Bitemporal hemianopia: Difference between revisions
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* ''hemi-'': involves half of each visual field | * ''hemi-'': involves half of each visual field | ||
* ''anopsia'': blindness (formed by ''a(n) <sup>no</sup> + opsis <sup>vision</sup> + ia'') | * ''anopsia'': blindness (formed by ''a(n) <sup>no</sup> + opsis <sup>vision</sup> + ia'') | ||
==Pathophysiology== | |||
Hemianopia results from a lesion of the [[optic chiasm]]. This is the area where optic nerves from the right side of the brain cross over to the left and vice versa. Visual information from the temporal [[visual field]] is transmitted by the nasal retina and information from the nasal field is transmitted by the temporal [[retina]]. At the [[optic chiasm]], nasal fibers of the [[retina]] cross over to other side of the brain and carry information to the higher visual brain centers. Thus, a lesion in the [[optic chiasm]] affects the nasal fibers of both [[retina]]s. It is when this disruption in the circuitry occurs that there is a loss of information from both of the outer visual fields. | |||
== [[Bitemporal hemianopia overview|Overview]] == | == [[Bitemporal hemianopia overview|Overview]] == | ||
Revision as of 18:15, 30 November 2012
Template:DiseaseDisorder infobox
Template:Bitemporal hemianopia
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-In-Chief:Aditya Govindavarjhulla, M.B.B.S. [2]
Synonyms and keywords: Bitemporal hemianopsia
Overview
Bitemporal hemianopia is a specific type of visual disturbance in which sight in the outer half of the visual field of each eye is lost. As a result, the patient retains central vision but loses sight at the edges of his or her vision. This is not always obvious to a patient because one tends to focus conscious attention more on objects in the center of the visual field.
Hemianopia signifies a loss of half of the visual field, and bitemporal denotes the two lateral, or temporal, sides of the head. By contrast, homonymous hemianopia signifies that the same half of each visual field is lost, ie all vision on the left, or on the right, of the midline. Such a pattern of visual loss is caused by damage to the more distal part of the optic radiation, most commonly by a stroke.
Etymology
"Bitemporal hemianopia" can be broken down as follows:
- bi-: involves both left and right visual fields
- temporal: involves the temporal visual field
- hemi-: involves half of each visual field
- anopsia: blindness (formed by a(n) no + opsis vision + ia)
Pathophysiology
Hemianopia results from a lesion of the optic chiasm. This is the area where optic nerves from the right side of the brain cross over to the left and vice versa. Visual information from the temporal visual field is transmitted by the nasal retina and information from the nasal field is transmitted by the temporal retina. At the optic chiasm, nasal fibers of the retina cross over to other side of the brain and carry information to the higher visual brain centers. Thus, a lesion in the optic chiasm affects the nasal fibers of both retinas. It is when this disruption in the circuitry occurs that there is a loss of information from both of the outer visual fields.
Overview
Historical Perspective
Pathophysiology
Causes
Natural history and Complications
Diagnosis
History and Symptoms |Physical Examination |Laboratory tests |Electrocardiogram | Chest X Ray | CT | MRI | Echocardiography or Ultrasound | Other imaging studies | Alternative diagnostics
Treatment
Medical therapy | Surgical therapy