Week 3 Diseases of the Conjunctiva and Nictitating Membrane

Question 1

What structures of the the eye does the conjunctiva cover?

Answer 1

Nictitans- covers palpebral & bulbar surface of NM
Palpebral surface- lines eyelids
Bulbar- lines globe
Fornix- divest of conjunctiva @ transition from lid to globe

Question 2

What is the normal flora of the conjunctiva and why is it important

Answer 2

Gram + strep and staph

Occasionally gram- & fungus (e. Coli, PS spp, acinobacter)

Choose abx wisely! Normal flora can be opportunistic

Question 3

What are the clinical features of conjunctivitis

Answer 3

Hyperemia, chemosis (swelling and billowing of conjunctiva), follicles, ocular discharge

Question 4

how can you differentiate between conjunctival and episcleral hyperemia both visibly and with pharmacological testing?

Answer 4

Conjunctival- surface disease, can move vessels, epinephrine will cause blanching

Episcleral- intraocular disease, stationary vessels

Question 5

What are the most common causes of canine conjunctivitis and how are they diagnosed and treated

Answer 5

KCS sic can ‘dry eye’ - schrimer tear test

Follicular & allergic

Canine bacterial infection rare!

Question 6

What is follicular conjunctivitis, what area does it affect and how is it treated

Answer 6

Immune-mediated, environmental irritants

Bulbar surface of nictitating membrane, inferior fornix

Dex t-QID then taper

Question 7

Is a culture/susceptibility an important diagnostic procedure to work up canine conjunctivitis?

Answer 7

No, bacterial conjunctivitis is rare in dogs

Question 8

What is the most common cause of feline conjunctivitis, how would you diagnose and treat it, what treatment is contraindicated

Answer 8

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

Question 9

How is equine eosinophilic keratoconjunctivitis treated medically?

Answer 9

Topical anti-histamine, maybe ivermectin and NSAID

Topical abx/atropine if ulcer

Question 10

What are the two most common causes of bovine conjunctivitis

Answer 10

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

Question 10

What are the two most common causes of bovine conjunctivitis

Answer 10

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

Question 11

What are the two most common infectious causes of conjunctivitis is sheep and goat

Answer 11

Mycoplasma sp, chlamydia, moraxella ovis

Question 12

Name 3 conjunctival parasites

Answer 12

Thelazia, onchocerciasis, habronema

Question 13

List 4 conjunctival tumors in small animals

Answer 13

SCC, papillomas, hemangioma, melanoma

Question 14

What is the most common conjunctival tumor in horses and cattle?

Answer 14

Squamous cell carcinoma

Question 15

What is the purpose of the “T” cartilage of the nictitans

Answer 15

Gives structural support, retains concave curvature that conforms to globe

Question 16

What two techniques can be used to examine the nictitans

Answer 16

Forced retro pulse on of the globe & protrusion of the membrane

Question 17

What congenital abnormality occurs with the T-cartilage in large breed dogs

Answer 17

Scrolled cartilage

Question 18

What is it important to replace rather than remove a prolapsed gland of the third eyelid (cherry eye)? What sx treatment is recommended

Answer 18

Tears are essential, pocket imbrication technique

Question 19

What is the only indication for surgical removal of the nictitans/gland of the nictitans

Answer 19

Squamous cell carcinoma

Question 20

Name 3 common tumors of the nictitans

Answer 20

Lymphosarcoma, adenocarcinoma of gland of the nictitans, conjunctival neoplasia that involves the nictitans (SCC, hemangioma)

Question 21

How is squamous cell carcinoma of the third eyelid in a horse best treated

Answer 21

Excision of the nictitans and adjunctive cryotherapy

Question 22

What is plasmoma do how would you treat it? What breeds are commonly affected?

Answer 22

Irregular reddening, thickening and depigmentation of margin of nictitans

Usually bilateral

Collie, GSD, sighthounds

Immune mediated, lymphoplasmasitic inflam

Topical corticosteroids, topical 2% cyclosporine, doggles

Question 23

What are the causes of nictitans elevation?

Answer 23

Enophthalmos, exophthalmos, “haws syndrome” (cats)