the eye Flashcards
cornea
lets light in and changes directions so light is focused on the retina
iris
coloured part of eye
contains muscles that contract to change the size of pupil
lets more/less light in
ciliary muscle
contracts and relaxes to change shape of lens
retina
layer of receptors at the back of the eye
rods and cones
optic nerve
nerve that connects eye to brain
lens
sits behind pupil and focuses light on retina
how do eyes focus on a NEAR object
ciliary muscles contract
so lens becomes thicker
and more curved
and refracts light rays more strongly
how do eyes focus on a DISTANT object
ciliary muscles relax
so lens is thinner and flatter and onlu refracts light rays partially
myopia
short sightedness
what type of lens is used to aid myopia
concave lens
hyperopia
long sightedness
what type of lens is used to aid hyperopia
convex lens
How can eye defects be treated?
-spectacle lenses
-contact lenses
-laser surgery
-replacement lenses in the
eye
