Week 3 Diseases of the Conjunctiva and Nictitating Membrane Flashcards
What structures of the the eye does the conjunctiva cover?
Nictitans- covers palpebral & bulbar surface of NM
Palpebral surface- lines eyelids
Bulbar- lines globe
Fornix- divest of conjunctiva @ transition from lid to globe
What is the normal flora of the conjunctiva and why is it important
Gram + strep and staph
Occasionally gram- & fungus (e. Coli, PS spp, acinobacter)
Choose abx wisely! Normal flora can be opportunistic
What are the clinical features of conjunctivitis
Hyperemia, chemosis (swelling and billowing of conjunctiva), follicles, ocular discharge
how can you differentiate between conjunctival and episcleral hyperemia both visibly and with pharmacological testing?
Conjunctival- surface disease, can move vessels, epinephrine will cause blanching
Episcleral- intraocular disease, stationary vessels
What are the most common causes of canine conjunctivitis and how are they diagnosed and treated
KCS sic can ‘dry eye’ - schrimer tear test
Follicular & allergic
Canine bacterial infection rare!
What is follicular conjunctivitis, what area does it affect and how is it treated
Immune-mediated, environmental irritants
Bulbar surface of nictitating membrane, inferior fornix
Dex t-QID then taper
Is a culture/susceptibility an important diagnostic procedure to work up canine conjunctivitis?
No, bacterial conjunctivitis is rare in dogs
What is the most common cause of feline conjunctivitis, how would you diagnose and treat it, what treatment is contraindicated
FHV-1
Clinical signs, stain to look for dendritic ulcers, look for corneal staining and inactive vessels
Give topical oxytetracycline, anti-viral not needed unless ulcer
Corticosteroids contraindicated!! Promote latent virus
How is equine eosinophilic keratoconjunctivitis treated medically?
Topical anti-histamine, maybe ivermectin and NSAID
Topical abx/atropine if ulcer
What are the two most common causes of bovine conjunctivitis
IBR - peripheral corneal edema and ulcer, do herpes IFA, Tx topical abx
IBK moraxella bovis- conjunctival hyperemia & chemosis, central corneal abscess and edema, dx culture and clinical signs
What are the two most common causes of bovine conjunctivitis
IBR - peripheral corneal edema and ulcer, dx herpes IFA,Tx topical abx
IBK moraxella bovis- conjunctival hyperemia & chemosis, central corneal abscess and edema, dx culture and clinical signs, tx oxytet
What are the two most common infectious causes of conjunctivitis is sheep and goat
Mycoplasma sp, chlamydia, moraxella ovis
Name 3 conjunctival parasites
Thelazia, onchocerciasis, habronema
List 4 conjunctival tumors in small animals
SCC, papillomas, hemangioma, melanoma
What is the most common conjunctival tumor in horses and cattle?
Squamous cell carcinoma
What is the purpose of the “T” cartilage of the nictitans
Gives structural support, retains concave curvature that conforms to globe
What two techniques can be used to examine the nictitans
Forced retro pulse on of the globe & protrusion of the membrane
What congenital abnormality occurs with the T-cartilage in large breed dogs
Scrolled cartilage
What is it important to replace rather than remove a prolapsed gland of the third eyelid (cherry eye)? What sx treatment is recommended
Tears are essential, pocket imbrication technique
What is the only indication for surgical removal of the nictitans/gland of the nictitans
Squamous cell carcinoma
Name 3 common tumors of the nictitans
Lymphosarcoma, adenocarcinoma of gland of the nictitans, conjunctival neoplasia that involves the nictitans (SCC, hemangioma)
How is squamous cell carcinoma of the third eyelid in a horse best treated
Excision of the nictitans and adjunctive cryotherapy
What is plasmoma do how would you treat it? What breeds are commonly affected?
Irregular reddening, thickening and depigmentation of margin of nictitans
Usually bilateral
Collie, GSD, sighthounds
Immune mediated, lymphoplasmasitic inflam
Topical corticosteroids, topical 2% cyclosporine, doggles
What are the causes of nictitans elevation?
Enophthalmos, exophthalmos, “haws syndrome” (cats)
