Equine Ophthalmology Flashcards

1
Q

Give some clinical signs of ulcerative keratitis

A
  • Bleparospasm
  • Pain
  • Epiphora (excessive eye-watering)
  • Photophobia
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2
Q

What other stain can you use on the eye to check for ulcers?

A

Rose bengal

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3
Q

Which part of the cornea is damaged with superficial ulcers?

A

Only the epithelium

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4
Q

How do you treat a superficial ulcer?

A
  • Topical antimicrobials +/- topical atropine

- Healing rate= 0.6mm/day

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5
Q

Which part of the cornea is damaged with deeper ulcers?

A
  • Stroma

- Scarring likely

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6
Q

What is keratomalacia?

A

Melting ulcer

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7
Q

What causes a melting ulcer?

A

Activation and/or production of proteolytic enzymes by:

  • Corneal epithelial cells
  • Leucocytes
  • Microbial organisms (Pseudomonas)
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8
Q

Which bacteria is likely to be in an eye with a melting ulcer?

A

Pseudomonas

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9
Q

How do you treat keratomalacia (melting ulcers) and descemetoceles?

A
  • Topical serum
  • Topical EDTA
  • Topical acetylcysteine
  • Topical tetracyclines or doxycycline
  • Systemic NSAIDs eg flunixin
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10
Q

What is a descemetacele?

A
  • Melting ulcer that penetrates down to the Descemets membrane
  • Will be fluoroscein-negative
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11
Q

How do you treat a stromal abscess?

A
  • Antimicrobials (eg fluoroquinalones)

- May need surgery (debridement or corneal grafting)

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12
Q

What causes viral keratitis?

A

EHV-2

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13
Q

How would you recognise viral keratitis?

A
  • Multiple superficial, white, punctate or linear opacities

- Varying degree of ocular pain

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14
Q

How do you diagnose viral keratitis?

A

Difficult: virus isolation +/- PCR

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15
Q

How do you treat viral keratitis?

A
  • Topical aciclovir
  • Topical idoxuridine
  • Topical Trifluorothymidine
  • Topical Aciclovir
  • Topical Interferon γ
  • Topical corticosteroid?
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16
Q

Are immune-mediated keratopathies usually unilateral or bilateral?

A

Unilateral

17
Q

How do you treat an immune-mediated keratopathy?

A
  • Medical: topical corticosteroid, cyclosporine A, doxycycline
  • Surgical: keratectomy, cyclosporine A implant
18
Q

What can happen if uveitis is left untreated?

A

Blindness

19
Q

What are the 2 ways anterior uveitis can occur?

A
  • Primary (ie eye trauma)

- Secondary to systemic disease (eg Rhodococcus, Leptospira)

20
Q

Give the clinical signs of anterior uveitis

A
  • Pain: blepharospasm and epiphora
  • Chemosis
  • Constricted pupil
  • Aqueous flare (milky appearance of anterior chamber)
  • Blood, pus or fibrin in anterior chamber)
21
Q

How do you treat uveitis?

A
  • Topical corticosteroids (if no ulcer)
  • Topical atropine (q 4 hours until pupil dilates)
  • Topical NSAID (if ulcer)
  • Topical antimicrobial? (if ulcer)
  • Systemic NSAID (flunixin)
  • Surgery: cyclosporine A implant, enucleation?
22
Q

Give some long-term complications of uveitis

A
  • Atrophy granula iridica
  • Synechiae
  • Cataracts
  • Glaucoma
  • Retinal pathology
  • Blindness
  • Phthisis bulbi
23
Q

‘Butterfly’ lesions around the optic disc are associated with which condition?

A

Uveitis

24
Q

What is the normal intraocular pressure of a horse?

A

15-30 mmHg

25
Q

Give some clinical signs of glaucoma

A
  • Hydrophthalmos/buphthalmos
  • Corneal oedema
  • Corneal striae
  • Lens luxation
  • Blindness
26
Q

How do you medically treat glaucoma?

A
  • Carbonic anhydrase inhibitors: topical (dorzolamide) and/or systemic (acetazolamide)
  • Topical beta blockers: timolol
  • Anti-inflammatories: NSAIDs and/or corticosteroids, topical and/or systemic
27
Q

How do you surgically treat glaucoma?

A
  • Laser destruction of ciliary body
  • Aqueous shunts
  • Enucleation
28
Q

95% of the retinal blood supply is provided by what?

A

Choroid vessels

29
Q

Why should you be careful when using atropine?

A

Can cause gut stasis -> colic