SAM exam 5 - eye M

How many layers in the cornea?

• four

How is the cornea epithelium attached to the stroma?

• Anchoring fibril

Turnover rate from basil to superficial cells in teh cornea epithelium

• Seven days

• so theoretically, it should take no more than seven days for a ulcer to heal

Typically an ulcer should heal between how many hours

• 48-72 hours

How much do blood vessels grow after 5 to 7 days of corneal epithelium damage?

• 0.5 mm per day

The cornea epithelium is lipophili or phobic

• Lipophilic

• this means it is a barrier to fluid and drugs passing through

• it also should not absorb any fluorescein

What causes focal edema

• When you have a ulcer

• the tear film gets absorbed by the stroma layer of the cornea, causing edema

• the stroma is like a sponge and absorbs water

What part of the cornea consists of 90% of the thickness and is hydrophlic and has no blood vessels

• Stroma

• when it is unhealthy and diseased, blood vessels appea

What causes diffuse edema?

• When there is damage to the endothelial layer of the cornea (intraocular disease)

What part of the cornea is innervated with nerves?

• Stroma - trigeminal nerve CN5)

Where are the nerves located in the stroma?

• outer third of the cornea (near epithelium)

What’s more painful a superficial ulcer or a deep ulcer?

• Superficial

You suspect a dog has an ulcer so you do a fluorine stain. Upon doing so it has a doughnut appearance stain, and there is no staining in the middle

How do you explain this?

• Animal has a Desmetocele

• the descemets membrane is exposed at this part of the cornea does not reatin fluorescein dye

• this means the eye is very close to perforate

What part of the cornea is a mono layer of hexagonal cells?

• Endothelium

• Important = this ayer is a physical barier and has an active metabolic pump that prevents stromal edema (if compromised you will get diffuse edema)

True or false

Endothelium repairs by mitosis

• False healed by cellular enlargement and migration. does not undergo mitosis

• these cells naturally decline with age

List of diagnostic test you can do to detect corneal abnormalities

• Eye examination with finoff and bio microscopy

• culture/cytology

• shermer tear test

• fluorescein dye

• biopsy

Three classifications of abnormalities you can have with the cornea

• Congenital

• ulcerative

• non-ulcerative

What congenital abnormality causes hair follicles to grow on the cornea

• Dermoid (Choristoma)

• remove by superficial keratectomy

• Note: only treat if it is bothersome to the dog, not for cosmetic purpose

List all the different types of ulcers

• Erosion

• superficial

• midstromal

• deep

• descemetocele

How long does it usually take for a superficial ulcer to heal?

• 48-72 hours

Three reasons why a ulcer does not resolve in 3 to 5 days

• Underlying cause not dealth with

• infectious

• indolent ulcer

What is a indolent ulcer?

• Failure of attachment of the epithelium to the undelrying basement membrane

• no anchoring fibrils

• Note: wont see any blood vessels

Hallmark features of indolent ulcer

• Superficial

• Non-painful to midly painful

• loose or redundant edges

• middle-aged to older dogs

• chronic in nature

• looks like a blister on eye

• predisposed breed is boxers

Indolent ulcer treatment

• remove redundant loose tissue

• perform either a grid keratotomy or diamond burr

• burr is preferred

• topical tetracycline (immuno modulator and proteinase inhibitor, antimicrobial)

• Note: recheck every 7-14 days

Adding topical tetracycline reduces indolent ulcer healing time by

• 50%

Statistically what has the best outcome for treatment options of an indolent ulcer?

• Diamond burr

• 93% healed by day 14

What happens if you do not treat a indolent ulcer

• It will eventually heal itself by granulation tissue and that area wil lnot have reoccurrence

The three syndromes in cats who have herpes

• Ophthalmia neonatorum less than four weeks old

• Adolescent cat ocular and respiratory component

• adult cat localized to ocular only

Which type of cat get symblepharon

• Post neonatal herpes infection

Pathognomic ulcers with herpes

• Dendritic/punctate ulcers

Cat presents with blepharospasm and conjunctivities

List three differentials in a cat

• Chlamydia

• Calicivirus

• Herpes

On staining when do you see inclusion bodies with chlamydia?

• day 7-21

• treatment doxycycline

70% of cats are carriers of herpes.

What does this mean for the cat?

• Recurrent conjunctivitis/keratitis in periods of stress or immunosuppression (FELV/FIV/immunosuppressant drugs)

Whats the gold standard for diagnosing herpes?

• Response to treatment

• Dont do PC not a good test

Topical Q12 hour treatment for FHV-1

• Cidofovir

Systemic treatment for FHV

• Famciclovir

• 90mg/k bid

• poor efficacy in shelter cats use Cidofovir

• Do not underdose or taper drugs

Wh do you add tear mucus supplement with a cat that has active FHV?

• Mucus bines, tears to the cornea and with FHV goblet cells are targeted

What nutraceutical helps keep herpes in remission

• Lysine

What secondary inflammatory response can occur due to a mid stromal corneal ulcer

• Reflex response in which they develop anterior uveitis

• treat with atropine to dilate the pupils (no more than four times a day)

Treatment for a midstromal corneal ulcer

• Broad spectrum antibiotic

• Triple antibioti ointment = neomycin - bacitarcin - polymyxin

• Also: Levofloxacin or Gatifloxacin

How do you treat a deep/desmetocele ulcer

• surgery and medical therapy

What is the surgey of choice to treat a deep corneal ulcer?

• Conjunctive flap or corneal - conjunctival transposition

• Note: do not treat with a third eyelid flap

What causes a melting corneal ulcer

• Enzymatic breakdown of the cornea

Where do these enzymes come from?

• Neutrophils

• Keratocytes

• bacteria

What are the two common bacteria that would cause this enzymatic breakdown of the cornea?

• Pseudomonas and beta Streptococcus

How to treat melting ulcers?

• Treat aggressively with antibiotics every one - two hours (Fluoroquinolones)

• Anti-collagenous (serum or tetracycline)

• possible surgery (debride will decrease neutrophils)

Dermoid, squamous cell carcinoma, sequester, and melting ulcer

What is the first thing you do surgically to repair?

• Superficial keratectomy

After you do a superficial keratectomy what surgial procedue do you do if you need to reinforce the area

• Conjunctival graft (this vascular, rises the area to promote healing)

How to you treat a cornea perforation?

• Cornea - conjunctival graft (combination of both)

All corneal lesions, including non-ulcerative diseases decrease the transparency of the corna

List four basic changes that result in a change in corneal transparency

• edema

• pigmentation

• scar

• infiltrates (cellular or non-cellular)

List the etiologies for diffuse corneal edema

• Anterior uveitis

• glaucoma

• endothelial dystrophy

• anteior lens luxation

What has high pressure and low pressure when comparing glaucoma and anterior uveitis

• Glaucoma = high pressure

• interior uveitis = low pressure

• so if a dog comes into the clinic and you do a stain, however no ulcer and you notice diffuse edema and you check the pressure this can help you differentiate

What is the differential if you have diffuse corneal edema, normal pressure and bilateral that is not painful

• Endothelial dystrophy

• (premature loss of corneal endothelial cells that die off faster than the dog)

• Begins laterally and progresses to entire cornea

What two breeds are predisposed to endothelial dystrophy

• Chihuahu and Boston terrier

Three treatment options for corneal endothelial dystrophy

• Hyperosmotic

• fresh transplant

• conjunctival graft (most common)

Three things that cause corneal pigmentation

• Chronic superficial irritation (needs to melanin production and keratinization)

• sequestrum

• Melanoma (Milano sites located at the corneal - sclera junction)

What infection in cats is associated with corneal sequstration

• Herpes

How can a vet cause corneal sequestration?

• Applied topical steroids to an ulcer

• Grid keratotomy

True or false

It is contraindicated to do a gid keratotomy in cats

• True

Treatment for corneal sequestrum

• Superficial keratectomy

• ± supportive therapy, such as conjunctive graft or corneal transplant

• topical antibiotics, atropine, and artifical tears following surgery

Eye melanomas in cats and dogs is benign or malignant

• Benign

• Treatment with surgical excision if growing

How do you diagnose loss of transparency due to corneal scar

• Presence of vascularization and lack of pain

Non-neoplastic ifnlammatory mass most commonly seen in cocker spaniels and collies

Will see lymphocytes, plasma cells and histiocytes

• Nodular granulomatous episclerokeratitis

• can affect one or both eyes and it grows and advance

Therapy for NGE (nodular granulomatous episclerokeratitis

• Topical steroids or topical immunosuppressive (cyclosporine or tacrolimus)

What triggers chronic superficial keratitis (pannus)

• UV (more commonly seen in higher elevations)

• affects German shepherds and greyhounds

Descibe chronic superficial keratitis

• Affects both eyes and non-painful

• Corneal vascularization and pigmentation that advances across the entire cornea (immune mediated disease - T cells)

What cellular infilitrate condition affects cats

• Eosinophilic keratitis (diagnose with cytology and confirmed with mast cell or eosinophil)

• Note: all these conditions start at lateral cornea

When treating eosinophilic keratitis what do you need to consider because this being a cat?

• Cats have herpes and corticosteroids are immunosuppressive (can lead to sequetrum)

Treatment of choice for eosinophilic keratitis

• Topical ovaban

Non-cellular cordial infilitrates consists of ___ material such as ___ as it ____.

• Crystalline

• cholesterol or mineral

• can be divided into primary or secondary

primary non-cellular infilitrates is also called corneal dystrophy

describe three characteritics of cornea dystrophy

• Non-painful

• non-vascularized

• often bilateral

Is treatment required for corneal dystrophy

• No

Secondary non-cellular infilitrates is also known as corneal degeneration

Corneal degeneration is often secondary to

• Previous corneal inflammation (leftover inflammatory debris)

• Bunch of metabolic endocrine diseases = hypothyroid, hypercalcemia, diabetes, hypercholesterolemia of cushings

What part of the eye is not recognized immunologically by the body

• Lens

• its covered by a capsule, but if that capsule ruptures, then you have a rejection of tissue

• Phacoanaphylaxis

What is the most severe chemical lesion in an eye?

• Alkaline

• followed by acid and then soap

• soap will heal by itself (atropine, and antibiotics)

• acid add tetracycline and serum because it will become a melting ulcer

What gland lives in the eyelids?

• Meibomian gland (produces outer layer of the tear film lipid portion that helps tears from evaporating)

Normal cornea and eyelid size

• Cornea = 16mm

• eyelids = 23-25mm

Underlined cause of almost all entropion and ectropion

• Macroblepharon (big eyelids)

Sugical treatment to correct macroblepharon

• Permanent lateral canthoplasty

What kind of stitch pattern do you use for permanent lateral canthoplasty to realign the eyelid margin

• Cruciate pattern

What is a sign that a dog is suffering from entropion

• Wet hair on the lateral side of the eye

• tears usually flow medially however the hair is wicking the tear film and now the lateral side is wet

What surgical approach do you use to permanently correct ectroprian

• Modified Hotz celsus

• 6-0 suture

What is unique about feline entropion

• Unilateral

• still do bilateral surgery

What causes medial canthal entropian irritation, in brachycephalic type dogs

• Haired caruncle

• medial canthoplasty is a harder surgery

What is distichia

• Abnormal hairs arising from the meibomian gland and exiting out of the eyelid margin (only interfere as a clinician if it bothers the dog)

What is ectopic cilia

• abnormal hairs arising from the meibomian gland but exiting out of the palpebral conjunctiva

True or false

treatment of choice for distichia is plucking the hairs out

• False

• treatment of choice = cryosurgery, electroepilation, CO2 laser (all these kill the follicle)

• side effect = depigmentation (short term)

• give carprofen to manage swelling post-surgically

Distichia you do not need to treat if does not bother their dog.

Does the same role apply for ectopic cilica

• No, usually always have to treat

• usually present with always a head nod when they blink due to rubbing against cornea

Cats can suffer from a condition called upper eyelid agenesis

this is usually bilateral and occurs laterally

if it does not bother cornea no surgical intervention however if bothersome what surgical approach

• LIp to lid

Who gets more eyelid neoplasia cats or dogs

• Dogs (most are benign 90%)

• cats usually get malignant and are more aggressive

If you are going to remove the tumor how much can you remove?

• 1/3 if positioned 12 and six

If you need to incorporate cutaneous tissue that has artery and vein what type of surgical approach

• Axial pattern flap

Old and young horse what type of tumors would they get of the eyelid

• Older = SCC 7-9 (rarely metastasize)

• younger = sarcoids (3-6)

• Fo eyelids intralesional chemo is an option (carboplatin, and cisplatin)

True or false

You have a eyelid laceration. under no circumstances should a pedicle of eyelid be amputated

• True

• avoid excessive tissue debridement and prior disinfect with povidone iodine

Conjunctiva has what type of cells that make mucin

• Goblet cells

• Mucin binds, tears to tear film

Goblet cells make mucin which is responsible for

• mucus binds tear film to the corneal epithelium

Nictating membrane (thirds eyelid) producers, how much of the tier in dogs

• 30-50%

clinical signs of conjunctivitis

• Conjunctival hyperemia

• chemosis (swelling)

• lymphoid follicles

• ocular discharge

Number one cause of conjunctivitis in dogs

• KCS

What form of conjunctivitis is most seen in younger dogs that is seasonal

• Follicular conjunctivitis

• reved up immune system due to antigens

• treatment = topical steroids (dogs grow out of it)