The Opaque Eye 2 Flashcards

1
Q

What is corneal melting and what cuases it?

A
  • collagenolysis
  • Serin proteases and MMPs
  • progresses v rapidly within hours or days
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2
Q

Is corneal melting local or widespread?

A
  • EITHER
  • perforation can occour in either case
  • may have melted leaving a pothole so melting cannot be seen any more
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3
Q

What is a Descemetocoele?

A
  • partial bulging of Descemet’s membrane d/t erosion of epithelium and stroma
  • righ tbefore a perforation occours
  • does not uptake fluorescin (though wall of oedematous stroma around it will)
  • clear centre/black (pupil)
  • surgical emergency *
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4
Q

What types of KCS are possible?

A
  • evaporative d/t Maibomian gland dysfunction -> v lipid in the tear film
  • drug related (sulphonamides, etodolac, atropine)
  • anaesthetic and sedeatives (medetomidine) -> aqueous layer
  • 1* immune mediated KCS
    > majority affect aqueous portion of tear film
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5
Q

Possible presentation of 1* KCS?

A

2 trends
> Trend A: Biphasic Trend B: Typical
- 5yo
- females spayed
- mostly superficial, low incidence of ulcerative keratitis
- slowly progressive, + mucus accumulation and hyperaemia
+- vascularisation and pigmentation

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6
Q

How can KCS lead to perforamtion?

A
  • poor balance of construction/deconstruction diseased cornea
  • irritant constantly present
  • ^ thick mucoid discharge -> abnormal clearance
  • change in bacterial flora
  • inflame cells
    > collagenolysis, usually centrally
    > 2-7d
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7
Q

Early surgical options for 1* KCS?

A

> CLCT for central ulcers
- corneoimboconjunctival transposition with clear peripheral cornea
- allows clearer visual axis
conjunctival pedicle graft for peripheral ulcers
- faster
- doesn’t clear with time

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8
Q

medical tx of KCS?

A
  • topical ciclopsporin (lacrimogenic, doesn’t interfere with healing) or Tacrolimus
  • preservative free viscous tears
  • topical Abx (chloramphenicol (BS, god penetration, ~2 weeks; rarely need to use anything else, C+S if worried)
  • serum eyedrops (collect and freeze from animal, apply QID)
  • topical steroid providing no ulcers present
    > usually for life - client education and managing expectations
  • improvements 3/5 (mucus, redness, comfort, keratitis, tear reading) after 2 months tx
  • don’t get ttoo hung up on tear reading - if duct destroyed, cannot ^ so try and maintain
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9
Q

Which species are corneal sequestrums commonly seen in? What are they?

A
  • cats most common, dogs possible
  • spontaneous (any breed, pdf Persians)
  • uni or bilateral discolouration of the superficial stroma, progresses to black plaque w/ vascularisation, ulceration
  • may be central/paracentral cornea if spontaneous, or wherever irritation is eg. with entropion
  • mild to very painful (if epithelium not adhered to stroma = v painful)
  • needs to be removed (keratectomy)
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10
Q

What is the pigment seen in feline corneal sequestrum?

A

Controversial - iron? melanin?

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11
Q

Etiology of feline corneal sequestrum?

A
  • idiopathic
  • trauma
  • entropion
  • grid keratotomy
    > theories studied
  • tear film stability, corneal sensitivity, lipid abnormality, FHV1 role
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12
Q

Tx feline corneal sequestrum?

A

Surgical
- superficial keratectomy +- bandage lens +- tarsorrhaphy
- SK + grafting (conjunctival pedicle, corneoconjunctival transposition, biosist) ?grafting effectiveness
> post surgery
- topical Abxx until re-epithelialisation
- preservative free viscous tears

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13
Q

What sign means v chance of recurrence of feline corneal sequestrum?

A
  • high risk of recurrence (within weeks/months)
  • v chance of recurrence…
    > if corneal BVs remain (eg. through graft)
    > if completely removed
    > entropion resolved
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14
Q

What are SCCEDs?

A
  • spontaneous chronic corneal epithelial defects
    = boxer ulcers, indolent unlcers, non healing ulcers
  • possible in cats but not described as in dogs
  • extra hyaline membrane between BM and epithelium -> whole epithelium sloughing (interference with epithelial adherence to stroma NOT basement membrane dystrophy)
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15
Q

Dx of SCCEDs?

A
  • electron microscopy and IHC
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16
Q

Clinical picture with SCCEDs?

A
  • loose epithelial edges
  • under-running of fluorscin dye (pulsed saline test)
    +- oedema, ocular pain,vascularisation
  • alwys r/o other causes (KCS, entropion, ectopic ciliulm)
17
Q

Causes of SCCEDs?

A

may be associated with hx of minor trauma but NOT TRAUMATIC IN ORIGIN
- spontaneous

18
Q

Tx SCCEDs?

A
  • debridement (all loose epithelium and hyaline plaque)` +- bandage lens
  • grid keratotomy (can -> sequestrum in the cat)
  • keratectomy (100% healing rate! 14d)
  • nictitans flaps have NO special healing affect
19
Q

How thick is the cornea?

A

0.5mm

20
Q

How is a grid keratotomy (superficial grid scrape) performed?

A
  • > 2mm apart
  • 1-2mm into surrounding healthy tissue
  • remain v superficial
  • should not be able to see the grid!!
21
Q

What is the newest tx for SCCEDs?

A

diamond burring

  • sedation/GA
  • bandage lens for comfort
22
Q

Is tarsorrhaphy necessary with a bandage lens?

A

In dogs yes, covered 2/3 eye

- in cats not usually

23
Q

Medical tx SCCEDs?

A
  • topical chloramphenicol 3x daily
  • serum eyedrops 3-4x daily
    > re-evaluate every 2 weeks
  • remove tarsorrhaphy and bandage lend on 1st revisit
  • may need to re-debride (topical anaesthetic)
24
Q

Which virus may lead to corneal opacity?

A

FHV1

  • lives in trigem ganglion and corneal tissue
  • infected in kittenhood (cat flu)
  • > symblepharon in kittens
  • corneal ulcerative dz can be severe
  • recrudescence d/t stress
25
Q

How do FHV ulcer lesions appear?

A
  • initially dendritic

- will spread and merge -> geographic ulcers more common

26
Q

Which dye is sometimes advised for FHV ulcers?

A

Rose Bengal but not necessary!

  • toxic to eyes
  • can be seen with fluorescin
27
Q

Tx FHV1?

A
Anti-virals
- Static not cidal 
- irritating topically
- mostly toxic!!!
> idoxuridine and TFT (triflurothymidine) 
- specificity for FHV1 in utero
- tolerance? no trials but TFT ok, Idox bad enerally
> cidofovir
- v severity clinical signs and shedding 
> Pen-, Gan- and A- cyclovir
- toxic orally, liver kidney, BM 
- topically none trialled 
> FAMCYCLOVIR SAFE ORALLY!!! YAY
- peniciclovir active metabolite 
- SID up to target dose (don't reach target!) 
- can be used long term
28
Q

What is feline acute bullous keratopathy?

A
  • unknown aetiology
  • acute development corneal oedema
    > cornea becomes soft
    > melting and perforation risk high
    > prognosis worse if both eyes affected
    requires rapid referral
29
Q

Tx of feline acute bullous keratopathy?

A

REFER!!

- if cost prohibitive, attempt antivirals and tarsorrhaphy

30
Q

Aetiologies of facial nerve paralysis?

A
  • viral (calici and FHV1)
  • oritis media (tympanic bulla)
  • ear canal avulsion (trauma)
  • severe otitis externa
  • ear canal neoplasia
  • TECA with LBO
  • idiopathic (immune mediated? )
  • as part of polyneuropathy
    > cats
  • chronic otitis media tx (VBO) low risk of FN paralysis
    > permenant in some cases (70% ECA, 40-70% TECA/LBO though should be less nowadays)
31
Q

Clinical signs of facial nerve paralysis?

A
> loss of blink (usually temporary) 
- systemic Abx and/or myringotomy and topical ear medication 
> interpalpebral fissue ulceration 
- superficial but can deepen/melt 
- sequestrum formation possible
32
Q

Tx facial n paralysis?

A
  • tarsorrhaphy for 1-2 months
  • protective collar
  • topical Abx (fusithalmic BID/TID)
  • preservative free visouc tears