Human Eye Flashcards
What are the four main parts of the eye?
iris
cornea
lens
retina
The iris is the ______ part of the eye.
What does the iris do?
coloured
It opens and closes to adjust how much light comes through the pupil and reaches the retina
What part of a camera does the iris resemble?
The aperture
What does the cornea do?
Refracts light through the pupil to the lens.
What is the lens and what does it do?
What happens to the image?
A converging lens that refracts the light again after it passes through the cornea to sharpen the image.
The image flips
Where is the retina located?
What does it do?
At the back of the eye.
Converts light energy into electrical signal. This is transmitted to the brain by the optic nerve.
The eye is like a ______. It gathers _____ and focuses an _____ onto the ______.
camera | light | image | retina
Describe the image that is focused onto the retina.
Smaller, real, inverted
What is another name for hyperopia?
What is it and why does it occur?
Far-sightedness
When someone can see far away but has difficulty seeing up close
The image is focused behind the retina because the eye is too short.
How is hyperopia corrected with a lens?
What type of meniscus does it have?
A converging lens is used to refract the light so that the image is brought closer and lands on the retina.
Positive meniscus (thicker in the middle)
What is presbyopia?
A form of far-sightedness caused by aging. The lens loses its elasticity.
What is another name for myopia?
What is it and why does it occur?
Near-sightedness
When someone can close up, but cannot focus on distant objects
A near-sighted eye focuses light in front of the retina`
How is myopia corrected with a lens?
What type of meniscus does it have?
A diverging lens is used to spread out light rays a little so that the eye focuses the image correctly on the retina.
Negative meniscus (thinner in the middle)
