structure of the eye and accommodation.

Question 1

what does the retina of the eye do?

Answer 1

contains receptor cells, sensitive to brightness and colour of light.

Question 2

what does the optic nerve do ?

Answer 2

carries impulses from retina to brain.

Question 3

what does the sclera do ?

Answer 3

forms a tough outer layer with a transparent region at the front called the cornea.

Question 4

what does the iris do ?

Answer 4

controls the size of the pupil and the amount of light reaching the retina.

Question 5

what does the ciliary muscles and suspensory ligaments do ?

Answer 5

change the shape of the lens to focus light onto the retina.

Question 6

what does accommodation mean?

Answer 6

process of changing the shape of the lens to focus on near or distant objects.

Question 7

to focus on something near what has to happen in the eye?

Answer 7

ciliary muscle contracts.
suspensory ligament loosen.
lens become thicker and refracts rays strongly.

Question 8

to focus on something far away what has to happen in the eye?

Answer 8

ciliary muscles relax.
suspensory ligaments pulled tight.
lens is pulled thin and only slightly refracts light rays.

Question 9

what are the 2 common eye defects, what is it caused by and how can you fix it?

Answer 9

myopia- short sightedness- light rays don’t focus on retina.
hyperopia- long sightedness.
treated with spectacle lenses refract light rays so they focus on the retina.
new technology includes: contact lenses, laser surgery to change the shape of the cornea, replacement eye lenses.