Information about the loss of visual field
In the case of a hemianopsia (hemianopsia) there is a limitation of spatial vision. The field of view is the area that is detected when the eyes are still looking forward.
What is a loss of visual field?
Normal vision is restricted in the event of a visual field failure. The normal field of view is characterised by sharp vision in the middle range and rather blurred contours at the left and right edges. In the peripheral areas, however, movements can still be perceived. Field of view defects can be one-sided (monocular hemianopsia) or affect both eyes (binocular hemianopsia). In addition, there are visual field failures that restrict vision at close range ("central" hemianopsies) and those that affect distant vision (peripheral hemianopsies). The healthy long-range field of view enables sleep-side vision up to 90 degrees to the left and right, up to 70 degrees down and up, and up to 60 degrees towards the nose. In the course of life, the visual field deteriorates during normal aging. The visual field can also be individually different due to habituation factors.In addition, the color, brightness and size of the objects viewed influence the field of view. If an insular area within the visual field is no longer recognized, a so-called "scotoma" is present. In the event of a "concentric" partial loss of the visual field, the outer visual areas are restricted. Metamorphopsies are caused by image distortion. In a hemianopsia , the field of view is not visible on the left or right side. There is also the possibility of a quadrant anopsy, in which one quarter of the visual range is affected by a visual field loss (quadrant failure).
A visual field loss can occur as a result of eye or brain diseases. Possible illnesses leading to hemianopsia include pathological changes in the visual pathway, optic optic nerve crossing (Chiasma opticum),the optic nerve pathways and the visual centres in the visual cortex and brain. Retinopathy is a retinal damage. Macular degeneration, which usually occurs after the age of 60, only impairs central vision. Cataract (gray cataract),which can lead to blindness if untreated, is caused by clouding of the eye lens. Glaucoma (green cataract) is caused by an increase in intraocular pressure, which can damage the optic nerve. Eye and head injuries of all kinds as well as migraine attacks can also lead to a visual field loss. A hemianopsia can be triggered by cerebral haemorrhage, stroke (apoplexy) or the enlargement of an arterial blood vessel (aneurysm) in the brain. In addition, brain tumors can cause a visual field failure.
When should one see a doctor?
In the event of a visual field failure, there is a disorder somewhere in the optic nerve between the retina and the visual centre in the brain. This can also be located on the retina itself. It is true that a temporary loss of visual field can also occur due to overexertion of the eyes. Nevertheless, it is strongly recommended to consult a doctor immediately in the event of a field of vision failure: an ophthalmologist or a neurologist. It can be damage to the eyeball itself that causes a visual field loss, such as damage to the retina, age-related macular degeneration, eye injuries, bleeding on or in the eyes as well as cataract or glaucoma. One of the aims of the treatment is to prevent the risk of blindness and to maintain vision in the best possible way. In addition to such eye diseases, a visual field failure can also be caused by a migraine attack or stroke as well as a brain tumour or brain aneurysm. A visual field failure can also be the result of an accident with severe head injury. In the case of a visual field failure, the underlying disease determines the therapy. If it is not possible or only possible to restore previous vision, the physician will endeavour to work with his patient to find solutions for the best possible compensation of the impairment.
Preventive measures are not possible in the case of a purely age-related loss of field of vision and even in the case of cataract. The risk of visual field loss in the form of a glaucoma can be limited by regularly measuring intraocular pressure, especially after cortisone medication and after injuries. Aneurysms can be avoided in some cases by abstaining from smoking and by avoiding excessive alcohol consumption that increases blood pressure. Too high cholesterol and overweight also increase the risk of aneurysm or stroke, while physical exercise reduces the risk of losing sight of the field of vision.
Treatment optionsIn the case of sudden events (such as a stroke or cerebral haemorrhage caused by external violence) that lead to a loss of visual field, early treatment may lead to a regression of the visual field. In a stroke, an attempt is made to dissolve a blood clot (thrombolysis) that may be present in the brain by administering medication.
Often, however, visual field failures cannot be reversed, so that a restorative therapy is not possible..
However, an improvement in everyday life can be achieved by compensatory visual training, So through targeted eye movements to the blind side, the eyes are trained:
«Significant behavioral improvements»[...] we would like to argue that compensatory approaches have come further towards the aim of establishing their clinical efficacy than either the VRT approaches or the use of optical aids. In the case of compensatory approaches several studies found significant behavioral improvements following the training.
Lane et al. (2008)
Link to the review
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