Orbit Flashcards
Define buphthalmos.
Abnormal enlargement of the eyeball
Only caused by glaucoma
Size is abnormal, position is normal
Define enophthalmos.
Abnormal recession of the eye within the orbit
Define exophthalmos.
Abnormal protrusion of the eye from the orbit
Position is abnormal, globe size is normal
Define Horner’s syndrome.
Sympathetic denervation to the eye and ocular adnexa
What are the 4 classical clinical signs for Horner’s syndrome?
Enophthalmos
Ptosis
Miosis
Protrusion of the third eyelid
Define microphthalmos.
A congenitally small and malformed globe
Define phthisis bulbi.
An acquired shrunken globe, most often from severe or chronic inflammation
Define proptosis.
Anterior displacement of the globe such that the eyelids are caught behind the equator of the globe
Define strabismus.
Deviation of one or both eyes, so that both eyes are not directed at the same object
Which species have open orbits? Closed?
Open - dogs and cats
Closed - horses and ruminants
What are the commonly associated clinical signs with exophthalmos?
Third eyelid protrusion
Facial swelling
Soft palate bulging
Pain opening mouth
Fever
What is the most common cause of exophthalmos?
Orbital volume imbalance:
Orbital neoplasia - non painful
Orbital cellulitis/abscess - painful, working dogs, stick chewers
What must be included in medical management or orbital cellulitis/abscesses?
Anti-inflammatory therapy (NSAID or steroid) and antibiotic (broad spectrum - clavamox)
What should be kept in mind when doing an enucleation in a cat?
The optic chiasm can be affected by direct tension of the eye during enucleation
This can blind the normal/unaffected eye
What are the common clinical signs for enophthalmos?
Facial muscular loss (pred head)
Third eyelid protrusion
Entropion
What are the common causes of enophthalmos?
Dehydration
Emaciation or cachexia
Myopathies
Space occupying lesions anterior to the globe
Ocular pain
Horner’s syndrome
What are the common causes of stabismus?
Normal variation - brachycephalic
Convergent strabismus - siamese
Ventrolateral divergent strabismus - hydrocephalus
Mechanical or nervous dysfunction of any rectus muscle
Imbalance of orbital volume
What does CN 3 do?
Dorsal, ventral, medial rectus muscles and ventral oblique
What does CN 4 do?
Dorsal oblique
What does CN 6 do?
Retractor bulbi and lateral rectus
What is the #1 complication for tarsorrhaphy treatment in proptosis cases?
Corneal ulceration - mostly from misplaced sutures
