6 ms·

Am I understanding this right? The choroid layer behind the retina gets slightly thinner when we look at dark details on a bright background, and slightly thick

by tobr 8y ago

Am I understanding this right? The choroid layer behind the retina gets slightly thinner when we look at dark details on a bright background, and slightly thicker when we look at bright details on a dark background, and somehow this causes an opposite effect in the overall eye growth over time. So spending a lot of time looking at dark letters on a bright background would cause the eye to become too long and unable to focus on objects far away. Is there an explanation for why the choroid changes its thickness, and why this change would create an opposite effect in eye growth over a longer period?

philipswood 8y ago
So, they eye works pretty much like a camera - but it's not a camera: it's a complex dynamic self-assembling, self-tuning adaptive structure. The fact that it's geometry is roughly static around a focal length that has sharp focus on the retina is a wonder of homeostasis with at least three known tuning loops: 1) the lens Moving on swiftly... 2) a slower feedback loop adjusting the choriod (hence focal length) in the order of hours. 3) an even slower loop adjusting the eye geometry over longer periods of time.
- philipswood 8y ago
  The story so far: We hack our visual sense to be a data channel for symbolic information. This incidentally messes with the above homeostatic loops causing myopia. We then hack the eye's optics to correct the immediately problem without fixing the cause and oppose the corrective process by adding glasses or contacts. We end up at a myopic static point where the balance of forces match. Big lens wins.
  - pen2l 8y ago
    This is just so wonderfully fascinating, that's all I have to say!
    - philipswood 8y ago
      Is fascinating - checkout https://www.sciencedirect.com/science/article/pii/S0896627304004933 https://www.sciencedirect.com/science/article/pii/S089662730.... If you want to duckduckgo: Emmetropization

by tobr 8y ago

philipswood 8y ago

So, they eye works pretty much like a camera - but it's not a camera: it's a complex dynamic self-assembling, self-tuning adaptive structure. The fact that it's geometry is roughly static around a focal length that has sharp focus on the retina is a wonder of homeostasis with at least three known tuning loops: 1) the lens Moving on swiftly... 2) a slower feedback loop adjusting the choriod (hence focal length) in the order of hours. 3) an even slower loop adjusting the eye geometry over longer periods of time.

philipswood 8y ago
The story so far: We hack our visual sense to be a data channel for symbolic information. This incidentally messes with the above homeostatic loops causing myopia. We then hack the eye's optics to correct the immediately problem without fixing the cause and oppose the corrective process by adding glasses or contacts. We end up at a myopic static point where the balance of forces match. Big lens wins.
- pen2l 8y ago
  This is just so wonderfully fascinating, that's all I have to say!
  - philipswood 8y ago
    Is fascinating - checkout https://www.sciencedirect.com/science/article/pii/S0896627304004933 https://www.sciencedirect.com/science/article/pii/S089662730.... If you want to duckduckgo: Emmetropization