Vision 2

Question 1

What is the point at which central retinal artery and vein pierce the eyeball called?

Answer 1

Lamina cribrosa (sieve like thinned area)

Question 2

What branch does the internal carotid artery give to the eye?

Answer 2

Ophthalmic artery - which then branches into central retinal artery

Question 3

What part of the eye is supplied by the central retinal artery?

Answer 3

inner 2/3 retina

Question 4

What structures pass through lamina cribrosa?

Answer 4

optic nerve

central retinal artery and vein

Question 5

What is the most common cause of a blockage in the central retinal artery?

Answer 5

clot travelling from internal carotid

Question 6

Are arteries or veins thinner in the eye?

Answer 6

arteries

Question 7

What are the four divisions of the central retina artery when it enters the eye?

Answer 7

• superotemporal
• inferotemporal
• inferonasal
• superonasal

Question 8

What blood vessels supply the rest of the retina (not supplied by central retinal artery)?

Answer 8

choroid

Question 9

What can occur to the fovea in diabetes

Answer 9

foveal avascular zone increases as you get capillary dropout

Question 10

How does raised ICP affect the eye?

Answer 10

pressure is transmitted along the subarachnoid space which is found around the optic nerve
resulting in compression of the central retinal vein causing papilloedema

Question 11

What three things should be described when checking the optic disc?

Answer 11

Colour
Contour
Cupping

Question 12

If the contour of the optic disc is indistinct what does this mean?

Answer 12

disc is swollen which often occurs in raised ICP

Question 13

What colour should the optic disc rim be?

Answer 13

Orange, if there is a pathology will change to be pale

Question 14

What are the branches of the ophthalmic artery?

Answer 14

Central retinal 
ciliary arteries 
- long posterior ciliary 
- short posterior ciliary 
- anterior ciliary

Question 15

What does the ciliary arteries supply?

Answer 15

Uvea (choroid, ciliary body + iris)

Question 16

At what point does the retina stop anteriorly?

Answer 16

Ora serrata

Question 17

What is the name of the membrane found between the retina and choroid?

Answer 17

Bruck’s membrane (part of Retina) just outisde the RPE cells

Question 18

How do the RPE cells connect to the photoreceptor cells?

Answer 18

Axons of the RPE

Question 19

What two factors prevent opening of the space between photoreceptors and RPE cells (sub retinal space)

Answer 19

• pumping out of water by RPE cells creates negative pressure pulling them together
• glycosaminoglycans (act as glue)

Question 20

What allows the RPE to create a blood brain barrier?

Answer 20

have tight junctions

Question 21

What substances does the RPE cells take up from the general circulation?

Answer 21

• glucose
• retinal
• specialised phospholipids used in creation of photoreceptors

Question 22

Why is RPE so oxidative?

Answer 22

RPE take up parts of old photoreceptors and breaks them down using lysosomes & in the process releasing free radicals

Question 23

What is the function of the choroid outside of O2 and nutrient deliver?

Answer 23

• take heat away

- melanosomes (pigment granules) absorb light and heat up as result

Question 24

Describe the initiation of the visual cycle in rods

Answer 24

• photon of light absorbed by 11-cis retinal (in photoreceptors)
• this causes change in conformation of 11-cis retinal (called bleaching)
• creates all-trans retinal & free opsin
• RPE (not photoreceptors) reform 11-cis retinal

Question 25

How does creation of opsin result in visual signal being sent along visual pathway?

Answer 25

- opsin closes Na channels on outer segment of photoreceptors - Na usually allowed to flow freely into photoreceptors - blocked so Na in cells fall and transmembrane potential fall - hyper-polarisation is transmitted along visual pathway

Question 26

What is the function of RPE?

Answer 26

- absorb light - phagocytose photoreceptor segments - secretes VEGF (vascular endothelial growth factor)

Question 27

What is the function of VEGF?

Answer 27

keep capillaries of choroid fenestrated (and leaky)

Question 28

What cells must the AP pass through to get from photoreceptor to optic nerve?

Answer 28

``` photoreceptor (rod & cone) (horizontal cells) 1) bipolar cells 2) Amacrine cells 4) ganglion cells (axons of these stream toward optic nerve) ```

Question 29

How should dark and light areas of an OCT be described?

Answer 29

Hypo-reflexive (dark) | Hyper-reflexive (light)

Question 30

What is the pathway of the optic nerve from the eye to optic chiasm?

Answer 30

1) when first leaves eyeball orbital portion passes posteriorly through optic canal (hole in sphenoid bone) 2) Intracranial portion moves upward and backward toward floor of third ventricle 3) where meets the optic nerve of the opposite side at optic chiasm

Question 31

What aspects of your vision would a pituitary tumour affect?

Answer 31

temporal vision in both eyes

Question 32

What is the pathway of the optic nerve from the chiasm to primary visual cortex?

Answer 32

- travel posterolaterally - fibres synapse at LGB (lateral geniculate body) - optic radiation part of optic nerve passes from LGB to primary visual cortex

Question 33

What would be the visual impairment if there was a lesion in the optic chiasm?

Answer 33

bitemporal hemianopia | lose peripheral vision in both eyes, still have central vision

Question 34

What would be the visual impairment if there was a lesion in the right optic nerve?

Answer 34

total right eye visual loss

Question 35

What would be the visual impairment if there was a lesion in the left optic nerve after chiasm?

Answer 35

right homonymous hemianopia | lose right side of vision in both eyes

Question 36

What would be the visual impairment if there was a lesion in the right side optic radiation?

Answer 36

left homonymous hemianopia with macular sparing | lose vision in left side of both eyes

Question 37

Where do optic nerve fibres first synapse?

Answer 37

90% synapse at LGB Lateral geniculate body | 10% synapse at pretectal nucleus

Question 38

Why do both pupils constrict in the pupillary light reflex?

Answer 38

after those 10% of fibres divert before the LGB to synapse at the pretectal nucleus they travel to Edinger Westphal nucleus (EWN) on both sides which then travels via CN3 to ciliary sphincter