The Opaque Eye 2 Flashcards
What is corneal melting and what cuases it?
- collagenolysis
- Serin proteases and MMPs
- progresses v rapidly within hours or days
Is corneal melting local or widespread?
- EITHER
- perforation can occour in either case
- may have melted leaving a pothole so melting cannot be seen any more
What is a Descemetocoele?
- 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 *
What types of KCS are possible?
- 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
Possible presentation of 1* KCS?
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
How can KCS lead to perforamtion?
- 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
Early surgical options for 1* KCS?
> 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
medical tx of KCS?
- 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
Which species are corneal sequestrums commonly seen in? What are they?
- 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)
What is the pigment seen in feline corneal sequestrum?
Controversial - iron? melanin?
Etiology of feline corneal sequestrum?
- idiopathic
- trauma
- entropion
- grid keratotomy
> theories studied - tear film stability, corneal sensitivity, lipid abnormality, FHV1 role
Tx feline corneal sequestrum?
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
What sign means v chance of recurrence of feline corneal sequestrum?
- high risk of recurrence (within weeks/months)
- v chance of recurrence…
> if corneal BVs remain (eg. through graft)
> if completely removed
> entropion resolved
What are SCCEDs?
- 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)
Dx of SCCEDs?
- electron microscopy and IHC
Clinical picture with SCCEDs?
- loose epithelial edges
- under-running of fluorscin dye (pulsed saline test)
+- oedema, ocular pain,vascularisation - alwys r/o other causes (KCS, entropion, ectopic ciliulm)
Causes of SCCEDs?
may be associated with hx of minor trauma but NOT TRAUMATIC IN ORIGIN
- spontaneous
Tx SCCEDs?
- 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
How thick is the cornea?
0.5mm
How is a grid keratotomy (superficial grid scrape) performed?
- > 2mm apart
- 1-2mm into surrounding healthy tissue
- remain v superficial
- should not be able to see the grid!!
What is the newest tx for SCCEDs?
diamond burring
- sedation/GA
- bandage lens for comfort
Is tarsorrhaphy necessary with a bandage lens?
In dogs yes, covered 2/3 eye
- in cats not usually
Medical tx SCCEDs?
- 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)
Which virus may lead to corneal opacity?
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
How do FHV ulcer lesions appear?
- initially dendritic
- will spread and merge -> geographic ulcers more common
Which dye is sometimes advised for FHV ulcers?
Rose Bengal but not necessary!
- toxic to eyes
- can be seen with fluorescin
Tx FHV1?
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
What is feline acute bullous keratopathy?
- unknown aetiology
- acute development corneal oedema
> cornea becomes soft
> melting and perforation risk high
> prognosis worse if both eyes affected
requires rapid referral
Tx of feline acute bullous keratopathy?
REFER!!
- if cost prohibitive, attempt antivirals and tarsorrhaphy
Aetiologies of facial nerve paralysis?
- 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)
Clinical signs of facial nerve paralysis?
> 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
Tx facial n paralysis?
- tarsorrhaphy for 1-2 months
- protective collar
- topical Abx (fusithalmic BID/TID)
- preservative free visouc tears
