Pupil Iris
Sclera Conjunctiva
Ophthalmic Diseases
Chapter 4
Common Diseases of Companion Animals
Conjunctivitis
• Causes (in dogs, usually not caused by infectious agent)
– Allergy (atopy)
– Anatomic (ectropion, entropion)
– Bacterial infection (predisposed by):
• Injury
• ↓Tear production
• Foreign body
• Causes (in cats, it is usually infectious)
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Feline herpes virus (most common cause of bilateral conjunctivitis)
Calicivirus
Chlamydia psittaci bacteria
Mycoplasma
Conjunctivitis
• Signs
– Redness
– Chemosis (swelling of conjunctiva)
– Ocular discharge (tears, mucus)
• Dx
– Determine 1º disease, if any
– r/o FB
– r/o ‘dry eye’ in recurrent cases
• Schirmer tear test
• 1 min; tears show as blue dye
Conjunctivitis
• Rx
– Topical antibiotic ointment
• neomycin/bacitracin/polymyxin B
• Gentamicin ophthalmic ointment
• Antibiotic w/ cortisone (if cornea is intact)
• Client info
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Do not allow dogs to ride with head out window
Keep medial canthus of eye clean (warm water, clip hair)
Vaccinate kittens to prevent URI
Do not touch eye with applicator
Discard unused medication
Epiphora
Excess tearing
• Causes (2 causes)
– Overproduction of tears
• Ocular pain, irritation (from hair, etc)
– Faulty drainage by lacrimal system
• Blockage of duct (swelling, inflam)
• Blockage of puncta (hair, debris)
• Imperforate puncta (no opening)
– Cockers
– Poodles
• Trauma
Epiphora
• Signs
– Watering of eye
– Discoloration of hair
• Dx
– Fluorescein dye test
• Dye at nose shows duct is open
• Rx
– Treat 1º cause
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Flush lacrimal ducts
Surgically open imperforate puncta
Topical antibiotic ointment
Keep hair trimmed around eyes
• Client info
– Hair acts as wick
– Staining due to pigment in tears, not blood
– Some dogs have life-long problem
Entropion
Eye lids rub against cornea; common in dogs, not in cats
• Causes
– Congenital—large orbits w/ deep-set eyes (poor lid support)
• Collies, G Dane, I Set, Dobe, G Ret, Rott, Weim
– Poor ocular muscle development (also congenital)
• Chesapeake, Labs, Chow, Sam
– Trauma → scarring with distortion of lid
– 2º to painful corneal lesion, conjunctiva inflammation (most common
cause in cats)
• Signs
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Epiphora (tearing)
Chemosis (swelling of conjunctiva)
Conjunctivitis
Pain
Corneal ulceration (±)
Photophobia
Entropion
• Rx
– Surgical correction is TOC
• Temporary mattress suture to evert eye (young animal)
• Lateral canthoplasty (to shorten eye lid)
• Remove elliptical piece of tissue from under eye
Ectropion
• Causes
– Congenital
• Bassets, Blood, C Span, E Bull, St Bern
• Signs
– Conjunctivitis
– Epiphora
– Keratitis (corneal inflammation/scarring), usually from
exposure
– Purulent exudate
• Rx
– Surgery to shorten eye lid
– Other procedures
Hypertrophy of Nictitans Gland
(Cherry Eye)
Nictitating membrane is the 3rd eyelid; is a protective structure
Produces ~30% of tears
• Cause is unknown
– Bassets, Beagle, B Terr, C Span
• Signs
– Young dog (<2 y)
– Epiphora
– Usually no pain
• Dx
– r/o tumor
• Rx
– Sx remove gland
– Stitch back in place
Glaucoma
Aqueous humor provides nourishment to lens and cornea
Increased intraocular pressure; → Blindness
Normally, the amt of fluid produced = amt of fluid leaving eye
Normal: Dog/Cat—12-22 mm Hg
• Causes
– Inherited (C Span, Basset, Chow)
– Secondary—obstruction of drainage angle
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Neoplasia
Luxation of lens
Hemorrhage
Uveitis
• Signs
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Ocular pain
Episcleral injection
Corneal edema
Dilated pupil (unresponsive to light)
Blind (±)
Glaucoma
• Dx
– IOP>30 mm Hg
• Rx
– Acute (this is an emergency; prevent
blindness)
• Latanoprost (Xalatan 0.005%)
– Facilitates aqueous outflow
• Dichlorphenamide (Daranide)
– Decreases aqueous production
• Surgical
– Cryosurgery or laser (destroys part of ciliary body)
» Decreases aqueous production
– Chronic
• Enucleation to relieve pain
Schiotz Tonometer
Tono-Pen
Ulcerative Keratitis
(Corneal Ulcers)
Ulcers usually heal within a few days
• Causes
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Trauma
Chemical burns
Foreign objects
KCS (Keratoconjunctivitis Sicca)
Conformational abnormalities
Herpes virus (cats)
• Signs
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Pain
Epiphora
Blepharospasm (eyelid spasm)
Hyperemia of conjunctiva
• Dx—Fluorescein dye to cornea
Herpes virus
Ulcerative Keratitis
(Corneal Ulcers)
• Rx
– Topical atropine (1%) ointment (Debate over benefits and
how long to use)
• Decrease pain, blepharospasm
– Topical broad-spectrum antibiotic ointment
– Viral ointments or solutions (Viroptic)
– Surgery
• Eyelid flap, conjunctival flap
– Serum (autologous)
• Blocks proteases released from leukocytes and bacteria
(helps prevent continued collagen loss)
– keep in refrigerator (throw out after 72 hours)
Ulcerative Keratitis
(Corneal Ulcers)
• Client info
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Most ulcers heal quickly with treatment
Avoid using old medications
Rx with cortisone will retard healing of ulcer
Do not touch eye with ointment applicator
Chronic Superficial Keratitis
(Pannus)
Keratitis
Pannus—superficial corneal vascularization/scar tissue
Progressive, bilateral, can result in blindness
• Cause
– Thought to be immune-mediated
Pannus
(Infiltration of cornea with lymphocytes, plasma cells)
– Animals living above 5000 ft elevation most susceptible
– Increased ultraviolet light increases incidence
• Signs
– Opaque lesions that begin at limbus and extend into cornea
• Milky, pink, or tan
Chronic Superficial Keratitis
(Pannus)
• Breeds
– G Shep, B Collie, greyhound, S Huskie
• Dx
– r/o KCS, corneal ulcers
• Rx
– Corticosteroids for life
• Client info
– No cure
– If Rx is stopped, disease will return and progress
– High altitudes and ↑sun predispose animals
Deep Corneal Ulcer
• Desmetocele – erosion to membrane
Keratoconjunctivitis Sicca (KCS)
Lack of tear production; tears clean, lubricate, nourish, ↓bacteria, aid in healing
Tears from 2 glands: 70%--Lacrimal gland; 30%--Nictitans gland
• Signs
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Recurrent conjunctivitis, corneal ulcers, keratitis
Dull, dry, irregular cornea, conjunctiva
Tenacious, mucoid ocular discharge
Blepharospasm
Crusty nares
• Rx
– Tear stimulation—cyclosporine, pilocarpine
– Artificial tears
• Client info
– Px is guarded for resolution
– Failure to treat → blindness
Cataracts
Opacity of lens that causes reduced vision; most common disease of lens
• Cause
– Genetic
– 2º to:
• Diabetes mellitus (bilat; within 1 y of disease; ↑glucose → ↑fluid in lens)
– Most common cause
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Trauma (unilateral; HBC, thorn penetration, shotgun pellet)
Lens luxation
Nutritional deficiency
Uveitis
Hypocalcemia
Electrical shock
• Rx
– Surgical removal of lens
– Treat underlying cause (e.g., Diabetes)
• Client info
– Most cataracts are inherited, so don’t breed affected dogs
– Dogs can live quality lives even with bilat cataracts
Cataracts
• Signs
– Progressive loss of vision
– Opaque pupillary opening
• Dx
– Must be distinguished from senile nuclear sclerosis
• Normal old age change; graying of lens; bilat; usu does not affect sight
Progressive Retinal Atrophy
A group of hereditary disorders causing loss of rods, cones, and/or blood supply
• Breeds
– T/min Pood, G Ret, I Set, C Span, Schnauz, Collie, Sam, N Elk
• Recessive gene isolated in some breeds
• Signs—slow onset of blindness
– Loss of night vision → loss of day vision → cataracts (±)
• Dx
– r/o metabolic disorders that could cause cataracts
– Ophth exam
• gray, granular appearance of retina
• Hyperreflective retina
• Vascular attenuation, optic nerve atrophy
Progressive Retinal Atrophy
• Rx
– None
• Client info
– This is an inherited disease
– Avoid buying affected breeds
• Have ophth exam by board certified ophth to r/o PRA
– Blind animals adapt well
• Have trouble in strange surroundings
– Cats need taurine supplemented food to avoid
retinal degeneration
Anterior Uveitis
• Inflammation of uvea
• Causes
– Inflammation/infection – FeLV/FIP, fungal,
bacterial
– Neoplasia
– Trauma
Uveitis – Clinical Signs
• Blepharospasm
• Aqueous flare – increased turbidity of aqueous
humor
• Miosis of affected eye
• Iridal swelling or congestion
• Keratic precipitates
• Ciliary flush in limbal region
• +/- Corneal edema
• +/- hyphema
Anterior Uveitis – hyphema
Anterior Uveitis
Anterior Uveitis – keratic
precipitates
Anterior Uveitis – Treatment
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Topical steroids
Topical Antiinflmmatory drugs (ocufen)
Subconjunctival steroids
Systemic steroids
Atropine – dilates eye, decreases pain
Antibiotics – topically +/- systemically
Anterior Uveitis – Client Info
• Recheck within 3 days
• Secondary glaucoma is frequent
complication
• Prognosis depends on cause
• Treat for 2 months regardless of cause –
blood-aqueous barrier disrupted for 6
weeks
Proptosed Globe
• Cause
– Trauma
– Conformation
– Retrobulbar abscess or neoplasia
• Clinical Signs
– Protrusion of the globe,
– Eyelids unable to close, may be trapped
behind globe
Proptosed Globe
Proptosed Globe
Proptosed Globe – Treatment
• Lubricate immediately
• Reduce the globe into the socket ASAP to
reduce trauma to optic nerve
• Enucleation if optic nerve severed
• Systemic and topical antibitics
• +/- Steroids
Proptosed Globe