The pupil gets bigger and smaller to control how much light your eye is exposed to. We also have these muscles in our eyeball called ciliary muscles. Ciliary muscles surround the lens and hold it in place. When the muscles relax they pull and flatten the lens so that the eye can see objects that are far away. To see the closer objects the lens must thicken. Inside the retina are light sensitive cells that come in two main different forms which would be the rods and cones. The cones help your vision in the poor light and rods help sharpen your central vision. (Former 2016) Vision for non-human primates works a little bit differently than human vision because it varies. Sometimes you see primates in the same species even who have different vision perceptions than other members of their species. Most humans, apes and old world monkeys are trichromatic which means they see three colors. This is very helpful for most primates except nocturnal ones because they would still need the daylight to really see the colors. The cones in their eyes allow them to see different blues, greens and