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107 Cards in this Set
- Front
- Back
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What are the 4 layers of the cornea?
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- outer, non-keratinized squamous epithelium
-collagenous stroma -inner, acellular membrane (Descements) -single layer of flattened cells - the endothelium |
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What percentage of the cornea is the stroma?
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90%
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Where is the active pump for the cornea?
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in the endothelium
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How is the anterior cornea innervated?
Deep stromal layers? |
richly with non-myelinated sensory nerve fibers and is very sensitive to the touch
-deep stromal layers lack innervation |
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What is the function of the cornea?
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protective barrier and the major refractive structure of the eye
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Why are corneal scars apparent to the naked eye?
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newly arranged collagen is irregularly arranged
with stromal defects, fibroblasts lay down new collagen |
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What are the 2 sources of edema in the eye?
-why does the eye appear cloudy? |
-epithelial defects
-corneal endothelial damage (decreased pump function) - accumulation of fluid distors the organized lamellar arrangement of the stromal collagen fibrils |
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Does corneal endothelium regenerate in an adult?
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no
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What is the rate of BV growth?
- BV in response to corneal disease are... -BV in response to intraocular inflammation are... |
- corneal disease: superficial and branching
- intraocular inflammation: deeper in the cornea, straighter, and affect the cornea around its entire circumference |
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Why does corneal pigmentation occur?
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in response to corneal inflammation or irritation
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How is a dermoid cured?
What are the origins of a dermoid? |
complete excision
- ectodermal/mesodermal origins (arrises at the lateral limbal conjunctiva and extends to the cornea) |
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What is a persistent pupillary membrane?
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arises from the iris and may be attached to the endothelial surface of the cornea - causes multifocal opacities
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What is the difference between a corneal ulcer and an erosion?
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ulcer is full-thicknes and exposed stroma
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What are the CS of ulcerative keratitis - a corneal ulcer?
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acute, painful, blepharospasm, localized corneal edema, conjunctival hyperemia, epiphora
-purulent ocular discharge with secondary bacterial infection |
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What is the cause of most ulcers?
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traumatic (exogenous or endogenous)
-KCS, exposure keratitis, cehmical contact |
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What 2 viruses can cause primary ulceration?
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- feline herpes virus -1
-moraxella bovis |
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What are the 3 classifications of corneal ulcers?
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superfical, stroma (mid/deep) descemetocoeles(eye is VERY susceptible to rupture)
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What is a melting ulcer?
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- proteolytic degredation of corneal stromal collagen occurs --> resulting in rapid destruction of the cornea
-depth of involvement is difficult to tell (enzymes are from bacteria or neutrophils in the area) |
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What are the 4 tenants to diagnosing a corneal ulcer?
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1 - fluorescein stain
2 - find an underlying cause 3 - corneal cytology 4 - culture and sensitivity |
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What does fluorescein stain do?
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-stains corneal stroma bright green
-Descements membrane DOES NOT STAIN |
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What are 4 tenants to treating a corneal ulcer?
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1 - topical antibiotics
2 - topical atropine sulfate 3 - protease inhibitor 4 - conjunctival flap surgery |
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When should topical antibiotics be applied with corneal ulceration?
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in all cases - at least 3 times per day
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Why is topical atropine used in cases of corneal ulcers?
What cases would it be contraindicated? |
- used to diminish ciliary spasm and improve patient comfort
contraindicated in cases of glaucoma will decrease tear production can can complicate ulcer healing |
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When are protease inhibitors indicated for ulcers?
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melting ulcers or rapidly progressing ulcers
-slow corneal stromal degredation from bacterial proteases and endogenous proteases |
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What are the commonly used protease inhibitors?
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-topical acetylcysteine
-autogenous serum -oral doxycycline (accumulates in the corneal stroma following systemic administration) |
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When is conjunctival flap surgery indicated with corneal ulcers?
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indicated for deep stromal ulceration (>50% corneal depth), melting ulcers, descemetocoeles
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Why are conjunctival flaps good for corneal ulcers to heal?
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-provide a direct vascular supply to assist healing
-mechanical strength, fibroblasts, and epithelial cells |
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Are 3rd eyelid flaps good for treating corneal ulceration?
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no - contraindicated, esp. in most cases of corneal ulceration, esp when infection in present
-might worsen the condition - preventing medication from reaching the corneal surface and trapping necrotic debris and degredative enzymes on the corneal surface |
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What medication is truely contraindicated in the case of corneal ulcers?
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topical corticosteroids
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What does SCCED stand for and what is another name for it?
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Spontaneous Chronic Corneal Epithelial Defect
-Boxer Ulcer, Indolent Ulcer |
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What is SCCED and what is the cause of it ?
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-ulcerative condition of the cornea where the lesion remains superficial, but heals very slowly if at all and reocurs
-there is a underlying defect in the corneal stroma that disallows normal attachment of the corneal epithelium to the stroma |
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What is the treatment for SCCEP?
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debridement of all loose epithelium from the cornea followed by either:
-striate keratotomy -punctate keratotomy -apply topical antibiotic drops |
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How are superficial corneal lacerations managed?
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as an ulcer
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What is the primary treatment for deep lacerations of the globe (>50% corneal thickness)?
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sutured
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What is rupture of the cornea most often assoicated with?
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prolapse of uveal tissue (iris) --> makes recognition easy
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Corneal rupture is a surgical condition, but certain medical emergency management should be performed first. What are the 3 tenants of treatment?
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1 - topical antibiotics (solutions)
2 - topical atropine sulfate (solution) 3 - systemic antibiotics -also e-collar |
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When is the prognosis worsed for cases of corneal rupture?
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-blunt trauma - beyond the limbus
- severe hyphema -lens rupture -intraocular infection -chronic rupture |
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What is a corneal abcess?
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subepithelial (stromal) accumulation of inflammatory cells
-appears as an off-white to yellow opacity in the cornea |
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What are the CS of a corneal abcess?
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- extreme discomfort
-epiphoria -blepharospasm -corneal edema, vascularization -reflex uveitis |
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Why so corneal abcesses form?
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assoicated with infection or sterile (FB)
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What is the treatment for corneal abcess?
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-a topical antibiotic that can penetrate intact corneal epithelium
(chloramphenicol or fluoroquinolones - ciprofloxacin) -keratectomy to remove abcessed tissue is faster and more efective with conjunctival flap |
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When does pigmentery keratitis occur?
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secondary to chronic irritation such as:
-KCS -nasal fold trichiasis -entropion -distichiasis -exposure keratitis (esp. in brachycepahalic breeds) -recurrent corneal ulceration -vascularization is often present |
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What is the treatment for pigmentary keratitis?
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addressing the underlying cause
-topical cyclosporin or tacrolimus to reduce pigmentation |
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What is another name for chronic superficial keratitis (CSK) and what breed is predisposed?
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pannus
-German Shepards |
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What are the lesions assoicated with pannus?
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-superficial vascularization and pigmentation of the cornea (starteing laterally and going centrally)
-non-ulcerative -non-painful -3rd eyelid thickening and depigmentation |
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What is the cause of pannus?
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immune mediated
-more severe at high altitudes (UV light) |
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What is the treatment for CSK?
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can't be cured - need life-ling treatment
-topical anti-inflammatory medications (corticosteroids and cyclosporine or tacrolimus) -both started and then corticosteroids are tapered off with cyclosporine for long term use |
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What type of reaction occurs sometimes with administration of CAV-1 (infectious canine hepatits vaccine)>
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a type III antigen-antibody immune complex reaction
-induces a syndrome of uveitis and endothelitis |
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What are the signs of Blue eye?
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-corneal edema
-endothelial precipitates anterior uveitis sometimes progresses to glaucoma -unilateral |
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What is the treatment for Blue Eye - ICH keratouveitis?
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-topical coticosteroids until signs resolve
- topical atropine - but be careful because glaucoma can develop |
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What can cause or exacerbate lipid keratopathy?
is it sight threatening? |
corticosteroids
no |
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What is the characteristic lesion of corneal dystrophy in Shetland Sheepdogs?
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-multi-focal gray-white circular elliptical rings scattered over the cornea
-corneal lipid is also assoicated with the lesions |
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What is the treatment for corneal dystrophy in Shetland Sheepdogs?
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-topical corticosteroids
-cyclosporine or tacrolimus -treatment can control, but not cure |
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What breeds are predisposed to endothelial dystrophy?
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boston terrier, chiwawa, dachshund, basset hound
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What is the medical treatment for endothelial dystrophy?
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-topical antibiotics
-topical hyerosmotics - draw fluid out and decrease the formation and rupture of epithelial bullae -doxy if endotheliitis |
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Corneal neoplasms are very rare (SCC secondary to KCS), but they can advance from the limbus - which is most common?
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melanoma
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What is the most common cause of ulcerative keratitis in the cat?
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traumatic
FHV-1 |
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What is pathopneumonic for FHC-1?
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dendritic ulcers
-don't extend into the stroma therefore more able to detect with rose bengal stain -geographic ulcers can form from a bunch of these put together |
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What it the treatment for FHV-1?
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topical antibiotics if ulceration present
topical antivirals help speed recovery (applied at least 6 times per day) -oral famcyclovir |
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What do the lesions of feline eosinophilic keratitis/keratoconjunctivitis look like?
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rasied, proliferative lesions on the corneal surface
-pink, vascularized, multi-focal small white nodules scattered over the surface -concurent corneal ulcers -painful |
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How is feline eosinophlic keratitis/keratoconjunctivitis diagnosed?
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corneal scrapings - eosinophils, mast cells, lymphocytes, plasma cells
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What is the treatment for feline eosinophilic keratitis/keratoconjunctivitis?
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topical corticosteriods
-oral megesterol acetate (Ovaban) |
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What normally preceeds a sequestrum in the cat?
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-ulcers
-also assoicated with tear film abnormalitis and FHV-1 infections |
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What is the treatment for feline sequestrum?
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keratectomy
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What is the function of the sclera?
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-structural
-protective -attachment point for extraocular muscles |
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What is simple episcleritis?
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secotorial thickening of the anterior sclera and congestion of the associated episcleral vessels
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What is treatment for episcleritis?
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corticosteroids
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What is nodular granulomatous episclerokeratitis (NGE)?
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nodular pink masses, bilateral and non-painful that often invade into the corneal epithelium (with arc of corneal lipid degeneration)
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What is seen in histology of NGE?
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histiocytes, lymphocytes, plasma cells
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What are treatment options for NGE?
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-topical and subconjunctival corticosteroids, topical cyclosporine, systemic azathioprine
-surgical removal and cryptherapy -oral tetracycline and niacinamide |
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What is the difference between NGE and Ocular Nodular Fascitits?
What is the difference in treatment? |
-on histopath -- fibroblasts with abundant reticulin formation and lesser lymphocytes, plasma cells and histiocytes
-removeal and cryotherapy is curative (unlike NGE) |
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What is unique about diffuse scleritis?
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painful (cockerspaniels)
also involves the cornea, anteriaor uvea, and choroid/retina |
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What is the treatemnt for diffuse scleritis?
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-corticosteroids and azathioprione with relapses
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What does the conjunctiva cover?
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-MM lines the inner surface of the eyelids, exposed scleral surface (bulbar conjunctiva), and the nictitating membrane in one layer
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What is the conjunctiva composed of?
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stratified squamous epithelim over a fibrous connective tissue stroma (substantia propria)
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What is the function of the conjunctiva?
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-goblet cells produce mucin
-lymphoid tissues play a role in surface ocular immunology - epithelial cells at the limbus - provide stem cell population from which corneal epithelial cells are derived |
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Most conjuctivival disorders have what CS?
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hyperemia, chemosis (conjuntival swelling), and ocular discharge
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Is bacterial conjunctivitis in the dog primary or secondary?
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secondary to eyelid conformation and KCS (dry eye)
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What virus causes conjunctivitis?
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canine distemper virus with concurrent tracheobronchitis and rhinitis
-see viral inclusions in the first week |
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What parasite can cause conjunctivitis?
-how do you treat it? |
Thelazia californiensis in West in the cul-de seac
-flush with 0.5% tetramisole solution |
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What is the most common infectious cause of feline conjunctival and corneal disease?
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FHV-1
-80% will develop latent infection with 45% having recrudescense od CS or asypptomatic shedding |
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How do you diagnose FHV-1?
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IFA, PCR
- not serology -virus isolation is GOld Standard, but rarely done |
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What is the treatment for feline herpes?
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symptomatic - topical antibiotics to prevent secondary bacterial infections
-famcylovir, oral L-lsine |
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Does vaccination for feline herpes prevent infectin?
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no, but will lessen CS
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How is chlamydophiia diagnosed?
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intracytoplasmic inclusion bodies (first 2 weeks only), antigen on IFA, PCR, isolation
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What is the treatment for chlamydophyla?
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topical tetracycline, chloramphenicol or erythromycin - QID!!!
-systemic, tetracycline, doxycycline, or azithromycin |
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What is unique about C. felis?
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zoonotic
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What are the 3 main infective causes of feline conjunctivitis?
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FHV-1
C. felis mycoplasma - questionable because often isolated in normal cats - more likely is secondary |
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How do you diagnose allergic conjunctivitis associated with atopy?
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conj. scrapings revealing lots of lymphoctyes/plasma cells
-finding just one eosinophil is diagnositc |
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What is the treatment for allergic conjunctivitis?
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topical antihistamines and mast cell stabilizers
-topical corticosteroids |
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What can happen when treating allergic conjunctivitis with topical aminoglycosides (neomycin, gentamicin)?
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hypersensitivity reaction to the preservatives (esp Benzalkonium)
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What age dogs does canine follicular conjunctivis occur?
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young - less than 2
-usually outgrowth the condition |
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What is the presenting complaint of dogs with canine follicular conjunctiitis?
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follicular hypertrophy - clear blisters - on the bulbar surface of the nictitans
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What is the cause of canine follicualr conjuntivitis and what is the treatment?
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Cause: chronic antigenic stimulation
Treatment: symptomatic with topican anti-inflammatory (steroids and cyclosporin); irrigation may help |
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What is the ONLY condition in the cat where corticosteriods should be routinely employed?
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feline eosinophilic conjunctivitis/keratoconjunctivitis
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KCS is a common cause of conjunctivits in the dog. What is the most common cause of it?
Is KCS common in cats? |
- immune-mediated distruction of the lacrimal glands
-no not common in cats |
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In what breeds is caruncular trichiasis common?
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Shih Tzu, Lhasa Apso, Pekingese
-irritation from the hair causes the problems |
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What types of dogs do you see medial canthal pocket syndrome?
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large breeds with enopthalmaos and deep orbits
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What are the 2 major roles of the nictitating membrane?
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-protection of the cornea
-production of aqueous tears 10-60% |
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What is the primary cause of cherry eye?
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weak fascial attachements of the gland to the periorbital tissues
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What are consequences of cherry eye?
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conjunctivitis, ocular discharge, decreased tear production
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What is the treatment for cherry eye?
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-surgical repositioning of the gland
-NOT excision - first reduce swelling with topical anti-inflammatory drugs, corticosteroids and cyclosporine |
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What is the cause of scrolled cartilage and what is the treatment?
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congenital in large breed dogs
-remove folded cartilage |
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What are the causes for 3rd eyelid protrusion?
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1 - space occupying orbital lesion
2 - Horners syndrome 3- retraction of the globe 4 - enopthalmous with sedation or loss of retrobulbar fat 5 - tetanus |
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What are the 3 neoplasms of the 3rd eyelid?
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1 - adenocarcinoma (looks similar to cherry eye)
2 - melanoma 3 - papilloma |
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What is a plasmoma associated with?
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pannus
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When should a 3rd eyelid flap be used and not used?
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used: certain types of ulcers; after superifical keratectomy
not used: infected or progressive ulcers |
