Anatomy of the Visual System

Question 1

How many types of tears are there? What are they called?

Answer 1

3 types
Basal
Emotional
Reflex

Question 2

What are the afferent components of the lacrimal system?

Answer 2

Cornea, cranial nerve 1 supplies it

Question 3

What are the efferent components of the lacrimal system?

Answer 3

Parasympathetic

Question 4

What neurotransmitter is involved with the lacrimal system?

Answer 4

Acetylcholine

Question 5

What produces tears?

Answer 5

Lacrimal gland

Question 6

What do tears drain through?

Answer 6

The 2 puncta, these are the opening on the medial lid margin, they then go through the tear duct and

Question 7

Where do tears gather?

Answer 7

In the tear sac

Question 8

What is the role of the tear film?

Answer 8

Maintain a smooth cornea to air surface
Provide oxygen supply to the cornea
Allow removal of debris alongside blinking

Question 9

What is the blood supply to the cornea?

Answer 9

There is no blood supply to the cornea

Question 10

How may layers are there to the tear film? What are they called?

Answer 10

3 layers (from superficial to deep they are):
Lipid layer (reduces tear evaporation)
Water layer
Mucin layer (maintains surface wetting)

Question 11

What is the conjunctiva?

Answer 11

A thin, transparent tissue that covers the inner surface of the visible eye, starts at the cornea and runs on the inside of the eyelid

Question 12

What is the blood supply to the conjunctiva?

Answer 12

Supplied by tiny blood vessels that we can’t see

Question 13

How many layers are there in the coat of the eye? What are they called?

Answer 13

3 layers (fro outer to innermost they are):
Sclera
Choroid
Retina

Question 14

What is the sclera?

Answer 14

The outermost layer of the coat of the eye, it is the white of the eye and has a high water content

Question 15

Describe the choroid

Answer 15

Pigmented and vascular

Question 16

What type of tissue does the retina contain?

Answer 16

Neurosensory tissue

Question 17

How many layers does the cornea have? What are they called?

Answer 17

5 layers:
Epithelium
Bowman's membrane
Stroma
Descement's membrane
Endothelium

Question 18

What is the cornea?

Answer 18

The transparent dome shaped window covering the front of the eye

Question 19

Describe the water content of the cornea

Answer 19

Low

Question 20

What is the role of the cornea?

Answer 20

It is a powerful refracting surface (2/3 of the eyes refracting power)

Question 21

What is the significance of the endothelium of the cornea?

Answer 21

It pumps fluid out of the cornea and prevents corneal oedema

Question 22

How is corneal oedema prevented?

Answer 22

The endothelium layer of the cornea pumps our fluid

Question 23

What is the uvea?

Answer 23

It is the vascular coat of the eyeball

Question 24

What does the uvea lie between?

Answer 24

The sclera and the choroid

Question 25

How many layers are there in the uvea? What are they called?

Answer 25

3 layers Iris Ciliary body Choroid

Question 26

Describe the role of the iris

Answer 26

It controls how much light is let into the eye, and has an opening in the middle which is the pupil. Muscles allow the pupil to constrict and relax

Question 27

What is the choroid composed of?

Answer 27

Tiny blood vessels that nourish the eye

Question 28

What is the role of the lens?

Answer 28

To allow transparency | Has refractive power also (1/3 of the eye)

Question 29

What is the outside of the lens known as?

Answer 29

Acellular capsule

Question 30

What is it called when lens transparency is lost with age?

Answer 30

Cataract

Question 31

Describe the retina and where its found

Answer 31

It is a very thin layer of tissue that lines the back of the eye

Question 32

What is the role of the retina?

Answer 32

To capture light rays that enter the eye

Question 33

What happens to light rays that are captured by the retina?

Answer 33

They are sent to the brain for processing via the optic nerve

Question 34

What is the optic disc?

Answer 34

The visible part of the optic nerve that connects to the retina

Question 35

Where does the optic nerve connect to the eye?

Answer 35

At the back near the macula

Question 36

What is formed where the optic nerve meets the retina?

Answer 36

A blind spot, there are no sensitive light cells here

Question 37

How many layers are there to the retina? What are they called and what are their roles?

Answer 37

3 layers Outer layer: photoreceptors, 1st order neurons, detect light Middle layer: Bipolar cells, 2nd order neurons, local signal processing to improve contrast sensitivity Inner layer: retinal ganglion cells, 3rd order neurons, transmits signals from eye to brain

Question 38

What type of cell is found in the outer layer of the retina?

Answer 38

Photoreceptors

Question 39

What type of cell is found in the middle layer of the retina?

Answer 39

Bipolar cells

Question 40

What type of cell is found in the inner layer of the retina?

Answer 40

Retinal ganglion cells

Question 41

What is the macula?

Answer 41

A small highly sensitive part of the retina that is responsible for detailed central vision and perception of detail to allow eg reading

Question 42

What is the fovea?

Answer 42

The centre of the macula, the most sensitive part of the retina

Question 43

What type of cells are found in the fovea?

Answer 43

Highest conc of cones (allows perception of detail) and lowest conc of rods

Question 44

What does central vision include?

Answer 44

Detailed vision during the day | Colour vision

Question 45

What is central vision used for?

Answer 45

Reading and facial recognition

Question 46

How is central vision assessed?

Answer 46

Visual acuity assessment

Question 47

What does peripheral vision include?

Answer 47

Shape, movement, night vision, navigation vision

Question 48

How is peripheral vision assessed?

Answer 48

Visual field assessment

Question 49

What happens if there is a loss of visual field?

Answer 49

This is an impairment in peripheral vision and so people cannot navigate

Question 50

What are photoreceptors for?

Answer 50

Visual processing

Question 51

What are the 2 types of photoreceptors?

Answer 51

Rods and cones

Question 52

Describe rods

Answer 52

They have a long outer segment which is photo-sensitive, they have a slow response to light but are 100x more sensitive to light than cones, they are responsible for night vision

Question 53

What is the scientific name for night vision?

Answer 53

Scotopic vision

Question 54

Out of rods and cones which is more sensitive to light?

Answer 54

Rods

Question 55

Describe cones

Answer 55

Less sensitive to light but fast response to light, responsible for day vision and colour vision

Question 56

What is the scientific name for day vision?

Answer 56

Photopic vision

Question 57

How does the eye see colour?

Answer 57

Through different photoreceptors S cones= blue M cones= green L cones= red

Question 58

What are the names of the different photoreceptors?

Answer 58

S cones M cones L cones

Question 59

What colour do s cones capture?

Answer 59

Blue

Question 60

What colour do m cones capture?

Answer 60

Green

Question 61

What colour do l cones capture?

Answer 61

Red

Question 62

What colours are rods sensitive to?

Answer 62

No colours

Question 63

What is deuteranomaly?

Answer 63

Partial colour blindness (the most common form) where they dont perceive red

Question 64

What is achromatopsia?

Answer 64

Full colour blindness

Question 65

What test is used to diagnose colour blindness?

Answer 65

Ishihara test