Diseases of the Eye

1. Diseases of the Eye Casey Conway Jeannie Stall , R.V.T. & ??? Credits : Clip Art graphics/Google images

2. 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

3. Anatomy Credits: ukvetsonline

4. 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

5. 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

6. 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!

7. 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

8. 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

9. 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

10. 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

11. 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)

12. Blepharitis

13. 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

14. Entropion

15. 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

16. Entropion Con’t…… • Dx: • Observe lids interaction with globe • Eye exam while awake • Tx: Surgical correction

17. 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

18. Ectropion Cont. • Dx: • Observe lids • Interaction with globe • Eye exam while awake • Tx: Surgical correction advised if clinical signs present

19. “Cherry Eye” orHypertrophy 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

20. 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

21. 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

22. Cherry Eye

23. 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

24. 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

25. Corneal UlcersUlcerative 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

26. 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

27. 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

28. Pannus

29. “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

30. KCS cont’d ….. • Dx: • Schirmer Tear Test <15mm/min on repeat testing (k9 15-25, 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

31. 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 )

32. 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

33. Cataracts cont’d…….. • Pupillary light response is usually normal • Tx: • Sx removal • Tx of any other dz

34. 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)

35. 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

36. 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 !)

37. “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

38. 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