INTERNAL STRUCTURE OF THE EYE
Conjunctiva: thin, clear layer that covers cornea – protects the cornea/eye. Has pain
receptors that cause eyelids to close when a foreign body is about to enter
Cornea: thin, clear (no blood vessels) front part of sclera. Allows light rays to pass
through to the light sensitive cells. Refracts these light rays – focuses them onto the
retina.
Sclera: tough, thick, white sheath that protects inner parts of the eye – “white of the
eye”. Its inelastic nature helps maintain the shape of the eye.
Pupil: small opening in the iris - allows light to strike retina
Iris: controls the amount of light entering the eye by controlling the size of the pupil. Has
radial and circular muscles (antagonistic muscles – when one contracts the other
relaxes). Radial muscles contract (dark) – pupil gets bigger (more light enters). Circular
muscles contract (sunny) – pupil gets smaller (limits light entering).
Ciliary body: extension of the choroid, contains circular ciliary muscles. Produces
aqueous humour. Control curvature of the lens during accommodation (which changes
the shape of the lens when your eyes focus on a near object)
Conjunctiva: thin, clear layer that covers cornea – protects the cornea/eye. Has pain
receptors that cause eyelids to close when a foreign body is about to enter
Cornea: thin, clear (no blood vessels) front part of sclera. Allows light rays to pass
through to the light sensitive cells. Refracts these light rays – focuses them onto the
retina.
Sclera: tough, thick, white sheath that protects inner parts of the eye – “white of the
eye”. Its inelastic nature helps maintain the shape of the eye.
Pupil: small opening in the iris - allows light to strike retina
Iris: controls the amount of light entering the eye by controlling the size of the pupil. Has
radial and circular muscles (antagonistic muscles – when one contracts the other
relaxes). Radial muscles contract (dark) – pupil gets bigger (more light enters). Circular
muscles contract (sunny) – pupil gets smaller (limits light entering).
Ciliary body: extension of the choroid, contains circular ciliary muscles. Produces
aqueous humour. Control curvature of the lens during accommodation (which changes
the shape of the lens when your eyes focus on a near object)
