The Eye Flashcards
what does the cornea do
refracts light into the eye
what does the iris do
controls how much light enters the pupil
what is the retina and what does it do
- it is the light sensitive part which is covered in receptor cells called rods and cones
- they detect light
what is the difference between rods and cones
- rods more sensitive in dim light but cant sense colour
- whereas cones are sensitive to different colours but arent good in dim light
what happens to the light information the eye gathers
- it is converted into electrical impulses
- which are carried from the receptors to the brain by optic nerves
what is the effect of the lens being elastic in the eye
it can focus light unto the retina by changing the shape of itself
what happens to the eye when you look at a distant object
- the ciliary muscle relaxes
- which allows the suspensory ligaments to pull tight
- this pulls the lens into a less rounded shape
- so the light is refracted less to make an image at the retina
what happens to the eye when you look at a close object
- the ciliary muscle contracts
- which slackens the suspensory ligaments
- the lens becomes a more rounded shape
- so might is refracted more to make an image at the retina
what are long sighted people unable to focus on
near objects
what causes people to be long sighted
- the lens is the wrong shape and doesnt bend the light enough
- or the eyeball is too short
what types of glasses would you use to correct long sightedness
glasses with a convex lens
what are short sighted people unable to focus on
distant objects
what causes people to be short sighted
- the lens is the wrong shape and bends the light too much
- or the eyeball is too long
what types of glasses would you use to correct short sightedness
glasses with a concave lens
what happens to the light coming into the eye with someone who is long sighted
light from near objects is brought into focus behind the retina
what happens to the light coming into the eye with someone who is short sighted
light from distant objects is brought into focus in front of the retina
what is the most common form of colour blindness and what does it involve
- the most common form is red-green colour blindness
- it is caused when red or green cones in the retina are not working properly
is there a cure for colour blindness and why
- no
- because we dont know how to replace cones in the retina
what is a cataract and what does it involve
- it is a cloudy patch on the lens which stops light from being able to enter the eye properly
- people with it are likely to have blurred vision or have colours be less vivid
- or have difficulties seeing bright light
how can cataract be cured
by replacing a faulty lens with an artificial one
what is laser eye surgery used for
it is used for repairing the damaged retina to correct vision defects
what is done in laser eye surgery
- lasers are used to precisely cut the cornea
- which alters its shape to correct a person’s vision
now would laser eye surgery be used to cure short sightedness
- short sightedness is when the lens refract light too intensely or the eyeball is too short causing the image to be focused in front of the retina
- to fix this with laser eye surgery, the lasers would be used to precisely cut the cornea
- in order to decrease the intensity of the corneas curve
- so that the light is refracted less intensely and the image is formed on the retina
