Week 2- Uveitis (Equine Opthamology) Flashcards
What are the 3 main parts of the uvea?
- Iris
- Ciliary Body
- Choroid
What are the main clinical signs of uveitis?
- Pain
- Miosis
- Aqueous flare
- Corneal Oedema
- Corneal vascularisation
- Hypotony (low pressure)
What are the main signs of chronic uveitis?
- Pupil irregularity
- Cataract
- Synechiae
- Nigra atrophy ( loss of cells in the substantia nigra)
- retinal degeneration/ detachment
What is the most common cause of uveitis in the UK?
Ocular trauma and inflammation
How does ocular trauma always manifest?
manifests as pain and miosis
What is there a risk of if ocular trauma is not treated?
Risk of synechiae
When is haematogenous infection/ sepsis usually seen?
Sometimes seen in cases of:
* Septicaemia/bacteraemia/endotoxaemia
* bilateral
* often not painful and resolves well in foals
* may be more problematic in adults
What horse breeds most commonly get auto-immune uveitis?
- Appaloosa
- Draft Breeds
- Polo ponies
- Warmbloods
What are initial episodes of auto-immune uveitis associated with?
specific serovars of Leptospira
* tendency to recur and progress
What are the most common clinical signs of auto-immune uveitis?
Often signs of previous chronic changes along with current acute
changes (recurrent nature)
* Generally begins in one eye but often becomes bilateral
* Significant risk of eventual blindness
What is classic ERU?
Active inflammatory episodes followed by periods of minimal observable ocular inflammation. Quiescent phase generally followed by further and increasingly severe
attacks of uveitis.
What is insidious ERU?
– low grade inflammation , not as outwardly painful. Gradual and cumulative
destructive effect. Most commonly seen in appaloosas and draft breeds.
What is posterior ERU?
inflammation predominantly in the vitreous, retina and choroid. Most
common in warmbloods, draft breeds and horses imported from Europe.
How would you treat miosis with mydriatics?
1% atropine eye drops, q2h until pupil dilated
* Further doses if necessary to maintain mydriasis (1-2 x daily?)
* NB. Can sometimes cause colon impaction
* Carefully monitor faecal output
How would you treat uveitis with NSAIDS?
Systemic: Flunixin 1.1mg/kg q12-24h
* Topical: Bromfenac (“Yellow”) 0.9mg/mL eye drops q12h
How would you treat uveitis with glucocorticoids?
only use if not ulcerated
Topical: Prednisolone acetate 1% (“Pred Forte”) (good ocular penetration) q1-12hours
* Systemic: Dexamethasone 0.05-0.10mg/kg IV q24h, Prednisolone 1mg/kg PO q24 h
What is the most important aspect of uveitis treatment?
Topical anti-inflammatory treatment is probably the
most critical component
* Prednisolone acetate 1% (Pred Forte) preferred
How often do you need to apply topical anti-inflammatory treatments to the eye?
2-4 x daily or more frequently if needed
* Ophthalmic dexamethasone could be used but Maxitrol
(dex, neomycin, Polymixin B) isn’t ideal as has AB in it
* Always make sure there’s no ulcer before prescribing
How would you treat chronic/ quiescent ERU cases?
NSAIDs
* Systemic: phenylbutazone/suxibuzone PO q24h
* Glucocorticoids (not if ulcerated)
* Systemic: Prednisolone 0.5-10.mg/kg PO q 24-48h
* Topical prednisolone acetate 1% (“Pred Forte”) q 12-48h (as often as necessary)
* Keep out of sunlight, wind, dust, etc….
* Facemask
What is the main aim of treating a chronic/ quiescent ERU case?
Aim to decrease likelihood of recurrent episodes in ERU
What is the main aim of managing/ treating uveitis?
- Aim to decrease likelihood of recurrent episodes
- Sub-scleral cyclosporin implant
- Mainly USA
- Vitrectomy
- Mainly Germany
- Low dose intravitreal gentamicin
- International
- Simpler and similar success
- Enucleation
- NB. ERU may become bilateral
What analgesia is used during enucleation?
Topical local anaesthesia (tetracaine or
proparacaine) auriculopalpebral nerve
block, supraorbital (frontal) nerve block,
retrobulbar nerve block & ring block to
ensure analgesia of the peri-orbital skin
What are the two ways Aqueous humour is removed in the horse?
Conventional outflow: iridocorneal angle (MINOR
pathway in horses)
* Unconventional: uveoscleral absorption (MAJOR
pathway in horses)
What does post-inflammatory scarring and cell damage result in?
poor drainage and glaucoma
What is the clinical presentation of glaucoma in horses?
- History of uveitis
- Focal or complete corneal oedema
- Usually painless
- Signs of previous uveitis
How would you diagnose glaucoma?
- Applanation tonometry (IOP)
- Ultrasound- demonstration of globe enlargement
- globes should be identical in diameter
What is the function of Timolol Maleate?
0.5% - β-adrenergic antagonist:
* Decreases ciliary body flow and aqueous production
glaucoma treatment
What is the function of Dorzolomide?
2% - carbonic anhydrase II inhibitor:
* Decreases aqueous production
Glaucoma treatment
What is the surgical treatment for glaucoma?
Transscleral cyclophotocoagulation (TSCP)
* Laser destruction of ciliary body to decrease aqueous production
What is a corpora nigra cyst?
- Smooth masses on the corpora nigra
- Could be confused with a melanoma
- If treatment indicated= laser removal STAPIC
What is the ocular ultrasound technique?
7.5Mhz+
* Linear transducer
* Low-tech equipment
* Sedation
* Transpalpebral
* Gel on eyelid
