Brainscape's Knowledge GenomeTM

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


See full index

NOSS > The Opaque Eye > Flashcards

The Opaque Eye Flashcards

1
Q

What are the three cell types of the corneal epithelium?

A

Basal cells, wing cells and squamous non-keratinised epithelium

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

What is the function of the basal cells?

A

Transient amplifying cells capable of mitosis with stem cells at the limbus

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

What is the function of the wing cells?

A

No longer mitotic and make up the second section of the epithelium with between 2 and 4 layers of cells

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

What is the function of the squamous non-keratinised epithelium?

A

Top section and is sloughed off with blinking

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

What are the methods of corneal epithelial healing?

A

Sliding movement
Vertical movement
Centripetal movement

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

When does sliding healing occur?

A

Minor damage to the top layer of the epithelium

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

How long does healing by sliding take?

A

24 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When does vertical movement occur?

A

After sliding movement and involves basal cell mitosis and deals with daily loss of cells/regaining thickness of epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How long does vertical healing take?

A

1-2 weeks

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

What is the process of centripetal healing?

A

Path the epithelial cells take from the edge of the cornea at the limbus to the centre in the shape of a spiral

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

When is centripetal healing clinically significant?

A

If healing results in concurrent pigment production as this could obscure vision if it reaches the centre of the eye and covers the pupil

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

What is healing by sliding dependent on?

A

Corneal health, existence of limbal basal cells and basal lamina, species and age of the animal

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

What happens if there are no limbal stem cells?

A

Conjunctiva can provide the epithelium but this is opaque and can lead to symblepharon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why does vascularisation occur in corneal epithelial healing?

A

Angiogenic factors are not well understood but inflammation is thought to be a stimulus

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

What process does vasculatisation occur by?

A

Inflammation stimulates and the vessels can coalesce to form granulation tissue and the vessels atrophy once the stimulus is removed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the two different types of blood vessels that form? How do you differentiate them?

A 
Superficial = dichotomous
Deep = straight and look painted on
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why is vascularisation important to corneal healing?

A

Blood vessels bring stabilising serum to protect against corneal melting, nutrients, growth factors and inflammatory cells as well as structural support for reconstruction/remodelling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do vessels indicate chronicity?

A

Vessels take 2-4 days to bud and grow at 1mm/2days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What makes up the stroma?

A

Collagen lamellae made up of predominantly collagen I fibrils and keratocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the arrangement of the collagen fibres of the stroma?

A

Travel from limbus to limbus and are united and ordered by GAGs and kept relatively dehydrated so they are transparent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What chemokines are involved in stromal healing?

A

IL-1, EDGF, TNF-beta, collagenases and metaloproterases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What produces the chemokines?

A

The lacrimal gland as well as epithelial cells, stromal keratocytes, corneal nerves and leukocytes attracted to the wound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the role of monocytes, macrophages, neutrophils and T cells?

A

Destruction and clean up of damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How does the initial scar form?

A

Keratocyte-mediated build up of collagen fibrils and their interconnections as well as ECM GAGs but these aren’t in the correct quantities/types/distribution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What can cause an imbalance in destruction and build up?

A

Tear film imbalance, iatrogenic causes, entropion, distichiasis, trichiasis etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How long does stromal healing take?

A

Weeks for stroma to fill defect and months of remodelling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the structure of the endothelium?

A

Chicken wire pattern

28
Q

What is the function of the endothelium?

A

It keeps stroma dehydrated by being a physical barrier and sodium - potassium pumps which put fluid back in the anterior chamber

29
Q

What is a special feature of the endothelium?

A

Cells become larger when their neighbours die resulting in pleo/polymorphism with more sodium-potassium pumps

30
Q

What happens if endothelial repair fails?

A

Corneal oedema

31
Q

What can damage the endothelium?

A

Glaucoma, uveitis, anterior lens luxation, direct damage intra-operatively or by chemical damage as well as Primary Endothelial Degeneration

32
Q

What is the difference between superficial and deep ulcers?

A

Superficial stain with fluorescin and look like a small scratch or graze
Deep don’t stain as stroma is gone and have a clear dark centre

33
Q

What is collagenolysis?

A

Corneal melting

Can progress rapidly within hours or a handful of days and can result in perforation of the cornea

34
Q

What is the treatment for superficial ulcers?

A

Allow time to heal themselves, check every 3-5 days, if not healing consider where the healing imbalance is occuring

35
Q

What are the common problems with healing?

A

Tear film abnormalities (quantitative/qualitative), eyelid problems, third eyelid problems, brachycephalic effect, secondary infection or corneal melting

36
Q

What are the key signs of no healing?

A

Lack of re-epithelialisation, stromal wound deepening and stroma devitalising

37
Q

What are the diagnostic steps to follow if an ulcer isn’t healing?

A

STT-1 and an eyelid exam

38
Q

What forms of protection are there for ulcers?

A

Elizabethan/buster collar
Tarsorrhaphy
TE/nicitating membrane flap

39
Q

What is a tarsorrhaphy?

A

Horizontal mattress suture through eyelids using stents to protect eyelids. 1st exit suture and 2 entrance suture through meibomian gland to ensure you get tarsal plate

40
Q

What antibiotics can be used to treat ulcers?

A

Fusidic acid gel, BID, mostly vs gram +ves

Chloramphenicol eyedrops, TID, good penetration, gram +ves

41
Q

What other treatments can be used?

A

Serum eyedrops to prevent melting every 30 mins once started or TID to prevent melting occuring
Atropine to relax ciliary body and iris causing mydriasis, BID for 1-2 days
Preservative free viscous tears

42
Q

What is the treatment for a descemetocoele?

A

Surgical repair

43
Q

What is KCS and what causes it?

A

Keratoconjunctivitis Sicca

Primary or secondary to evaporation, drugs, anaesthetics and sedatives or neurogenic

44
Q

What is Trend A of Primary Keratoconjunctivitis Sicca (KCS)?

A

0-2 years/6-8 years
More males than females
Non sterilised
Ulcerative keratitis in 50-72% with many rapidly perforating

45
Q

What is Trend B of Primary Keratoconjunctivitis Sicca (KCS)?

A

5 years
More females than males
Lower incidence of ulcerative keratitis (4-22%) with most superficial

46
Q

Why do central/paracentral ulcers perforate?

A

Diseased cornea, irritant still present, abnormal clearing due to increased thick mucoid discharge, change in bacterial flora or inflammatory cells in surface

47
Q

What are the early surgical and medical treatments?

A

CLCT, conjunctival pedicle graft, topical ciclosporin, preservative free viscous tears, topical antibiotics, serum eyedrops

48
Q

What is CLCT?

A

Corneolimboconjunctival transposition and uses a clear peripheral cornea leaving a clearer visual axis after healing than other techniques

49
Q

When would you use a conjunctival pedicle graft and why?

A

For peripheral ulcers as its quicker although it doesn’t clear much over time but its not that important as its peripheral

50
Q

What does SCCEDs stand for?

A

Spontaneous Chronic Corneal Epithelial Defects

51
Q

What are the clinical signs of SCCED?

A

Loose epithelial edges, under-running of fluorescein dye, positive pulsed saline test
+/- corneal oedema, +/- ocular pain, +/- ulcerative damage

52
Q

What are the causes of SCCED?

A

History of minor trauma, anterior stroma, PAS+ (staining technique), acellular zone with hyaline membrane, hyaline membrane interferes with epithelial adherence to the stroma

53
Q

What is the surgical treatment for SCCED?

A

100% success with keratectomy and best outcome in cats

54
Q

What treatments are contraindicated in cats?

A

Debridement and grid keratotome/superficial scrape

55
Q

What is the medical treatment for SCCED?

A

Chloramphenicol TID +/- serum eye drops TID/QID

56
Q

What is Feline Corneal Sequestrum?

A

Spontaneous, uni/bilateral, tan to black discolouration of superficial stroma, localisation varies with cause

57
Q

What is the progression of Feline Corneal Sequestrum?

A

Darker plaque to neovascularisation to ulceration around the plaque

58
Q

What are the theorised aetiologies?

A

Corneal trauma, tear film stability and goblet cell function, lower corneal sensitivity, lipid abnormalities and possible dessication or FHV-1

59
Q

What is the treatment?

A

Superficial keratectomy +/- bandage lens +/- tarsorshaphy

Superficial keratectomy and grafting

60
Q

How does FHV-1 infection occur?

A

Cats infected in kittenhood and virus lives in trigeminal ganglion and corneal tissue

61
Q

What does FHV-1 cause?

A

Severe corneal ulcerative disease that recrudesces in times of stress, early ulcer is dendritic (pathognomonic) and progesses to more common geographical ulcer

62
Q

What is the treatment for FHV-1?

A

Interferon and L-lysine
Antiviral eyedrops 4-6 x daily but very irritant
(systemic antivirals)

63
Q

What is feline acute bullous keratopathy?

A

Unknown aetiology

Acute development of corneal oedema where cornea becomes soft and at risk of melting and perforation

64
Q

What does facial nerve paralysis cause?

A

Loss of blink leading to interpalpebral fissure ulceration

65
Q

How is facial nerve paralysis treated?

A

Tarsorrhaphy for 1-2 months as well as protective collar, topical antibiotic and preservative free viscous tears

NOSS (27 decks)

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