Waxing and waning: AMD and cortical atrophy

8 February 2023
Winter 2023

As age-related macular degeneration progresses, part of the visual cortex starts to atrophy. But which way does the causal relationship work, asks Kim Thomas, and what does it mean for treatments focused on the retina if the brain has entered an irreversible decline?

The visual cortex is at the back of the head, within the occipital lobe and, as Tony Morland, Professor of Psychology at the University of York, explains, it is the “first part of the brain that receives input from the eyes”. Distributed across both hemispheres, it constitutes a map of the information received by our eyes, with input from the right half of our visual world mapped onto the part of the cortex in the left hemisphere, and vice versa. 

We know that conditions such as stroke, traumatic brain injury, brain tumours and dementia can all affect the visual cortex and lead to vision problems or even visual impairment and blindness. A stroke affecting the left hemisphere, for example, may cause vision loss in the right eye, even though the eye itself is unaffected. Similarly, traumatic brain injury can cause field loss, binocular dysfunction and spatial perceptual deficits (Frankowski et al, 2021). A tumour in the occipital lobe can cause loss of vision, visual disturbance and hallucinations. Posterior cortical atrophy (PCA), a rare form of dementia, appears to be caused by damage to the visual cortex. For several years, researchers have investigated the question of whether sight loss resulting from eye disease would be reflected in the visual cortex.

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