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That's neat. I wonder if the pupil is actually changing size, or if it's the changing shape of the lens that is making it appear so. If you look into a camera l
by monitron 5y ago
That's neat. I wonder if the pupil is actually changing size, or if it's the changing shape of the lens that is making it appear so. If you look into a camera lens as the focus is changed, the inner parts of the camera do appear to change size.
- drewzero1 5y agoThe eye's lens is behind the iris (unlike a camera which is typically the other way around), so the optics shouldn't affect the apparent pupil size.
- monitron 5y agoWhoa. I had no idea. Thanks for informing me! That's so weird. I had always assumed that the curved front surface of the eye was the lens.
- uj8efdkjfdshf 5y agoYou're not wrong - the cornea (front of the eye) has about 3x the refractive power of the lens. Both function as converging lenses, and the only difference is that the refractive power of the lens can be changed.
- SomeHacker44 5y ago...until age 45 to 50ish, when the lens hardens into a focus close to infinity and you start to need reading glasses. (presbyopia)
- uj8efdkjfdshf 5y agoIt's the accommodation reflex [0] at work here - pupillary constriction goes hand in hand with a shortening of the focal length of the lens, and the eyes also converge together. This is a brainstem level response, so I doubt there'd be any easy way to dissociate these movements consciously. [0] https://en.wikipedia.org/wiki/Accommodation_reflex https://en.wikipedia.org/wiki/Accommodation_reflex
- msdrigg 5y agoInteresting, this makes sense. Thanks for figuring it out