Visual pathways (and hemianopia or hemianopsia)

What are the visual pathways? These are the routes that neurones take from the retina to the visual cortex in the brain. When these neurones are bundled together we can see them as the optic nerve, optic chiasm and optic tract. These first neurones run to the lateral geniculate nucleus and then synapse with second neurones that run to the occipital lobe.

The trick is that some of these neurones from each retina cross to the other side, and some do not. This means that if different parts of the visual pathway are injured, different effects on vision occur.

Let's have a look at the anatomy of the visual pathways to try to better explain this. I'll use some videos to illustrate how visual fields may be lost but these are only to help the explanation and are not an accurate depiction of how vision is affected. For that we'd need 3D video - maybe something to do in VR in the future?


Music by Jahzzar
Album: HiFi City Tales
Song: Bodies
  / jahzzar​​