Ocular

Question 1

Define Aqueous flare

Answer 1

Aqueous humor turbidity caused by inflammatory cells and/or protein in the anterior chamber. Pathognomonic for breakdown of the blood-eye barrier.

Question 2

Define PIFM

Answer 2

Preiridal fibrovascular membranes- proliferation of vessels on anterior face of the iris. Can overgrow and cause peripheral anterior synechiae.

Question 3

Define synechiae (anterior/posterior)

Answer 3

Anterior synechiae- adhesion of the iris to the cornea.
Posterior synechiae- adhesion of the iris to the lens, causes iris bombe.
Caused by increase in adhesiveness due to fibrin and/or PIFM.

Question 4

Define iris bombe

Answer 4

Pupillary block causing distended iris into anterior chamber.

Question 5

Define keratitis

Answer 5

Inflammation of the cornea.

Question 6

Define uvea

Answer 6

Vascular tunic of the eye including iris, ciliary body and choroid.

Question 7

Describe uveitis

Answer 7

Inflammation of the vascular system of the eye (the uvea) causing migration of neutrophils and macrophages out of vessels and into eye, proliferation of lymphocytes and plasma cells that form perivascular cuffs/lymphoid follicles, and release of inflammatory mediators in the aqueous humor.

Question 8

Define cyclitis

Answer 8

Inflammation of the ciliary body

Question 9

Define cataract

Answer 9

Any opacification of the lens. Can be caused by chronic uveitis.

Question 10

Characterize glaucoma

Answer 10

Optic neuropathy characterized by retinal ganglion death, optic nerve cupping, optic nerve axonal loss, and vision loss. Caused by increase in intraocular pressure.

Question 11

Define Goniodysgenesis

Answer 11

Abnormal development of the iridocorneal/filtration angle where a thick bank of uveal tissue blocks normal aqueous flow and predisposes animals to glaucoma.

Question 12

Define Peripheral anterior synechiae

Answer 12

Adhesion of the iris to the iridocorneal angle/overgrowth of PIFM covering angle, results in secondary glaucoma.

Question 13

Define Persistent pupillary membranes

Answer 13

Remnant iridal tissue connecting iris to lens or cornea, may cause focal corneal opacity or focal cataract, usually clinically insignificant.

Question 14

Define Hypopyon

Answer 14

Settled neutrophils and macrophages that migrate into the anterior chamber, contributes to aqueous flare.

Question 15

Define Hyphema

Answer 15

Blood in the anterior chamber due to spontaneous hemorrhage of the fragile new vessels of preiridal fibrovascular membranes on the anterior iris.

Question 16

What is the role of the epithelium and the endothelium in maintaining optical clarity in the cornea?

Answer 16

Epithelium is hydrophobic barrier, endothelium pumps water out to dehydrate

Question 17

What are the three characteristics that make the cornea transparent?

Answer 17

Dehydration
Avascularity
Regular array of collagen lamellae and keratocytes

Question 18

3. What are the most common causes of corneal opacification? Explain 3 of them.

Answer 18

Foreign body, scarring (white, indistinct borders), neoplasm or inflammatory infiltrate (yellow/creamy, indistinct borders), deposits (white, crystalline, sharp borders), pigment (brown/black, sharp borders), vascularization, edema (blue haze, indistinct borders)

Question 19

4. Name 3 causes of corneal edema and explain their pathogenesis.

Answer 19

Epithelial ulcers- loss of hydrophobic barrier, movement of water into stroma
Stromal vascularization- leaky blood vessels
Endothelial defects- diffuse deep corneal edema due to loss of pump function because of: endothelialitis (CAV-1, Bovine herpesvirus), degeneration, trauma, glaucoma, uveitis

Question 20

5. Explain the pathogenesis and lesions associated with keratoconjunctivitis sicca in dogs, in acute and chronic cases. Name two common breeds affected.

Answer 20

Dog breeds commonly affected: King Charles Cavalier Spaniels, Cocker Spaniels, Lhasa Apsos, Shih Tzus, Bulldogs, Pugs, Boston Terriers, Pekingese
Defect in aqueous component of tear film from lacrimal gland/3rd eyelid gland
Causes: autoimmune, infectious, removal of 3rd eyelid, neurological disease
Acute: corneal ulcerations, mucopurulent ocular discharge
Chronic: corneal epithelium undergoes epidermalization- thickening, pigmentation, neovascularization, inflammation, ridge formation

Question 21

6. What is the best place to look histologically to find fungus in mycotic keratitis of horses?

Answer 21

Descemet’s membrane and deep corneal stroma

Question 22

7. What is the causative agent of bovine pink eye? Which are the physical factors related to the spread of disease in bovine pink eye?

Answer 22

Moraxella bovis
Corneal irritation by UV light, flies, or long grasses

Question 23

8. Name 3 morphologic/histopathologic hallmarks of equine recurrent uveitis?

Answer 23

Lymphocytic inflammation of the uvea
Eosinophilic membrane coating ciliary processes
Intracytoplasmic inclusions in non-pigmented ciliary body

Question 24

9. What is the definitive cause of Equine recurrent uveitis?

Answer 24

Likely incited by Leptospira infection followed by immune-mediated recrudescence
Multi-factorial and not fully understood

Question 25

10. What are the most common causative agents of systemic mycosis that also affect the eye? Which most commonly affects dogs and cats? What do they all cause?

Answer 25

-Blastomycosis (most common in dogs) -Cryptococcosis (most common in cats) -Coccidiosis (SW US only) -Histoplasmosis (most common in dogs and cats) All cause pyogranulomatous chorioretinitis

Question 26

11. What is the definitive cause of lymphoplasmacytic uveitis in cats? What is this disease characterized by?

Answer 26

Idiopathic Bilateral anterior uveitis Iridal nodules = lymphoid follicles

Question 27

12. Name the consequences of uveitis that might be responsible for the development of glaucoma?

Answer 27

Lymphoid follicle proliferation can obliterate the iridocorneal angle, block aqueous flow, and lead to secondary glaucoma

Question 28

13. Retinal detachment occurs when there is a separation between which layers?

Answer 28

Neurosensory retina and the retinal pigment epithelium

Question 29

14. Name several pathologic processes which might be responsible for retinal detachment.

Answer 29

Serous detachment – breakdown of blood-eye barrier and exudation from choroid vessels into subretinal space Traction – vitreal traction bands pull on retina to detach Rhegmatogenous - vitreous dissects through a retinal tear into the subretinal space

Question 30

15. What are the most common ocular lesions observed in animals with systemic hypertension?

Answer 30

Hypertensive vasculopathy/chorioretinopathy, serous retinal detachment

Question 31

16. What are the most common causes of secondary glaucoma?

Answer 31

-Uveitis: peripheral anterior synechiae, posterior synechiae  iris bombe, inflammatory cells/fibrin clogs trabecular meshwork blocking aqueous outflow -Trauma/Hyphema: blood cells clog trabecular meshwork -Lens luxation: trauma or spontaneous  lens stuck in anterior chamber  blocks outflow of aqueous -Neoplasia: obliteration or obstruction of iridocorneal angle with neoplastic cells

Question 32

17. How are the following abnormalities related to the potential development of glaucoma? A. Peripheral anterior synechiae

Answer 32

PIFM grows over iridocorneal angle to block access to trabeular meshwork

Question 33

17. How are the following abnormalities related to the potential development of glaucoma? B. Hypopyon/hyphema

Answer 33

Neutrophils, macrophages, and/or RBCs block trabecular meshwork

Question 34

17. How are the following abnormalities related to the potential development of glaucoma? C. Goniodysgenesis

Answer 34

Congenital malformation of iridocorneal angle results in incomplete rarefaction of the pectinate ligaments between the iris root and limbus which cover the entry to the iridocorneal angle and block aqueous outflow

Question 35

17. How are the following abnormalities related to the potential development of glaucoma? D. Neoplasia

Answer 35

Neoplastic cells can directly obliterate the iridocorneal angle or sloughed neoplastic cells and/or RBCs can clog the angle and block outflow

Question 36

18. Characterize the morphologic hallmarks of goniodysgenesis.

Answer 36

Presence of a thick band of uveal tissue extending from the iris base to the terminus of Descemet’s membrane of the cornea and covering the iridocorneal angle

Question 37

19. Describe the optic nerve and retinal lesions associated with glaucoma

Answer 37

Retinal atrophy, cupping of optic nerve head, end stage: buphthalmia (eye enlargement), lens luxation, phthisis bulbi

Question 38

20. What are the most common primary ocular tumors in the dog and cat?

Answer 38

Dog: Melanocytoma (80%), Malignant melanoma (20%), anterior uvea Cat: Diffuse Iris Melanoma (FDIM)

Question 39

21. Distinguish between feline diffuse iris melanoma and anterior uveal melanocytic tumors in dogs. Characterize the likely metastatic behavior of each. What is possible secondary outcome of both tumor types?

Answer 39

FDIM: grossly dark freckles in iris that coalesce over time. Metastasis occasional. Melanocytic dog tumors: Single pigmented mass in anterior eye that grows and can take over the globe. Metastasis rare. Both can cause secondary glaucoma.

Question 40

22. What is the cell thought to be responsible for feline post-traumatic sarcoma?

Answer 40

Lens epithelial cells released during lens capsule rupture

Question 41

23. Describe the common biologic behavior of conjunctival and corneal squamous cell carcinoma in the horse and ox. Is metastasis likely?

Answer 41

Horse: Arise from third eyelid margin Cattle: Arise from conjunctiva at limbus, less often eyelids or cornea Both associated with viral infection and UV light and can metastasize late.

Question 42

24. Name several tumors that commonly metastasize to the eye.

Answer 42

Lymphoma Histiocytic sarcoma Melanoma Hemangiosarcoma Mammary adenocarcinoma