INJURY TO THE VISUAL PATHWAY

Synonyms in a broader sense

Optical path lesion, optic nerve, chiasmal lesion, optic nerve

introduction

The visual pathway begins at the retina of the eye and directs the visual sensations into the visual cortex of the cerebrum.

Various failures occur along the visual pathway. Depending on the location of the damage to the visual pathway, different symptoms appear.

The various failures

Chiasm syndrome
Damage to the visual tract (tractus opticus)
Visual field deficits when the visual pathway is damaged

Chiasm syndrome

In the course of the Visual pathway it comes in the field of Pituitary (Pituitary gland) to a partial crossing of the two optic nerves.
Disorders in this area are known as chiasm syndrome and are expressed through typical symptoms and complaints.

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You can find more about this under our topic: Chiasm syndrome

Damage to the visual tract (tractus opticus)

All damage that lies behind the optic nerve junction (chiasma opticum) have homonymous visual field defects to result. Homonymous visual field defects are designed in such a way that either the right or left half of the Facial field fails. This is because the fibers that run in the optic tract already contain crossed fibers from the opposite side. Often it comes to the loss of nerve fibers of the optic nerve.

Damage behind the switching point in the midbrain

A cause of an injury to the visual pathway can e.g. be a stroke.

Here is often the one Visual radiation, but mostly the Visual cortex affected.

causes
The most common cause is a stroke (Apoplex). A stroke is an infarction of the visual cortex. This area responsible for conscious seeing is no longer (sufficient) with blood provided. A Infarct arises due to a vascular occlusion and the resulting lack of oxygen supply to the brain in the supply area.
In the case of a visual impairment, it is most likely that Media cerebral artery or posterior (middle and posterior cerebral artery) affected. These are arteries that supply the rear part of the cerebrum, in which the visual cortex is located.

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Symptoms / complaints
Similar to damage to the Optic tract (Visual trajectory) homonymous (located on the same side) visual field deficits can occur. The distinguishing feature is that there is no atrophy of the optic nerve. There is also no pain.

therapy
If necessary, the vascular occlusion is through Medication tried to fix. This only works if no more than 3 hours have passed since the event. Without treatment and definitely with treatment (lysis = dissolution of the Blood clot) damage to the brain area remains.

Visual field deficits when the visual pathway is damaged

For lesions (damage) of the optic nerve (optic nerve) goes blind eye completely if the entire nerve is affected. The other eye continues to see normally regardless of this. Pupillary disorder also occurs.
If there is damage (lesion) in the Optic tract homonymous hemianopsia occurs. This is a certain form of visual field loss. There are retinal areas on one side and the corresponding halves of the field of view. If the right tract fails, the right halves of the retina in both eyes and thus the left half of the field of vision fall out. The complete failure only occurs if the tract is completely damaged. Otherwise the failures can vary and do not always have the same shape in both eyes.
If there is a failure of the visual cortex (Center of vision in the cerebrum), i.e. part of the cerebral cortex, there is also a homonymous hemianopia. The left and right eye failures have exactly the same shape here. So they are congruent.

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