What Is a Visual Field Defect?
The visual field is the surroundings that can be viewed at any given time by a person. The normal visual field can vary from person to person. However, the average visual field for a person is 50 degrees superiorly, 70 degrees inferiorly, 60 degrees nasally, and 90 degrees temporally. A visual field defect could reduce vision in the following angles. The lesion may cause a reduction in vision but may not entirely lead to vision loss. Visual field defects may also be known as blind spots. The blind spots may be persistent or may be intermittent. These blind spots may be present in a single spot or shifting. The causes of visual defects may be due to various reasons.
What Are the Causes of Visual Field Defects?
The various causes of visual field defects may include. The visual field defects can be due to central or peripheral vision loss.
The various causes of central vision loss may include:
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Wet macular degeneration is associated with aging.
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Macular hole (a condition that affects vision).
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Optic neuropathy( a condition that affects the nerves of the eye).
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Leber’s optic atrophy (a rare condition with visual impairment).
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Other conditions such as best's diseases.
The various causes of peripheral vision loss may include:
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Retinal detachment (a condition in which the retina is detached from the underlying layers).
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Retinitis pigmantosa (a rare condition that affects the retina).
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Glaucoma (a condition in which the optic nerve is affected).
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Brachial retinal artery occlusion (Blockage of the retinal artery).
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Chorioretinitis (it is the inflammation of the uveal tract of the eye).
What Are the Types of Visual Field Disturbances?
The various types of retinal detachment may include:
1. Altitudinal Field Defects: This defect denotes loss of vision in the entire superior or inferior half. However, this type of visual defect does not cross the midline.
This defect can be caused due to conditions such as:
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Retinal detachment.
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Retinal artery occlusion.
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Optic nerve abnormalities.
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Optic disc coloboma (irregular closure of the optic disc).
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Glaucoma.
2. Arcuate Scotoma: It is a bow-shaped visual field defect. This defect follows the shape of the retinal fibers. This defect does not cross the midline. It causes damage to the ganglion.
This defect can be caused due to conditions such as
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Optic disc drusen (calcification of the optic nerve head).
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Glaucoma.
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High myopia (high power or refractive error).
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Ischemic optic neuropathy (ischemia or thrombosis of the optic nerve).
3. Bi-nasal Field Defect: In this type of defect, there is vision loss on both the median sides. The defect does not cross the vertical midline.
This defect can be caused due to conditions such as
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Glaucoma.
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Non-physiologic vision loss (loss of vision that is not caused due to any lesion).
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Bi-temporal retinal diseases (vision loss that occurs due to lesions of the outer temporal lobe).
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Aneurysms (ballooning or weakening of the arterial wall).
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Tumors.
4. Bitemporal Hemianopia: In this type of defect, there is a loss of lateral vision in both eyes. This defect also does not cross the midline.
This defect can be caused due to conditions such as
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It may be caused by chiasmal lesions of the optic disc such as, aneurysms.
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Tilted optic disc.
5. Blind-Spot Enlargement: This type of visual field defect is due to the enlargement of the normal blind spot at the optic nerve head.
This defect can be caused due to conditions such as
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Papilledema (it is swelling of the optic disc).
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Optic disc drusen.
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Optic nerve coloboma.
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Drugs.
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Crescent-shaped optic disc.
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Demyelination of nerve fibers.
6. Central Scotoma: There could be a loss of vision of the central vision.
This defect can be caused due to conditions such as
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Macular degeneration of the eye.
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Neuropathy of the optic disc.
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Atrophy of the optic disc.
7. Constriction of the Peripheral Vision: Due to this defect, the eye's peripheral vision could be lost. The eye's peripheral vision could be so reduced that the person may be spared only minimal vision. The outer part of the vision may be lost.
This defect can be caused due to conditions such as-
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Glaucoma.
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Papilledema.
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Retinal detachment.
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Peripheral retinal disorders.
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Macular degeneration.
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Tumors of the optic nerve
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Optic nerve abnormalities.
8. Homonymous Hemianopia: This type of defect indicates the loss of half of the vision. This could be a loss of the vision's left or right half. This defect does not cross the vertical midline.
This defect can be caused due to conditions such as
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Tumors of the optic tract or disk.
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Geniculate ganglion lesions.
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Lesions of the temporal or occipital lobe.
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Migraine.
What Are the Symptoms of Vision Field Defect?
The various symptoms of visual field loss may include
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Decrease in vision.
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Accidentally bumping into objects.
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Accidents due to visual field loss.
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There could be trouble with reading or writing.
How to Diagnose Visual Field Defect?
The specialist will check the visual fields for each eye independently. This will be finished by requesting that the patient depict any missing or foggy regions. Then, at that point, the patient might be approached to include fingers introduced in various pieces of the visual field. At last, more careful strategies can be utilized to test the visual fields. One normal strategy is a robotized test in which the patient presses a button each time a little glimmer of light is seen. Utilizing the consequences of these various tests, the specialist can more readily comprehend where an issue exists in the visual pathways of the eyes or the brain.
How to Treat Visual Field Defect?
There is no specific treatment for the loss of the visual field. The treatment varies from person to person and condition. There can be a spontaneous resolution in some conditions, even without explicit medicines or treatments. Numerous patients slowly foster systems to make up for the adjustment of their vision by moving their heads and eyes regularly to the impacted side to check the amplified "vulnerable side." Other useful methodologies can likewise be extremely useful. For patients who have difficulty reading, a bright-maker can be used on the left margin to guide and align the eyes correctly. Solid logical examinations do not uphold most unambiguous preparation programs that are planned to extend the visual field. Visual therapy can come in very handy in these cases.
Other likely treatments for visual field defects expect to work on a patient's utilization of unblemished vision or unaffected vision instead of explicitly attempting to reestablish the lost vision. Some low-vision opticians may prescribe special eyeglasses that may help in enhancing vision. This approach has mixed results. However, a few patients think it is helpful. A universally accessible preparation program is accessible that endeavors to work on one's capacity to look through the visual climate utilizing eye development. Patients view this kind of conventional practice as support.
Conclusion
Visual field defect can occur due to various reasons. Different types of eye conditions can affect visual field loss that may affect differently. The diagnosis may aid in finding out the cause of the visual field loss. The treatment of visual field loss mainly involves strengthening the vision that is present rather than trying to retrieve the lost sight. Vision therapy can act as an effective practice in strengthening vision. It is important to obtain medical attention immediately if conditions like black spots are observed. A regular and periodic eye check-up can prevent most of these conditions.
