Unit 1 - Ophthalmology Flashcards
What are the normal components of the ruminant eye anatomy?
Upper and lower lacrimal puncta, horizontal pupil, dorsal and ventral papillary ruff, tapetum with ‘stars of winslow’ and holangiotic fundus
What are the normal components of camelid eye anatomy?
They are like ruminants but they are atapetal
What are the normal components of the swine eye anatomy?
Upper lacrimal punctum, round pupil when dilated, atapetal, and holangiotic fundus
What is microphthalmia?
Born with an abnormally small globe
What are the potential causes of microphthalmia?
Infectious, toxic, nutritional, environmental, or inherited factors could all be a cause
What teratogenic agents cause congenital eye conditions?
Veratrum californicum, bovine viral diarrhea virus, and bluetongue virus
What does Veratrum californicum cause and in what species?
Cyclopia (if ingested at 14 days of gestation) in lambs
What ocular defects can BVD cause?
Blindness, nystagmus, microphthalmos, corneal lesions, PPMs, cataracts, retinal dysplasia, chorioretinitis/retinal degeneration, and optic atrophy
What can Bluetongue virus cause and in what species?
Blindness, chorioretinitis, and retinal dysplasia in lambs
What congenital defects can occur to cattle nasolacrimal systems?
Supernumerary openings
What congenital conditions can camelids get in their nasolacrimal system?
Duct or punctal atresia
What is a dermoid?
A congenital plaque of differentiated skin in an abnormal location
Where are dermoids most commonly found in large animals?
Temporal limbus
What is the treatment of a small, hair-free dermoid?
None
What is the treatment of a painful dermoid or a dermoid that impairs vision?
Superficial keratectomy
What is entropion?
Eyelid inversion
What sequela can happen due to skin/hairs irritating the eye in patients with entropion?
Squinting and tearing, corneal ulceration, or blindness
What lid is commonly affected by entropion in large animals?
the lower lid
What species is entropion common in? How is it spread?
Sheep - congenital or early onset
How is entropion treated in young animals?
Temporary eversion
What are the methods of temporary eversion in entropion?
Vertical mattress tacking sutures
Metal clips or skin staples
Eyelid injection
How is entropion treated in mature animals?
Surgical correction - Hotz-Celsus or other techniques
What will the conjunctiva look like in a patient that is icteric?
yellow
What will the conjunctiva look like in a patient that is anemic?
white
What will the conjunctiva look like in a patient that has hypoproteinemia?
Billowy - it will be edematous and swollen
What will the conjunctiva look like in a patient that has thrombocytopenia, coagulopathies, or septicemia?
It will be petechiated
What clinical signs are associated with infectious bovine rhinotracheitis (IBR)?
Ocular signs +/- respiratory disease
What ocular findings will you see with IBR?
Conjunctivitis with serous to mucopurulent discharge
White conjunctival plaques
Keratitis +/- anterior uveitis
What disease may IBR occur concurrently with?
Infectious bovine keratoconjunctivitis (IBK)
What is the disease course of IBR?
2-4 weeks
What is the causative agent of IBK?
Moraxella bovis
How is Moraxella bovis transmitted?
contact, handlers, formites, and face fly vectors
What are the contributing factors to IBK development?
UV radiation, dry environment, shipping stress, and face flies
What breeds are more susceptible to IBK?
Bos taurus breeds
What breeds of cattle most commonly get IBK?
Herefords and Hereford crosses
Do old or young cattle get IBK more commonly?
Young
How does IBK originally present?
An acute disease which spreads rapidly
What season has the highest incidence of IBK?
Summer
Why do cases of IBK decrease in the fall?
Less susceptible calves, fewer vectors, and less enhancing factors
What clinical findings are associated with IBK?
It is unilateral or bilateral
Mucopurulent exudate, conjunctivitis, central corneal lesion (ulcer), corneal vascularization +/- granulation tissue, secondary uveitis, and corneal rupture if continued active ulceration
How does IBK cause economic loss?
The affected animals become anorexic due to pain +/- blindness
True or False: IBK is self-limiting
True - for 4-6 weeks
How is IBK treated?
Minimize production losses, cover affected eyes, antibiotics, and medications for uveitis
How do you minimize production losses in cases of IBK?
Prevent the spread, reduce the exposure to enhancing factors, shorten the course of disease with antibiotic treatment, and alleviate pain with atropine and systemic NSAIDs
How can you cover the IBK affected eyes?
Pinkeye patch, third eyelid flap, or temporary tarsorrhaphy
What does covering the eye in IBK patients not treat?
healing of the ulcer
What labled systemic antibiotics could be used for IBK?
Oxytetracycline (LA-200) and Tulathromycin (Draxxin)
True or False: Steroids should be added to treatment of IBK
False
What should be used for reflex uveitis in IBK spaces?
topical atropine or systemic flunixin meglumine
What management strategies can be used for prevention of IBK?
Fly control, temporary isolation of new animals, provide shaded areas, prior vaccination against IBR, and M. bovis bacterins
What causative agents cause infectious ovine/caprine keratoconjunctivitis?
Chlamydia and Mycoplasma spp. +/- others
What may exacerbate infectious ovine/caprine keratoconjunctivitis?
UV light
What ocular lesions are associated with infectious ovine/caprine keratoconjunctivitis?
The same that are associated with IBR and IBK in cattle
How is infectious ovine/caprine keratoconjunctivitis treated?
Isolate and let it run its course or treat with topical or systemic oxytetracycline
How are camelid corneal ulcers managed?
Like companion animal ulcers are, not cattle
What is ocular squamous cell carcinoma (OSCC) associated with in the eye?
periocular depigmentation
What are some risk factors for OSCC formation?
UV radiation, age (older), and genetic predilection (Herefords)
What clinical findings are associated with OSCC?
Pink to red lesions that are unilateral or bilateral
Any ocular or periocular location
Precursor lesions
Possible metastasis
What are the precursor lesions for OSCC?
Hyperplastic plaque, papulloma, noninvasive carcinoma, and keratoma
How is OSCC diagnosed?
Appearance, cytology, and biopsy
What are the most common treatments for OSCC?
Surgical excision, cryotherapy, enucleation/exenteration, or Euthanasia/slaughter
What other disease process is uveitis common with?
septicemia
What septicemic conditions in neonates can cause uveitis?
Umbilical infection, pneumonia, scours, etc.
What septicemic conditions in adults can cause uveitis?
Severe mastitis, metritis, and reticuloperitonitis
What clinical signs are associated with uveitis?
Pain, photophobia, hypopyon, miosis, swollen iris, peripheral corneal edema and vessels
What secondary changes are associated with uveitis?
glaucoma, cataract, and phthisis bulbi
How is uveitis treated?
Topical steroids, topical atropine, flunixin meglumine
Address underlying cause if known
Malignant Catarrhal Fever is an (acute/chronic) disease with (low/high) mortality.
acute, low
How does the head and eye form of Malignant Catarrhal Fever present?
Anterior uveitis and corneal edema
What indicates a poor prognosis in the head and eye form of malignant catarrhal fever?
Progression of edema and lack of uveitis improvement
What can cause cataracts in large animals?
Congenital and genetic, nutrition, or secondary to inflammation, toxins, and metabolic disease
What are cataracts a sequelae to?
anterior uveitis and trauma
What can cause blindness in large animals?
Optical axis impediments, retinal or optic nerve disease, and cortical blindness
What can cause retinal or optic nerve blindness?
Congenital conditions, infectious diseases, toxins, or deficiencies
What can cause cortical blindness in large animals?
Polioencephalomalacia and lead toxicity
What causes ocular cellulitis/abscess in large animals?
Trauma, foreign-body migration, infection, or chronic frontal sinusitis in cattle
What does cellulitis/abscess of the eye result in?
exophthalmos
How is ocular cellulitis/abscess treated?
Treat the underlying cause, drain abscess, and antibiotics
What is the most common bovine ocular neoplasia?
lymphosarcoma
What ocular surgeries are common in cattle?
Enucleation and exenteration for neoplasia
What nerve blocks can be done for ocular surgeries?
Auricular palpebral nerve block, local lidocaine block, or a four-point block
What does the auriculopalpebral nerve block cause to the eyelid?
akinesia
How is the auriculopalpebral nerve block done?
Inject lidocaine SQ where the nerve crosses the zygomatic arch (5-7 cm caudal to supraorbital process)
What is the local lidocaine block used for?
eyelid anesthesia during surgery
When is the four-point block used in cattle?
for enucleatuion
How is the four-point block done?
Insert 6 cm needle transconjunctivally adjacent to the globe dorsal, medial, ventral, and lateral
inject 5-10 mLs of lidocaine at each spot
What is the big concern and the main reason the peterson nerve block is not done?
It can cause apnea and then death if injected into the vessel or nerve sheath
