Conjunctiva, Cornea Flashcards
(41 cards)
What block will help you with opening the eyelid of a horse?
Auriculopalpebral nerve block
What nerve block will give you anesthesia of the upper eyelid?
Frontal nerve block (branch of trigeminal) in the supraorbital foramen
What are the three common uses of a fluorescein stain?
Diagnosis and characterization of corneal ulceration
Demonstration of nasolacrimal patency
Demonstration of corneal perforation
What are the 5 layers of the cornea?
Pre corneal tear film
Corneal epithelium
Corneal stroma
Descemete’s membrane
Endothelium
What is the most sensitive structure in the mammalian body?
Cornea
What are dermoids?
Non progressive congenital lesions consisting of epithelial and dermis like components found in an abnormal location
Where do dermoids most frequently arise from?
Limbus
What is curative for dermoids?
Complete surgical excision
What breeds are megalocornea and cornea globosa (MCOA) seen in?
Rocky mountain horses
Coat color association - chocolate coats with white mane and tail
What do horses with megalocornea and cornea globosa have an increased risk for?
Corneal ulceration and exposure keratitis
What is eosinophilic keratoconjunctivitis?
Inflammatory disease of the cornea and conjunctiva
White raised plaques on the cornea and/or conjunctiva
Most cases are within the summer months
How would you diagnose eosinophilic keratoconjunctivitis?
Eosinophils on corneal cytology
How would you treat eosinophilic keratoconjunctivitis?
Oral steroids (dexamethasone)
Oral antihistamine (cetirizine)
Topical antibiotic - only if corneal ulceration is present
When would you do a follow up for eosinophilic keratoconjunctivitis? What is the average healing time?
Initial recheck in ~2 weeks, serial follow up monthly until resolved
Takes about 2.5 months to heal
1/3 recurrence rate
What is KCS most commonly associated with in horses?
Loss of parasympathetic nerve supply to lacrimal tissue (facial nerve)
Associated with trauma, mandibular fracture, stylohyoid fracture
How would you treat KCS supportively?
Topical tear stimulant (Tacrolimus or cyclosporine)
Topical tear replacement
Topical antibiotic if corneal ulcer
What is a simple corneal ulcer?
Superficial with no signs of infection or stromal loss
How would you treat a simple corneal ulcer?
Topical antibiotic q 8 hr
Topical atropine sulfate 1% given once in clinic
Systemic NSAID q 12-24 hr
Topical antifungal q 6 hr (must be given 4x a day or they do not work)
Should be healed within 1-2 weeks
What are the common causes of corneal ulcer infection (melting)?
Bacterial - staphylococcus, streptococcus, pseudomonas
Fungal - aspergillus
What causes keratomalacia (melting ulcer)?
Secondary bacterial and/or fungal infection
Endogenous proteinases (neutrophils, corneal epithelial cells)
Previous topical corticosteroid administration
How would you treat an infected corneal ulcer?
Topical atropine sulfate 1% q 8-24 hr
Topical antifungal (voriconazole 1%) q 2-6 hr
Topical antibiotic (moxifloxacin or another fluroquinolone) q 2-6 hr
Anti-melting medication (serum, EDTA 1%, topical tetracycline, N-acetylcystine) q 2-6 hr
How long should you expect an infected ulcer take to heal?
Around 8 weeks
When would you consider surgery in an infected corneal ulcer?
> 50% stromal depth
Rapidly progressive
Melting
No vascular response
Perforated
What is a corneal stromal abscess?
Small puncture wound that seals, leaving infection and/or foreign bodies in cornea
