When your iris changes in size from light why does does the area we can see not change?

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When your iris changes in size from light why does does the area we can see not change?

In: Biology

Your eye only sees a tiny dot clearly at any one time. It moves around quickly to get a bigger view and your brain stitches it all back together for you.

Let’s call them points. Every tiny point on the area of your iris all projects the same full image on your retina. The more points, the more of these full images overlap, making it brighter.

The size is mostly about focusing not picture size, so it’s like wearing glasses. You are always seeing generally the same image, but the quality and focus of that image is what is shifting

It’s because the retina — where light is processed into signals for the brain — it’s kind of like a movie screen — is not immediately adjacent to the iris.

If the retina were adjacent to the iris, then yes, a smaller iris aperture would mean a smaller field of vision.

But light hits the retina (the curved movie screen) pretty much all over whether the iris aperture is tiny or large, because the retina is a centimeter or so away from the aperture.

the light coming in from the very side of your vision when your pupil is small can still make it onto the back of your eye (the retina) so you don’t notice the change. Also, there are fewer light sensitive cells way out on the sides of the retina so you wouldn’t notice subtle changes like you would in the middle of your vision.