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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
Ulceration of which area of the eye will be most painful and why?
Superficial cornea - due to the greater presence of nervous tissue
26
Name three antibiotics commonly used to treat eye conditions.
Chloramphenicol, fluoroquinolones, aminoglycides (gentamycin), tetracycline (doxycycline)
27
What bacterial species are most associated with ulcerative keratitis?
Pseudomonas, staphylococcus and beta-haemolytic streptococcus
28
What fungal species are most associated with non-ulcerative keratitis?
Aspergillus, fusarium, penicillum
29
Describe this lesion and its description.
Stromal abscessation - will be fluorescein negative. Medical therapy includes antibiotic therapy and surgical therapy includes debridement or corneal rupture.
30
What virus is a cause of non-ulcerative keratitis?
EHV-2
31
What diagnostics would be useful with a suspected case of fungal keratits?
Cytological brush samples - DEEP sampling!
32
What antifungals are most commonly used in cases of fungal keratitis?
1. Miconazole - narrow spectrum 2. Voriconazole - broad spectrum 3. Itraconazole
33
Describe this lesion and its treatment.
Faint fluoroscein uptake - likely an immune-mediated keratopathy. Treatment - topical steroids, cyclosporin (or implant), doxycycline,
34
What structures of the eye are considered as the uvea?
Choroid, RPE, iris and ciliary body
35
What clinical signs are associated with anterior uveitis?
* Blephrospasm * Epiphora * Chemosis * Aqueous flair * Hyphaema * Hypopyon * Abnormal colouring of the iris * Blindness
36
What clinical signs are associated with posterior uveitis?
Ocular discomfort, altered vitreous, blindness
37
What treatment is used in cases of uveitis?
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
What long term lesions are suggestive of previous uveitis?
Synechiae, atrophy of the granula iridica, cataracts, retinopathy (bullet hole lesions, butterfly lesions), blindness, phthisis bulbi
39
Which types of cataracts tend to be non-progressive?
Capsular, peri-nuclear (may change), equitorial
40
What types of cataract tend to be progressive?
Sutural, nuclear (uveitis), complete
41
What pressure is considered a positive diagnosis of glaucoma in the horse?
\>15-30 mmHg
42
What clinical signs are associated with glaucoma?
* Hydrophthalmos * Exosphthalmos * Corneal oedema * Corneal striae * Lens luxation * Blindness
43
What treatments are often used for cases of glaucoma and why?
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
What is meant by Paurangiotic optic disc?
Minimal blood vessels seen - mostly choroidal vessels

Opthalmology (3 decks)

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