The Human Eye

Light travels through the cornea and pupil

• Light then goes through the retina

•pupil-controls how much light enters the eye

° iris - the colour part of the eye, controls the pupil

Bright light = pupil contracts (smaller) lens, light enters

Low light = pupil dilates (bigger), more light enters

Light passes through lens and refracts again (converges)

• realits me tie degral senser it a camel the eye)

•sensors in retina converts light energy into electrical impulses sent to the brain via optic nerve

• brain interprets signals as vision

Muscles in our eye (diary muscles), help the eye focus by changing the shape of the lens

• distant object → lens flattens → light bends less

• nearobject → lens bulges → light bends more

Myopia (near-sightness:

• inability to see far objects clearly

• image formed front the retina distance between lens & retina too large

•or corneal lens refracts

•corrected with a diverging lens (or negative meniscus)

Hyperopia (far-sightness):

• Inability to see near objects clearly

• image formed behind the retina

• distance between lens & retina too small

•or cornea/ lens does not refract light enough

•corrected with a converging lens (or positive meniscus)

Myopia: focus point ahead diverging lens

Presbyopia:

• far-sightedness due to loss of accomidation

• age-related, loss of lens elastically

• Corrected with reading glasses (converging lens)