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CMS - term 1 > Opthalmology > Flashcards

Opthalmology Flashcards

1
Q

farm animal - primary eye diseases

A

infectious bovine keratoconjunctivitis - fly eye (pink eye/new forest disease)
iritis - silage eye
squamous cell carcinoma - cancer eye
foreign body

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2
Q

farm animal - secondary eye disease

A

eye lesion as a result of other disease

malignant catarrhal fever
IBR
Listeria

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2
Q

farm animal - systemic state indication in eyes

A

BVD - cataracts - youngstock, no associated blepharospasm or excessive lacrimation
septicemia - hypopyon - pus in anterior chamber (associated with meningitis)
endotoxemia - congested conjunctiva (Red puffy looking)
dehydration - sunken eyes

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3
Q

Fly eye - causes

A

spread by flies - more common in summer
moraxella bovis (gram -ve)

more common in youngstock

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3
Q

fly eye - signs

A

lacrymation - serous initially, can become mucopurulent
blepharospasm
varying degrees of keratitis - fluoroscein
ulceration and corneal pannus - vascularisation and reduction in vision
photophobia - can make handling difficult
pain

unilateral or bilateral

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4
Q

fly eye - treatment

A

topical antibiotic - cloxacillin - always need this
systemic/subconjunctival antibiotic injection - amoxycillin/oxytetracycline, behind eye
suture - local nerve block then either eyelids together or 3rd eyelid to eyelid - protect eye
eye patch
NSAIDs - very painful

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5
Q

fly eye - risk factors

A

flies
woodland
dust/chaff
UV light
viral pneumonia - reduced immune system and ocular discharge

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6
Q

fly eye - prevention

A

fly control - pour on, tags, parasitic wasps, slurry management, ventilation
graze away from woodland
good ventilation
vaccination available

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7
Q

Silage eye - causes

A

big bale silage feeding - listeria monocytogenes in badly bailed silage
could be secondary to trauma
more common in winter

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8
Q

silage eye - signs

A

miosis - contricted pupil
blepharospasm
corneal opacity - diffuse or multifocal
glaucoma
fibrin accumulation in anterior chamber
corneal vascularisation in advanced cases

differing from fly eye -
signs on inside of cornea
no corneal ulceration - -ve fluorescein

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9
Q

silage eye - treatment

A

acute - oxytetracycline and dexamethosone into conjunctiva, topical atropine if miosis

chronic - usually not effective, can resolve without treatment but slowly and can have permanent blindness

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10
Q

silage eye - prevention

A

remove ring feeder - roll out silage
attention to bailing and wrapping of silage - prevent listeria growth
don’t leave bales open too long

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11
Q

cancer eye - risk factors

A

squamous cell carcinoma
older beef cattle - <5 yo
breed disposition - hereford and simmental
UV exposure - higher incidence in tropics

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12
Q

cancer eye - signs

A

unilateral
usually 3rd eyelid but anywhere in conjunctiva
swelling as tumour grows
local invasion of tissues
bad smell

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13
Q

cancer eye - management

A

surgical excision of 3rd eyelid
enucleation

usually just to hold them over to abattoir - reoccurrence high

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14
Q

encucleation

A

standing surgery - xylazine and retrobulbar block
elliptical incision around orbit
blunt dissection of conjunctival tissue to access retrobulbar space
ligate optic vessels - orbital packing to control haemorrhage
remove eye - cut optic nerves and vessles
suture eyelids together - simple interrupted - leave space to remove packing
packing removed 3-5 days later

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15
Q

foreign bodies - farm animal eye

A

straw, grass seed etc
can progress to keratitis
local blocks - easier examination
remove irritant and assess damage
antibiotics and pain relief

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16
Q

malignant catarrhal fever - cause

A

ovine herpesvirus2 - transmitted from contact with sheep or goats
cattle don’t transmit

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17
Q

malignant catarrhal fever - signs

A

runny eyes and nose
sudden depression, anorexia, and pyrexia
bilateral eye congestion, keratitis, and corneal opacity from outside in
mucopurulent discharge
leads to blindness
nasal discharge and crusting/sloughing off of muzzle
stomatitis
generalised peripheral lymphadenopathy
enteritis –> diarrhoea

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18
Q

malignant catharral fever - prevention and treatment

A

diagnosis - antibodies in serum, clinical digns, post mortem

no treatment - euthanasia

prevention - avoid contact with sheep/goats

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19
Q

IBR - eyes

A

bovine herpesvirus1

latent in trigeminal ganglion
vaccine availablae

runny eyes but mot as bad as MCF
pyrexia
conjunctivitis and discharge
corneal oedema
nasal lesions and discharge
tracheitis (differentiates from MCF)
milk yield drop

20
Q

Sytemic listeriosis - eyes

A

listeria monocytogenes
infection via trigeminal or facial nerve - neuro damage causing secondary eye damage

encephalitis - circling in one direction
unilateral facial paralysis
depression
pyrexia
abortion
blindness - negative menace test
dry eye –> secondary keratitis (facial paralysis so can’t blink or move eye to move tears around)

21
Q

large animal eye blocks - palpebral

A

lidocaine
subcutanrous at crest of rostral zygomatic arch
facial nerve (palpebral branch)

motor only, not sensation

innervation to eyelids

22
Q

large animal nerve blocks - supraorbital

A

lidocaine
inject lidocaine over the depression of the supraorbital foramen

trigeminal nerve (supraorbital branch)

sensory

analgesia to upper lids

23
Q

large animal nerve blocks - retrobulbar

A

lidocaine
curved needle between globe and bony orbit, inject at back of eye until the eye feels turgid

sensory and motor to whole eye - only for eye removals, risk of trauma to optic nerve or artery

24
Q

Schirmer Tear Test

A

normal range - 15 - 25mm/min
dry eye (keratoconjunctivitis sicca) - under 15mm/min

measures aqueous component of tears
test before putting anything else in

25
Q

cranial nerves affecting eyes and adnexa

A

2 - optic - sensory - eye reflexes
3 - oculomotor - motor - most eye muscles
4 - trochlear - motor - other eye muscles
5 - trigeminal - both (Sensory to eye) - corneal pain
6 - abducens - motor - other eye muscles
7 - facial - motor - facial expression muscles (inc eye)
8 - vesibulocohlear - both - balance (so can look like a vision problem)

26
Q

eye neuro exam

A

menace response - learned, absent before 8 weeks in puppies and 2 weeks in foals

dazzle reflex - if dazzle but no menace then good chance can get vision back, nervous communication to brain still in tact (eg in cataracts if remove the cataract)

palpebral reflex - can have inability to blink and negative menace because of this rather than blindness

pupillary light reflex - direct and consensual

27
Q

tonometry

A

normal pressures -
dog/cat - 15-25mmHg
horse - 16-30mmHg

should be max 5mmHg difference between the two eyes, if more need to work out which one is high/low

glaucoma - high pressure
uveitis - low pressure

false elevation through pressure on eye or jugular vein or position of head too low in relation to heart

measure before dilating pupils

28
Q

ophthalmic dyes

A

fluorescein
jones test - fluorescein down nasolacrimal duct (open mouth in brachys)
rose bengal - tear film abnormalities, UV damaged cells, early squamous cell carcinoma

29
Q

cytology eye

A

any ulcer with dimples
any fluorescein positive lesion - especially with opacity
any ulcer not holding normal shape

take 2 slides
look for rods, cocci, hyphae, neutrophils, eosinophils
culture and sensitivity

30
Q

ophthalmic antibiotics

A

penicillins
aminoglycosides
tetracyclines
chloramphenicol
fusidic acid (isothal)
fluroquinolines

modes of action - protein synthesis, cell wall, cell membrane

ideally based on culture and sensitivity

first line - isothal and chloramphenacol - licensed in dogs, cat’s and rabbtis

melting ulcers - tetracycline - anticollaginase action

aminoglycosides and fluroquinolones - irritant, usually not ophthalmic preparations

31
Q

ophthalmic antifungals

A

azoles
polyenes
echinocandins

treatment for fungal keratitis and fungal abscesses

fungal abscesses - white in appearance, painful, can form burrow

expensive and irritant, confirm fungal infection with cytology
not eye preparations - not formulated to pH and osmolarity

fungal culture - 5-7 days minmum

32
Q

ophthalmic NSAIDs

A

ketorolac
bromfenac
voltarol

post operative inflammatory management
uveitis
analgesia

instead of or alongside topical steroids

33
Q

ophthalmic steroids

A

dexamethasone
prednisolone

indications, uveitis, immune mediated/non ulcerative corneal disease, blepharitis, episcleritis

don’t use on ulcerated cornea or infection - cause slow healing, corneal mineralisation and thinning

fluorescein scheck regularly if on topical steroids

34
Q

lacrimostimulators

A

stimulate tear production

ciclosporin
tacrilimus

less frequent use than tear substitues

35
Q

lacrimomimetics

A

tear replacements/lubricants

sodium hyaluronic acid
carbomer based gels

36
Q

ophthalmic pressure modulators

A

carbonic anhydrase inhibitors
beta blockers
prostaglandin analogs

indications - glaucoma

decrease aqueous humour formation or decrease outflow

side effects - local irritation, photophobia, blepharoconjunctivitis, hypokalemia in cats, miosis, uveitis, conjunctival hyperemia, iris darkening

37
Q

mydriatics

A

cholinergic antagonists

tropicamide - visualisation in exam, onset 1 hour, duration 12 hours
atropine - onset 1 hour, duration 3-5 days, 2 weeks in horses - prolonged relief rather than exam
cyclopentate - 1 hour onset, 2-5 day duration (newer)

pupillary dilation and relief of ciliary spasm

avoid in glaucoma

can have profuse salivation and occassional vomiting

birds - neuromuscular blocking agent instead

38
Q

solution …

A

drug totally dissolved in solvent

39
Q

suspension …

A

solid particles of active ingredient dispersed in liquid (shake before use)

40
Q

ointment …

A

semi solid gels and creams

enhanced contact time so less frequent use needed - better for large animals

41
Q

causes of acutely painful eye

A

ulcers
abscesses
lacerations/trauma
foreign bodies
uveitis
glaucoma
lens luxation

42
Q

species differences - enucleation

A

dog - oculocardiac reflex - acute drop in heart rate from pressure on globe
cat - don’t pull on optic nerve - damage at optic chiasm and contralateral vision loss
horse - standing surgery, nerve blocks
cattle - standing surgery, nerve blocks
rabbits - orbital venous plexus, bleeds a lot

43
Q

IOP measurement

A

useful in uveitis - low IOP

digital tonometry - using fingers - very subjective, compare the two eyes and whether fingers sink in
applantation tonometry - tonopen - force required to flatten cornea
indentation tonometry - tonovet - depth of indentation made by small plunger

44
Q

IOP ranges

A

dog/cat -
uveitis <10
normal 10-20
borderline 20-25
glaucoma >25

rabbit/horse -
uveitis <15
normal 15-25
borderline 25-30
glaucoma >30

45
Q

tear duct flushing

A

usually rabbits with dental disease

flush through duct with IV catheter
opening in medial canthus external to nictitating membrane
flush with saline

normal duct - out through nose
nasolacrimal duct blockage - back out around catheter

risk of corneal trauma or duct rupture

46
Q

grid or punctate keratotomy

A

promote corneal healing in indolent ulcers - removes loose and non-vitalised epithelium and stimulate release of inflammatory mediators

local anaesthetic
cotton bud to remove loose epithelium
grid lines with needle

risks of corneal puncture, pushing infection into cornea
contraindicated unless indolent ulcer

47
Q

wedge resection

A

removal of eyelid margin masses and ectopic cilia
also for shortening eylid for conformational issues

can be done for eyelid masses up to 30% of eyelid length

v shape for smaller masses, four sided wedge for larger areas

do eyelid margin with figure of 8 suture

48
Q

hotz-celsus procedure

A

to correct entropion

parallel cut in eyelid skin then crescent underneath
remove the inbetween skin
should be enough that when the edge are brough together the entropion is corrected

simple interrupted sutures

49
Q
A

CMS - term 1 (15 decks)

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