What are our eyes physically doing when we zoom in/out?


The best example I have is, sitting in your car and there’s a spot/drop of water on your windshield. Say you’re looking at it but you can easily and consciously “zoom out” to beyond the windshield and look at the tree in the distance without moving your eyes. Are your eyes physically moving? Or is it a mental thing that changes your focus

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2 Answers

Anonymous 0 Comments

Yes, a physical part of your eye is moving.

Your eye has two lenses in it. There’s a powerful one at the front (called the *cornea*) and a less-powerful one in the middle (called, conveniently, the *lens*). These two lenses work together to focus light properly onto your *retina*, which is the part of your eye that actually does the seeing.

Close-up objects require more focal power – that is, you have to bend the light more – for them to be seen in proper focus. Far-away objects don’t require as much focal power.

So your *lens* (the one in the middle) is actually adjustable. It has muscles around it that can squeeze it to be sharply curved, or pull it to be flatter. When you look at close-up objects, it flexes into a more curved shape to provide more focal power. When you look at far-away objects, it flattens out to reduce the focal power.

You know how when people get old, they start to need reading glasses to look at close-up stuff? That’s because the lens stops being able to flex so hard as you get older. So they need glasses to add a bit of focal power to help out.

Anonymous 0 Comments

[Your eye has a flexible lens in it.](https://webvision.med.utah.edu/wp-content/uploads/2017/08/Fig-1a.jpg) There are muscles in your eye connected to that lens that can contract or relax it, changing how light focuses. When you “zoom in/out”, you’re really just refocusing your lens to make it easier to see different distances.

Extra note: As you age, that lens starts to stiffen, making it harder to focus on things close to you. This is why people tend to need reading glasses as they age