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Cortical blindness is vision loss caused by damage to the visual portion of the occipital cortex in the brain, resulting in total or partial loss of vision. It can be caused by injury, occlusion of the posterior cerebral artery, or long-term use of anticonvulsants. Symptoms may include hallucinations, denial of blindness, or difficulty perceiving certain objects. When less than total, it is referred to as cortical visual impairment (CVI).
Cortical blindness is vision loss due to damage to the visual portion of the occipital cortex in the brain. Although the affected eye is physically normal and healthy, damage to the brain results in total or partial loss of vision. The pupil of a cortically blind eye dilates and constricts again in response to changes in light, because this reaction is a reflex and does not rely on the brain.
There are many possible causes of cortical blindness. It can be the result of physical damage to the occipital cortex, such as injury. It can also be caused by occlusion of the posterior cerebral artery, which supplies oxygenated blood to the occipital cortex. It’s also a side effect of long-term use of some anticonvulsants, prescription drugs used to treat seizures.
Cortical blindness sometimes presents with hallucinations or a denial of blindness. Some patients with this condition are able to see moving objects, but not stationary objects. In all cases of the disorder, structures in the eye itself, such as the retina and iris, function normally, 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 most often occurs after a stroke, but it can also result from head trauma. In Riddoch phenomenon, a type of cortical blindness, lesions in the occipital cortex cause the patient to lose the ability to see stationary 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 total, it is also referred to as cortical visual impairment (CVI). Symptoms of CVI can include vision that varies from day to day, a discrepancy in vision between the two eyes, a narrow field of vision, and photophobia or aversion to light. If the CVI is worse in one eye than the other, impaired depth perception may result. A patient with CVI may also be able to perceive some types of objects better than others; for example, you may be able to read text, but have difficulty perceiving faces. CVI is not usually associated with loss of the ability to see colors, but some colors, particularly yellow and red, may be easier to see than others.
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