The eye

Question 1

Name the different parts in the structure of the eye

Answer 1

1. Cornea
2. Pupil
3. Iris
4. Ciliary muscles
5. Suspensory ligaments
6. Lens
7. Retina
8. Rods &Cones
9. Optic nerve

Question 2

What is the function of the cornea

Answer 2

the cornea is curved and transparent, it refracts light and focuses it onto the lens

Question 3

What does the iris do?

Answer 3

The iris is the coloured part of the eye, it contracts and relaxes to control the volume of light that gets into the eye

Question 4

What is the funciton of the pupil?

Answer 4

The pupil is a gap which allows light to enter the eye

Question 5

What is the funtion of the ciliary muscles?

Answer 5

The ciliary muscles contract and relax which tightens or slackens the suspensory ligaments to change the shape of the lens

Question 6

What is the function of the suspensory ligaments?

Answer 6

The suspensory ligaments connecte the lens to the ciliary muscles. They slacken or tighten when the ciliary muscles contract or relax to change the shape of the lens

Question 7

What is the funciton of the lens?

Answer 7

The lens refracts light to focus it onto the retina

It can change shape, allowing us to focus on near or far objects

Question 8

What is the funtion of he retinaa?

Answer 8

The retina detects light

Question 9

Name the two light receptors on the retina

Answer 9

1. Cones
2. Rods

Question 10

What is the funtion of the cones on the retina

Answer 10

they detect the colour of light

Question 11

What is the function of the optic nerve

Answer 11

The optic nerve is a sensory neurone which sends electrical impulses form the eye to the brain

Question 12

What is the function of the sclera?

Answer 12

The sclera is the tough white outer layer on the eye which protects the eye form damage

Maintains the shape of the eye

Question 13

How does the eye accomodate to focus on near objects?

Accomoation in the eye

Answer 13

1. The ciliary muscles contract
2. This causes the suspensory ligaments to slacken
3. This causes the lens to become round and fat, so it can refract light more strongly

Question 14

How does the eye accomodate to focus on far away objects?

Accomodation in the eye

Answer 14

1. The ciliary muscles relax
2. This cause the suspensory ligaments to become stretched and tighter
3. This causes the lens to become long and thin so it refracts light less strongly

Question 15

How do the muscles in the eye adapt to bright light

Answer 15

1. The light receptors in retina detect dim light levels
2. Electrical impulses transmitted across neurone
3. Causes the ciliary muscle contracts and gets smaller
4. The radial muscles relax so pupil then constricts
   This limits the volume of light that can enter the eye to protect the retina as it is very sensetive to light

it is an unconscious process so the brain is NOT invloved

Question 16

How do the muscles in the eye adapt to dim light?

Answer 16

1. Light detectors in retina detect dim light levels
2. Electrical impulses travel along neurone
3. Causes the ciliary muscles relax and become larger
4. The radial muscles contract so the pupil is dilated
   This allows a larger volume of light to enter the eye

It’s an unconscious process. So the brain is not involved

Question 17

What is myopia?

Answer 17

Myopia (shortsightedness)
Is when the lens refracts light too much so the image is brought into focus infront of the retina

Question 18

What causes myopia to occur

Answer 18

1) The lens is too round and thick. so it refracts light too much

or

2) The lens in too far away from the retina

Question 19

What type of corrective lens in used to correct myopia

Answer 19

Concave lens

Question 20

How does the concave lens correct myopia

Answer 20

It refracts light less strongly so the image focuses on the retina

Question 21

What is hyperopia?

Answer 21

hyperopia (long-sightedness) is when the lens does not refract the light enough so the immage is brought into focus behind the retina

Question 22

What are the two causes of hyperopia?

Answer 22

1) The lens is too long and thin, so it does not refract light enough

or

2) The eyeballis too short so the lens is too close to the retina

Question 23

Which type of corrective lens is used to correct hyperopia?

Answer 23

Convex lens

Question 24

What does a convex lens do?

Answer 24

It refracts light more strongly so that the image is focused onto the retina

Question 25

**Name** the **new technologies** which have been used to **correct eye defects**

Answer 25

1. **Hard** or **soft contact lenses** 2. **Laser eye surgery** to **change** the **shape** of the **cornea** 3. **Replacement lens** in the **eye**

Question 26

How is **laser eye surger** used to **correct myopia**?

Answer 26

A **laser** is used to **vaporise tissue** This **changes** the **shape** of the **cornea** **Slimming down** the cornea causes light to be **refracted less strongly** so the **image** is **focused** onto the **retina**

Question 27

How is **laser eye surgery** used to **correct hyperopia**?

Answer 27

The **laser** is used to **vaporise** the tissue This **changes the shape** of the **cornea** The **shape** of the **cornea** is **changed** to become **thicker** so that the **light** is **refracted** more **strongly** and the **image** is **focused** onto the **retina**

Question 28

What are the **risks** and **disadvantages** of **laser eye surgery**?

Answer 28

It can cause **infection** The **eye** may **react** in a way that **makes vision worse** It's **expensive**

Question 29

What do **contact lenses** do?

Answer 29

**Contact lenses** sit on the **surface** of the eye to help it to **refract light correctly**

Question 30

What are **advantages** and **disadvantages** of **contact lenses**

Answer 30

**Adv:** They are **lightweight** **soft lenses** are **comfortable** **Convinient** for **sport** **Disadv:** **Soft lenses** carry a **higher risk** of **infection** **Makes eyes dry** Can **only be worn** for a **certain amount** of **hours**

Question 31

What is **lens relacement surgery**?

Answer 31

When a **faulty lens** is **surgically removed** and **replaced** with an **artificial plastic lens**

Question 32

What are **disadvantages** of **lens replacement**

Answer 32

It is **extremely risky** as it could **damage** the **retina**. This means that the **patient** would **lose** their **eyesight** altogether.

Question 33

Why is the **reflex** of **adapting** our **eyes** to **dim/bright** light **important**

Answer 33

The **retina** and the **light detectors** (**cones and rods**) on the retina are **extremely sensetive** to **bright light** and **can be damaged** if they are **exposed** to **light** which is **too bright**. This reflex is therefore **important** as it **controls** the **volume of light** that **enters** the **eye**.

Question 34

**State** the **name** of the **process** which **changes** the **shape** of the **lens**

Answer 34

**Accomodation**