Equine Recurrent Uveitis

Question 1

Leading cause of Blindness in horses

Answer 1

ERU

Question 2

Uveitis starts as

Answer 2

blood-ocular barrier compromise

Question 3

Chemical and cellular mediators that leak from vessels

Answer 3

1. PMNs
2. then Lymphocytes
3. Inflammatory cytokines

Question 4

Consequences of vascular permeability (5)

Answer 4

1. Formation of exudates that adhere to post iris, CB, and choroid
2. Inclusion bodies in non-pigmented ciliary epithelium
3. Exudates interfere with uveal function
4. Exudates accumulate around ciliary processes and iris
5. Iris and ciliary body become swollen, edematous and infiltrated with inflammatory cells

Question 5

ERU Lymphocyte infiltration (6)

Answer 5

1. Heavy influx into uveal/other eye tissues
2. Clusters resembling follicles in ciliary body
3. T-cells predominate, MHC Class II reactive
4. inflammation of choroid
5. Tissue damage from cytokines, immune interaction
6. Altered function=loss blood supply to retina

Question 6

Retinal Pathology (5)

Answer 6

1. Lympocyte infiltration at the Retinal pigmented epithelium
2. Thickened inner limiting membrane
3. Degeneration of photoreceptors
4. Subretinal exudate from choroidal vasculature
5. Retinal folds and detachment at retinal pigmented epithelium

Question 7

Signs of acute Uveitis (5)

Answer 7

1. Hypopion
2. Hyphema
3. Aqueous flare
4. Fibrin
5. Keratic Precipitates

Question 8

Signs of chronic Uveitis (12)

Answer 8

1. Synechiae
2. Cataract
3. Iris color change
4. Corneal vacularization
5. Permanent corneal edema
6. Corneal bullae and ulcers
7. Corpora nigra atrophy
8. Band keratopathy
9. butterfly lesions (chorioretinal scars)
10. Glaucoma
11. Lens lux
12. Phthisis bulbi

Question 9

Glaucoma CS (5)

Answer 9

1. Corneal edema
2. Mydriasis
3. Haab’s striae-breaks in descemet’s mem
4. Buphthalmia
5. Accompanying uveitis

Question 10

Phthisis bulbi (2)

Answer 10

1. Shrunken globe

2. End-stage something….

Question 11

Classic Uveitis

Answer 11

1. CS of acute uveitis
2. Episodic recurrence, variable intervals
3. Gets chronic signs over time
4. Unilateral I think

Question 12

Likely pathogenesis of ERU (3)

Answer 12

1. Immune cells enter eye and recognize self antigen
2. Recurrent episodes likely from ‘epitope spreading’
3. Persistence of organism doesn’t commonly play a role

Question 13

Appies more likely to suffer uveitis than other breeds by

Answer 13

8. 3 times
   - sparse main/tail, light pigment
   - fewer spots less ERU (Leopards)

Question 14

Risk factors for Lepto (5)

Answer 14

1. Pasture access to cows, pigs, deer
2. Close proximity to ponds/rivers
3. Use of pond water for drinking
4. Rat infestation
5. Heavy rainy season

Question 15

Theories of lepto link

Answer 15

1. Due to direct toxicity - initially yes
2. Autoimmune disorder triggered by molecular mimicry-probably
3. Leptospira modulating immune response-possibly

Question 16

Percentage of eyes with uveitis losing sight if Lepto + (11 yrs): (4)

Answer 16

1. lepto positive and appy: 100%
2. lepto neg and appy: 71%
3. lepto pos and non appy: 52%
4. lepto neg non appy: 34%

Question 17

Steroids and uveitis

Answer 17

> 25% of horses with uveitis suffer corneal ulcers over time (Steroid treatment can be dangerous)

Question 18

Outcome of Uveitis (3)

Answer 18

1. NO MATTER WHAT, many uveitic horses go blind
2. Some horses have to be euthanized
3. Some horses can live on as family pets

Question 19

Sequelae of uveitis (7)

Answer 19

1. > 25% horses suffer corneal ulcers
2. 25% have corneal scars
3. 6% develop calcium plaques on cornea (difficult to treat)
4. Posterior synechia
5. lens lux
6. cataracts
7. glaucoma

Question 20

Pars Plana Vitrectomy (4)

Answer 20

1. Sucks out vitreous
2. Obtain sample for PCR, culture
3. Decrease vitreal opacities
4. Reduces severity and number of uveitis episodes in humans

Question 21

Vitrectomy case selection (4)

Answer 21

1. Recurrent uveitis despite treatment
2. Minor intraocular changes
3. ERU causes by persistent intraocular lepto
4. Vitreal opacities

Question 22

Vitrectomy contraindicated if

Answer 22

extensive posterior synechiae

Question 23

Complications of vitrectomy (7)

Answer 23

1. Recurrence of uveitis
2. Post surgical uveitis-expected
3. Cataract
4. vitreal hemorrhage
5. Hyphema
6. Anterior segment fibrin
7. Retinal detachment

Question 24

Cyclosporine implant (7)

Answer 24

1. Biodegradeable, implanted w/in suprachoroidal space
2. Blocks IL-2 production
3. Minimizes T lymphocyte production
4. Induces immunosuppression
5. Delivers 4 micrograms/day for up to 5 years
6. 81% have less inflammation and attacks
7. 87% are visual at 14 moths postop

Question 25

CsA implant candidate selection (5)

Answer 25

1. Good response to traditional medical therapy
2. Lack concurrent ocular dz (glaucoma, cataract)
3. Little to no active inflammation (PRETREAT)
4. Frequent relapse uveitis or early relapse ERU after d/c meds
5. Educated owner

Question 26

Vaccine recommendations for Lepto

Answer 26

1. If normal eyes and seronegative for lepto
2. High risk farms
3. No other drugs or vaccines on same day

Question 27

Salvage proc

Answer 27

1. Enucleation
2. Intrascleral prosthesis (ISP)
3. Ciliary body ablation (for glaucoma) 25-100 mg gentamycin