Veterinary Medicine - Ophthalmology Flashcards
Name the 3 layers of the tear film and where they’re produced
Oily layer - Meibomian glands
Aqueous layer - Lacrimal glands: 2\3 produced in the upper eyelid, 1\3 in the 3rd Eyelid
Mucin layer - Goblet cells in the conjunctiva
Name common causes for third eyelid to be elevated and whether we expect unilateral or bilateral elevation
Retrobulbar disease (Abscess, Neoplasia) - unilateral
Dehydration Cachexia (Bilateral)
Pain (Unilateral if local pathology, can be also bilateral)
Define the limbus
Where 3 tissues meet: Sclera, Conjunctiva and Cornea
What are the 2 functions of the ciliary bodies?
Hold the lens
Produce the aqueous humor
Which of the retinal blood vessels disappear first in retinal degeneration
Retinal arterioles
What is the function of the tapetum
Improves night vision
Hyperreflective is indicative of..?
Retinal thinning (e.g. due to retinal atrophy, retinal scarring)
Hyporeflective retina is indicative of..?
Retinal edema (Inflammation)
Blue-colored tapetum can be seen in…?
Young puppies (2 months of age)
Retinal pigmented epithelium - dark color might suggest..? Mildly transparent (Can partially see choroidal blood vessels)..? Completely see-through (Choroidal blood vessels completely visible)..?
Dark - Dark densely colored fur.
Mildly transparent - Brighter fur color (e.g. light brown).
Transparent - Albino
What are 2 differences in the cat’s optic disc and retinal blood vessels
Optic disc is not myelinated (at least portion visible in fundoscopy)
All blood vessels start at the edge of the optic disc and not cross it (as opposed to the retinal veins which do cross in dogs)
Entropion - Clinical signs
Blepharospasm
Enophathalmus
Epiphora
Eyelid discoloration
Conjunctivitis
Corneal ulcers (Which can also lead to 2nd Uveitis)
Entropion - Why does it cause epiphora in small brachycephalic breeds?
Due to the eyelid caving in and blocking the puncta which drains the tears into the lacrimal duct. Can also be due to pain as with all breeds
Entropion - What are the 2 components of every entropion? how to differentiate between them?
Anatomic
Spastic (due to pain)
Local anesthetics
What breeds are predisposed to combined entropion-ectropion (“Diamond-shape”)?
Giant breeds
Define distichiasis
Cilia originating from the Meibomian gland
Define trichiasis
Normal eyelid cilia that turn 180 degrees towards the eye
Define ectopic cilia
Ectopic cilia that originates from the inner eyelid (upper eyelid) at 90 degrees towards the eye
Ectopic Cilia - Where is the only location it can be found at
Upper eyelid (On the inside)
Define “Stye” and how do you treat it?
Meibomitis and subsequent obstruction of the Meibomian gland.
Burst it manually -> Warm compress -> local antibiotics
Post-operative care for eyelid operations
Elizabethan collar
Systemic antibiotics
Systemic analgesia
*Systemic - because we don’t want owners to come into contact with the area that was operated on
3 DDs for “Red eye”
Conjunctivitis
Uveitis
Glaucoma
Causes for conjunctivitis in dogs
Mechanical irritation (Eyelid abnormalities such as Entropion, Distichiasis, Ectopic cilia etc., Foreign body)
Infectious diseases (e.g. Distemper, Leishmaniasis)
KCS
Allergies
Insect bites
Conjunctivitis in dogs - Treatment
Treat underlying cause (!)
Local antibiotics
Local anti-inflammatory treatment (NSAIDs\Steroids)
Causes for conjunctivitis in cats
Herpes
Chlamydia
Causes for 3rd eyelid elevation (Bilateral)
Dehydration
Cachexia
Haws syndrome (cats)
What are the 3 elements of Horner’s syndrome
Lowered upper eyelid
3rd Eyelid elevation
Miotic pupil
Define “Cherry eye”
Prolapse of the tear gland on the medial side of the 3rd eyelid
What is the most common cause for Keratoconjunctivitis sicca (KCS) in dogs
Primary - Autoimmune disease
Keratoconjunctivitis sicca (KCS) - Causes
Autoimmune disease (Most common)
Neurogenic KCS (Along with Xeromycteria Facial paralysis) - due to otitis interna
Infectious diseases (e.g. Leishmaniasis, Distemper, FHV)
Endocrine (e.g. Hypothyroidism, DM)
Drugs (e.g. TMS (irreversible), Atropine (reversible), Anesthesia)
Ocular causes: Blepharoconjunctivitis, Removal of tear glands (Inappropriate treatment of “Cherry eye”)
Keratoconjunctivitis sicca (KCS) - Infectious causes (dogs and cats)
Leishmaniasis
Canine distemper virus
Feline herpes virus
Keratoconjunctivitis sicca (KCS) - Diagnosis
Schirmer tear test
Schirmer tear test - What are the reference intervals for normal, abnormal
<5 mm\min - KCS
5 - 15 mm\min - Suspicious
> 15 mm\min - Normal
Keratoconjunctivitis sicca (KCS) - Treatment
Clean secretions
Artificial tears
Local antibiotics if indicated. Immunosuppression: 1st Line: Cyclosporine A (Excellent) 2nd Line: Tacrolimus
*In neurogenic cases - Pilocarpine (Parasympathomimetic agent)
Parotid duct transposition (Surgical)
Tear-film breakup time test - Used to diagnose what? What is the deficiency?
Qualitative KCS
Mucin layer (Produced by the goblet cells in the bulbar conjunctiva)
2 General Causes for Epiphora
Excess production (e.g. due to irritation, Pain, foreign body, Eyelid abnormalities)
Drainage block
Epiphora due to drainage block - Common causes
Congenital (e.g. Imperforate puncta, Micropuncta)
Dacryocystitis
Entropion
Tear stain syndrome - Common breeds (Dogs and cats)
Brachycephalic dogs and cats, Miniature dogs
Tear stain syndrome - Common cause in affected breeds (Dogs and cats)
Brachycephalic and miniature dogs - Entropion causes corneal irritation and medial entropion also causes blockage of the nasolacrimal duct
Brachycephalic cats - Congenital abnormal kinking of nasolacrimal duct
Epiphora - Diagnosis
Full ophthalmic exam to look for causes for excessive tear production
Nasolacrimal duct blockage:
-Florecin flushing (“Jones test”).
-Cannulation through the upper puncta (diagnostic and possibly also curative)
Corneal ulcers - What are the 2 types of vascularizations that occur in order to facilitate repair? What are their origins?
Superficial (Conjunctiva)
Deep (Ciliary bodies)
What other pathology can always accompany corneal ulcers and should require consideration and prophylactic treatment?
Anterior uveitis
Corneal ulcers - Epithelial defect - Usually doesn’t stain with florecin (Which only stains exposed stroma). How can you stain it and what is a common cause for epithelial defects in certain animals?
Rose Bengal
FHV in cats
Corneal ulcers - Desmatocoel - How would it appear with florecin staining
Only the periphery of the ulcer is stained while the center remains black (no stroma left)
Corneal ulcers - Treatment
Treat underlying cause
Local Systemic antibiotics (Depending on severity)
Inhibit proteolysis in melting ulcers (Local: Tetracycline\Serum\Plasma)
Treat 2nd uveitis: NSAIDs, Atropine.
Elizabethan collar
Contact lenses
For deep and severe ulcers: Surgical intervention (e.g. Conjunctival flap)
Why is Atropine indicated in uveitis (2nd to corneal ulcers or otherwise) - 2 reasons
Analgesia (Iridial spasms are painful)
Mydriasis (to prevent glaucoma 2nd to uveitis)
A Corneal ulcer has not started healing after 2 days of treatment. What are your next diagnostic steps
C&S (Pseudomonas? Chlamydia?)
Cytology (Bacteria? Fungus?)
Check for Boxer ulcers
2 Possible sequelas to Persistent Pupillary Membrane
Focal cataract if PPM attaches to the lens
Corneal opacity and edema if PPM attaches to the cornea
3 Common causes for diffuse corneal edema (“Blue Eye”)
Glaucoma
Anterior uveitis
Anterior lens luxation
Lipid keratopathy - How does it Look Like? What are the general causes & common DDs
Arcus Lipidosis - Crescent moon shape on the periphery of the cornea
Hypertriglyceridemia\Hypercholesterolemia: Cushing’s disease, Hypothyroidism, DM, Pancreatitis
Corneal degeneration - Causes
Ocular Inflammation (e.g. Uveitis, Keratitis)
Systemic hypercalcemia
Hypophosphatemia
Hypervitaminosis D
Uremia
Pannus - Predisposed breeds
German shepherd
Belgian Malinois
Pannus - Treatment
Reduce UV exposure
Topical steroids
Cyclosporine\Tacrolimus
Superficial Keratectomy
Anterior uveitis - causes in dogs (Bilateral)
Infectious diseases (e.g. Leishmaniasis, Ehrlichiosis, Leptospirosis, Toxoplasmosis, Canine adenovirus, Distemper, Blastomycosis, Histoplasmosis).
Idiopathic - Most common cause (~50% of cases)
Anterior Uveitis - Common causes (Unilateral)
2nd to Corneal ulcers
Trauma
Neoplasia
2nd to Cataract (Lens-induced uveitis)
Anterior Uveitis - Clinical signs
Blepharospasm
3rd Eyelid elevation (Pain)
Miosis
Conjunctival hyperemia
Corneal edema (“Blue Eye”)
Congested iris
Aqueous flare
Hypopyon, Hyphema, Fibrin, Keratic\Phakic precipitates
Posterior synechia
Anterior Uveitis - Possible complications
Iris bombe
Glaucoma
Cataract (In cats)
Anterior Uveitis - Treatment
Treat underlying cause (!!)
NSAIDs\Steroids (Depending if 2nd to corneal ulcer) - Local\Systemic (Depending on severity)
Atropine (Mydriasis, Analgesia)
Tissue Plasminogen Activator (TPA) for preventing\dissolving fibrin adhesions
Hyphema - Causes
Trauma
Uveitis
Coagulopathies (Thrombocytopenia, Thrombocytopathy, Decrease in coagulation factors)
Hypertension
Hyperviscosity Syndrome
Neoplasia