The Eye Flashcards
What is the eye?
A sense organ
Name 2 things the eye is sensitive to
Light intensity and colour of light
What does the cornea do?
Start the focusing on light rays
What does the Iris do?
Coloured part of the eye which controls the size of the pupil
What does the lens do?
Focus light rays onto the back of the eye
Also changes shape so we can focus on distant or near objects
What does the retina do?
Contains receptor cells for light so we can detect light intensity and light colour
What does the optic nerve do?
Sends electrical impulses to the brain
What does the Sclera do?
White part of the eye which protects it
What do the Ciliary muscles do?
works with suspensory ligaments and lens to allow us to focus on distant or near objects
What is the pupil?
Space in the centre of the iris which light passes through
What happens to the iris and pupil in dim light?
Muscles in the iris contract and pupil becomes larger allowing more light to enter
What happens to the iris and pupil in bright light?
Muscles in iris relax and pupil becomes smaller reducing amount of light entering
What is accomodation?
The ability to change the shape of the lens to focus on near or distant objects
What happens to the eye during accommodation for focusing on near objects?
Ciliary muscles contract
Suspensory ligaments loosen
Lens thickens
More light refracted
What happens to the eye during accommodation for focusing on distant objects?
Ciliary muscles relax
Suspensory ligaments tighten
Lens is thinner
Less light refracted
When light rays don’t focus correctly on the retina what 2 things are caused?
Shortsightedness and Longsightedness
State the name for short sightedness
Myopia
State the name for long sightedness
Hyperopia
What does it mean if someone is short sighted?
Cannot focus on distant objects
What causes short sightedness?
Eyeball is too long or lens is too thick
so light is focused in front of the retina or
What does it mean is someone is long sighted?
Cannot focus on nearby objects
What causes long sightedness?
Eyeball is too short so light is refracted behind the retina or lens become too elastic and is too thin
How is Hyperopia treated?
By using glasses with convex lenses
How is Myopia treated?
By using glasses with concave lenses
What does a convex lens do?
Partially focuses light before it enters the eye
What does a concave lens do?
Partially unfocuses light before it enters
Name 3 eye corrections
-Contact lenses
-Laser surgery
-Replacement/artificial lens
What does laser eye surgery do?
Changes the shape of cornea so it refracts light to a greater or lesser extent
