Ophthalmic Diseases

Chapter 4

Common Diseases of Companion Animals

Pupil Iris Sclera Conjunctiva

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)

– 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

• Rx– Topical antibiotic ointment

• neomycin/bacitracin/polymyxin B• Gentamicin ophthalmic ointment• Antibiotic w/ cortisone (if cornea is intact)

• Client info– 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

Conjunctivitis

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

• Signs– Watering of eye– Discoloration of hair

• Dx– Fluorescein dye test

• Dye at nose shows duct is open

• Rx– Treat 1º cause

• 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

Epiphora

EntropionEye 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– Epiphora (tearing)– Chemosis (swelling of conjunctiva)– Conjunctivitis– Pain– Corneal ulceration (±)– Photophobia

• 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

Entropion

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• Neoplasia• Luxation of lens• Hemorrhage• Uveitis

• Signs– 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– Trauma– Chemical burns– Foreign objects– KCS (Keratoconjunctivitis Sicca)– Conformational abnormalities– Herpes virus (cats)

• Signs– Pain– Epiphora– Blepharospasm (eyelid spasm)– Hyperemia of conjunctiva

• Dx—Fluorescein dye to cornea

Herpes virus

• 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– 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

Ulcerative Keratitis(Corneal Ulcers)

Chronic Superficial Keratitis (Pannus)

Pannus—superficial corneal vascularization/scar tissueProgressive, bilateral, can result in blindness

• Cause– Thought to be immune-mediated(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

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

Chronic Superficial Keratitis (Pannus)

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– 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

• 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

• 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

Progressive Retinal Atrophy

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

• 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