Uveitis, Ocular Conditions and Ultrasound Flashcards
Acute Uveitis Signs
- Pain (blepharospasm + epiphora + photophobia)
- Miosis
Sometimes also: - “Fuzzy” iris
- Aqueous flare
- Hypopyon/hyphaema
- Corneal oedema
- Corneal vascularization
- Hypotony (low IOP: 5-12mmHg)
Chronic Uveitis Signs
(Post uveitis damage)
* Pupillary irregularity
* Synechiae/iris rests
* Cataract
* Corpora nigra atrophy
* Iris hyperpigmentation
* Vitreal haze/infiltrate
* Retinal degeneration
* Retinal detachment
* Glaucoma
Uveitis Categories
Anatomical:
* Anterior uveitis: iris and ciliary body * Posterior uveitis: choroid
* Chorioretinitis: choroid and uvea
* Panuveitis: all uveal components
Aetiologic:
* Ocular trauma/inflammation
* Haematogenous infection/sepsis
* Auto-immune disease
Incidence Categories:
- 1° vs Equine recurrent uveitis
Uveitis Causes - Ocular Trauma/ Inflammation
- Commonest
Also often seen in cases of: - Non-ulcerative keratitis
- Blunt ocular trauma
- Usually manifest as pain and miosis
- Always assess pupil size in ulcer cases
- Treat uveitis specifically (in addition
to the ulcer) - Iris/ciliary spasm contribute to the ocular pain
- Risk of synechiae if not treated
Uveitis Causes - Haematogenous Infection/ Sepsis
- Sometimes seen in cases of:
- Septicaemia/ bacteraemia/
endotoxaemia - Bilateral
- **foals, occasionally adults
- not very painful and resolves well in foals
- more problematic in adults, especially when painful
Uveitis Causes - Autoimmune - Equine Recurrent Uveitis
- Rare in UK, ***USA
- Appaloosas, Draft breed, Polo ponies, Warmbloods
- 1st = Leptospira
- Recurrent episodes= autoimmune disorder
- Recur and progress
- Clinical signs are no different from other causes except:
- Previous chronic changes along with current acute changes (recurrent nature)
- Begins in one eye -> bilateral
- -> blindness
Types of Equine Recurrent Uveitis
- Classic ERU – active inflammatory episodes -> periods of minimal observable ocular inflammation. Quiescent phase -> further and increasingly severe attacks of uveitis.
- Insidious ERU – low grade inflammation , not as outwardly painful. Gradual and cumulative destructive effect. appaloosas and draft breeds.
- Posterior ERU – inflammation predominantly in the vitreous, retina and choroid. **warmbloods, draft breeds, horses imported from EU.
Uveitis Exam
- PAIN + MIOSIS = UVEITIS!
- Difficult to examine a painful eye properly unless:
- In a darkened stable
- Sedated
- Auriculopalpebral nerve block
- Bright pen torch
- Ophthalmoscope
Uveitis - Tx - Acute cases
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 outp
Uveitis - Tx - Acute cases
Anti-Inflammatories
NSAIDs
* Systemic: Flunixin 1.1mg/kg q12-24h
* Topical: Bromfenac (“Yellow”) 0.9mg/mL eye drops q12h
Glucocorticoids (not if 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
Uveitis - Tx - Acute Cases
Keep out of sunlight
- Photophobic
- Especially if used atropine (can be very long-acting in horses)
- Facemask, dark stable
Uveitis - Tx - Acute Cases
Topical Anti-inflam
- Prednisolone acetate 1% (Pred
Forte) preferred - 2-4 x daily or more frequently if
needed - Always make sure there’s no ulcer
before prescribing! - Care if oedema
Uveitis - Tx - Chronic Cases
Simple approaches:
- Decrease recurrent episodes
- 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
- Facemask
Uveitis - Tx - Chronic Cases
Complex Approach:
Subscleral cyclosporin implant
* USA
Vitrectomy
* Germany
Low dose intravitreal gentamicin
* International
* Simpler and similar success
Enucleation
Enucleation
- Standing or GA
- 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
Glaucoma - Pathophysiology
- Uncommon
- 2° to uveitis
- Aqueous is produced by ciliary body and removed via:
- Conventional outflow: iridocorneal angle (MINOR
pathway in horses) - Unconventional: uveoscleral absorption (MAJOR pathway in horses)
Glaucoma - Clinical Signs
- Mature horse
- Hx of uveitis
- Focal or complete corneal oedema
- Usually painless (unless active uveitis)
- Mydriasis? (unless active uveitis)
- Corneal striae?
- Exophthalmos?
- Signs of previous uveitis?
Glaucoma - Dx
- Increased IOP (28mmHg)
- Tonometry
- Ultrasound - high frequency linear probe
Glaucoma - Tx
Medical:
“Cosopt”; combination of:
* Timolol maleate 0.5% - β-adrenergic antagonist:
* Decreases ciliary body flow and aqueous production
* Dorzolomide 2% - carbonic anhydrase II inhibitor:
* Decreases aqueous production
Surgical:
* Transscleral cyclophotocoagulation (TSCP)
* Laser destruction of ciliary body to decrease aqueous production
Corpora Nigra Cysts
- Smooth masses on the corpora nigra
- Dorsal +/- ventral
- Uni/bilateral
- Confused w melanoma
- Differentiate w ultrasound
- Cyst are fluid-filled, melanoma solid
- Monitor growth with ultrasound
- Very rarely of any clinical significance
- If treatment indicated (rare):
- Laser removal
- Standing transcorneal aspiration of primary iris cysts (STAPIC)
Ocular Ultrasound Technique
- 7.5Mhz+
- Linear transducer
- Low-tech equipment * Sedation
- Transpalpebral
- Gel on eyelid
Layer Thickness
Cornea
Anterior Chamber
Lens
Vitreous
Cornea - 1mm
Anterior Chamber - 3-5mm
Lens - 10-15mm deep
Vitreous - 15-20mm deep
Retina/choroid/sclera - 2-3mm (anechoic)
Cataracts
- Incipient cataracts echogenicity <5% of lens
- Immature cataracts echogenicity 5-95% of lens
- Mature cataracts echogenicity >95% of lens
- Hypermature cataracts lens shrinkage
- Intumescent cataracts increased lens size
