Exam 4 Flashcards

Question

Inverted eyelid cartilage identification and post operative complication following repair

Answer 1

Eversion of the Third eyelid Cartilage -Outward curling of the third eyelid cartilage occurs most often in a young, large and giant breed dogs -Burmese most commonly affected cat -Can be misinterpreted as gland prolapse -Tearing and conjunctivitis present -Tx: surgical excision of the deformed section of cartilage -Incision in conjunctiva and dissection -Round up the edges of cartilage to avoid irritation -Post operative antibiotic ointment q 8 hr for 5-10 days **Recurrence of defect is unlikely, but prolapse of the nicitans gland may follow correction** -Thermal cautery may be used for mild defects

Answer 2

Distichia -Hairs that arise from the meibomian gland orifices due to misplaced follicles within the adjacent glands **Their presence does not warrant their removal** -Treatment if tearing, conjunctival irritation or corneal ulceration -Cryoepilation is the most practical treatment -Chalazion forceps, nitrous oxide cryoprobe, freeze, thaw, then repeat freeze. -Topical antibiotic q 8hr for 7-10 days Ectopic cilia -Distichia that has erupted through the palpebral conjunctiva of the eyelid -Discomfort, corneal ulcerations often -Young classically affected -Squinting and tearing -En bloc resection is curative, sparing the margin Trichiasis -Normal eyelashes with growth toward the eye -Contact with ocular surfaces, irritation, ulceration. -Congenital problem in small breed dogs, brachycephalic -Cryoepilation is commonly used to destroy the offending follicles -Surgical eversion of the lid margin can redirect the hairs -Injectable collagen filler can also be used to restore normal cilia position

Answer 3

Diseases of the Posterior Segment (Fundus)

Answer 4

Fundus -Composite picture formed by the optic nerve head (optic disc, optic papilla), sensory retina, retinal pigmented epithelium, choroid, tapetum and sclera, a picture influenced by the animal's species, breed, age, and coat color. Sclera -White to pale yellow -Visibility depends on the degree of pigmentation in the overlying chorioid and retinal pigmented epithelium as well as the degree of tapetal development Choroid -AKA posterior uvea -Lies adjacent to the sclera -Normal choroid vessels should be small and uniform size -Vessels radiate from the optic papilla in spoke-like fashion -Choroidal vasculature is rarely a complete barrier to visualization of the underlying sclera -Degree of pigmentation can normally vary. It can be so pigmented that its vasculature is barely discernible or it may be totally devoid of pigment -Epithelium pigmentation is determined by the same factors that govern coat pigmentation -GSD masked, while Husky very visible -In heavily pigmented breeds, melanin lies interspersed between the large vessels of the choroid Tapetum -Layer of reflective cells in the dorsal half of the fundus -Between the retinal pigmented epithelium (RPE) and the choroid -Reflectivity is dependent on the cell density, greater in the cat than the dog -Variations that are important are in extent (size) and degree of development -The overlying RPE is normally devoid of pigment so that the tapetum can be visualized -Normally the RPE gradually diminishes as it approaches the tapetum -The tapetum in turn thickens, results in a gradual change in color at its periphery Retina -Consists of 10 layers -Clinical purpose 2 layers -Outermost RPE and the neurosensory retina -Gross separation between the two is known as retinal detachment -RPE is monolayer lies next to the choroid on the ventral area -Normal variation in RPE determines if the choroid can be seen -Adjacent and attached to RPE is the semitransparent neurosensory retina, whose contribution to the normal fundus is the most subtle of all layers **Unlike the choroid and RPE, there are no normal variations to the sensory retina per se, variations of the vessels do occur** -Normally in dog 3-5 major retinal venues that radiate superiorly, nasally, and temporally from optic disc, producing venous circle -The cat has 3 paired retinal vessels never crossing the surface of the optic disc Optic disc -Cats: papilla varies little, being unmyelinated and characteristically circular -Darker in color than canine optic disc -Canine: marked variations in myelination and assume many shapes. Located within the tapetal fundus as well but may appear in the non-tapetal fundus of toy breeds

Answer 5

1. Can I get all parts of the fundus in focus simultaneously? 2. What is the general tapetal "sheen" over the whole fundus? 3. Are there any focal areas of unusual coloration within the fundus? 4. How do the retinal vessels appear? 5. How does the optic disc appear?

Answer 6

1. Visualization of choroidal vessels in the tapetal and non-tapetal fundus -Choroid thinning or thickening response to disease -Collie eye anomaly: thinning -Uvea is vascular tunic of the eye: choroidal thickening accompanies inflammation -Tapetal fundus discoloration and decreased reflectivity = choroid disease -Subretinal exudates = inflammation, possible detachment 2. Increased tapetal reflectivity -Suggest thinning/degeneration of the overlying retina -Decreased light absorption that accompanies retinal detachment/degeneration allows more light to be reflected back to the examiner from the tapetal surface 3. Diminished tapetal Reflectivity in active chorioretinitis -Occurs in active inflammation -Edema, exudation, retinal detachment 4. Retinal detachment -Sensory retina pathology: thinning or thickening -Retinal thinning: increased fundus reflectivity, fallow inflammatory, toxic and ischemic disease processes. -Retinal thickening: layers are folded, occurs in developmental disorders, or it may swell due to an influx of inflammatory cells, tumor cells, or fluid. -Sensory retina may respond to pathology by detachment form RPE. Occurs secondary to almost any ocular disease . Hypo-reflectivity in the area of detachment along with forward shift in the location of the retinal vessels -RPE changes are generally limited to affecting pigmentation -Increase or decrease in pigmentation are seen in hereditary retinal degenerations and secondary to inflammatory disease process. -Decreases in RPE pigmentation are readily seen in the non-tapetal fundus -Retinal blood vessels respond by change in size -Attenuated vessels Ddx: anemia, hypovolemia, retinal degeneration -Vascular enlargement less common Ddx: IOP disease, inflammation, hyper viscosity. -Retinal hemorrhage Ddx: systemic hypertension, anemia (pancytopenia) and clotting disorders -Hypoxic states: pink, lipemia animals or deeper red vessels 5. Optic disc -Responds by enlargement or decrease in size -Congenital or acquired changes -Numerous causes -Congenital hypoplesia or acquired optic atrophy following inflammatory disease, trauma or retinal degeneration will reduce the size of the papilla. -Enlarged papilla, neoplasia, inflammation or edema

Answer 7

1. Collie eye anomaly -Posterior segment abnormalities -Collie breed 80-85% affected -Autosomal Recessive -Shelter, Border Collie, Australian shepherd also have a congenital ocular anomaly similar to that of the Collie, but much low prevalence. -Diagnosed by 8 weeks of age -Bilateral ophthalmoscopic lesions, progressive and increasing in severity. C/S -Choroidal hypoplasia (pale area temporal to the optic disc) -Optic nerve and Scleral Colobomas -Retinal detachment/hemorrhage **Choroidal hypoplasia is the most common lesion encountered** -DNA test available 2. Retinal dysplasia -Embryologic developmental abnormality -Retinal layers are variably disorganized -The more severe dysplasia manifests as detachment or non-attachment. -Inherited from uterine infection (canine herpesvirus, feline panleukopenia) -Dx by 8 weeks of age -Many breed affected **Uncommon in the cat** **English Springer Spaniel: autosomal recessive trait** -Bedlington, American Cocker Spaniel, etc. C/S -Bilateral non-progressive, multifocal lesions appear as round or linear areas of discoloration in the tapetal fundus. -Lesions appear as hyper-reflective as the tapetum matures -Centers are pigmented **Functional vision is spared** -Blindness results when retinal tears or detachment accompany severe retinal disorganization -Cataracts in the Springer possible -Labradors, multifocal folds within the tapetal fundus. -Retinal detachment, corneal opacification, cataracts, vitreous degeneration, glaucoma (COL9A3 gene) -Short limb dwarfism **Samoyed: skeletal dysplasia also present** 3. Optic nerve hypoplasia 4. Generalized PRA (progressive retinal atrophy) -Inherited retinal degeneration in a variety of breeds 86 breeds reported C/S -Initial night blindness (nyctalopia) that progresses to total blindness -Older animals more common -Blindness < 1yo: Collie, Irish Otter, Cardigan Welsh corgi -Slower progression, blindness > 1yo: Gordon setter, Dachshund, Akita, Miniature schnauzer, Norwegian elkhound, Tibetan terrier. -Late onset, slow progression, Onset >2yo, Blindness 4+ yo: everything else, Golden retriever, Poodle, etc. Cats -Abyssinian: early onset, inherited autosomal dominant trait, onset 8-12 weeks old, blindness <1 yo. Also, can be late onset 4-6 yo blindness -Persian and Siamese also affected.

Answer 8

-Enrofloxacin in cats 5-20 mg/kg dose -Defect in transport protein causes accumulation of photo reactive fluroquinolones in the retina, exposure to UVA light = destructive free radicals and rapid retinal degeneration. -Risk: geriatric, hepatic or renal disease cats. C/S -Sudden loss of vision -Dilated pupils -Effect within a few days

Answer 9

-Systemic hypertension in cats -Systolic BP >180 mmHg >10 years old -Sudden or progressive blindness -Abnormal pupillary light reflex -Bilateral retinal detachment -Intra ocular hemorrhage Dogs -Hypertensive -Multifocal retinal hemorrhages Treatment -Amlodipine besylate daily -Can result in retinal re-attachment and return to vision in the cat Prognosis -The more chronic detachment the less likely return of vision -Risk of secondary glaucoma due to hemorrhage

Answer 10

SARD (Sudden acquired retinal degeneration) -Second most common, PRA is most common -Not reported in cats -Signalment: middle to older age. Females over represented. **Dachshunds and Schnauzer most represented breeds** C/S -Acute vision loss without signs of inflammation or discomfort -Unexplained mechanism -Loss of photoreceptor outer segments and abnormalities in the nuclear layer -No obvious fundic abnormalities initially -First observed 4-8 weeks after onset of blindness, subtle variation in tapetal reflectivity and retinal vessel segmentation -PU/PD, polyphagia, weight gain, panting consistent with Hyperadrenocorticism -Acute vision loss, abnormal pupillary reflex, optic neuritis -Normal PLR with cortical blindness **Electroretinography for definitive dx**

Answer 11

**Suggestive of systemic disease** -Infectious and/or neoplastic causes -Prognosis for vision is guarded 1. Viral: Distemper, Cat: FIP, FLV, FIV. 2. Bacterial: Brucellosis, Borreliosis, Cat: Bartonellosis, Tuberculosis 3. Fungal: Cat and dog: Blastomycosis, Cryptococcosis, Histoplasmosis, Coccidioidomycosis, Aspergillosis 4. Parasitic: Toxocara canis migrating larvae, Cat: Toxoplasma 5. Neoplastic: Lymphosarcoma, multiple myeloma, metastatic neoplasia -Optic neuritis: appears swollen and indistinct -Inflammation of the posterior segment **Unless vision is affected or other ocular tissue is concurrently inflamed the eye may appear unremarkable until ophthalmoscopic exam**

Answer 12

Active Chorioretinitis -Tapetal fundus hazy and gray -Edema, exudates may obscure tapetal reflection -Non tapetum area, edema and exudates appear gray or white obscuring RPE and choroid -Retinal vessels may appear hazy due to perivascular cellular cuffing -Hemorrhage may be present at various tissue levels -Retinal detachment may occur secondary to inflammation and or choroidal exudates

Answer 13

1. Canine Multifocal Retinopathy -Mastiff, Bullmastiffs, others -Early onset disease 3-6 months of age onset -C/S: acute, multifocal, serous retinal and RPE detachment. -Circular and gray-tan lesion. May regress, remain stationary or progress to degeneration 2. Acquired retinopathies -Chorioretinitis or posterior uveitis: Canine distemper virus infection

Answer 14

Optic neuritis -Swollen, indistinct optic disc, poorly defined margins, adjacent retinal hemorrhage and detachment. -If only the retrobulbar portion is affected, there may not be observable changes in the optic disc itself -Vision loss is typically acute -Affected pupils are widely dilated and PLR are absent or often delayed -Granulomatous Meningoencephalitis association -Ocular trauma, neoplasia -Most cases are idiopathic or immune-mediated -Less common in the cat Treatment -In the absence of an etiologic diagnosis: immunosuppressive corticoids for 14 days , tapered gradually until maintenance dose is determined -Alternatively immunosuppressive agents (azathioprine, cyclosporine) may be substituted -Prognosis for vision is poor, optic nerve atrophy sequela common

Answer 15

Disorders of the Lacrimal system

Answer 16

Iatrogenic causes -Etodolac, galliprant, various sulfa drugs, atropine -Surgical excision of nictitans gland "cherry eye" treatment Congenital -Immune mediated disease Infectious agents Toxic agents Neurologic reasons Inflammatory Functional Anatomy -3 layers -Mucin layer produced by conjunctival goblet cells -Tear film nourishes cornea and conjunctiva, lysosomes and immunoglobulins, lubrication -Blinking directs tears to medial canthus, collected in lacrimal lake, capillary action and passive pump mechanism leads to lacrimal puncta -Drain into a short caniculus, then lacrimal sac, then the nasolacrimal duct. -Epiphora: tear over production/flow 1. Deficiency in tear production 2. Tear excess 3. Abnormalities within the tear drainage system

Answer 17

-Loss of parasympathetic innervation -Dry nasal purulent discharge -Complete cessation of tear production C/S -Corneal ulceration -Often herpes virus infection -Nasal discharge is uncommon for a dry-eye dog -Ipsilateral dry nostril (XEROMYCTERIA) -Dry purulent discharge -Middle age females over represented **Otitis media/interna, trauma or surgery to the ear can be implicated** Treatment -Oral pilocarpine q6-8 hrs until return of normal production, then maintenance Feline sicca -Feline herpes virus implication

Answer 18

Keratoconjunctivitis Sicca (KCS) -Syndrome of progressive inflammation and degeneration of the cornea and conjunctiva resulting from inadequate tear production -Breed-related KCS is attributed to local immune mediated disease of the lacrimal glands, but congenital anomalies, infectious agents, and toxic, neurologic, inflammatory, and iatrogenic factors are all possibilities **Hallmark of KCS is the presence of copious mucoid or mucopurulent discharge** -Bacterial overgrowth Treatment -Topical antibacterial will eliminate discharge -Addressing the underlying cause for tear deficiency C/S -Dull cornea -Hyperemic conjunctiva -Superficial corneal vascularization and pigmentation will progress -Opacifying the cornea till blindness may occur -Secondary ulceration possible Dx -Schirmer tear test -Values < 10 SD mm/min is diagnostic (Normal values >21 mm/min dogs, cats >16 mm/min) -in brachycephalic breeds any values <15 SD mm/min is significant bc they are predisposed Treatment -Topical 0.2% cyclosporine and 0.02-0.03% tacrolimus applied BID, initially alone if sufficient -Antibiotics, topical lubricants, and/or steroids are generally indicated in the initial management -Neomycin-polymyxin -B-dexamethasone -Re evaluate in 6 weeks -Drugs above suppress immune injury to lacrimal glands -Artificial tears not equally effective in all patients, trial and error effort **Hyaluronic acid-base preparations are excellent for KCS** Mucin-deficient tear dysfunction Examples -I-drop Vet Plus -Optixcare Plus -Failure of BID cyclosporine or tacrolimus to improve condition or decrease clinical signs is an indication to substitute a more concentrated form of tear stimulant -Oral 2% pilocarpine BID Surgical treatment -Parotid duct transposition -Mineral deposition in cornea risk due to difference in composition between saliva and lacrimal fluid -Palpebral fissure can also be shortened in certain breeds to reduce exposure and drying

Answer 19

1. Secretory -Orbital glands -Nicitans glands -Meibomian glands -Conjunctival goblet cells 2. Distribution -Gravity -Eyelid blinking 3. Drainage -Nasolacrimal drainage -Lacrimal puncta -Lacrimal canaliculi -Lacrimal sac -Nasolacrimal duct Lacrimal and maxillary bones to empty via osmium in the ventrolateral floor of the nasal vestibule

Answer 20

Dx -Application of fluorescein dye to the corneal surface (Jones test) -Appearance in external nares -Longer than 4 minutes may be obstruction is present -Brachycephalics have longer transit times -If dye does not appear then there is a functional abnormality (e.g., punctual malposition), physical obstruction, or anomalous nasolacrimal opening in the posterior nasal cavity that causes the dye to drain into the nasopharynx rather than nasal cavity

Answer 21

-Inflammation of the lacrimal sac -Canaliculi and nasolacrimal duct affected -Persistent mucopurulent discharge concentrated in medial canthus -Foreign bodies are common culprits -Chronic KCS, conjunctivitis, nasolacrimal obstruction are causes -Bacterial infection involvement Dx -Bacterial culture -Cytology of exudate -Contrast Dacryocystorhinography -Radiographs, CT, MRI can help identify foreign body Therapy -Relief of obstruction -Removal of foreign body -Elimination of infection -Indwelling catheterization -Lacrimoscopy and Fluoroscopically guided stunting -Topical antibiotic solution -Aqueous corticosteroids for 14-21 dyas

Answer 22

-Abnormal tear flow down the face -Excessive tearing, obstruction, or tear film mucin deficiency Cause -Ocular irritation -Film mucin deficiency -IOP disorders such as uveitis Dx -Schimer test -Fluorescein dye test -TFBUT test

Answer 23

-If dye does not appear in the external nares and posterior drainage into the pharynx can not be documented, Nasolacrimal flushing is performed Nasolacrimal flushing -Topical anesthesia -The puncta appear as a slit like opening in the conductive located just inside the upper and lower eyelid margins ~5mm temporal to the medial canthus -The canaliculus then extends toward the medial canthus, parallel to the eyelid margin and just beneath the conjunctiva -22 g intravenous catheter or stainless steel cannula for nasolacrimal duct can be directed into the punctum -Sterile saline is flushed through the opposite punctum -The open punctum is often easier to cannulate since the lid margin can be everted -Some dogs may swallow which indicates successful passage through a more caudal opening in the nasal cavity -If the system is patent when flushed, functional cause of epiphora such as entropion and medial cantal trichiasis must be ruled out -If irrigation is not successful, then duct cannulation with a 0 to 2-0 monofilament nylon or praline may relive or bypass an obstruction -Cannulation may be maintained for 1-2 weeks by tying the suture material to the facial skin at either end **In many instances epiphora is primarily a cosmetic issue and surgical intervention is optional** Congenitally imperforate puncta and punctual stenosis -Careful incision with #11 scalpel blade over the punctum or by tenting and excising the overlying conjunctiva with a fine tenotomy scissor -If cannulation is not successful, extensive surgery may be required -Dacryocystomaxillorhinostomy -Orał tetracycline and doxycycline have been used to control facial staining -Oral Tylosin also used

Answer 24

-The tri-laminar film consists of a central aqueous layer sandwiched between outer lipid and inner mucin component -Premature break up of the tear can lead to dry spots in ocular surface, mimics KCS eventually C/S -Ocular discharge -Frequent blinking -Rubbing and conjunctival hyperemia -Cornea changes, roughening and loss of luster -Subtle superficial vascularization -Cavalier King Charles Spaniel predisposed Dx -Tear film break up time test -Drop of undiluted fluorescein dye applied to dorsal bulbar conjunctival surface -Cobalt blue light -"Holes" appear -Mucin deficient tear disperse in <5 sec (normal 20 seconds) -Schirmer test values are usually high Tx -Managing concurrent disease that could impact tear components -Disturbance of meibomian glands, infection, chronic skin disease all may interfere with tear film production/evaporation -Insufficient production can also reduce film stability -Chronic or immune mediated conjunctivitis may reduce goblet cell numbers **Cyclosporine or Tacrolimus** BID

Answer 25

-Cyclosporine -Tacrolimus -Hyaluronan-based lubricants

Answer 26

The cornea & Sclera

Answer 27

-4 anatomical layers -Outer epithelium: hydrophobic -Stroma: Hydrophilic, lamellae important to clarity -Descemet's membrane: innermost endothelium -Endothelium: one cell thick, hydrophobic, active ATPase pump. Factors of transparency 1. Avascular nature, limbal capillaries, tears, aqueous humor 2. Lamellar arrangement 3. State of dehydration "deturgescence" 4. Stroma hydrophilic, sandwiched between lipid barriers to prevent too much fluid 5. Endothelium regulates aqueous humor influx into the cornea Na/K ATPase pump = corneal clarity. 6. Hypertonicity of tears drawing fluid away from corneal surface

Answer 28

-Corneal surface: 300-400 times density of nerves than skin -Ophthalmic nerve branch, endings concentrated in the stroma Epithelium healing -Outermost layer -Starts within hours -Migration, mitosis, maturation = 7 days Stroma healing -Irregular fibers -Keratocytes, leukocytes -Reorientation 1-2 months -Infection = scarring, fibroblastic activity, delayed healing, vascularization Endothelial healing -Starts within hours -Descemet's membrane within 1-2 weeks -Aging: decrease endothelial function and cell density by 50% Corneal Response to Disease -Blue: edema -Red: vascularization -Gray: fibrosis or scarring -Black: melanosis -Yellow: Stromal infiltration of WBCs -White: accumulation of lipid or mineral within the cornea

Answer 29

Congenital Corneal Abnormalities Superficial Dermoid -Skin-like appendage on cornea/conjuntiva; irritation by associated hairs -More common in dog (St. Bernard, Dalmatian, Dachshund) than cat (Burmese) -Surgical excision by superficial keratectomy PPM-associated Deep Corneal Opacities 1. Association with persistent pupillary membranes, remnants of embryologic vascular system once covering the anterior lens 2. Fibrous extend from iris face to inner corneal endothelium 3. Non-progressive fibrosis, rare intermittent edema 4. No Tx indicated 5. Inherited: Basenji, Chow, Pembroke, Mastiff.

Answer 30

**Descemetocele: a deep corneal ulcer in which Descent's membrane is exposed due to complete loss of overlying epithelium and stroma** C/S -Iris prolapse -Staphyloma: outward protrusion of weakened corneal tissue, often lined by uveal tissue -"Melting" appearance to stroma -Anterior uveitis -Edema, cellular infiltrates, vessels in cornea -Non-specific signs of ocular pain Etiologies -Failure to identify/correct superficial ulcer -Infection -Excess collagenase activity -Innapropriate corticosteroid therapy Dx -"Bull's eye" pattern on Fluorescein test -Culture and sensitivity -Cytology of ulcer margin -Schirmer test -Leaking wound: Seidel's test positive, rivulets of bright green fluorescein dye extending from margin of lesion Tx -Direct therapy toward cause -Correct lid or tear abnormalities that may be contributing -Neomycin-polymyxin B-bacitracin solution, Cephalosporin compound -Gentemicin or Tobramycin or Fluoroquinolone (only for most serious cases) -Cephalosporin combined with amino glycoside or Fluoroquinolone -Topical autologous serum -Oral doxycycline -Tarsorrhaphy temporarily (or third eyelid flap) to prevent drying -Conjunctival graft if needed > half corneal thickness affected -Corneal-conjunctival transposition -Alleviate anterior uveitis: Systemic NSAIDs, 1% Atropine judiciously if mitotic, Topical corticosteroids/NSAIDs contraindicated

Answer 31

Ulcerative Keratitis (Corneal Ulceration) -Loss of epithelium with or without loss of corneal stroma General Signs -Blepharospasm (Spasmodic blinking), rubbing at eye, tearing, third eyelid protrusion -Corneal changes: loss of transparency due to edema, corneal contour changes Dx -Fluorescein dye test Etiology -Endogenous: lid abnormalities, exposure, inadequate tear volume -Exogenous: abrasion, foreign body, chemical burn Complication of healing -Infection: virus, bacteria, fungus -Defective epithelial basement membrane -Excessive collagenase activity: Pseudonyms and Streptococcus produce proteinases "Melts" stroma -Brachycephalic breeds: produce too much enzyme in response to corneal injury Superficial Ulcer, Uncomplicated Location -Central: lagophthalmos (incomplete closure of the eye), drying -Ventromedial: nicitans, foreign body -Dorsal: ectopic cilia -Ventrolateral: entropion Tx -Topical prophylactic antibiotic broad-spectrum -1% Atropine ointment to dilate pupil during exam -Elizabeth collar to prevent self-trauma **Avoid topical corticosteroids** -Inhibit migration, mitosis of epithelium -Decrease stroma fibroblastic proliferation -Inhibit antimicrobial response -Potentiate collagenase activity and stroll "melting" -Re-evaluate in 3-5 days -If no response to treatment: re-examine for foreign bodies, cytology, bacterial culture, evaluate ulcer margin for epithelial lipping

Answer 32

Superficial Ulcer - Recurrent Epithelial Erosion Dog -C/S: Diffusion of fluorescein defect beyond margin or lifting of epithelium at margin of ulcer -Either sex, BOXER (SCCED) most represented >5 yo Etiology -Epithelium fails to adhere to stroma -Unknown cause Tx -Mechanical debridement of epithelial lip with dry sterile cotton swab -Stromal polish using "Alger Brush" diamond bur -Broad-spectrum antibiotic -Hydrophilic contact lens bandage Prognosis -80% heal within 2 weeks -Recurrence likely -Keratotomy and repeat debridement may be necessary Cat C/S -Usually adults -Often precipitated by stress, steroids as for asthma **Pathognomonic DENDRITES (linear/branching/vermiform) or "geographic" appearance coalesce -Respiratory signs may appear Dx -Pathognomonic dendrites -Response to antiviral therapy -History of eye disease -Laboratory diagnosis are nor dependable Tx -Antiviral 1 week past resolution -Idoxuridine 0.5%, Cidofovir 0.5%, Ganciclovir 0.15%, Famciclovir, **oral L-lysine** -Stress reduction

Answer 33

1. Sepsis: yellow colored, cellular infiltrates, vascularization 2. Enzymatic tissue degradation: "melting"

Answer 34

-Brachycephalic breeds: produce too much enzyme in response to corneal injury

Answer 35

Corneal Lipidosis C/S -Crystalline, shiny, refractive "ground glass" appearance -Often centrally located Lipid dystrophy -Bilaterally symmetrical -Breeds, inherited: Siberian Husky, Collie, Sheltie, Cocker spaniel, Cavalier King Charles spaniel, etc. 62 breeds Lipid Degeneration -Unilateral or bilateral -Slowly progressive **Miniature Schnauzer** -Hyperlipemia, hypothyroidism, failure of fat metabolism (storage disease) association -Failure of cells to utilize lipids normally, secondary to pannus Tx -No specific treatment -Dietary consideration -Essential fatty acids -NSAIDs or corticosteroids if vascularization -Rarely causes vision loss or discomfort in cases of inheritable dystrophy Corneal Calcification Degeneration -Age-related -Geriatric patients -Hypercalcemia -Chronic keratitis C/S -Rough, gritty corneal deposits, snags cotton swabs -Dull, chalky appearance -Plaques may slough, causing rapidly progressive ulceration in these patients Tx -Debridement of superficial plaques with Alger brush -Topical 2% EDTA ointment to chelate mineral weeks to months process -Deep ulcers may require grafting to maintain corneal integrity

Answer 36

Feline Corneal Sequestrum C/S -Persians, Himalayans, Burmese most affected -Discomfort -Brown or black corneal plaque (not melanin) -Supreficial vascularization -Hespes virus infection, chronic ulceration, adnexal abnormalities, medial entropic, lagophthalmos/drying association Dx -Fluorescein stain uptake peripheral to sequesrum Tx -Spontaneous extrusion of plaque -Prophylactic antibacterial, antiviral -Bland lubricants -If painful, keratectomy to remove necrotic plaque -Excision followed by conjunctival or corneal graft may discourage recurrence Pigmentary Keratitis C/S -Non-specific corneal ulceration sign -Superficial pigmentation -Dogs: Boston terrier, Shih tzu, Pug -Superficial vascularization +/- -Association with lagophthalmos, facial folds, medial entropion, tear film instability Tx -Surgical correction of adnexal abnormalities, e.g., permanent partial tarsorrhaphy -Topical Cyclosporine to stabilize tear film -Topical corticosteroid to reduce vascularization (caution due to existing ulcer risk) -C/S often slowly progress despite therapy

Answer 37

>2yo -Bilateral always -Temporal quadrant affected initially, then nasal, inferior, superior. -Early plasma infiltration, sub epithelial vascularization, pigmentation -Nictitans infiltration concurrent Etiology -Presumed immune mediated -UV light -High altitudes -Fall/spring irritants Tx -Control not cure -1% prednisolone acetate or dexamethasone topical -4-6x daily for 2 weeks, monitor and then taper -Topical immune mediator: 0.2% Cyclosporine BID -Tacrolimus oitnment -Subconjunctival steroid -Protection from UV light -Client education **If untreated progresses to blindness**

Answer 38

Complication of healing -Infection: virus, bacteria, fungus -Defective epithelial basement membrane -Excessive collagenase activity: Pseudonyms and Streptococcus produce proteinases "Melts" stroma -Reactivation of Herpes virus -Bacterial opportunistic

Answer 39

Feline Eosinophilic Keratitis C/S -Disconfort -Pink to flesh colored plaque on corneal surface, temporal quadrant common -Corneal vascularization **Aberrant immune response, Herpes virus in 75% cases** Dx -C/S -Cytology: eosinophils, lymphocytes, plasma cells, mast cells, PMNs. Tx -Topical antiviral for herpes virus -Topical corticosteroid (1% prednisolone, dexamethasone) **Avoid if corneal ulcers are present** reactivation of virus -Oral MEGESTROL ACETATE: diabetes potential secondary, mammary hyperplasia/neoplasia -Triamcinolone SQ -Client education: controllable, 65% recurrence, seasonal exacerbations

Answer 40

Disorders of the Sclera Episcleritis - Nodular or diffuse -Proliferative keratoconjunctivitis, Collie granuloma -Presumed immune mediated -Young-middle age Collies, Cocker spaniels C/S -Nodular swelling, temporal limbus with corneal infiltration by lymphocytes, plasma cells, histiocytes, and fibroblasts Tx -Topical or intralesional corticosteroid therapy -Surgical excision or cryotherapy -Systemic immune modulation with tetracycline/niacinamide -Prednisone, or Azathioprine in refractory cases Pathology of Corneal Dystrophy or Degeneration -Breed disposition: Boston terrier, Chihuahua, etc. -Non-heritable degeneration -Endothelium degeneration resulting in progressive corneal edema -Non painful nearly stage -Later stage: fluid bullae breaks through epithelium to create punctate ulcers -Progressive to visual compromise Tx -Gundersen-type conjunctival flap in early stages to slow edema progression -5% NaCl ointment to discourage bullae formation -If recurrent ulceration, surgical referral, thermokeratoplasty, conjunctival flap -Transplantation of Descent's membrane (DSEK) from donor eye shows promise

Answer 41

Scleral Ectasia -Outward "bowing" of the scleral wall -Australian shepherds -Elevated blue-black area in anterior sclera -Collies: affects sclera surrounding optic disc -Merled dogs: part of multitude of congenital abnormalities -No medical or surgical Tx Epibular Melanoma -Slow growing tumor, benign, origination from pigmented limbus -German shepherd, Labrador, Gonden as early as 2yo

Answer 42

Disease of the anterior uvea

Answer 43

Uvea: vascular tunic of the eye Components -Iris -Iris sphincter muscle: ring of smooth muscle that encircles the pupil near its margin and results in MIOSIS or constriction of the pupil when stimulated. Innervated by parasympathetic system via terminal branches of the OCULOMOTOR nerve. -Iris dilator: weaker muscle, radially oriented in the posterior iris, innervated by SYMPATHETIC nerves and causes MYDRIASIS or dilation. -Ciliary body -Ciliary body muscle: is poorly developed in domestic animals, limited accommodative ability, PARASYMPATHETIC fibers from OCULOMOTOR nerve. -Choroid **Disorders of anterior uvea (iris, ciliary body) may represent primary ocular disorder or systemic disease association** Physiology/Function -Aqueous humor produced by ciliary processes epithelium -Fluid waste removal, nutritional component to cornea, clarity, exclusion of large protein molecules and cellular components -Mediation of light amount entering the eye PLR -Near vision adjustment/accommodation -Alter shape of lens

Answer 44

Persistent Pupillary Membrane -Persistent pupillarymembranes: developmental abnormality in the iris (iris collarette) -Tissue are remnants of an embryonic vascular system -Site of origin (iris collarette) helps to differentiate from inflammatory adhesions a.k.a SYNECHIA -Non-progressive opacities at the site of attachment -Basenji dog -No therapy indicated -Inherited in other breeds, Australian shepherd, Chows -Heterochromia iridis: normal variation in iris color -Iris atrophy: acquired problem, aging process, secondary from chronic intraocular disease, or unknown etiology. Ddx in patients with non-reponsive or poorly responsive pupils and dilated -Iris cysts: fluid-filled vesicles, free-floating. Golden retrievers pigmentary uveitis association. Unwarranted treatment otherwise. Inflammatory Adhesion - SYNECHIA -Adhesions of iris to lens = posterior synechia -Adhesions of iris to cornea = anterior synechia, less common

Answer 45

Anterior Uveitis C/S -Lacrimation: due to ocular pain -Blepharospasm: due to ocular pain -Photophobia: ocular discomfort when movement of the inflamed tissues as part of PLR -Enolphthalmos (retraction of the globe into the orbit): due to ocular pain -Lethargy, poor appetite: pronounced ocular pain -Hyperemia: Ciliary flush (engorgement of episcleral vessels) Conjunctival vessels dilation -Corneal opacification: edema due to endothelial changes, deep vascularization, keratin precipitates. Cats << Dogs -Cloudy aqueous: increased protein, leukocytes, hypopyon (in ventral chamber), KP's deposits on corneal endothelium = keratic precipitates. Turbidity due to increased protein content AQUEOUS FLARE. -Hypopyon: accumulation on the anterior chamber bottom -Poorly functional endothelium allows influx of fluid into stroma "paint brush" vessels around corneal circumference -Bloody = hyphen, blood in anterior chamber -Fibrin: gray, wispy appearance, can become a round clot -Lipid-laden aqueous: milky white -Iris changes: edema, hyperemia, miotic pupil. Due to dilation and increased permeability of the small blood vessels. -Decreased IOP -Pupillary constriction or MIOSIS: is a clinical sign of uveitis. Inflammatory mediators and tissue edema causes sluggish pupil. During examination it may not dilate with tropic amide, the sphincter becomes antagonist -Adhesions in iris: can trap behind the iris causing to bow forward, leading to PAS (peripheral anterior synechia) and altering aqueous outflow by obstruction of the iridocorneal angle and predisposing to IOP (glaucoma). **Inflammation of the ciliary body results in decreased function of its epithelium and a subsequent decrease in aqueous production** IOP decreases Consequences may include -Catarcts: secondary to synechia -Toxic lens epithelium, lens laxations due to degeneration of ciliary processes -Glaucoma -Hypotonic, non-functional globe, etc.

Answer 46

Tx Anti-inflammatory therapy 1. Corticosteroids -1% prednisolone or dexamethasone -Subconjunctival administration -Systemic therapy 2. NSAIDs: topicals or systemics caution when ulcers present -Carprofen or meloxicam Mydriatic-Cycloplegic Therapy 1. Atropine 1% -Parasympathetic agent -Decreases pain by relaxing bridal and ciliary muscle -Prevents adhesion of iris to lens (synechia) -Restores vascular permeability to normal -1-2 SIB, then decrease to maintain pupillary dilation as necessary -Ointment preparation minimizes side effects -Side effects: reducing tear production, ileus, predisposes to glaucoma, IOP elevation. **Contraindicated if glaucoma** -Tropicamide 1% shorter acting, safer if a must

Answer 47

Etiology of Anterior Uveitis Primary ocular disease: often unilateral. Blunt trauma, infection of extra ocular structures such as corneal ulcer, ocular neoplasia, malignant tumors such as melanoma. Lens-induced uveitis due to immune response to encapsulated protein. -Phacolytic uveitis: inflammation that leads to cataracts from lens induced uveitis -Phacoclastic uveitis: cat scratch injuries, traumatic rupture of lens -Idiopathic disease Secondary consequence of systemic disease -Metabolic disorder alters vascular permeability, hyphen or flare -Hypertension and renal failure, choroid disease -Metastatic tumors -Infectious diseases -Viral: canine adenovirus-1 "hepatitis blue eye". Feline: FLV, FIP, FIV. -Bacterial: secondary to pyometra, dental abscessation, osteomyelitis). Lepto, brucellosis, bacterial endocarditis, neonatal septicemia -Fungal: Blastomycosis, histoplasmosis, etc. -Parasitic: Aberrant Dirofilaria -Protozoan: Enrlichiosis and RMSF. Riccketsial disease, doxycycline -Immune mediated: Akita, Siberian husky, Malamute Dx -C/S: red, cloudiness, corneal disease. -Conjunctivitis -Glaucoma -Recognition of redness and cloudiness is more challenging in the cat due to limited visualization of the sclera and a cornea that resists edema -PE assessment of organ systems

Answer 48

1. Anterior capsule 2. Lens epithelium 3. Anterior cortex 4. Nucleus 5. Posterior cortex 6. Posterios capsule

Answer 49

1. Vitreous posteriorly 2. Iris anteriorly 3. Lens zones circumferentially, extending from ciliary processes to lens equator: ciliary muscles shift lens forward to focus near objects, backward relaxes it, far objects.

Answer 50

-Lens protein is immunologically privileged due to protection from immune system via semi-permeable capsule -Minor immune tolerance due to constant leakage of small amounts of lens protein -Rapid protein leakage (as in diabetics) and or chronic cataracts formation influences permeability and capsule damage leads to immune mediated inflammation Metabolism -Glucose from aqueous provides most lens energy requirements -Anaerobic glycolysis is the major pathway of glucose metabolism

Answer 51

Lens Aging Nuclear sclerosis -Normal change resulting in increased central lens density -6yo starts -Opacity appears translucent, smoky pearl dropped into the center of the lens -Fundus structures still visible, tapetum reflection still visible -Best evaluated with retroillumination dilated pupil -Smooth clear nuclear boundary and clear peripheral cortex can be visualized

Answer 52

Cataract: opacity of the lens, most commonly inherited abnormality. Cats more common due to chronic uveitis Age of Onset 1. Congenital 2. Juvenile 3. Senile: 6yo or older Location 1. Capsular 2. Subcapsular 3. Cortical 4. Nuclear 5. Suture-related Degree of maturation 1. Incipient -Early focal opacity -Equatorial vacuoles and lens fibers swelling 2. Immature -More extensive opacity -Tapetal reflection still visible -Lens swelling, uveitis and leakage may be present 3. Mature -Positive PLR (cataracts alone will not cause loss of PLR) -Totally opaque lens -Optic nerve healthy 4. Hypermature -Liquefaction produces some degree of cortical clearing -Phacolytic uveitis -Cortex completely liquified

Answer 53

Lens Aging Nuclear sclerosis -Normal change resulting in increased central lens density -6yo starts -Opacity appears translucent, smoky pearl dropped into the center of the lens -Fundus structures still visible, tapetum reflection still visible -Best evaluated with retroillumination dilated pupil -Smooth clear nuclear boundary and clear peripheral cortex can be visualized Cataracts -Obscures tapetal reflection Etiology 1. Inherited 2. Developmental: PPM (Persistent pupillary membranes), PHPV (Persistent hyperplastic primary vitreous) 3. Traumatic 4. Metabolic 5. Toxic 6. Nutritional 7. Inflammatory: specially in the cat 8. Idiopathic

Answer 54

Diabetes mellitus -Hyperglycemia overwhelms the normal metabolic pathway in the lens -Production of non-soluble sugar alcohol via aldose reductase pathway creates osmotic gradient with influx of fluid into lens -Disruption of lens fiber membranes leads to protein precipitation and cataract formation

Answer 55

Cataract Surgery = elective procedure -Major health problems should be addressed prior to surgery -Complete eye exam to identify ocular diseases that would complicate or obviate the need for cataract surgery for example: -Keratitis -Inadequate tear production -Uveitis -Glaucoma -Lens subluxation -Retinal disease -Active infection/inflammation (otitis, dermatitis, dental disease, cystitis) Complications of cataract surgery -Anterior uveitis -Ruptured posterior capsule?vitreous herniation -Hyphema -Shallow anterior chamber -Wound dehiscence -Infection -Glaucoma -Retinal detachment

Answer 56

Lens Displacement Subluxation -Remains in patellar fossa -Some zones remained attached Luxation -Complete displacement from patellar fossa -Anterior or posterior luxation **Miotic agents such as Latanoprost, Pilocarpine, and Demecarium are contraindicated bc they exacerbate the pupillary blockade**

Answer 57

Diseases of the Orbit

Answer 58

Primary C/S -Exophthalmos -Enophthalmos -Strabismus (involuntary fixed deviation of the globe from its central axis) Secondary -Ocular discharge -Lagophthalmos (inability to completely close the eyelids) -Conjunctival swelling -Corneal disease -Optic nerve dysfunction -Fundus abnormalities -Retina hemorrhage, etc.

Answer 59

Exophthalmos -Can be caused by a discrete space-occupying orbital mass, neoplasm, abscess, zygomatic mucocele, or vascular anomaly -Brachycephalic is breed related normally present

Answer 60

Retrobulbar Neoplasia -Slowly progressive -Non painful **Mast cell tumors, orbital lymphoma are painful and rapid onset** -Unilateral exophthalmos -Periocular swelling, exposure keratitis, retinal detachment may be present -91% of Feline tumors are malignant and 90% of canine are malignant -Dog average age 8yo, Cats 8-9 yo -Survival 10 mts Dog -Optic nerve meningiomas -Fibrosarcoma -Osteosarcoma Cats -Malignant melanoma -Lymphosarcoma -Osteosarcoma -SCC Dx -History -Radiographs -Ultrasound -CT -MRI -Cytology -FNA Tx -Exenteration of the orbit -All orbit contents are excised -Ancilliary radiation and chemotherapy Retrobulbar Inflammation -Cellulitis/Abscessation/Myosistis -Acute signs -Considerable pain -Fever often seen -Leukocytosis may be evident on CBC -Tooth root abscess most common cause -Penetration of foreign bodies through soft palate, skin or conjunctiva into orbit Dx -Orbital ultrasound -Oral exam -Dental radiograph Tx -Surgical drainage through oral mucosa -Never close the tips of hemostat while instrument still in orbit as it can damage optic nerve -Culture and sensitivity indicated -Wound can heal by second intention -Amoxicillin/Clavulanic acid orally

Answer 61

-Loss of smooth muscle tone in the periorbita -Due to sympathetic denervation -Enophthalmos and protrusion of the third eyelid -Ptosis (drooping of the upper lid) -Relative miosis when compared to the opposite eye

Answer 62

Masticatory myositis -Exophthalmos uni or bilateral -Pain upon opening the mouth -Shetland sheepdogs, GSD, Golden retrievers, Weimaraners most affected 3yo most common C/S -Acute inflammation 10-21 days -Eyelid edema -Protrusion of third eyelid -Conjunctival hyperemia Tx -Immunosuppressive corticosteroids -Azathioprine may also be effective Extraocular Polymyositis -Immune mediated myopathy -Females and 7-10 mts old most affected -Bilateral mostly, not symmetrical -Acute onset of exophthalmos -Chemosis -360 degrees scleral show and absence of third eyelid protrusion -Pain not common -Vision occasionally compromised -Psychological stress association Cystic Orbital Disease -Exophthalmos -Cysts arising from epithelial or glandular tissue -Mucoceles can also develop -Firm, smooth, fluctuant cysts -Ultrasound hupoechoic and well delineated -Tx: surgical resection curative

Answer 63

Proptosis of the Globe -Traumatic displacement from the orbit TRUE EMERGENCY -Brachycephalic breeds predisposed -Prognosis for return to vision is guarded -Temporary tarsorrhaphy -Antibiotic ointment -Systemic corticosteroids -Sequela: strabismus, lagopththalmos, decreased tear production, corneal ulceration

Answer 64

-Deviation of the globe from its central axis -Common in brachycephalic breed -Develops in response to space-occupying orbital lesions, rupture of the extra ocular muscles, and abnormalities of the CNIII, IV, VI. -Ventrolateral deviation occurs in hydrocephalic animals with enlarged cranial cavity -Siamese cats may appear crossed-eyed

Answer 65

Enucleation -Removal of the eye, eyelid margins, conjunctiva, and third eyelid -Silicone sphere put into orbit -Indications: neoplasia, catastrophic trauma, chronic intractable glaucoma, severe intraocular inflammation unresponsive to therapy -Cats have short optic nerve, careful surgery or blindness in remaining eye Exenteration -Removal of all orbital contents -Indicated for orbital neoplasia Evisceration -Removal of all intraocular contents -Sclera incised -Silicone sphere implanted -Indicated for cosmetic treatment of end-stage glaucoma **Always submit tissue for histopathology**

Answer 66

Causes -Ocular pain -Microphthalmia -Phthisis bulbs -Horner's syndrome -Dehydration -Loss of orbital fat -Muscle atrophy -Collapsed globe -Conformational exophthalmos in dolichocephalic breeds Tx -Seldom indicated

Answer 67

-Abnormally elevated IOP incompatible with normal ocular physiology and vision -Devastating effect on optic nerve, death of retinal ganglion cells at their axons -Common cause of blindness in companion animals -Primarily an inherited disorder in dogs -Cats usually complication of chronic uveitis

Answer 68

Normal IOP: 10-20 mmHg -Decreased in outflow of aqueous humor and subsequent outflow from the eye -Usually prior to (pupil) iridocorneal angle or within it -Carbonic anhydrase enzyme active in secretory process of ciliary body epithelium aqueous humor production. It can be pharmacologically modified to reduce aqueous production -Normally aqueous exits through the iridocorneal angle from the anterior chamber -Ultimately entering the systemic circulation through the trabecular veins, sclera venous plexus, and vortex veins -Prostaglandin analogues that increase uveoscleral outflow in the dog present a major breakthrough in glaucoma control in recent years, but not effective in the cat

Answer 69

Acute Canine Glaucoma C/S -Subtle and highly variable -Mild conjunctival vascular enlargement -Increased tearing -Variable pain -Photophobia **Important to measure IOP on any patient with red eye** -Easy to miss signs of glaucoma Advanced disease -Ocular pain due to trigeminal neuralgia -Blepharospasm -Nicitans protrusion -Excessive tearing -Epsiscleral and conjunctival vessels congestion, passive process due to compromised venous outflow -Corneal edema, pressure affects the endothelium and CN V nerve endings -Pupillary dilation, muscular paresis due to pressure on retina/optic nerve -Elevated IOP Chronic -Scleral thinning -Decreased evidence of ocular pain -Haab's striae - breaks or stretch marks in Descemet's membrane -Iris degeneration -Fundus lesions

Answer 70

Dx -Tonometry -Ophthalmology of retina, optic disc -Gonioscopy to evaluate gross appearance of iridocorneal angle. Helps differentiate between primary and secondary glaucoma Primary glaucoma -No concurrent ocular disease or injury -Breed-related, inherited -Bilateral but one eye more affected than the other. -Second eye affected within 8-12 mts if no treatment -Identification of the abnormal angle substantiates need for prophylactic therapy of the second eye Gonioscopic - Iridocorneal angle 1. Open angle glaucoma: normal angle; Beagle 2. Narrow angle: decreased width of angle; Crocker spaniel 3. Pectinate ligament dysplasia (goniodysgenesis): abnormal pectinate formation, characterized by broad sheets of tissue with few flow holes; Basset hound Secondary Glaucoma -IOP sequela to other ocular disease or injury -Causes: lens luxation, trauma, inflammation, neoplasia **Pupillary blockage by lens responsible for IOP increase** -Anterior uveitis produces adhesions of iris to cornea, obstructing flow through the iridocorneal angle -Tumors invade and cause secondary inflammation, adhesions Therapy 1. Reverse IOP increase a. Medical: stabilize within 24-48 hours b. Surgical c. Combination Drugs MOA 1. Promotes aqueous outflow (usually with miosis) 2. Dehydrate the vitreous 3. Decrease aqueous production -Topical less potent but less side effects than systemic -Dogs tolerate better than cats -Remission of primary glaucoma, later additional alternate drugs -Always aim for synergistic action -Human drugs do not predictably work on dogs or cats Neuroprotective agents -Systemic calcium channel blockers (Amlodipine besylate) -Systemic corticosteroids to combat oxygen free radicals **Prophylactic treatment of second eye is imperative** -Topical Carbonic anhydrase inhibitor (Dorzolamide or Brinzolamide) for prophylactic second eye care -Topical Demecarium bromide solution combined with SID steroid **Refer immediately to ophthalmologist, do not wait** Primary Narrow Angle Glaucoma, Medical Tx -2% Dorzolamide topically -Latanoprost topically -If no improvement: repeat Latanoprost add mannitol, recheck -If no improvement: refer If improved after 2% dorzolamide -Re-evaluate in 1 hour -Dorzolamide q8 hrs -Latanoprost q 12 hrs -Recheck IOP q 4-6 hors -If stable: continue both, treat second eye prophylactically, refer for surgical evaluation

Answer 71

-Rarely diagnose in cats -Signs present in dogs not present in cats -Most common complain is increased eye size -Cloudy eye appearance -Increased pupil size -Usually blind by the time of evaluation -90% secondary glaucoma associated with chronic anterior uveitis -Treatment defers from primary glaucoma

Exam 4 Flashcards

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