OPTHALMOLOGY 1 Flashcards
Is the canine orbit open or closed? What does that mean?
open: Incomplete in the
temporal or dorsal
region, continuous with the
temporal fossa
The canine orbit is divided into the intraconal and extraconal space. What is in the intraconal space?
extraocular muscles, CNII, III, IV, V(1), VI)
The canine orbit is divided into the intraconal and extraconal space. What is in the extraconal space?
neurovascular structures, nictitating membrane, zygomatic salivary gland
What is exophthalmos?
Protrusion of a normal-sized globe.
[really need to look from above the dog to see]
What are the clinical signs of orbital disease?
*Exophthalmos,
*increased resistance to digital retropulsion,
*strabismus,
*pain when opening the mouth, *third eyelid protrusion,
*periocular swelling, *lagophthalmos,
exposure keratopathy, *conjunctival hyperemia, chemosis, congestion.
What si strabismus?
eye going in a different direction
What are common causes of exophthalmos?
- Retrobulbar cellulitis/abscess
- Retrobulbar neoplasia
What are less common causes of exophthalmos?
- Myositis of masticatory or extraocular muscles
- Adenitis of the zygomatic salivary gland (sialoadenitis)
*Retrobulbar haemorrhage - Cystic space occupying lesions of the nictitans gland or zygomatic mucocoele
- Dacryops
- Dermoid cyst
What is lagopthalamos?
inability to blink/close eyes
What is dacryops?
fluid-filled cyst in lacrimal gland
where will a retrobulbular abscess be located?
periorbital space:
-peridontal/endodontal
-sinusitis
-sialoadenitis
-panopthalmitis
What are the 3 different aetiologies of retrobulbar abscess/cellulitis?
infectious or inflammatory:
*contagious periorbital structures/spaces
*direct inoculation/infection
*secondary orbital foreign bodies
these are clinical signs of what?:
*Acute presentation/rapid progression
*pain when opening the mouth,
* pyrexia, anorexia, neutrophilia with left shift
retrobullbular cellulitis
What are 4 diagnostic techniques for retrobulbar abscess/cellulitis?
*investigation
*orbital ultrasonography
*radiographs:
*examination of oral cavity
During diagnosis for retrobulbar cellulitis/abscess, what are you looking for during radigraphy?
during examination of the oral cavity?
rads: caudal maxillary molar tooth to assess for peridontal disease
oral cavity: pterygopalatine fossa n maxillary molar teeth
What initial management should be provided for retrobulbar cellulitis/abscess without an abscess or foreign body?
Broad-spectrum antibiotics (4 weeks) and NSAIDs.
[can do amoxy-clav or cephalosporins]
Why are retrobulbular abscess/cellulitis treated as an emergency?
direct communication btwn orbit and CNS
[optic nerve is surrounded by meninges]
What is the prognosis for retrobulbar abscess with proper treatment?
Generally good with proper antibiotic therapy and drainage.
What are the signs of retrobulbar neoplasia in dogs?
*Slowly progressive
*painless exophthalmos, *strabismus,
* third eyelid protrusion w/o pain with mouth opening or palpation.
What percentage of retrobulbular neoplasia are malignant?
90%
Retrobulbular neoplasia generally affects which age group?
> 8 y/o
What si the most common tpye fo retrobulbular neoplasia?
retrobulbular adenocarcinoma
In an exam for retrobulbular neoplasia, air flow should be examined where?
air flow in the nostril of affected side
What is the mean age of dogs affected by masticatory myositis?
3 years.
What is Masticatory myositis?
casued by damage to whcih muscles?
bilateral expothalamos due to swelling of temporal and pterygoid muscles
What is trismus?
inability/difficulty in opening mouth
What are some signs of Masticatory myositis
Trismus with signs of pain when attempting to open
the mouth OR when pressure is
applied over the temporal is or
masseter muscles.
acute fever, anorexia
prominence of zygomatic arch
What is the blood/internal clinical signs of masticatory myositis?
what is bilateral extraocular polymyositis?
how is this type of expothalamos unique?
tx?
expothalamos OU but no third eyelid protrusion
swollen extrocular mm
responds to corticosteroids
breed susceptibility to bilateral extraocular polymyositis?
young golden retriever & lab
What are the signs of traumatic proptosis?
Protrusion of the globe with eyelids trapped behind equator of the eye
What are positive prognostic signs for vision after traumatic proptosis?
- Brachycephalics
- Intact direct or indirect pupillary light reflex.
What are the negative prognostic signs for vision after traumatic proptosis?
- Cats (poor prognosis)
- Severe intraocular trauma
- Multiple extraocular muscle rupture
- Optic nerve damage
describe the steps to the replacement SX of a proptosed globe due to trauma
*GA, remove debris and flush ocular surface.
*check for ulcers with fluorescein. final flush
*lateral canthotomy to release tension of eyelids
*pass suture through upper eyelid 5mm from lid margin
*direct needle through meibomian gland on opposite lid 5mm from lid margin
*tarrsorhapy sutures eyelids shut for 14 days (small gap open at medial canthus for meds)
What is a species consideration in CATS for an eneucleation?
short optic nerve
What is a species consideration in RABBITS for an eneucleation?
large orbital venous sinus
What are the steps to a transpalpebral enucleation?
*eyelids held together with alis forceps/sutures
*cut the lateral canthal tendon
*section rectus and oblique muscles as close to the globe insertion as possible
*rotate globe medially to expose–>section retractor bulbi muscles and optic nerve WITHOUT clamping them first
*remove all conjuctival tissues
*close subcuticular layer
*close skin
What is enopthalamos?
Ocular pain causing globe retraction
What does the adnexa consist of?
external & third eyelid, conjuctiva, lacrimal system, orbit
What is a caruncle?
small pink nodule at medial canthus
Which is longer: medial or lateral canthal tendon?
lateral
Which muscle and cranial nerve closes the eye?
orbicularis oculi
CnVII
which anaesthetic eye drop can be used in exams for NUMBING?
proxymetacaine
What is distichiasis?
Abnormal cilia from meibomian gland openings.
What is ectopic cilia?
cilia emerges through conjunctiva of upper lid
What is trichiasis?
Normally placed hairs contacting the ocular surface.
