L'hemianopsia is a visual disorder that causes the loss of half of the visual field.
There is talk of lateral hemianopsia (vertical) if the loss affects the right or left half of the eye; of altitudinal hemianopsia (horizontal) if the loss affects the upper or lower half. Visual field defects of this kind occur when the optical pathways, i.e. the nerve structures that transmit visual information from the eye to the cerebral cortex, are altered and/or compressed.
Depending on whether the lesions occur in front of, in line with or behind the optic chiasm, i.e. the point where the optic nerve of the right and left eye cross, lesions are distinguished into:
-prechiasmatic;
-chiasmatic;
-retrochiasmatic.
In addition, alterations to nerve structures can lead to two different types of hemianopsia:
-heteronymous, when the loss of the visual field affects the outer or inner halves of the visual head;
-omonima, when the loss of the visual field affects the right or left halves of both eyes.
Causes
Hemianopsia can be congenital in nature, but most often it is a consequence of the presence of certain pathologies and for this reason it is considered more of a symptom than a pathology per se. In particular, the most frequent causes of visual field loss are:
-brain ischemia;
-carotid artery aneurysm;
-pituitary gland tumour;
-ictus;
-infections;
-surgical interventions.
Consequences on quality of life
Visual field defects involving partial loss of the visual field can lead to psychological effects and negative emotional effects on the affected person. In fact, sufferers of hemianopsia have difficulty in performing normal daily activities, such as reading or driving. In particular, if the right visual field of the eye is damaged, the subject loses the ability to read quickly to the right of the page, i.e. in the direction of the writing, which results in a marked slowdown in reading; if, on the other hand, the left half is affected, it becomes more problematic to read the next line.
Therapy
These visual disorders, although debilitating, tend to improve in 50% of cases within the first month and in 38% of cases the homonymous hemianopsia resolves spontaneously. Individuals with this disorder can undergo various types of rehabilitation involving eye exercises to compensate for or recover the visual impairment. However, theThe only decisive therapy for hemianopsia is the elimination of its cause.
Source
Dr. Carmelo Chines
Direttore responsabile