Exam 3 Optho

Question 1

the 4 layers of the cornea are:

Answer 1

squamous epithelium, stroma, descemet’s membrane, and endothelium

Question 2

T/F: the stroma composes 90% of the corneal thickenss

Answer 2

true

Question 3

the cornea functions as a _____________ and is a refractive structure of the eye, focusing light onto the ______________.

Answer 3

protective barrier; retina

Question 4

how does the corneal epithelium contribute to keeping the cornea in a relative state of dehydration?

Answer 4

it pumps fluid. from the cornea into the anterior chamber.

Question 5

T/F: Defects in the corneal epithelium result in focal corneal edema.

Answer 5

true. because the epithelium normally prevents fluid from entering the cornea via the tear film.

Question 6

edema can occur from what two general conditions?

Answer 6

epithelial defects (allowing the fluid from the tear film to leak into the cornea) or corneal endothelial dysfunction (due to decreased pump functions)

Question 7

T/F: the corneal endothelium can regenerate in an adult animal.

Answer 7

False. Extensive loss or degeneration of corneal endothelium results in permanent corneal edema.

Question 8

Corneal vascularization may occur in response to what diseases?

Answer 8

corneal, scleral, or intraocular

Question 9

Describe how defects in the corneal epithelium heal (corneal ulcers).

Answer 9

Corneal ulcers heal from adjacent epithelium sliding over the area and then undergoing mitosis to eliminate the defect.

Question 10

How are corneal stromal defect healing mechanisms similar or different to corneal epithelial defect healing mechanisms?

Answer 10

Stromal defect healing, similar to epithelial, are also covered by sliding and mitosis of adjacent epithelium.

It’s different because fibroblasts (from keratocytes) begin to proliferate and lay down new collagen, though it’s irregularly arranged, forming visible corneal scars)

Question 11

describe corneal. vascularization

Answer 11

this is where blood vessels grow in from the limbus towards the site of corneal defect.

Question 12

T/F: Blood vessels in response to surface corneal disease (i.e. ulcer) are typically superficial and are typically straighter.

Answer 12

False. Though the blood vessels are typically superficial in response to surface corneal disease, they undergo branching

Question 13

Deeper in the cornea, appear much straighter and enter the cornea circumferentially.

This type of corneal vascularization is associated with what type of disease?

Answer 13

intraocular disease

Question 14

occurs in response to chronic corneal inflammation or irritation.

Answer 14

corneal pigmentation

Question 15

How is corneal pigmentation associated with corneal vascularization?

Answer 15

Melanocytes, in response to chronic corneal inflammation or irritation, enter the cornea from the limbus in association with corneal neovascularization

Question 16

What companion animal species and breed do you most commonly see corneal pigmentation?

Answer 16

Dogs; brachycephalic

Question 17

Congenital Corneal Disorders include:

Answer 17

Dermoid and Persistent Pupillary Membranes (PPMs)

Question 18

The most common congenital corneal abnormality is the

Answer 18

Dermoid

Question 19

Where does the dermoid come from?

Answer 19

It arises at the lateral limbal conjunctiva and extends on to the cornea

Question 21

Uveitis is

Answer 21

Inflammation inside the eye. Can be caused by multiple things. Secondary effect from an ulcer.

Question 22

Complications of a corneal ulcer include:

Answer 22

Secondary infection
Stromal collagenolysis
Uveitis
Corneal perforation

Question 23

T/F: Horses get really bad uveitis ulcers

Answer 23

True

Question 24

The Descriptive classification of corneal ulcers are:

Answer 24

Superficial, Stromal (mid or deep) and Descemetocele (worst ulcer you can have)

Question 25

Ulcers can typically heal with medical at what layer of the cornea? What layer do they typically not heal with medical management?

Answer 25

Acute superficial, mid/ deep Stromal

Typically need surgical management at descemetocele and corneal perforation

Question 26

Clear signs of bacterial infection are

Answer 26

Deep ulcers and purulent discharge within the ulcer

Question 27

List the goals of therapy for corneal ulceration.

Answer 27

Prevent/ control infection and collagenolysis, increase patient comfort, and promote healing

Question 28

In what species does fungal keratitis occur most often?

Answer 28

Horses

Question 29

In which species do you always use cycloplegic agents? Why?

Answer 29

Horses because they have bad reflex uveitis, which causes a lot of pain when they have an ulcer.

Question 30

Define cycloplegic

Answer 30

Relaxing smooth muscle of the eye

Question 31

T/F: It it suggested to use corticosteroids in the presence of corneal ulcers.

Answer 31

False! Topical corticosteroids are contraindicated in the presence of corneal ulcers

Question 32

List surgical therapies of corneal ulcers and their functions.

Answer 32

Keratectomy: removes necrotic/ infected tissue
Corneal or biomaterial graft: provides structural support
Conjunctival flap/ graft: speeds healing of cornea

Question 33

Describe the benefits of conjunctival flaps

Answer 33

Provides mechanical support, immediate blood supply, a source of fibroblasts and epithelial cells

Question 34

What is SCCED? Describe the clinical appearance of it.

Answer 34

SCCED= spontaneous chronic corneal epithelial defect

It is a superficial, non-healing ulcer where it heals, but the corneal epithelium and corneal scleral tissue don’t attach.

Question 35

Describe the treatment plan for a patient with a SCCED ulcer. What is another name for this type of ulcer?

Answer 35

Using a cotton swab, remove the top layer of epithelium (corneal debridement), then perform keratotomy/ keratectomy and remove damaged tissue by making a grid pattern or by using a diamond burr to abraid the surface. Lastly, manage as a superficial ulcer until healed.

Another name for SCCED is boxer ulcer

Question 36

Treatment of FHV-1 Keratitis includes

Answer 36

Topical antibiotics
Antivirals (topical/ oral)
Anti-inflammatories (NSAIDS)

Question 37

Would you use steroids on a cat presenting with FHV-1 Keratitis?

Answer 37

NO! Do not use a steroid in an ulcer!! It can cause other problems such as another ulcer induced by the steroid.

Question 38

Concerning canine herpesvirus, when do you most commonly see ulcers appear?

Answer 38

In immunosuppressed dogs

Question 39

What is the etiology of infectious bovine keratoconjunctivitis?

Answer 39

Moraxella bovis