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Opthalmology > Equine > Flashcards

Equine Flashcards

1
Q

What percentage of the optic disc can be seen using direct opthalmoscopy?

A

2%

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2
Q

What value of magnification is required to see the various structures in the eye with direct opthalmoscopy?

A

Fundus 0-(-3), Vitreous 2-6, Lens 7-8, Cornea 10

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3
Q

What is the function of a slit lamp?

A

Assesses depth of lesions - see light mark at a change in refraction (should only see three normally)

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4
Q

What nerves are assessed with PLR?

A

Optic and occulomotor - unconscious

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5
Q

What nerves are assessed with the menace response?

A

Optic and facial - conscious (forebrain)

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6
Q

What nerve blocks could be performed in order to assess the painful eye?

A

Frontal - sensory trigeminal, auriculopalpebral - motor facial

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7
Q

Describe the action of fluorescein dye.

A

It is hydrophilic and hence adheres to exposed stroma and runs off intact lipid epithelium. It turns from orange to green in alkaline conditions

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8
Q

Which part of the cornea DOES NOT stain with fluorescein?

A

Descemets membrane

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9
Q

What is the function of rose bengal dye?

A

Used to assess fungal ulceration and tear film

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10
Q

What mydriatic agent is most commonly used in horses?

A

Tropicamide

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11
Q

Mydriacyl

A

Tropicamide

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12
Q

What clinical signs are associated with ulcerative keratitis?

A

Pain, blepharospasm, epiphoria, photophobia

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13
Q

What are the most common neoplastic conditions associated with the eye?

A

Sarcoid, SCC, lymphoma (3rd eyelid), melanoma

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14
Q

Describe this lesion & its treatment.

A

Sharp edges, focal, no under-running or stain migration. Superficial ulcerative keratitis.

Treatment: topical antimicrobials and atropine

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15
Q

Describe this lesion and its treatment

A

An indolent ulcer with corneal under-running. Treatment - antimicrobials and atropine with debriding of dead corneal tissue

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16
Q

Describe this lesion and its treatment. What are the expected outcomes?

A

Will show intense staining, deep stromal abscessation. Can use a slit lamp to assess depth.

Treatment: topical antimicrobials + atropine. It is likely there will be corneal scarring after healing

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17
Q

Describe this lesion and its treatment.

A

Walls of the ulcer stain intensely with stain migration. There is a central area of destaining.

Descematocele

Aggressive therapy needed - EDTA, Serum, acetylcystein, antibiotics (tetracycline/ doxycycline)

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18
Q

Which analgesic agent is particularly useful for eye pain?

A

Flunixin (bute alternatively)

19
Q

What is the function of serum in eye cases?

A

Anti-protease

20
Q

What is the function of doxycycline in eye cases?

A

Antimicrobial and also inhibits MMPs (inhibits keratomalacia)

21
Q

What is the function of EDTA in eye cases?

A

Ca2+ chelation - Calcium often works as a co-factor for enzymes causing keratomalacia.

22
Q

Why does keratomalacia occur?

A

Release of enzymes from epithelial cells, leucocytes and microbes causing breakdown of the cornea

23
Q

What treatment protocol should be used in a case of keratomalacia?

A
  • Serum
  • EDTA
  • Acetylcysteine
  • Tetracycline/ doxy
  • Surgical debridement
  • NSAIDs
24
Q

Why should you NOT use atropine for a case of full thickness corneal laceration with iris prolapse?

A

The iris is plugging the hole and preventing full rupture of the eye. Atropine will cause its contraction!

25
Q

Ulceration of which area of the eye will be most painful and why?

A

Superficial cornea - due to the greater presence of nervous tissue

26
Q

Name three antibiotics commonly used to treat eye conditions.

A

Chloramphenicol, fluoroquinolones, aminoglycides (gentamycin), tetracycline (doxycycline)

27
Q

What bacterial species are most associated with ulcerative keratitis?

A

Pseudomonas, staphylococcus and beta-haemolytic streptococcus

28
Q

What fungal species are most associated with non-ulcerative keratitis?

A

Aspergillus, fusarium, penicillum

29
Q

Describe this lesion and its description.

A

Stromal abscessation - will be fluorescein negative.

Medical therapy includes antibiotic therapy and surgical therapy includes debridement or corneal rupture.

30
Q

What virus is a cause of non-ulcerative keratitis?

A

EHV-2

31
Q

What diagnostics would be useful with a suspected case of fungal keratits?

A

Cytological brush samples - DEEP sampling!

32
Q

What antifungals are most commonly used in cases of fungal keratitis?

A
  1. Miconazole - narrow spectrum
  2. Voriconazole - broad spectrum
  3. Itraconazole
33
Q

Describe this lesion and its treatment.

A

Faint fluoroscein uptake - likely an immune-mediated keratopathy.

Treatment - topical steroids, cyclosporin (or implant), doxycycline,

34
Q

What structures of the eye are considered as the uvea?

A

Choroid, RPE, iris and ciliary body

35
Q

What clinical signs are associated with anterior uveitis?

A
  • Blephrospasm
  • Epiphora
  • Chemosis
  • Aqueous flair
  • Hyphaema
  • Hypopyon
  • Abnormal colouring of the iris
  • Blindness
36
Q

What clinical signs are associated with posterior uveitis?

A

Ocular discomfort, altered vitreous, blindness

37
Q

What treatment is used in cases of uveitis?

A
  1. Corticosteroids - if no ulcers
  2. NSAIDs if ulceration is seen
  3. Atropine - dilation and prevention of adhesions - every 4 hours until dilation
  4. Systemic flunixin
  5. +/- cyclosporin inplants, vitriectomy/ enucleation
38
Q

What long term lesions are suggestive of previous uveitis?

A

Synechiae, atrophy of the granula iridica, cataracts, retinopathy (bullet hole lesions, butterfly lesions), blindness, phthisis bulbi

39
Q

Which types of cataracts tend to be non-progressive?

A

Capsular, peri-nuclear (may change), equitorial

40
Q

What types of cataract tend to be progressive?

A

Sutural, nuclear (uveitis), complete

41
Q

What pressure is considered a positive diagnosis of glaucoma in the horse?

A

>15-30 mmHg

42
Q

What clinical signs are associated with glaucoma?

A
  • Hydrophthalmos
  • Exosphthalmos
  • Corneal oedema
  • Corneal striae
  • Lens luxation
  • Blindness
43
Q

What treatments are often used for cases of glaucoma and why?

A
  1. Carbonic anhydrase inhibitors - diuresis - dorzolamide
  2. Beta-blockers - timolol
  3. Anti-inflammatories
  4. PGE
  5. Laser destruction of the ciliary body
  6. Enucleation
  7. Aqueous shunts
44
Q

What is meant by Paurangiotic optic disc?

A

Minimal blood vessels seen - mostly choroidal vessels

Opthalmology (3 decks)

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