Test 2: lecture 27+28 cornea

Question 1

Answer 1

descemet’s membrane
above the endothelial cell layer of cornea

Question 2

layers of the cornea

Answer 2

epithelial layer 6-15 layers
stroma- collagen avascular
descemet’s membrane
single endothelial cell layer

Question 3

how does cornea get nutrition

Answer 3

front from: aqueous layer of tears

edothelial cell layer from: anterior chamber- aqueous humor

Question 4

function of the cornea

Answer 4

refraction of light

main barrier to penetration by mirco-organisms

Question 5

Answer 5

conjunctiva hyperemia

episcleral congestion

conjunctiva clear membrane over sclera, then episcleral membrane, then sclera

Question 6

why is cornea clear

Answer 6

avascular
regularly arranged collagen
relatively dehydrated: Na/K pumps in the internal endothelial layer, that pumps H20 out

Question 7

Answer 7

corneal edema

Question 8

what causes this

Answer 8

corneal edema

corneal epithelium or endothelium becomes damaged and there is a build up of fluid inside the cornea

bluish- cobblestoned

endothelial disease: diffuse
epithelial- focal/corneal ulcer

Question 9

diffuse blue eyes means

Answer 9

endothelial disease leading to edema in the cornea

distemper

Question 10

damage to what layer of the cornea will lead to focal/corneal ulcers

Answer 10

epithelial (outer layer)

Question 11

3 causes of endothelial disease of the cornea

Answer 11

breed related endothelial dystrophy
* spontaneous, progressive
* Boston

age-related endothelial degeneration
* common

secondary/intraocular disease
* uveitis
* glaucoma

disruption of Na/K pump- makes blue eyes- edema of cornea

Question 12

bullous keratopathy

Answer 12

progressive cornea edema that leads to bulla/blister formation and corneal ulcer

can treat with Na/Cl solution

Question 13

how to treat bullous kertopathy

Answer 13

Na/Cl soultion

thermokeratoplasy- burn cornea to form scar that prevents fluid from coming into cornea

progressive edema- blisters that lead to corneal ulcers

Question 14

acute bullous keratopathy in cats

Answer 14

can happen suddenly/over night

emergency- can lead to corneal rupture

systemic cyclosporine appears to be a risk factor- may be from descemet’s membrane damage

treat by forcing eye closed for a few weeks

Question 15

corneal ulcers is caused by loss of —

Answer 15

epithelium +/- stroma

Question 16

Answer 16

descemetocele

damage of cornea down to descemet’s membrane, then pressure of eye pushes membrane up forming bubble- needs surgery ASAP

Question 17

superficial ulcers heal by

Answer 17

rapid epithelialization
5-7 days

Question 18

what causes melting?

Answer 18

collagenases

deep ulcers require vascularization and collagen deposition

collagenases are used during wound healing to reform collagen layers- bacteria can cause over activaity of collagenases that then “melt/eat” the eye

Question 19

can you use pred on corneal ulcer?

Answer 19

no!

it will cause increased collagenase activity → melting of cornea

Question 20

what are the “little trees”

Answer 20

blood vessels form to try to heal corneal ulcer

take 3-5 days to form, grow 1mm/day

never go away but blood leaves once healing is done

Question 21

initial treatment of superficial corneal ulcer

Answer 21

remove underlying cause: eyelash, thorn ect

give ecollar to prevent rubbing

antibiotics- 3-4 x a day

there are no pain meds for eye!
* can use atropine to stop spasms but will dilate pupil for long periods

Can’t use steroids- will cause worse problems

Question 22

1st step to treat infected ulcer

Answer 22

take cytology
culture

use Q 2 hr fluoroquinolones

Question 23

what can help with corneal melting?

Answer 23

anti-collagenase

serum: has antiprotease/anticollagenases in it

give every 2-4 hours

Question 24

prognosis of complicated corneal ulcer

Answer 24

can take 3 weeks to heal

initial 48 hours checks, if ulcer is improving/not getting any deeper can wait and let eye heal

if not improving, may need surgery

Question 25

when to consider surgery on corneal ulcer

Answer 25

greater then 80% deep descemetocele corneal perforation not getting better with medial treatment

Question 26

surgery to fix deep ulcers

Answer 26

conjunctival graft tectonic support- promotes healing and fibroblasts

Question 27

indolent corneal ulcer are

Answer 27

superficial uninfected corneal ulcer that does not heal in appropriate time epithelilal cells are damaged for some reason | boxers- SCCED, feline herpes

Question 28

how to treat indolent corneal ulcer

Answer 28

debride/ scratch off epithelial layer and let eye try to make new layer better promotes epithelialization, vascularization can use qtip of diamond butt debridement

Question 29

why do contacts help with healing

Answer 29

protect new epithelial layer from being rubbed away when blinking

Question 30

pannus

Answer 30

**chronic superficial keratitis** cause by UV damage usually starts **ventralateraly** and moves progressively inwars common in german shepherd

Question 31

--- starts ventrolaterally and is a progressive chronic superficial keratitis caused by ---

Answer 31

pannus UV light/ immune mediated? common in german shepherd

Question 32

how to treat pannus

Answer 32

steroids, tacrolimus often managed not cured- can lead to blindness

Question 33

--- is similar to pannus in cats

Answer 33

**eosinophilic keratitis** proliferation with eosinophil and mast cells can be caused by feline herpes

Question 34

what kind of cells in pannus vs eosinophilic keratitis

Answer 34

**pannus:** dogs: plasma cells **eosinophilic keratitis:** cats: eosinophils and mast cells

Question 35

how to treat eosinophilic keratitis

Answer 35

steroids and antivirals steroids can risk making underlying feline herpes virus worse managed, rarely cured cat/horse eye- pink/white raised plaques in ventral/lateral eye

Question 36

Answer 36

corneal pigmentation- melanin deposition non- specific response to inflammation dogs pugs and pekingese

Question 37

how to treat corneal pigmentation

Answer 37

melanin deposition is in response to inflammation try to remove cause of inflammation increase lubrication can suture eyelid mostly closed in pugs to allow eyelids to blink- increase protection of cornea

Question 38

what can cause corneal sequestrum

Answer 38

cats breed specific: himalyains feline herpes corneal ulcer entropion corneal debridement ## Footnote change in color from corneal necrosis. NOT the same as corneal pigmentation in dogs which in mealnin deposition

Question 39

Answer 39

corneal sequestrum- change in color from corneal necrosis. NOT the same as corneal pigmentation in dogs which in mealnin deposition can be caused in certain breeds or from herpes, chronic corneal ulcer, entropion, or corneal debridement ## Footnote treat: keratectomy +/- graft

Question 40

how to treat corneal sequestrum

Answer 40

happens in cats cut out necrosis- **keratectomy +/- graft**

Question 41

white crystalline is caused by ---

Answer 41

corneal mineralization lipid or calcium from systemic disease (high fat) or topical corticosteroids ## Footnote treat: underlying cause, stop steroids

Question 42

Answer 42

corneal dystrophy bilateral slow progression heritable- husky 4-6 years old usually lipid, not painful, no treatment

Question 43

how to treat corneal dystrophy

Answer 43

no treatment not painful bilateral slow progression, heritable (husky)- round white **lipid** accumultion in the eye

Question 44

--- is deposition of calicum into cornea after chronic corneal disease

Answer 44

corneal degeneration common in old dogs +/- vascularization can be painful, recurrent corneal ulcers ## Footnote treat: lubricant, keratectomy

Question 45

how to treat corneal degeneration

Answer 45

topical lubricant keratectomy calcium deposition from chronic corneal disease → painful

Question 46

Answer 46

episcleritis nodular +/- pain immune mediated: cocker spaniels ## Footnote treat: steroid and doxy

Question 47

episcleritis occurs in

Answer 47

cocker spaniels immune mediated? nodular +/- painful ## Footnote treat: steroid and doxy

Question 48

how to treat episcleritis

Answer 48

topical immunosuppression oral doxycycline; corticocsteroids ## Footnote nodular +/- painful, immune mediated- cocker spaniels

Question 49

five-year old DSH 24-hour history of a painful, wet left eye STT: 15 OU fluroscein positive OS PLR present OU anisocoria OS< OD (left pupil smaller then right) list two possible causes for the fluorescein uptake in the left eye what is your initial treatment plan? what is the prognosis?

Answer 49

corneal ulcer or herpes treat with lubricant and antibiotic, e-collar anti viral wait- depending on how deep, check in 48 hours if stable let heal for 7-10 days good if superifical, poor if deep and doesnt heal well herpes life long disease