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Module 6 Cornea Sclera And Episclera > Cornea > Flashcards

Cornea Flashcards

(63 cards)

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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
What are the clinical signs of superficial punctate keratitis? Which breeds are predisposed?
Multiple fluoro positive corneal opacities (white) Shetland sheepdogs Min LH daschunds
26
What is this likely to be (dog)? Single/multiple raised lesion dorsolateral limbus What is the treatment?
Nodular granulomatous episcleritis Topical +/- immunosuppression
27
Limbal/ epibulbar melanoma are common in what type of dogs? Treatment?
Darkly pigmented dogs; Labs GSD Excise +/- adjunctive therapy
28
What could be the cause of corneal lipidosis?
``` Just inherited Primary hyperlipidaemia DM HyperA Hypothyroidism ```
29
Does corneal lipidosis cause inflammation? Bilateral/ uni? Location?
No Bilateral Subepithelial, central/para central
30
How is Lipid keratopathy different to lipid dystrophy? | Treatment?
Lipid keratopathy has inflammation and blood vessels | Treat cause of hyperlipidaemia, can do keratectomy/ laser but do this after plasma lipidaemia stable!
31
Which causes with which? ``` Larger lipoproteins (triglyceride rich) Smaller lipoproteins (cholesterol rich) Causes… Lipid keratopathy Arcus lipoides corneae ```
Larger lipoproteins (triglyceride rich) cause Arcus lipoides corneae Smaller lipoproteins (cholesterol rich) Causes Lipid keratopathy
32
PDT can cause what type of corneal opacity?
Calcification
33
What is the breed predilection for dermoids?
GSD | St Bernard’s
34
What is the purpose of thermal keratopasty in endothelial dystrophy? How does it do this?
Preventing corneal ulceration. Post operative fibrosis of the corneal stroma squeezes fluid out and prevents further fluid entry.
35
Which breed of cat is stromal dystrophy found in? | Uni/ bilateral?
Manx cat | Bilateral
36
Which breed is macular corneal dystrophy seen in? What age? What are the clinical signs? What test can be done? Cause?
Lab Middle aged (~5yo) Stromal opacity +/- vascularisation DNA - carbohydrate sulfotransferase 6 Accumulation of glycosaminoglycan
37
What is the treatment for epithelial inclusion cyst?
Surgical excision
38
What is the treatment for stromal keratitis in cats with FHV?
Antivirals + steroids
39
What appearance on the cornea does mycotic keratitis have?
White (icing sugar) appearance
40
Within what time should an uncomplicated ulcer heal?
7days
41
How long should you use a diamond burr on a SCCED for?
45-60secs
42
What enzymes cause the stroma digested causing a melting ulcer? What are these enzymes produced by?
Proteases and collagenases Pathogenic organisms, inflammatory cells, resident corneal cells
43
What is the purpose of corneal cross linking?
Stabilise and sterilise the cornea
44
Describe these 3 layers of the epithelium?
Top- squamous cells Middle - intermediate wing cells Bottom- Columnar cells (regenerating)
45
What is this? What part of the eye has to be defected for this to occur?
Corneal hydrops Descemets membrane
46
What cells have to be damaged for oedema to enter cornea?
Epithelial cells | Endothelial cells
47
What are white/tan precipitates In the eye? What do they indicate? Where do they stick to?
Keratic precipitates Uveitis Endothelium
48
What age do calcium deposits occur? Pain? Treatment?
Elderly patients Variable comfort EDTA
49
What can treat corneal pigmentation?
Topical steroids/ ciclosporin/ tacrolimus
50
What is this (not pigmented third eyelid)? What is the treatment?
Punctate keratitis Topics Steroids
51
Nodular granulomatous episclerokeratitis Where in the eye? Treatment?
Dorso lateral limbus Topical +/- immunosuppression
52
What is this likely to be? What can predispose this?
Squamous cell carcinoma Chronic keratitis
53
Lipid (Crystalline stromal) dystrophy Age of dogs? Where in the eye? Inflammation? Treatment?
Young dogs Central/ para central No signs of inflammation Nothing unless abnormality in bloods then treat that!
54
Where is lipid deposited in lipid keratopathy?
Stroma
55
Arcus lipoides Uni/ bilateral? Associated with? Vascularisation?
Bilateral Hyperlipidaemia (always), triglycerides Variable vascularisation
56
Treatment of endothelial dystrophy?
NaCl Thermal keratoplasty Partial gunderson flaps
57
Which vaccine is this associated with? Pathophysiology Treatment?
Adenovirus Type III immunoresponse, antigen antibody deposition on the endothelium Pred forte QID NSAIDs
58
What topical treatment is used for fungal infection?
Voriconizole | Clotrimazole
59
What are the signs to look for for an ulcer that will possibly melt?
Brachycephalic More oedema than would expect Punctate ulcer 360’ vascularisation
60
What drops do you use in corneal cross linking? What does it do?
Riboflavin - vit b2 Stabilises cornea and sterilises
61
What is the lamina fusca?
Transition zone between sclera and outer choroid and ciliary body
62
What is the lamina cribrosa?
where the optic nerve leaves the globe
63
Nodular granulomatous episclerokeratoconjunctivitis Where? Cause? What do they cause?
Dorso lateral limbus Immune mediated Raised area

Module 6 Cornea Sclera And Episclera (1 decks)

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