structure of eye

• • Conjunctiva: transparent membrane that lines the inside of eyelids. It protects and lubricates the eye
• • Sclera: opaque tough layer of connective tissue that surrounds and protects the eye. Also, helps maintain the spherical shape of the eye and allows the attachment of external muscles to move the eye
• • Cornea: Transparent outermost front layer of the eye that covers and protects the iris and pupil. Allows light to enter the eye, and directs and refracts light through the pupil into the lens.
• • Iris: A ring of coloured muscle that gives the eye its colour. The muscles contract or dilate to control the size of the pupil and regulate the amount of light entering the eye.
• • Pupil: opening in the centre of the iris that changes size to allow entry of light into the eye
• • Lens: biconvex, transparent structure that can change shape to change the refraction of light to focus light on the retina
• • Ciliary body: consists of ciliary muscles and suspensory ligaments that encircle and hold the lens in position. Also, allows adjustment of the shape of the lens
• • Aqueous humour: transparent, water-like fluid between the cornea and lens. It refracts light and provides nutrients for the cornea and lens
• • Vitreous humour: transparent, jelly-like between the lens and retina. It refract light onto the retina, helps maintain the shape of the eye and contains nutrients
• • Choroid: A layer of tissue between the sclera and retina that is rich in blood vessels. It provides nutrients to the retina, and stops the internal reflection and scattering of light in the eye. 
• • Retina: Thin layer containing photoreceptors at the back of the eye that detects light and converts it into electrical impulses. 
• • Optic nerve: a nerve that transmits light information as electrochemical impulses to the brain to be interpreted