Exam1 Notes Flashcards
Requirements for Vision
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
Vision in Domestic Animals
o superior night vision due to more rods & tapetum
o decreased visual acuity due to less cones
Menace response
o vision (CNII)
o trigeminal (CNV)
o facial (CNVII)
o central pathway
Third Eyelid
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
Which Species Do Not have a Tapetum?
pig, camelids, some birds
Layers of the Eye
Outer fibrous tunic
o cornea
o sclera
Middle vascular (uvea)
o iris
o ciliary body
o choroid
inner nervous layer
o retina
Dermoid; basics, treatment
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
Eyelid Agenesis; Basics, Treatment
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
Ophthalmia Neonatorum; Basics, Treatment
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.
Entropion; Basics, Treatment
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
Acquired Entropion; Basics, Treatment
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.
Ectropion; Basics, Clinical Signs, Treatment
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!!
Distichiasis; Basics, Treatment
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)
Ectopic Cilia; Basics, Clinical Signs, Treatment
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
Trichiasis; Basics, Treatment
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.
Eyelid Laceration; Basics, Treatment
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
Eyelid Tumors; Basics, Treatment
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
Eyelid Sx Guidelines
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
Blepharitis; Basics
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.
Cherry Eye (Prolapsed Gland of the 3rd Eyelid); Basics, Treatment
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)
Follicular Conjunctivitis; Basics, Treatment
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
Scrolled Cartilage; Basics, Treatment
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
Neoplasia of the 3rd Eyelid; Basics, Diagnosis, Treatment
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
Tears; Function, Flow
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
Tear Components
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
Imperforate Puncta; Basics, Clinical Signs, Treatment
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)
Nasal-lacrimal Obstruction; Basics, Clinical Signs
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
Dacryocystitis; Basics, Treatment
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
Meibomian gland adenitis; Basics, Treatment
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
Normal STT Values for Dog, Cat, Horse
o Dog = 15 – 25 mm/min.
o Cat = highly variable
o Horse = highly variable 10 to >30mm/min.
Keratoconjunctivitis sicca - KCS –“DRY EYE”; Basics, Clinical Signs, Treatment
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)
Basics of the Conjunctiva
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
Conjunctivitis; Basics, Clinical Signs, Causes
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
Conjunctivitis; Diagnostic Steps
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)
Allergic Conjunctivitis
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
Corticosteroids Used in the Eye
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.
Corneal Ulcers; Clinical Signs, Diagnosis
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
Equine Conjunctivitis; Causes, Treatment
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
Cornea; Function & Anatomy
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
Stroma; Function & Anatomy
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)
Descemet’s membrane; Function & Anatom
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.
Corneal Edema; Basics, Causes of Focal Vs Generalized
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)
Endothelial Dystrophy of the Cornea; Basics, Treatment
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)
Lipid Dystrophy of the Cornea; Basics, Treatment
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
Superficial Corneal Ulcer in Dogs; Healing & Treatment
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
Superficial Corneal Ulcer in Cats; Healing & Treatment
o same as dogs
o accept NO BNP
o use erythromycin or terramycin as antibiotic
Indolent Ulcers; Basics
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
Indolent Ulcers; Treatment in dogs
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
Deep Stromal Ulcer; Basics
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
Descemetocele; Basics, Treatment
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
Melting Ulcers; Basics
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
Melting Ulcers; Treatment
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
Stromal Abscess; Basics, treatment
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
German Shepherd Pannus; Basics
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
Pannus; Treatment
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
Pigmentary Keratitis; Basics, Treatment
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
Corneal Neoplasia; Basics, Treatment
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
Limbal Melanomas; Basics, Treatment
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
Persistent Pupillary Membranes (PPMs); Basics
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
Iris Melanoma in the Cat; Basics, Treatment
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
Uveal (iris/ciliary) Melanoma in the Dog; Basics, Treatment
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
Uveitis; Clinical Signs
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
Keratic Precipitates
o sign of chronic uveitis
o inflammatory cells, fibrin, or pigment deposits on corneal endothelium
Pigmentary Uveitis; Basics, Treatment
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
Uveodermatologic Syndrome; Basics, Clinical Signs, Diagnosis
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
Uveitis; Diagnosis, treatment
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
Retinal Anatomy
o innermost layer of the eye
o 10 layers
Retinal Detachment; Basics, Clinical Signs, Treatment, prognosis
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
Retinal Dysplasia
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
Collie Eye
o choroidal hypoplasia
o Tortuous retinal vessels
o Coloboma - a ‘hole’ in the retina or optic nerve
o can cause blindness
Progressive Retinal Atrophy; Basics, Clinical Signs
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
Optic Nerve Hypoplasia Vs Micropapilla
Optic Nerve Hypoplasia
o congenitally small optic nerve; these patients are blind
Micropapilla
o congenitally small optic nerve, but in a visual eye
Papilledema
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
Optic Neuritis; Clinical Signs
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
Acute Blindness; Causes, Diagnosis
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
Sudden Acquired Retinal Degeneration Syndrome (SARDS); Clinical Signs, Signalment, Diagnosis, Treatment
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
Hypertension & Retinal Detachment; Basics, Treatment
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
Feline Glaucoma; Types
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
Feline Glaucoma; Treatment
o Dorzolamide/Timolol
o use caution if cardiac or respiratory disease exists.
o Steroids are NOT appropriate treatment for glaucoma.
Feline Eosinophilic Conjunctivitis; Basics, Diagnosis, Treatment
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
Feline Herpes Virus; Basics, Clinical Signs, Diagnosis
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
Eosinophilc Keratitis; Bascis, Treatment
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
Feline Herpes Keratitis; Treatment
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
Corneal Sequestrum; Basics, Treatment
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!
Post traumatic sarcoma
o highly malignant/metastatic tumor found in cats
o months-years after severe ocular trauma (especially lens)
Feline Uveitis; Treatment
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
Nuclear Sclerosis; Basics, Age of Onset
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
Cataracts; Basics, Age of Onset, Types
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
Diabetic Cataracts; Basics, Pathophysiology in Dogs
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
Lens Induced Uveitis; Basics, Treatment
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)
Lens Luxation/Subluxation; Primary Vs Secondary, Anterior Vs Posterior
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.
Glaucoma; Basics, Clinical Signs
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
Acute Glaucoma; Basics, Treatment, What if uveitis is present
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.
Chronic Glaucoma; Basics, Clinical Signs, Treatment
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)
Multiple ocular abnormalities in Equine; Basics, Clinical Signs
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
Congenital Stationary Night Blindness in Horses; Basics, Clinical Signs
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
Nasal-lacrimal duct atresia in horses; Basics, Clinical Signs, Diagnosis, Treatment
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
Normal Foal Eyes
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
Neonatal Maladjustment Syndrome in Foals; Ocular Signs, Treatment of Ocular Issues
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
Neonatal Septicemia in Foals; Clinical Signs, Treatment
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)
Parasitic Ocular Dz in Horses; Basics, Diagnosis, Treatment, Prevention
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
Eosinophilc Ocular Dz in Horses; Basics, Clinical Signs, Diagnosis, Treatment
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
Eosinophilic keratitis in Horses; Clinical Signs, Diagnosis, Treatment
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
Melting Corneal Ulcers in Horses; Basics, Treatment
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
Equine Recurrent Uveitis; Basics, Clinical Signs, treatment
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
HIK (heterochromic iridocyclitis/keratits) in Horses; Clinical Signs, Treatment
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
Equine Motor Neuron Dz
o neurologic disease
o caused by vitamin E deficiency
o pathognomonic retinal lesions
