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What area the three main categories of ophthalmic problems?
- accessory structures
- structures of the globe
- retinal and neural pathway
What are the accessory structures?
- tear ducts
- nictitating membrane
- lacrimal glands
What is conjunctivitis?
inflammation of the conjunctiva
Is conjunctivitis a primary disease?
Is the conjunctiva highly vascular?
What is hyerpemia?
redness of the eyes
What is chemosis?
swelling of the eyes
What are the different causes of conjunctivitis in cats?
- Chelmydia felis
- Mycoplasma felis
- Bacillus spp
- Staphylococcus spp
- Feline herpes virus 1
- Calici virus
- irritant conditions
- accomplany other ocular disease
What are the different causes of conjunctivitis in dogs?
- canine distemper virus
- immune mediated, atopy, pannus
- irritant conditions
- accompany other ocular disease
What are the clinical signs of conjunctivitis?
- ocular discharge - serous or mucopurulent
- swelling of conjunctival lymph follicals (cobblestone)
What is epiphora?
overflow of tears
How do you diagnose conjuncitivis?
- complete physical exam
- thorough visual exam of conjunctiva
- conjunctival scraping, cytology, culture and sensitivity
- Schirmer tear test
- fluorescein stain
- intraocular pressure
- check lid for entropion, ectropion, trichiasis, distichiasis, ectopic cilia, foreign body
- check behind the third eyelid
- cornea - keratitis, ulcer
- intraocular inflammation
What is entropion?
eyelids rolled inward toward cornea
What is ectropion?
eyelids rolled outwards away from cornea
What is trichiasis?
normal hairs that touch the cornea or conjunctiva
What is distichiasis?
hairs from the meibomian glands on the inner lid surface
What is ectopic cilia?
hair growing from an abnormal place
How do we treat conjuncitivits?
- treat underlying systemic disease if any
- treat primary ocular disease
- topical antibiotic ointments
What are some different topical antibiotic ointments we can use?
- polymyxin B
- Gentamicin ointment
- may contain corticsone for follicular or atopic conjunctivitis
- nonsteroidals - Ketorolac, Lodoxamide
How do we treat viral conjunctivitis in cats?
- idoxuridine (IDU)
- adenine arabinoside (Vir-A)
- lysine PO - arginine inhibitor - slows replication of herpes virus
- keep eyes clear of discharge
What kind of client education do we need to provide about conjuncitivis?
- do not allow your dog to ride with his head out the car window
- remove excess hair that may trap discharge
- vaccinate kittens for upper respiratory disease
- do not touch ointment tip to the eye
- ointments provide longer contact time than solutions
- need to be applied frequently to be effective
- demonstrate proper technique of applying medications
What is epiphora?
overflow of tears
What causes epiphora?
- overproduction o ftears due to ocular pain or ocular irritation
- faulty drainage - lacrimal system
What causes faulty drainage in the eye?
- blockage of ducts by swelling or inflammation
- imperforate puncta, trauma
Why do brachycephalics have a problem with epiphora?
- large globes, shallow orbits
- little room for accumulation of tears - tears spill out on face
- accumulation in hair or face folds may wick the tears onto face
What are the clinical signs of epiphora?
- watering of the eye, acute or chronic
- wet facial hair in medial canthus
- secondary bacterial infection of periocular skin
- discoloration of periocular skin and hair
How do we diagnose epiphora?
- eye exam - look for causes of pain
- fluorescein stain - look for stain to exit through the nares
How do we treat epiphora?
- treat primary cause of pain or irritation
- flush nasolacrimal ducts to remove obstructions
- surgically open imperforate puncta
- surgical correction of lids
- keep facial hair trimmed away from eyes to prevent contact with cornea
What is keratoconjunctivitis sicca (KCS)?
- dry eye
- deficiency of aqueous tear production
What are the purpose of tears?
- reduce bacteria
- aid in healing
What are the three tear layers?
What is the the aqueous layer?
- produced by lacrimal gland
- bulk of tear volume
- immunoglobulins, enzymes, glucose, proteins, ions, salt
What is the lipid layer?
- secreted by the meibomian glands
- aids in tear distribution
- waxy - helps hold watery tears in the orbit
What is the mucus layer?
- secreted by conjunctival goblet cells
- aids in tear adherence to the corneal surface
How many lacrimal glands do dogs and cats have? What are they?
- lateral orbit
- nictitans gland
What does the lateral orbit lacrimal gland do?
produces 70% of tear volume
What does the nictitans gland do?
produces 30% of tear volume
What does the loss of both lacrimal glands produce?
What are the clinical signs of KCS?
- recurrent conjunctivitis, corneal ulcers, and keratitis
- cornea and conjunctiva appear dry, dull, and irregular
- tenacious mucoid ocular discharge (mucopurulent)
- discharge sticks to cornea and lid margins, conjunctival sacs
- crusty nares
- corneal vascularization
- corneal pigmentation
- decreased vision
- usually bilateral, may be unilateral
How do we diagnose KCS?
- schirmer tear test (STT)
- base diagnosis on clinical signs and STT together
What is the Schirmer Tear Test?
- commercially available test strips
- absorbable strips
- use same brand each time animal is rechecked
- remove excess corneal discharge
How do you do the Schirmer Tear Test?
- bend test strip at notch
- place bent area into the conjunctival sac
- close lids and leave in for one minute
- measure tears on the strips in mm
Should we use other medications and eye drops before doing the STT?
How do we treat KCS?
- tear stimulation
- artifical tears
- topical antibiotic ointment
- parotid duct transposition
How do we do tear stimulation?
- cyclosporines (Optimmune)
- cyclosporines in corn oil - can get compounded at most pharmacies
- oral pilocarpine in food (salivation, vomiting, diarrhea, and bradycardia)
What kind of client education do we need to provide for KCS?
- prognosis for resolution is guarded
- usually life long treatment
- 15 - 20% may go into remission
- failure to treat will result in blindness
What is entropion?
eyelids roll in towards cornea
Which animal is entropion the most common in?
- common in dogs
- less common in cats
What are the different types of entropion?
- congenital (hereditary)
- acquired non-spastic
- acquired spastic
How does acquired non-spastic entropion occur?
- usually due to trauma or surgery
- chronic inflammaion
- scarring of the lid with contraction
- lid turns inward towards globe
How does acquired spastic entropion occur?
- usually secondary to painful corneal lesions or conjunctival inflammaion
What are the clinical signs of entropion?
- range from absent to severe
- blepharospasm, epiphora
- hair rubbing on cornea
- corneal pigmentation, vasculatization, ulceration
- chemosis, pain, photophobia
- rolling in of eyelid margins
How do we treat entropioin?
- medical: treat causes of spastic entropion, treat corneal ulceration
- surgical: temporary tacking, permanent
What kind of client education do we need to provide about entropion?
- avoid purchasing breeds known to have this defect
- carefully examine puppies
- dogs do not usually outgrow this condition
What is ectropion?
eyelid margins rolled away from eye
Which eyelid does ectropion affect the most?
What are the clinical signs of ectropion?
- may be asymptomatic
- vary with extent of the entropion
- debris accumulation (purulent)
- keratitis if severe (exposure)
- lid eversion
How do we treat ectropion?
- medical: clean accumulated discharge daily, topical lubricant
- surgical: wedge resection lateral canthus, technique to shorten lower lid
What is another name for a prolapsed third eyelid?
What is the third eyelid and what is its purpose?
- nictitating membrane
- is a protective structure
- assists in spreading tears
- covers the eye to protect it from injury
- produces tears
How does a patient get a cherry eye?
- Gland embedded in the third eyelid
- gland slips forward but remains underneath the conjunctiva
- exposure results in swelling and inflammation of the gland
Which animals typically get a cherry eye?
Young dogs less than 2years old
Describe what a cherry eye looks like.
- Round, reddened soft mass in the media, canthus
- possible mucous discharge
- unilateral or bilateral
- may be irritated
- usually not painful
How do we treat cherry eyes?
Surgical restoration of normal gland pposition surgical removal is a last resort-cancer
What are the two surgical restoration techniques for fixing cherry eyes?
- Pocket technique
- orbital rim tracking
What are the different problems with the structure of the globe?
- Corneal ulcers
- pigmentary keratitis
- lens luxation
What is another name for a corneal ulcer?
What are the 5 ayers of the cornea?
- Epithelium (outer)
- bowman's membrane
- descemet's membrane
- endothelium (inner)
What is a superficial corneal ulcer?
Loss of epithelium only
What is a stomal ulcer?
Loss of epithelium and some stoma
What is a desmetocele?
Stroma lost down to descemets membrane
What is perforation in descemets membrane?
Loss of aqueous humor, may have iris prolapse
What are the different causes of corneal ulcers?
- Trauma, chemicals, foreign bodies, KCS
- conformational abnormalities
- bacterial, fungal, viral
- immune mediated
- distichia, trichiasis, ectopic cilia
What are the clinical signs of corneal ulcers?
- Pain, blepharospasm, epiphora
- hyperemic conjunctiva
- ocular discharge (purulent)
- fluid leakage from wound
- upper respiratory infection in cats
How do we diagnose corneal ulcers?
- Thorough exam
- fluorescein stain-detects corneal ulcers and abrasions
- descemet's membrane will not stain
How do we treat corneal ulcers?
- Topical antibiotics
- topical atropine
- NSAIDs for uveitis
- systemic antibiotics
- contact lense protection
- oral lysine for cats
- surgery -grid keratectomy, third eye lid flaps, eyelid flaps, conjunctival flaps
What does topical atropine do?
- Decreases pain
- dilates pupil to prevent adhesions of iris to cornea
Does the corneal epithelium heal fast or slow?
How long does it take for superficial ulcers heal?
Do infected ulcers heal fast or slow?
How long does it take for indolent ulcers to heal?
Fail to heal after weeks of therapy
Should we use products containing cortisone for corneal ulcers? Why or why not?
No because cortisone delays wound healing and can make ulcers worse
How often should a patient with corneal ul era get rechecked?
What is glaucoma?
Increased intraocular pressure (IOP) beyond what is compatible with the health of the eye
What can glaucoma result in?
What is primary glaucoma?
What is secondary glaucoma?
Due to another disease affecting the drainage of the eye (uveitis, lens luxation, neoplasia, trauma)
What are the acute clinical signs of glaucoma?
- Ocular pain -rubbing eyes, hiding, personality changes
- ocular redness
- vision loss
- dilated pupil -slow to absent pupillary light reflex
What are the chronic clinical signs of glaucoma?
- Any acute sign
- buphthalmos -abnormal enlargement of the eye
- linear streaks in the cornea
- lens luxation
- pain, blindness
How do we diagnose glaucoma?
- measure both eyes for comparison
What are the two devices for tonometry?
- Schiotz tonometer
What is gonioscopy?
checks filtration angle
How do we treat glaucoma?
- Reduction of IOP
- may be able to preserve vision
- no known cure
- a true emergency
- mannitol - hyperosmotic
How do medications treat glaucoma?
- decrease aqueous humor production
- increase aqueous outflow
What are the different types of surgery for glaucoma?
- salvage surgery
What are gonioimplants?
What is cyclophotocoagulation?
Laser ablation of ciliary bodies
What is cyclocryotherapy?
Cold applied to the globe over the area of the ciliary body- partial destruction
What is salvage surgery?
- orbit implant
- Evisceration with implant
- intravitreal gentamicin injection - only on blind eyes - toxic to structures in the vitreous and the ciliary body
What are cataracts?
Opacity of the lens
What is the most common disease involving the lens?
What color does the lens change to with cataracts?
From clear to white or blue
What is the frequent cause of blindness in dogs?
What could cataracts be secondary to?
- Diabetes mellitus
- nutritional deficiencies
- electric shock
- lens luxation
What is senile nuclear (lenticular) sclerosis?
- Normal change in aging animals
- lens may appear gray or opaque
- vision is maintained
- can visualize fundus
- begins at around 7 years old
What are the clinical signs of cataracts?
- Progressive vision loss
- opaque pupil opening
- other systemic disease
How do we diagnose cataracts?
- Ophthalmic exam
- assess vision loss - obstacle course, lack of menace reflex, failure to track
- PLR - pupillary light reflex - normal
- serum profile for primary disease
How do we treat cataracts?
- Stabilize primary cause if any
- surgical removal if necessary
- treat uveitis or other inflammation in the eye
- if surgery is not an option, monitor yearly
What is phacoemulsification?
- Ultrasound - breaks up lens
- aspirate lens out with needle
- preferred technique for removing most cataracts
- can replace lens with intraocular lens prosthesis
- success rate about 95%
- usually a unilateral surgery
What do we need to educate clients on about cataracts?
- Cataracts are usually progressive
- most cataracts are inherited - do not use animal for breeding
- quality of life can be maintained
- do not move furniture around if animal is blind
What is anterior uveitis?
Inflammation of the iris, ciliary body, or choroid
What causes anterior uveitis?
- Bacterial, viral, mycotic, parasites, immune mediated
- lens induced - lens proteins
- trauma, systemic disease, rickettsial
- cats - FeLV, FIP, herpes
What are the clinical signs of anterior uveitis?
- epiphora, blepharospasm
- corneal edema (gray, white)
- chemosis, scleral injection
- cherry eye
- change in color of iris
How do we diagnose anterior uveitis?
- clinical signs
- blood work for systemic disease
- immunology screening panel (FeLV, FIP, FIV, mycosis panels)
- ultrasound of the eye
- tonometry - eye is usually soft
How do we treat anterior uveitis?
- treat underlying disease
- control inflammation
How do we control inflammation with anterior uvetitis?
- Banamine or aspirin
- topical opthalmic steroids and NSAIDs
- atropine - for pain and to prevent adhesions
What is PRA?
progressive retinal atrophy
What is the retina?
where the visual pathway begins
What does the retina consist of?
- photoreceptor cells - rods and cones
- arteries and veins which connect to the optic disc
- the optic disc connects to the optic nerve which connects to the brain
What are photoreceptors cells?
- sense light
- rods: black/white, low light
- cones: color, bright light
Does the retina have to be functioning normally for vision to occur?
What does PRA result in?
loss of vision
When do we start to see signs of PRA?
- as early as 6 months of age
- usually starts at middle age
What type of vision is lost first with PRA?
- loss of night/low light vision
- progresses to affecting day vision
What are the clinical signs of PRA?
- most cases - complete blindness
- cataracts often develop
Is there a cure for PRA?
Is there a treatment for PRA?
How do we diagnose PRA?
- retinal exam
- electroretinogram is abnormal
- DNA testing in some breeds
How do we treat PRA?
- no treatment
- instruct owners on ow to care for a blind pet
- do not breed animals with PRA
- CERF exams
What are CERF exams?
- Canine Eye Registration Foundation
- certifies dog free of heritable eye disease
- board certified veterinary ophthalmologist
- exam done yearly