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Ophthalmology 422

QuestionAnswer
Ectropion General Facts - Mostly canines - Breed related(Cocker Spaniel, Bloodhounds, Giant breeds) - Age related (older dogs that have weakened eyelid muscles)
Ectropion - Secondary Problems - Blepharospasm - Epiphora - Corneal ulceration - Corneal melanosis - Corneal vascularization
Ectropion - Treatment - often not necessary - lubrication - Antibiotic/steroid ointment - Wedge resection
4 most common canine ocular neoplasias - Meibomian adenoma (most common; age related) - Papilloma (puppies only) - melanoma(very old dogs) - lymphoma (secondary metastasis to the eyelids)
Meibomian adenoma Clinical signs - papilloma-like projection from eyelid margin - swelling of the affected gland - upper lid more commonly affected - variable size - blepharospasm if ulcerating - rarely metastasizes
Meibomian adenoma Treatment - Curettage and cryotherapy - wedge resection
Most common feline ocular neoplasia - squamous cell carcinoma (most common by far) - fibrosarcoma - mast cell tumor - basal cell carcinoma - lymphoma
Feline eyelid squamous cell carcinoma Clinical signs - ulcerative lesion - lower lid most common - white or lightly pigmented cats are predisposed (exacerbated by UV exposure) - metastasis occurs late
Feline eyelid squamous cell carcinoma Treatment - Radiation is most effective - Surgical excision (as an adjunct to radiation) - cryotherapy
Equine ocular neoplasia - squamous cell carcinoma (most common by far) - melanoma - sarcoid - fibrosarcoma - lymphoma
Equine eyelid squamous cell carcinoma 3 locations - eyelid - anterior surface of the third eyelid - lateral aspect of the limbus **equally distributed**
How is the equine eyelid squamous cell carcinoma different from the feline? - more proliferative mass (can be palpated) - non-ulcerative
Equine breeds predisposed to squamous cell carcinoma - draft breeds - appaloosas - paints
Equine squamous cell carcinoma Treatment - most difficult to treat (because usually not found until late stage) - surgical debulking - chemotherapy (cisplatin)
Bovine ocular neoplasia - squamous cell carcinoma (most common)
Bovine squamous cell carcinoma 3 locations - limbus (75%) - eyelid and third eyelid (25%)
Stages of bovine eyelid squamous cell carcinoma - thickening of eyelid skin - proliferative mass (malignant form) - Metastasis (to local salivary glands and lymph nodes)
Bovine eyelid squamous cell carcinoma Treatment - may not treat - economic decision - not all precursors progress - surgical debulking - cryotherapy
Distichiasis general facts - undifferentiated meibomian gland produces cilia - the cilia emerges from the meibomian gland duct - the cilia may contact the cornea or conjuntiva and cause irritation
Distichiasis breeds - American cocker spaniels - golden retrievers
Distichiasis Treatment - manual epilation to confirm diagnosis - remove cilia and wait to see if clinical signs resolve - with confirmation of the diagnosis, cryotherapy - warn O that it may depigment the area of treatment
Ectopic cilia General Facts - failure of differentiation of meibomian gland --> cilia grows out of the gland and through palpebral conjunctiva - usually happens in the upper lid at the 12 o'clock position
Ectopic cilia Clinical signs - usually 8-12mo of age - marked blepharospasm - epiphora - vertically linear superficial corneal ulcer - raised papilla
Ectopic cilia Treatment - excision - cryotherapy (to remove cilia producing tissue)
Trichiasis General Facts - hair from normal site in contact with cornea/conjunctiva - most frequently in dogs - brachycephalics - yorkies, poodles, breeds with long facial hair
Trichiasis Clinical signs - periocular hair touching ocular surface - most often it doesn't cause irritation - just wicks tears onto the face
Trichiasis most common origin of hair - medial canthus - nasal folds
Trichiasis Treatment - usually not indicated - cryotherapy - lid surgery (to roll the lids out)
Traumatic eye injuries General facts - abrasions --> first aid - full thickness lacerations --> Sx repair - lateral aspect of the upper lid is most frequently injured - if injury is medial, need to check the nasolacrimal duct patency
Traumatic eye injuries causes - Fight wounds - Environmental objects
Traumatic eye injuries Treatment - minimal debridement - 2 layer closure - orbicularis oculi m. - skin - ID and reconstruct inferior nasolacrimal system - systemic and topical antibiotics
Traumatic eye injuries what layer is the primary holding layer when surgically closing a laceration? - the orbicularis oculi m.
Bacterial Blepharitis General Facts - overgrowth of surface bacterial flora - enters the eyelid via the meibomian gland ducts - Staph and Strep most common bacteria - Hypersensitivity to staph toxins
Bacterial blepharitis Clinical Signs - eyelid swelling - blepharospasm - excoriation - alopecia - mucopurulent discharge - granuloma formation - usually bilateral (in dogs) - recurrence is common
Bacterial blepharitis Treatment - Topical antibiotic/steroid - Oral antibiotics - Oral prednisone (low anti-inflammatory dose for hypersensitivity component) - Warm compresses (pain relief and reduction of swelling) - Autogenous vaccines (recurrent/chronic cases)
Chalazion General facts - Older dogs - Obstruction of the meibomian duct - Accumulation of meibomian secretion - Rupture of the meibomian gland - Granulomatous reaction
Chalazion Clinical Signs - nodular swelling within the eyelid - No inflammation - No pain - Yellow white appearance through palpebral conjunctiva (viewed from underneath the eyelid)
Chalazion Treatment - incision through the palpebral conjunctiva - curettage of the glandular and granulomatous material - topical antibiotic/steroid
Eyelid agenesis General Facts - congenital condition - most commonly in cats
Eyelid agenesis Clinical signs - Absence of lateral 1/2 to 2/3 of the upper eyelid - always bilateral (but not symmetrical) - secondary trichiasis and exposure keratitis - (+/-) microphthalmos and persistent pupillary membrane
Eyelid agenesis Treatment - lubricants (reduce trichiasis irritation, reduce exposure) - cryotherapy (of trichiasis hairs) - blepharoplastic procedures (transplant part of the lower lid to the upper lid)
Neonatal ophthalmia General facts - infection under eyelids before opening - staph, strep, herpesvirus
Ankyloblepharon - adhesion of the ciliary edges of the upper and lower eyelids to each other - normal in dogs and cats 10-14days old
neonatal ophthalmia clinical signs - inflamed, distended eyelids - purulent discharge - conjunctival hyperemia - chemosis - (+/-) corneal ulceration
Neonatal ophthalmia Treatment - open eyelids (digital manipulation, blunt probe) - flush with dilute betadine solution - topical antibiotics
Retained Spectacle General Facts - in snakes - fused eyelids = spectacle - spectacle contains blood vessels and sheds regularly with skin (ecdysis) - abnormal if retained (not shed)
Retained Spectacle clinical signs - Dull, cloudy appearance - NOT the cornea
Retained Spectacle Causes - dry environment - systemic disease - mite or tick infestation - injury to the spectacle
Retained Spectacle Treatment - conservative (don't peel if off) - misting, soaking the spectacle - increase humidity - Add "furniture" to encourage normal shedding - address systemic disease
4 primary layers of the cornea - epithelium - stroma - Descemet's membrane - endothelium
Corneal epithelium general facts - 5-10cells thick - constant turnover - hydrophobic - won't take up fluorescein dye - mechanical barrier
2 organisms that can directly infect the corneal epithelium - feline herpesvirus - moraxella bovis
Corneal stroma general facts - 90% of the corneas thickness - lamellar arrangement of collagen fibers - hydrophilic - takes up fluorescein dye - readily susceptible to infection - densely innervated by CN V (outer half is innervated; inner half is not)
Decemet's membrane General facts - basement membrane of the corneal endothelium - very elastic - last barrier to perforation - produced throughout life - becomes thickened as animal ages - hydrophobic - won't take up flourescein dye
Corneal endothelium - monolayer of epithelium ("posterior corneal epithelium") - Na/K pump removes fluid from corneal stroma
2 layers that control the hydration state of the cornea - epithelium (hydrophobicity restricts tears from entering the stroma) - endothelium (Na/K pump actively transports fluid from stroma)
5 factors that contribute to corneal transparency 1. avascularity 2. relative dehydration 3. orderly arrangement of stromal collagen fibrils 4. lack of pigment 5. non-keratinized epithelium
2 sources of nutrition for the cornea 1. tears (for anterior cornea) 2. aqueous (for posterior cornea)
3 functions of the cornea 1. transmission of light 2. refraction of light 3. fibrous outer layer of eye protection
Signs of corneal disease - edema - cellular infiltrate - lipid/mineral deposits - fibrosis - precipitates - blood vessels - melanin - neoplasms
corneal edema - need to ID layer allowing edema (epithelium or endothelium) - entire cornea (diffuse) or sectional - epithelium affected --> sectional - endothelium affecthed --> diffuse, more severe - non-specific sign
Corneal cellular infiltrate - infection present = stromal abscess - specific sign
Corneal lipid/mineral deposits - usually cholesterol, other lipids, or Ca++ salts - non-specific sign
Corneal fibrosis - some past injury - non-specific
Corneal precipitates - accumulations of inflammatory cells and debris on the endothelial surface - always ssecondary to past or present anterior uveitis - specific sign - can cause corneal edema
Corneal blood vessels - always pathologic (response to injury) - diffuse or sectional? - tree-like with fine branching = superficial corneal vascularization - short non branching = deep corneal vascularization - takes 2-3days to initiate, then 1mm/day - non-specific sign
Corneal melanosis - response to chronic irritation/inflammation - varies by species - non-specific sign
Corneal neoplasm - rare in cats and dogs - common in horses and cattle
Normal corneal ulcer healing "slide and divide" - sliding (migration) of epithelial cells to cover the exposed stroma - formation of basement membrane between epithelium and stroma - mitosis to restore normal # of layers of the corneal epithelium
Uncomplicated corneal ulcer Clinical signs - epithelium only, no stromal loss - Heals within 7days - No change in stromal character (stromal melting) - No extensive vascularization
uncomplicated corneal ulcer Treatment - ABSOLUTELY NO TOPICAL STEROIDS - topical broad spectrum ABs - topical atropine - Ecollar - recheck 2-3days, then 7 days
Complicated corneal ulcer Clinical signs - increasing depth - stromal infiltrate (specific sign) - change in stromal character (specific sign) - corneal vascularization - hasn't healed in 7-10 days
2 signs of a complicated corneal ulcer that are specific for infection - stromal infiltrate - change in stromal character (stromal melting)
Complicated corneal ulcer Common causes - infection (bacterial, fungal, viral) - foreign bodies - exposure - entropion - ectopic cilia - persistent ulcer syndrome ("boxer" ulcer) - very common in SA practice
Complicated corneal ulcer Diagnosis of infection - cytology - C&S
Complicated corneal ulcer Treatment - referral is first choice - vigorous AB's/antifungals (q2hr) - topical serum - Ecollar - warm compresses - cage rest
Complicated corneal ulcer Exposure Clinical signs - most frequent with brachycephalics - centrally located - round firm edges
Complicated corneal ulcer Treatment of exposure ulcer - frequent AB ointment - (+/-) atropine - possibly tarsorrhaphy (closure of eyelids)
Complicated corneal ulcer Persistent ulcer syndrome clinical signs - middle aged or older - redundant epithelium around periphery - forms a sheet that floats in the tear film
Complicated corneal ulcer Persistent ulcer syndrome Treatment - corneal debridement with Q-tip - grid keratotomy - only in dogs - never in cats and horses - Medical Tx as uncomplicated
why would you never do a grid keratotomy in a cat or horse with persistent ulcer syndrome? because, in addition to stimulating basement membrane deposition, scoring the cornea will embed infectious material Cats - prone to herpes Horses - prone to infectious ulcers
Chronic superficial keratitis general facts - immune mediated - affects young adults - German shepherds predisposed - UV light alters stromal proteins and causes an immune response - lymphocyte migration --> cytokines --> inflammation - AKA pannus
Chronic superficial keratitis clinical signs acute - fibrovascular invasion just under the corneal epithelium in the ventrolateral cornea - plasmoma = third eyelid thickening
Chronic superficial keratitis clinical signs chronic - corneal melanosis - blindness
Differential diagnoses for Chronic superficial keratitis - KCS - Corneal ulceration
Chronic superficial keratitis Treatment - Topical steroids (neopolydex, prednisolone) - topical cyclosporine
Exposure keratitis General facts - usually brachycephalic dogs - eyelids don't meet fully in medial aspect - age related - weakening of the orbicularis oculi m. - Cats with eyelid agenesis - secondary to eyelid injury
Exposure keratitis Clinical signs - corneal vessels and melanosis medially - may lead to ulcers
Exposure keratitis Causes - conformation, breed related - eyelid agenesis - age related weakening of the orbicularis oculi m. - eyelid injury
Exposure keratitis Treatment - refer if ulcerated - treat underlying prob (agenesis, lid conformation problem) - topical AB/steroid ointment until keratitis controlled, then reduce - topical lubricating ointment long term
Corneal degeneration General facts - secondary to injury or inflammation - crystalline or chalky deposits under epithelium (Very superficial) - lipid and Ca salts - unilateral or bilateral - Painful/inflammatory - can lead to chronic recurrent ulceration - exclusively older pati
Corneal degeneration Clinical signs - roughened surface of cornea - blepharospasm - recurrent ulceration (from chalky deposits flaking off)
Corneal degeneration Causes - aberrant healing response - secondary to trauma, irritation, inflammation
Corneal degeneration Treatment - ABs for relief - keratectomy for permanent resolution
Corneal Dystrophy General facts - primary heritable defect - resembles corneal degeneration
Corneal Dystrophy Clinical signs - crystalline, ground-glass deposits - under corneal epithelium - bilateral, but not symmetric - no pain, no inflammation - no vision defect - seen in young patients (1-2yrs)
Corneal Dystrophy Treatment - not indicated - no pain - no vision defect
Feline herpesvirus General facts - FHV-1 infects corneal epithelial cells and conjunctival cells - May result in - corneal sequestrum - eosinophilic keratitis
Feline herpesvirus clinical signs - blepharospasm - epiphora - conjunctival hyperemia - chemosis - corneal vessels - Dendritic ulcers - focal pinpoint cellular infiltrate
What clinical sign is pathognomonic for FHV-1 - dendritic ulcers
How are cats most commonly infected with FHV-1? Did an adult cat with an outbreak get FHV-1 from the new kitten in the household? - in utero - No, the adult cat probably was infected with FHV-1 in utero and just had an outbreak in response to the stress of a new kitten in the household.
Feline herpesvirus Treatment - Topical antivirals (idoxuridine, cidofovir) - Oral L-lysine - TOPICAL STEROIDS ARE ABSOLUTELY CONTRAINDICATED! - treatment isn't curative, just shortens the course of the episode
Corneal sequestrum General facts - unique to domestic cats
Corneal sequestrum Clinical signs - distinctive dark brown plaque - necrotic stroma - NOT MELANIN - painful - can lead to rupture
Corneal sequestrum Causes - Herpesvirus plays a role, but is not the only factor - chronic exposure - as in brachycephalics
Corneal sequestrum Treatment - if there is a vascular response - will slough on its own - if no vascular response - keratectomy - conjunctival graft to the stromal bed
Eosinophilic keratitis General facts - most frequently in cats - also seen in horses - associated with herpesvirus
Eosinophilic keratitis Clinical signs - fibrovascular infiltrate with white "caseous" islands - nests of eosinophils
Eosinophilic keratitis diagnosis - clinical signs - fibrovascular infiltrate - caseous plaques - cytology - scrape white plaque and stain for eosinophils
Eosinophilic keratitis Treatment - Topical steroids and antivirals or - megesterol acetate
Infectious Bovine Keratitis General facts - common - economically significant - caused by moraxella bovis predominantly - Herefords are most affected breed - younger affected more than older
Infectious Bovine Keratitis Clinical signs - variable severity - initially unilateral - blepharospasm - epiphora - central stromal infiltrate - vigorous vascular response - perforation, phthisis bulbi possible
Infectious Bovine Keratitis Treatment - Can run its course without Tx - may rupture cornea and scar in - Penicillin - Ampicillin - Oxytetracycline (Tx of choice)
Corneal neoplasia in dogs Genneral facts - relatively rare compared to horses and cattle - limbal melanoma most common - hemangioma/sarcoma - lymphoma manifesting in corneal - squamous cell CA very rare
Limbal melanoma Clinical signs - Dark mass centered on limbus - extends to the sclera and cornea - unilateral - more aggressive in younger dogs - German shepherds predisposed - have to distinguish from anterior corneal melanoma growing into the sclera
Corneal hemoangioma/sarcoma Clinical signs - blood blisters - lateral aspect of the limbus
Corneal lymphoma Clinical signs - bilateral - 360 degree corneal vessels and white creamy infiltrate - eyelids swollen
Treatment of corneal neoplasms Limbal melanoma, hemangioma/hemangiosarcoma, SCC - require excision and adjunctive Tx - cryotherapy - radiation
Treatment of corneal neoplasms Recurrent hemangiosarcoma - enucleation
Treatment of corneal neoplasms Lymphosarcoma - treat symptomatically
Corneal neoplasia in cats General facts - limbal melanoma/cytoma most common - still rare - Dx and Tx same as dog
corneal neoplasia in horses - limbal scc most common
Three common locations for equine limbal squamous cell carcinoma 1. eyelids 2. anterior surface of the third eyelid 3. overlying the lateral aspect of the limbus
primary causes of limbal SCC in horses - UV light - breed predisposition - draft horses - appaloosas
Equine limbal SCC Treatment - keratectomy (cytoreductive) - adjunctive - cryotherapy - radiation - high success rate
Corneal neoplasia in cows General facts - SCC by far the most common - important economic loss
2 locations of bovine SCC - limbus (75%) - bulbar conjunctiva
Bovine corneal SCC Clinical signs - starts as a plaque and progresses - metastasis late to regional lymph nodes and parotid salivary gland
Bovine corneal SCC causes - increasing age - females may be predisposed - breed - Herefords (have light periocular pigmentation) - UV exposure - nutritional status
Bovine corneal SCC Treatment - same as horse, but may elect for enucleation for economic reasons
Corneal dermoid General facts - congenital - Choristoma = normal tissue in an abnormal location - mostly in dogs but also seen in cats, horses, cattle - breed predisposition (GSD, St. Bernard, Dachshund)
Corneal dermoid clinical signs - choristoma - located laterally - at the lateral limbus - can involve the lateral canthus
Corneal dermoid Treatment - keratectomy - reconstruct lateral canthus
Components of the lacrimal system - lacrimal gland - gland of the third eyelid - meibomian glands - goblet cells - lacrimal drainage apparatus
Components of the lacrimal system that are responsible for production of the tear film - lacrimal gland - gland of the third eyelid - meibomian glands - goblet cells
Lacrimal glands and ducts - position - innervation - function - dorsolateral in orbit - innervated by lacrimal nerve (parasympathetic) - produces aqueous portion of tear film (nutrition and immunologic agents) -
parasympathomimmetic drugs _________ tear production increase
parasympatholytic drugs __________tear production decrease
Gland of the third eyelid -position -innervation -function - located on posterior surface of the third eyelid - parasympathetically innervated - produces aqueous portion of the tear film
Meibomian glands -location -function - located in radial fashion within eyelids - ducts are landmark of eyelid margin - produce lipid portion of tear film - prevents evaporation - provides film like quality to tears
Three layers of tear film, where they are produced, and what function they serve 1.superficial- lipid -meibomian gland -prevents evaporation; film like quality 2.middle- aqueous -gland of the third eyelid -lacrimal glands -nutrition; immunological 3.inner- mucous -Goblet cells -anchors tear film
Goblet cells of the lacrimal system - location - function - located in conjunctiva, (most numerous in the fornix) - produces mucous portion of tear film - anchors tear film to corneal epithelium
Nasolacrimal drainage apparatus - lacrimal puncta (superior and inferior) - canaliculi - nasolacrimal duct - nasal puncta
Which species only has inferior lacrimal puncta rabbits
Functions of the lacrimal system - provide nutrition to the ocular surface - remove metabolic wastes and debris - provide lubrication to ocular surface
General signs of disease of the lacrimal system - tear production problems - quantitative - qualitative - tear drainage problems - epiphora - discharge
Lacrimal system diagnostics - schirmer tear test - fluoroscein dye - nasolacrimal flush
Schirmer tear test - measures aqueous tear production
Fluoroscein dye passage - tests patency of nasolacrimal duct - potential for false negatives (animal may swallow the flush; especially brachycephalics) - if + test, duct is patent
Nasolacrimal flush - can locate and relieve obstructions
Keratoconjunctivitis sicca General facts - reduction aqueous portion of tear film - most common in dogs
Keratoconjunctivitis sicca Clinical signs - mucoid discharge - blepharospasm - conjunctival hyperemia - 360 degree corneal vessels (cornea trying to get nutrition elsewhere) - corneal melanosis
Keratoconjunctivitis sicca Causes - immune mediated (75% in dogs) - drug therapy - TMS - atropine - general anesthesia - etodolac (severe and permanent) - iatrogenic (removal of gland of third eyeld) - trauma to lacrimal nerve - infectious (CDV)
Keratoconjunctivitis sicca Diagnosis - clinical signs - confirm with schirmer tear test
Keratoconjunctivitis sicca Treatment knowing underlying cause doesn't affect how you treat, just how long... - topical cyclosporine - topical AB/steroid - client education
Developmental drainage obstruction General facts - imperforate punctum and micropunctum (most common) - canalicular atresia rare - most common in dogs - nasal imperforate punctum is seen in horses
Developmental drainage obstruction Clinical signs - depends on if obstruction is complete or not - dogs have epiphora from birth - poor passage of fluoroscein dye - NL flush - nothing from inferior punctum (dogs) - nothing from nasal punctum (horses) - horses have chronic purulent discharge
Developmental drainage obstruction Treatment Easy and effective Sx Dogs - flush superior punctum and look for bleb where inferior punctum should be - incise conjunctiva over imperforate punctum - topical AB/steroid Horses - place cannula and thread down - excise skin covering nasal punctum
Foreign body obstruction of lacrimal drainage General facts - plant awns (foxtails) - sand - seasonal variation
Foreign body obstruction of lacrimal drainage Clincal signs - Painful - Blepharospasm - mucopurulent discharge - medial canthal swelling - negative fluoroscein dye passage - NL flush diminished or negative
Foreign body obstruction of lacrimal drainage Treatment - vigorous flushing (+/-) anesthesia - dislodge/retrieve foreign body - cannulate NL system and leave in place for 3-4wks - topical AB/steroid
Inflammatory obstruction of lacrimal drainage General facts - inflammatory debris without foreign body - descending infection - stagnant tear drainage
Inflammatory obstruction of lacrimal drainage Clinical signs - mucopurulent discharge - no medial canthal swelling - not painful - negative fluoroscein dye passage - NL flush easy and often produces mucoid or mucopurulent plug
Inflammatory obstruction of lacrimal drainage Causes - infection of the most proximal lacrimal drainage apparatus
Inflammatory obstruction of lacrimal drainage Treatment - NL flush (+/- betadine solution) - topical AB/steroid
Anatomy of the iris Anterior border layer Stroma Posterior epithelial layer Corpora nigra
Anterior border layer of the iris - fibroblasts - melanocytes - no continuous epithelial layer
Stroma of the iris - blood vessels - collagen fibers - fibroblasts - chromatophores - melanocytes
Muscles of the iris sphincter muscle - smooth muscle - stronger than dilator - innervated by CNIII - parasympathetic innervation Dilator muscle - smooth muscle - sypathetic innervation - continuous with outer, pigmented, ciliary body epithelium
Posterior epithelial layer of the iris - densely pigmented (melanin) - continuous with inner, non-pigmented, ciliary epithelium
Corpora nigra - found in most herbivores - cystic dilation of the posterior iris epithelium
Ciliary body epithelium Inner, non-pigmented (NPE) - extension of sensory retina - junctions of these cells make up the Blood Aqueous Barrier (BAB) Outer, pigmented epithelium - extension of retinal pigmented epithelium
Blood-aqueous barrier - ciliary body vessels (epithelial portion) - iridal vessels (endothelial portion) - prostaglandins
Ciliary body vessels - located in iridal stroma - fenestrated, leak plasma - junctional complexes along the lateral borders of the NPE
Iridal vessels - non-fenestrated capillaries
Prostaglandins of the BAB - released after initiating event of anterior uveitis - interfers with the junctional complexes at the lateral borders of the NPE - compromises the BAB
Functions of the anterior uvea - regulate light entry by changing pupil size - accomodation - production of aqueous
General signs of disease of the anterior uvea - change in appearance of the iris - change in aqueous - secondary effects on the cornea and lens
Created by: modonnell