the eye Flashcards
what is the far point?
it is the furthest distance the eye can focus on
what is the far point for normal sighted people?
infinity
what is the near point?
the closest distance the eye can focus on (25cm)
what happens as the eye focuses on closer objects?
- the power increases
- lens changes shape and focal length decreases
- distance between lens and image stays same
how does a film produce an image?
the image is real, smaller because the object is a lot further away than focal length of lens and it is inverted
how can a film or ccd relate to an eye?
they both detect light focused on them and record it
cornea
it is a transparent window with a convex shape and a high refractive index, it does most of the focusing
iris
is the coloured part. it is made of muscles which control the size of the pupil which controls the light intensity
lens
changes shape and focuses light from the object at varying distances
how is the lens connected to the ciliary muscles?
by suspensory ligaments
what happens when the ciliary muscles contract?
tension is released and the lens becomes a fat and spherical shape
what happens when the ciliary muscles relax?
the suspensory ligaments pull lens into a thinner and flatter shape
what is the image formed on the retina covered in?
light sensitive cells, which detect light and send signals to the brain to be interpreted
