Dz and Sz of orbit (Whitley) Flashcards
1
Q
Orbit
A
- Cavity that holds the eye
- pyramid shaped cavity
- apex towards back of head
- contains
- globe
- related muscles
- blood supply
- nerve supply
- fat
- Carnivores: incomplete orbit
- lateral ligament
- dorsolateral portion: dense collagenous orbital ligament
- from zygomatic process of frontal bone to
- frontal process of zygomatic bone
- Herbivores/pigs: complete bony orbit
2
Q
Orbital Contents
A
- Bones
- Globe and optic nerve
- EOM in fascial slings
- Periorbita from orbital septum to tarsal plate
- Masticatory and pterygoid muscles
- Salivary and lacrimal glands
- many species with zygomatic salivary gland in orbit
3
Q
Floor of orbit
A
- soft tissue
- susceptible to penetrating trauma through the roof of the mouth
4
Q
Extraocular muscles
A
- Rectus muscles
- lateral
- medial
- dorsal
- ventral
- Oblique muscles
- superior/dorsal oblique
- ventral oblique
- Retractor bulbi
5
Q
DX tests for orbital dz
A
- Symmetry, d/c
- palpation, retropulsion
- attempt to open mouth
- pain: usually abscess
- exophth w/o pain: more consistent w/ neoplasia/cystic mass
- complete ophthalmic exam
- U/S, rads, CT, MR
- dental rads
- FNA
- BX (U/S guided)
- surgical explore
6
Q
Posterior indentation of globe seen w/
A
- Indirect ophthalmoscopy (BIO)
- Ocular ultrasound
- Transoral approach to ultrasound of orbit
7
Q
Clinical signs of orbital dz
A
- Globe displacement
- Periorbital swelling
- facial deform
- vis. impairment
- Imp nasal flow
- Ocular/oral pain
- pain when chewing
- Strabismus
- Chemosis
- protrusion of TE
- Blepharoedema
- Exposure keratitis
8
Q
Proptosis
A
- eyelids become entrapped behind the equator of the globe
- cannot blink
- globe usually anteriorly displaced
- secondary to trauma
- some cases will require enucleation
- TX
- lubricate
- assess for other trauma
- clean eye: eye wash, saline and dilute betadine
- lateral canthotomy
- strabismus hook pulls eyelids over globe
- temporary tarsorrhaphy (suture lids closed over globe
- horizontal mattress superficial sutures
- E-Collar
9
Q
Proptosis prognosis
A
- depends on
- condition of globe
- extend of orbital trauma
- PLRs
- size of pupil
- number of ruptured extraocular muscles
- 3 or greater not great prog
- duration
10
Q
Proptosis
Complications
A
- Loss of globe
- blindness
- strabismus
- corneal ulcers
- keratitis
- KCS
11
Q
Favorable prognosis for proptosis
A
- Brachycephalic breeds
- Intact PLR normal fundus
- No hyphema
- Only 1 EOM ruptured
12
Q
Poor prognosis for Proptosis
A
- Cats
- Non-brachycephalic breeds
- Hyphema
- No visible pupil
- orbital fractures
- more than 3 EOM torn
- damage to optic nerve
13
Q
Post Proptosis Exoptropia
A
- Lateral strabismus
- medial rectus often the muscle that is torn
14
Q
Proptosis prevention
A
- Medial or lateral canthoplasty
15
Q
Inflammation
A
- Retrobulbar abscess
- tooth root abscess
- Orbital cellulitis
- Immune-mediated myositis
16
Q
Retrobulbar abscess
CS
Labwork
A
- Acute onset, febrile
- Exopthalmos unilaterally
- Lymphadenomegaly
- Leukocytosis
- Reddened, discolored swelling posterior to last upper molar
- Pain on jaw manipulation
- Pain on retropulsion of eye
17
Q
Retrobulbar abscess
TX
A
- Establish drainage if possible
- culture and sensitivity
- Systemic abx
- Analgesia
- NSAIDS
- Supportive care for globe and cornea
- reoccurance search for
- neoplasia
- retained foreign body
- tooth root dz
18
Q
Sampling of retrobulbar space
A
- Blind or U/S guided
- Oral
- through roof of mouth behind last molar
- Incise mucosa with blade, then use blunt straight hemostats to enter and sample
- Be aware of maxillary artery
- Dorsolateral to lateral canthal ligament
- Transconjunctival
19
Q
Orbital neoplasia
A
- Slow onset
- Exophthalmos unilaterally
- minimal to no pain on palpation/manipulation
- Older patients
- Poor prognosis
- malignancy and late dx
20
Q
Common tumors
A
- fibrosarcs
- osteosarcs
- osteochondrosarcs
- meningioma
- lymphoma
- mastocytoma
- squamous cell carcinoma
21
Q
Neoplasia tx
A
- tx and px depends on type and extent
- surgical removal
- radiation and chemo adjunctive
22
Q
Bilateral extraocular polymyositis
A
- Immune-mediated condition
- Antibodies against EOM, type 1 myofiber autoantibodies
- neg for type 2 myofiber autoantibodies
- Bilateral big eye muscles
- predisposition
- young (<2yo) goldens
- young labs
- Histopath
- lymphocytes
- histiocytic macrophages
- TX
- prednisone
- cyclosporine
- azathioprine
- Recurrences common
23
Q
Masticatory Myositis
A
- Immune-mediated
- autoantibodies against type II (2) M myofibers
- usually bilateral
- Variable severity
- GSD more common
- CS
- exophthalmus
- pain opening mouth
- vision loss
- Tx
- prednisone
- azothioprine
- Recurrences common
24
Q
Orbital surgery
A
- Tarsorrhaphy
- suturing eyelids closed
- Enucleation
- removing globe
- Exenteration
- removing all structures associated with the eye
- Focal Lesion removal
- orbitotomy
25
Retrobulbar anesthesia
* Standard care for enucleations
* four point
* supraorbital fossa
* dog
* through lower eyelid
* lateral third
* lidocaine toxic at 8mg/kg
* bupivicaine preferred post op
* Anesthetics
* lidocaine
* bupivicaine
* carbocaine
* Cats: **calculate toxic dose first**
* ****lidocaine toxic at 2 mg/kg
* bupivicane preferred in cats
26
Enucleation
techniques
* Transpalpebral
* infections
* neoplasia
* Transconjunctival
* remove TE and conjunctiva
* Orbital implant
27
Orbitotomy
* Explore indicated to
* evaluate
* bx
* remove lesions behind globe
* performed to preserve vision and remove retrobulbar neoplasia
* several surgical approaches described
