STUDY - Technical - New Dacian's Medicine
Hemianopsia
(Classical / Allopathic Medicine)
Hemianopsia is the
loss of vision in half the visual field of one or both eyes.
However, if the visual field defects are identical in both
eyes but affect less than half the field of vision in each eye
(incomplete homonymous hemianopsia), the lesion may be in the
occipital lobe; otherwise, it probably involves the parietal
or temporal lobe.
Hemianopsia is
caused by a lesion affecting the optic chiasm, tract, or
radiation. Defects in visual perception due to cerebral
lesions are usually associated with impaired color vision.
HISTORY:
Ask the patient when the vision problems began. Has he ever experienced hemianopsia before?
Ask the patient if he has recently experienced headaches, dysarthria, or seizures. Does he have ptosis or facial or extremity weakness? Is he experiencing hallucinations or loss of color vision?
Obtain a medical history, noting especially eye disorders, hypertension, and diabetes mellitus.
Ask the patient when the vision problems began. Has he ever experienced hemianopsia before?
Ask the patient if he has recently experienced headaches, dysarthria, or seizures. Does he have ptosis or facial or extremity weakness? Is he experiencing hallucinations or loss of color vision?
Obtain a medical history, noting especially eye disorders, hypertension, and diabetes mellitus.
PHYSICAL
ASSESSMENT:
Suspect a visual field defect if the patient seems startled when you approach him from one side or if he fails to see objects placed directly in front of him. To help determine the type of defect, perform the following:
Compare the patient's visual fields with your own - assuming that yours are normal. First, ask the patient to cover his right eye while you cover your left eye. Then move a pen or similarly shaped object from the periphery of his (and your) uncovered eye into his field of vision. Ask the patient to indicate when he first sees the object. Does he see it at the same time as you? After you? Repeat this test in each quadrant of both eyes.
For each eye, plot the defect by shading the area of a circle that corresponds to the area of vision loss.
Evaluate the patient's level of consciousness, take his vital signs, and check his pupillary reaction and motor response.
Suspect a visual field defect if the patient seems startled when you approach him from one side or if he fails to see objects placed directly in front of him. To help determine the type of defect, perform the following:
Compare the patient's visual fields with your own - assuming that yours are normal. First, ask the patient to cover his right eye while you cover your left eye. Then move a pen or similarly shaped object from the periphery of his (and your) uncovered eye into his field of vision. Ask the patient to indicate when he first sees the object. Does he see it at the same time as you? After you? Repeat this test in each quadrant of both eyes.
For each eye, plot the defect by shading the area of a circle that corresponds to the area of vision loss.
Evaluate the patient's level of consciousness, take his vital signs, and check his pupillary reaction and motor response.
SPECIAL
CONSIDERATIONS:
If the patient's visual field defect is significant, further visual field testing, such as perimetry or a tangent screen examination, may be indicated.
If the patient's visual field defect is significant, further visual field testing, such as perimetry or a tangent screen examination, may be indicated.
PEDIATRIC
POINTERS:
In children, a brain tumor is the most common cause of hemianopsia. To help detect this sign, look for nonverbal clues such as the child reaching for a toy but missing it.
In children, a brain tumor is the most common cause of hemianopsia. To help detect this sign, look for nonverbal clues such as the child reaching for a toy but missing it.
PATIENT
COUNSELING:
Explain to the patient the extent of his defect so that he can learn to compensate for it. Advise him to scan his surroundings frequently, turning his head in the direction of the defective visual field so that he can directly view objects he'd normally notice only peripherally.
Explain to the patient the extent of his defect so that he can learn to compensate for it. Advise him to scan his surroundings frequently, turning his head in the direction of the defective visual field so that he can directly view objects he'd normally notice only peripherally.
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.
Dorin,
Merticaru (2010)