STUDY - Technical - New Dacian's Medicine
Ocular
deviation (Classical / Allopathic Medicine)
Ocular deviation
refers to abnormal eye movement that may be conjugate (both
eyes move together) or dysconjugate (one eye moves differently
from the other). This common sign may result from an ocular,
neurologic, endocrine, or systemic disorder that interferes
with the muscles, nerves, or brain centers governing eye
movement. Occasionally, it signals a life-threatening disorder
such as a ruptured cerebral aneurysm. (See Ocular deviation:
Characteristics and causes in cranial nerve damage.)
Normally, eye
movement is directly controlled by the extraocular muscles
innervated by the oculomotor, trochlear, and abducens nerves
(cranial nerves III, IV, and VI). Together, these muscles and
nerves direct a visual stimulus to fall on corresponding parts
of the retina. Dysconjugate ocular deviation may result from
unequal muscle tone (nonparalytic strabismus) or from muscle
paralysis associated with cranial nerve damage (paralytic
strabismus). Conjugate ocular deviation may result from
disorders that affect the centers in the cerebral cortex and
brain stem responsible for conjugate eye movement. Typically,
such disorders cause gaze palsy - difficulty moving the eyes
in one or more directions.
ALERT:
If the patient displays ocular deviation:
- quickly take his vital signs
- look for an altered level of consciousness, pupil changes, motor or sensory dysfunction, and severe headache
- if possible, ask his family about behavioral changes or a history of recent head trauma
- institute emergency measures, if needed.
If the patient's condition permits, perform a focused assessment.
If the patient displays ocular deviation:
- quickly take his vital signs
- look for an altered level of consciousness, pupil changes, motor or sensory dysfunction, and severe headache
- if possible, ask his family about behavioral changes or a history of recent head trauma
- institute emergency measures, if needed.
If the patient's condition permits, perform a focused assessment.
Ocular deviation:
Characteristics and causes of cranial nerve damage
Characteristics: Inability
to focus the eye upward, downward, inward, and outward;
drooping eyelid; and, except in diabetes, a dilated pupil in
the affected eye
Cranial nerve and
extraocular muscles involved: Oculomotor
nerve (III); medial rectus, superior rectus, inferior rectus,
and inferior oblique muscles
Probable causes: Cerebral
aneurysm, diabetes, temporal lobe herniation from increased
intracranial pressure, brain tumor
Characteristics: Loss of downward and outward movement in the affected eye
Cranial nerve
and extraocular muscles involved: Trochlear
nerve (IV); superior oblique muscle
Probable causes:
Head trauma
Characteristics: Loss
of outward movement in the affected eye
Cranial nerve
and extraocular muscles involved: Abducens
nerve (VI); lateral rectus muscle
Probable causes:
Brain tumor
HISTORY:
Ask the patient how long he has had the ocular deviation and if it's accompanied by double vision, eye pain, or headache.
Ask the patient whether he has noticed associated motor or sensory changes or fever.
Review the patient's medical history for hypertension; diabetes; allergies; thyroid, neurologic, or muscular disorders; extraocular muscle imbalance; eye or head trauma; and eye surgery.
Ask the patient how long he has had the ocular deviation and if it's accompanied by double vision, eye pain, or headache.
Ask the patient whether he has noticed associated motor or sensory changes or fever.
Review the patient's medical history for hypertension; diabetes; allergies; thyroid, neurologic, or muscular disorders; extraocular muscle imbalance; eye or head trauma; and eye surgery.
PHYSICAL
ASSESSMENT:
Observe the patient for partial or complete ptosis. Note if he spontaneously tilts his head or turns his face to compensate for ocular deviation.
Check for eye redness or periorbital edema. Assess visual acuity; then evaluate extraocular muscle function by testing the six cardinal fields of gaze.
Observe the patient for partial or complete ptosis. Note if he spontaneously tilts his head or turns his face to compensate for ocular deviation.
Check for eye redness or periorbital edema. Assess visual acuity; then evaluate extraocular muscle function by testing the six cardinal fields of gaze.
SPECIAL
CONSIDERATIONS:
If you suspect an acute neurologic disorder, take seizure precautions and monitor vital signs and neurologic status closely.
If you suspect an acute neurologic disorder, take seizure precautions and monitor vital signs and neurologic status closely.
PEDIATRIC
POINTERS:
In children, the most common cause of the ocular deviation is nonparalytic strabismus.
Although severe strabismus is readily apparent, mild strabismus must be confirmed by tests for misalignments, such as the corneal light reflex test and the cover test. Testing is crucial - early corrective measures help preserve binocular vision and cosmetic appearance. Also, mild strabismus may indicate retinoblastoma, a tumor that may be asymptomatic before age 2, except for a characteristic whitish reflex in the pupil.
In children, the most common cause of the ocular deviation is nonparalytic strabismus.
Although severe strabismus is readily apparent, mild strabismus must be confirmed by tests for misalignments, such as the corneal light reflex test and the cover test. Testing is crucial - early corrective measures help preserve binocular vision and cosmetic appearance. Also, mild strabismus may indicate retinoblastoma, a tumor that may be asymptomatic before age 2, except for a characteristic whitish reflex in the pupil.
PATIENT
COUNSELING:
Instruct the patient on what to expect from diagnostic testing, which may include blood studies, orbital and skull X-rays, and computed tomography scans.
Instruct the patient on what to expect from diagnostic testing, which may include blood studies, orbital and skull X-rays, and computed tomography scans.
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.