In common, the layers of the eyes can be classified into three main layers. In details, the first layer is cornea and sclera, the second layer is the iris, choroid and ciliary body. And the third layer is the retina. And the cornea can allow light to enter the pupil and hit back of the eyes so that you can have the sense of sight. And the three muscles of the second layers are work together. they can control the amount of light that passes through the lens of your eyes. And retina is a complex layers. they can work with with the other layers of the eyes. Also, they can communicate with optic nerve at the back of the eye.
They r separately cornea,sclera and iris.However,u should know that although they r very close to each other but they absolutely work differently.First of all,u need to know that cornea can help ur eyes to get light and which is also usually called ur white of eye.I guess this saying can be very clear to u,huh?As to other two parts of ur eyes,I don't think I know much.Maybe u can find a suitable time to consult ur eye doctor.