Visual field loss (hemianopsia) is a reduction in spatial vision. The visual field is the area that is detected during vision when the nonmoving eyes are facing forward.
What is visual field loss?
Visual field defects can be unilateral or affect both eyes. There are also visual field defects that limit near vision and those that affect distance vision. In a visual field defect, normal vision is limited. For the normal visual field, sharp vision in the central area and rather blurred contours at the left and right edges are characteristic. However, movements can still be perceived in the peripheral areas. Visual field defects can be unilateral (monocular hemianopsia) or affect both eyes (binocular hemianopsia). There are also visual field defects that limit near vision (“central” hemianopsia) and those that affect distance vision (peripheral hemianopsia). The healthy distance visual field allows for sleep-sided vision up to more than 90 degrees to the left and right, up to 70 degrees down and up, and toward the nose up to 60 degrees. Over the course of life, the visual field deteriorates as part of the normal aging process. However, the visual field can also vary individually due to habituation factors. Furthermore, the color, brightness, and size of the objects viewed affect the visual field. If an island-shaped area within the visual field is no longer recognized, a so-called “scotoma” is present. In case of a “concentric” partial loss of the visual field, the outer visual areas are restricted. In metamorphopsia, image distortions are present. In hemianopsia, the visual field fails on the left or right side. Furthermore, there is the possibility of quadrant anopsia, in which a quarter of the visual field is affected by a visual field loss (quadrant loss).
Causes
Visual field loss can occur as a result of diseases of the eye or brain. Possible diseases leading to hermianopsia include pathologic changes in the visual pathway, optic chiasm, optic pathways, and visual centers located in the visual cortex and brain. In retinopathy, there is damage to the retina. The age-related macular degeneration, which usually only occurs after the age of 60, only leads to an impairment of the central vision. Cataract (cataract), which can lead to blindness if left untreated, is caused by clouding of the eye lens. Glaucoma (green cataract) is due to 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 cause visual field loss. Hermianopsia can be caused by cerebral hemorrhage, by a stroke (apoplexy), or by dilatation of an arterial blood vessel (aneurysm) in the brain. Furthermore, tumors in the brain can cause visual field loss.
Diseases with this symptom
- Cataract
- Stroke
- Aneurysm
- Blindness
- Cerebral hemorrhage
- Age-related macular degeneration
- Glaucoma (glaucoma)
- Migraine
- Thrombosis
Diagnosis and course
A visual field defect is diagnosed by a neurologist or an ophthalmologist. In the so-called perimetry (visual field examination), the patient looks with one eye or both eyes concentratedly at a luminous point and indicates at what point he perceives a presented object. The patient’s perceptual ability can thus be compared with the visual field of healthy people. One of the various methods of visual field diagnosis is the “controntation test” (“parallel test”), in which the doctor and patient sit opposite each other and each cover one eye while an object of observation is brought near. If the visual fields of the doctor and the patient differ from each other, a visual field defect can possibly be concluded. In the so-called kinetic perimetry, which is also a confontation test, a luminous point to be observed is brought near. In “automatic static perimetry”, which is often used, the light sensitivity of the retina is measured at specific points.Light points appearing in different sequences are confirmed by the patient after they have been recognized by pressing a signal key. Unrecognized light spots indicate a visual field defect. If a visual field defect is possibly due to certain diseases, the blood may be examined. X-ray examinations as well as computed tomography or magnetic resonance imaging and angiography (blood vessel examination after administration of contrast agents) may also be used in cases of visual field loss.
Complications
When defining complication, the culprit health disorder must be considered. A complication is a sequela of a condition or an undesirable side effect of a drug used to treat the condition in question. In this respect, complications can occur due to the overlooking of a condition as well as in the course of treatment. A visual field defect is a complication of glaucoma occurring in advanced cases, which belong to the disorders of the eye and thus of the sensory organs. Also, visual field loss could cause further complications such as, in the worst case, blindness in the affected eye. Visual field defects are caused by optic nerve damage due to constantly increased eye pressure. Complications occur more often in smokers or older patients. Visual field loss is not noticed at first when the healthy eye compensates for the loss. In order to avoid serious complications, an ophthalmologic examination should be performed when visual disturbances occur. Sometimes, in acute cases, to prevent further complications such as blindness, the affected person should be treated in the clinic and, if necessary, operated on. After that, the plan for outpatient treatment against the cause disease can be made. A diet that promotes blood flow, cutting out nicotine and preventing diabetes, as well as routine health screenings, visual field measurements and vision tests, can often prevent visual field loss. Various medications, for example, antidepressants, can trigger glaucoma and therefore should be chosen carefully.
When should you see a doctor?
In a visual field defect, there is a disturbance somewhere along the path of the optic nerve between the retina and the visual center in the brain. This may well already be on the retina itself. It is true that temporary visual field loss can also occur due to eye strain. Nevertheless, it is strongly recommended to see a doctor immediately in case of a visual field loss: an ophthalmologist or a neurologist. There may be damage to the eyeball itself that causes visual field loss, such as damage to the retina, age-related macular degeneration, eye injuries, bleeding on or in the eyes, and cataracts or glaucoma. In these cases, the treatment is aimed, among other things, at preventing the threat of blindness and preserving vision as best as possible. In addition to such eye diseases, a visual field defect can also be caused by a migraine attack or stroke, as well as a brain tumor or brain aneurysm. A visual field defect can also be the result of an accident with severe head injury. In the case of visual field loss, the underlying disease determines the therapy. If restoration of previous vision is not possible or only possible to a limited extent, the physician will endeavor to work out solutions with his patient for the best possible compensation of the impairment.
Treatment and therapy
The underlying disease leading to visual field loss determines the therapy. Possible measures include prescribing visual aids or medications, as well as neurosurgical interventions. Often, however, visual field defects cannot be reversed, so that in this respect a restorative therapy is not possible. Especially in the case of age-related visual field loss such as macular degeneration, treatment attempts often do not achieve the desired success. In case of cataract the clouded lens is removed. Glaucoma is usually treated conservatively at first with eye drops, but also with laser therapy if necessary. Often this does not lead to a lasting reduction in intraocular pressure, so that surgery must be performed to drain the pressure-triggering aqueous humor. As an immediate measure for acute intraocular pressure increases, medication is administered before surgery is performed immediately afterwards.In the case of sudden events (such as a stroke or cerebral hemorrhage caused by external force) that lead to a loss of the visual field, a visual field loss that has occurred can possibly be reversed with early therapy. In the case of a stroke, an attempt is made to dissolve any blood clots in the brain by administering medication (thrombolysis). Furthermore, drugs are given to inhibit blood clotting so that vessels do not become further clogged. Cerebral hemorrhages require immediate surgery. Aneurysms, which can also lead to visual field loss, are treated conservatively with antihypertensive medications or surgically, if necessary.
Outlook and prognosis
A common cause of visual field loss is retinopathy, damage to the retina that occurs with age after the age of 60. If left untreated, this impairment of central vision leads to cataracts due to clouding of the lens of the eye. Glaucoma is called glaucoma and is due to increased intraocular pressure. The optic nerve is damaged and the patient goes blind in the worst case. The prognosis varies. Depending on how far the visual field loss has progressed, countermeasures range from medications to visual aids to neurosurgery. In many cases, visual field loss cannot be reversed. In the case of age-related retinal damage (macular degeneration), therapeutic success often does not occur as desired. Patients suffering from cataract or glaucoma usually have a positive prognosis, because these visual disorders can often be successfully treated by removing the clouded lens or by administering eye drops to reduce intraocular pressure. Laser therapy also increases the chances of recovery. In the case of an acute increase in intraocular pressure, the prospects are positive in the further course of the disease, as therapy is provided by medication and subsequent surgery. Sudden events such as a stroke, traumatic brain injury, cerebral hemorrhage or aneurysm can also be causes of visual field loss. In these acute cases, the prognosis depends on prompt treatment, because the sooner countermeasures are taken, the better the chances of recovery.
Prevention
Preventive measures are not possible for purely age-related visual field loss, nor for cataracts. The risk of visual field loss in the form of glaucoma can be limited by regular measurement of intraocular pressure, especially after administration of cortisone-containing medications and after injury. Aneurysms can be partially prevented by abstaining from nicotine consumption and by avoiding excessive alcohol consumption, which increases blood pressure. High cholesterol and obesity also increase the risk of developing an aneurysm or stroke, while physical activity lowers the risks of suffering a visual field defect.
Here’s what you can do yourself
Visual field loss, also called scotoma, is a symptom in which vision fails significantly or partially. In the worst cases, this can lead to complete blindness. In any case of visual field loss, the doctor must be consulted immediately. This is especially true if it fails for the first time or acutely, if it increases significantly, if perception is limited to small outlines, or if it is accompanied by symptoms such as nausea and headaches. Unfortunately, it is very rarely possible to treat a scotoma and to take one’s own measures is therefore all the more difficult. The reason for this is that it is an irreversible disease, so the symptoms can only be slightly weakened. By taking medication or using visual aids, the scotoma can be prevented from getting worse. Furthermore, measures can be taken to make daily living with scotoma easier. This includes magnification of keypads and fonts on screens, voice-activated devices, programs that allow articles and books to be read aloud, and magnifying glasses in the case of visual and reading difficulties. Thus, it is important to avoid further complications and difficulties in everyday life under any condition, and the above measures should help. In case of eye pain and physical discomfort associated with the visual field loss, only pain-relieving medications can be taken.
