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Ch.39Eye Flashcards

1
Q

Although tear deficiencies are uncommon in large animals, what is the normal Schirmer tear test?

A

**can check in 30 seconds

> 20mm is normal

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2
Q

define micropapilla

A

hypoplasia of the optic disk

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3
Q

define pappilledema

A

elevation of the optic disk

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4
Q

define cupping of the optic disk

A

depression

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5
Q

What are the layers of the cornea

A

1.epithelium
2. Bowmans layer
3. Stroma
4. Descemets membrane
5. Endothelium

**first 3 layers uptake stain

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6
Q

Congenital strabismus is reported in what breeds of cattle

A

Jersey
shorthorn
Holstein
German Brown Swiss cattle

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7
Q

Causes of enophthalmos

A

dehydration
loss of retrobulbar fat and/or muscle
congenitally shallow orbit
sympathetic denervation
pain and assoc retraction of globe
microphthalmos
globe rupture

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8
Q

Causes of Exophthalmos

A

Trauma: hemorrhage, tissue swelling
orbital neoplasia
inflammatory orbital lesion: foreign body, cellulites, abscess, granuloma, cyst, CN VI lesion (loss of retractor bulbi)

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9
Q

Causes of microphthalmos

A

viral: bovine viral diarrhea (BVD)
Genetic:
Teratogenic

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10
Q

define anisocoria

A

pupillary asymmetry

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11
Q

Differentials for anisocria

A

1.primary iridal lesions
2. Neurologic disorders (horners syndrome, oculomotor n dysf)
3. Intraocular dz (uveitis, glaucoma, etc)
4. Dzs involving optic nerve or brain stem
5. Previous use of pharmacologic agents (atropine)

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12
Q

ocular squamous cell carcinomas commonly arise from

A

nonpigmented tissues of:
-nictating membrane
-lateral limbal region
-eyelid margin

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13
Q

Suspected pathogenesis of damage to optic nerve

A

1.shearing forces at optic foramen from displacement of the brain after severe head trauma
2. direct contusion or avulsion of the optic nerve
3. loss of blood supply to the nerve and subarachnoid hemorrhage

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14
Q

Traumatic optic nerve atrophy is characterized by:

A

1.onset of uniltaeral or bilateral blindness
2. dilated fixed pupils
3. lack of menace repsonse

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15
Q

What are delayed clinical findings in a traumatic optic nerve blindness

A
  • w/in 3 to 4 weeks of trauma, examinatin of fundus revealed a pale optic disk
  • loss of peripapillary retinal vessels
    -depression of optic disk– inc prominence of hte lamina cribrosa
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16
Q

How does acetylcysteine work as a collagenase inhibitor?

A

binds calcium– inhibiting collagenases and metalloproteinases

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17
Q

Define uveitis

A

inflammation of the uveal tract

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18
Q

What structures are included in the uveal tract?

A

iris
ciliary body
choroid

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19
Q

What isolates commonly cause keratoconjunctivitis in goats and sheep?

A

Mycoplasma conjunctivae- goats and sheep
Mycoplasma mycoides subsp mycoides- goats
Acholeplasma oculusi (oculi)- sheep and goats
Mycoplasma agalactiae and arginini

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20
Q

Differential diagnosis for Mycoplasma keratoconjunctivitis

A

-Chlamydophila spp (sheep)
-Branhamella spp.
aerobic bacteria
parasites
infectious bovine rhinotracheitis (goats)
noninfectious causes (trauma)

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21
Q

Diagnosis of Mycoplasma keratoconjunctivitis: what is seen on conjunctival scrapings

A

–>neutrophils, later lymphocytes
–plasma cells and necrotic epithelial cells
–organisms found in epithelial cell cytoplasm in coccobacillary or varied forms

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22
Q

If Mycoplasma conjunctivae is cultured from goat with keratoconjunctivitis, does that mean it is causing disease?

A

No, a subclinical carrier states exist

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23
Q

Treatment recommendation for Mycoplasma keratoconjunctivitis?

A

-recover spontaneously in 10 days
- some may have recurring episodes that last several weeks

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24
Q

Most lambs that develop keratoconjunctivitis with this bacterial agent, will also develop polyarthritis

A

chlamydia pecorum

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25
Treatment of Clamydia pecorum keratoconjunctivitis cases
-usually resolve on own in 2 to 3 weeks
26
Bacterial keratitis in horses-- what bacteria can cause ulcers?
no bacteria are known to initiate corneal ulcers in horses-- all opportunistic bacteria
27
Examples of bacteria that can be normally cultured from the equine eye:
Corynebacterium Streptococcus Staphylococcus Bacillus rarely Pseudonomas spp other gram neg bacteria
28
rods/ Gram negative organisms seen on corneal cytology, which antibiotics should be used
bacitracin-neomycin- polymixin B aminoglycoside antibiotics (gentamicin, tobramycin) fluoroquinolones (ciprofloxacin, ofloxacin)
29
cocci/gram positive organisms seen on corneal cytology, which antibiotics should be used
bacitracin-meonycin polymyxin B neomycin polymixin B-gramicidin chloramphenicol levofloxacin cefazolin penicillin or ampicillin
30
What are the most common fungal organisms cultured from equine cornea?
Aspergillus and Fusarium spp **many other spp of other genera also have bene cultured
31
Natamycin may be used as a topical antifungal, however what is its caveat? and what is a good alternative?
It does not penetrate intact cornea voriconazole-- penetrates an intact cornea
32
What is a good drug to use when yeast is causing a fungal keratitis?
amphotericin B-- howver it is irritating to the eye
33
Viral agents in horses that cause keratitis?
EHV-2 and -5
34
Besides ocular disease (conjunctivitis), what other manifestations of disease will occur with BHV-1
upper respiratory tract signs: rhinitis, dyspnea, pyrexia, dec in milk yield abortion
35
BHV-1 conjunctivitis results in lymphoid hyperplasia, which is visible as
white plaques
36
Prion proteins of scrapie can be found in what ocular structure and may allow antemortem diagnosis of scrapie?
nictitating membrane
37
What is the most common orbital neoplasia in cattle?
bovine lymphosarcoma -- unilat or bilat exopthalmos
38
Differential considerations for progressive exopthalmos in cattle include:
bovine lymphosarcoma (orbital) orbital cellulitis (actinomycosis or actinobacillosis) frontal or maxillary sinusitis nasal or orbital neoplasia (SCC)
39
Tuberculosis in cattle caused by Mycobacterium bovis may cause what lesions in affected eyes?
granulomatous lesions of uveal tract (initially)
40
What are clinical signs of infectious Bovine keratoconjunctivitis (IBK)?
corneal ulceration corneal edema photophobia blepharospasm lacrimation
41
Is there a genetic association with formation of infectious bovine keratoconjuncitivitis?
yes --hereford fresian cross bred calves with full eyelid pigmentation had lower incidence of IBK vs calves with less than total pigmentation -5 signal nucleotide polymorphisms on bovine chromosome 20 that are significantly assoc with IBK have also been identified
42
What bacteria has been associated with infectious bovine keratoconjunctivitis?
Moraxella bovis --other agents: infectious bovine rhinotracheitis (IBR) virus and mycoplasma spp
43
What are risk factors for infectious bovine keratoconjunctivitis?
flies solar irradiation mechanical trauma form plant awns
44
What has been shown to reduce infectious bovine keratoconjunctivitis within a herd?
insecticide-impregnate ear tags or back and face rubbers to reduce fly populations
45
What is the difference between pathogenic and nonpathogenic moraxella bovis?
pathogenic- hemolytic nonpathogenic-non-hemolytic
46
What are the 2 major the Moraxella bovis proteins that have been linked to its pathogenicity?
pili-- (type IV, N-methylphenylalanine type) allows bacteria to adhere to corneal epithelium cytotoxin
47
Moraxella bovis cytotoxin plays what role in its pathogenecity?
pore-forming protein -- lytic activity is calcium depedent formation of transmembrane pores in target cell membranes
48
Moraxella bovis is susceptible to what antibiotics?
penicillin-subconjunctively parenterla oxyttetracycline florfenicol IM/SC tulathromycin Ceftiofure CFA
49
Type 1 hypersensitivity is manifested in the eye as
conjunctivitis-- IgE mediated mast cell inflammatory increase in vascular permeability, constrict smooth mm, dilate blood vessels and activate luekocyte chemotaxis and complement cascade
50
Type II hypersensitivity (cytotoxic/cytolytic) has what 2 basic effector pathways that lead to cell destruction?
1. opsonization, with INC efficiency of phagocytic destruction 2. ab-dependent cellular cytotoxicity, inducing the release of enzymes capable of destroying cells and digesting basement membranes 3. lysis of immunoglobulin bearing cells
51
Type III (immune complex) hypersensitivity may be associated with clinical signs seen in which diseases?
-pemphigus foliaceus -post vaccine influenza-- intraocular inflamm -uveitis (implicated)
52
Diagnosis of allergic blepharoconjunctivitis is often presumptive, and elimination of other causes such as:
-trauma -orbital inflammation -neoplasia -mechanical irritants -conjunctival parasites -other infectious agents (ocular and systemic)
53
In support of allergic etiology to blepheroconjunctivitis, what would be seenon cytology
eosinophils
54
What are ocular manifestations of pemphigus?
ulceration or crusting of eyelids mucoid ocular discharge conjunctival hyperemia with erosions
55
What is diagnostic of eosinophilic keratoconjunctivitis on cytology?
eosinophils
56
What is the believed mechanism of eosinophilic keratitis ?
toxic effect of eosinophilic major basic protein on the corneal epithelium leading to chronic corneal ulceration
57
Ceterizine (zyrtec) may be beneficial for use in treatment of eosinophilic keratitis for what mechanism?
H1 antagonist that may be useful in decreasing the migration and adherence of eosinophils
58
What treatments decrease the duration of eosinophilic keratitis?
oral steroids -tx with oral ceterizine does not decrease treatment time, but were less likely to have recurrence
59
Superficial keratectomy in the treatment of eosinophilic keratitis will enhance healing time because
removal of the eosinophil-granule major basic protein
60
Although the stimulating antigen is unknown, what is the underlying immunological mechanism for ERU?
-delayed hypersensitivity reaction -recurrent inflammatory episodes
61
Describe Chorioretinal scars, commonly referred to as peripapillary "butterfly" lesions and what disease they are associated with
multifocal depigmented or hyperpigmented foci on either side of the optic disk sequalae of chorioretinitis ERU
62
Chronic recurrent uveitis is characterized by:
widespread posterior synechiae iris depigmentation or hyperpigmentation iris atrophy
63
Findings on ocular exam that are indicators of inflmamation that should be observed before a presumptive diagnosis of ERU
corneal edema or vascularization synechiae (typically posterior) iris color change corpora nigra atrophy or "polishing" lens capsular pigmentation cataract lens luxation or subluxation vitreious opacities or traction bands retinal detachment peripapillary scarring
64
What breed is more likely to develop ERU?
Appaloosa
65
ocular disease caused by Onchocerca cervicalis is a result of
aberrant migration of noninfective microfilariae into the palpebral, conjunctival and corneal tissues
66
ocular onchocerciasis occurs mostly in what age group?
adult horses
67
Definitive diagnosis of onchocerca keratoconjunctivitis is made via
corneal or conjunctival biopsy
68
onchocerca corneal lesions:
-wedge shaped-- base of triangle at the limbus characterized by varying degrees of superficial and deep neovascularization and cellular stromal infiltrates
69
Equine ocular habronemiasis occurs when larvae from what spp are deposited on ocular tissues?
Habronema muscae Habronema microstoma Draschia megastomas
70
Diagnosis of equine ocular habronemiasis?
demonstration of larvae in the granulomatou slesions or fistulous tracts
71
What is the treatment of choice for habronemiasis?
oral ivermectin or modixdectin-- kills both adults and larvae in teh stomach
72
What parasite in the conjunctival sac of large animals are considered commensal but can cause clinical ocular idsease?
Thelazia spp nematodes
73
Ocular thelaziasis treatment
flushing/manual removal from nasolacrimal duct -->ivermectin or doramectin-- cattle
74
"sore head" is a disease of sheep that is caused by what nematode?
Elaeophora schenideri
75
How do sheep develop sore head or ocular elaeophoriasis?
1. microfilariae produced and migrate into the capillaries of the face and head of deer 2. biting flies (Hybomitra and tabanus) transmit the microfliariae to new hosts
76
ocular Elaeophoriasis is seen in sheep in what area of the United States?
Western US where sheep are grazed at high altitudes
77
What is the most common intraocular parasite in horses and donkeys?
Setaria -- other filarides found free in anterior chamber include Dirofilaria immitis and O. cervicalis
78
What is the most economically important neoplasm of cattole?
bovine ocular squamous cell carcinoma "cancer eye"
79
What is the economic impact of bovine ocular squamous cell carcinoma?
carcass condemnations production losses treatment expenditures management costs
80
What is the difference in appearance of malignent vs pre-malignant bovine ocular squamous cell carcinoma?
pre-malignant: sm, white, superficial and elevated hyperplastic plaques or papilloma-like structures with verrucous surfaces malignant: irregular, nodular, pink, erosive, invasive in nature, accomanying necrosis, foul odor
81
Differentials for bovine ocular squamous cell carcinoma
conjunctival follicular hyperplasia dermoid fibroma fibrosarcoma granulation tissue infectious bovine keratoconjunctivitis lymphosarcoma mastocytoma
82
Although ocular squamous cell carcinoma has been reported ina wide variety of cattle breeds, what breed i smost often diagnosed and why?
Hereford breed -- result of common use of breed as a range animala nd strong genetic trait for a white face
83
Differentials for ocular SCC in the horse
adenocarcinoma adenoma angiosarcoma basal cell tumor conjunctival follicular hyperplasia dermoid fibroma fibrosarcoma grnaulation tissue habronemiasis lymphosarcoma mastocytoma plasma cell tumors sarcoid sschwannoma
84
Treatments for ocular SCC in horses
-excsision of corneolimba or corneal SCC via keratectomy with adjunctive therapy: radiation therapy cryonecrosis (liquid nitrogen) radiofrequency hyperthermia intralesional cisplatin or carboplatin
85
What is the most common neoplasm of dairy cattle?
bovine lymphosarcoma
86
Equine lymphosarcoma is usually a manifestation of
multicentric lymphoma
87
What is the second most common eyelid tumour of horses?
-sarcoids
88
What has been detected in association with equine sarcoidosis?
bovine papillomavirus (BPV-1 and BPV-2)
89
What breeds are predisposed to development of sarcoids?
Highest risk: Quarter horses Appaloosas Arabians

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