This is a strong protective coat for the eye, which is made up of elastic and collagen fibres.
I helps to ensure the shape of the eyeball. It also helps the eye resist external trauma and internal eye pressure , and is used as an attachment base for the eye muscles.
The oclumotor muscles are connected to it.These six muscles help move and rotate the eye. The principal optic nerve travelling from the brain connects to this tissue at the posterior of the eye.
With newborns and very young children this tissue, because it is thinner, may have a slightly bluish tinge, this is due to the underlying pigment showing through. In old age fatty deposits can give the "white of the eye" a more yellowish colour.
Source: The Sclera