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Diseases of the Eye Casey Conway Jeannie Stall , R.V.T. & ??? Credits : Clip Art graphics/Google images The Eye • • • • • CDCA has great picture of a cross section.(hint) Most highly developed of all senses Most pets can live quality lives with a vision loss Proper diagnosis, quick treatment – Essential! 3 main categories of eye diseases: ▫ Accessory structures ▫ The globe ▫ The retina and the neural pathways Anatomy Credits: ukvetsonline Diseases of the Accessory Structures • Eyelids, conjunctiva, tear ducts, third eyelid, lacrimal glands • Red eyes, blepharospasm (squinting), ocular discharge • Common causes: Trauma & infection • Conjunctivitis/Epiphora(overflow of tears)/ KCS (Keratoconjunctivitis sicca)/Cherry Eye Conjunctivitis • Inflammation of the conjunctiva • Rarely a primary dz process • Canine: can be non-infectious or infectious Feline : is primarily infectious ▫ ▫ ▫ ▫ FHV – seen w/ Upper Resp. Tract symptoms Calicivirus Chlamydia psittaci Mycoplasmas Conjunctivitis cont’d • Clinical signs ▫ Chemosis (swelling) ▫ Hyperemia (redness) ▫ Ocular discharge ▫ +/- signs of URT dz • Dx ▫ PE (thorough exam of conjunctiva/foreign body) ▫ Schirmer Tear Test, conj. scraping (cytology, c & s) • Tx: ▫ Resolve underlying systemic dz. ▫ Topical antibiotic ointments/drops ▫ Nonsteroidal oint/drops may be needed ▫ Keep eyes clean and clear • Prevent eye issues – riding out car window! Epiphora • Overflow of tears ▫ Overproduction (pain or irritation) ▫ Faulty drainage: (lacrimal duct blocked by swelling or trauma) • Clinical Signs ▫ ▫ ▫ ▫ Watering of the eye Wet facial hair Secondary bacterial infection of facial skin Discoloration of the facial hair Epiphora cont’d……. • Dx: ▫ Eye exam ▫ Fluorescein dye ▫ Dacryocystorhinography ( Radiography of nasolacrimal duct ) • Tx: Resolve primary cause of pain & irritation / Flush lacrimal ducts / Surgery / Topical abx/ Trim hairs Eyelid Diseases • At the base of each eyelash is a sebaceous gland Hordeolum: Meibomian gland abscess, usually caused by a staph. infection Chalazion: When inflammation involves meibomian glands & granulation occurs • Eyelid neoplasms : Older animals/ most are benign (cat usually malignant), Squamous cell carcinoma most common tumor Blepharitis: Swelling of the eyelids • Causes: ▫ ▫ ▫ ▫ Allergens Nutritional Deficiencies Viral Dermatitis from any cause • Clinical signs ▫ ▫ ▫ ▫ Generalized swelling of lid Periocular pruritis (itchy eyes) Periocular alopecia ( hairloss) Rubbing of the eyes Blepharitis Cont. • Dx: ▫ ▫ ▫ ▫ Eye exam Skin scrape Fungal culture Bacterial cultures • Tx: warm compresses ▫ Express hordeolum(staph infection) ▫ Surg. removal of chalazion (granulation tissue) ▫ Topical abx or systemic abx ▫ Corticosteroids ( Prednisolone) ▫ Antifungals ( Conofite or Tresaderm) Blepharitis Entropion • Eyelids roll in against the cornea • Common in dogs, not in cats • 3 main forms: ▫ Congenital: breeds have large orbits with deep-set eyes, inadequate lid support, lid droops over the lower orbital rim and inverts – Collies, Great Danes, Irish Setters, Dobes, Goldens, Rotts, Weim (primary lid deformities, poor ocular muscle development) ▫ Acquired nonspastic: surgical or traumatic – scarring of the lid with contraction – lid turns inward ▫ Acquired spastic – most common in cats – secondary to painful corneal lesions, conj. inflam. or both Entropion Entropion • Clinical Signs ▫ ▫ ▫ ▫ ▫ ▫ ▫ ▫ ▫ Rolling inward of the lid margin(s) Epiphora (tear overflow) Chemosis ( conjunctiva swelling ) Swelling Conjunctivitis Blepharospasm(eyelid muscle spasm) Pain +/- corneal ulceration Photophobia Entropion Con’t…… • Dx: ▫ Observe lids interaction with globe ▫ Eye exam while awake • Tx: Surgical correction Ectropion: Eyelids that roll outward, exposing the cornea • Excessive lid droops outward • Natural breed characteristic for: Basset hounds, bloodhounds, cocker span, clumber span, Eng. bulldogs, St. Bernards – usually asymptomatic • All breeds: Secondary to muscular dz in senile dogs/ Dogs w/ surgical overcorrection of entropion • Clinical signs ▫ ▫ ▫ ▫ ▫ Lid eversion Conjunctivitis Epiphora Keratitis Purulent exudate Ectropion Cont. • Dx: ▫ Observe lids ▫ Interaction with globe ▫ Eye exam while awake • Tx: Surgical correction advised if clinical signs present “Cherry Eye” or Hypertrophy of Nictitans Gland • Third eyelid: ▫ Protective structure/Spreads pre-corneal tear film Covers eye to protect from injury/ Produces ~50% of lacrimal fluid • Prolapse of 3rd eyelid/gland: “passive forward displacement when eye withdrawn into orbit” Hypertrophy of gland ONLY occurs in K9’s • Etiology: Unknown cause • Breeds: Basset, beagle, Boston, cocker Cherry Eye • Usually seen in young dogs (< 2 yrs. old) -usually neoplasia if seen in old K9’s & cats • Medial canthus is filled with red, swollen, third eyelid, resembles a small cherry • Clinical signs ▫ Reddened enlargement of tissue in the medial canthus of the eye ▫ Mild irritation ▫ Usually no pain ▫ Epiphora ( tears) ▫ +/- conj. irritation Cherry Eye continued….. • Dx: ▫ Clinical signs ▫ Predisposed breed ▫ Rule out tumor (usually older dogs & cats) • Tx: ▫ Surgical replacement of the gland, Tuck sutured ▫ Avoid excision – predisposes to KCS – only excise in cases of neoplasia • W/O sx., corneal damage can occur & may affect vision Cherry Eye Glaucoma: • In healthy eye: Aqueous fluid production =‘s aq. fluid amt. leaving eye, so IOP(intraocular pressure) remains fairly constant • More aqueous fluid produced than leaves = glaucoma • Normal k9/fel IOP range: 12-22 mm Hg w/ Tono-pen • Most K9’s have decreased outflow, not increased prod. • Primary – inherited defect (cocker, basset, chow) • Secondary –drainage angle obstruction secondary to another dz.– ie: Neoplasia, uveitis, lens luxation, hemorrhage Glaucoma cont’d • Acute – elevated IOP (> 60 mm Hg ) can produce blindness within hours Clin. signs: Ocular pain, vascular congestion, diffuse corneal edema, dilated pupil, sluggish or unresp to light, +/- blind • Chronic – painful, blind eye which is unresponsive to med. therapy. Make pet comfy w/salvage procedures Clin. Signs: Enlarged lobe, corneal striae, optic disk cupping, pain, blindness • Dx: IOP > 30 mm Hg,/ clin. signs/ r/o luxated lens • Tx: Acute – true emergency – decrease IOP rapidly, sx Chronic – sx – enucleation • Bilateral disease – even if one eye is asymptomatic Corneal Ulcers Ulcerative Keratitis • Cornea:Window of the eye- has 4 layers ▫ ▫ ▫ ▫ Epithelium Stroma Descemet’s membrane Endothelium • Full-thickness loss of corneal epithelium exposing stroma • Etiology: Trauma, chemicals, foreign body, prev. dz. ie: KCS/ Herpes in cats, conformation issues, distichiasis (tiny, inwardly –facing meibomian gland hairs) • Clinical signs ▫ Pain ▫ Epiphora ▫ Blepharospasm ▫ Conjunctival hyperemia Corneal Ulcers • Dx: ▫ Fluorescein dye- absorbed by stroma, not by epithelium (green uptake of dye) WARN client about fluorescent green dye !! • Tx: ▫ Topical Atropine ▫ Topical abx ▫ Sx • Meds. w/ cortisone slow healing & makes condition worse • Frequent re-evaluations needed to monitor progress/healing Pannus: Chronic Superficial Keratitis • Superficial corneal vascularization & infiltration of granulation tissue (lymphocytes & plasma cells) • Progressive, bilateral, degenerative, can result in blindness • Cause – immune-mediated, animals at > 5000 ft most susceptible (G.shep, B. Terv, B. Collie, Greyh, SibHusky) • C/S: breed predisposed with opaque lesion – pink or tan • Dx: corneal scraping – infiltrate, eye exam • Tx: Antiinflam. for life of patient, +/- subconj. inj., cryosurgery, superficial keratectomy • No cure Treatment to maintain regression of lesion is life-long Pannus “KCS”: Keratoconjunctivitis Sicca • Loss of both lacrimal glands • Viral inf., drug-related toxicities, Imm-mediated dz, inflamm, breed predisp., congenital abn • Most cases idiopathic, older >7 yr. – neutered • Clinical signs ▫ ▫ ▫ ▫ ▫ ▫ ▫ Recurrent conjunctivitis Corneal ulcers Keratitis Cornea & conj. appear dull, dry, & irregular Ocular discharge Blepharospasm Crusty nares KCS cont’d ….. • Dx: ▫ Schirmer Tear Test <15mm/min on repeat testing (k9 1525, fel 11-23) NOTE: Perform this test 1st ▫ 2nd: Fluorescein dye –assess ulcer presence • Tx: ▫ Stimulate tear prod. w/meds (cyclosporine) ▫ Topical art. tears ▫ Surgery if medical tx are unsuccessful (parotid duct transposition) • Failure to treat will result in blindness Cataracts : • Most common dz. involving the lens • An opacity of the lens sufficient enough to cause a reduction in visual function – aging cells w/in lens become dehydrated & overlap each other, producing a central change in the reflection of light- lens may appear grey and opaque • Freq. cause of blindness in dog, occas. seen in cat • Etiology: Inherited, secondary to diabetes mel., hypocalcemia, trauma, nutritional deficiency, electric shock, uveitis, or lens luxation (Photo Credits: dog-health-handbook.com ) Cataracts cont’d • Clinical signs ▫ Progressive loss of vision ▫ Opaque pupillary opening ▫ Signs related to systemic dz. (diabetes mellitus or hypocalcemia) • Dx: ▫ Complete eye exam/Assess via obstacle course/ Lack of menace /Failure to track visual responses Photo Credits: petdig.com Cataracts cont’d…….. • Pupillary light response is usually normal • Tx: ▫ Sx removal ▫ Tx of any other dz Anterior Uveitis • Inflammation of the uvea (iris, ciliary body, choriod) • Trauma, extension of local infx, foreign body, neoplasm, thermal trauma, parasites, protozoa (bact, viral, mycotic dz – hematogenous spread) • C/S: epiphora, photophobia, blepharospasm, +/vision defects, corneal edema, chemosis, prolapsed 3rd eyelid, pain, change in iris color • Dx: c/s, hx, labs, x-ray, ultrasound, tonometry • Tx: I.D. & elim. cause, control inflamm w/topical steroids (w/o tx, vision will eventually be lost) Progressive Retinal Atrophy • Group of hereditary retinal disorders seen in many breeds of dogs (can occur in cats, but not as frequently) • Toy poodles, min poodles, goldens, Irish sett, cockers, min sch, collies, samoyed, gordon sett, Norw. Elkhound • C/S: defective night vision, slowly progressive loss of day vision, cataract formation • Dx: labs, eye exam of retina • No Tx. currently exists Horses • Entropion • Conjunctivitis – Summer/ dry, dusty condition /flies • Corneal ulcers • Cataracts – Sx. prognosis is good in foals • Many blind horses can still be ridden safely, if owner doesn’t exceed horse’s ability & comfort level … (or the owner’s !) “Moon Blindness” Periodic Opthalmia, Recurrent Uveitis • Comes & goes/ exact cause undetermined • Many animals have high Lepto antibody titer • Signs: cloudy eye, blepharospasm, excessive tears • Dx: visualization of protein flare in fluid of anterior chamber, affected eye may be smaller, corneal stain, Lepto titer • Tx: topical corticosteroids, atropine, banamine or Subconjunctival long-acting steroid injections Sheep and Goats • Entropion – most common ocular abnormality in neonatal lambs • Infectious Conjunctivitis (Pinkeye) – responds well to medication – herd management • Cataracts – most common lens abnormality in sheep and goats