5: cornea - giuliano

Question 1

what are the 4 layer to the cornea? [exterior to interior]

Answer 1

epithelium
stroma
descemet’s membrane
endothelium

Question 2

which layers of the cornea are hydrophillic?

clin significanc?

Answer 2

stroma

the fluorescein stain is hydrophillic so adheres to the stroma if there is a perforation to the epithelium [corneal ulcer]

Question 3

what is a corneal ulcer?

Answer 3

exposed stroma - perforated corneal epithelium

Question 4

what are the functions of the cornea?

Answer 4

• component of fibrous tunic

- main ocular surface barrier - entry of pathogens, penetration of therapeutic agents

Question 5

t/f

any dec in clarity in the cornea is indicative of pathology

Answer 5

true

Question 6

why is the cornea clear?

Answer 6

• absence of blood vessels
• deturgescence
• regular arrangement of collagen
• absence of pigment
• relatively acellular

Question 7

what is deturgescence and how does the cornea achieve and maintain it?

Answer 7

relative dehydration of the cornea

stroma is sandwiched btwn 2 layers that keep the water out - surface layer of epithelium and endothelium

endothelium has active Na/K ATPase pumps that pump water out

Question 8

what is the order of MDB tests:

Answer 8

STT, fluorescein staining, IOP measurement

Question 9

what are the 7 deadly corneal colors?

Answer 9

red
bule
white
yellow
greasy tan
brown
black

Question 10

what do blood vessels tell you about the state of the eye / dz of the eye?

Answer 10

that the dz is due to chronic irritation

Question 11

how do vessels tell you where the dz is?

Answer 11

superficial: corneal epi dz, fine/branching (tree)
deep: stromal or intraocular dz, NON branching (hedge)

Question 12

describe conjunctival vessels?

what do they tell you about dz?

Answer 12

superficial, tortorous, branching, move w conj, blance w eip

superficial dz

Question 13

describe scleral vessels?

what do they tell you about dz?

Answer 13

deeper, straighter, less branching, immobile, blanch slowly w epi,

deep, intra ocular dz

Question 14

in general, what does hyperemia tell you?

Answer 14

vasodilation is occurring in the eye

Question 15

what 2 ocular dzz are vision robbing in a matter of 24 hours?

Answer 15

glaucoma

uveitis

Question 16

what are 2 categories of dz that superficial vessels suggest?

Answer 16

insufficient corneal protection

excessive corneal irritation

Question 17

what might cause insufficient corneal protection?

Answer 17

lagophthalmos
macropalpebral fissure
CrN 5 or 7 paralysis
ectropion
KCS

Question 18

what might cause excessive corneal irritation?

Answer 18

entropion
distichiasis
ectopic cilia
trichiasis
FB
lid tumor
blepharitis

Question 19

what types of dzz might be occurring when deep vessels are visible?

Answer 19

deep keratitis
scleritis
uveitis
glaucoma

Question 20

what does blue cornea indicate?

Answer 20

edema

Question 21

ddx?
diffuse blue color to cornea
fluorescein negative 
marked
non painful
not inflammed
normal IOP 
flare absent

Answer 21

endothelial degeneration
endothelial dystrophy

monitor for corneal bullae & 2* ulceration

Question 22

ddx?
diffuse blue color to cornea
fluorescein negative 
marked
painful
inflamed 
abnormal IOP
flare present

Answer 22

glaucoma
uveitis
anterior lens luxation

Question 23

ddx?
focal blue color to cornea
fluorescein positive
mild/focal
painful
inflammed

Answer 23

corneal ulceration

Question 24

what species MC gets infectious keratomalacia?

Answer 24

horses

Question 25

when dealing with chemicals around eyes, always make sure you use ____ and NEVER ____

Answer 25

solution and NEVER scrub

Question 26

what does whispy white/grey in the cornea indicate?

Answer 26

scar tissue - disorganization of stromal collagen

Question 27

when scar tissue is present, what will fluorescein test results be?

Answer 27

negative

Question 28

t/f scar tissue is painful for the patient

Answer 28

false

Question 29

Tx of scar tissue in the cornea?

Answer 29

none! will remodel very slowly on its own

Question 30

what does a sparkly white color in the cornea look like?

Answer 30

lipid [cholesterol] or mineral [Ca] deposits

Question 31

typical presentation of primary dystrophy of the cornea?

Answer 31

bilateral [not necessarily symmetrical] young dogs [inherited]

Question 32

what is degenaration vs dystrophy?

Answer 32

degeneration - started normal and deteriorates [often 2* to a problem] dystrophy - inherited [not necessarily congenital b/c not always present at birth]

Question 33

what are ddx of a sparkly white cornea?

Answer 33

corneal lipid degeneration corneal lipid dystrophy corneal limbal lipid infilatrates

Question 34

what is corneal lipid degeneration? often dev 2* to what condition?

Answer 34

lipid and mineral corneal stromal infiltrates that are accompanied by vascularization, scarring and pigmentation 2* to chronic corneal ulceration or non ulcerative keratitis

Question 35

what is corneal lipid dystrophy?

Answer 35

1* symmetric, bilateral, non inflammatory, inherited corneal opacity that is assoc w lipid infiltrate in the corneal stroma may affect epi [recurrent erosions], stroma or endo [chronic corneal edema] characteristic race track appearance of white tissue in cornea

Question 36

what is corneal limbal lipid infiltrates?

Answer 36

bilateral, limbal associated stromal infiltrates 2* to lipid-laden serum in the limbus may extend around entire limbus [arcus] sys hyperlipidosis - look for systemic metabolic abnormalities]

Question 37

how dies pigment get into the cornea?

Answer 37

carried there by vessels - insoluble, intracellular pigment; grows from limubs impregnated - ruptured eye [iris shows through], FB cornea sequestrum - cats, brachycephalics - necrotic cells

Question 38

pigment laid down in cornea by vessels might be due to what?

Answer 38

insufficient corneal protection [lagophthalmos, macropalpebral fissure, CrN 5 or 7 paralysis, ectropion, KCS] excessive corneal irritation [entropion, distichiasis, trichiasis, ectopic cilia, FB, lid tumor, blepharitis] immume mediated [chronic superficial keratitis (pannus)]

Question 39

what is common loc for pigment deposition in brachycephalics, such as pugs? why?

Answer 39

nasal deposition b/c medial lower eyelid entropion is common

Question 40

what do greasy / tan precipitates in the eye called and what dz do they indicate?

Answer 40

keratic precipitates (KPs) uveitis (prior or chronic) "classic" cats w FIP

Question 41

where do keratic precipitates deposit?

Answer 41

deposit as endothelial plaques

Question 42

what does yellow/green cornea indicate?

Answer 42

cellular infilatrates => stromal inflammatory cells

Question 43

what are important r/o for a green/yellow cornea?

Answer 43

bacT keratitis fungal keratitis corneal FB contusion

Question 44

what diagnostic test is ESSENTIAL for a yellow/green cornea?

Answer 44

culture and sensitivity | cytology

Question 45

what condition almost always co exists with yellow/green cornea?

Answer 45

uveitis

Question 46

what causes keratitis AND conjunctivitis?

Answer 46

feline corneal sequestrum feline eosinophilic keratitis feline herpes virus nodular granulomatous episclerokeratoconjunctivitis (NGE)

Question 47

what is pannus?

Answer 47

chronic superficial keratitis

Question 48

what is the etiology of pannus?

Answer 48

immune mediated dz of obscure cause

Question 49

what is common initial presentation of pannus?

Answer 49

begins as reddened plaque at ventrolateral cornea usually bilateral but NOT always symmetrical

Question 50

t/f pannus can progress to involve the entire cornea, eventually resulting in blindness

Answer 50

true

Question 51

what ocular structure does "atypical" pannus involve?

Answer 51

the 3rd eyelid

Question 52

risk factors to the development of pannus?

Answer 52

german shepherds and greyhounds high altitude solar radiation

Question 53

tx of pannus?

Answer 53

topical steroids topical cyclosporine b-radiation if difficult cases

Question 54

t/f pannus is a curable condition

Answer 54

false it is NOT curable - it is controllable

Question 55

what is a choristoma?

Answer 55

normal tissue in an abnormal location consider it a benign tumor

Question 56

what is a dermoid?

Answer 56

a choriostoma on the eye

Question 57

what does dermoid cause?

Answer 57

chronic irritation | dec tear production

Question 58

tx of dermoid?

Answer 58

keratectomy | +/- conjunctival graft