intro to eyeballs Flashcards
What is the macula
The pigmented part of the retina located in the very center.
what is the fovea
The fovea is the area of best visual acuity. It contains a large amount of cones—nerve cells that are photoreceptors with high acuity.
What is the order of the parts of the eye that light shines through when we see things
light reflects off of objects and goes through:
1. cornea
2. iris
3. pupil
4. lens
5. retina
6. optic nerve carries those light signals to brain.
what does hyperopia cause
farsightedness (nearby objects look blurry)
what part of the eye is where light actually enters the eye
the pupil
what is the job of the lense of the eye
to focus the light entering the eye by bending/flattening/changing shape to focus the light rays
What are the parts of the eye that are in charge of changing the shape of the lense
ciliary body/ciliary muscles
suspensory ligaments
How would the lense shape change in order to see an object that is near to you.
- ciliary muscles contract
- suspensory ligaments slacken
- lens becomes thicker
- light focuses on retina
How would the lense shape change in order to see an object that is far away from you.
- ciliary muscles relax
- suspensory ligaments become taut
- lens becomes thinner
- light focuses on retina
what happens to the focal length of the lens when looking at a close by object
focal length of the lens decreases
what happens to the focal length of the lens when looking at a far away object
focal length of the lens increases
What causes hyperopia
too little curvature of the cornea due to the eyeball being too short for the refractive power of the cornea and lens
What is the focal point
where light focuses precisely on the retina.
For good vision, the focal point must be on the retina
What is refraction
the process of bending light to produce a focused image on the retina.
why do most vision problems occur
because of an error in how our eyes REFRACT light
when do refraction errors occur
when the shape of your eye keeps light from focusing correctly on your retina
What are the types of errors of refraction
myopia
hyperopia
astigmatism
presbyopia
keratoconus
what causes myopia
too much curvature of the cornea due to the eyeball being too long for the refractive power of the cornea and lens.
What is the result of myopia
nearsightedness (trouble seeing distant objects)
where is the focal point in someone with myopia
in front of the retina
how is myopia corrected
with a concave lens
“Wide view lens, diverges light rays, makes objects look smaller than they are” idk what any of this means
where is the focal point in people who have hyperopia
light is focused behind the retina
how do you correct hyperopia
with a convex
“The rays meet at a single point on other side of lens
Magnify objects to make them look larger”
“Such lenses are used to focus a beam of light on making the object look clearer and larger.”
again, not sure what this means but im sure its important
describe the effect of a concave lens
- Spreads out light rays
diverging - Focal point in front of lens
- Parallel rays of light pass through the lens are spread out
- Image formed is smaller but clear
- Gives wider viewing angle