Disorders Of Orbit & Nasolacrimal System Flashcards
Bony fossa
Separates eye from cranial cavity
foramina & fissures
Pathway of blood vessels & nerves
Size, shape & position - closely associated w time of visual activity & feeding behavior
Pig & carnivores - incomplete
Large herbivores - complete
Orbital contents
Globe
Nicitans membrane
Glands
Fat
Extraocular muscles
Congenital anomalies
Anopthlamus
Microphthalmos
Synophthalmus
Cyclopia
Strabismus
Causes for microphthalmus
Hereditary
Merle ocular dysgenesis
Collie eye anomalies
Bovine viral diarrhea
Nutritional (hypovitaminosis)
Congenital anomalies w non viable fetus
Synophthalmia
Anophthalmia
Cyclopia
Converging strabismus
Eyes meet at a point - nose
Bilateral converging strabismus w exophthalmia (BCSE)
Inherited in jersey, German cattle breeds
Inhereited in Siamese cats
Diverging strabismus
Eyes going in different directions
Hydrocephalus - sunset eyes
Considered normal in Brachycephalic breeds
Clinical signs for strabismus
Change in orbital volume (endo/exophthalmus)
Impaired function of orbital structures
Neuro ophthalmic exam, globe retropulsion
Unilateral cranial nerve V lesion
Orbital neoplasia
Large mineralized space occupying lesion
Age related loss of retrobulbar fat
Orbital fracture w eyelid lacteration
Bilateral Extraocular Polymyositis
Exophthalmus
Increased orbital volume
Acquired disorders
Orbital cellulitis /abscess
Transoral abscess drainage
Sialoceles
MMM
Extraocular muscle myositits
Orbital neoplasia
Proptosis
Orbital cellulitis
Acute, unilateral exophthalmos
Pain in globe retropulsion & mouth opening
Protrusion of 3rd eyelid
Conjunctival hyperemia, chemosis
Periocular swelling, mucopurulent discharge
Causes for orbital cellulitis
Penetrating wound through mouth
Foreign body
Tooth root abscess
Infection of zygomatic/salivary gland
Idiopathic
Treating orbital cellulitis
Drainage
Systemic broad spectrum antibiotics
Sialoceles
Cystic structures from glandular or epithelial tissues
Typically exophthalmos and protrusion of third eyelid
Minimal pain, fluctuating swelling
Causes of Sialoceles
Trauma of head
Leakage of saliva from zygomatic gland/duct
Ulceration of oral mucosa - obstruction of saliva outflow
Treat w removal of cysts and gland
DX of Sialoceles
Ultrasounds, ct
FNA of yellowish/ fluid and blood
MMM
Eosinophilic myositis - IMM inflammatory myopathy
Temporalis, masseter, pterygoid muscles - 2M fibers
Acute phase - severe pain upon palpation, restricted jaw movements, anorexia, +/- blindness
DX for MMM
CT, MRI, muscle biopsy
TX for MMM
Oral corticosteroids
Immunomodulators for long term therapy
Endophthalmus & atrophy of muscles is common in chronic cases
Extraocular muscle myositis
IMM inflammatory myopathy
- extra ocular disease
- CD3 lymphocytic infiltration
Bilateral exophthalmos w/out 3rd eyelid - not painful, retraction of upper eyelid
DX for EMM
Ultrasound, CT, MRI - biopsy not ideal
TX for EMM
Oral corticosteroids - treatment is shorter term than MMM
Endophthalmus and strabismus is common w chronic cases
Orbital neoplasia
Primary neoplasia - arises from orbital tissue
Secondary neoplasia - invade orbit from adjacent structures or metastasize from distant areas
Slowly progressive exophthalmos - non painful, unilateral, decreased globe retropulsion, third eyelid elevation
EX for orbital neoplasia
Lymph node evaluation
Ultrasound, CT, MRI
Treatment for orbital neoplasia
Exenteration or enucleation
Palliative vs radiation
Proptosis
Sudden, forward displacement of globe w entrapment of eyelids - trauma origin
Common in Brachycephalic Breeds due to shallow orbit
Cats w this condition, trauma requires greater force = poor prognosis
TX of Proptosis
Globe replacement - tarsorrhaphy
Enucleation
Prognosis for Proptosis
Vision = guarded to poor (20%)
Positive - PLR better long term prognosis
Two or more of the extra ocular muscles are avulsed - enucleation is recommended due to compromised nerve supply, blood supply ext
Hyphens - blood inside anterior chamber = guarded
Nasolacrimal system
Thin walled conduit that drains the tear film from the eye into the nasal passages
Puncta - super and inferior
Canaliculi
Lacrimal sac
Nasolacrimal duct
Nasal puncta
Pre corneal tear film (PTF)
Functions to maintain uniform corneal surface, remove debris, deliver oxygen to Avascular cornea, provision of Antimicrobials substances in eye
Composition of PTF
Lipid - meibomian glands (outer layer)
Aqueous - lacrimal and third eyelid (middle layer)
Mucin - goblet cells in conjunctiva (closest to cornea)
Quantitative tear film deficiencies
Tear film produced is not a balanced
KCS*
Causes for quantitiative deficiency
Immune-mediated (most common)
• Congenital (alacrima, lacrimal gland hypoplasia)
• Infectious (canine distemper virus)
• Drug-induced (sulfonamides, atropine, topical anesthetics) • Iatrogenic (T.E gland removal) • Neurogenic (parasympathetic denervation)
Qualitative deficiency
Premature evaporation of tears
• Lipid or mucin deficiency •
Causes
• Marginal blepharitis / meibomianitis
• Autoimmune diseases affecting
mucocutaneous junctions • Severe cicatrization / conjunctival scarring
Testing for qualitiative tear film
Swollen rounded eyelid margins, indicating marginal blepharitis
Multiple chalazia indicating meibomiantitis
Positive uptake for rose bengal stain
Tear film breakup time test
KCS
Intense hyperemia, mucopurulent discharge, keratitis
Mucopurulent discharge & extensive Pigmentary keratitis = chronic
Infected axial stromal ulcer, malacia, diffuse corneal edema
Neurogenic KCS - dry nose, ipsilateral xeromycteria
Treating tear film deficiencies
Cholinergic agents
Immunomodulating agents
Tear substitutes
Antibacterial agents
Mucinolytic anticollagenese agents
Cholinergic agents
For neurogenic KCS
Pilocarpine (topical/oral)
Immunomoudlating agents
Topical cyclosporine
Topical tarcolimus
Antibacterial agents
Broad spectrum use is common in inadequate cleansing of ocular surface
Mucinolytic - anticollagenese agents
Topical acetylcysteine
Removal of mucous debris
Epiphora
Common
Obstruction of tear flow through nasal lacrimal system due to over production of tears
Mucopurulent punctual, conjunctival and nasal discharge
Swelling of medial Cathay region
Diagnosing epiphora
Schirmer test
Florescent dye passage
Flush NSL - normograde = eye to nose, retrograde = nose to eye
Cytology
Nasolacrimal system disorders
Bilateral punctual atresia = marked epiphora
Superior punctual & canicular foreign body = darcryocytisis
Tear staining syndrome
