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Module 6 Cornea Sclera And Episclera > Cornea > Flashcards

Cornea Flashcards

1
Q

What does the epithelium originate from (embryology)?

A

Surface ectoderm

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2
Q

Where does the cornea get its nutrition from?

A

Aqueous humour

Limbal blood vessels

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3
Q

Where does the cornea get its oxygen from?

A

Tear film

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4
Q

What does the corneal endothelium and stroma originate from?

A

Mesenchymal neural crest cells

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5
Q

What are the 3 layers of the tear film and where do they come from?

A

Lipid- meibomian gland (decreases evaporation)
Aqueous- lacrimal gland
Mucin- conjunctival goblet cells (spread)

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6
Q

How many layers is the epithelium? (X-x)

A

5-7 layers

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7
Q

What cells form the basal layer of the epithelium?
What is it adhered to?
What cells join the basal cells together?

A

columnar cells

adhered to the basement membrane

Desmosomes, hemidesmosomes, gap junctions

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8
Q

What cells form the intermediate layer of the epithelium?

What are these cells attached to each other by and to superficial cells?

A

Interdigitating wing cells
2-3 layers

Desmosomes and gap junctions

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9
Q

What cells make up the top layer of the epithelium?
What joins the cells?
What is on top of these cells?

A

Flattened squames
3-4 layers

Desmosomes and tight junctions

Microvilli and microplicae

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10
Q

What % of the cornea does the stroma account for?

A

90%

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11
Q

What is the main component of stroma?

A

Collagen

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12
Q

What cell allows maintenance of the stroma?

What enzyme does it produce?

A

Keratocytes

Proteases

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13
Q

What is the basement membrane of the stroma called?

Where is it secreted from?

A

Descemet’s membrane

Corneal endothelium

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14
Q

How many layers thick is the endothelium?

A

Single layer

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15
Q

When an epithelial defect occurs what does the epithelium do?

A

Cells flatten, spread and move across the defect

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16
Q

Where do superficial corneal blood vessels come from (thin wiggly - trees)?

A

Conjunctiva

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17
Q

Where do deep corneal blood vessels come from (straight short hedges)?

A

Limbus

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18
Q

What breeds are most affected by pannus/chronic superficial keratitis?
What age?

A

GSD
Collie
Greyhound
Lurcher

3-5yo

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19
Q

What are the clinical signs of pannus/chronic superficial keratitis?
Which areas are affected?
Uni/bilateral?

A

Red eyes
Vascularisation, infiltration, pigmentation starting at the Ventrolateral limbus

Cornea, conjunctiva, third eyelid affected

Bilateral

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20
Q

Ulceration is common or rare in pannus/chronic superficial keratitis?

A

Rare

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21
Q

How do you diagnose pannus/chronic superficial keratitis?
What is the main result?
What is the treatment for pannus/chronic superficial keratitis?

A

Biopsy

Plasma cells

Topical steroids/ciclosporin or both together
Often need repeat courses

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22
Q

What time of year is pannus worst? Why?

A

Summer - triggered by UV light

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23
Q

What condition is this likely to be in a cat?
What are the clinical signs? Where?
What age?

A

Eosinophilic keratoconjunctivitis

White and pink deposits (cottage cheese!)
Superficial corneal stroma and epithelium, conjunctiva
Young/ Middle Aged

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24
Q

How do you diagnose eosinophilic keratoconjunctivitis?
What’s the result?
Treatment?

A

Cytology (scrapings/biopsy)

Mast cells and eosinophils (with some mixed inflam cells)

Topical steroids/ ciclosporin
(Oral preds If topical not poss)

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25
Q

What are the clinical signs of superficial punctate keratitis?

Which breeds are predisposed?

A

Multiple fluoro positive corneal opacities (white)

Shetland sheepdogs
Min LH daschunds

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26
Q

What is this likely to be (dog)? Single/multiple raised lesion dorsolateral limbus

What is the treatment?

A

Nodular granulomatous episcleritis

Topical +/- immunosuppression

27
Q

Limbal/ epibulbar melanoma are common in what type of dogs?

Treatment?

A

Darkly pigmented dogs;
Labs
GSD

Excise +/- adjunctive therapy

28
Q

What could be the cause of corneal lipidosis?

A 
Just inherited 
Primary hyperlipidaemia
DM
HyperA
Hypothyroidism
29
Q

Does corneal lipidosis cause inflammation?
Bilateral/ uni?
Location?

A

No
Bilateral
Subepithelial, central/para central

30
Q

How is Lipid keratopathy different to lipid dystrophy?

Treatment?

A

Lipid keratopathy has inflammation and blood vessels

Treat cause of hyperlipidaemia, can do keratectomy/ laser but do this after plasma lipidaemia stable!

31
Q

Which causes with which?

Larger lipoproteins (triglyceride rich)
Smaller lipoproteins (cholesterol rich)
Causes… 
Lipid keratopathy 
Arcus lipoides corneae
A

Larger lipoproteins (triglyceride rich) cause Arcus lipoides corneae

Smaller lipoproteins (cholesterol rich) Causes Lipid keratopathy

32
Q

PDT can cause what type of corneal opacity?

A

Calcification

33
Q

What is the breed predilection for dermoids?

A

GSD

St Bernard’s

34
Q

What is the purpose of thermal keratopasty in endothelial dystrophy?
How does it do this?

A

Preventing corneal ulceration.

Post operative fibrosis of the corneal stroma squeezes fluid out and prevents further fluid entry.

35
Q

Which breed of cat is stromal dystrophy found in?

Uni/ bilateral?

A

Manx cat

Bilateral

36
Q

Which breed is macular corneal dystrophy seen in?
What age?
What are the clinical signs?
What test can be done?

Cause?

A

Lab
Middle aged (~5yo)
Stromal opacity +/- vascularisation
DNA - carbohydrate sulfotransferase 6

Accumulation of glycosaminoglycan

37
Q

What is the treatment for epithelial inclusion cyst?

A

Surgical excision

38
Q

What is the treatment for stromal keratitis in cats with FHV?

A

Antivirals + steroids

39
Q

What appearance on the cornea does mycotic keratitis have?

A

White (icing sugar) appearance

40
Q

Within what time should an uncomplicated ulcer heal?

A

7days

41
Q

How long should you use a diamond burr on a SCCED for?

A

45-60secs

42
Q

What enzymes cause the stroma digested causing a melting ulcer?
What are these enzymes produced by?

A

Proteases and collagenases

Pathogenic organisms, inflammatory cells, resident corneal cells

43
Q

What is the purpose of corneal cross linking?

A

Stabilise and sterilise the cornea

44
Q

Describe these 3 layers of the epithelium?

A

Top- squamous cells
Middle - intermediate wing cells
Bottom- Columnar cells (regenerating)

45
Q

What is this?

What part of the eye has to be defected for this to occur?

A

Corneal hydrops

Descemets membrane

46
Q

What cells have to be damaged for oedema to enter cornea?

A

Epithelial cells

Endothelial cells

47
Q

What are white/tan precipitates In the eye?

What do they indicate?

Where do they stick to?

A

Keratic precipitates

Uveitis

Endothelium

48
Q

What age do calcium deposits occur?

Pain?

Treatment?

A

Elderly patients

Variable comfort

EDTA

49
Q

What can treat corneal pigmentation?

A

Topical steroids/ ciclosporin/ tacrolimus

50
Q

What is this (not pigmented third eyelid)?

What is the treatment?

A

Punctate keratitis

Topics Steroids

51
Q

Nodular granulomatous episclerokeratitis

Where in the eye?

Treatment?

A

Dorso lateral limbus

Topical +/- immunosuppression

52
Q

What is this likely to be?

What can predispose this?

A

Squamous cell carcinoma

Chronic keratitis

53
Q

Lipid (Crystalline stromal) dystrophy

Age of dogs?

Where in the eye?

Inflammation?

Treatment?

A

Young dogs

Central/ para central

No signs of inflammation

Nothing unless abnormality in bloods then treat that!

54
Q

Where is lipid deposited in lipid keratopathy?

A

Stroma

55
Q

Arcus lipoides

Uni/ bilateral?

Associated with?

Vascularisation?

A

Bilateral

Hyperlipidaemia (always), triglycerides

Variable vascularisation

56
Q

Treatment of endothelial dystrophy?

A

NaCl
Thermal keratoplasty
Partial gunderson flaps

57
Q

Which vaccine is this associated with?

Pathophysiology

Treatment?

A

Adenovirus

Type III immunoresponse, antigen antibody deposition on the endothelium

Pred forte QID
NSAIDs

58
Q

What topical treatment is used for fungal infection?

A

Voriconizole

Clotrimazole

59
Q

What are the signs to look for for an ulcer that will possibly melt?

A

Brachycephalic
More oedema than would expect
Punctate ulcer
360’ vascularisation

60
Q

What drops do you use in corneal cross linking?

What does it do?

A

Riboflavin - vit b2

Stabilises cornea and sterilises

61
Q

What is the lamina fusca?

A

Transition zone between sclera and outer choroid and ciliary body

62
Q

What is the lamina cribrosa?

A

where the optic nerve leaves the globe

63
Q

Nodular granulomatous episclerokeratoconjunctivitis

Where?

Cause?

What do they cause?

A

Dorso lateral limbus

Immune mediated

Raised area

Module 6 Cornea Sclera And Episclera (1 decks)

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