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Ophthalmology (all species) > Ophthalmology Conjunctiva and Cornea > Flashcards

Ophthalmology Conjunctiva and Cornea Flashcards

1
Q

What type of epithelium is the conjunctiva

A

Non-keratinised stratified squamous epithelium

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2
Q

Special cells in different locations of conjunctiva

A

At fornix: mucus producing goblet cells
At limbus: antigen-presenting langhans cells

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3
Q

In what parts of the eye is the conjunctiva closely adhered to the underlying substantia propria

A

At limbus (where it is continuous with corneal epithelium)
In the eyelid

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4
Q

Normal resident population on the eyelid

A

Gram +ve cocci
- Staph intermedius
- Diphtheroids

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5
Q

3 layers of the cornea

A

Corneal epithelium (strat squamous)
Stroma
Endothelium

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6
Q

Characteristics of corneal epithelium repair and fluorescein staining

A

Stem cell population at the limbus; cells migrate the centre
Ulcer should heal within 5 days due to this
Epithelium = barrier to water-borne molecules; fluorescein only taken up when there is a break in epithelium

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7
Q

Corneal stroma characteristics

A

Made of collagen fibrils arranged 20nm apart (<wavelength of light) so cornea is transparent
When water gets into the cornea distorts the fibrils and causes opacity
= barrier to non-aqueous things

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8
Q

Corneal endothelium characteristics

A

Pumps water out to keep cornea transparent (relatively dehydrated)
NB: limited healing capacity except in young animals so any damage from trauma or high pressure is likely perminent

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9
Q

Why can corneal ulcers can miosis

A

Due to nociceptive trigeminal nerve supply

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10
Q

How must drugs be designed to cross the whole cornea

A

Must have polar and non-polar moiety
- Because the epithelium is a barrier to polar substances
- Stroma is a barrier to non-polar things (non-aqueous)
e.g chloramphenicol, dexamethasone alcohol, prednisolone acetate

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11
Q

What are dermoids
- Which breed and where are they commonly found

A

Congenital misplacement of normal skin tissue often with hair
- Seen in brachycephalics at medial canthus

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12
Q

Mechanism behind corneal scarring

A

Collagen fibrils caused to aggregate e.g alkali burn from lime

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13
Q

what material should be used to close the cornea

A

8/0 vicryl

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14
Q

What is chronic superficial keratitis; presentation, aetiology, breed

A

= CD4 T lymphocyte mediated keratitis seen in german shepherds wit UV light as a factor
Presents as a vascular, fibroblastic sheet of pannus
Treatment with lifelong topical steroid or cyclosporine

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15
Q

What breed is predisposed to punctate keratitis and what is it

A

Daschunds
= a multifocal immune mediated keratitis

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16
Q

What do we see with feline eosinophilis keratitis

A

White infiltrating cellular mass
Can have vascularisation and cottage cheese deposit
Cytology shows inflammatory infiltrate with lots of eosinophils

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17
Q

What is corneal oedema and general cause

A

= build up of water in the stroma due to endothelial incompetence

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18
Q

How can corneal odema lead to non-healing ulcers

A

Generation of epithelial bullae which then rupture

19
Q

What are lipid keratopathies assoacited with

A

Prior corneal pathology; new vessels forming to repair the lesion are leaky so lipid escapes

20
Q

What is lipid arcus associated with

A

Hyperlidiaemia
e.g in diabetes mellitus, hypothyroidism

21
Q

What does a thin ring of lipid <few mms in eye mean

A

Stromal lipid dystrophy = due to stromal metabolic defect NOT systemic abnormality

22
Q

Difference in effects of acid vs alkali chemical exposure of cornea

A

For acid, irrigation usually enough
FOr alkali, can lead to melting ulcers and may need to remove affected tissues

23
Q

What is corneal dystrophy also known as

A

Boxer ulcer

24
Q

How does corneal dystrophy work

A

Problem in relationship between corneal epithelial cells and basement membrane; may relate to fewer hemidesmosomes
-> Get impaired movement of cells across the surface of the eye and cells not well adhered
so ulcers can’t heal

25
Q

Treating boxer ulcer/corneal dystrophy

A

Debride off the detached epithelium using a diamond burr
= Grid keratotomy

26
Q

Infectious causes of corneal ulceration

A

FHV-1; see classic dendritic ulcers
Pseudomonas; produces MMPs to destroy collagen to allow bacteria in and breaks down cornea (can get melting ulcer if neutrophils also product MMPs)

27
Q

Endogenous causes of corneal ulceration

A

Keratoconjunctivitis sicca
Corneal dystrophy (leads to boxer ulcers)

28
Q

What are dendritic ulcers pathognomic of

A

FHV-1 infection

29
Q

What leads to development of a melting ulcer

A

INvading bacteria (e.g pseudomonas) produce MMPs/collagenases to break down cornea
Neutrophils respond and also produce MMps

–> Get breakdown of tissue and melting ulcer

30
Q

What alternative (to diamond burr) method can we use to perform grid keratotomy in non healing superficial ulcer

A

Tetracaine first
Then just use cotton bud

31
Q

How would we deal with a midstromal depth healing ulcer

A

Put in a contact lens to protect the eye

32
Q

What does a clear part in the middle of an ulcer which is non-oedematous suggest

A

Stroma here has been lost; this is a deep ulcer

33
Q

Possible treatment option for a deep/non-healing ulcer

A

Conjunctival pedicle flap; used to cover ulcer
Gives physical support and blood borne factors

34
Q

What is the appearance of a melting ulcer and what is the risk that might happen

A

Corne turns white and fluid
_ risk is perforation of the cornea

35
Q

How to treat a melting ulcer

A

Vigorous antibiosis e.g fluoroquinolones, gentamycin
Anticollagenase treatment: autologous serum (contains macroglobulins), acetyl cystine (binds zinc), EDTA (binds calcium)

36
Q

WHat kind of sutures could we use to hold the cornea together in case of large melting ulcer

A

mattress sutures; until it heals

37
Q

What is a corneal sequestrum and what species is it seen in

A

Cats
= black/brown necrotic area of stroma

38
Q

Symptoms of conjunctivitis

A

Redness is seen on the lid and the globe mucosa
Oedema
Irritation with some blepharospasm but not severe pain
Ocular discharge
Lymphoid changes

39
Q

In which breed of dogs do we see immune-mediated conjunctivitis and what is the aetiology

A

German shepheds
= lymphocytic-plasmocytic conjunctivitis
+ also see depigmentation of 3rd eyelid due to cellular infiltrate

Treatment = lifelong steroid drops or cyclosporine drops

40
Q

What infectious causes of conjunctivitis in cats

A

FHV-1 (treat with famciclovir)
CHlamydial ; unilateral then bilateral; treat with tetracyclines
+ bacteria

41
Q

What virus can cause conjunctivitis in dogs

A

Canine distemper

42
Q

Which antibiotic is good for the eye (due to molecular properties)

A

Chloramphenicol

43
Q

Which dogs do we see pigmentary keratitis. in

A

Brachcephalics with prominent globes and nasal fold hair
Dry eye

Ophthalmology (all species) (8 decks)

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