When light enters the eye it first enters through your cornea, the transparent protective coating over your eye. Next it will pass through the pupil which is the small opening in the middle of your iris, or colored part of your eye. The muscles in the iris help to protect the eye by expanding and contacting based on the brightness of the light in your environment helping you see much clearer in bright and dim light. In side the pupil the light will then move through the lens which focuses the light and displays and image onto the retina, the light-sensitive inner lining of the back of the eyeball. The lens is what enables us to focus on images up close, middle range, and far away. Normally the lens is focused on middle range objects, but when you would want to see something far away or up close the muscles around the lens help with that. To focus on something far away the muscles work to flatten the lens and then to focus on something up close the muscles contract to make the lens as round as possible. On the retina directly behind the lens there is a depressed spot called the fovea. This is the center of your visual field and this is where images are in the most focus. There is also another spot on your retina in which you see nothing this is called your blind spot. On your retina are these receptor cells responsible for vision and they are your rods and cones. The rods respond to varying degrees of light and dark, but not to colors, mostly provide your night vision. The cones allow us to see color as well as light and dark, but they primarily operate in daytime as they are less sensitive to light than the rods are. Inside the fovea is the most concentrated amount of cones with no rods explaining how this is the best focus part of your retina. Right outside the fovea is where the most rods are located with few cones and as you continue to the edges of the retina there are few rods and barely any cones. The rods and cones then connect to these specialized neurons…
