupillary reaction to accommodation. Then, hold a penlight at the side of each eye, and examine the cornea and iris for abnormalities.
Estimate intraocular pressure (IOP) by placing your second and third fingers over the patient's closed eyelid. If the eyeball feels rock hard, suspect elevated IOP.
After the examination, be sure to cover the affected eye with a protective metal shield but don't let the shield rest on the globe.
SPECIAL
CONSIDERATIONS:
Instillation of a topical mydriatic or a cycloplegic may induce a temporarily nonreactive pupil in the affected eye.
Instillation of a topical mydriatic or a cycloplegic may induce a temporarily nonreactive pupil in the affected eye.
PEDIATRIC
POINTERS:
Children have nonreactive pupils for the same reasons as adults. The most common cause is oculomotor nerve palsy from increased intracranial pressure.
Children have nonreactive pupils for the same reasons as adults. The most common cause is oculomotor nerve palsy from increased intracranial pressure.
PATIENT
COUNSELING:
If the patient is unconscious, tell his family that the patient's eyes will be kept closed (possibly using tape) to prevent corneal exposure.
If the patient is unconscious, tell his family that the patient's eyes will be kept closed (possibly using tape) to prevent corneal exposure.
Bibliography:
1. Rapid Assessment, A
Flowchart Guide to Evaluating Signs & Symptoms, Lippincott
Williams & Wilkins, 2004.
2. Professional Guide to
Signs and symptoms, Edition V, Lippincott
Williams & Wilkins, 2007.
3. Guide to common symptoms,
Edition V, McGraw - Hill, 2002.