8. Eye & pathology

Question 1

how could acute sinusitis spread into the orbit?

Answer 1

via ethmoid sinus

Question 2

why is diplopia worse on vertical gaze in orbital blowout fracture?

Answer 2

physical entrapment of structures under eyeball

Question 3

management of orbital blowout fracture

Answer 3

CT orbit
refer to opthalmology
prophylactic antibiotics
avoid nose blowing, valsalva manoeuvres and driving until diplopia resolves
follow up 1 week: entrapment enopthalmos and diplopia should improve
or surgical repair after 1-2 weeks if not

Question 4

which cranial nerve and artery/vein is transmitted by
1. optic canal
2. superior orbital fissure
3. inferior orbital fissure

Answer 4

1. optic nerve, ophthalmic artery
2. Va branches, CN 3,4,6, superior ophthalmic vein
3. infraorbital nerve Vb, inferior ophthalmic vein

Question 5

how can venous blood spread from orbit to cavernous sinus?

Answer 5

superior opthalmic vein

Question 6

main arterial supply to orbit and eye

Answer 6

ophthalmic artery, central retinal artery

Question 7

location of central retinal artery

Answer 7

runs inside optic nerve to retina

Question 8

what males up the eyelid?

Answer 8

skin, subcutaneous tissue, muscles, tarsal plate

Question 9

key muscles of eyelid

Answer 9

orbicularis oculi
levator palpeerde superioris

Question 10

where are meibomian glands?

Answer 10

within tarsal plate

Question 11

treatment of
-meibomian cyst
-stye

Answer 11

-nothing, or surgery is persists
-warm compress, maybe oral ABx

Question 12

is a stye painful?

Answer 12

yes

Question 13

blepharitis
-what is it
-cause
-signs
-treatment

Answer 13

-inflamamtion of eyelid margin
-staph, meibomian gland dysfunction
-crusting, dry eyelids, swollen, red
-warm compress and lid hygiene

Question 14

where is periorbital cellulitis? is ocular function affected?

Answer 14

superior to orbital septum
no

Question 15

what to do if unsure periorbital cellulitis vs post septal

Answer 15

refer urgently

Question 16

where is orbital cellulitis?

Answer 16

within orbit or deep to orbital septum

Question 17

signs of orbital cellulitis, why do they occur?

Answer 17

proptosis/exopthalmos
reduce painful eye movements
reduced visual acuity

optic never and extrapcular muscles involved

Question 18

big risk of orbital cellulitis

Answer 18

route for infection to spread intracranially, and cause
-cavernous sinus thrombosis
-meningitis
-permanent blindnes via optic nerve damage

Question 19

management of orbital cellulitis

Answer 19

admit
IV ABx
maybe surgical management if abscess

Question 20

3 layers of tear film, and what produces them

Answer 20

1. oily: meibomian glands
2. water: lacrimal glands
3. mucus: goblet cells in conjunctiva

Question 21

epiphora

Answer 21

obstruction to drainage of tear film

Question 22

conjunctivitis
-cause
-pain?
-symptoms
-infectious?

Answer 22

-viral, infection of conjunctival membrane
-no
-uncomfortable, gritty, red
-yes

Question 23

sub conjunctival haemorrhage
-pain?
-cause

Answer 23

-no
-spontaenous hurts conjunctival blood vessel

Question 24

pigmented part of eye

Answer 24

iris

Question 25

how is central vision achieved?

Answer 25

light focussed onto macula and fovea

Question 26

retinal ganglion cell axons exit the eye as what?

Answer 26

optic nerve via optic disc

Question 27

central retinal artery occlusion

Answer 27

sudden unilateral painless loss of sight, e.g. embolus preventing blood supply to retinal blood vessels

Question 28

nerve supply to retina

Answer 28

choroid blood vessels retinal blood vessels

Question 29

fundoscopy view of central retinal artery occlusion

Answer 29

cherry red spot: macula accentuated as choroid seen more clearly against pale retina pale retina: ischaemia

Question 30

why does blockage of drainage of aqueous humor cause raised IOP?

Answer 30

ciliary body keeps producing, but cant drain away

Question 31

fundoscopy of glaucoma

Answer 31

raise IOP causes optic disc cupping

Question 32

is glaucoma sight threatening?

Answer 32

closed angle is

Question 33

signs of acute closed angle glaucoma

Answer 33

acute painful red eye fixed oval space pupil blurring halos round lights nausea, vominting usually older patient

Question 34

treatment of acute closed angle glaucoma

Answer 34

drugs to rescue IOP then surgery

Question 35

factors needed for sight, and what controls them

Answer 35

1. regulate light entry- pupil 2. reaction: tear film, cornea, lens 3. shape eyeball

Question 36

how does lens become more biconvex?

Answer 36

contraction of ciliary muscle, relaxation of suspensory ligaments

Question 37

phototransduction

Answer 37

conversion of photons to APs via photoreceptors

Question 38

blind spot

Answer 38

optic disc (no photoreceptors)

Question 39

lobe of brain APs sent to for visual interpretation

Answer 39

occipital

Question 40

causes of decreased visual acuity

Answer 40

-opacity of strictures anterior to retina -redcued refractive ability of structures anterior to retina -retina/optoc nerve damage

Question 41

examples of reduced refractive ability of structures anterior to retina

Answer 41

-irregularity of cornea surface: astigmatism -age related lens stiffness: presbyopia -shape of eyeball

Question 42

examples of retina/optic nerve problems

Answer 42

-retinal detachment -age related macular degeneration -optic neuritis

Question 43

red reflex

Answer 43

checks transparency os structures using opthalmoscope

Question 44

how to test if decreased visual acuity is a refractive problem or not? (i.e. transparency OK)

Answer 44

pin hole test- repeat snellen chart by looking through pinhole which allows light to only enter perp to cornea and lens light doesn't need reaction, so if result improves, problem was refractive

Question 45

why do we have binocular vision?

Answer 45

-wider field of vision -depth perception

Question 46

conjugate eye movement

Answer 46

eyes coordinate so images from both hit same spot on retina

Question 47

diplopia

Answer 47

misalignment of two visual axes, focus on different areas of retina so brain cant fuse, see 2 images

Question 48

SR actions

Answer 48

elevate adducts intorts

Question 49

IR actions

Answer 49

depress adducts extorts

Question 50

SO actions

Answer 50

depress intort abducts

Question 51

IO actions

Answer 51

elevate extort abduct

Question 52

strongest elevator when eye is adducted

Answer 52

IO

Question 53

strongest depressor when eye is adducted

Answer 53

SO

Question 54

strongest elevator when eye is abducted

Answer 54

SR

Question 55

strongest depressor when eye is abducted

Answer 55

IR

Question 56

why do patients tilt their head in trochlear nerve palsy?

Answer 56

compensate for extortion

Question 57

strabismus in adults vs children

Answer 57

congenital/infancy in children so less cncerning acquired in adults due to pathology/disease involving neuromuscular junctions/ nerves

Question 58

eye position in CN3 palsy

Answer 58

abducted, depressed ptosis, maybe dilated pupil

Question 59

causes of CN3 palsy

Answer 59

pupil sparing -vasculopathic e.g. DM, HTN pupil involving -compressive, tumour, posterior communicating artery aneurysm, raised ICP)

Question 60

why would a communicating artery aneurysm involve the pupil?

Answer 60

parasympathetics run superficially on CN3 and aneurysm is superficial too

Question 61

eye position on CN4 palsy

Answer 61

extorted, elevated, adducted

Question 62

when is diplopia worst with CN4 palsy? why?

Answer 62

looking down medially e.g. stairs, reading cant get eyeball to look down due to loss of SO

Question 63

causes of CN4 palsy

Answer 63

-vasculitic (DM, HTN) -trauma -congential -tumour

Question 64

eye position in CN6 palsy

Answer 64

adducted

Question 65

causes of CN6 palsy

Answer 65

-DM, HTN -raised ICP

Question 66

worst diplopia with CN6 palsy

Answer 66

horisontal gaze