vision

Question 1

diagram of the bony orbit

Answer 1

slide 3; made of 3 bones with several holes at back for nerves and blood supply; fractures when hit by non-sharp object (sclera protects eye as very hard)

Question 2

3 types of tear production

Answer 2

basal, reflex (irritation), crying (emotional)

Question 3

reflex tears: afferent innervation

Answer 3

cornea, V1 (opthalmic division of trigeminal)

Question 4

reflex tears: efferent NS

Answer 4

PSNS

Question 5

reflex tears: neurotransmitter

Answer 5

ACh

Question 6

what produces tears

Answer 6

lacrimal gland

Question 7

movement pathway of tears

Answer 7

lacrimal gland -> drains through two puncta opening on medial lid margin -> flows through superior and inferior canaliculi -> gather in tear sac -> exit through tear duct into nose cavity

Question 8

diagram of lacrimal system

Answer 8

slide 4

Question 9

what does tear film maintain

Answer 9

smooth cornea-air surface

Question 10

3 functions of tear film

Answer 10

oxygen supply to cornea (no blood vessels), removal of debris (including blinking), bactericide

Question 11

3 layers of tear film (external to internal)

Answer 11

superficial oily layer, aqueous tear film, mucinous layer

Question 12

function of superficial oily layer of tear film

Answer 12

reduce tear film evaporation (produced by row of Meibomian glands along lid margins)

Question 13

what is present in aqueous tear film

Answer 13

tear gland

Question 14

function of mucinous layer

Answer 14

on corneal surface to maintain surface wetting

Question 15

what is conjunctiva

Answer 15

thin, transparent tissue covering outer surface of eye

Question 16

location of conjunctiva

Answer 16

begins at outer edge of cornea, covering visible part of eye, and lines inside of eyelids; prevents anything entering behind eye (acts as a sac)

Question 17

what supplies conjunctiva with nutrients, and when are they visible

Answer 17

tiny blood vessels; visible in conjunctivitis

Question 18

diagram of eye

Answer 18

slide 6

Question 19

3 layers of coat of eye (outer to inner)

Answer 19

sclera, choroid, retina

Question 20

3 features of sclera

Answer 20

hard, high water content, opaque (white of eye)

Question 21

features of choroid

Answer 21

pigmented, vascular

Question 22

retina type of tissue

Answer 22

neurosensory

Question 23

function of sclera

Answer 23

protective outer coat

Question 24

what is continuous with sclera anteriorly

Answer 24

cornea

Question 25

what is the cornea

Answer 25

transparent, dome-shaped window covering front of eye

Question 26

main function of cornea

Answer 26

powerful refracting surface, providing 2/3 of focusing power (convex; higher refractive index than air)

Question 27

water content of cornea

Answer 27

low

Question 28

2 other functions of cornea

Answer 28

physical barrier, infection barrier

Question 29

5 layers of cornea (outer to inner)

Answer 29

epithelium, Bowman's membrane, stroma (thick), Descemet's membrane, endothelium

Question 30

how does stroma organisation affect transparency

Answer 30

regular structure increases transparency

Question 31

what provides nutrients and sensation in stroma

Answer 31

corneal nerve endings

Question 32

function of endothelium

Answer 32

pumps fluid out of cornea, preventing corneal oedema

Question 33

suscpetibility and consequence of endothelium dysfunction

Answer 33

only 1 layer and no regeneration power, with cell density decreasing with age, so dysfunction may result in corneal oedema and cloduiness

Question 34

outcome of hydrating cornea

Answer 34

becomes white

Question 35

what is the uvea

Answer 35

vascular coat of eye ball, lying between sclera and retina

Question 36

3 parts of uvea (from front to back); significance of being very close)

Answer 36

iris, ciliary body, choroid; disease of one part also affects other portions (not necessarily to same degree)

Question 37

location and function of choroid (posterior part of uvea)

Answer 37

between retina and sclera; composed of layers of blood vessels that nourish back of eye

Question 38

function of iris

Answer 38

coloured part which controls light levels inside eye (embedded with small muscles that dilate or constrict pupil)

Question 39

name of round opening in iris centre

Answer 39

pupil

Question 40

location of lens

Answer 40

outer acellular capsule

Question 41

structure of lens

Answer 41

regular inner elongated cell collagen fibres, which contribute to transparency

Question 42

name of lens loss of transparency

Answer 42

cataract

Question 43

3 functions of lens

Answer 43

transparency, refractive power (1/3), accomodation (as elastic)

Question 44

what is lens suspended by which causes it to change shape and consequently focus

Answer 44

lens zonules (fibrous ring) which consists of passive connective tissue; when contract, push towards themselves, allowing lens to contract

Question 45

diagram of how lens focuses light

Answer 45

slide 12; image upside down

Question 46

what is the retina and where is it

Answer 46

very thin layer of tissue that lines inner part of eye

Question 47

function of retina

Answer 47

capture light rays, which then are sent as impulses to brain via optic nerve

Question 48

where does optic nerve connect

Answer 48

back of eye near macula

Question 49

what is the visible portion of optic nerve calles

Answer 49

optic disc (most obvious structure; blood vessels become thinner the further forward from optic disc)

Question 50

where is the macula located

Answer 50

centre of retina, temporal to optic nerve

Question 51

what is the macula

Answer 51

small, highly sensitive part of retina (1:1 photoreceptor to neurone ratio)

Question 52

function of macula

Answer 52

detailed central vision (appreciate detail, read etc.)

Question 53

what is the very centre of the macula

Answer 53

fovea

Question 54

section of eye in between upper and lower eyelids

Answer 54

palpebral fissure

Question 55

name of corners of eye

Answer 55

lateral and medial canthus

Question 56

name of white part of eye

Answer 56

sclera

Question 57

name of section inside medial canthus (pink structure)

Answer 57

caruncle

Question 58

name of dark ring acting as border between cornea and sclera

Answer 58

limbus

Question 59

what fills the eye and keeps it in shape

Answer 59

vitreous humour