The Eye

Question 1

What are the 8 parts to the eye?

Answer 1

Iris, lens, pupil, cornea, ciliary muscles, retina, optic nerve, suspensory ligaments

Question 2

How are we able to see things?

Answer 2

Rays of light are refracted (bent) first by the cornea and then by the lens. They then focus on the retina.

Question 3

What is the range of vision for an eye?

Answer 3

25cm - infinity

Question 4

How are we able to see distant objects?

Answer 4

For distant objects the ciliary muscles relax and the suspensory ligaments pull tight making the lens pull thin – the light doesn’t bend as much.

Question 5

How are we able to see close object?

Answer 5

For close objects the ciliary muscles contract allowing the lens to go fat, thus bending the light more.

Question 6

What lens tends to be used for short distances (short sighted people?

Answer 6

Diverging (concave) lens

Question 7

What lens tends to be used for long distances (long sighted people?

Answer 7

Converging (convex) lens

Question 8

What is the equation for power in dioptres?

Answer 8

Power in dioptres = 1 / focal length in m

Question 9

What are the advantages of laser eye surgery?

Answer 9

• you don’t have to wear contact lenses or glasses

- it can make precise incisions in tissue without damaging the surrounding areas

Question 10

What are the disadvantages of laser eye surgery?

Answer 10

• the point at which light rays meet the inside of the eye has changed
• it is expensive
• there are many risks associated with it