Human eye

What lens do eyes have

convex lens
upside down real images are projected to the back of the eye and flipped by our brain

cornea

transparent covering
admits light and begins refraction process (little)
keeps foreign objects enter into eye

pupil

adjustable opening in the iris
lets light in to eyes

iris

adjusts pupil size
controls light intensity striking lens

lens

focuses light through vitreous humor onto retina

cillary muscles

relax or tighten
enable lens to change shape for focusing

retina

transforms received image/light that sends electrical impulses from optic nerve to brain

optic nerve

carries signal from retina to brain
where the optic nerve is on the retina = blind spot, no rods and cones

whats in the retina

rods and cones

rod

very light sensitive
respond only to light and dark to help detect shapes

cones

need more light to be activated
comes in 3 different types to detect colour.
red, green, blue

whats near sight

myopia
images focused in front of retina - use concave diverging lens to fix

whats far sight

hyperpia
focuses images behind retina - use convex converging lens to fix