Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Year 4 Small Animal Studies > Ophthalmology: Cornea > Flashcards

Ophthalmology: Cornea Flashcards

1
Q

Describe the anatomy of canine conjunctiva?

A
  • Thin mucous membrnae
  • Lines the lids reflected at the dorsal and ventral fornices onto the globe
  • Covers nicitating membrane
  • Contains globles cells- mucus fraction of tear
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q
  1. What is the normal colour of mucus from the conjunctiva?
  2. What colour does it change to with conjunctivitis?
A
  1. Off-white, darkens to grey with air
  2. Yellow/green
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q
  1. What are primary causes of non-specific conjunctivitis?
  2. How is it usually treated?
A
  1. Wind, dust, trauma- oppertrunistic
  2. Fusidic acid- effective against staphs or broad spec AB (gentamycin)

If persist look for another factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What produces the tear film in the dog?

A

Three layers
* Mucus- globlet cells of the conjunctiva
* Aqueous- lacrimal gland/nicitating membrane
* Lipid- tarsal glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q
  1. What is KCS or Dry eye?
  2. What are the clinical signs?
A
  1. Keratoconjunctivitis sicca- deficiency of aqueous tear film production
  2. Clinical signs
    * Loss of corneal reflex
    * Corneal ulceration- acute
    * Superficial keratisis
    * Corneal pigmentation
    * Diffuse conjunctivitis
    * Mucopurulent occular discharge

Most are chronic and progressive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What breeds are represented for KCS?

What can cause it?

A
  • WHWT
  • Cocker
  • Brachycephalics
  • Bulldogs

Upper lid trichiasis, congenital, neurogenic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is KCS diagnosed?
How is it medically managed?

A

Diagnosis
* Schirmer tear test strips
* Measure flow over 1min
* 15mm minimum

Medical managment
* Tear stimulants- cyclosporin or tarcolimus
* Lubricants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
  1. What is dry eye-dry node syndrome?
  2. How is it treated?
A
  1. One eye and ipsilateral nasal planum suffer loss of gland function- neurogenic
  2. Pilocarpine eye drops in food
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How do tears drain?

A

Naso-lacrimal duct- near the medial canthus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How are tear drainage problems investigated and diagnosed in dogs?

A
  • Rule out painful causes of lacrimation
  • Examine medial canthus for entropion
  • Establish normal nasolacrimal puncta
  • Instil 1 drop of fluorescein into both eyes
  • Flush with saline and wait
  • 3-4 mins should flow into nares
  • Flush system- sedate, lacrimal cannula

Brachys negative- weird

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are common causes and treatments of tear drainage problems?

A

Congenital micropuncta
* Golden retriever, cocker spaniel
* Thin membrane- excised

Dacryocysitis- infection/inflammation of duct from FB

Epiphora- permanent opstruction- bypass surgery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the 4 layers of the cornea?

What innervates the cornea?

A
  1. Outer epithelium- needs tears
  2. Stroma- consisting of fine collagen fibrils arranged in lamellae- precise arrangment
  3. Descemets membrane- acellular basemend membrane
  4. Endothelium- monolayer of flat cells

Opthalmic branch of trigeminal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is required for the normal cornea to be transparent?

A
  • No keratin
  • No pigment
  • Avascular
  • Precise arrangment of collagen in stoma- no oedema, scar tissue, inflammatory tissue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is a corneal ulcer?

A

A full thickness defect in the epithelium of the cornea- outermost layer

Very painful- potential for deeper progression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How is corneal ulcer diagnosed?

A
  • Corneal contour is disrupted often with surrounding oedema
  • Fluorescein- washes of intact, stains exposed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What could a ‘clear non-staining area in the centre of a ring’ mean with a fluorescein stain

A
  • The descemets membrane does not stain
  • Therefore could indicate a serious deep ulcer
  • Check for perforation- space between iris and cornea
17
Q

What can be a primary cause of corneal ulcers?

A

Factors causing mechanical damage
* Trauma, entropion, FB etc

Factors contributing to unhealthy superficial corneal environments
* KCS
* neurogenic

Inherent corneal defects
* Indolent ulcers
* Chronic oedems

Pugs are just high risk for ulcers, both getting and deterioration

18
Q

What should non-specific medical support consist of?

A
  • Broad spec, topical ABs
  • Lubricant?
  • Atropine- relieves pupil spasm
  • Serum or other anti-collagenases
19
Q

Why are topical steroids contraindicated for corneal ulcers?

Why are local anaesthetic drips contraindicated for corneal ulcers?

A

Steroids
* Inhibit epithelial healing
* Predispose to infection
* Potentiate the action of collagenases, causing melting

LA
* Only lasts 1hr
* toxic to epithelium
* Prevents blinking

20
Q

Why is surgical treatment of ulcers controversial?

A

Now controversial: third eyelid flap
* Obscures the eye
* Interferes with medication
* Not adequate for deep ulcers or indolent

Surgery is required for deep ulcers with no vascular ingrowth

21
Q
  1. What breeds more commonly ave indolent ulcers?
  2. How does it appear?
  3. How is it treated?
A
  1. Boxer, staffie, corgi
  2. Very shallow ulcer with only the epithelium lost and underruning of the epithelium
  3. Medical/third eyelid flap ineffective- must be debrided
    LA, cotton wool around the tip of an artery forceps- scalpel blade in scraping action
22
Q

What are the non-ulcerative corneal conditions?

A
  • Pigmentary keratitis
  • Senile corneal endothelial dystrophy
  • Lipid depositions
  • Dermoid
  • Pannus
  • Lacerations/penetrations
23
Q

What casues pigmentary keratitis?

A

Pigment is carried from the limbus along with new blood vessels in reponse to superficial damage
* Not primary
* Does not regress

24
Q

What causes senile corneal enothelial dystrophy?

A

Progressive degeneration of the endothelium leads to chronic corneal oedema

Can rupture leaving ulcers

25
Q

Where are the two most common lipid depositions of the cornea?

A

Paracentral lipid dystrophy
* Sub-epithelially in the anterior third of the cornea
* No pain, vascularisation, no systemic problem
* Tx- superficial keratectomy- not necessary

Lipid keratopathy
* Deposition of lipids in association with inflammation and vascularisation
* Usually secondary to previous injury or ulceration

26
Q

What is corneal dermoid?

A
  • A patch of well differentiated skin present congenitally on the cornea usually at the lateral limbus

Tx- superficial keratectomy

27
Q

What is pannus?

A
  • A chronic superficial vascular keratitis- GSD
  • A front of pigment, inflammatory tissue and vessels advances across the cornea
  • Infiltration is sub-epithelial and therefore fluorescein negative

Tx- topical steroids or cyclosporin

Year 4 Small Animal Studies (97 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions