The Eye

Question 1

what does the cornea do

Answer 1

refracts light into the eye

Question 2

what does the iris do

Answer 2

controls how much light enters the pupil

Question 3

what is the retina and what does it do

Answer 3

• it is the light sensitive part which is covered in receptor cells called rods and cones
• they detect light

Question 4

what is the difference between rods and cones

Answer 4

• rods more sensitive in dim light but cant sense colour

- whereas cones are sensitive to different colours but arent good in dim light

Question 5

what happens to the light information the eye gathers

Answer 5

• it is converted into electrical impulses

- which are carried from the receptors to the brain by optic nerves

Question 6

what is the effect of the lens being elastic in the eye

Answer 6

it can focus light unto the retina by changing the shape of itself

Question 7

what happens to the eye when you look at a distant object

Answer 7

• 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

Question 8

what happens to the eye when you look at a close object

Answer 8

• 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

Question 9

what are long sighted people unable to focus on

Answer 9

near objects

Question 10

what causes people to be long sighted

Answer 10

• the lens is the wrong shape and doesnt bend the light enough
• or the eyeball is too short

Question 11

what types of glasses would you use to correct long sightedness

Answer 11

glasses with a convex lens

Question 12

what are short sighted people unable to focus on

Answer 12

distant objects

Question 13

what causes people to be short sighted

Answer 13

• the lens is the wrong shape and bends the light too much

- or the eyeball is too long

Question 14

what types of glasses would you use to correct short sightedness

Answer 14

glasses with a concave lens

Question 15

what happens to the light coming into the eye with someone who is long sighted

Answer 15

light from near objects is brought into focus behind the retina

Question 16

what happens to the light coming into the eye with someone who is short sighted

Answer 16

light from distant objects is brought into focus in front of the retina

Question 17

what is the most common form of colour blindness and what does it involve

Answer 17

• the most common form is red-green colour blindness

- it is caused when red or green cones in the retina are not working properly

Question 18

is there a cure for colour blindness and why

Answer 18

• no

- because we dont know how to replace cones in the retina

Question 19

what is a cataract and what does it involve

Answer 19

• 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

Question 20

how can cataract be cured

Answer 20

by replacing a faulty lens with an artificial one

Question 21

what is laser eye surgery used for

Answer 21

it is used for repairing the damaged retina to correct vision defects

Question 22

what is done in laser eye surgery

Answer 22

• lasers are used to precisely cut the cornea

- which alters its shape to correct a person’s vision

Question 23

now would laser eye surgery be used to cure short sightedness

Answer 23

• 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