Uveal Disorders

Question 1

What are the clinical signs of ACUTE anterior uveitis?

Answer 1

Blepharospasm/Epiphora
Miosis
Aqueous flare
Hypopyon/Hyphema

Question 2

What are the clinical signs of CHRONIC anterior uveitis?

Answer 2

Acute signs +
-Cataract
-Retinal detachment
-Secondary glaucoma
-Phthisis bulbi

Question 3

Equine Recurrent Uveitis (ERU) has other names, which are:

Answer 3

Moon Blindness
Periodic ophthalmia

Question 4

What are the two features of ERU?

Answer 4

Classic vs. Insidious

Question 5

What are the 3 main etiologies of ERU?

Answer 5

1. Leptospirosis (#1!)
2. Onchocerca cervicalis (equine neck threadworm)
3. Immune-mediated/hypersensitivity

Question 6

Which breed of horse is predisposed to ERU?

Answer 6

Appaloosas

Question 7

What component of the blood causes the eye to appear green/yellow?

Answer 7

Bilirubin

Question 8

What are the clinical finding of ERU for both the anterior and posterior segments?

Answer 8

Anterior: miosis, aqueous flare, hypopyon, posterior synechia
Posterior: Vitreal debris/liquefication, chorioretinitis, retinal detachment

Question 9

The classic “butterfly” lesion is indicative of what chronic change seen with ERU?

Answer 9

Retinal scarring

Question 10

What are the methods of diagnosing ERU?

Answer 10

1. Serology (lepto titers)
2. Conjunctival biopsy (onchocerca larvae)
3. Ocular ultrasound
4. CBC/Chem (rarely useful)

Question 11

What are the goals of therapy for managing ERU?

Answer 11

Control ocular inflammation, preserve vision, maintain comfort

Question 12

What are the methods of medical therapy for ERU?

Answer 12

1. Systemic NSAIDs (Banamine)
2. Topical corticosteroids (Fluoroscein stain before)
3. Topical atropine
4. Systemic antibiotics (not super effective)

Question 13

What are the contraindications for using topical atropine?

Answer 13

1. Glaucoma
2. Dry eye (dogs)

Question 14

What are the surgical therapies for ERU?

Answer 14

1. Cyclosporine implants
2. Vitrectomy
3. Intravitreal gentamycin

Question 15

What is the downside to performing a vitrectomy as a surgical treatment to ERU?

Answer 15

High incidence of cataract formation

Question 16

Other recommendations for management of ERU?

Answer 16

1. Environmental modification (change pasture/stable, bedding, dust exposure)
2. General health maintenance (deworming, vaccinations, hoof trim, dentals)

Question 17

Prognosis for ERU?

Answer 17

-Long-term prognosis for vision generally poor (50-60% lose vision)
- Blindness due to secondary cataract, glaucoma, or retinal detachment common

Question 18

What is the most common cause of uveal cysts?

Answer 18

Idiopathic cystic corpora nigra

Question 19

How can we distinguish uveal cysts from melanoma?

Answer 19

Cysts will transilluminate

Question 20

Etiology of chorioretinitis:

Answer 20

1. ERU
2. EHV
3. Trauma

Question 21

“Bullet hole” chorioretinopathy is often an incidental finding but can be caused due to what infectious agent?

Answer 21

EHV-1 & EHV-5

Question 22

What are the congenital causes of equine vision loss?

Answer 22

1. Cataracts
2. Optic nerve coloboma
3. Congenital stationary night blindness

Question 23

What is CSNB?

Answer 23

Normal daytime vision
Blind in dark/dim lighting
Normal retina (ERG required for diagnosis)
Appaloosa’s most commonly affected (heritable)

Question 24

What are some acquired causes of equine vision loss?

Answer 24

1. ERU
2. Glaucoma
3. Traumatic optic neuropathy
4. Exudative optic neuropathy

Question 25

What is the cause and etiology of traumatic optic neuropathy?

Answer 25

Causes: trauma, especially striking the poll Etiology: shearing of the optic nerve/chiasm **ACUTE, IRREVERSIBLE BLINDNESS**