Pathology of the eye Flashcards
What are the parts of the outer tunic of the eye?
sclera and cornea
What are the parts of the vascular tunic of the eye?
choroid, iris, and ciliary body
What are the parts of the neural tunic?
the retina
What is the area between the cornea and the sclera called?
the limbus
When there is retinal separation, where does it occur?
in between the retina and the retinal pigment epithelium
What type of cells does the retinal pigment epithelium interact with?
photoreceptors
Describe the epithelium of the eye.
it is stratified squamous epithelium, highly organized, 5-6 layers, and does not keratinize
Describe the stroma of the eye.
specialized type of fibrous connective tissue, much less fluid than other parts of the eye, composed of collagen
What is Descemet’s membrane?
a thick basement membrane produced by corneal endothelium
Where is Descemet’s membrane located?
in between the stroma and the corneal endothelium
What is the purpose of the corneal endothelium?
it prevents the aqueous humor from leaking into the stroma
What is the function of the pectinate ligament?
it allows aqueous humor to seep through
What is the pectinate ligament connected to?
Descemet’s membrane
Where is the tapetum lucidum located?
in the dorsal part of the retina
Which layers of the retina is the tapetum lucidum located in between?
the choroid and the retinal pigment epithelium
What is the difference between corneal erosion and corneal ulcers?
Corneal erosion is loss of epithelium down to the basement membrane and corneal ulcers go through the basement membrane
What usually is the cause of corneal erosion?
trauma
What are the causes ulcers?
trauma and certain bacteria and viruses
What is a melting ulcer?
when bacteria complicate the ulcer by producing metalloproteinases that dissolve the cornea
What is a descemetocele?
an ulcer that goes down into Descemet’s membrane
How do you know if you have a desmetocele?
the ulcer becomes clear in the middle
What is a perforated ulcer?
when the iris adheres to the ulcer
Ulcers are usually associated with ________.
inflammation
Where will exudate in ulcers come from?
the conjunctiva
How is erosion repaired?
epithelium looses up then the epithelium proliferates, slides onto the basement membrane and fills in
What can cause erosion to be recurrent?
if injury damages basement membrane then there are issues with attachment
What are the steps of ulcer repair?
epithelial proliferation, stromal neovascularization, and stromal fibrosis
Where does stromal neovascularization begin?
in the periphery at the limbus
What does ulcer repair create?
scar tissue
What is corneal edema?
fluid accumulation within the stroma due to the loss of epithelial or endothelial barrier
What causes corneal edema?
disruption of stromal fiber organization
What does corneal edema look like grossly?
a cloudy eye
What is the cause of chronic epithelial hyperplasia?
chronic persistent injury such as dry eye
What is another term for chronic epithelial hyperplasia?
epidermalization
What lesion does chronic epithelial hyperplasia cause?
rete ridge formation and keratinization
What is corneal neovascularization?
blood vessel ingrowth from the limbus into the peripheral stroma
What is stroma fibrosis?
the replacement of regular corneal fibrous stroma with scar tissue
What may stromal fibrosis resemble?
the dermis due to cutaneous metaplasia
What is inflammation of the cornea called?
keratitis
What types of exudate are associated with keratitis?
serous, fibrinous, purulent, and granulomatous
Where does exudate come from in keratitis?
conjunctiva, tears, and anterior uvea
Where does exudate accumulate in in keratitis?
epithelium, stroma, or adheres to the endothelium
What are keratitic precipitates?
when exudate from keratitis sticks on the endothelial side
What is feline corneal sequestration?
necrosis to the corneal stroma as the result of an ulcer; occurs at the base of the ulcer
How does feline corneal sequestration appear grossly?
as discrete brown focal discoloration
What is goniodysgenesis?
the incomplete or dysplastic development of the iridocorneal angle, pectinate ligament, and ciliary cleft
What can goniodysgenesis contribute to?
primary glaucoma
What is choroidal hypoplasia?
a thin choroid
What is choroidal hypoplasia associated with?
color-dilution mutant coat patterns
What is anterior uveitis?
inflammation to the iris and ciliary body
What is panuveitis?
inflammation to the iris, ciliary body, and choroid
What types of exudate is associated with uveal inflammation?
all types except catarrhal
In the case of uveal inflammatino, where does exudate that originates in the iris leak into?
the anterior chamber causing a hazy look in the eye
In the case of uveal inflammation, where does exudate leak to that originates in the choroid?
into the subretinal space
What causes uvual inflammation?
infectious agents, autoimmune, and phacoclastic uveitis
What is phacoclastic uveitis?
the lens ruptures and fibers enter into the eye
What is preiridial fibrovascular membrane?
PIFM! The proliferation of fibrovascular tissue on the anterior surface of the iris
Is PIFM acute or chronic?
chronic
What may PIFM result in?
anterior synechia, posterior synechia, closure of the iridocorneal angle, entropion uveae, and ectropion uveae
What is anterior synechia?
adhesion of the iris to the cornea
What is posterior synechia?
adhesion of the iris to the lens capsule
What can closure of the iridocorneal angle cause?
secondary glaucoma
What is entropion uveae?
inward contraction of pupillary margin
What is ectropion uveae?
outward contraction of the pupillary margin
What causes intra-ocular hemorrhage?
trauma, inflammation, hypertensive vasculopathy, and neoplasms
What may intra-ocular hemorrhage result in?
a detached retina
What are some common uveal neoplasms?
melanoma, ciliary body epithelial tumors, and lymphosarcoma
Where are uvual melanomas located?
in the anterior uvea and they do not usually spread past the eye
What parts of the uvea do lymphosarcomas usually include?
anterior uvea and choroid
What does retinal dysplasia cause?
wrinkles and folds rosettes
What causes retinal dysplasia?
genetic, viral infection during development
What is an example of a viral infection that causes retinal dysplasia?
bovine viral diarrhea
If there is inflammation in the retina is it usually exclusively in the retina?
no
What exudate types (infiltrates) are associated with retinal inflammation?
neutrophils, lymphocytes, macrophages, and PC (whatever that is)
What is degeneration/atrophy of the retina?
neuron loss from various layers depending on cause
What does degeneration/atrophy of the retina cause?
photoreceptor loss, collapse and gliosis
What causes retinal degeneration/atrophy?
ischemia, glaucoma, nutritional deficienccy, drugs, detachment, genetic, inflammation
When the retina detaches, what does it separate from?
the RPE
What results from retinal detachment?
hypertrophy of the RPE and loss of photoreceptors (long term result)
What causes retinal detachment?
hemorrhage, transudate from hypertensive vasculopathy, and exudate
What is microphakia?
a small underdeveloped lens
What causes Microphakia?
usually a congenital defect that is associated with other defects
Describe a cataract.
lens opacity due to disruption of fiber organization
What lens fiber changes occur in cataracts?
swelling, fragmentation, liquefaction, Morgagnian globules, mineralization
What causes cataracts?
congenital, aging, diabetes mellitus, and others
Where are cataracts located?
subscapular, anterior, and posterior
What is a hypermature cataract?
lens fibers liquefy and leak out; the lens collapses
What is nuclear sclerosis?
aging due to compression of nuclear lens fibers (there is constant re-epithelialization and the older fibers in the middle compress)
What is inflammation to the lens called?
phacitis
What is phacitis secondary to?
penetrating injury
What type of infiltrate is associated with phacitis?
pmns
What happens if the lens capsule ruptures due to phacitis?
it may cause phacoclastic uveitis
How does a luxated lens occur?
the zonules, the fibers that hold the lens in place, become ruptured
What happens to the lens when the lens is luxated?
it moves around; usually ventrally or anteriorly\
What happens if the luxated lens is lodged in the pupil?
a pupillary block
What is epithelial fibrous metaplasia secondary to?
rupture of the lens capsule
In cats, what occurs, potentially many years after, due to trauma to the lens?
trauma-induced-ocular sarcoma of cats
What is entropion?
the rolling in of the eyelid
What is ectropion?
the rolling out of the eyelid
What is inflammation of the eyelid called?
blepharitis
When the glands of the eyelid and the eyelid are involved, what is the inflammation called?
Meibomian adenitis
What is chalazion?
granulomatous inflammation of Meibomian glands and the eyelid
What neoplasms are associated with the eyelid?
melanoma, squamous cell carcinoma, meibomian gland tumors
What is inflammation of the conjunctiva and/or the third eyelid called?
conjunctivitis
What is pannus of the eye?
proliferation of fibrovascular tissue that grows onto the cornea; interface LP inflammation of the cornea
What neoplasms are associated with the conjunctiva?
squamous cell carcinoma
What is inflammation of the sclera called?
episcleritis
Describe episcleritis.
it is inflammation on the surface of the sclera and may extend into the 3rd eyelid
What are the two forms of episcleritis?
granulomatous form and necrotizing form
What is microphthalmia?
when the eye is small - there is a small underdeveloped globe
What is endophthalmitis?
the inflammation of all interior segments and chambers
What is panophthalmitis?
inflammation of all components of the eye
What is buphthalmos?
an enlarged globe
What is the cause of buphthalmos?
increased intraocular pressure secondary to glaucoma
What is phthisis bulbi?
atrophy of the globe - the eye was normal at one time but is not normal anymore
