lab exam Flashcards
how can a person with hyperopia see
a person with hyperopia can see objects clearly but nearby objects are blurry.
how is hyperopia caused
it is caused by a shorter eyeball or by a lens that is not curved enough. the lens is unable to make light rays converge onto the retina and the image is focused behind the retina.
how can hyperopia be corrected?
it can be corrected with a biconvex lens which will bring the rays even closer together and focus them onto the retina.
how can a person with myopia see?
a person with myopia can see objects that are close but have difficulty seeing objects at a distance.
how is myopia caused?
this is because of a larger eyeball or a lens that is too thick. the light rays bend too much and are focused in front of the retina rather than directly onto it.
how can myopia be corrected?
it can be fixed by a biconcave lens which will spread out the light rays to allow them to focus on the retina.
what does a converging lens do?
it causes the light rays that travel through it to come together (converge). when light travels through a biconvex lens, the rays always converge to the focal point.
what lens does someone need if they have hyperopia?
biconvex lens
what lens does someone need if they have myopia?
biconcave lens
what does the lens of the eye do?
it causes light rays to converge in order to focus the rays onto the retina
where is the focal point?
at the retina
what does a divergent lens do?
it causes the light rays moving through it to move away from one another.
how do you figure out the focal point of a divergent lens?
you have to extend the refracted rays until they meet.
where is the focal point for people who has myopia?
it is in front of the retina. it doesn’t quite reach
where is the focal point for people who has hyperopia?
it is too far back. after the retina.
