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Eq Special Topics > Equine Eyeballs > Flashcards

Equine Eyeballs Flashcards

1
Q

What is the corpora nigra/granulae iridica?

A

Extension of the posterior iris into the anterior chamber that acts as a “visor” for the pupil and helps control the amount of light reaching the retina

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2
Q

What does the auribulopalpebral nerve block? Why is it important for your ophthalmic exam?

A

Palpebral branch of the palpebral nerve (CN7)
Paralysis of orbicularis oculi muscle (mostly the upper eye)

Helps prevent blinking and clamping down

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3
Q

What are the supraorbital and frontal block anesthetizing? Why is this helpful?

A

Sensory innervation from V1 to elimination sensation to the central upper eyelid

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4
Q

T/F: Normal tear production for horses is over 20mm/min, but tear deficiencies are rare in horses.

A

True

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5
Q

Normal IOP in horses is _______mmHg

A

15-30

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6
Q

TonoPen (applanation tonometry) requires….

A

Topical anesthetic

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7
Q

Fluorescein stain is taken up on the medial aspect of the cornea. Where should you look first?

A

Beneath the third eyelid - looking for a FB resulting in corneal ulceration

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8
Q

What is a Jones test?

A

Fluorescein stain travels thru nasolacrimal duct to test patency

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9
Q

When is irrigation of the NLD indicated?

A

Epiphora, mucoid ocular discharge, nasal puncta discharge

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10
Q

By what two methods can you irrigate the NLD?

A

Normograde from the proximal eyelid puncta
Retrograde from distal nares opening

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11
Q

T/F: Normograde irrigation is easier than retrograde

A

False - retrograde is easier

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12
Q

Posterior synechia is indicative of…

A

Previous uveitis
ERU (Equine Recurrent Uveitis)

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13
Q

When performing indirect fundoscopy, how is the image presented?

A

Inverted (upside down) and reversed

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14
Q

Compare and contrast direct and indirect fundoscopy

A

Direct: smaller field of view w/ more magnification, upright image
Indirect: wider field of view w/ less magnification, inverted and reversed image

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15
Q

What bones compose the COMPLETE bony orbital rim?

A

Frontal
Lacrimal
Zygomatic
Temporal

Deep internal wall: sphenoid, palatine

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16
Q

Most EOM innervated by ______

A

CN3 (oculomotor)

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17
Q

What are the potential causes of a “sunken” appearing globe?

A

Enophthalmos
Microphthalmos
Phthisis bulbi

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18
Q

Causes of enophthalmos

A

Orbital fractures
Resorption of orbital fat
Dehydration in foals (entropion)
Sympathetic denervation (Horner’s)

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19
Q

Enophthalmos is usually secondary to ________

A

Loss of orbital contents

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20
Q

What is microphthalmia?

A

Congenital anomaly resulting in small globe

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21
Q

What is phthisis bulbi?

A

Gradual shrinkage of the globe d/t chronic inflammation and low IOP

Damage to CB results in decreased AH production

Non-visual

Enucleate if uncomfortable

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22
Q

Buphthalmos and exophthalmos result in a _________ appearance

A

Bulging

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23
Q

Buphthalmos is secondary to __________

A

Increased IOP secondary to glaucoma

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24
Q

What is the difference between buphthalmos and exophthalmos?

A

Buphthalmos involves a bigger globe
Exophthalmos is the anterior displacement of the globe

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25
In addition to buphthalmos, what other ocular signs might you see?
Haab’s striae Corneal edema
26
Potential causes of exophthalmos
Retrobulbar mass Orbital cellulitis/abscess Trauma
27
Most common location of orbital fractures?
Dorsal orbital rim and zygomatic arch d/t prominent location
28
How can you diagnose orbital fat prolapse?
FNA or biopsy - will come back as just fat
29
Treatment for orbital cellulitis
Systemic antimicrobial agents Aggressive NSAIDs Lubricants Drainage of abscess (if present) Removal of FB (if present) Enucleation
30
What is the most important diagnostic tool for orbital disease?
Imaging! CT, MRI, US
31
Important functions of the eyelid
Protection (blinking) Entrapment and removal of material Distribution of tears Production of glandular secretions (meibomian glands)
32
Movement of the third eyelid is __________, meaning the structure is not controlled by a muscle.
indirect
33
In what population is entropion most common?
Congenital ocular abnormality in FOALS
34
CS of entropion
Epiphora Corneal ulcer Conjunctivitis Blepharospasm Keratitis
35
Describe a temporary tacking procedure
Vertical mattress suture using 4 to 6-0 non-absorbable monofilament suture left in for 2-3 weeks
36
Though rarely required, describe how to permanently correct entropion
Hotz-Celsus procedure Incision 2-2.5mm from and parallel to eyelid margin, extending slightly medial and lateral to region of entropion Second incision defines amount of skin being removed Excise skin and underlying strip of orbicularis Simple interrupted skin closure (bisecting)
37
How do we treat eyelid lacerations?
PROMPTLY Standing under sedation or GA w/ local blocks Clean wound w/ saline or dilute betadine MINIMAL DEBRIDEMENT Primary closure!!! 2 layer closure (tarsoconjunctival and musculocutaneous)
38
Discuss post-operative care following eyelid laceration repair
Protective mask Triple antibacterial ointment q8h for 1-2wk Systemic NSAIDs (Banamine) +/- systemic abx
39
Consequences of improper eyelid repair
Corneal ulcer d/t suture rub Poor tear film retention or dispersion leading to chronic keratitis
40
CS of facial paresis/paralysis
Ptosis/diminished ability to blink Ear droop and diminished motility Nose deviation Flaccid lip/diminished function
41
Name some potential causes of facial paresis/paralysis
Trauma Inflammation of inner ear, guttural pouch, salivary gland Fracture of stylohyoid, petrous temporal bone, ramus of mandible
42
Why is lubrication of the cornea so important with facial paresis/paralysis?
Tears are being produced but aren’t able to be distributed Lubricant will cover the cornea and stick around for a bit Should be doing 4-6x/d
43
What can you do while waiting for eyelid function to be restored that will help prevent corneal ulcers?
Partial temporary tarsorrhaphy
44
______________ is the inflammation of palpebral and/or bulbar conjunctive; this condition is usually _________
Conjunctivitis; secondary
45
CS of conjunctivitis
Hyperemia Chemosis Ocular discharge
46
_________ is the most common neoplasm of horses
A sarcoid
47
Typical signalment associated with sarcoids
Young age (3-6y) Increased risk in QH, Appaloosas, Arabians
48
Prognosis of sarcoid
Metastasis is rare Recurrence is VERY COMMON
49
How do we treat sarcoids?
Surgical excision w/ adjunctive cryotherapy, hyperthermia, radiation Chemotherapy (intralesional/topical) Immunotherapy Others
50
You are examining a horse with a firm mass near its eyelid. You are highly suspicious of a sarcoid. You recommend excision to the owner. What could you have done better?
1. Unless sarcoids are compromising the eye, you should leave sarcoids alone. You don’t want to remove too much eyelid and they often recur. 2. Excision alone has a high rate of recurrence As long as the patient is clinically normal, don’t mess with it and continue to monitor. Typically, sarcoids are slow growing.
51
_________ is the most common neoplasm of the equine eye and ocular adnexa
SCC
52
What regions of the eye are most commonly affected by SCC?
TE and medial canthus Limbus Eyelid
53
T/F: Surgical excision for treatment of SCC is associated with recurrence rate of 50-60%
T: Need some form of adjunctive therapy Exception - TE removal is typically curative for TE SCC
54
Nasal lacrimal duct atresia is….
Imperforate nasal punctum Most common congenital nasolacrimal abnormality in foals
55
How can we diagnose NL duct atresia or imperforate nasal punctum?
Nasal punctum not visible Inability to flush NL duct Contrast radiography Culture/susceptibility (most have secondary bacterial dacryocystitis)
56
Treatment for imperforate nasal puncta
Create nasal punctum by passing catheter and cutting Prevent re-obstruction by leaving catheter in place for 4-6wk Treat secondary infection (dacryocystitis)
57
What is the role of the corneal endothelial cells?
Pump fluid out of cornea to prevent build up (corneal edema)
58
Dysfunction of endothelial cells or disruption of epithelium will lead to
Corneal edema Can’t pump fluid out or too much fluid being let in
59
Potential etiology behind ulcerative keratitis
Trauma FB Exposure/Paralytic keratitis EHV (uncommon to rare) KCS (rare)
60
3 major ulcer categories
Superficial Stromal (Superficial, mid, or deep stromal) Desmetocoele
61
Describe the appearance of a desmetocoele
Perfect clear lesion (basement membrane) in the middle of a cloudy lesion Loss of stroma and fluid can’t accumulate
62
What do we mean by “complicated” ulcers?
Secondary infection (bacterial, fungal) Stromal degradation Iridocyclitis (uveitis)
63
You come across an ulcerated cornea with snotty material that gets stuck to your cotton swab. What likely is this material?
Lytic corneal stromal collagen indicating a “melting” ulcer
64
What’s the best way to evaluate whether or not a corneal ulcer has healed?
Stain! If the cornea is no longer taking up stain, you can stop treatment
65
Define cycloplegia and what medication can we use to achieve this
Paralysis of the ciliary body to prevent spasm Atropine
66
CS of corneal perforation
Iris prolapsed/fibrin Corneal edema Hyphema/hypopyon
67
T/F: In most cases, corneal perforation can be managed conservatively
False - almost always a surgical disease
68
Describe the appearance of a corneal abscess
Yellow-white stromal opacity
69
Are corneal abscesses painful?
Yes and they are often accompanied by secondary uveitis
70
What is band keratopathy and what disease is it associated with?
Corneal mineralization/calcification ERU and chronic uveitis Typically non-painful unless ulceration occurs d/t sloughing mineral
71
T/F: IMMK is a very painful condition
False - typical non to minimally painful chronic disease
72
Clinical findings associated with eosinophilic keratoconjunctivitis
Ocular discomfort Raised pink-white necrotic corneal plaque Variable corneal ulceration
73
What is the best diagnostic tool for eosinophilic keratoconjunctivitis?
Cytology - will see eosinophils
74
What is the only kind of ulcer you should ever use steroids on?
Ulcers associated with eosinophilic keratoconjunctivitis
75
Describe the appearance of corneoconjunctival squamous cell carcinoma
Typically raised fleshy/verrucous appearance Usually lateral limbus
76
How can you differentiate corneoconjunctival SCC from stromal invasive SCC?
White stromal infiltrates present Not raised like typical superficial SCC
77
Treatment for corneoconjunctival SCC
Surgical excision Laser ablation Cryotherapy Photodynamic therapy Radiation therapy Topical chemotherapy

Eq Special Topics (3 decks)

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