4 - orbit

incomplete bony orbit in dog and cat

complete bony orbit in horse and ruminant

absolute enlargement of globe

secondary to chronic glaucoma

dx: measure corneal diameter/axis of globe w/ U/S

rostral displacement of globe

abnormal protrusion of globe

not associated with globe size

recession or retraction the globe into the orbit

± narrowing of palpebral fissure

involuntary deviation of globe from primary position

should include palpation of globe and periocular structures

digitally retropulse globe

examine oral cavity → resistance to opening mouth typical of retrobulbar abscess, oribtal cellulitis (don’t tx with cefovecin)

doesn’t usually have pain on opening the mouth

fever or leukocytosis absent

hard, painful masticatory muscles, atrophy

type II muscle fiber antibodies

tx: corticosteroids, azathioprine

acute onset of bilateral exophthalmos, chemosis

<1 yr, female

brachycephalic breeds

prognosis for vision: guarded to poor

tx: tarsorrhaphy (split thickness), lateral canthotomy

goal: pull lids over globe → DON’T force globe back in

prevention: medial canthoplasty → decrease eyelid opening

atrophy of globe due to interruption in blood supply

medial rectus most commonly ruptured muscle

damage to 3 or more extraocular muscles result in anterior segment necrosis → globe blood supply enters near extraocular muscles