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

Question

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

In: Biology

Answer 1

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.