The sense of sight is one of the most developed and important for the human being. Although it is not impossible to live without this sense (as the many people who live their lives with blindness deserve), its absence is a major difficulty when it comes to relating to the world, especially if the blindness is not of birth but acquired.

There are many types of blindness, with different characteristics and causes. One such type is cortical blindness , which will be discussed throughout this article.

Cortical blindness

We call cortical blindness, more recently called neurological visual impairment , to the alteration or pathology in which there is a loss of vision in both eyes due to bilateral involvement of the occipital lobes.

The eyes and the nerve pathways that receive visual information function properly, even if the pupils react to nerve stimulation, but this information is not processed in the brain because of the damage to the fibres in which it would usually occur. Thus, the subject does not see because his brain does not register the visual information . It is possible that although the subject is not able to process the visual information, he or she may experience visual hallucinations.

There may also be some collusion, imagining what could be seen (without being aware that what is described is not a real vision but a construction of its own). Also, something that is often very striking is the fact that some subjects with cortical blindness are not aware of vision loss, presenting anosognosia.

Although strictly speaking cortical blindness would indicate the complete absence of vision, the truth is that its new name (neurological visual impairment) includes this and other situations in which there is a loss of partial vision. Although it is called blindness, in some cases, the subject is capable of perceiving some minimal stimulation, such as light . It is possible that in some cases the blindness may not be perceived externally, as some are able to avoid tripping or bumping into objects due to such processed information remnants.

It can occur at any age and for a variety of reasons.

Possible causes

The direct cause of cortical blindness is the presence of lesions at a bilateral level in the occipital lobes , not being able to process the visual information coming from the visual system. Such injury is usually caused by the existence of a stroke in that area or in the vessels that irrigate it.

The presence of anoxia or certain viral and neurological diseases can also lead to cortical blindness. Another aetiology can be the suffering of cranioencephalic traumas that destroy both occipitals. Intoxications and tumours (the latter, either because they directly affect the occipital or because they generate compression against the wall of the skull in that region of the cortex).

Finally, cortical blindness can also be observed in subjects who do not have said lobe or who have it dysfunctionally, as in some malformations produced during gestation .

Seeking treatment

Cortical blindness has no specific treatment, since it is the result of the destruction of the brain elements that allow visual processing. The exception would be those cases where its cause was a dysfunction of the occipital cortex generated by some treatable cause, such as an infection, as long as the brain tissue has not died.

In addition, in cases where there is a perception of brightness it is possible to perform different types of training to strengthen this capacity and use it in an adaptive way in daily life. Depending on the degree of affectation, a certain improvement (especially in children, with greater brain plasticity), and even a recovery, could occur in these cases. However, generally when there is complete loss of vision this will remain.

Loss of vision or lack of it can have a severe impact on the person who suffers from it and may require psychological intervention. Psychoeducation will be necessary to understand and accept what has happened , what the patient is going through and the consequences it will have on his/her daily life. Not only in the patient, but it is also advisable to carry it out on the immediate environment. It is necessary to provide guidelines for action and advice on the steps to be taken next. Psychotherapy may also be necessary to treat adaptive and emotional problems.

On a functional level, the use of external aids, such as white canes or support canes for the blind and/or guide dogs, may be necessary. Learning Braille and using adapted technology also makes life easier for blind people. Likewise, it is necessary to adapt urban elements such as traffic lights, as well as adapt education or different job positions in such a way that their disability does not imply a handicap .

In principle, there is no solution for cortical blindness, but research has made it possible to develop mechanisms that stimulate the brain regions responsible for processing visual information. It could be possible to reactivate or make connections between non-injurious areas of the occipital that would allow the processing and partial functioning of vision.

Bibliographic references:

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