Hemianopsia: what it is, disease, symptoms, treatment

By Cristiano Antonino On Apr 28, 2023

Let’s talk about hemianopsia: vision disturbances can be different, temporary or linked to pathologies and in some cases disabling, but only some seriously compromise vision

Among these there is certainly the scotoma but also the hemianopsia, which leads to the loss of partial vision.

What is hemianopsia

When we talk about hemianopsia in the ophthalmological field, therefore, we mean a vision disorder that results in a partial loss of vision, i.e. half of the visual field.

The patient begins to see only with half of the eyes.

The term comes from the Greek, where hemi means half, an means without and opsia means to see.

Even if vision loss affects only half of the visual field, this disorder can lead to serious impairments and problems in everyday life.

In fact, it becomes difficult to read, drive, even walk, because the eye only sees half of the field actually present.

Types of hemianopsia

However, different types of hemianopsia can be distinguished, depending on the factor that triggered the loss of vision and the affected visual field.

As for the field of view, we have:

lateral or vertical hemianopia, when vision is impaired to the right or left
altitudinal or horizontal hemianopsia when the affected half is the upper or lower half

This visual disturbance can then depend on the triggering cause, and therefore we can distinguish between:

homonymous hemianopsia: this means that the loss of vision affects the same side of both eyes, for example the one near the nose in the left eye and the one near the temple in the right eye;
heteronymous hemianopsia: in this case the disorder affects discordant halves of the eyes, and in turn can be binasal, when the parts near the nose experience loss of vision, or bitemporal, when instead it is the parts near the temples

Finally, there is also the possibility of a quadrantopsia or quadrantic hemianopsia, i.e. the loss of only one quadrant of the visual field.

Difference between hemianopsia and scotoma

The scotoma also represents the partial loss of vision, but unlike hemianopsia it usually affects a central point, or in any case it is a spot in front of the eyes in which vision is compromised.

Symptoms of hemianopsia

As it is easy to understand, the main symptom of hemianopsia is linked to the disorder itself, therefore the partial loss of the ability to see.

It can be accompanied by migraine when it causes it, and not a lesion affecting the optics, but it is a rarer possibility.

In general, patients notice the problem precisely because the vision appears to be clearly compromised for half of the visual field, in a symmetrical or specular, vertical or horizontal way.

In reality, hemianopsia itself is to be considered a symptom of other disorders or pathologies, for this reason it is important that it is investigated through an eye examination.

Causes of hemianopsia

There are several causes that can be connected to a loss of half of the visual field, and depending on the type of hemianopsia it is possible to trace the part of the optic apparatus involved.

In more detail, the lesions that can cause hemianopsia are:

median lesion of the optic chiasm, causing bitemporal heteronymous hemianopsia
lesion of both margins of the optic chiasm, triggering binasal heteronymous hemianopsia
lesion of the contralateral right optic tract, which gives rise to left homonymous hemianopia
lesion of the contralateral left optic tract, which gives rise to right homonymous hemianopia
bilateral lesion of optical radiation or visual cortex, resulting in altitudinal hemianopia

What is the optic chiasm

The optic chiasm is the junction point between the optic nerve of the right eye and the optic nerve of the left eye.

It is an oval-shaped structure measuring approximately 8mm by 4 located in the brainstem.

The optical fibers also pass through here, partially intertwining.

Depending on the type of lesion and its location, there may be prechiasmatic lesions, when they affect the section between the eyeball and the chiasm, chiasmatic when they concern the chiasm and retrochiasmatic when they affect the nerve pathways that go from the chiasm to the cerebral cortex.

Diseases causing hemianopsia

As we have said, hemianopsia is the symptom of a lesion affecting the visual system, and more precisely the optic chiasm, the optic tract or the visual cortex.

However, these lesions are in turn caused by other disorders or pathologies which are therefore the real reason why the loss of half of the visual field has occurred.

Among the pathologies most commonly associated with hemianopsia we find:

stroke
meningitis
cerebral ischemia
brain or pituitary tumors
carotid aneurysm
trauma
brain hemorrhages
migraine

Diagnosis of hemianopsia

Since this is a symptom and not a pathology, when you feel the loss of half of the visual field it is advisable to immediately contact an ophthalmologist, so that he can first of all evaluate how the visual impairment looks and then what type of hemianopia we are dealing with .

To do this, the patient undergoes a visual field examination, followed by an eye examination, but there are many other tests that can help to understand the origin of the problem, such as:

fundus examination
optical computed tomography
eye ultrasound
tonometry
retinal fluorescein angiography
Ishihara plates
autorefractory
visual evocative potentials
biomicroscopy
traditional retinography
fluorescence retinography

Given that the cause is always to be found in the nervous system, it is very likely that the ophthalmologist will be accompanied by a neurologist and therefore it will be necessary to investigate further through a neurological visit and special tests, such as a CT scan of the head.

Treatments of hemianopsia

Treating this visual field disorder obviously means first of all treating the problem or disease that triggered it.

In fact, there is no real cure, nor a single treatment, but it depends on the cause that led to the hemianopsia.

In some cases, it is enough to eliminate the cause to totally restore vision and without any consequences, in other cases ocular rehabilitation may be necessary to correctly recover vision.

Hemianopsia is a vision disorder that manifests itself in the loss of half of the visual field in both eyes, caused by lesions that mainly affect the optic chiasm and therefore the way in which the optic nerves of both eyes communicate with each other.

It can be very disabling because it seriously compromises vision but above all it is often a symptom of important pathologies affecting the nervous system, which is why it is essential to go immediately to an ophthalmologist as soon as the field of vision is half obscured.

Since it is not a disease but a symptom, there are no direct treatments to treat hemianopsia but it is necessary to intervene on the pathology or disorder that caused it.

Often, by removing or repairing the problem, the patient regains his or her vision.

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