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Opthalmology > Equine Opthalmology > Flashcards

Equine Opthalmology Flashcards

1
Q

What mydriatic should you use to aid fundic examination?

A

Tropicamide - duration - 4 to 6 hours

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2
Q

What diopter should you have the ophthalmoscope set at for close direct opthalmoscopy at different levels in the equine eye?

A

0 to -3D - fundus
+2 to 6D - vitreous
+7 to +8D - lens
+10D - cornea

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3
Q

What can a split lamp be used for?

A

Assessing the depth of lesions in the eye

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4
Q

How can you perform the auriculopalpebral nerve block?

A

Blocks the motor fibres of the auriculopalpebral n. VII
Does not provide analgesia
Run the finger down the orbital rim and feel the nerve ping under your finger
Instil 5ml of local

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5
Q

Describe the frontal / supra orbital nerve block

A

Provides analgesia to the eye
Supraorbital branch of V blocked
Palpation the the supra orbital process on the frontal bone, where the nerve emerges from the supra orbital foramen
Instill 2ml of local, then pull back slightly and inject another ml
Desensitises the middle 2/3 of the upper eyelid

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6
Q

How does a superficial ulcer appear after fluorescein staining?

A

Sharp edges
No under running of the epithelium
No stain migration

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7
Q

How does an indolent ulcer appear with fluorescein staining?

A

Epithelium is under run

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8
Q

How do deep storm all ulcers stain with fluorescein?

A

Very intense staining, stain migration occurs in 5-15mins

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9
Q

How do desmetocoeles stain with fluorescein?

A

Wall of the ulcer stains intensely

Central area with no stain uptake

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10
Q

What does the seidel test demonstrate?

A

Aqueous leakage - stream of fluorescein where the aqueous is leaking

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11
Q

What can rose Bengal stain be used for?

A

Assessing the tear film
Assessing the margins of conjunctival and corneal neoplasia
Fungal ulcers

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12
Q

How can you take a cytology sample of the eye?

A

Cytology brush

Don’t put local anaesthetic on before - sterilises the eye

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13
Q

What locations are associated with better prognoses with eyelid lacerations?

A

Lower eyelid better than upper eyelid

Lateral eyelid better than medial eyelid

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14
Q

What is TOC for sarcoids around the eye?

A

Radiotherapy / brachytherapy

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15
Q

What is the prognosis of eyelid tumours following surgery?

A

SSC - variable - follow up with chemo/RT

Melanoma - good

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16
Q

What is the most common corneal problem in horses?

A

Ulcerative keratitis

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17
Q

What are the clinical signs of ulcerative keratitis?

A

Blepharospasm
Epiphora
Pain
Photophobia

18
Q

What should you treat superficial ulcerative keratitis with in the horse?

A

Topical antimicrobials
Topical atropine - for reflex uveitis
+/- serum

Good prognosis if managed correctly

19
Q

How should you treat deep ulcers in the horse?

A

Prolonged course compared to superficial ulcers
Topical antibiotics
Topical atropine
Serum

20
Q

What is the pathogenesis of keratomalacia in the horse?

A

Activation of proteinuria enzymes in the cornea by epithelial cells, leukocytes and pseudomonas

Requires early aggressive therapy

21
Q

How should you treat keratomalacia?

A

Topical serum
Topical CaEDTA - chelates Ca so pro teases can’t activate
Topical acetylcystine - maintains the tear film
Topical tetracycline / doxycycline - inhibits MMPs
Flunixin

22
Q

How should you treat a descemetocole?

A

Flunixin
Atropine
Refer for surgery - conjunctival flap

23
Q

How should you treat a non-ulcerative keratitis/stromal abscess?

A

Atropine
Chloramphenicol - gentamycin is not adequate
Refer for surgery - debridement or corneal graft

24
Q

How does equine herpes virus 2 viral keratitis present?

A

Multiple, superficial, punctate ulcers

Variable staining with rose Bengal and fluorescein

25
Q

How can you treat this?

A

Topical acyclovir

Topical idoxuridine

26
Q

How is fungal keratitis diagnosed?

A

Cytology essential - sample deep into the cornea

27
Q

How can you treat fungal keratitis?

A

Voriconazole- antifungal of choice

Warn owners it is likely to get a lot worse in the first 24 hours due to the massive death of fungi

28
Q

How do immune mediated keratopathies usually present?

A 
Insidious onset
Unilateral
No uveitis - not very painful 
Superficial - irregular corneal surface
Deep - bullae formation, vascularisation and oedema
29
Q

How can you treat immune mediated keratopathies?

A

Medical management
- topical corticosteroids, cyclosporine A, doxycycline

Surgical
- keratomy, cyclosporine a implant

30
Q

What are the clinical signs of anterior uveitis?

Iris and ciliary body

A 
Blepharospasm
Epiphora 
Chemosis
Miosis
Aqueous flare - leakage of lens proteins 
Hyphaema 
Hypopyon
Fibrin in the anterior chamber
31
Q

What is clinical presentation of posterior uveitis? Choroid

A

Low grade ocular discomfort

32
Q

How can you treat uveitis?

A 
Treat underlying cause
Flunixin
Topical corticosteroids if no ulcer
Topical antimicrobials 
Topical atropine - care may cause colic and ileus
33
Q

What surgical options are available for the management of uveitis?

A

Suprachoroidal cyclosporine A implant
Pars plana vitrectomy - only really for uveitis due to lepto
Enucleation

34
Q

Signs to look for during a vetting to assess whether a horse has had uveitis in the past.

A

Atrophy of the granula iridica and irregular pupil margin
Anterior synechiae - iris adhered to cornea
Posterior synechiae - iris adhered to the lens
Cataracts
Glaucoma
Blindness
Retinal pathology
Phythisis bulbi

35
Q

What are the two causes of cataracts in horses?

A

Acquired - uveitis, trauma, tumour
Developmental - congenital in foals

Most don’t require treatment - not progressive and have little effect on vision

Can be removed by phacoemulsification

36
Q

List the types of cataracts found in horses.

A 
Capsular cataract 
Nuclear cataract
Perinuclear cataract
Equatorial cataract 
Sutural cataract
Complete cataract
37
Q

What is the drainage angle in the horse?

A

Conventional angle - pectinate ligaments

Unconventional angle - big blood vessels in the ciliary body

38
Q

How can you diagnose glaucoma?

A 
Hydrophthalmos
Bupthalmos
Corneal oedema
Corneal striae
Lens luxation
Blindness
39
Q

How can you diagnose glaucoma?

A

Tonopen

Enlarged eye

40
Q

How can you treat glaucoma?

A

Dorzolamide - topical carbonic anhydrase inhibitor
Timolol - beta blockers
Flunixin
Topical corticosteroids

Prostaglandin derivative are CI in horses

41
Q

How can the colour of a retinal lesion indicate its depth?

A 
Neurosensory retina - cling film
Retinal pigment epithelium - black
Tapetum - blue, green, Amber
Choroid - red
Sclera - White

Opthalmology (1 decks)

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