A visual field defect is a loss of part of the usual field of vision, so it does not include severe visual impairment of either one eye or both. The lesion may be anywhere along the optic pathway; retina to occipital cortex.

2. The visual field is the full area of what a person can visually see surrounding them.
Visual field loss occurs when an individual experiences damage to any part of his or her visual
pathway, which is the path that signals travel from the eye to the brain. There are many different
causes of visual field loss, and the type of loss depends on what exact part of the pathway was
damaged. Regardless of the cause or type of the loss, the most common symptoms or signs of visual
field loss is blurriness in one’s vision or complete loss (a blind spot) in one’s vision.
However, in many cases, an individual is not even aware that he or she is experiencing visual field loss.
Visual field loss

3. Damage to the visual pathway of the brain can occur due to a
variety of medical reasons, including a stroke, a traumatic brain
injury, tumors in the brain or infections such as meningitis. In some
cases of visual field loss, the damage occurred to the brain while
the child was in the mother’s womb. The amount of loss a person
experiences in his or her field of vision depends on what exact part
of the brain’s visual pathway was affected.
Visual loss following head trauma is common, in addition to direct
injuries of the eye and orbit, traumatic optic neuropathies, carotid
cavernous fistulas, and damage to the intracranial visual pathways
are classic causes of visual loss after head trauma.
Injuryand Trauma

4. OcularPathologies
Cataract
A cataract is a dense, cloudy area that forms in the
lens of the eye. A cataract begins when proteins in
the eye form clumps that prevent the lens from
sending clear images to the retina. Cataracts can
cause unilateral visual field loss on the affected eye.
It happens when there is opacity of the crystalline
lens and deprived the affected eye to be stimulated
by light. This is temporary and visual field can be
restored after cataract surgery. Cataract can be
pathological and can be attributed to the normal
process of ageing.

5. OpticNeuritis
Optic neuritis occurs when swelling or inflammation damages the
optic nerve — a bundle of nerve fibers that transmits visual
information from your eye to your brain. It causes eye pain and
blindness in certain regions of the visual field unilaterally. The
visual field defect in optic neuritis is typically characterized as a
central scotoma. Any damage in the nerves is irreversible.

6. OpticNeuropathy
Optic neuropathy is a term that refers to damage
inflicted on the optic nerve in our eye. This is the
nerve in the back of the eyeball that transfers
visual information from the eye to the brain,
allowing us to see. This condition is one that gets
worse over time, when not treated.

7. Glaucoma
A group of eye diseases that can cause vision loss and blindness
by damaging a nerve in the back of our eye called the optic
nerve. Axons of retinal ganglion cells travel through the optic
nerve carrying visual information from the eye to the brain.
Damage to these axons causes ganglion cell death with resultant
optic nerve atrophy and patchy vision loss. This ocular pathology
can cause scotoma (paracentral) on the affected eye and can
lead to total blindness.

8. OpticAtrophy
This refers to the death of the retinal ganglion cell axons that comprise
the optic nerve. Optic atrophy is the final common morphologic
endpoint of disease process that causes degeneration of axons of the
ganglion cells. Clinically, it manifests as changes in the color and the
structure of the optic disc (cupping) associated with variable degrees
of visual dysfunction.

9. MacularDegeneration
Macular Degeneration is an eye disease affecting
the macula (the center of the light-sensitive
retina at the back of the eye), causing loss of
central vision. With macular degeneration, a
scotoma most often appears in the central visual
field, so it is called a central scotoma.
That's because in dry AMD, the light-sensing cells
(rods and cones) in center of the retina
degenerate along with their supporting cells. It
can be also associated with blurred vision,
distorted vision, dim or eventually loss of color
vision and field of vision.

10. MacularHole
Macular hole is an age-related visual pathology that creates a circular defect in the
central area of the retina (macula). In addition to acuity decline, this condition
generates distortions (metamorphopsia) or blind spots (scotomas) in the central
visual field that are often filled in perceptually.

11. RetinalDetachment
Retinal detachment is an eye problem that happens when
your retina is pulled away from its normal position at the
back of your eye.
A peripheral enlarging area of non-sight (scotoma) is the
classic symptom of a retinal detachment. Superior
detachments associated with an inferior visual field defect
usually progress more rapidly. Untreated, a small retinal
detachment will progress to a total separation of the
retina, including the macula.

12. RetinitisPigmentosa
It is a genetic disease that people are born with, which makes
cells in the retina break down slowly over time, causing vision
loss.
Retinitis pigmentosa (RP) is one of the leading causes of
blindness, and is characterized by night blindness, progressive
visual field defects, and impairment of central vision.
A peripheral ring scotoma (detectable by visual field testing)
widens gradually, and central vision may also be affected in
advanced cases. Vision decreases as the macula becomes
increasingly involved and can evolve to legal blindness.