Equine Opthalmology

Question 1

What is entropium?

How would you treat it?

Answer 1

Eyelids rolled in
-foals

Tx: Drop with xylazine and Ketamine, no heavy sedation
Mild form in foal
-Saline bleb
-Percutaneous sutures:
1) simple interrupted sutures (inverting pattern)
2) mattress sutures (everting)
Severe form: 
-Sx remove skin

Question 2

What is ectropium?

Answer 2

Eyelid rolls out

Question 3

Why do you not want to cut skin with scissors?

Answer 3

They have a crushing action, not good for wound margins

Question 4

What is eye lid coloboma?

Answer 4

Coloboma = gash, defect, cut

• Acquired
• congenital

Question 5

What crude method can you use to check if the cornea is intact?

Answer 5

Take a picture, if fussy cornea has blemish

Question 6

How do you treat an eyelid laceration?

Answer 6

Eye lid suturing

-need close margins

Question 7

What is very important in eye lid suturing?

Answer 7

Need to be very precise and margins close together

• suture conjunctiva first
• want knot away from eye lid margin

Question 8

What surgical technique is used, when a large portion of the eye lid needs to be incised. Ie: Squamouse cell carcinoma in cow eyelid?

Answer 8

Slide flap technique

• Borow’s triangles
• slide flap up
• simple interrupted

Question 9

What is the outer most layer of the cornea

Answer 9

Tear film

-macrophages (control infection and the environment there)

Question 10

What are the different layers of the cornea?

Answer 10

Outermost to inner most:
Tear film
Corneal epithelium
Corneal stroma
Descemet’s membrane
Endothelium

Question 11

What is unique to healthy cornea?

Answer 11

Not vascularised

Question 12

What is the thickest layer of the cornea?

Answer 12

Corneal stroma

• non pigmented
• collagen fibers (arranged in parallel fashion)

Question 13

How are the collagen fibers in the corneal stroma arranged?

Answer 13

Parallel fashion

Question 14

What is the most inner layer of the cornea?

Answer 14

Endothelium

-one cell layer thick

Question 15

Would you see the tear film of the cornea under microscopic view?

Answer 15

No fixation removes it

Question 16

What are the clinical signs of Keratitis?

Answer 16

1) blepharospasm (blepharo =eyelid, Squinting)
2) Epiphora (tearing)
3) Corneal edema (increased fluid in the stroma)
4) cornea opacity

Question 17

What is keratitis?

Answer 17

Inflammation of the cornea

Question 18

What is blepharospasm?

Answer 18

Squinting

Question 19

Where do you normally see epiphora?

Answer 19

At the medial canthus of the eye

Question 20

How can you be absolutely sure the tear film of the cornea is intact?

Answer 20

FLuorescein test

Question 21

When you do a fluroscene stain, what is stained?

Answer 21

The stroma

Question 22

What is cornea vascularization?

Answer 22

Eye healing itself, bringing in blood vessels

-can be seen with keratitis

Question 23

Superficial vascularisation

Answer 23

Heavily branched vascularisation pattern

-common with superficial cornea ulcer

Question 24

Deep vascularization

Answer 24

Single branched, Long corneal vessels

-deep corneal ulcer

Question 25

How do you apply eye medication in a horse?

Answer 25

• heavy sedation, local block

- upper fornix of the eye

Question 26

What are some reason a horse might not respond to eye medication?

Answer 26

Corneal ulcer edge:

• infection underneath the epithelium
• antibiotics not working

Or

Corneal fungal infection
-need to identify and culture

Question 27

When do you use a conjunctival pedicure flap

Answer 27

Gives additional blood supply

• attached to the cornea
• needs to be removed months later

Question 28

T/F: Stromal infections always stain with fluorescent

Answer 28

False

Stromal infections do not always stain with fluorescence

Question 29

What is the correct suture placement for a corneal laceration?

Answer 29

• Suture should not penetrate to the inside
• place knot to the side
• cornea must be appositional
• sutures must be exactly opposite

Question 30

What is a staphyloma, and what does it usually occure from?

How is it treated?

Answer 30

Staphyloma = iris protruding through laceration of cornea

• Occurs from corneal laceration
• looks like a dark portion protruding from the eye

Tx: push Irish back during surgery, place corneal suture

Question 31

What is endophthalmitis?

Answer 31

Inflammation of the eye + straining of the eye

Question 32

What is exenteration?

Answer 32

Complete removal of the eye