同: 両鼻側半盲

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/02/24 08:59:45」(JST)

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Paris as seen with full visual fields

Binasal hemianopsia (or Binasal hemianopia) is the medical description of a type of partial blindness where vision is missing in the inner half of both the right and left visual field. It is associated with certain lesions of the eye and of the central nervous system, such as congenital hydrocephalus.

Etymology

The absence of vision in half of a visual field is described as hemianopsia.

The visual field of each eye can be divided in two vertically, with the outer half being described as temporal, and the inner half being described as nasal.

"Binasal hemianopsia" can be broken down as follows:

bi-: involves both left and right visual fields
nasal: involves the nasal visual field
temporal: involves the temporal visual field
lateral: involves the lateral visual field
hemi-: involves half of each visual field
anopsia: blindness

Causes

In binasal hemianopsia, vision is missing in the inner (nasal or medial) half of both the right and left visual fields. Information from the nasal visual field falls on the temporal (lateral) retina. Those lateral retinal nerve fibers do not cross in the optic chiasm. Calcification of the internal carotid arteries can impinge the uncrossed, lateral retinal fibers leading to loss of vision in the nasal field.

Note: Clinical testing of visual fields (by confrontation) can produce false positive result (particularly in inferior nasal quadrants).

External links

919601218 at GPnotebook

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English Journal

Impaired reading not due to visual field loss in a patient with a right-hemipsheric lesion.

Basagni B1, Patané I, Ferrari V, Bruno N.
Neurocase.Neurocase.2014 Oct;20(5):510-23. doi: 10.1080/13554794.2013.826684. Epub 2013 Aug 28.
We describe a right-handed patient (M.B.), who developed left hemianopsia and a severe reading impairment after right occipital-parietal hemorrhage. The pattern of his reading deficit was very similar to that of pure alexia (alexia-without-agraphia): extremely slow reading times with frequent graphe
PMID 23984952

Hemifield slide from traumatic optic chiasmopathy.

Pula JH1, Fischer M2, Kattah JC2.
Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia.J Clin Neurosci.2014 Aug;21(8):1446-7. doi: 10.1016/j.jocn.2014.01.001. Epub 2014 Jan 24.
A 56-year-old man suffered a high velocity linear acceleration closed head injury, resulting in skull fractures including bone dehiscence at the planum sphenoidale and tuberculum sellae. After regaining consciousness, he reported blurry vision and episodic diplopia. Visual field testing showed a bit
PMID 24613428

Visual-evoked potentials in patients with brain circulatory problems.

Pojda-Wilczek D.
The International journal of neuroscience.Int J Neurosci.2014 Jul 2. [Epub ahead of print]
Purpose: The aim of this study was to find out if local brain circulatory problems may influence visual-evoked potentials (VEP). Patients and methods: Thirty-eight patients were divided into the following groups: (I) those with hemianopsia or quadrantanopsia and hemiparesis after brain stroke; (II)
PMID 24901952