Human vision

Question 1

Describe Cornea (3 key points)

Answer 1

1. The outer surface of the eye where light enters
2. A layer of transparent tissue made up of living cells 9sensitive to touch & able to heal)

Question 2

Describe Pupil

Answer 2

A dark circular opening that allows light to pass into the eye

Question 3

Describe iris (3 key points)

Answer 3

1. Coloured part of the eye
2. Composed of a circular band of muscles that form the pupil
3. by regulating the size of the pupil, iris controls the amount of light entering the eye

Question 4

Describe retina (2 key points)

Answer 4

1. The inner lining in the back of the eye that acts as a projection for the light rays entering the eye
2. The image on the retina is INVERTED, but the brain interprets the image as being RIGHT SIDE UP

Question 5

what type of lens is a human eye?

Answer 5

Convex lens (real/inverted)

Question 6

Why is the human eye the type of lens it is?

Answer 6

Convex lens - able to adjust its focal length because it is attached to a tiny ring of muscles that can change its shape

Question 7

What do humans focus on when ciliary muscles CONTRACT?

Answer 7

Lens becomes thicker - focus on nearby objects

Question 8

What do humans focus on when ciliary muscles RELAX?

Answer 8

Lens becomes thinner - focus on distant objects

Question 9

What cells is retina composed of?

Answer 9

Photoreceptor cells (sensitive to light)

Question 10

3 classifications of rod cells

Answer 10

1. Detect shape and movement in low light but do not recognize difference colours
2. Only detect shades of grey
3. Located more in the peripheral region of the retina

Question 11

3 classifications of cone cells

Answer 11

1. detect color
2. sensitive to red, green, blue
3. found more in central region of retina

Question 12

At which spot does the optic nerve connect the eye to the brain?

Answer 12

Retina - Blind spot (can’t detect light)

Question 13

4 vision problems

Answer 13

1. Hyperopia (far-sightedness)
2. myopia (near-sightedness)
3. astigmatism
4. presbyopia

Question 14

5 classifications of hyperopia

Answer 14

1. cannot see nearby objects
2. eyeball is too short
3. image forms behind the retina
4. blurry image on the retina
5. converging lens fixes the issue (convex)

Question 15

4 classifications of myopia

Answer 15

1. Cannot see distant objects
2. eyeball is too long
3. image forms in front of retina
4. diverging lens fixes the issue (concave)

Question 16

3 Classifications of Astigmatism

Answer 16

1. Due to irregular cornea shape, eye is unable to form a clear image on the retina
2. Can cause light to refract irregularly
3. can be fixed with a toroidal lens which has 2 focal points

Question 17

3 Classifications of Presbyopia

Answer 17

1. Age related condition
2. As a person ages their lens hardens and becomes less flexible while ciliary muscles become weaker - can’t expand
3. converging lens can correct the problem (convex)

Question 18

What is laser eye surgery?

Answer 18

Procedures that involve correcting vision by reshaping the CORNEA (energy from the laser)

Question 19

why should a person with myopia where concave lenses?

Answer 19

It helps to make faraway objects appear clearer by spreading out the light rays before it enters the eye.

Question 20

What is a blind spot?

Answer 20

an area in where light-sensitive cells (such as in the retina) are absent, resulting in a lack of visual perception for objects within that specific region.