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Ophthalmology > Unit 2 - Equine Ophtho > Flashcards

Unit 2 - Equine Ophtho Flashcards

(65 cards)

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1
Q

Explain the visual field of horses.

A

Due to their lateral eye placement - total horizontal visual field (350 degrees), binocular visual field (60)

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2
Q

What are the unique parts of equine iris ocular anatomy?

A

Corpora nigra/Granula iridica

Pupil shape

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3
Q

What are the unique parts of fundus equine anatomy?

A

Paurangiotic retina

Stars of winslow

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4
Q

The main nourishment of the equine retina is via what?

A

The Starrs of Winslow

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5
Q

What type of vision does the horse have?

A

Dichromatic

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6
Q

What should be used to facilitate te equine eye exam?

A

Dark environment

Sedation

Nose twitch

Periocular nerve blocks

topical anesthesia

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7
Q

What are the components of the equine eye exam?

A

General distance exam

Cranial nerve testing

Ophthalmic diagnostics

Adnexa and globe exam

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8
Q

T/F: Fluoresceine staining should be performed for every horse eye exam.

A

True

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9
Q

When I say the fluoroscein stain was positive, what does that mean?

A

There is an ulcer - the fluorescein attaches to the stromal layer

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10
Q

Aside from looking for an ulcer, what is fluorescein stain good at testing for?

A

It simultaneously does the Jones test - tests nasolacrimal duct flushing (we want a positive test)

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11
Q

What is the normal IOP of the horse?

A

15-30 mmHg

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12
Q

Tonometry should be performed at what level in the horse?

A

At or above heart level

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13
Q

What are the preferred tonometry instruments for horses?

A

TonoVet or TonoVet+

Tonopen is not ideal

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14
Q

What does the auriculopalpebral block block?

A

Motor innervation to the orbicularis oculi

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15
Q

What sensory nerve blocks can be done in the horse?

A

Frontal/Supraorbital

Infratrochlear

Lacrimal

Zygomatic

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16
Q

What is the most common equine eye/adnexal tumor?

A

Squamous cell carcinoma

If you see a mass around the eye you should think SCC

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17
Q

What are the most common locations for SCC in the horses eye?

A

Eyelids, third eyelid, conjunctiva, and limbus/cornea

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18
Q

What are the predisposing factors for SCC?

A

Ultraviolet radiation

Lack of periocular pigmentation

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19
Q

How do SCC present?

A

Initially hyperemic area progressing to ulceration (lids) then to papillomatous and fleshy masses

Varying degrees of ulceration, necrosis, and inflammation

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20
Q

What is the therapeutic goal of SCC?

A

Destroy the tumor while preserving ocular function and cosmesis

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21
Q

What is the recommended treatment for SCC?

A

Surgical excision and adjunctive therapy - there are a lot of options

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22
Q

How often should a horse be reevaluated if they have had SCC removed?

A

Every 6months for life

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23
Q

Where can SCC locally invade? Metastasize?

A

Invade - soft tissue, boney orbit, sinuses, brain

Metastasize - LN, salivary glands, thorax

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24
Q

At what location do SCC have the highest recurrence rate?

A

Eyelid or third eyelid

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25
What are the prevention strategies for SCC?
UV light protection mask Eyelid tattooing
26
What is the usual cause of corneal ulceration?
Trauma
27
What are the keys to success of corneal ulcer management?
Diagnose early Treat appropriately Monitor closely
28
What are the complicating factors for corneal ulceration management?
Infection Melting
29
What is important to aid in diagnosis of corneal ulcers?
Adequate restraint/sedation, nerve blocks, topical anesthesia Examine for FB Fluoresscein stain
30
What should be done if there are infected, melting, or stromal defects on the eye?
Culture and sensitivity Cytology
31
What is the recommended therapy for simple ulcer management?
Topical broad spectrum antibiotic TID-QID - NO STERIOD Atropine 1% ointment SID-BID then taper Systemic Anti-inflammatory - Flunixin meglumine, phenylbutazone
32
What side effect can atropine cause in horses?
Colic
33
When should simple ulcers be rechecked in horses?
3-5 days
34
What are the forms of complicated corneal ulcers?
Nonhealing Infected Melting Deep or ruptured
35
What are the infectious causes of complicated corneal ulcers?
Bacterial - Staphylococcus, Streptococcus, Corynebacterium, Pseudomonas Fungi - Aspergillus, Fusarium
36
It is difficult to give horses liquid medications constantly, what can be done to mitigate this and allow for the treatments?
Subpalpebral lavage line
37
How are complicated corneal ulcers treated?
Topical antibiotic solutions - **ciprofloxacin,** ofloxacin, gentamicin, **tobramycin,** **chloramphenicol**, cefazolin Oral NSAID BIDx3d then SID: **Flunixin meglumine,** phenylbutazone **Atropine**
38
What are the preferred antifungal medications for the treatment of complicated corneal ulcers?
Topical - **Voriconazole,** Itraconazole, silver sulfadiazine derm cream Systemic - **Fluconazole**
39
In addition to topical abx and anti-inflammatories, what else should be used to treat complicated corneal ulcers?
Antiproteinase/anticollagenase agents: **Serum/plasma q1-2h** EDTA N-acetylcysteine Tetracycline abx +/-Systemic abx
40
What are the monitoring recommendations for complicated corneal ulcers?
Hospitalize or recheck in \<48 hours Weekly therafter if improving Referral if unchanged or worse
41
What can be done to prevent self trauma in complicated corneal ulcer cases?
Eyesaver mask
42
What surgical treatment can be done to treat complicated corneal ulcers?
Keratectomy or corneal debridement Conjunctival +/- collagen graft Corneoconjunctival transposition Corneal and/or amniotic membrane transplantation
43
What can cause deep corneal stromal abscesses?
Infectious agens get trapped within the cornea - either an infected ulcer that epithelializes rapidly or a small puncutre wound that seals
44
What is the clinical appearance of deep corneal stromal abscesses?
Severe pain Fluoresceine negative whiteish yellow stromal opacity Corneal vascularization and edema
45
What must you differentiate deep corneal stromal abscesses from?
Primary uveitis
46
What medication should you not use in cases of primary uveitis?
Steroids
47
How are deep corneal stromal abscesses treated/
Aggressive medical therapy +/- durgical intervention
48
What is the recommended medical treatment for corneal stromal abscesses?
Antimicrobials for bacterial/fungal infection: * Topical **ciprofloxacin** and **chloramphenicol** q 3-6 hrs * Topical **voriconazole** q 3-6 hrs * Systemic fluconazole and SMZ-TMP if vascularized Reflex uveitis treatment: * **Atropine** BID-QID (watch for colic signs!!!) * **Banamine** 1.1 mg/kg BID then slowly decrease * +/- Omeprazole prophylactic dose Subpalpebral lavage line recommended
49
What is the most common cause of equine blindness?
Uveitis
50
What are the numerous causes of uveitis in horses?
Infectious diseases Trauma Neoplasia Idiopathic/immune mediated
51
What are the most common clinical signs associated with uveitis in horses?
Blepharospasm, epiphora, photophobia, conjunctival/episcleral blood vessel injection, aqueous flare, miosis
52
What diagnostic tests should be done for uveitis?
Rule out primary corneal disease CBC/Chemistry Serology - Leptospira
53
How is uveitis treated in horses?
Address the underlying cause Treat eye aggressively then taper
54
How long should uveitis be treated in horses?
2-4 weeks past resolution
55
What topical medications can be used for uveitis therapy?
Anti-inflammatories QID+ * Steroid: dexamethasone 0.1% or prednisolone acetate 1% * Do not use hydrocortisone – weak steroid and can’t penetrate cornea * FLUORESCEIN STAIN BEFORE USING STEROIDS! * NSAID: flurbiprofen 0.03% or diclofenac 0.1% Atropine 1% SID-BID * Monitor for signs of colic, discontinue use if noted
56
What systemic medications are used for uveitis treatment?
Oral anti-inflammatory treatment (NSAID) * Flunixin meglumine 1.1 mg/kg PO SID-BID * Phenylbutazone 1 g PO SID-BID (1000# horse) * Firocoxib (Equioxx®) 40 mg SID (1000# horse)? * Aspirin 25 mg/kg PO SID-BID for maintenance treatment?
57
What is equine recurrent uveitis also known as?
Moon blindness or periodic ophthalmia
58
What breeds are predisposed to ERU?
Appaloosa and draft breeds
59
T/F: ERU is immune-mediated following the trigger
True
60
What are the stages of ERU?
Acute, insidious, or chronic end-stage
61
What complicating issues are associated with ERU?
Calcific band keratopathy Blinding cataract Vitreal floaters or fibrinous traction bands Retinal detachments Secondary glaucoma
62
What are the goals for ERU treatment?
Preserve vision, decrease pain, prevent or minimize recurrence
63
How is ERU treated?
Topical and systemic uveitis treatment -Anti-inflammatories and atropine as noted before Systemic antibiotics - Streptomycin, penicillin, tetra/doxycycline, enrofloxacin Intravitreal injection - 4 mg preservative-free gentamicin Surgical treatment- Vitrectomy, Suprachoroidal cyclosporine implant
64
What is the prognosis of ERU?
POOR
65
What are the components of the pre-purchase examination?
Vision and PLRs Anterior segment exam Lens and posterior segment exam Note: Make sure to cite and discuss all findings

Ophthalmology (13 decks)

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