Which part of the eye do we actually see out of? Like if we covered our pupils could we still see a bit with our irises and the whites? And whats the purpose of the iris?
In: Biology
The pupil is the part that lets light through into the eye. We couldn’t see anything if we completely covered our pupil.
Following on from that, the pupil is *only* an opening; the iris is the muscle that controls the size of our pupils.
Thank you guys so much for your knowledge! Also why do irises come in different colours?
The iris, in addition to its light-controlling function, also functions for communication and display- humans are *very* good at telling where other humans are looking based on where the darker dot of the iris is in the eye. And one theory on why blue eyes are somewhat popular is that it’s easy to tell when the blue-eyed person’s pupils are dilated, which is a display of interest.
Light enters your eye from the pupil (after passing through the cornea, the transparent layer) which is “just” a hole. Then the light hits the retina, a special tissue with photoreceptors that transforms light in electrical impulses that the optical nerve can transfer to the brain, responsible of converting those impulses into the images you see.
If you cover the pupil, light in normal conditions can’t hit the retina so your brain won’t get any signal.
The iris is a membrane that controls the size of the pupil, allowing more or less light to enter the eye. Is made of two layers: the upper one, made by the stroma and a sphincter muscle responsible for contorlling the size of the pupil and a lower one, made by pigmented cells that blocks the light, so it can pass only through the pupil.
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