Visual System anatomy (pt1)

Question 1

What is the afferent nerve for the lacrimal system?

Answer 1

Cornea, cranial nerve V1 (ophthalmic trigeminal).

Question 2

What is the efferent nerve for the lacrimal system?

Answer 2

Parasympathetic

Question 3

What’s the neurotransmitter used?

Answer 3

ACh

Question 4

What is the tear film

Answer 4

Most superficial layer of the eye

Question 5

What are the 3 layers it’s made up of and what do they each do?

Answer 5

-Superficial lipid layer
-Aqueous layer
-Mucinous layer

Question 6

What is the conjunctiva?

Answer 6

-Thin, transparent tissue that covers the outer surface of the eye.
-It’s nourished by tiny blood vessels

Question 7

What are the 3 layers of the coat of the eye?

Answer 7

Sclera- Hard, tough and opaque. High water content, responsible for protecting the eye and maintaining its shape. (White of the eye)

Choroid- Pigmented and vascular, provides circulation and shields out unwanted scattered light.

Retina- Neurosensory tissue, converts light into neurological impulses to be transmitted to brain via optic nerve.

Question 8

What is the white of the eye also known as?

Answer 8

Sclera.

Question 9

What is the cornea?

Answer 9

Transparent, dome-shaped window on the front of the eye.

Question 10

Cornea purpose?

Answer 10

Protection and refracting power.

Question 11

What are the 5 layers of the cornea (superficial-deep).

Answer 11

1)Epithilium
2)Bowman’s membrane
3)Stroma
4)Descemet’s membrane
5)Endothelium

Question 12

Which of the layers of the cornea contribute most to transparency?

Answer 12

The stroma and its regularity

Question 13

What happens if you hydrate the cornea.

Answer 13

It becomes white

Question 14

What is the uvea?

Answer 14

The Vascular coat of the eyeball. Lies between the sclera and retina.

Question 15

What are the 3 parts of the uvea

Answer 15

-Iris
-Ciliary body
-Choroid

Question 16

What is the choroid and where is it

Answer 16

Its composed of layers of blood vessels that nourish the back of the eye.
Lies between the retina and sclera.

Question 17

What does the iris do?

Answer 17

Controls Light levels inside the eye.

Question 18

What is the retina?

Answer 18

Very thin layer of tissue lining the inner part of the eye.
Captures light and sends impulses to brain optic nerve for processing.

Question 19

What does the optic nerve do and where is it?

Answer 19

Transmits signals from the retina to the brain,
Connects to the back of the eye near the maculla
Visible portion is called the optic disc

Question 20

What is the blind spot?

Answer 20

Where the optic nerve meets the retina, there are no light sensitive cells.

Question 21

Where is the maculla and what does it do?

Answer 21

Located roughly on the centre of the retina, near optic nerve.

Responsible for detailed central vision.

Question 22

What is the very centre of the maculla called?

Answer 22

The fovea

Question 23

What are the properties of the fovea?

Answer 23

It is the most sensitive part of the retina.
Highest conc of CONES, low conc of RODS.

Question 24

What is central vision?

Answer 24

Detailed day vision, colour vision.

Question 25

How do you assess central vision?

Answer 25

Visual acuity assessment.

Question 26

What does loss of foveal vision lead to?

Answer 26

Poor visual acuity.

Question 27

What is peripheral vision responsible for

Answer 27

-Shape
-Movement
-Navigation
-Night vision

Question 28

How do you assess peripheral vision

Answer 28

Visual field assessment

Question 29

What would extensive loss of visual field cause?

Answer 29

Unable to navigate in environment, may need walking stick even with perfect visual acuity.

Question 30

Describe the retinal structure.

Answer 30

2 layers
Outermost thin layer of retinal pigment epithelium.

Inner thicker layer called neuroretina

Question 31

What is the purpose of the thin and thick layers of the retina

Answer 31

Thin layer- Transports nutrients from the choroid to photoreceptor cells.
Removes metabolic waste.

Thick layer- light detection and signal processing.

Question 32

How is the neuroretina made up.

Answer 32

Made of three layers.
Outer layer-1st order neurons.

middle layer- 2nd order neurons.

inner layer- 3rd order neurons.

Question 33

What are the two types of photoreceptors?

Answer 33

Rods and cones

Question 34

What is the purpose and properties of Rods?

Answer 34

Used for night vision high light sensitivity.
Longer outer segment with photosensitive pigment.

Question 35

What is the distribution of rods in the eye?

Answer 35

Highest concentration of rods in the periphery of the eye.

Question 36

What is the purpose and properties of cones?

Answer 36

Responsible for daylight fine vision and colour vision (photopic vision)
Less sensitive to light but faster response

Question 37

Where are cones mainly concentrated in the eye

Answer 37

The centre of the eye.

Question 38

What is the most common colour vision deficiency and what’s the mechanism?

Answer 38

-DEUTERANOMALY,
-Due to shifting of M cone sensitivity peak towards L cone curve, causing red-green confusion.

Question 39

What is full colour blindness called?

Answer 39

Achromatopsia

Question 40

What does monochromatism refer to?

Answer 40

complete absence of colour vision.

Question 41

What are the different types of monochromatism?

Answer 41

Blue cone monochromatism- Presence of only blue L cones, Normal daylight visual acuity.

Rod monochromatism- Total absence of all cone photoreceptors

Question 42

What is the colour blindness test called?

Answer 42

Isihara test.