Opthalmology

Question 1

Strabismus

Answer 1

Abnormal ocular globe position
– Bilateral hereditary condition – Secondary
• Orbital neoplasia, CN dysfunction from listeriosis or polioencephalomalacia

Question 2

Types of strabismus

Answer 2

– Divergent (exotropia) - a form of strabismus where the eyes are deviated outward.
– Convergent (esotropia) -a form of strabismus where the eyes are deviated inward.

Question 3

exophthalmos

Answer 3

abnormal protrusion of the eyeball or eyeballs.

Question 4

Nystagmus

Answer 4

Horizontal movement of the ocular globe

Question 5

Nystagmus - congenital & aquired signalment

Answer 5

– Hereditary congenital:
• Ayshires, Guernseys and Holsteins
– Acquired:
• Calves that develop dysfunction of their peripheral
vestibular system or cerebellum
• Following an ear infection or systemic disease

Question 6

Microphthalmia - what is it? causes? sequelae?

Answer 6

Congenitallysmalleyes
– Inherited or acquired 
     • BVD
– Unilateral or bilateral – Small ocular globe
     • Protrusion of third eyelid
– Ocular anomalies
     • Cataracts, retinal dysplasia

Question 7

Entropion

Answer 7

The inversion of eyelids – Neonatal cattle
– Secondary
• Systemic diseases
• Corneal ulcers – Lacrimation
– Bilateral:
• Result in visual deficits
• Impact on growth / weight gain

Question 8

Entropion - Treatment

Answer 8

– Temporary correction with placing vertical mattress sutures
– Permanent correction with the removal of a skin crescent with
wound closure
– Topical antibiotics + atropine if corneal ulcers present

Question 9

Dermoid

Answer 9

Ectopic skin cells
– Third eyelid, conjunctiva, cornea – Herefords:
• Genetically predisposed – Hair follicles, skin glands
– Epiphora
– Treatment:
• Surgical excision

Question 10

Infectious Bovine Keratoconjunctivitis (IBK) - pathogens that cause this:

Answer 10

– Moraxella bovis:
• Gram-negative bacillus
– Secondary pathogens:
• Mycoplasma and IBR

Question 11

Infectious Bovine Keratoconjunctivitis (IBK) - trasmission, signalment

Answer 11

– Transmission: flies
– Summer outbreaks
– Herefords, Hereford crosses, Murray Grays
• Highest susceptibility

Question 12

Infectious Bovine Keratoconjunctivitis (IBK) - clinical signs, progression

Answer 12

• Clinicalsigns: – Initial stages:
• Hyperemic conjunctiva • Blephrospasms
• Serous discharge
– Progression:
• Mucopurulent discharge
• Corneal edema, ulceration, neovascularization • Corneal perforation
– Secondary uveitis is also commonly seen

Question 13

Infectious Bovine Keratoconjunctivitis (IBK) - treatment

Answer 13

– Controlling the fly population
– Isolating affected cattle
– IM long-lasting tetracycline repeated
in 72 hours
   • Topical tetracycline (TID)
   • Topical atropine (BID)
– Corneal rupture:
   • Conjunctival flaps or enucleation
– Vaccination: controversial

Question 14

IBR

Answer 14

– Ocular and respiratory disease
– Mimics IBK clinical signs – Diagnosis:
• Viral cultures or paired serum samples for titers
– Treatment:
• Controlling secondary bacterial infections with topical antibiotic ointment
– Prevention:
• Vaccinations

Question 15

Uveitis

Answer 15

Septicemia, endotoxemia, navel ill (calves)
• Listeriamonocytogenesinfection
– Secondary to feeding of big-bale silage
• Haemophilussomnus(infectiousthromboembolic meningoencephalitis)
– Conjunctival and episcleral hyperemia, miosis, aqueous flare, hypopyon, vitritis, retinal hemorrhages
– Anti-inflammatory drugs (topical and systemic)
– Topical atropine
– Systemic antibiotics

Question 16

Hyphema: causes

Answer 16

Uveitis or trauma

Question 17

Malignant Catarrhal Fever: signalment, clinical signs, diagnosis

Answer 17

Cattle,llamas,deer,bison 
– Herpes virus
– Clinical signs:
     • Lacrimation, serous to mucopurulent ocular discharge, episcleral and conjunctival hyperemia, severe corneal edema, miosis, hypopyon and iritis
– Diagnosis:
     • Histopathology
– Treatment:
     • High mortality rate
– Related to progression of uveitis

Question 18

Cataracts: Types, signalment, treatment

Answer 18

Congenital, genetic or acquired – Genetic:
• Herefords, Holsteins and Jerseys – Acquired:
• BVD can be transmitted from the mother in the early to mid stages of the pregnancy
• Anterior uveitis
– Treatment:
– Monitor
– Cataract surgery

Question 19

Blindness: Causes, types, diagnosis, treatment

Answer 19

• Vitamin A deficiency – Night blindness
• Followed by day blindness
– Bone growth at the optic foramen
• Results in a constriction of optic nerve – Diagnosis:
• Serum levels <25mg/dl – Treatment:
• Vitamin A supplementation
KN Gelatt. Color Atlas of Veterinary Ophthalmology

Question 20

Retinal degeneration

Answer 20

• Ingestionof: – Cattle:
• Male fern (Dryopteris felix mas) – Sheep/goats:
• Blind grass (Stypandra glauca) – Blindness
• Optic nerve atrophy
• Neuropathy – No antidote
KN Gelatt. Color Atlas of Veterinary Ophthalmology


Question 21

Squamous Cell Carcinoma *** Exam

Answer 21

• Mostcommonoculartumour
• Hereford:predilection
– Ultraviolet light and absence of periocular pigment are
predisposing factors to developing tumors
• Lesions have the potential to regress or to develop into a malignant tumor

Question 22

Squamous Cell Carcinoma *** Originates

Answer 22

• Eyelid margin, palpebral conjunctiva, third eyelid, limbus or cornea
• Lesions are usually broad based and vascular with an irregular cobbled-stone appearance.
– Rapidly growing lesions may also ulcerate and have necrotic tissue.

Question 23

Squamous Cell Carcinoma *** Treatment

Answer 23

– Surgical excision with large margins
• Exenteration of the orbital contents – Adjunctive therapy:
• Cryotherapy – Metastasis
• Regional lymph nodes

Question 24

Papillomas: what is it? treatment?

Answer 24

– Pedunculated with a cauliflower
appearance
– Margin of the third eyelid – Similar appearance to SCC 
– Treatment
• Surgical excision 
• Tend not to recur

Question 25

Lymphoma: what is it? lined to?

Answer 25

• Retrobulbarmass
– Exophthalmia +/- strabismus
– Unilaterally or bilaterally
– Exposure keratitis
– Severe cases: visual impairment and blindness
• Linked:bovineleukemiavirus (BLV)
– Approximately 5% of BLV positive cows develop lymphosarcoma

Question 26

Lymphoma: diagnosis, treatment, prevention

Answer 26

• Diagnosis
 – Cytology or histopathology
• Treatment:
– Palliative third eyelid flap
• Prevention: – BLV testing
– Prompt isolation
– Control of blood sucking insects

Question 27

Camelid Ocular Diseases: Congenital nasolacrimal duct disorders - name 3 types, treatment?

Answer 27

– Atresia of duct or puncta
– Epiphora
– Dacryocystogram
– Create opening with incision through imperforated mucosa; Leave tubing in for 6 weeks

Question 28

Camelid ocular diseases

Answer 28

Conjunctivitis
– Usually secondary to corneal ulcer, uveitis, environment
– Primary infection: chlamydiae, thelazia
– Dilation of conjunctival blood vessels
– Treat underlying cause

Question 29

Camelid ocular diseases - corneal ulceration

Answer 29

– Similar to other species: simple, indolent, complex – Topical antibiotics in all cases
– Topical atropine if miosis
– Grid keratotomy if indolent
– Serum if melting


Question 30

Camelid ocular diseases: Corneal abscess

Answer 30

– Similar to horses
• Intact epithelium • Bacterial or fungal
– Topical bactericidal antibiotics
– Topical anti-fungal
• If no response
• If seen deep within corneal stroma

Question 31

Camelid ocular diseases: Cataracts: what are they? how can it be caused? treatment?

Answer 31

– Opacity of the lens
– Visual impairement?
– Lens induced uveitis – Monitor or surgery

Question 32

Camelid ocular diseases: Uveitis: types, work-up, treatment

Answer 32

– Primary
• Infectious
– Septicemia
– EHV, Toxo, Aspergillosis • Trauma
– Secondary
• Corneal ulcer, cataract
– Work-up
• PE, blood tests
– Anti-inflammatory therapy

Question 33

Camelid ocular diseases: Intraocular neoplasia, name 3 types

Answer 33

– Medulloepithelioma
– Retinoblastoma
– melanoma