Examples of using Visual field in English and their translations into Malayalam
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Visual field loss.
Measuring the visual field.
Visual field(confrontation) testing.
Views of Paris showing vision with loss of both temporal visual fields.
Visual field of a patient with glaucoma.
Blindness, Recovery from blindness Amblyopia, Nystagmus, Strabism, Stereoblindness, Stereopsis recovery Visual field.
The visual fields for neural lesions or nystagmus are tested via an evaluation of particular eye movements.
Dubious The blind spotis at about 15.5° in the outside direction(e.g. in the left visual field for the left eye).[24].
Common problems of the visual field include scotoma(area of reduced vision), hemianopia(half of visual field lost), homonymous hemianopsia and bitemporal hemianopia.
Homonymous hemianopia is atype of blindness that destroys one entire side of the visual field typically caused by injury in the primary visual cortex.
Ocular hypertension(OHT) is defined by intraocular pressure being higher than normal,in the absence of optic nerve damage or visual field loss.[9][10].
Light spot patterns testing the central 24 degrees or30 degrees of the visual field, are most commonly used. Most perimeters are also capable of testing up to 80 or 90 degrees.
Information from the right visual field(now on the left side of the brain) travels in the left optic tract. Information from the left visual field travels in the right optic tract. Each optic tract terminates in the lateral geniculate nucleus(LGN) in the thalamus.
A full eye examination consists of an external examination, followed by specific tests for visual acuity, pupil function,extraocular muscle motility, visual fields, intraocular pressure and ophthalmoscopy through a dilated pupil.
Quadrantanopia is a type of blindness that destroys only a part of the visual field typically caused by partial injury in the primary visual cortex. This is very similar to homonymous hemianopia, but to a lesser degree.
Glare is typically measured with luminance meters or luminance cameras, both of which are able to determine the luminance of objects within small solid angles.The glare of a scene i.e. visual field of view, is then calculated from the luminance data of that scene.
Glaucoma is a type of blindness that begins at the edge of the visual field and progresses inward. It may result in tunnel vision. This typically involves the outer layers of the optic nerve, sometimes as a result of buildup of fluid and excessive pressure in the eye.[53].
The visual pathway consists of structures that carry visual information from the retina to the brain.Lesions in the that pathway cause a variety of visual field defects. The type of field defect can help localize where the lesion is located(see figure).
The normal(monocular) human visual field extends to approximately 60 degrees nasally(toward the nose, or inward) from the vertical meridian in each eye, to 107 degrees temporally(away from the nose, or outwards) from the vertical meridian, and approximately 70 degrees above and 80 below the horizontal meridian.[ 3][ 4][ 5][ 6].
Generalized depression: Generalized depression is seen in early stages of glaucoma and many other conditions.Mild constriction of the central and peripheral visual field due to isopter contraction comes under generalized depression. If all the isopters show similar depression to the same point, it is called a contraction of the visual field.
In glaucoma, visual field defects result from damage to the retinal nerve fiber layer.Field defects are seen mainly in primary open angle glaucoma. Because of the unique anatomy of the RNFL, many noticeable patterns are seen in the visual field. .
Cerebral palsy: Field loss due to cerebral palsy may be hemianopic affecting even upper or lower half, central scotoma, peripheral scotoma, or islands of vision.[16] Epilepsy: Although field defects are rarely associated with epilepsy[17], defects may occur after temporal lobe surgery for epilepsy.[18] Periventricular leukomalacia(PVL):Bilateral inferior visual field defects may occur due to damage of the optic radiations[19].
The macula of the retina is the central area in the visual field of about 10 to 17 deg diameter(in visual angle). It is responsible for high-resolution vision in good light, in particular for reading. Many diseases affecting the macula may cause defects in the central field of vision, among them Metamorphopsia and central scotomas.
From the lateral geniculate body, fibers of the optic radiation pass to the visual cortex in the occipital lobe of the brain. In more specific terms,fibers carrying information from the contralateral superior visual field traverse Meyer's loop to terminate in the lingual gyrus below the calcarine fissure in the occipital lobe, and fibers carrying information from the contralateral inferior visual field terminate more superiorly, to the cuneus.[7].
The classical image on the shape and size of the visual field by Harry Moss Traquair in his book“Clinical Perimetry”(1938;modified to show the essentials). It shows that the visual field is considerably larger on the temporal side than the often quoted 90° extent. Similar limits were already reported in the 19th century.
In the second stage, abnormal new blood vessels(neovascularisation) form at the back of the eye as part of proliferative diabetic retinopathy(PDR); these can burst and bleed(vitreous hemorrhage) and blur the vision, because these new blood vessels are fragile. The first time this bleeding occurs, it may not be very severe. In most cases, it will leave just a few specks of blood,or spots floating in a person's visual field, though the spots often go away after a few hours.
Dynamic, continuous, tiny dots in the entire visual field. Additional visual symptoms of at least two of the following four types: Palinopsia(visual trailing and afterimages) Enhanced entoptic phenomena(floaters, photopsia, blue field entoptic phenomenon, phosphenes) Photophobia Impaired night vision Symptoms are not consistent with typical migraine aura. Symptoms are not attributed to another disorder(ophthalmological, drug abuse).
The Amsler grid, used since 1945, is a grid of horizontal andvertical lines used to monitor a person's central visual field. The grid was developed by Marc Amsler, a Swiss ophthalmologist. It is a diagnostic tool that aids in the detection of visual disturbances caused by changes in the retina, particularly the macula(e.g. macular degeneration, Epiretinal membrane), as well as the optic nerve and the visual pathway to the brain.
Field defects in visual pathway lesions.
I have a congenital visual impairment that restricts my field of vision.