Ophthalmic Disease

  1. What do dogs and cats see?
    • Dogs can't distinguish the full spectrum of colors
    • Retina has more rods, humans have more cone cells
    • Dogs appear to be better than people with peripheral vision
    • their close-up vision does not seem as sharp as a human's
  2. Canine eye registry foundation(CERF)-
    • collects and disseminates information about breed-specific eye disease
    • Aims to reduce genetically transmitted ocular conditions
    • Breeders of at risk breeds should have parents and puppies evaluated by veterinary
    • ophthalmologists who submit data to CERF
  3. Anatomy of the eye
    • Cornea-clear window at the front of the eye
    • Third eyelid and gland-the third eyelid is raised protectively and has a tear gland
    • Iris- colored part of the eye that constricts with light
    • Lens- focuses light onto the back of the eye (on retina)
    • Retina- rods, cones and nerve layer of the eye that converts light into an signal that is
    • transmitted to the brain for vision
    • Tapetum-reflective; area that reflects light through  retina; "eye-shine" at night
    • Non-tapetum-the pigmented area of the retina
    • Choroid- blood vessels that supply nutrients to the eye and reflective cells that give the tapetum color
    • Optic nerve- carries visual information to the brain
    • Anterior and posterior chambers
  4. Diagnostic Materials
    • topical anesthetic-temporarily eliminates pain associated with the  and ocular disease to allow thorough examination of eye
    • The Shirmer Tear Test-measures tear flow in the eye 
    • Fluorets-paper strips that contain the
    • stain that demonstrates the corneal defect 
    • ophthalmoscope-is used to highlight the cornea and to allow examination of internal structures of the eye 
    • Tonometer-evaluates intraocular pressure
  5. Conjunctivitis
    Inflammation of the inner lining of the eyelids
  6. Clinical signs: Conjunctivitis
    • persistent squinting
    • excessive blinking
    • redness of the eye tissue
    • ocular discharge
    • rubbing the eyes
  7. Conjunctivitis Diagnosis
    and Treatment
    • PE
    •  Fluoroscein strip to rule out ulcer
    • Schirmer tear test
    •  Topical antibiotics AND topical steriods
  8. The Cornea-3 important functions:
    • a supportive barrier to keep the internal structures in place within the eye
    • allows light to pass into the eye and thus through the
    • lens to the retina at the back of the eye
    • bends the incoming light rays to aid the lens in focusing the incoming light
    • Composed of 5 microscopically identifiable layers-deep or superficial ulcers(deep more painful and worse prognosis)
  9. Corneal ulcers-Causes
    • Injury
    • bacterial, fungal, and viral(feline herpesvirus )infection
    • diseases of the eye and eyelid
    • Boxer breed appears to have a genetic predisposition to spontaneous corneal
    • ulceration
    • can develop serious complications that may compromise visual acuity or result in loss of sight if not promptly treated
    • All ulcers are painful !
    • Rough contact with plants, thorns, or
    • bushes- hunting dogs, outdoor cats
    • Scratches from another animal
    • Trauma
    • rubbing or scratching at a painful ear or even at the eye due to some other eye
    • problem-allergy dogs
    • Chemical irritation (shampoo)
    • Foreign body injury
    • plant material can get stuck under an eyelid and can scrape the cornea
  10. Clinical signs-Corneal ulcers
    blepharospasm, epiphora, purulent ocular discharge, and photophobia,pain, squinting or blinking the affected eye, pawing or rubbing at eye, excessive tearing or discharge, pus, redness, behavioral changes(hiding or avoiding light)
  11. Superficial corneal ulcers
    • Superficial scratches of the outer layer of the cornea(epithelium)
    • do not penetrate deep
    • usually heal without treatment in two to three days
    • The denuded epithelium in corneal ulcers heals by epithelization
    • intact epithelial cells move to the defect and undergo mitosis, or simple cell division, and the new cells close the crater in the epithelial layer
    • normally takes seven to 10 days
    • However, all corneal ulcers are susceptible to bacterial infection, which will delay healing(scars!)
  12. Deep corneal ulcers
    • take a number of weeks to heal
    • require aggressive treatment
    • During healing, blood vessels from the outer rim of the cornea may grow on the floor
    • of the ulcer, a process called neovascularization
    • promotes deep healing by providing extra nutrients to the damaged area
    • scar tissue will form-blood vessels can regress and scar tissue will be remodeled but residual scar tissue and vessels common
  13. Diagnosis:Corneal ulcers
    • fluorescein stain and exam
    • Chart size & depth & location
  14. Corneal Ulcers-Treatment
    • Goals of treatment:
    • treating or preventing infection
    •  controlling pain(spasms) and inflammation
    •  preventing further corneal damage
    • minimizing the disruption of the clear cornea by limiting scar formation
    • Superficial ulcers:
    • topical antibiotic ointment
    • atropine(control painful spasms and dilate the pupil to prevent iris-corneal adhesions)
    • Light sensitive
    • Deep: aggressive medical therapy, surgical grafts, debridement, etc…
    • Frequent reevaluation with fluorescein drops to monitor healing
    • E collars!
    • Self trauma a problem
    • NO STERIODS used during treatment of corneal ulcers!
  15. Special Ulcers-Indolent Ulcers
    • The majority of corneal ulcers will heal rapidly within a few days
    • the epithelium regenerates from the edges of the ulcer and spreads across the defect
    • in some dogs this does not occur and they develop an ‘indolent’ corneal ulcer
    • This type of corneal ulcer is shallow and non-infected but refuses to heal
    • Why does an indolent ulcer refuse to heal?
    • The epithelium at the edge of the ulcer is loose and underrun, unable to ‘stick down’ and heal the defect
    • For healing to occur, this non-adherent epithelium needs to be removed so that normal healthy epithelium can form and spread across to allow healing
    • surgical correction with debridement, grid keratectomy
    • Poodles,boxers
  16. Special ulcers Desemetocoele
    • an ulcer that has penetrated through the cornea completely except for the last thin membrane
    • eye with a descemetocoele is high risk for rupture
    •  Usually surgery is needed 
    • The brachycephalic breeds (Pekingese, pug etc) are very predisposed due to their
    • prominent eyes
    • Treatment with conjunctival graft
  17. Dry eye/ kerato-conjunctivitis sicca/KCS
    • a deficiency in the watery portion of tears
    • A dry eye is more prone to bacterial infections, conjunctivitis, and
    • corneal ulcers
    •  chronic kcs
    • eyes develop corneal scarring and pigmentation(obstruction of vision)
    •  most cases are inherited or due to unknown causes
    • usually bilateral
    • chronic
    • requires management for the duration of the dog's life to prevent discomfort and loss of
    • vision associated with scarring of the surface of the eye
    • Chronic pigmentary keratitis and corneal edema secondary to Keratoconjunctivitis Sicca
  18. KCS Clinical signs:
    • thick, mucous yellow-green eye discharge
    • Ulcers
    • scarring and pigment deposition can occur over time
  19. causes of KCS:
    • Autoimmune 
    • Congenital – Some dogs are born with
    • defective tear glands
    • Trauma – Damage or inflammation of the
    • tear gland or of its nerve supply
    • Drug Reaction – Certain drugs can cause KCS, including sulphonamide antibiotics
    • Viral Infections – e.g. Canine Distemper, Feline Herpesvirus
    • Hormone Imbalance – e.g. Hypothyroidism (underactive thyroid gland)
    • Idiopathic
  20. KCS-diagnosis
    • clinical signs, Schirmer tear test- small strip of paper is placed in the conjunctival sac for 60 seconds;amount of tears wicked up by the paper in one minute is measured
    • A normal result for a Schirmer Tear Test
    • 15-25mm/min in dogs
    • 7-12mm/min in cats
  21. Treatment: KCS
    • medical
    • There are two types of long term medical treatment for KCS:
    • artificial tears
    • drugs which are used to stimulate tear production
    • most animals respond well to medical therapy
    • Also- antibiotics, anti-inflammatories
    • Surgical-parotid duct transposition
  22. Nictitans Gland Prolapse
    • The nictitating membrane(3rd eyelid)
    • helps cleanse and lubricate the eye- about 30% of tear production
    • Cause unknown-
    • a weakness of the ligament that holds the gland in place
    • Out of its normal position, the gland does not circulate blood properly and may swell
    • "Cherry eye” usually occurs in young animals
    • and can affect both eyes
    • Breeds: American Cocker Spaniel, English Bulldog, Lhasa Apso, Boxer
  23. Treatment NIctitans Gland Prolapse
    • surgical correction-do not remove the 3rd eyelid
    • medical therapy as well
    • Prognosis good
  24. Entropion
    • a congenital defect common in dogs with deeply wrinkled facial features
    • Inward rolling in of eyelids-us. top
    • eyelashes rub against the cornea constantly
  25. Entropion Clinical signs:
    • Redness and pain around the eye
    • Sensitivity to light and wind
    • Excessive tearing, ocular discharge
    • Decreased vision, especially if the cornea is damaged
    • Bloodhound, Bulldog, Retrievers, Chow Chow, Rottweiler, and Shar Pei are prone to entropion, although any breed may be affected
  26. Treatment: Entropion
    • “Blepharoplasty”- “removing a small portion of the skin to tighten the eyelid
    • ”eye-tack” and Symptomatic medical
    • therapy
    • Dogs with inherited entropion should not be bred
    • Canine Eye Registration Foundation (CERF) publishes a list of breed-specific breeding recommendations for purebred dogs with entropion
  27. Glaucoma
    • Increased IOP
    • Cells in the eye produce a clear fluid (AH)that nourishes the eye and
    • maintains eye shape
    • Aqueous humor made in the ciliary body flows through the pupil into the
    • anterior chamber
    • Aqueous then drains into the bloodstream through the iridocorneal angle
    • Fluid production and drainage are
    • balanced to maintain intraocular pressure
    • the drainage is blocked and the eye stretches and is enlarged, leading to blindness
    • Excess fluid is produced
    • normal intraocular pressure- between 10 mmHg and 20 mmHg in most animals
    •  Pressures that exceed 20mmHg are of concern
    • Depending on breed…
    • above 30 mmHg start to cause irreversible damage to the internal structures of the eye
  28. two main types of glaucoma:
    • primary
    • due to decreased outflow from the drainage angle
    • It is frequently an inherited problem.
    • Beagles, Basset Hounds, and Cocker Spaniels are especially prone to this type of glaucoma.
    • secondary
    • something else is wrong in the eye, such as a lens luxation, bleeding, inflammation, cataracts or tumor causing increased IOP
  29. Causes of glaucoma
    • a problem with the drainage angle
    • (narrow-angle glaucoma or goniodysgenesis) and is often an inherited disease
    • Eventually both eyes
    •  Breeds:Basset Hounds, Beagles, Boston
    • Terriers, Cocker Spaniels and Shar-Peis
    • an obvious cause such as trauma, inflammation, intraocular bleeding, lens luxation or a tumor
    • Usually one eye is affected
    • If the cause can be eliminated then the glaucoma may be easier to control and can often be eliminated
  30. Signs of Glaucoma
    • 1. A red (bloodshot) eye
    • 2. A painful eye
    • 3. Lids may be held shut
    • 4. Excessive tearing
    • 5. Eye may appear cloudy or blue
    • 6. Sudden blindness
    • 7. A dilated (enlarged) pupil that does not respond normally to light
    • 8. Depression
    • 9. Appetite loss
    • 10. Enlargement of the eye
  31. How does glaucoma affect the eye?
    • Vision Loss
    •  Pressure damage to the optic nerve and
    • decreased blood flow to the retina
    • if the pressure in the eye remains uncontrolled, the retina degenerates and vision is permanently lost
    • Permanent blindness can occur within
    • several hours if the pressure is very high and the glaucoma develops rapidly!
    • PAIN
    • Glaucoma often results in pressures of 20-28 mmHg in humans, but pressures of 45-65 mmHg are common in dogs and cats!
    • glaucoma in pets may be more painful than glaucoma in humans
    • a constant headache or migraine
    • results in decreased activity, less desire to play, irritability,decreased appetite
    •  often not apparent to the owner
    • Our pets can’t talk!!
  32. Glaucoma Clinical signs:
    • an acutely red, painful eye with corneal cloudiness, excessive tearing,
    • eyeball swelling, pain, and sensitivity to light
    •  Rapid vision loss
  33. Feline glaucoma
    • (Vet Ophth :4(2):81-85, June 2001)
    • rarely seen as a primary disease
    • usually is secondary to chronic anterior uveitis, occasionally secondary to intraocular neoplasia (iris melanoma or lymphosarcoma)
    • seen in older (9+ years) cats as insidious buphthalmos, mydriasis, vision loss
    • Rarely appears to be painful with an "acute" attack as is the usual case with glaucoma in dogs
  34. Glaucoma diagnosis
    • exam: may present unilaterally but both eyes are at risk
    • IOP >25mmHg
    • Conjunctival hyperemia
    • Diffuse corneal edema
    • Fixed, relatively dilated pupil
    • Signs of general malaise(lethargy, anorexia)
  35. Glaucoma treatment
    • Medical therapy alone does not work well long term; used to delay affects of glaucoma in the visual eye or treat eye prior to surgery
    • If dog has lost one eye to Primary Glaucoma the other eye is at risk of developing glaucoma
    • The median time until an attack occurs in the other eye is 8 months
    • Prophylactic medical therapy for the remaining eye delays the onset of glaucoma from a median of 8 months to a median of 31 months
    •  Cycloablation Surgery and Drainage Implant
    • Surgery FOLLOWED BY Lifetime Medical Therapy:
    • Cells in the eye that produce fluid are killed surgically To help control pressure for the first few weeks after surgery, a drainage tube is sometimes implanted into the eye
    • 30% of dogs will require additional surgeries
    • (Electroretinogram first)
    • Glaucoma treatment-visual eyes
    • Lifetime Medical Therapy Alone
    • Oral and topical medication to control intraocular fluid production and increase fluid drainage
    • eye drops- xalatan, timololor trusopt help decrease fluid production or pressure within the eye
    • orally administered tablets-diuretic acetazolamide or methazolamide-help decrease fluid production in the eye
    • Enucleation: Removal of the eye, and the eyelids are sutured closed
    • Enucleation and Orbital Prosthesis (not recommended for cats)
    • Removal of the eye
    • A black prosthetic ball is then placed in the orbit and the eyelids permanently closed
    • Prevents "sunken-in" appearance of skin
    •  Evisceration and Intrascleral Prosthesis: inside of eye removed and replaced with a prosthesis
  36. Glaucoma prevention
    The key to having the best chance of preserving vision is early detection and regular ophthalmic examinations
  37. Feline uveitis
    • Compared to dogs, cats don't get many eye diseases one of the most common eye problems in cats is uveitis-usually chronic and can cause blindness and ocular pain
    • Uveitis is inflammation of the uveal tract, which is the pigmented, vascular part of the
    • eye
  38. Uvea
    the "blood-eye barrier"
    • Uvea
    • the vascular portions of the eye:
    • iris, cilary body, and choriod the ciliary body makes the aqueous humor, and the choroid nourishes the outer retinal layers (rods and cones and bipolar cells)
    • the "blood-eye barrier"
    • prevents blood components (albumin and other proteins, RBC's and WBC's) from getting into the aqueous humor and between the retinal pigment epithelium and the neuroretina
    • "breakdown" of the "blood-eye barrier“ by inflamm. cells
    • large protein molecules
    • ("plasmoid aqueous" or "aqueous flare"), RBC's (hyphema), and WBC's (hypopyon) may appear in the aqeuous humor and vitreous or in the subretinal space (seen as subretinal exudate or detachment of the retina)
    • the "stability" of this "blood-eye barrier" varies with the species
    • From "toughest" to "weakest" is as follows: primates (man), ruminants, cats, dogs, horses, rabbits
  39. Clinical signs-uveitis
    • squinting, sensitivity to light, third eyelid protrusion, tearing, redness to the white part of the eye, abnormal pupil shape or size, an altered iris color (usually a "muddy" or reddened color compared to the normal color), cloudiness, cataract
    • Etiology: 60% of cases unknown
    • trauma, an infectious disease, or cancer(toxo, bartonella, feline herpesvirus, FeLV, FIP)
  40. Treatment of uveitis
    • Depends on cause
    • Always check for glaucoma!
    • Requires lifelong management-difficult to control
  41. Cataracts
    • A cataract is an opacity of the lens
    • Classified as:
    • congenital(present at birth) or inherited
    •  juvenile or senile(age 6yr and older)
    •  Large cataracts can reduce lens functions to
    • the point of blindness, but surgical removal of cataractous lenses can restore
    • sight
    • must check the retina to see if it is functional before deciding whether to surgically remove
    • a cataract
    • Signs of vision loss are usually not detected by the owner until the cataract occupies
    • 40-50% of the lens.
  42. What is not a cataract?
    • All geriatric dogs develop a hardening of the lens (Nuclear Sclerosis) that causes the lens
    • to have a greyish appearance
    • This is not a cataract, and does not usually interfere with vision
  43. Nuclear sclerosis

    • Nuclear Sclerosis is a normal aging change of the lens
    • The lens is made up of several layers of cells (like the layers of an onion)
    • Layers of cells are added continually throughout the animal's life.
    • As animals age new layers are added and the cells become packed together more tightly in the center of the lens (the nucleus)
    • The increased density of the lens causes it to look more cloudy in dogs over seven years of age
    • The lens will become increasingly cloudy as the animal ages, but it almost never has an effect on vision
  44. What Causes Cataracts?
    • Heritability/ Genetics: one of the most common causes of cataracts in dogs. 
    •  CERF exams (Canine Eye Registration
    • Foundation) detect cataracts suspected or proven to be of heritable cause
    • Breeds: Cocker spaniels, boston terriers, miniature schnauzers, labs, west highland white terriers, standard poodles, german shepards, siberian husky, labrador retrievers, golden retrievers
    •  Metabolic:
    • Diabetes mellitus is the most common cause of metabolic cataracts(abnormal metabolism of glucose by the lens)
    •   These cataracts are always bilateral, and form rapidly
    •  Hypocalemia resulting from renal failure or hypoparathyroidism can cause cataracts in dogs(multifocal and bilaterally symmetric)
    •  Secondary to Uveitis: chronic iridiocyclitis can induce cataract formation by altering lens nutrition or microenvironment
    •  Senile: old age frequently causes catacts
    •  Secondary to retinal disease: progressive (PRA) is common in Poodles , Labs, Irish
    • Setters.  Check history for evidence of blindness or poor dim light vision before cataracts developed.
  45. Cataract treatment
    • cataracts cause a serious reactive inflammation inside the eye (Lens Induced Uveitis, or LIU) that must be medically treated, whether or not surgery is performed
    • Anti-inflammatory drops and periodic eye exams
    • Surgery performed under high magnification using an operating microscope.
    • (electro-retinogram test may be necessary to evaluate the function of the retina)
    • Phacofragmentation / Phacoemulsification:
    • ultrasound is used to fragment the cataract, which is then aspirated from the eye through a 3mm incision; IOL can increase animal’s focusing ability
    • Post op monitoring
  46. PRA-Progressive Retinal Atrophy
    • an inherited disease of the retina (tissue layer at the back of the eye containing the rods and cones)
    • retina slowly degenerates with time
    • Owners usually notice loss of night vision first, progresses to total blindness
    • Dogs 6-8 yrs
    • forms:
    •  dysplasia (developmental abnormality of
    • the photoreceptors - typically a very early onset of clinical signs prior to one year of age)
    • degeneration (a later onset condition occurring after normal maturation of the photoreceptors)
    • Ophthalmic exam- thinning of retina and decreased size of retinal vessels
    • PRA produces a slow blindness that allows time for dogs to adjust(except for acute form/sards)
    • Rely on their heightened senses of smell, hearing
    • Painless
    • No treatment
    • There are DNA blood tests available, to
    • determine if dogs are likely affected with PRA, are likely carriers for PRA, or are not likely carrying the PRA gene
    • Akita, Alaskan Malamute, Beagle, Border Collie, Borzoi, Chesapeake Bay Retriever, Chow Chow,Cocker Spaniel, Collie,Laborador Retreivers, Poodles, Shih tzu, Rottweiler, Lhasa apso, Miniature schnauzer, Golden retreiver
  47. Can blind pets lead happy lives?
    • The answer is an unequivocal "YES!“
    • Rely on other heightened senses
    • Degree of handicap cannot be compared to humans
    • Protect their environment(pool)
    • Will still play, interact with family members
    • Books, websites offer support
    • blind dogs and cats can live as happy pets if one follows a few simple guidelines to make life easier for them
    • Animal's senses of hearing and smell are so much better than ours that when an animal is in a familiar environment it is often hard to tell that it is blind
    • Avoid changing your pet's environment
    • But, if you do move furniture or move into a new house, you may find it takes several weeks for your pet to memorize and familiarize itself with the new surroundings.
  49. Guidelines for caring for a blind dog
    • Encourage them to use their other senses to compensate for vision loss
    •    a. Buy toys that are noisy (that have a ring or a rattle) or ones that have a recognizable
    • odor.
    •    b. Apply perfume on legs of furniture or the edges of stairs to help them know where
    • these objects are located.
    •    c. Get another companion animal that your blind pet can follow around, using its senses of hearing and smell observe  eyes daily for changes that could indicate the onset of glaucoma or uveitis (inflammation), conditions which can be very painful!
    • 2. Teach your pet to walk on a harness or lead so that it can be exercised safely
    • Start using more voice commands to help he or she know when to slow down or be careful
    • 3. Fence in a small area of yard for them and keep the environment constant
    • 4. fence in the pool
    • 5. Encourage them to use their other senses to compensate for vision loss.
    • 7. Encourage exercise, whether in a fenced yard or on a leash, to prevent excessive weight gain
    • 8. Do not change the placement of the bowls of food and water,
    • 9. Some behavior changes (aggression, depression, fear, etc.) can be observed
    • with sudden blindness. Try to avoid stressing or scaring the pet. Inform the
    • family members (especially children) of the new condition and educate them to alert the pet with soothing words or sounds before petting or grabbing the
    • animal
Card Set
Ophthalmic Disease
Ophthalmic Diseases in small animals