Download Equine cataracts and uveitis

Management of equine uveitis
and cataracts
Jonathan Pucket, DVM, MS, DACVO
Outline
• Equine uveitis
– Current theories
– Therapies
– Prognosis
• Equine cataracts
– Causes
– Therapy
– Prognosis
Uveal tract
Choroid
Iris
Ciliary body
www.nei.nih.gov
Blood-ocular barriers
• Blood-aqueous-barrier (BAB)
– Tight junctions in iris and ciliary body
• Blood-retinal-barrier
– Tight junctions between retinal pigmented
epithelial cells
• These barriers limit the immune response to
the internal aspect of the eye
– Immune privileged site
Ocular immunity
• No direct contact between systemic immune
system and inside the eye normally
• Problems arise when local inflammation
allows systemic immune system access
• Have to control inflammation and restore
barriers
Uveitis
• Inflammation of the uveal tract
–Anterior
• Iris and/or ciliary body
–Posterior
• Choroid
• +/- retina
–Panuveitis
• Both
Equine uveitis
• Causes
– Trauma
– Reflex- Corneal
disease
– Immune mediated
• Equine recurrent
uveitis (ERU)
– Neoplasia
– Tooth root abscess
– Infectious
• Foals- sepsis
• Rhodococcus
• Salmonella
• Leptospirosis
• EVA
• EIA
• Hoof abscess
Clinical signs of uveitis
• Blepharospasm
• Epiphora
• Hyperemia of
conjunctiva
• Corneal edema
• Corneal
vascularization
• Aqueous flare
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Fibrin
Hyphema
Miosis
Synechia
Cataract
Iris color change
Equine Recurrent Uveitis (ERU)
• Documented, cyclical bouts of uveitis
– Separated by periods of “remission”
– At least 2 observed episodes
• No set time between flares
• Different “triggers”
• Thought to be immune mediated
– Leptospirosis?
• Can affect anterior, posterior, or both
• #1 cause of vision loss among horses
ERU
• Aka
– Moon blindness
– Periodic ophthalmia
• Affects 2-25% of horses in USA
ERU
• Current theory
– Initial inciting uveitis allows access of T-cells
into eye
– T-cells activate and proliferate
– Attack leads to intraocular damage
• During attack, T-cells find more antigens to
become active against
– New T-cells in circulation to cause another
bout of inflammation
Forms of ERU
• Classic
– Most common form, outward clinical signs
– Attacks become increasingly severe
• Insidious
– No outward clinical signs
– Gradual and cumulative destructive effect
– Appaloosa and Draft breeds
• Posterior
– European horses, Draft breeds, and Warmbloods
Appaloosa ERU
• May have different pathogenesis
• 8.3 X more likely than all other breeds
combined
• Typically no overt signs of disease until
late
• Horses with “Foundation-type” or
“leopard” coat color more likely
Therapies for ERU
• Acute flare up
– Attempt to determine cause (make sure not
ulcer or stromal abscess as cause)
– Fluorescein stain and tonometry
– Topical anti-inflammatory drugs
• Topical NSAID?
• Topical Atropine (risk of colic)
• Topical Steroid (risk if becomes ulcerated)
– Systemic anti-inflammatory
• Flunixin meglumine
Therapies for ERU
• Periodic flare ups
–Manage as for acute flares
• Topical anti-inflammatory
• Topical atropine
• Systemic flunixin meglumine
Management practices
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Decrease dust
Increase insect and rodent control
Change bedding type
Split up immunizations
– Space ERU horse annual vaccines > 1 week apart
– Lepto vaccine NOT recommended for ERU horses
• Proper foot and dental care
• Optimal deworming schedule
Other therapies
• Daily aspirin
– No proven benefit at reducing flare ups
• Antibiotics
– Doxycycline and enrofloxacin
• Only in cases of presumed leptospiral infections
• Subconjunctival steroids
– Extreme caution must be used
– High risk of fungal keratitis
– Cannot “remove” steroid if problem arises
Other therapy
• Cyclosporine A (CSA)
– Absorption after topical application minimal
– Weak anti-inflammatory effect
• Strong immunosuppressant
– Prevents activation of T lymphocytes and
recurrence of uveitis
Surgery
• If flare ups are becoming more
frequent/severe, can consider surgery
• Uveitis must be “controlled” before
surgery
• CSA implant
– NC State laboratory
– Not FDA approved
Long term with CSA implant
• Horses had significantly fewer flare ups
– Mean 0.05 flare ups/month
– ~90% visual at 1-2 years after surgery
– 78.8% visual at last follow up compared to 44%
without CSA device
– 12% of Appaloosas lost vision compared to 81% w/o
• Replace device every 48 months
– Reactive T-cells may undergo anergy leading to
resolution of disease long term
Long-term outcome after implantation of a suprachoroidal cyclosporine drug delivery device in horses with recurrent uveitis
Brian C. Gilger,* David A. Wilkie,† Allison B. Clode,* Richard J. McMullen Jr.,* Mary E. Utter,‡ Andras M. Komaromy,‡ Dennis E. Brooks§ and
Jacklin H. Salmon*. Vet Ophtho 2010
EQUINE CATARACTS
Cataracts
• Estimated 5-7% of all horses have
cataracts
• Stages (percent of lens involved)
– Incipient- <15%
– Immature- 16-99%
– Mature- 100%
– Hypermature- Resorbing lens
Cataracts
• Causes
–Inflammation (#1 cause)
• ERU
–Hereditary/genetic
–Trauma
–Age related (Senile)
Cataracts
• Hereditary
–Usually show very early in life (foals)
–Certain breeds more common
• Thoroughbreds
• Morgan
• Quarter horse
• Rocky Mountain horses
Treatment
• Medical management
– No preventative available
– Topical atropine?
– Topical NSAID
• Flurbiprofen or Diclofenac
• Cataract dissolving drops?
• Surgery
Selection of surgical candidates
• Hereditary or congenital cataracts
• Uveitis cataracts are poor candidates
• Temperament
– Must allow frequent exams and medication
• Owner willing to return for follow-up
exams
– Owner must be dedicated
Cataract surgery in horses
• Visual compromise
– Even with artificial lens, every horse
undergoing surgery is considered visually
compromised
– Without lens they are very far-sighted
• Risks of glaucoma, corneal ulcers, retinal
detachment, and severe uveitis
Cataract removal
• Requires larger cataract surgery
equipment
– Not everyone has ability
• Placement of subpalpebral lavage line
(SPL)
Pre-operative Diagnostics
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CBC/Chem/Fibrinogen
Thoracic radiographs in foals
Ophthalmic exam
Ocular ultrasound
Electroretinogram (ERG)
Post-operatively
• Stall confinement for first 4 weeks
• Slow tapering of topical medications
• Rechecks
– Evaluating for long term complications
• Glaucoma
• Retinal detachment
• Uveitis
Summary
• Uveitis
– Occurs frequently
– Need to control quickly with medications
– ERU can be difficult to control
– CSA implant if repeated bouts
• Cataracts
– Uveitis cases not good candidates
– Surgery can improve vision
Questions?