Equine ophthalmic disease and treatment

Question 1

typical presentation of ulcerative keratitis (corneal ulceration)

Answer 1

usually painful
corneal opacity
secondary uveitis typically present

Question 2

List 4 things seen with secondary uveitis

Answer 2

myosis
empyema/ hyphema/ synaechiae
iris prolapse
fibrin in anterior chamber

Question 3

diagnosis of ulcerative keratitis

Answer 3

Fluorescein Stain- Observe with blue light

Question 4

Management of ulcerative keratitis

Answer 4

does it need debriding
pain management
antimicrobials

NEVER steroids with corneal ulcers

Question 5

why do we do grid/ puncture keratotomy over an ulcerated eye

Answer 5

Exposes stromal collagen
Promotes epithelial stronger attachment
Takes longer (1-3 weeks) but more likely to heal

Question 6

List 2 forms of antimicrobial treatment of corneal ulcers

Answer 6

Ointments= more suitable for owner’s administration (3-4 times daily)
Drops= best in hospital settings (from 12 to 4 times daily)

Question 7

Pain management of corneal ulcers

Answer 7

flunixin meglumine IV - most efficacious
paracetamol
opiods?
topical anti-inflammatories

Question 8

how to control myosis in corneal ulcers

Answer 8

Topical atropine until mydriasis then as required to maintain
also need- dark environment and mask

Question 9

List 2 ways to prevent Collagenolysis in corneal ulcers

Answer 9

autologous serum
EDTA plasma

require frequent administration so only suitable for hospital setting

Question 10

Describe sub-palpebral lavage devices in horses with corneal ulcers

Answer 10

they allow you to lavage the eye without having to open it or get in the horses face

Question 11

Describe the 2 types of presentation of viral keraitis

Answer 11

Type I – Dendritic pattern
Type II – Multifocal pattern- more common

Question 12

Describe how to treat viral keratitis

Answer 12

Idoxuridine for 7 days
Can try other anti-virals= e.g. Acyclovir (II), trifluridine (I, II), vidarabine

Question 13

Treatment of fungal keratitis

Answer 13

azole antifungals
Subconjunctival Amphotericin B
Prophylactic antimicrobials
EDTA, serum, tetracyclines

Question 14

when should we refer a corneal ulcer

Answer 14

Positive Seidel test (evidence of perforation), iris prolapse
Severe uveitis
Melting
Requires debridement and you are not happy to debride
Deteriorates despite treatment
Horse difficult to medicate

Question 15

when should you consider enucleation in cases of corneal ulcers

Answer 15

if eye is non-visual

Question 16

How to treat immuno-mediated keratitis

Answer 16

Dexamethasone
Calcineurin inhibitors (Cyclosporin A and Tacrolimus)
Doxyciclyne

Question 17

Main thing to do when looking at corneal disease in horses

Answer 17

use stain
if +ve more likely corneal disease- so then do that treatment
if -ve more likely immune mediated- steroids to treat

Question 18

How to treat eye neoplasia

Answer 18

Mytomycin C- Daily for a week every other week for 4 treatments
Cryotherapy
surgical debridement
enucleation is always an option

Question 19

what is the uvea

Answer 19

Iris
Ciliary body
Choroid – blood supply to retina

Question 20

when does equine uveitis occur

Answer 20

secondary (trauma, ulceration, any ocular disease)
primary (immunomediated, equine recurrent uveitits)

Question 21

what can equine uveitis lead to

Answer 21

Synechiae
Iris rests
Change in iris pigmentation
Reduction in size of corpora nigra
Cataracts
Retinal detachment
Glaucoma
BLINDNESS

Question 22

Difference between equine uveitis and equine recurrent uveitis

Answer 22

First time? –>Uveitis
More than once –> suspect ERU

Question 23

what horse breed is predisposed to equine recurrent uveitis

Answer 23

Appaloosas

Question 24

How to treat equine recurrent uveitis

Answer 24

topical steroids (immune-mediated disorder)
atropine
+/- cyclosporin A
Supra-choroiodal cyclosporine implant- long term managament

Question 25

what can really help treat equine recurrent uveitis - decribe

Answer 25

Supra-choroiodal cyclosporine implant
needs to be done during remission and cause >5 years remission
can be repeated

Question 26

How to treat iris cyst

Answer 26

Benign neglect
Can aspirate if a problem- they can rupture
Laser

Question 27

what signs can iris cyst cause

Answer 27

Can obstruct vision
Head-shaking
Can rupture

Question 28

Describe habronemiasis - and treatment

Answer 28

granulomatous lesions from flies
ivermectin, systemic NSAIDs and fly control

Question 29

How to debride corneal ulcers

Answer 29

using a cotton bud, needle, scalpel or bur

Question 30

why serum eye drops useful for ulcers in horses

Answer 30

the serum has anti-collagenase activity, antibodies within the serum to help fight the infection, nutrients, growth factors and vitamins are present

Question 31

why is EDTA given in the serum eye drops for corneal ulcers

Answer 31

EDTA helps slow the breakdown of the stroma and give the antibiotics time to clear the infection

Question 32

what causes viral keratitis

Answer 32

EHV-1,2 and 4
(EHV-2 is the main cause)

Question 33

Describe how stromal abcesses can occur

Answer 33

if debridement of a corneal ulcer is unsuccssful, the ulcers top layer can heal but leave an abscess in the stroma - this will eventually heal but may take longer

Question 34

common types of neoplasia in the eye

Answer 34

squamous cell carcinoma
melanomas