Scotoma Relative

Relative scotoma (S. relativus) Introduction Scotoma is a visual defect in which there is loss of part of the visual field. This can be caused by various reasons, such as eye injury, corneal disease, or cataracts. However, there is another type of scotoma - relative scotoma, which occurs when the visual cortex of the brain is damaged. In this article we will look at what a relative scotoma is and how it manifests itself in the human mind.

What is a scotoma? Scotoma refers to a defect in visual function that results in deterioration or loss of perception of certain parts of visual space. It is the result of the inferiority of the neurons in the retina and visual cortex of the brain that perceive and analyze light stimuli. Scotomas can have different shapes and sizes, it all depends on how damaged a particular part of the visual system is. They can be absolute, when the perception of a specific color or shape of an object as a whole is disrupted, and relative, when a person sees a gap in the overall picture of vision - a scotoma.

Relative scotomas are divided into groups. With paracentral scotoma (referred to as “central prosopagnosis”), the patient perceives familiar objects in fragments, either their shape, or their shape in the context of color - for example, the patient can recognize a face in a picture if he has retained heightened color perception. Such scotoma is accompanied by the illusion of understanding reality. Also, paracentral scotoma is persistent. Other distinctive signs of a paracentral defect are that in the process of perception, objects lose detail, the color becomes less saturated, and lines disappear. The patient finds it difficult to say exactly how many zones in real life intersect with his perception. Variations in color contrasts sometimes even change the shape of the image (anaglyphs). Symptoms of relative achromatopsia are a frequent accompaniment of paracentral scotomas. Pathogenesis The mechanism of pathogenesis of relative scotoma differs from the mechanism of development of other types of visual defects. It is provoked by the disappearance of the reaction between the cells of the visual cortex and visual zones, which is responsible for the correct color and spatial patterns. Thus, under the influence of a certain stimulus strength, neurons will lose the property of conjugate excitation. Spatial analysis functions fail. In addition, this leads to a loss of the ability to differentiate between images and objects and an inability to put them together into a single real event, so to speak, a lack of a sense of “input”. The loss of color sensation is partially compensated by a decrease in other responses of the visual sphere, but does not lose its character. The function of forming shape and depth goes into “unfilled space” and becomes unavailable for restoration. The deeper and more extensive the zone left by the relative threshold of vision, the more severe the consequences of the disease.