Does the size of the iris or pupil matter to how good your vision is?

it can. the pupil has the ability to change size, but if youre iris muscles are weak, you can have trouble focusing. the purpose of the pupil/iris is to control the amount of light that is allowed into the eye so as to maintain a steady level of light exposure on the retina. if you have too much light allowed in, you become blinded and overstimulated, and too little light wont allow for enough stimulation.



if you have astigmatism, excess light can increase the severity of your condition. this is due to the fact that a larger pupil allows more room for light rays at improperly reflected angles to enter your eye and appear on your retina as a fuzziness. you can try this yourself if your eyes are slightly poor. poke a pin hole in a cardboard box or construction paper and look through. the small diameter of the simulated pupil makes it so only rays that are already mostly parallel to be allowed into your eye.

Does the size of the iris or pupil matter to how good your vision is?
The iris changes size as it needs to. When there is little light it will expand, by the use of muscles, so as to allow more light in, making it easier for your eye to pick things up. It can also contract, becoming smaller, this is so the eye isn't damage by to much exposure to light. The pupil is simply the black "hole" in your eye. It is the iris that controls the size of the pupil in becoming big and smaller. Therefore it is very rarely to do with the pupil that someone has bad eye sight!