How does the eye know when the image is in focus? There is distance measuring device, only light entering the eye. No outer feedback to be sure that focus is in fact focus not something the eye think is focus.

Question

Thank you all for your respons and upvotes.

I can now see and focus on the answer of my question 🙂

In: 3993

Answer 1

You learn to see. The information that reaches the brain is upside down. Also what the inner half of the eye sees goes to the brain hemisphere on the opposite side. The outer half information goes to the hemisphere on the same side. With fine the brain learns to see; to unscramble the information.

At the beginning the eye doesn’t even focus. It’s focused on one distance. You can see this in infants when you get your face closer and farther away you can tell where that sweet spot is. It’s usually about two feet. With time they learn to focus at different distances.

Because this is a learned skill if a child that needs glasses doesn’t wear them, then if he decides in his teenage years that he wants to wear them to see better, he won’t. Or at least not as well as he would have if he would have worn his glasses early on. This is because the brain didn’t learn want a good image should be.