Hemianopsia: types, symptoms, causes and treatment.

A rare neurological disorder in which half of the visual field of one or both eyes disappears.

Hemianopsia is one of the neurological disorders that show us to what extent vision is a complex to what extent vision is a complex functioning process.. We normally believe that what we see enters through the eyes in the form of light and is represented in the brain as a unit, after our nervous system has taken care of unifying the information received in "raw" format.

However, the sense of sight is at work in a process that is not limited to collecting data and putting them together, but has a much more active role than it seems: it composes images that are not actually the same as what the eyes capture.

In fact, the mere fact of having a pair of these sensory organs already makes this necessarily so, and hemianopsia helps us to understand this.. Let's take a look at it.

What is hemianopsia?

As far as we know, vision is one of the most important senses we have, but it is also true that it can fail in many different ways. Hemianopsia is one of them.

As its name suggests, hemianopsia has to do with the hemispheres, or rather, the hemifields, which are the sides of our body divided by a vertical axis (i.e., the left or right sides) as far as our nervous system is concerned. Specifically, hemianopsia is the blindness in relation to one side of the visual field..

In other words, it is not that we do not see out of one eye and as a consequence our visual field is narrowed in the horizontal direction because one of its sides is reduced; it is that in one of the two eyes, or in both of them, one of the two halves of the visual field has ceased to exist.

Symptoms

Hemianopsia may seem unusual and is not as easy to understand as conventional blindness, but it is in fact a neurological disease that affects vision. Consequently, all its associated symptoms have to do with this kind of problems: orientation problems, confusion due to not finding a space, person or object, sensation of not knowing where one is.feeling of not knowing where one is, etc.

It is also possible that these symptoms are mixed with those of the accident or disease which in turn has caused hemianopsia, which as we shall see can be caused by a wide variety of phenomena.

However, these symptoms also depend on the type of hemianopsia in question, as this disorder appears in different ways.

Types

The main types of hemianopsia obey a first fundamental classification: unilateral and bilateral hemianopsia. In the first case, the alteration only affects one of the eyes, while in the second, it manifests itself in the vision that depends on both eyes.

In turn, bilateral hemianopsia can be homonymous, if the affected side in both eyes is the same, or heteronymous, if in each eye the affected side is the same.if in each eye the affected side is different: in one eye it affects the right, and in the other, the left.

Causes

Normally, hemianopsia is caused by lesions originated by trauma, cerebral infarcts and tumors, all of which structurally affect the right side of the eye.all of which structurally affect the nervous system.

However, in some cases it may be due to transient phenomena such as substance abuse or Migraines with aura, which may generate temporary hemianopsias, with very rapid remission of symptoms.

The parts of the nervous system that are usually behind hemianopsia are the optic chiasm or the last sections of the optic pathways on their way to the thalamus: the optic ribbons.

Difference with hemineglect

It is possible to confuse hemianopsia with hemineglect, a neurological disorder that also involves the hemifields.

The main difference between the two is that in hemineglect, not only vision is affected, but also the experience of all the senses.but the experience of all the senses.

The second important difference is that in hemineglect the problem is not technically in the vision itself, but rather in the attention. Sensory data reaches the brainbut they are not processed as if they were relevant: they are "discarded". Therefore, it has been seen that there is a kind of very meager notion of what happens in the ignored hemibody although this information does not pass to the consciousness and the person believes not to have noticed anything, as it has been seen in experiments.

Treatment

In the case of transient hemianopsia, intervention is limited to ensuring the person's well-being until the effects pass. The treatments aimed at intervening in non-transitory hemianopsia are of the type of neurological rehabilitationassuming that complete recovery is not likely to occur.