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​​

[@shellybellie132]

I have dealt with visual issues all my life, most recently right homonymous hemianopia. I have never had it explained so beautifully. Thank you

[@bzat2024]

Fantastic !! Mind bending -how it evolved! Complex subject made understood by brilliant teacher 👍🏼

[@basketballfan5763]

I lost sight in left eye suddenly with supposed vasculitis just over a year ago. Double occlusion in central main artery and vein. I thought i would NEVER accustom myself but I did. I have peripheral very little vision around eye at edges and this was more of a hindrance(the blob in centre blinded vision clarity in my right good eye) tho it helps to know if a blue color truck is coming from around a left corner at me!!! It also took me6weeks outa the hospital to see real dimensions again. I could not judge how far away r near objects were ie trees near me on road I thought would hit me in face as I felt they were nearer than they were. Tho edges paths and esp getting on a train was very hard and still is a scary guessing game!! Lots love. I LOVE your vids!!

[@duemiladiciannove9386]

Great job as usual thanks.future autonomous vehicles should copy from that. I's a perfect fault tolerant system. It's unbelievable. we are so complex, everything evolved with great precision.

[@saumyalandge7349]

Best explanation !!

[@ameliadewfall471]

This is the only video I’ve watched on this that has made me understand it, I find hemianopia so interesting, I have an interview to be a senior ophthalmology assistant so I’ve been touching up on conditions I don’t quite understand and this has really helped!

[@udaysatviktripathi1794]

Sam Webster our personal Anatomist 😄✌🏻💯

[@sonia_uc]

thank you so much prof🙏🏽

[@ampfiddler7078]

You are so clear and the best teacher ever !!

[@Sternschnuppen85]

A very complex subject to understand! Thank you for taking the time to help your viewers further learn about this. Always such great explanations!! Appreciated :)

[@danielapetrachi7892]

Wow! I finally understood 🥳🥳🥳 thank you so much, prof Webster!!!!

[@yuta2349]

This was awesome !

[@abdullahrabie3695]

Magnificent ❤

[@emilakimov5249]

Awesome, thanks!

[@rou_dhi]

beautiful

[@palranee5117]

Tank you so much sir, I am just looking for a video like this thank u so much 😇

[@thatwolfyouknow8598]

excellent. thank you

[@sbrebrown]

"Here's a brian." I have seen this a lot in exams too, in the past months :-)

[@SamWebster]

Yep. Me too.

[@MsSemki]

The swan with babies are so adorable!

[@elenaandrew8414]

Cool!!! Thanks

[@andywang5755]

Is the 4th second half filled dark colour be on the right side instead of left side ??

[@dentalexperience6393]

tq :)

[@MandySky]

I have a question. I suffer from occipital neuralgia and cervical dystonia. I had a really bad increase in symptoms lately after my covid shot, with intense migraines. Since then my vision has been weird. Where my words overlap or move it's hard to describe. I'm assuming it's light. But your video was so helpful! 🙏I put an object close to my field of vision so left and right nasal I think you called it. But I can see right through those objects like they are not infront of my eyes unless I start to move them further away from my eyes (so think right and left closest to my nose) so I guess far enough away until the putter parts of my eye vision catches it and compensates I'm assuming. I'm just curious if anyone reads this and has an answer 🤷‍♀️ I'm waiting to see an eye specialist. Thank you for your video 🥰

[@felipec06]

Brilliant video, thank you for that. I have right homonymous inferior quadrantanopia

[@atiaakram6174]

Life saviour :')

[@pritamshil5765]

Sir , Is fear our good friend ? because I felt that it makes me aware of something that I don't know so as to conquer that with adrenaline .

[@user-yj6nb2xl3g]

I love you Sam Webster ❤️♥️☕

[@jakeburroughs841]

How do I contact Sam

[@VladyslavKL]

🦋

[@denise4487]

I have oculocutaneous albinism and my visual pathways cross over

[@A_in_April]

😍😍😍😍

[@katelojarso3215]

I like the videos you make about the human body 😏 its 👍

[@avantikajale7760]

Love 💕 form India

[@kidji6555]

East or best sam web is best❤️

[@shawnli9284]

Dr house

[@adelmohammed9517]

#freePalestine

[@adelmohammed9517]

#PalestineUnderAttack

[@shayurramdutt8267]

A lot of mistakes here.

[@elenaandrew8414]

Can you correct?

[@blessedtvb.m.c1580]

What is the mistake Correct them

[@shayurramdutt8267]

@@blessedtvb.m.c1580 to understand the mistake, we must first do a complete review of neuroanatomy of the eye. Let me know when you want to have the revision session.

[@sadib3215]

If you want to be spoon fed the details and think a complete review of the eyeball is warranted to understand optical pathway this video is not for you. His videos are pretty laid back and sam spares us the boring details we can find in the book ourselves. It's easy to be cynical without contributing anything

[@shayurramdutt8267]

@@sadib3215 you were a mistake