the eye Flashcards
what is the eye
the eye is a sense organ that contains receptor cells found in a layer called the retina
Retina
light sensitive cells in retina respond to light
cones respond to colour
rods respond to brightness
Lens
focuses light on retina
muscles change shape of lens to cause fine focusing
Cornea
Curved outer surface of cornea causes main focusing of light on retina
Pupil
Allows light to enter the eye
Iris
muscles in the iris control the size of the pupil and how much light enters the eye
Optic nerve
Neurones carry nerve impulses form cone and rods to the brain
Long-sightedness
Light brought into focus behind the retina
Light doesn’t bend enough
Eyeball is too short
Short-sightedness
light brought into focus infront of the retina
Light bends too much
Eyeball is too long
How to correct long sight
Convex lens, bends the light more
How to correct short sight
Concave light, bends the light less
How is colourblindness caused
cones in the eye are not working properly so right colours aren’t processed
Cataract
cloudy patch on the lend, stops light from entering the eye
How to correct cataract
treated by replacing faulty lens with an artificial one
