Exam1 Notes

Question 1

Requirements for Vision

Answer 1

Clear cornea
o normal eyelid function
o adequate tear film
o no pigment, vessels or cellular infiltrates
o relative dehydration

Clear aqueous
o no inflammation
o intact blood-eye barrier (uvea)

Clear lens

Functional central pathways from optic nerve to cortex

Question 2

Vision in Domestic Animals

Answer 2

o superior night vision due to more rods & tapetum
o decreased visual acuity due to less cones

Question 3

Menace response

Answer 3

o vision (CNII)
o trigeminal (CNV)
o facial (CNVII)
o central pathway

Question 4

Third Eyelid

Answer 4

o Located in the medial canthus
o covered with conjunctiva
o contains lacrimal tissue, lymphoid tissue and cartilage,
o protect the cornea
o provide a portion of the tear film

Question 5

Which Species Do Not have a Tapetum?

Answer 5

pig, camelids, some birds

Question 6

Layers of the Eye

Answer 6

Outer fibrous tunic
o cornea
o sclera

Middle vascular (uvea)
o iris
o ciliary body
o choroid

inner nervous layer
o retina

Question 7

Dermoid; basics, treatment

Answer 7

o Skin and hair that develop in an abnormal place
o commonly affect the cornea, but in some cases only the eyelid and/conjunctiva

Treatment
o surgical removal with careful reconstruction of the affected eyelid margin

Question 8

Eyelid Agenesis; Basics, Treatment

Answer 8

o congenital defect
o usually affects upper lateral eyelids in the cat
o occasionally seen in the lower eyelids of dogs
o leads to pain & corneal trauma

Treatment
o Corrective, reconstructive surgery

Question 9

Ophthalmia Neonatorum; Basics, Treatment

Answer 9

o result of an infection occurring prior to the natural lid opening at 10-14 days
o causes swelling behind the eyelids and purulent exudate.

Treatment
o eyelids need to be gently opened & irrigated
o topical antibiotic ophthalmic ointment
o cornea needs to be kept moist.

Question 10

Entropion; Basics, Treatment

Answer 10

o rolling inward of the eyelid causing hair to rub on the cornea
o hereditary in many dog breeds
o may have a later age of onset.
o premature foals, lambs, Shar Pei puppies and alpacas.

Treatment
o Eyelid tacking temporarily
o Vertical mattress sutures can be left in place for several weeks
o may not require further treatment

Question 11

Acquired Entropion; Basics, Treatment

Answer 11

o may be the result of trauma or chronic pain
o seen after chronic conjunctivitis or keratitis in cats

Treatment
o May resolve with topical anesthetic (spastic entropion)
o surgical correction w/ Hotz-Celsus procedure.

Question 12

Ectropion; Basics, Clinical Signs, Treatment

Answer 12

o outward rolling of the eyelid
o considered “normal” in some breeds
o may be associated with an entropion of the same lid

Clinical Signs
o Exposure of the conjunctiva
o irritation and chronic ocular discharge

Treatment
o surgery
o very challenging!!

Question 13

Distichiasis; Basics, Treatment

Answer 13

o hair (cilia) emerging from the meibomian gland openings
o Soft hairs directed away from the patient may not be a clinical problem
o hairs that are more rigid and directed toward the cornea are painful, cause corneal damage, and delay healing of corneal ulcers

Treatment
o removed by electroepilation
o cryosurgery if multiple distichia are present. (Referral procedure)

Question 14

Ectopic Cilia; Basics, Clinical Signs, Treatment

Answer 14

o hairs that grow under the eyelid
o from the base of the meibomian gland through the conjunctiva
o directed toward the cornea

Clinical Signs
o very painful
o Ulcers located just below the cilia (usually 12 o’clock) quickly progress.

Treatment
o Surgical removal under an operating microscope (referral procedure)
o Temporary protection of the cornea by a contact lens until referral is possible

Question 15

Trichiasis; Basics, Treatment

Answer 15

o abnormal direction of growth of hair from a normal site.

Clinical Signs
o At medial canthus they act as a wick and pull tears onto the face
o chronic irritation to the cornea -> corneal pigmentation -> reduced vision

Treatment
o medial canthoplasty (referral)
o entropion surgery for minor medial entropion causing trichiasis.

Question 16

Eyelid Laceration; Basics, Treatment

Answer 16

o common eyelid injury in horses

Treatment
o should be surgically repaired as soon as possible
o precise eyelid alignment
o Minimal (or no) debridement is important to preserve as much eyelid margin as possible
o healing is generally good.
o Closure should start at lid margin using V-I plasty

Question 17

Eyelid Tumors; Basics, Treatment

Answer 17

o very common in the dog (generally benign)
o less common in cat but malignant
o Severe inflammatory disorders in the cat are difficult to distinguish from neoplasia

Clinical Signs
o wart like growth on eyelid
o corneal irritation
o mucoid discharge

Treatment
o up to 1/3 of the lid margin can be removed in dogs
o 1/4th in cats,
o V to I plasty.
o CO2 laser ablation
o cryotherapy

Question 18

Eyelid Sx Guidelines

Answer 18

o Prep skin with dilute (1:10) betadine solution
o prep conjunctival sac with 1:50 dilution
o 5-0 or 6-0 silk for skin
o 6-0 vicryl subq.
o figure of 8 pattern at the lid margin

Question 19

Blepharitis; Basics

Answer 19

o inflammation of the eyelids
o inciting factor must be identified
o Cytology to identify and treat bacteria and malassezia
o Biopsy may be necessary for diagnosis.

Question 20

Cherry Eye (Prolapsed Gland of the 3rd Eyelid); Basics, Treatment

Answer 20

o breed associated disorder but can occur in any breed
o usually bilateral
o contraindicated to remove the gland unless there is a tumor present

Treatment
o ‘Morgan pocket technique’ widely used to replace the gland but has significant rate of failure w/ inexperienced surgeons
o Securing the gland to the inferior rectus (referral procedure)

Question 21

Follicular Conjunctivitis; Basics, Treatment

Answer 21

o dogs under 24 months old.
o immune or allergic condition that the patient will outgrow

Clinical Signs
o Hyperplastic lymphoid follicles are seen behind the 3rd eyelid
o conjunctival hyperemia
o ocular discharge

Treatment
o topical antibiotic/steroid (BNP-HC or NP Dex) continued at lowest possible interval until the patient “outgrows” the problem.
o can try hypoallergenic diet
o can try topical cyclosporine
o can try mast cell blockers

Question 22

Scrolled Cartilage; Basics, Treatment

Answer 22

o defect of the T-cartilage
o causes the 3rd eyelid to bend
o causes irritation and discharge

Treatment
o referral sx to remove the distorted portions of the cartilage

Question 23

Neoplasia of the 3rd Eyelid; Basics, Diagnosis, Treatment

Answer 23

o more commonly seen in horses
o most common of the horse, cat and cow is SCC.
o often malignant in dogs.

Diagnosis
o deep incisional or an excisional biopsy is needed
o Chest radiographs and advanced imaging of the area may be necessary

Treatment
o need to be removed early or become inoperable

Question 24

Tears; Function, Flow

Answer 24

Function
o nutrition, moisture, and protection for the cornea
o refraction and corneal healing

Flow
o puncta (superior and inferior) ->
o canaliculi ->
o lacrimal sac ->
o naso-lacrimal duct ->
o nose or mouth

Question 25

Tear Components

Answer 25

Mucin
o secreted by goblet cells
o found in the conjunctiva
o innermost layer of tear film
o smooths the corneal epithelial cells and binds hydrophilic aqueous tears to the lipophilic corneal epithelium.

Aqueous
o secreted by the orbital lacrimal gland & the gland of the nictitating membrane
o keeps the cornea moist and nourished.
o middle layer and the bulk of the tear film

Lipid
o secreted by the meibomian glands
o holds aqueous tears against cornea and keeps them from spilling over eyelids
o prevent evaporation of tears

Question 26

Imperforate Puncta; Basics, Clinical Signs, Treatment

Answer 26

o congenital defect
o puncta covered by conjunctival epithelium that fails to regress during development and prevents tears from entering the canaliculus

Clinical Signs
o young dog with epiphora with a non-painful eye

Treatment
o surgical correction (referral procedure)

Question 27

Nasal-lacrimal Obstruction; Basics, Clinical Signs

Answer 27

o often due to a foreign body, tumor or dental disease (rabbits).

Clinical Signs
o Epiphora
o copious mucopurulent discharge
o No obvious discomfort
o does not resolve with medical therapy

Question 28

Dacryocystitis; Basics, Treatment

Answer 28

o inflammation of the nasal-lacrimal system
o usually associated with a foreign body or dental disease.

Treatment
o treat underlying cause
o topical or systemic antibiotics and anti-inflammatories

Question 29

Meibomian gland adenitis; Basics, Treatment

Answer 29

o inflammation of the meibomian glands
o often secondary to blepharitis
o associated with staph infection

Treatment
o warm compresses to the eyelids
o oral doxycycline

Question 30

Normal STT Values for Dog, Cat, Horse

Answer 30

o Dog = 15 – 25 mm/min.
o Cat = highly variable
o Horse = highly variable 10 to >30mm/min.

Question 31

Keratoconjunctivitis sicca - KCS –“DRY EYE”; Basics, Clinical Signs, Treatment

Answer 31

o most common cause of conjunctivitis in dogs
o result of conjunctivitis in cats

Clinical Signs
o Conjunctival hyperemia
o Pain (blepharospasm)
o NO epiphora
o Mucoid discharge – often copious and very tenacious
o Dry lusterless cornea, may be pitted, pigmented, ulcerated and vascularized
o STT< 15mm/min

Treatment
o treat underlying cause
o Remove mucoid exudate & perform cytology to treat secondary bacterial infection.
o Immunosuppressive drugs (cyclosporine or tacrolimus)
o Natural tear replacement
o Pilocarpine if neurogenic KCS is suspected
o Topical antibiotic based on cytology
o PDT - Parotic Duct Transposition (salvage referral procedure)

Question 32

Basics of the Conjunctiva

Answer 32

o provides protection, lubrication and “cushion” for eye movement.
o caruncle is the conjunctival ‘nodule’ located in medial canthus.
o contains goblet cells that secrete the mucin layer of tear film
o normal flora includes staph, strep, a few gram neg. bacteria and mycotic organisms

Question 33

Conjunctivitis; Basics, Clinical Signs, Causes

Answer 33

o very common in the DOG, CAT and HORSE
o clinical sign, not a clinical diagnosis.

Clinical Signs
o Diffuse hyperemia,
o chemosis (edema)
o ocular discharge (serous, mucoid or mucopurulent)
o blepharospasm.

Causes
o KCS & allergies in dogs
o Herpes of Chlamydia in cats (don’t use steroids)
o ulcers or intraocular disorders in horses

Question 34

Conjunctivitis; Diagnostic Steps

Answer 34

In order
o STT
o Topical anesthetic after completing a STT.
o Cytology
o C & S if the infection has been refractory to initial treatment
o Fluorescein stain
o Oral exam
o N-L flush
o Intraocular exam
o Rule out orbital disease, neoplasia and cellulitis
o Rule out systemic disease
o Response to topical antibiotic or anti-inflammatory (NSAID safer than steroid)

Question 35

Allergic Conjunctivitis

Answer 35

o may be seen with generalized allergic signs (pruritis, foot licking, otitis) or seen as conjunctivitis alone
o may respond to topical antibiotics +/- steroids, and topical mast cell blockers (ketotifen).
o neomycin/polymyxin/bacitracin (BNP) w/ or w/o hydrocortisone (BNP-HC) used for dogs
o Corneal ulcer must be ruled out before starting steroids

Question 36

Corticosteroids Used in the Eye

Answer 36

Hydrocortisone
o mild allergies and irritants
o does not penetrate cornea

Dexamethasone
o follicular conjunctivitis
o strong steroid
o penetrates cornea

Prednisolone acetate
o penetrates cornea (prednisolone phosphate does not)
o used for anterior uveitis.

Question 37

Corneal Ulcers; Clinical Signs, Diagnosis

Answer 37

Clinical Signs
o usually painful
o conjunctival hyperemia
o tearing,
o chemosis and/or ocular discharge

Diagnosis
o fluorescein stain
o slit beam to determine depth
o magnification and a cobalt filter in a darkened room

Question 38

Equine Conjunctivitis; Causes, Treatment

Answer 38

Causes
o wind and dust
o corneal ulceration
o Anterior uveitis
o systemic dz
o Parasites,
o SCC,
o solar
o trauma
o eyelid abnormalities

Treatment
o Topical BNP is a good first choice
o Any case that does not resolve in a day or two should be reassessed

Question 39

Cornea; Function & Anatomy

Answer 39

o refractive surface (bends light)
o corneal epithelium is 3-5 cell layers thick
o lipophilic
o intact epithelium does not take up fluorescein (hydrophilic) stain.
o superficial cornea (stroma) is highly innervated by the trigeminal nerve -> superficial ulcers more painful than deep ulcers.

endothelium
o single layer of cells lining the interior of the cornea
o active Na-K-ATPase water pump to maintain corneal deturgescence (dehydration)
o does not regenerate

Question 40

Stroma; Function & Anatomy

Answer 40

o thickest layer of the cornea
o composed of parallel bundles of collagen fibers and GAG’s
o gives the cornea its shape and integrity
o hydrophilic and will stain with fluorescein if exposed (ulcer)

Question 41

Descemet’s membrane; Function & Anatom

Answer 41

o basement membrane for the corneal endothelium
o innermost layer of the cornea
o does not take up fluorescein stain when exposed by a deep ulcer
o may bulge forward into the stromal defect
o last layer before the cornea is perforated.

Question 42

Corneal Edema; Basics, Causes of Focal Vs Generalized

Answer 42

o result of disruption of the epithelium or damage to the endothelium.
o blue-white mottled or cobblestone appearance
o loss of corneal transparency.

Focal
o epithelial loss (ulcer)
o allows tear film to overhydrate the stroma

Generalized
o endothelial pump failure
o increased IOP – ‘disables’ pump
o uveitis-toxic to pump
o endothelial dystrophy
o endothelial degeneration
o anterior lens luxation
o immune complex (adenovirus Vx)

Question 43

Endothelial Dystrophy of the Cornea; Basics, Treatment

Answer 43

o commonly seen in middle aged to older dogs
o Usually starting at the temporal limbus
o water bullae form near the epithelial surface and rupture -> painful

Treatment
o 5% NaCl ointment to dehydrate the epithelium (3-4x per day & dz will progress)
o superficial keratectomy and place a permanent graft over the corneal stroma (dz does not progress)

Question 44

Lipid Dystrophy of the Cornea; Basics, Treatment

Answer 44

o subepithelial deposition of lipids due to genetics, corneal trauma, hyperlipidemia or other metabolic disorders
o non-painful, progressive
o worsened with topical steroid use
o Over time the cornea may degenerate with superficial calcium deposition -> painful ulcerations

Treatment
o low- fat diet to slow lipid deposition

Question 45

Superficial Corneal Ulcer in Dogs; Healing & Treatment

Answer 45

o should be healed w/in 5 days
o if over 7 days, change diagnosis!

Treatment
o eliminate cause
o Topical BNP - good 1st antibiotic
o Atropine to prevent ciliary spasm (contraindicated in KCS & glaucoma)
o E-collar
o pain management but not NSAIDs - delay healing

Question 46

Superficial Corneal Ulcer in Cats; Healing & Treatment

Answer 46

o same as dogs
o accept NO BNP
o use erythromycin or terramycin as antibiotic

Question 47

Indolent Ulcers; Basics

Answer 47

o Any superficial ulcer that has not healed/improved in over 5 days w/ no underlying cause
o superficial, painful, and do not involve the stroma
o no infection or melting.
o failure of the attachment apparatus of the basal epithelial cells to the stroma
o corneal vascularization can be robust or not

Question 48

Indolent Ulcers; Treatment in dogs

Answer 48

o debride the corneal epithelium with a CTA removing all loose epithelium
o contact lens placement (for 1 week)
o oral tramadol or butorphanol or topical morphine drops (not a steroid)
o atropine ointment (contraindicated in KCS or glaucoma)
o topical neomycin/polymyxin/gramicidin or tobramycin every 8hrs until no stain uptake.
o Topical NaCl 5% ointment if corneal edema.
o E-collar **
o Doxycycline may shorten corneal epithelial healing time
o DO NOT repeat debridement
o refer if still not healing

Question 49

Deep Stromal Ulcer; Basics

Answer 49

o deep or progressive ulcers
o usually the result of trauma, inappropriate use of steroids, infected ulcers, or KCS.
o Stromal ulcers take longer to heal and will leave a scar.
o corneal surface will have a concave defect.
o If ulcer is 50% or more of corneal thickness, consider surgery to promote faster healing

Question 50

Descemetocele; Basics, Treatment

Answer 50

o deep ulcer breached entire stromal thickness and exposed Descemet’s membrane
o may appear as a deep defect that only takes up fluorescein stain around the rim
o may bulge due to intraocular pressure.
o if perforated, aqueous will leak resulting in a wet face and a very painful cry.

Treatment
o surgery (graft) is the best option.
o aggressive medical therapy may allow epithelium to cover defect
o Any pressure on the eye or mechanical disturbing of Descemet’s membrane will cause the eye to rupture

Question 51

Melting Ulcers; Basics

Answer 51

o caused by steroids, neutrophils, or bacteria/fungi that produce/contain proteinase
o perforate quickly (hours).
o more common in horses than in dogs or cats.
o culture and cytology samples from the center of ulcer to look for infection

Question 52

Melting Ulcers; Treatment

Answer 52

Treat AT LEAST every hr alternating between serum & EDTA

Anti-proteinase therapy hourly
o EDTA
o Tetracycline-topical or oral
o Serum
o Acetylcystein

Antibiotics:
o Neomycin / polymyxin / gramicidin or bacitracin
o Enrofloxacin
o Gentamycin
o Chloramphenicol
o Tobramycin
o Terramycin
o Ofloxacin or Ciprofloxacin

If does not respond to therapy or worsens surgical keratectomy & conjunctival graft

Question 53

Stromal Abscess; Basics, treatment

Answer 53

o sterile or septic
o bacterial or fungal
o may be associated with a corneal ulcer
o very painfu
o can be distinguished from edema and lipid by creamy, solid appearance.

Treatment
o surgical excision (keratectomy) and a graft

Question 54

German Shepherd Pannus; Basics

Answer 54

o Chronic Superficial immune mediated Keratitis
o not painful
o often have gray ocular discharge.
o usually non-ulcerative
o many breeds are predisposed
o leads to vision loss due to corneal pigmentation if not controlled
o requires life-long management
o triggered and exacerbated by UV light
o often starts at the inferior lateral limbus but superior limbus in Greyhounds

Question 55

Pannus; Treatment

Answer 55

o Cyclosporine (Optimmune)
o NPDex: (neomycin, polymyxin, dexamethasone)
o Avoid UV light
o Doxycycline as immune modulator in initial treatment 2 wks
o Hypoallergenic diet
o Terramycin topically - may have immune modulating benefit

Question 56

Pigmentary Keratitis; Basics, Treatment

Answer 56

o Pigmentation of the cornea secondary to corneal exposure, irritation, low tear flow, poor tear film, aberrant hairs or growths
o NOT an inflammatory disease
o Steroids should NOT BE USED
o intervene early & preserve vision by preventing pigment

Treatment
o medial or lateral canthoplasty
o removal of cilia and lid abnormality correction
o cyclosporine or tacrolimus

Question 57

Corneal Neoplasia; Basics, Treatment

Answer 57

o uncommon in dogs and cats,
o SCC associated with long term use of CsA or tacrolimus.
o SCC is common in cattle and horses lacking pigment of the eyelids and bulbar conjunctiva

Treatment
o Surgical excision via superficial keratectomy
o Need clean margins

Question 58

Limbal Melanomas; Basics, Treatment

Answer 58

o In some cases there is no progression of the tumor but if progression, should treat

Treatment
o full thickness excision w/ a tectonic graft
o partial thickness excision with diode laser

Question 59

Persistent Pupillary Membranes (PPMs); Basics

Answer 59

o embryologic remnants that fail to regress by 6wks of age.
o may be incidental iris to iris
o iris to cornea or iris to lens cause focal cataracts on the lens or opacities on the corneal endothelium

Question 60

Iris Melanoma in the Cat; Basics, Treatment

Answer 60

o iris freckles -> melanosis -> melanoma
o Diffuse iris melanoma is malignant and appears as dark, smooth, velvety
o As the tumor progresses, glaucoma will develop
o can metastasize via the iridocorneal angle
o melanoma can be monitored until inflammation, glaucoma or tumor approaches the peripheral iris

Treatment
o Enucleation

Question 61

Uveal (iris/ciliary) Melanoma in the Dog; Basics, Treatment

Answer 61

o usually benign but catastrophic to the eye.

Treatment
o focal and involve <25% of the iris may be surgically excised by partial iridectomy
o Melanomas of the iris face may respond temporarily to diode laser
o Once glaucoma occurs enucleation

Question 62

Uveitis; Clinical Signs

Answer 62

o Blepharospasm
o Photophobia
o Miosis
o Hypotony (low IOP)
o Conjunctival hyperemia
o Episcleral injection
o Epiphora
o Corneal edema
o Corneal vascularization
o Flare
o Iris hyperemia
o Hyphema

Question 63

Keratic Precipitates

Answer 63

o sign of chronic uveitis
o inflammatory cells, fibrin, or pigment deposits on corneal endothelium

Question 64

Pigmentary Uveitis; Basics, Treatment

Answer 64

o In any age group, pigment dispersion occurs on the anterior lens capsule
o subsequent development of posterior synechia, cataracts and glaucoma
o not painful
o very little inflammation
o Vision is often lost
o Trans-illuminating uveal cysts are early indication in the Golden Retriever

Treatment
o daily topical prednisolone & atropine used to delay onset of glaucoma.
o if glaucoma -> anti-glaucoma drugs & atropine discontinued

Question 65

Uveodermatologic Syndrome; Basics, Clinical Signs, Diagnosis

Answer 65

o immune mediated disease
o Akitas and Arctic breeds mostly

Clinical signs
o anterior uveitis
o hyphema
o uveal depigmentation
o retinal separation/detachment
o blindness
o secondary glaucoma.
o vitiligo of eyelids, nasal planum, lips, perineum, and footpads

Diagnosis
o skin biopsy

Question 66

Uveitis; Diagnosis, treatment

Answer 66

Diagnosis
o CBC/chem/UA,
o Infectious dz titers
o Chest x-rays and abdominal ultrasound
o Aqueous centesis (sometimes definitive)
o histopathology of the globe.

Treatment
o topical pred or dex
o diclofinac or flubiprofen (use in cat instead of steroids)
o atropine ointment
o systemic antibiotics (if infectious dz)
o topical antibiotics (if intraocular infection)
o systemic anti-fungals (if fungal)
o tramadol for dogs
o bupenorphine in cats

Question 67

Retinal Anatomy

Answer 67

o innermost layer of the eye
o 10 layers

Question 68

Retinal Detachment; Basics, Clinical Signs, Treatment, prognosis

Answer 68

o The retinal pigmented epithelium is the outer retinal link between the rods and cones and is the site of retinal detachment
o photoreceptors are separated from the RPE due to accumulation of fluid or cells -> vision loss.
o On fundic exam, these areas of detachment will appear dull, fuzzy and out of focus.

Clinical Signs
o Dilated pupils not responsive to light.
o If unilateral, the affected pupil will constrict from consensual input (Marcus-Gunn pupil).
o retinal vessels may be seen just behind lens
o retina will appear to be out of focus
o tapetal area appears dull due to fluid between the retina and tapetum

Treatment
o underlying cause
o steroids if infectious dz not present
o Sx for retinal tears

Prognosis
o vision can be restored w/n 4-6wks if retina reattaches in 2wks

Question 69

Retinal Dysplasia

Answer 69

o seen by 6-8 weeks of age
o Folds or rosettes due to defective development of retinal layers
o hereditary disorder
o animals should not be bred

Question 70

Collie Eye

Answer 70

o choroidal hypoplasia
o Tortuous retinal vessels
o Coloboma - a ‘hole’ in the retina or optic nerve
o can cause blindness

Question 71

Progressive Retinal Atrophy; Basics, Clinical Signs

Answer 71

o several hereditary rod/cone degenerative diseases

Clinical Signs
o night blindness that progresses to total blindness
o tapetal hyper-reflectivity
o optic nerve atrophy
o bilaterally symmetrical

Question 72

Optic Nerve Hypoplasia Vs Micropapilla

Answer 72

Optic Nerve Hypoplasia
o congenitally small optic nerve; these patients are blind

Micropapilla
o congenitally small optic nerve, but in a visual eye

Question 73

Papilledema

Answer 73

o passive swelling of optic nerve
o associated with brain tumor or increase CSF pressure.
o nerve is raised but not hyperemic
o Vision is not lost with edema alone

Question 74

Optic Neuritis; Clinical Signs

Answer 74

Clinical Signs
o acute blindness,
o dilated pupils
o sluggish, if any, pupillary response
o fundus may be normal or the optic nerve may be swollen, fuzzy and hyperemic
o normal ERG

Question 75

Acute Blindness; Causes, Diagnosis

Answer 75

Causes
o glaucoma
o retinal detachment
o rapid onset diabetic cataracts
o SARDS (normal fundus & retina)
o optic neuritis. (normal fundus & retina)

Diagnosis
o IOP
o ocular exam
o dilated, non-responsive, or sluggish pupils - lesion in the retina or optic nerve
o normal PLR’s - central lesion (not reliable for diagnosis)
o CATS with normal fundus - lesion is central

Question 76

Sudden Acquired Retinal Degeneration Syndrome (SARDS); Clinical Signs, Signalment, Diagnosis, Treatment

Answer 76

Clinical Signs
o recent weight gain,
o PU/PD/PP
o 50% of dogs’ lab work is consistent with hyperadrenocorticism
o History of acute blindness or vision loss over a few days to weeks
o Inappropriately dilated pupils (often sluggish response)
o Fundus appears normal in early stages

Signalment
o Female, Middle-age

Diagnosis
o ERG (electroretinogram) w/ NO response

Treatment
o no effective treatment at this time to restore vision

Question 77

Hypertension & Retinal Detachment; Basics, Treatment

Answer 77

o BP >180mmHg
o common in geriatric cats with renal failure and/or hyperthyroidism
o geriatric dogs with DM, hyperthyroidism, paraneoplastic, HAC, pheochromocytoma or primary hypertension.

Treatment
o Rapidly decrease the BP
o treat underlying cause of hypertension
o Cats: Amlodipine
o Dogs: Amlodipine/enalapril based on patient

Question 78

Feline Glaucoma; Types

Answer 78

Primary glaucoma
o not common
o can be senile change

Secondary glaucoma
o commonly occurs with uveitis, intraocular neoplasia, hemorrhage and lens luxation.

Aqueous misdirection syndrome:
o unique to the cat
o Aqueous is directed into the vitreous through a rent in the vitreal face,
o lens/iris anteriorly displaced -> very shallow anterior chamber
o may be response to Dorzolamide/Timolol
o lens removal may be necessary

Question 79

Feline Glaucoma; Treatment

Answer 79

o Dorzolamide/Timolol
o use caution if cardiac or respiratory disease exists.
o Steroids are NOT appropriate treatment for glaucoma.

Question 80

Feline Eosinophilic Conjunctivitis; Basics, Diagnosis, Treatment

Answer 80

o likely associated with herpes virus or any chronic inflammatory disease
o not commonly seen without corneal disease
o thickened conjunctiva
o copious ocular discharge

Diagnosis
o even one eosinophil on cytology

Treatment
o variable (personal preference of attending ophthalmologist)
o mast cell inhibitors (Ketotifen),
o cyclosporine,
o oral antihistamines

Question 81

Feline Herpes Virus; Basics, Clinical Signs, Diagnosis

Answer 81

o most common cause of conjunctivitis in the cat
o >90% of cats have FHV 1 (as carrier or active disease)
o Kittens are infected at birth or neonatal life
o remains latent in CN V until stress causes conjunctivitis, keratitis, uveitis
o Feline vaccine FVRCP injectable vaccine does not protect against ocular disease (intranasal may)

Clinical signs
o mild intermittent epiphora, or chronic brown waxy discharge to marked blepharospasm with severe chemosis and hyperemia
o kittens have URI (rhinotracheitis) that includes conjunctivitis.
o Dendritic ulcers are pathognomonic for herpes keratitis

Diagnosis
o Cytology of the discharge will be mostly neutrophils
o chronic cases lymphocytes and plasma cells may be found.
o viral isolation, PCR, IFA is not helpful
o Magnification and a cobalt filter in a dark room

Question 82

Eosinophilc Keratitis; Bascis, Treatment

Answer 82

o raised white plaques
o neutrophils & eosinophils on cytology

Treatment
o Topical cyclosporine
o topical mast cell blockers (ketotifen)
o Topical steroids suppress clinical signs, but may cause FHV-1 ulcers & signs recur when steroid use is discontinued
o Oral megesterol is very effective but causes diabetes and mammary metaplasia

Question 83

Feline Herpes Keratitis; Treatment

Answer 83

o Oral lysine
o oral famcyclovir
o Topical trifluoridine
o Terramycin or erythromycin topically
o Doxycycline orally (benefit in corneal healing)
o buprenorphine, atropine, and/or topical morphine
o Intra-nasal FVRC vaccine
o Avoid stress

Question 84

Corneal Sequestrum; Basics, Treatment

Answer 84

o Dead” or necrotic corneal tissue
o dark brown or black plaque or an amber/brown hue in the cornea with an ulcerated rim around it
o mostly a feline disease but also in horses & dogs.
o often a sequela to herpes keratitis, chronic corneal ulcer or chronic corneal irritant
o painful
o may perforate the cornea.

Treatment
o keratectomy and graft (referral procedure).
o Treat as herpetic ulcerative keratitis and hope it sloughs before it perforates!

Question 85

Post traumatic sarcoma

Answer 85

o highly malignant/metastatic tumor found in cats
o months-years after severe ocular trauma (especially lens)

Question 86

Feline Uveitis; Treatment

Answer 86

o Bartonella – doxycycline or azithromycin
o Toxoplasmosis – clindamycin
o Herpes – lysine/antivirals/IN vaccine
o Mycotic infection – fluconazole other –azole
o Topical Diclofenac
o Topical pred (use very carefully or avoid)
o Atropine ointment to reduce pain and prevent senychia

Question 87

Nuclear Sclerosis; Basics, Age of Onset

Answer 87

o normal aging process
o loss of transparency of lens due to compression and dehydration of the nucleus
o appears as cloudy, hazy, blue or grey
o patient can see through it but more light is required
o Advanced nuclear sclerosis may become dense enough to become a cataract

Normal time of onset of nuclear sclerosis:
o Dogs- over 6 years
o Cats – over 9 years
o Horses – over 15 years

Question 88

Cataracts; Basics, Age of Onset, Types

Answer 88

o Any opacity in the lens.

Age of onset:
o Congenital- present at birth
o Juvenile- 2-6 years
o Senile – over 6 years

Types
o Incipient – Very small opacity, not likely noticed by owner (<15%)
o Immature – Easily visible, but not completely formed, fundus reflex present
o Mature – Fully formed cataract – no fundus reflex can be seen through it
o Hypermature - Cataract starts to contract, liquefy; lens capsule wrinkling; causes LIU

Question 89

Diabetic Cataracts; Basics, Pathophysiology in Dogs

Answer 89

o can occur quite rapidly and sometimes causes the lens capsule to rupture
o 50% DM dogs have cataracts within 6 months of diagnosis & 75% within 1 year.
o should be started on anti-inflammatories & referred immediately

Pathophysiology in Dogs
o elevated serum glucose causes ->
o increase in aqueous glucose enters the lens ->
o overwhelms the normal metabolic pathway ->
o shunted via aldose reductase -> sorbitol. ->
o creates osmotic gradient drawing water into the lens ->
o lens fiber swelling and cataract formation

Question 90

Lens Induced Uveitis; Basics, Treatment

Answer 90

o Often a result of cataracts

Treatment
o topical pred or topical flurbiprofen or diclofenac
o atropine
o systemic pred or NSAID (carprofen, meloxicam etc.).
o Phacoemulsification (may be only way to control inflammation)

Question 91

Lens Luxation/Subluxation; Primary Vs Secondary, Anterior Vs Posterior

Answer 91

Primary:
o breed associated (Jack Russell Terrier, most terrier breeds, Heelers)
o gene affects the protein integrity of the lens zonules causing luxation.

Secondary
o Trauma, glaucoma, chronic uveitis

Anterior lens luxation
o emergency!
o usually very painful
o may cause irreversible damage to the corneal endothelium, and/or secondary glaucoma

Posterior lens luxation
o may cause pain and inflammation
o not a surgical emergency
o Miotics should be used to keep the lens in the posterior segment.
o If uncontrolled glaucoma develops enucleation is indicated.

Question 92

Glaucoma; Basics, Clinical Signs

Answer 92

o damage to the retinal ganglion cells and optic nerve due to increased IOP
o always due to reduced outflow of fluid, not increased production
o can be inherited or due to other ocular dz

Clincial Signs
o Enlarged globe (buphthalmos)
o Loss of vision
o Episcleral injection (deep vessels)
o Corneal edema
o Dilated pupil, non responsive
o Striae (linear breaks in the endothelium)
o Blepharospasm

Question 93

Acute Glaucoma; Basics, Treatment, What if uveitis is present

Answer 93

o Treated as an emergency
o Rapidly decrease IOP
o Refer

Treatment
o Dorzolamide/Timolol
o Latanoprost (DO NOT use w/ anterior lens luxation)
o IV Mannitol If IOP > 40mmHg, and pressure does not respond to Dorzolamide/Timolol or Latanoprost,
o IV Solu–Medrol ONCE
o amlodipine for 10 days
o Oral pain meds

Concurrent Uveitis
o AVOID latanoprost, mannitol, atropine
o oral NSAID
o topical Pred if no corneal ulceration
o Diclofenac if corneal ulcer is present.

Question 94

Chronic Glaucoma; Basics, Clinical Signs, Treatment

Answer 94

o not an emergency
o painful condition

Clinical Signs
o Buphthalmia
o Corneal edema
o Dilated pupil – absent PLR
o Absent menace
o Pain **
o Episcleral injection
o Corneal striae
o Retinal degeneration (hyperreflectivity, vascular attenuation)
o Cupped optic disc

Treatment
o Enucleation (definitive)
o Evisceration with prosthesis (negative side effects)
o Pharmacologic ablation of ciliary body (worst choice)

Question 95

Multiple ocular abnormalities in Equine; Basics, Clinical Signs

Answer 95

o syndrome associated w/ the silver dapple gene
o most severely affected have brown coat & white mane/tail.

Clinical Signs
o megalocornea
o iris hypoplasia
o pupil that is refractory to dilation
o temporary cysts affecting iris, ciliary body or peripheral retina
o retinal detachment/ dysplasia
o cataracts

Question 96

Congenital Stationary Night Blindness in Horses; Basics, Clinical Signs

Answer 96

o non-progressive night blindness
o Appaloosas w/ Lp gene

Clinical Signs
o eye morphology is normal
o fundus will appear normal
o ERG is abnormal due to transmission defect in the retina

Question 97

Nasal-lacrimal duct atresia in horses; Basics, Clinical Signs, Diagnosis, Treatment

Answer 97

o developmental defect
o can be anywhere along the duct

Clinical Signs
o may not appear for 1-2 yrs
o epiphora
o purulent discharge (dacryocystitis)

Diagnosis
o nasal-lacrimal (N-L) flush antegrade and retrograde
o location and length of the defect identified with contrast imaging

Treatment
o Surgical correction of the defect challenging / impossible

Question 98

Normal Foal Eyes

Answer 98

o born w/ eyes open and visual at birth
o Subconjunctival hemorrhage or episcleral injection may be present at birth but should resolve in 7-10d
o may have slight ventromedial strabismus early
o pupil is initially more round first 2 wks
o may be prominent Y-sutures in the lens

Question 99

Neonatal Maladjustment Syndrome in Foals; Ocular Signs, Treatment of Ocular Issues

Answer 99

Ocular Signs
o microphthalmia,
o entropion
o secondary corneal ulcers.

Treatment
o entropion temporarily corrected with vertical mattress tacking sutures
o corneal ulcers treated w/ topical antibiotic (NPB) ointment

Question 100

Neonatal Septicemia in Foals; Clinical Signs, Treatment

Answer 100

Clinical Signs
o Uveitis
o green hue seen due to fibrin
o episcleral injection
o miosis
o hyperemia
o flare
o retinal scarring after healing (can affect vision)

Treatment
o systemic treatment fro septicemia
o topical NSAID (diclofenac or flurbiprofen)
o topical ofloxacin or chloramphenicol
o atropine (use cautiously - can cause ileus)

Question 101

Parasitic Ocular Dz in Horses; Basics, Diagnosis, Treatment, Prevention

Answer 101

o Habronema
o Onchoceriasis

Diagnosis
o biosy

Treatment
o ivermectin
o systemic and topical NSAID or steroid (determined by severity)

Prevention
o fly mask
o regular deworming
o fly population control

Question 102

Eosinophilc Ocular Dz in Horses; Basics, Clinical Signs, Diagnosis, Treatment

Answer 102

o very challenging to treat.

Clinical Signs
o granulomas in the eyelids
o eosinophilic, ulcerative plaques on the cornea or conjunctivitis
o eosinophilic exudate.

Diagnosis
o Cytology of ocular discharge w/ eosinophils and neutrophils
o corneal cytology w/ eosinophils and neutrophils
o Biopsy of eyelid mass

Treatment
o specific for each case
o systemic NSAIDS or steroids
o antihistamine orally (Cetirizine) and topically (ketotifen)
o intralesional steroid & antibiotic
o topical NSAID or steroid
o Eosinophilic plaques often require superficial keratectomy

Question 103

Eosinophilic keratitis in Horses; Clinical Signs, Diagnosis, Treatment

Answer 103

Clinical Signs
o raised white plaques

Diagnosis
o eosinophils on cytology.

Treatment
o can be frustrating
o systemic antihistamines
o topical cyclosporine,
o topical antihistamine (ketotifen)
o topical antibiotics
o topical steroids (if NO ulcer)
o Corneal sequestra require keratectomy

Question 104

Melting Corneal Ulcers in Horses; Basics, Treatment

Answer 104

o more common in the horse than in other species

Treatment
o Anti-collagenase (serum, terramycin, EDTA) through sub-palpebral lavage hourly.
o BNP, chloramphenicol, terramycin or ciprofloxacin
o Oral doxycyline
o Atropine to effect
o Flunixin
o surgical excision and conjunctival or amnion graft if they fail to improve/worsen

Question 105

Equine Recurrent Uveitis; Basics, Clinical Signs, treatment

Answer 105

o serious and common dz
o Appaloosa over-represented
o immune-mediated
o often associated with lepto

Clinical Signs
o chronic or recurring uveitis
o atrophy of corpora nigra,
o depigmentation of the iris,
o pigment on the endothelium or lens capsule,
o retinal scarring (butterfly lesion)
o cataracts,
o lens luxation/subluxation
o secondary glaucoma
o loss of vision
o no overt pain

Treatment
o atropine to effect
o topical steroids (Dexamethasone or prednisolone acetate)
o systemic NSAIDS (flunixin or phenylbutazone)
o Diclofenac or flurbiprofen instead of topical steroids if corneal ulcer
o doxycycline if lepto positive
o suprachoroidal cyclosporine implant long-term

Question 106

HIK (heterochromic iridocyclitis/keratits) in Horses; Clinical Signs, Treatment

Answer 106

Clinical Signs
o insidious uveitis
o iris depigmentation
o free pigment in the aqueous and on the endothelium

Treatment
o aggressive uveitis treatment may slow the progression to glaucoma

Question 107

Equine Motor Neuron Dz

Answer 107

o neurologic disease
o caused by vitamin E deficiency
o pathognomonic retinal lesions