The eyeA window

Structure choroidBlack to absorb lightciliary muscles

Changes the shape of lensconjunctiva

protects the corneacornea

Transparent to allow light

lensBends the light onto the retina

irisControls light entering the eye

suspensory ligaments

Holds the lens in place

scleraTough to keep shape of eye

retinaContains light sensitive cells

optic nerveTransports the impulses to the brain

foveaMost sensitive

part, clear image is produced

Blind spot no sensitive cells

Focusing light onto the retinaThe light rays are bent at the cornea and

the lens.

Pupil reflex

• In bright light:• radial muscle relax and

circular muscles contract to narrow the pupil. less light enters the eye.

• This protects the retina from damage.

• BRRCC

• In dim light:• radial muscle contract

and circular muscles relax to widen the pupil. More light enters the eye.

• This helps a person see better in the dark.

• DRCCR

Accomodation

Accommodationlooking at far/distant objects•The ciliary muscle relaxes•The lens is pulled into a thin shape•This bends the light slightly •The image is formed on the retina

Accommodation

looking at close/near objects•The ciliary muscle contracts•The lens becomes rounder•This bends the light greatly •The image is formed on the retina

Can you tell why your eyes feel tired When you’re reading for a long time?What can you do to rest your eyes?