Chapter 4 Common Diseases of Companion Animals Ophthalmic Diseases Chapter 4 Common Diseases of Companion Animals

Ophthalmic Diseases The cornea has no blood supply but has nerve endings. The outer layer is corneal epithelium which heals quickly when damaged. Descemet’s membrane is the innermost membrane of the cornea. The choroid contains blood vessels, lymph, and pigment. It stretches around to the ciliary bodies which make aqueous humor in the anterior chamber. The ciliary bodies have processes on them that attach to the lens that push or pull on the lens when focusing an image.

Conjunctivitis Causes of conjunctivitis Allergies CONJUNCTIVA: pink tissue that lines the inner surface of the eyelids and covers the front portion of the eyeball except for the cornea Causes of conjunctivitis Allergies Poor anatomy (ectropion, entropion) Bacterial infection secondary to: Injury ↓Tear production Foreign body Respiratory disease (Herpes virus, calicivirus, mycoplasma, chlamydia)

Redness, chemosis(congested/swollen), painful, ocular discharge

Conjunctivitis Diagnosis Determine the primary disease: Rule out a foreign body Rule out ‘dry eye’ in chronic cases Schirmer tear test Numb the eye and explore the conjunctiva with a dry q-tip to look for FB Below 10 on STT is indicative of decreased tear production

SCHIRMER TEAR TEST

Conjunctivitis Treatment Client info Topical antibiotic ointment neomycin/bacitracin/polymyxin B (BNP or triple antibiotic) Antibiotic ointment w/ cortisone (only if no corneal ulcer present) Client info Keep medial canthus of eye clean (warm water, clip hair) Vaccinate kittens to prevent URI Do not touch eye with applicator of eye ointment Discard unused medication Fluffy faced dogs and grooming

Epiphora EPIPHORA: excessive tearing Causes: Overproduction of tears Ocular pain, irritation from hair, etc. Faulty drainage of tears by lacrimal system Blockage of duct Blockage of puncta Imperforate puncta (no opening)

Epiphora Watery eyes Staining of fur around eyes

Epiphora Diagnosis Physical exam Fluorescein dye test for patency of duct Dye draining at nose indicates duct is patent

EPIPHORA Treatment Treat primary cause Flush lacrimal ducts if blocked Surgically open imperforate puncta Topical antibiotic ointment for infection Keep hair trimmed around eyes

EPIPHORA Client info Staining due to pigment in tears can be resolved Some dogs have life-long problem FLUSHING THE NASOLACRIMAL DUCT

EPIPHORA Client info Staining due to pigment in tears can be resolved with topical and/or medical management Some dogs have life-long problem due to chronic infection or abnormal conformation

Entropion: eyelids that roll in against the cornea Causes Congenital Trauma causing scarring and distortion of lid Severe blepharospasm from pain Signs Epiphora Chemosis Conjunctivitis Pain Corneal ulceration (±) Photophobia

Entropion Treatment Surgical correction is treatment of choice Temporary mattress suture to evert eyelid (young animal) Lateral canthoplasty to shorten eye lid Hotz-Celsus: Remove elliptical piece of tissue from under eye

Hotz-celsus technique https://youtu.be/qaeWCtg1hzc

Ectropion Causes Signs Treatment Congenital Over-correction of entropion Signs Conjunctivitis Epiphora Keratitis (corneal inflammation/scarring) Treatment Surgery to shorten eye lid

Hypertrophy and Prolapse of 3rd eyelid gland

Prolapse of Nictitans Gland (Cherry Eye) Nictitating membrane(3rd eyelid) is a protective structure and produces ~30% of tears Signs Young dog (<2 y) Epiphora Usually no pain Diagnosis Rule out tumor in older dogs and cats Treatment Sx to remove gland is an option , but not recommended Suture back in place

Cherry eye surgery https://youtu.be/pGLJyFi2YAA

Glaucoma GLAUCOMA: increased intraocular pressure due to excess production or decreased drainage of aqueous humor aqueous humor provides nourishment to lens and cornea Normally, the amt of fluid produced = amt of fluid leaving eye Normal intraocular pressure: Dog/Cat—12-22 mm Hg Signs Ocular pain Corneal edema Dilated pupil (unresponsive to light) Blind (±) Name of instrument used to measure intraocular pressure?

Glaucoma Causes Inherited Secondary - obstruction of drainage angle Neoplasia Luxation of lens Hemorrhage Uveitis (inflammation of ciliary body, iris, choroid)

Glaucoma

Glaucoma Diagnosis IOP >30 mm Hg Schiotz Tonometer Tono-Pen

Glaucoma Treatment Acute - EMERGENCY Latanoprost (Xalatan 0.005%)- Facilitates aqueous outflow Dichlorphenamide (Daranide) - Decreases aqueous production Surgical Cryosurgery or laser -destroys part of ciliary body to decrease aqueous production Chronic Enucleation to relieve pain

Ulcerative Keratitis(Corneal Ulcers) Causes Trauma KCS (Keratoconjunctivitis Sicca) Herpesvirus (cats) Signs Pain Epiphora Blepharospasm (eyelid spasm)

Corneal Ulcers Diagnosis: Fluorescein Dye Test

Corneal Ulcers Treatment Topical atropine (1%) ointment – pupil dilation Decrease pain, blepharospasm antibiotic or antiviral ointments or solutions Surgery Eyelid flap, conjunctival flap Serum (autologous/autogenous) Blocks proteases released from leukocytes and bacteria keep in refrigerator (throw out after 72 hours)

Deep Corneal Ulcer Desmetocele – erosion to membrane

Corneal Ulcers Client info Most ulcers heal quickly with treatment Avoid using old medications No ointment w/cortisone! will inhibit healing of ulcer Do not touch eye with ointment applicator

Chronic Superficial Keratitis (Pannus) Definition: Pannus - superficial corneal vascularization/scar tissue Progressive, bilateral, can result in blindness Cause Thought to be immune-mediated (Infiltration of cornea with lymphocytes, plasma cells) ultraviolet light/high altitudes increases incidence Signs Opaque lesions that begin at limbus and extend into cornea Milky, pink, or tan

Chronic Superficial Keratitis (Pannus)

Chronic Superficial Keratitis (Pannus) Diagnosis Rule out KCS, corneal ulcers Treatment Corticosteroids often lifelong Cyclosporine often lifelong Antibiotic eye ointment Client info No cure If Rx is stopped, disease will return and progress High altitudes and ↑sun predispose animals

DOGGLES!!!!

Keratoconjunctivitis Sicca (KCS) Definition: Lack of tear production tears lubricate, nourish, ↓bacteria, aid in healing Tears from 2 glands: 70%:Lacrimal gland; 30%:Nictitans gland Signs of KCS Recurrent conjunctivitis, corneal ulcers, keratitis Dull, dry, irregular cornea, conjunctiva mucoid ocular discharge Blepharospasm Crusty nares

KCS

KCS Treatment Tear stimulation Artificial tears Client info Drugs: cyclosporine, pilocarpine Artificial tears Client info Prognosis is guarded for resolution Failure to treat → blindness Parotid duct (salivary gland) transposition

Cataracts Definition: Opacity of lens that causes reduced vision; most common disease of lens NOT NUCLEAR SCLEROSIS!! Cause Genetic 2º to: Diabetes mellitus (bilateral; within 1 y of disease; ↑glucose → ↑fluid in lens) Trauma Lens luxation

Cataracts Signs Diagnosis Progressive loss of vision Opaque pupillary opening Diagnosis Must be distinguished from senile nuclear sclerosis Normal old age change; graying of lens; bilateral; usually does not affect sight

Cataracts Treatment Client info Surgical removal of lens Treat underlying cause Client info Most cataracts are inherited, so don’t breed affected dogs Dogs can live quality lives even with bilateral cataracts

Progressive Retinal Atrophy A group of hereditary disorders causing loss of rods, cones, and/or blood supply to the retina Signs - slow onset of blindness Loss of night vision (rods) → loss of day vision (cones) Dx Ophthalmic exam gray, granular appearance of retina Hyperreflective retina Narrow blood vessels, optic nerve atrophy

PROGRESSIVE RETINAL ATROPHY optic nerve atropy and vessel attenuation Normal canine retina

Progressive Retinal Atrophy No Treatment Client info This is an inherited disease Avoid buying affected dogs Have ocular exam by board certified ophthalmologist Blind animals adapt well, but may have trouble in strange surroundings Cats need well balanced diet Taurine deficiency can lead to PRA

Detached retina Usually related to trauma Retina will look “folded” down from back of the eye Animal will appear blind (no PLR) in affected eye No treatment

Proptosed Globe Cause Clinical Signs 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 – Treatment Lubricate immediately Reduce the globe into the socket ASAP to reduce trauma to optic nerve, if the eye is viable Enucleation if optic nerve severed Systemic and topical antibiotics

Proptosed Globe

Prognosis Favorable prognosis Unfavorable prognosis non-brachycephalic brachycephalic dog, Normal PLRs normal findings on ophthalmic exam proptosed eye with vision on initial presentation Unfavorable prognosis non-brachycephalic cat blood in the anterior chamber no visible pupil facial fractures optic nerve damage and/or torn extraocular muscles

References http://www.vetmed.ucdavis.edu/courses/vet_eyes/ http://vanat.cvm.umn.edu/carnLabs/Lab24/Lab24.html Alleice Summers, Common Diseases of Companion Animals http://www.vetmed.wisc.edu/Data/CourseMaterial/Miller/Emergenc ies.pdf