Small Ani. Sx- Optho- Ocular Anatomy and the Orbit

drraythe's version from 2016-04-30 00:04


Question Answer
what are the three basic tunics of the eye? what are the components of each tunic?(1) Fibrous tunic: cornea and sclera (2) vascular tunic: "UVEAL TRACT": Iris, ciliary body, choroid (3) neural tunic: retina
what are the three things that compose the internal optic media?aqueous humor, lens, vitreous humor
2 possible ways to provide magnification for your optho exam?Slit lamp biomicroscope, Head loupes
a retinal exam consists of 2 parts...what are they?(1) Indirect ophthalmoscopy (need a light source and a lens) (2) direct ophthalmoscopy
3 ways to assess vision (if the animal can see!)(1) vision-directed bh (2) tracking (3) menace response
***What are the 4 vision robbing dzs which can rob vision in a matter of hours?cataract, uveitis, glaucoma, lens luxation (know how they interrelate!)
CNs for menace response? (in and out)In: CNII. Out: CN VII
CNs for PLR? (in and out)IN: CNII. Out: CN III
CNs for palpebral reflex?IN: CNII. Out: CN VII
When does a dog develop a menace response? horse?DOG: apprx 3mo. Horse + cow: roughly 2wk
******Minimum Data Base!!! What is included in this, IN THE RIGHT ORDER?(1) Direct & indirect examination (including menace and PLRs!) (2) Schirmer tear test (3) Stain (Rose Bengal/ Fluorescein) (4) Tonometry (5) Additional diagnostics (Cytology/ FNA/ Biopsy, Culture, Nasolacrimal flush)
what are the two components of the orbit?Bony orbit and soft tissue orbit
what are the two kinds of bony orbits? (species variation)CLOSED or OPEN boney orbit- carnivores usually have open bc need more room and flexibility with huge masseter (chewing) muscles
what is the soft tissue orbit made up of?Orbital Cone, “Extraconal” structures
what is the Orbital Cone composed of?Connective tissue, Extraocular muscles, Nerves, Blood vessels, Fat, Smooth muscle, Endorbita/periorbita
what is the Endorbita/periorbita?Fibrous connective tissue which is Next to bone of orbital wall. It Encircles the extraocular muscles ***and is the Boundary between intraconal/extraconal spaces
**what is the Boundary between intraconal/extraconal spaces?Endorbita/periorbita
what are the extraocular mm?Lateral, Medial, Dorsal, Ventral Rectus muscles, Superior and Inferior Oblique, Retractor bulbi muscle
what are the EXTRACONAL Soft Tissues and Associated Structures? (read over)MM: Temporalis, pterygoid, masseter. etc, Blood vessels and Nerves, Fat and connective tissue, Glands (Lacrimal and zygomatic salivary glands), Paranasal sinuses, Nasal cavity, Oral cavity, Teeth roots, Cranial cavity (cranial fossa)


Question Answer
what is EXOPHTHALMOS?Globe is too rostral
what is ENOPHTHALMOS?Globe is too caudal (Globe sits too far caudal within the orbit).
what is PROPTOSIS?Equator of globe anterior to palpebral fissure (so like exopthalmos but with 50% of the eyeball past the palp. fissure) (palp fissue is the opening of edges of eyelids)
should do Retropulsion to exam for orbital dz- what is this and what is a normal response?push animals eyes back into the socket a bit- should NOT be painful
basic two things you are looking at for Ophthalmic exam?Anterior segment, fundus
what would you not think of to examine if suspecting orbital dz?ORAL EXAM!
Why MUST you look from above if you get a patient with a big bulgey looking eye?to differentiate exophthalmos and Buphthalmos
explain exophthalmos vs Buphthalmosbu= the actual globe is too big and its stretched-- only glaucoma causes this (chronic). CANT SAVE A BUPHTHALMIC EYE. Exophthalmos is when a normal sized eye is pushed forward
what is the only accurate way to measure to tell diff between exophthalmos and buphthalmos?measure limbus to limbus (junction of the clear cornea to white sclera-- in buphthalmic it'll be stretched so inc distance)
4 big Clinical Signs of Orbital Disease?(1) Increased or Decreased Scleral Show (2) Decreased Retropulsion (3) Elevation of Nictitans (4) Difficulty or Discomfort Opening Mouth
handy abbreviations for left eye, right eye, both eyes? neither eyes?OS= left eye. OD= right eye. OU= both eyes. OX= neither eye
4 non-specialty diagnostics for orbital dz? 3 specialty?NON: Physical exam, CBC/chemistry profile, Skull radiographs, Fine needle aspirates. SPECIALTY: Orbital ultrasonography, Angiography, Advanced imaging (CT/MRI)
why is history important when looking at a pt with enophthalmos?Congenital vs. acquired
what are the two dzs which cause CONGENITAL enophthalmos?Microphthalmos, Anophthalmos
what is Microphthalmos? how do dogs get this? what is it often associated with?This is when Globe does not form to full size. It is a CONGENITAL defect, and Usually has multiple ocular defects. Often associated with merle coat (poor prog)
what is Anophthalmos? how do dogs get this?CONGENITAL prob. Globe never develops. (poor prog)
Acquired Enophthalmos can be split into two categories...(1) Globe is too small – “phthisis bulbi” (2) Normal Globe Size
what is phthisis bulbi?when the Globe is too small as End stage of some other disease of the globe (Glaucoma, penetrating or blunt trauma, uveitis) (chronic trauma-- has shriveled up like a raisen)
if there is acquired enophthalmos and the globe size is normal, what has occurred?occurs due to loss of tissue volume within the orbit-exs) Loss of fat- emaciation. Loss of fluid – dehydration. Atrophy of soft tissue – end result of scarring and contraction after orbital inflammation/radiation
what are two Commonly Related Conditions to exophthalmos?Lagophthalmos (inability to completely close the eyelids), and Strabismus (deviation of the “visual axis”)
what is Lagophthalmos?inability to completely close the eyelids
what is Strabismus?deviation of the “visual axis”
exopthalmos is Often Associated Clinical Signs (depending on the etiology)... examples?+/- Conjunctival hyperemia, +/- Conjunctival swelling (chemosis), +/- 3rd eyelid elevation, +/- pain, +/- keratitis
she mentioned when describing an eye to work from outside inso like, there discharge, and the eyelids are puffy, then the conjunctiva is red, etc...
cause of Exophthalmos is SPACE occupation...what are the two things that can occupy space? examples?
Exophthalmos Etiology--> Inflammatory Diseases--> 3 dzs?(1) Orbital abscess (2) Orbital cellulitis (3) Myositis (Masticatory or Extraocular)
Exophthalmos--> Orbital Cellulitis/Abscess--> what are common etiologies of this?Tooth root abscesses, Paranasal sinus infections, Hematogenous spread of infection, Penetrating injury / foreign body
Exophthalmos--> Orbital Cellulitis/Abscess--> clinical signs?Usually unilateral, 3rd eyelid protrusion, Conjunctival hyperemia, ***Pain !!! (esp. opening mouth), Fever, Inappetance, Inflammatory leukogram
Exophthalmos--> Orbital Cellulitis/Abscess--> therapy/tx?Systemic antibiotics, +/- drainage, Soft food, +/- topical antibiotics, Corneal lubrication
easy way to tell if tumor vs abscess causing exophthalmos?open up their mouth! if they SCREAM IN PAIN, it's probably exophthalmos
explain stick chewings relationship to Orbital Cellulitis/Abscesspterygopalatine fossa--> stick goes up there--> abscess. So look for swelling in the mouth near the fossa!
how does Masticatory Muscle Myositis present? (ocular and non-ocular signs). Acutely? Chronically?acute: not eye: Acute, recurrent episodes 1-3 wk durations of Facial muscle inflammation (Pterygoid, temporalis, masseter), Pain on jaw movement, Pyrexia. EYE: Bilateral exophthalmos, Nictitans elevation.... chronic: Atrophy/fibrosis, Enophthalmos
what is the truly diagnostic test for Masticatory Muscle Myositis?2M Autoantibody test (serum)
what does CBC/chem look like with Masticatory Muscle Myositis?Peripheral eosinophilia (+/-), Creatine kinase elevated
what will histopath of Masticatory Muscle Myositis look like?Neutrophils, eosinophils
how do you treat the acute stage of Masticatory Muscle Myositis? Chronic?Systemic immunosupression (Corticosteroids, +/- azathioprine) and supportive care. Chronic is just conservative management
gee, this dog sure looks worried... why?it has Extraocular Muscle Myositis!
explain what is happening in Extraocular Muscle Myositis, what are the clinical signs? breed dispositions?it is an Autoimmune myositis which often presents as Bilateral exophthalmos (“Stressed” look, Scleral show, Fixed gaze, NO nictitans protrusion), and it is NON-PAINFUL! Golden retrievers overrepresented
Extraocular Muscle Myositis vs Masticatory Muscle MyositisMMM has jaw pain and Nictitans elevation, EMM DOESNT
how do you dx Extraocular Muscle Myositis?Clinical presentation, Imaging (US, CT, MRI), Biopsy (only for specialist)
how do you treat Extraocular Muscle Myositisimmunosuppression
what is the prognosis of Extraocular Muscle Myositis? what are problems you get with chronic cases?Recurrences common :( in chronic cases you will see Enophthalmos, Strabismus/fibrosis
is orbital neoplasia usually benign or malig?malig
how does orbital neoplasia present?Gradual onset, Exophthalmos, Nictitans elevation, Lack of retropulsion, Absence of pain opening mouth
what should you know about 1* and 2* neoplasias of the orbit?basically anything can show up there. guarded prog often malig. She didn't seem to want us to memorize the huge list in the ppt
Rare Causes of Exophthalmos? (fluid or air!)(1) FLUID: (a) Cystic structures (Salivary mucocele, Lacrimal glandular) (b) blood: Hematoma, Orbital varix, Arteriovenous fistula (2) AIR: Emphysema (traumatic)
WHAT IS PROPTOSIS (the definition she gives later that is actually good)Sudden forward displacement of the globe with entrapment of the eyelids behind the globe’s equator. Usually due to some sort of trauma, more common in brachycephalics
Positive prognostic indicators of proptosis? (2)(1) Positive consensual PLR (2) Voluntary movement of the globe – some degree of extraocular muscle attachment remains
what is NOT a reliable indicator of a positive prognosis for proptosis?Pupil size – is not a reliable indicator (Some texts state miotic pupil indicates parasympathetic innervation is intact; however, is not a dependable prognosticator)
Negative prognostic indicators of proptosis (5)(1) Hyphema: indicates severe uveal trauma and/or retinal detachment or tear (2) Corneoscleral laceration (3) Rupture of three or more extraocular muscles (4) Transected optic nerve (5) Chronic proptosis (>48 hours)
proptosis prognosis is worse in what kinda pts? (3)(1) Dolichocephalics (2) cats with deep orbits (3) species with a complete bony orbit (equine, bovine, etc.)
if owner calls you about proptosis, and they are coming in, tell them to...Inform owner to keep eye moist during transport (KY jelly, artificial tears, olive or corn oil)
possible complications of proptosis?Lagophthalmos (Cant close eyelids), Keratoconjunctivitis sicca, Strabismus (superiolateral strabismus as the medial rectus and ventral oblique muscles are most commonly torn), Blindness (retinal degeneration, optic nerve atrophy, glaucoma), Phthisis bulbi

Surgical Procedures (be familiar with types & indications)

Question Answer
what is Eviscerationremoval of intraocular contents followed by prosthesis
what is Enucleation? what are the two kinds?removal of the globe. Can be Transpalpebral or Subconjuctival
what is Exenteration?removal of ALL of the orbital contents (not just the globe) (usually do this bc neoplasia)
what are A, B, and C? A: Enucleation, B: Exenteration, C: Evisceration
explain how Subconjunctival enucleation worksRemoval “through” conjunctiva. Must remember to remove nictitans and residual conjuntiva. Better for histopath (Cleaner sample)
explain how Transpalpebral enucleation worksRemoval “through” eyelids. Infected eyes, Intraocular neoplasia
which enucleation technique for infected/neoplastic eyes?transpalpebral
which enucleation technique for better histopath bc cleaner sample?subconjunctival
when doing enucleation, what do you do about the optic nerve?Do not ligate optic nerve! No traction on optic nerve in cats especially!
when should you enucleate the globe with proptosis?Enucleate if globe is ruptured, obvious optic nerve transection, or only conjunctival attachments remain, ie. “hanging by a thread” (When in doubt, replace the globe)
(idk if she wanted us to know proptosis globe replacement over it if you wanna)slides 64,65 of first ppt