Why does your Iris widens...?

...When you aim a bright light on it? it's weird and scary. Why?

Why does your Iris widens...?
depends on the light. The Iris is the aperture controller of the camera of your eye and the pupil is the hole of this camera with the lens in it.

when in normal ambient surroundings your Iris will widen(pupils Dilate) ..in the dark it is widest which is why the night pics of a cat always result in their eyes seeming very light...

also why you have the red eye capture when you're taking the photos of people in dim light...the amount of time needed for the eye to adjust is longer than that of the flash's time...

if you focus a bright light on a person's eye when they're in the dark you'll find their iris is wide..very wide... but it'll narrow down...also training bright light directly on the eye is harmful which is why when an optician checks the response of your eye he asks you to look at a point far off so that the light isn't falling directly on your eye.

In fact the dark spots you see when you suddenly look into a bright area is because of your eye still reacting to the excessive light and trying to switch from \Rods(which are black and white dark receptors) to cones(which are color receptors).

The maximum dilation area is less in the human eye whereas, due to their being night creatures, cats and dogs have high dilation areas which is why their eyes seem brighter and scarier at night.
Reply:I don't know but why is it weird and scary?
Reply:Your pupils also get bigger when you see something that pleases you...that's weirder than when they do it because of light
Reply:so that it adjusts the amount of light that goes in your eyes, so you don't go blind.
Reply:When that happens you can't feel it. Why would you find that weird and/or scary?



You spend too much damn time in the mirror. (actually, so do I, but I'm looking at other disturbing stuff).
Reply:Your iris widens because your pupil ( that black dot in the center of your iris) is closing up to regulate the amount of light entering your eye. Too much light can blind you.
Reply:It doesn't

It contracts when a bright light is on it. It does that so as to stop the inflow of light.

When there is less light presents it widens to allow more light in.

So you can see better.
Reply:it's because the thing in you're eye can't take that much light at once so it adjusts to get the right amount depending on the brightness of the room... it also adjusts when it's dark...
Reply:the pupil thingy going on vessels contract to light and to drugs