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Flashcards in Problem solving - Red eye + CS Deck (73):
1

What are the 3 main steps in working through a red eye case?

- where, what, how
- work-up
- treatment plan

2

Where might you see redness in the eye?

- eyelids
- conjunctiva/ episclera/ sclera
- third eyelid
- cornea
- anterior chamber
- anterior uvea
- posterior uvea and retina with funduscopy
- retrobullar area (cannot see directly)

3

What is the uvea?

3 parts:
ANTERIOR: iris and ciliary body
POSTERIOR: choroid

4

What should you consider for how you get a red eye?

- whole eye and adnexa
- from outside to inside

5

What are the 3 most important things to consider for how you get a red eye?

- what structures are in the tissue i am thinking of?
- how would each tissue respond to insult?
- how would changes in one tissue affect the other tissues around it?

6

What could cause a red eyelid?

- skin, meibomian glands, conjunctiva
- hyperaemia/ swelling/ ulcers/ crusts/ loss of hair
- dermatitis (various causes)
- Meibomian gland (infxn, neoplasia, granuloma)

7

What are eyelids intimately associated with? 2

- cornea
- tear film
(problem could be loss of protective effect, loss of oily part of tear film from meibomian glands, contact problem). Leads to:
- ulcers
- epiphora
- hyperaemia
- vascularisation

8

What is the conjunctiva?

Mucous membrane lining the eyelids, TE, sclera. Ends at the limbus where the 'white' meets the cornea = the corneoscleral junction

9

Describe conjunctival BVs

- dichotomous branching
- very sensitive to surface irritation
- dilatation of BVs and separation of ECs --> hyperemia and oedema (chemosis)
- show with superficial dz
- caution: possibly also episcleral BVs

10

When do episcleral BVs show prominently?

- these are deep BVs
- show with intraocular dz
- caution: possibly also conjunctival BVs

11

What is the episclera?

- CT under the conjunctiva
- up to limbus
- different looking BVs with no dichotomous branching, larger, meander (curves), signal intraocular disease mostly (glaucoma and uveitis) or sometimes severe/ chronic surface irritation

12

What is the sclera?

- the true white of the eye
- fibrous tunic
- continuous with cornea via limbus
- collagen fibres and fibroblasts
- Emisaria (= holes for BVs and nn)

13

How can you get redness in the TE?

- same as for the conjunctiva
- many lymphoid follicles in bulbar side (also palpebral side, very prominent in young animals and allergies, accompanied by hyperaemia). Can --> follicular conjunctivitis
- T-shaped cartilage core (holds TE against eye, can curl and cause an outward fold)
- contains lacrimal gland (30% tear film aqueous part), can prolapse + inflammation --> cherry eye)
- BVs are dichotomous and branching (n.b. TE doesn't have episcleral BVs).

14

List the 4 corneal layers

EXTERNAL:
epithelium
stroma (thickest part, hydrophilic so uptakes fluorescein)
descemet's membrane
endothelium (contacts air, eyelids, tears, bacteria/dust)
INTERNAL

15

Define descemetocoele

where descemet's membrane doesn't uptake stain due to a herniation in it, usually corneal wound or deep ulceraiton

16

Outline corneal oedema pathophysiology

stroma portion is hydrophilic so if there is a problem with epithelium, stroma will swell. It is essentially stromal overhydration.

17

How does the stroma stay relatively dehydrated?

Though action of:
- epithelium
- endothelium (which actively pumps fluid back into the AC)

18

3 main methods of damage to cornea

- loss of epithelium
- damage to endothelium
- vascularisation (leakage) of stroma

19

Structures that define the AC

iris, lens, cornea (endothelium), conjunctiva, ICA

20

What fills the AC?

Aqueous humor

21

Outline flow of A.H.

from CB, into posterior chamber, through pupil to AC then out at ICA.

22

Name 2 dz affecting the AC

- Glaucoma (ICA closure/ clogging of the ICA -> decreases uveoscleral outflow and increases IOP)
- Uveitis : increases uveoscleral outflow and decreases IOP

23

Name the 2 parts of the anterior uvea

CB and iris

24

What is the posterior uvea?

choroid

25

Outline uvea structure?

mesh of blood vessels, pigmented

26

Other structures in the uvea

ANTERIOR
- mm (constricotr, dilator and CB mm)
- anterior blood ocular barrier (separates blood and aquoeous)
POSTERIOR
- tapetum lucidum

27

What happens if the blood ocular barrier (BOB) of the uvea is broken?

you can have recurrent uveal / eye problem for the rest of your life.

28

What happens if the uveal epithelium separates?

- leakage into AC of keratic precipitates, hypopion, hyphema, fibrosis
- leakage around lens known as 'snow banking'

29

What is adhesion of iris to anterior lens?

posterior synechiae

30

Define PIFM

Preiridal fibrovascular membrane:
- grow over iris and in pale irises are visible as rubeosis
- may lead to blinding to blinding of the eye (hyphema)
- closure/blockage of ICA - a type of secondary glaucoma

31

Define rubeosis iridis

BVs on iris (i.e. neovascularisation of iris)
Possible ddx:
- FIP, FIV, FeLV

32

When might sudden decompression of the anterior uvea occur?

- inflammation
- anterior synechiae
- bleeding form iris and ICA (retrograde flow of aqueous followed by blood)

33

Define iris bombe

apposition of iris to lens or anterior vitreous, preventing aqueous from flowing from posterior to anterior chamber.

34

How do anterior synechiae form with sudden decompression?

Corneal perforation, iris and lens damage (bleeding, cataract). As FB falls off, it causes iris prolapse and an adhesion of the pupillary edge of the iris to the posterior cornea.

35

Why are anterior and posterior uvea often simultaneously affected?

they are continuous

36

Define panuveitis

when posterior and anterior uveitis occur together

37

Define hyphema

bleeding into anterior segment of the eye

38

What might you see with posterior uveitis? 3

- panuveitis
- hyphema into AC
- retinal detachment

39

What happens if there is bleeding into the posterior segment?

not called hyphema (unlike AC) but causes retinal detachment

40

How can there be inflammation and ifxn in retrobulbar area?

- tooth removal and elevator enters posterior segment
- stick injuries in dogs --> retrobulbar abscess
- middle ear abscess
- conjunctival FB that travels posteriorly
- haematogenous spread
- blunt trauma - bleeding
- parasitic disease

41

Which tissues can be affected by neoplasia in retrobulbar area?

- extraocular mm
- optic nn (meninges, CSF)
- SNS and PNS, sensory nn
- BVs
- lacrimal gland
- zygomatic salivary gland
- CT (e.g. bones)
- nearby anatomy (soft tissue with incomplete orbits, sinuses)

42

What do retrobulbar area problems lead to? Which 4 lead to red eye?

- altered position of eye within orbit -> dry -> red
- altered relationship with eyelids -> red eye
- possible increased pressure around eye (mass effect) -> red eye
- swelling/ infxn of tissues around it, including conjunctiva -> red eye
- vision loss (ON)
- pupillary problems
- restriction of ocular movement

43

Name 3 ancillary ophthalmology tests

- IOP test
- Jones
- Fluorescein

44

What do you use transillumination/slit examination for?

anterior segment (AS) visualisation

45

Uses of DO

- nuclear sclerosis vs. cataract
- looking at pupillary shape/symmetry

46

How can you look at the fundus?

IO (monocular and binocular)

47

When does an eye have a blue hue?

when corneal thickening causes collagen fibres to fall out of arrangement as photons of light cannot pass through as they normally would.

48

What can corneal oedema cause?

- ulcer
- uveitis
- glaucoma

49

Define ectopic cilia

usually one hair in one location, often central upper eyelid on conjunctival side of eyelid, grows in towards eye

50

Define distichiasis

can be single, usually numerous, not an extra line of eyelashes as the name means in latin, actually fur, NOT eyelash that exits from a meibomian gland near the TE.

51

Define trichiasis

normal hair that is poking you in the eye

52

What is Fucithalmic?

a topical AB that contains fucidic acid (stops protein synthesis)

53

T/F: distichiae can cause corneal abrasions but rarely ulers

True

54

If a STT has a reading of 15mm/min with an eye with an ulcer, what would this indicate?

technically this falls within normal limits for tear production, however an eye with an ulcer should have increased tear production, therefore this reading (especially as it is on the low end of normal), may indicate a problem

55

If there is positive uptake of fluorescein by ulcer walls and ulcer beds, which ddx can be eliminated?

descemetocoele

56

How do cocker spaniels and weimeraners/ bulldogs differ in distichiae?

COCKER SPANIELS: long soft distichiae, may not cause (much) irritation
WEIMERANER/ BULLLDOG: short, stiff hairs, likely to cause irritation

57

Tx - distichiasis

* electrolysis - a current comes out of a probe --> radicals that destroy hair follicle epithelium
- cryotherapy
- wedge resection (but likely too many hairs, only really for ectopic cilia)

58

What is the commonest form of KCS?

primary immune-mediated KCS, can be uni/bilateral

59

T/F: dogs aren't particularly sensitive to FBs in the eye

True - their corneas aren't particularly sensitive (cats more so).

60

When might corneal oedema be seen?

epithelial disease or endothelial disease. endothelial disease may be caused by glaucoma or uveitis. IOP tanometry to differentiate.

61

Ddx - ulcerative disease in (young) dogs

- ectopic cilium of upper eyelid
- FB trapped under TE
- entropion
- distichiasis
- trauma
- KCS
- primary ulcers: SCCEDs

62

When might you perform surface ocular cytology?

when you suspect LPI (pannus), perhaps with an obvious cellular infiltrate (white/yellow abscess)

63

If a descemetocoele is present, what should you do?

Refer, don't attempt to sample for surface ocular cytology

64

When to perform surface culture and sensitivity?

with a melting cornea or a corneal abscess. DON'T sample with descemetocoele.

65

Medical tx for KCS

- Optimmune (BID)
- preservative free viscous tears

66

Define OU

oculus uterque = both eyes

67

Define OD

oculus dexter = right eye

68

Define OS

oculus sinister = left eye

69

Sx - peripheral ulcer

conjunctival pedicle grafting

70

Sx - central ulcer

corneolimboconjunctival transposition (CLCT)

71

Why might atropine be bad to give to cats?

foul taste - cats are very sensitive to this and foam at the foam where food accumulates on lips/chin, huge volumes. In cats, give as ointment rather than injection to decrease the risk of it entering the mouth

72

T/F: anything you put in the eye can delay ulcer healing

True - especially preservatives

73

How does atropine help the eye with reflex uveitis?

this eye has a spastic iris. Atropine relaxes this --> pupil dilation and decreased pain.