Loss visual field: signs of symptoms and causes

2021-01-26 12:00 AM

The lost visual field is detected in the hospital bed by the comparison method. Examination of two people at the same time is clinically useful when parietal lobe damage is suspected.

Description

A lost visual field is a reduction in a normal market share. The normal field of view (in the upright position) is about 90 ° towards the temple, 50 ° in the top, 50 ° in the nose, and 60 ° down.

The lost visual field is detected in the hospital bed by the comparison method. Simultaneous examination of two people is clinically useful when suspecting parietal lobe damage to detect a loss of perception of one side of the market. In this condition, the patient can perceive an object moving in the left side of the field during turn stimulation, but cannot perceive the object when stimulating both markets simultaneously.

Causes

Often met

Posterior cerebral infarction.

Infarction in the middle cerebral artery.

Occipital haemorrhage.

Age-related macular degeneration.

Less common

Retinitis pigmentosa.

Giant pituitary adenoma.

Cystic cranial tumour.

Clogged central retinal artery branch.

Scattered fibrosis.

Figure. Normal visual field breadth

Figure. The mechanism of the lost visual field is high. 

Branch occlusion of the central retinal artery; retinal detachment; damage to a part of the optic nerve.

Figure. The mechanism of the lost visual field is the central point. Macular degeneration; damage to the optic nerve.

Figure. Mechanism of the lost visual field is shrinking.; retinitis pigmentosa; 

central retinal artery obstruction does not affect the retinal artery - mi; Chronic papular oedema.

Figure. The mechanism causes the loss of the two-sided semi-temporal market. Vision interference.

Figure. The mechanism causing loss of market selling heavily co-branded. 

Damage to the visual cortex; damage to the upper and lower rays; lateral knee injury, thalamus; damage to the visual strip (least common).

Figure. The mechanism that causes the loss of the peer-to-peer market does not affect the gold point. Damage to the occipital lobe.

Figure. The mechanism causing the loss of the market to sell well known 1/4 under. Damage to vision.

Figure. Upper retinal infarction (pale area) because retinal artery branch obstruction, causing high focus

 

Figure. Arterial surgery to supply blood to the anterior segment of the optic nerve

 

Figure. Mechanism of the lost visual field

 

 

Sensitivity

Specificity

LR is positive

LR is negative

Strong sale

30%

98%

NS

0.7

Board. The clinical benefit of haemophilia in unilateral brain damage

Mechanism

The causes of the lost visual field are classified as follows:

Structural disturbances before interference.

Visual interference disturbances.

Post-interference structure disturbances

In general, the loss of vision across the longitudinal meridian (the line that divides each field into two halves) is caused by pre-interference damage or primary eye diseases. A vision loss that does not cross the longitudinal meridian, eg, in the quadrilateral hemisphere, is caused by damage at the intersection or after visual interference.

Disorder before visual interference

Pre-interference disorders cause the loss of unilateral vision, which can cut across the longitudinal meridian (also known as the line dividing the field of view).

Hyper emporia - obstruction of the central retinal artery branch

Clogging of the upper or lower central retinal artery can cause infarction of the upper or lower half of the retina, leading to a high or lower focal point.

Shrink field - occlusion of the central retinal artery does not affect the retinal artery - the eyelid.

The retinal artery - the eyelid supplies blood to the central indent and macular (for example, the central part of the field of view). Central retinal artery occlusion does not affect retinal arteries - the eyelid causes retinal infarction, except for the central part, leading to a shrinking field.

Shrinking market - retinitis pigmentosa

The most common form of retinitis pigmentosa causes gradual loss of photoreceptors of the peripheral retina rods, resulting in poor vision in low light and loss of peripheral vision (or also known as a shrinking market).

Central affliction - optic nerve disorders

The area of ​​the optic nerve entering the retina corresponds to the location of the physiological blind spot because there are no photoreceptors in this area. Neurological disorders can cause the spread of physiological blindness and/or central focal point.

Central dark spots - macular degeneration

Macular disorders are mainly caused by damage to the retina in the central fovea and the peristomal fossa. The central hole is the place with the greatest concentration of rod cells and the highest convergence in a fixed position (also known as the central area of ​​the market).

Damage at visual interference

Damage to the visual intersection causes dysfunction of the nerve fibres that govern the central retina, thus causing the temporal hemispheres. Damage to the visual intersection is mainly the result of compression from a nearby mass. The most common cause is a giant pituitary adenoma. Other causes include cranial tumours and pituitary haemorrhages.

Signs accompanying damage at the visual interference include hypothalamic-pituitary axis disorder, headache and hydro encephalopathy.

Disorders after visual interference

Post-interference disorders cause a decrease in the homologous market. Nerve fibres from the cortex, optic ray, and lateral axillary body of the thalamus contain fibres that govern the parietal temporal retina and the opposite central half retina. The fibres that govern the opposing half of the retina cross at the visual interference.

Selling heavily at the same name does not affect the gold point

The occipital lobe injury does not affect the posterior primitive visual region, which contains nerve fibres that reach the macula and the central fovea, which can cause semi polarization without affecting the macula. The central hole and macula make up a small proportion of the entire retina, but they are provided with a large number of nerve fibres. Because of such a large number of fibres, incomplete occipital lobe injury provides enough nerve fibres to protect the central market.

Meaning

In detecting a market decrease of a pre-interference origin, the comparison method has a sensitivity of 11-58%, a specificity of 93-99% and an LR = 6.1.

In detecting a market reduction originating at and after visual interference, the comparison method has 43-86% sensitivity, 86-95% specificity and LR = 6.8.

Refer to the table for clinical benefits of the hemisphere in unilateral hemisphere injury.

 

Sensitivity

Specificity

LR is positive

LR is negative

Strong sale

30%

98%

NS

0.7

Board. The clinical benefit of haemophilia in unilateral brain damage.