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82 Cards in this Set

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What 3 structures normally atrophy around birth?
hyaloid artery
pupillary membrane
tissue covering iridocorneal angle
What are 2 conditions of defective organogenesis of the eye?
microphthalmia: congenitally small eye (horses, cattle)

coloboma: a notch-like defect resulting from incomplete fusion of lips of embryonic fissure
What is persistent pupillary membrane?
failure of pupillary membrane to atrophy around time of birth

iris strands go to lens

very common & usually subclinical

heritable in Basenji, Collies, Corgis; spontaneous in most dogs
What is goniodysgenesis?
maldevelopment of iridocorneal angle

can lead to 2º glaucoma
What are some conditions resulting from anomalies of surface ectoderm?
dermoid: piece of skin (often haired) stuck to cornea or conjunctiva (choristoma)

microphakia, lenticonus, lentiglobus: shape & size abnormalities of lens

congenital cataract
macropalepbral fissure

a. signalment
b. predisposes to..
c. concurrent facial features
d. tx
a. familiar trait in brachycephalic breeds
b. lagophthalmos (inability to completely close eyelids) & corneal ulceration
c. shallow orbits, large eyelid openings, nasal fold hair that can rub on surface of eye
d. medial canthoplasty
disthichiasis

a. definition
b. predisposes to..
c. tx
a. cilia emerging from a dysplastic gland, usually meibomian gland
b. cause corneal & conjunctival irritation/ulceration if they contact globe (often asymptomatic)
c. cryosurgery
entropion*

a. definition
b. signalment
c. predisposes to..
a. inversion of lid margin & periocular skin
b. -1º entropion seen in breeds w/ excess facial skin (ex. Shar Pei)
-common in newborn sheep, horses d/t tissue edema (transient)
c. contact of facial hair w/ globe --> conjunctival & corneal irritation
meibomitis (internal Hordeolum)*

a. defintion
b. species affected
c. etiology
a. suppurative inflammation of meibomian glands
b. dogs, cats.
c. usually d/t Staph infection & often assoc. w/ generalized dermatoses
chalazion*

a. definition
b. gross appearance
c. cause
a. granulomatous inflammatory rxn to retained meibomian gland secretions
b. firm, yellow mass visible thru palpebral conjunctiva
c. obstruction of glands d/t adenoma or inflammation
blepharitis

a. defintion
b. etiologies
a. inflammation of eyelid skin
b. Staph (dogs), pox virus (birds), dermatophytes, Demodex (dogs), Habronema (horses), allergic or immune mediated (ocular manifestation of atopy)
meiobomian gland adenoma*

a. signalment
b. biolgic behavior
c. tx
a. very common in older dogs
b. benign, slow growing
c. cryosurgery preferred (will recur w/ excision)
eyelid melanoma*

a. species affected
b. biologic behavior
a. dog
b. benign
What is the biologic behavior of eyelid SCC in cat?*
malignant: usually fast growing & locally invasive, but not metastatic
What are the responses to injury of conjunctiva?*
hyperemia
chemosis (edema)
ocular discharge (serous, mucoid, purulent)
follicle formation (lymphoid tissue: nonspecific finding assoc. w/ chronic irritation)
conjunctivitis*

a. etiology in dogs
b. etiology in horses
c. etiology in cats
a. often secondary to other ocular dz
bacteria (bacteria found in conjunctival sac of normal eyes --> conjunctivitis occurs when an injury alters normal homeostasis & allows bacteria to proliferate), allergic, systemic viral dz (distemper), rickettsial

b. often secondary to other ocular dz
bacterial, allergic, parasitic (Habronema, Onchocerca)

c. usually d/t primary pathogen
feline herpes virus-1, Chlamydia felis, Mycoplasma
episcleritis*

a. presumed etiology
b. 2 types
c. tx
a. idiopathic, presumed immune mediated inflammation of sclera
b. simple, diffuse episcleritis: hyperemic & engorged episcleral & conjunctival vessels, often perilimbal corneal edema

nodular granulomatous episclerokeratitis (NGE): nodule formation on sclera w/ fleshy red apperance
c. topical steroids
episcleral melanocytoma (limbal melanoma)*

a. species affected
b. biologic behavior
a. common in dog & cat
b. benign, generally slow growing
can invade cornea, iridocorneal angle late in course
prolapse of nictitans gland (cherry eye)*

a. cause
b. tx
a. congenital laxity in CT anchoring gland to cartilage at base of nictitans
b. surgical replacement (removal predisposes to dry eye)
What is the common result of lesions of the lacrimal system?*
obstruction to normal tear drainage & epiphora (excessive tearing)
imperforate lower puncta

a. species affected
b. cause
a. congenital in dogs
b. born w/o opening to lower puncta b/c it’s covered w/ sheet of tissue that normally atrophies --> epiphora
dacryoadenitis*

a. definition
b. results if chronic
c. etiology in dogs
d. etiology in cats
e. etiology in rats
a. inflammation of lacrimal gland
b. atrophy, fibrosis, & squamous metaplasia of affected glands w/ resultant loss of secretory function
c. presumed immune mediated
d. FHV-1
e. coronavirus
keratoconjunctivitis sicca (KCS)

a. species affected
b. causes
c. effects
d. tx
a. common in certain dog breeds
b. presumed immune mediated destruction of lacrimal tissue
c. fibrosis of lacrimal glands from dacryoadenitis
loss of aqueous portion of protective tear film --> 2º effects on cornea & conjunctiva
painful, can lead to blindness if chronic & severe
c. cyclosporine
What is the major indicator of corneal dz?
loss of transparency
What is the response of the cornea to chronic injury?
undergoes metaplasia to become scleral-like tissue & can respond w/ a full range of inflammatory responses
What are some responses to corneal injury?
ulceration
edema
vascularization
inflammatory cell infiltrate
pigmentation
fibrosis (scarring)
metabolic infiltrate
What is corneal ulceration?
loss of corneal epithelium w/ or w/o stromal loss

initiated by trauma or irritation

complicated by bacterial or fungal infection
What causes corneal edema?
implies either epithelial or endothelial damage or loss

whitish to light blue speckled appearance
corneal vascularization

a. superficial insult
b. deep insult
will vascularize at depth of lesion (helps localize dz process)

a. superficial corneal vessels that originate from conjunctival vessels (branching, cross limbus)
b. deep corneal vessels that originate from episcleral vessels (straight, “brush border”, cannot be seen crossing limbus)
What is the oculopupillary reflex?
CN V --> brain stem --> CN III --> ciliary body & iris sphincter m.
What is the axonal reflex?
involves prodromic & antidromic axoplasmic flow along CN V from cornea to iris & ciliary body
What are the responses of adjacent tissues to corneal injury?
conjunctival vascular injection & congestion

miosis & ciliary body spasm: oculopupillary & axonal reflexes
What are the characteristics of corneal wound healing?*
epithelial: sliding of cells to cover ulcer, followed by mitosis (rapid rate: 1 mm/day)

stromal: slow & incomplete, new collagen produced generally NOT transparent
chronic superficial keratitis

a. other name
b. cause
c. aggravated by...
d. tx
a. German Shepherd pannus
b. presumed immune mediated rxn to altered corneal antigen
c. UV light
d. topical steroids
What is corneal stromal dystrophy?
hereditary stromal lipid deposits (occurs in many dog breeds)

occurs as result of a focal alteration in corneal lipid metabolism

usually just a cosmetic issue
corneal endothelial degeneration

a. cause
b. signalment
c. effects
a. age related ↓ in endothelial cell density 2º to endothelial cell necrosis

b. common in older dogs or middle aged Boston terrier, Chihuahua, Dachshund

c. progressive corneal edema results: endothelial cells pump water from cornea into anterior chamber & keep cornea “dehydrated” & transparent
What is pannus?
corneal scarring
corneal sequestrum

a. other names
b. signalment
c. may be sequelae to..
d. gross lesion
a. corneal nigrum, necrotizing keratitis
b. only affects cats (predilection for Persian, Siamese, Himalayan)
c. FHV-1 keratitis
d. central dark pigmented lesion: almost pathognomonic
What is the sequence of events in ulcerative keratitis?
epithelial loss

stromal loss: considered to indicate microbial infection

descemetocele: corneal ulcer that has extended to depth of Descemet’s membrane

corneal perforation: usually evident by iris tissue & fibrin w/in corneal wound (anterior synechia)
What are the most common etiologies of ulcerative keratitis in:

a. dog
b. cat
c. horse
d. cow
e. sheep
f. goat
a. endogenous trauma (ex. eyelash disorders, lagophthalmos, KCS, etc.), can initiate 2º microbial infection
b. FHV-1
c. exogenous trauma w/ 2º bacterial or fungal infection
d. Moraxella bovis
e. Chlamydia
f. Mycoplasma
refractory superficial corneal ulcers

a. other names
b. signalment
c. cause
a. Boxer ulcers, indolent ulcers
b. older dogs (Boxers), horses
c. failure of normal wound healing d/t epithelial cell non-adherence
generally an epithelial ulcer w/ loose rim of non-adherent epithelium
cataract

a. definition
b. species affected
c. pathogenesis
a. any opacity in lens
b. most common in dogs, less common in horses, rare in cats
c. exposure to wide variety of physical or chemical insults, derangement in lens metabolism
stages of cataract development
incipient: early cataract
-detect using retroillumination: foci of tapetal reflection blocked out

immature

mature: entire lens opaque (no tapetal reflection)

hypermature: lens fibers liquefy, can leak out basement mem (lens capsule) into anterior chamber --> inflammation (lens induced uveitis)
What are some etiologies of cataract formation?
-genetic** (hereditary, familial): most common etiology of cataracts in dogs (~80%); usually adult onset: b’twn 2-6 years old

-postinflammatory: 2º to byproducts of uveal inflammation or trauma to lens capsule, w/ derangement of lens fibers (most common cause in cats & horses)

-diabetes mellitus (esp. dogs)

-nutritional in puppies, kittens

- secondary to retinal degeneration: by products of retinal degeneration (dialdehydes) diffuse thru vitreous to perturb lens metabolism
What is the pathogenesis of cataracts associated w/ diabetes mellitus?
glucose levels in eye ↑ d/t DM --> hexokinase (regulatory enzyme) becomes saturated --> glucose accumulates in lens & begins to be metabolized thru sorbitol pathway via aldose reductase --> sorbitol & fructose accumulate w/in cells of lens since they penetrate cell mems poorly --> intracellular accumulation of solutes & hypertonicity --> accumulation of water w/in lens fibers --> swelling & rupture of lens fibers --> formation of vacuoles in lens cortices --> this continues until entire lens becomes cataractous
lenticular (nuclear) sclerosis

a. definition
b. signalment
c. distinguishing from catarct
d. distinguishing from corneal edema
a. progressive lens fiber formation & internal compression of older lens fibers
b. common in old dogs: gray/smoky, translucent lens
c. doesn't interfere w/ tapetal reflection like a cataract does
d. can see iris w/ nuclear sclerosis, can’t w/ corneal edema

in general, doesn't interfere w/ vision
lens luxation & subluxation

a. pathogenesis
b. normal direction of displacement
c. normal sequelae
d. etiologies
e. clinical sign
f. tx
a. involves damage to lens zonules
b. ventral
c. secondary glaucoma
d. primary*: familial tendency in terrier breeds
2º to chronic uveitis: cats, horses
idiopathic: age-related degeneration of zonules
trauma: uncommon
e. aphakic crescent: portion of pupil NOT covered by lens (diagnostic for lens displacement)
f. remove lens
glaucoma

a. definiton
b. species affected
c. 1st tissues to be damaged by increased IOP
d. pathogenesis
a. pathophysiologic state caused by a sustained ↑ in IOP beyond that compatible w/ normal ocular function
b. one of most common causes of blindness in dogs, less common in cats & horses
c. neural retina, optic nerve
d. obstruction to flow of aqueous humor anywhere along pathway
primary glaucoma

a. cause
b. types
c. px
a. abnormality of iridocorneal angle --> ↓ outflow
b. narrow or closed angle: most common type of 1º glaucoma in dog; genetically determined, age related narrowing of iridocorneal angle

goniodysgenesis: glaucoma that occurs 2º to abnormal development of iridocorneal angle; instead of pectinate fibers, angle covered w/ broad band of tissue w/ few to no flow holes

open angle (rare): obstruction to outflow occurs deep to actual iridocorneal angle
c. bilateral, progressive dz w/ guarded long term px for vision
causes of secondary glaucoma
occurs secondary to some other abnormality

- anterior uveitis: #1 cause in cats, horses; swelling of uveal tissues in angle; extensive posterior synechia

-lens luxation: pupillary block; vitreous in angle

-other: intumescent cataract, introcular neoplasia, hyphema
lesions associated with glaucoma
corneal edema
conjunctival & scleral vascular stasis (hyperemia)
paralysis of iris musculature: dilated, non-responsive pupil
uveal atrophy
retinal atrophy: esp. inner retina or ganglion cell layer
optic nerve “cupping” or posterior bowing
buphthalmia: enlarged globe (hallmark of chronic glaucoma)
corneal scarring from inability to blink eyelids (from buphthalmia)
What structures make up the

a. anterior uvea?
b. posterior uvea?
a. iris, ciliary body
b. choroid
iris atrophy

a. signalment
b. dx
a. idiopathic degeneration of iris seen in old dogs & cats
b. pilocarpine fails to constrict pupil; incomplete pupillary light reflex
iris cysts

a. signalment
b. cause
c. distinguishing from iris melanoma
a. common in old dogs, esp. Great Danes, Goldens, Boston terriers (usually asymptomatic)
b. multifocal cystic separation of posterior iris epi, or, rarely, ciliary body epi
c. cysts are translucent (can see some of tapetal reflection)
iris melanosis

a. definition
b. signalment
c. monitor for?
a. accumulation of normal melanocytes in iris
b. benign condition in old dogs
c. transformation to malignancy
What is..

a. endophthalmitis?
b. panophthalmitis?
a. inflammation of uvea, retina, & ocular cavities (all internal eye structures involved)

b. inflammation of all ocular structures
What clinical findings are associated w/ anterior uveitis?
pain
redness
swelling of iris
loss of function: ocular hypotony (dec. IOP), breakdown of blood-ocular barrier --> progressive exudate accumulation in anterior chamber (aqueous flare, fibrin, keratic precipitates, hypopyon, hyphema), corneal edema, poor response to topical mydriatic agent
What are some etiologies of anterior uveitis?
trauma
introcular sx
secondary to corneal or scleral dz
systemic microbial infection: histoplasmosis, brucellosis, toxoplasmosis, ehrlichiosis, canine infectious hepatitis, FIP, FelV, etc.
immune mediated: lens induced, canine adenovirus, uveodermatologic syndrome, chronic idiopathic
neoplasia
What are the 2 types of lens induced uveitis?
phacolytic (phacotoxic) uveitis: mild anterior uveitis resulting from release of lens proteins from an intact lens capsule; common w/ hypermature cataracts in dogs

phacoclastic uveitis: severe anterior uveitis rsulting from disruption of lens capsule --> massive release of lens proteins into ocular tissues (usually d/t penetrating trauma)
uveodermatologic syndrome

a. another name
b. signalment
c. cause
d. effects
e. tx
f. px
a. VKH-like dz
b. Arctic Circle dog breeds (ex. Akita, Siberian Husky)
c. caused by immune mediated destruction of melanocyte containing tissue (ex. eyes, skin)
d. severe panuveitis w/ retinal detachment & dermal depigmentation
e. systemic immunosuppressive agents & topical anti-inflammatories
f. poor for vision
chronic idiopathic uveitis

a. cause
b. tx
50% of anterior uveitis in dogs, 70% in cats, 90% in horses (equine recurrent uveitis)

a. initial injury to blood-ocular barrier (from any insult) --> immune mediated factors are thought to contribute to most cases
b. anti-inflammatory therapy
What is the most common anterior uveal tumor in dogs, cats, & horses?

What is its biologic behavior?
melanoma

usually benign, slow growing, & rare to metastasize in dogs & cats
diffuse iris melanoma

a. species affected
b. biologic behavior
c. tx
a. cats
b. late in course, presents as a change in iris color & 2º glaucoma; diffuse infiltration of anterior uveal tract (progresses slowly); high metastatic potential (50-70%)
c. enucleation
What is the most common secondary tumor of the uvea?

What might it look like grossly?
LSA

may look grossly like anterior uveitis: always have LSA as a ddx: thickened iris +/- cellular accumulation +/- mass lesion
What is the ocular fundus & what are its layers?
posterior aspect of eye as viewed ophthalmoscopically

sclera
choroid: tapetum, pigment
retinal pigment epithelium (RPE): non-tapetal fundus, tapetal fundus
sensory retina: retinal vasculature
What is the area centralis?
portion of fundus w/ high concentration of photoreceptors (area of most acute vision)

found temporal (lateral) to optic disc: relatively avascular area
thinning or absence of retina

a. causes
b. effect on tapetal fundus
a. atrophy, degeneration
b. hyperreflectivity (focal or diffuse); if assoc. w/ central dark area: tapetal necrosis or RPE hyperpigmentation
thickening of retina

a. causes
b. effect on tapetal fundus
a. dysplasia, inflammation, edema, neoplasia
b. hyporeflectivity (focal or diffuse)
retinal detachment

a. defintion
b. mechanisms
c. causes
d. effects on tapetal fundus
a. separation b’twn RPE & sensory retina
b.
traction from vitreous: bleeding in vitreous (least common)

subretinal fluid accumulation: exudates, edema, blood, liquid vitreous (most common); inflammatory cells push retina off attachment

rhegmatogenous: tear in retina, vitreous dissects into subretinal space --> lifts sensory retina off attachment
c. trauma, neoplasia, inflammation, vascular & hematologic changes, following intraocular sx, degenerative changes in vitreous (age related)
d. hyporeflectivity, whitish discoloration in non-tapetal fundus, folding or retina, giant retinal tear
retinal vasculature

a. causes of engorgement
b. causes of attenuation
c. causes of hemorrhage
a. hypertension, inflammation, hyperviscosity syndromes, polycythemia
b. atrophy of sensory retina, anemia, glaucoma, occlusive vascular dz, hypotension
c. trauma, inflammation, neoplasia, bleeding disorders, vascular
choroid

a. causes of thinning
b. causes of thickening
a. atrophy, hypoplasia (ex. Collie Eye Anomaly)
b. inflammation, neoplasia
What are some causes of a small optic nerve?
congenital hypoplasia: genetic lesion in dogs
coloboma: notch/pit like lesion in optic n. (lesion of CEA); may cause optic n. to look too big OR too small; same as cupping, but congenital, NOT acquired
cupping: acquired change assoc. w/ chronic glaucoma
atrophy & loss of myelin: 2° to optic nerve or retinal injury
What are some causes of a large optic nerve?
excessive myelinization: normal; may be seen in sporting breed dogs
optic neuritis (inflammation)
papilledema: swelling of optic nerve (rare)
neoplasia: rare
coloboma
Collie Eye Anomaly

a. pathophysiology
b. lesions
a. choroidal & retinal hypoplasia (generally focal); inherited in collies
b. (bilateral): choroidal hypoplasia, tortuosity of retinal vasculature, optic disc colobomas, retinal detachment (in severe cases)
spontaneous retinal dysplasia

a. pathophysiology
b. etiologies
c. lesions
a. abnormal differentiation of retina
b. familial in certain dog breeds (Lab, Cocker), Hereford cattle
-2° to retinal necrosis, generally from retinal inflammation in utero (feline panleuk, BVD, bluetongue virus)
c. linear or punctuate retinal folds – hyporeflective areas of tapetal fundus, Y shaped folds, retinal detachment (if severe)
progressive retinal atrophy

a. pathophysiology
b. signalment
a. biochemical defect in retinal metabolism, affecting rod &/or cone photoreceptors
b. dogs b'twn 2-8 yo
hypertensive chorioretinopathy

a. pathogenesis
b. signalment
c. lesions
a. sustained ↑ in systolic BP --> necrosis of vascular endothelium of retina & choroid
b. acute vision loss & dilated pupils in cats > 10 yo; occurs 2° to renal dz or may be primary; some cats also have HCM
c. retinal hemorrhage & detachment, tortuous retinal vessels, retinal degeneration
Inflammation or neoplasia of orbit results in..?
exophthalmos (protrusion of globe)
What are some causes of inflammation of the orbit?
-bacteremia
-penetrating wound
-extension from adjacent tissues: most common cause; from oral cavity (tooth root abscess), nasal cavity, sinuses
What tumors affect the orbit in

a. dogs
b. cats
c. horses
d. cattle
a. usually malignant, locally invasive, & 1° to orbit or periorbital tissues (OSA, MCT, adenocarcinoma, fibrosarcoma, malignant melanoma, lacrimal gland tumor, optic n. tumors, metastatic)
b. usually malignant, locally invasive, & 1° to orbit or periorbital tissues (LSA, SCC)
c. SCC
d. LSA (orbit is 1 site of predilection)
What is enophthalmos?
sunken globe caused by any painful stimulus
What are some common ocular sites for SCC in horse, cow, and cat?
horse: orbit, eyelid, conjunctiva, 3rd eyelid

cow: eyelid, conjunctiva, 3rd eyelid

cat: orbit, eyelid, 3rd eyelid (rare)