What is cortical blindness?

Cortical blindness is a loss of vision due to damage to the visual part of the occipital cortex in the brain. Although the affected eye is physically normal and healthy, brain damage leads to full or partial loss of vision. The pupil of cortically blind eye continues to expand and limits in response to light changes, because this reaction is a reflex and does not rely on the brain.

There are many possible causes of cortical blindness. This may be the result of physical damage to the occipital bark such as lesions. Cortical blindness can also be caused by the rear brain artery occlusion, which gives the occipital bark to oxygenated blood. Cortical blindness is also a side effect of long -term use of some anticonvulsants, prescription drugs used to treat epileptic seizures. Some patients suffering from cortical blindness are able to see the movements of objects, but not stationary. In all cases of disorders, the structures of the eye itself work, such as retina and iris, unless separate eye problems are present.

In Anton-Babinski syndrome, a rare symptom of brain damage, named after neurologists Gabriel Anton and Joseph Babinski, the patient is cortically blind, but insists on the ability to see. Anton-Babinski syndrome occurs most often after a stroke, but may also result from head injuries. In the phenomenon of Riddoch, the type of cortical blindness, lesions in the occipital peel cause the patient to lose the ability to see static objects. The patient is able to see movement, but in some cases he cannot perceive the shape or color of moving objects.

When cortical blindness is less than overall, cortical visual damage (CVI) is also called. Symptoms of CVI may include the visual ability that Varyes day by day, irregularity in the visual ability between the two eyes, a narrow field of view and photophobia, or the aversion to the light. If the exercise is worse in one eye than in the other, the depth perception may occur. Patient with CVI can also be capablen perceive some types of objects better than others; For example, it can be able to read the text, but has problems with the perception of faces. CVI is usually not associated with the loss of the ability to see colors, but some colors, especially yellow and red, can be easier to see than others.