Unit 2 - Feline Ophthalmology Flashcards
What are the general practices that you should maintain for a feline ophthalmic exam (room, restraint)?
Quiet room that can be darkened
Gentle restraint on the exam table and ‘less is more’ approach
If not compliant, wrap patient in a towel
Have assistant elevate rear end for you to view ventral cornea
What is the normal STT in cats?
> 9 mm/min
What is the preferred device to test IOP in cats?
TonoVet
If you need to use atropine in a cat, what form should you use? Why?
Use atropine ointment to minimize hypersalivation
When shouldn’t timolol be used in cats?
Cats with asthma - be careful regardless
What orbital condition results in a grave prognosis for a cats eye?
Proptosis
Eyelid agenesis causes what in cats?
Trichiasis and keratitis
What is the most common eyelid neoplasia in cats?
As a generality, are feline eyelid neoplasias typically benign or malignant?
SCC
Malignant > benign
What lacrimal conditions do brachycephalic cats typically get?
Fucntional nasolacrimal obstructions
What virus causes a lack of tear production in cats?
FHV-1
What is the most common cause of cataracts and lens luxation in cats?
Uveitis
What clinical signs are associated with feline conjunctivitis?
Blepharospasm
Tearing/discharge
Conjunctival redness +/- swelling (chemosis)
What is the common cause of conjunctivitis in cats (general)?
Primary pathogens are common
What primary pathogens are common causes of feline conjunctivitis?
Chlamydia felis
Mycoplasma felis and gatae
Feline herpesvirys-1
Calicivirus
What individuals are especially susceptible to feline conjunctivitis?
Young, immunosuppressed, sick, or stressed cats at highest risk
T/F: Feline conjunctivitis is one of the few conditions that can be treated with topical steroids.
False - do not, no bueno
What are the bacterial causes of conjunctivitis?
Chlamydia or Mycoplasma
What does bacterial conjunctivitis look like?
No corneal changes; more chemosis
How do you treat bacterial conjunctivitis?
Topical antibiotics - TID-QID: erythromycin, tetracycline, chloramphenicol, ciprofloxacin or ofloxacin
Systemic treatment - Doxycycline
What is the most common cause of feline conjunctivitis and keratitis/ulcers?
Feline herpesvirus-1
What cases of FHV-1 conjunctivitis require treatment?
More severe conjunctivitis
Concurrent keratitis or corneal ulceration
Severe rhinosinusitis, pneumonia, or dermatitis
Frustrated owners
How is FHV-1 conjunctivitis treated?
Antivirals:
Topical: Cidofovir 0.5% 1 drop BID or Idoxuridine 0.1% 5-6 times daily
Systemic: Famcyclovir 90 mg/kg po BID
Reduce stress, avoid steroids, nursing care
What systemic antiviral should not be used for FHV-1 conjunctivitis treatment?
Valacyclovir
How long should FHV-1 conjunctivitis be treated?
At least 2 weeks past resolution of clinical signs
What are ‘other’ FHV therapies?
Treat other issues
Analgesic
Immune boosting supplement
Proniotic
What used to be the old gold standard for the treatment of FHV-1 conjunctivitis?
Lysine
What is a possible complication of FHV1 conjunctivitis?
Symblepharhon
What is symblepharon?
Conjunctival +/- corneal adhesions
Why don’t you want to treat feline conjuntivitis with steroids?
It can make the infection worse
Remember: dogs can get allergic conjunctivitis, but cats do not
What are the causes of corneal ulceration?
FHV-1
Trauma - abrasions, cat stratch
Adnexal diseases (entropion)
How are corneal ulcers treated?
Topical antibiotic TID-QID: Erythromycin, oxytetracycline, chloramphenicol, tobramycin, ciprofloxacin, ofloxacin
+/- Atropine ointment SID-BID
+/- Pain medication
Antiviral tx if FHV-1
What topical antibiotics are not recommended for corneal ulcer treatment in cats?
Neomycin/polymyxin drugs
When should corneal ulcers be rechecked after treatment has been initiated?
3-5 days
When should corneal ulcers heal?
Within 7-10 days
What should you do in cases of non-healing superficial ulcers?
Look for a persisting cause
Debride loose epithelium with sterile dry cotton swab
Diamond burr or superficial keratectomy (NO GRID)
When is culture and cytology indicated in corneal ulcer cases?
If they are infected or melting
What is the recommended treatment for infected or melting ulcers?
Aggressive treatment - frequent antibiotics, serum 6-8x daily, atropine SID-BID, and systemic NSAID +/- analgesic
When should infected or melting ulcers be rechecked?
In 1-2 days
What is a corneal sequestrum?
A necrotic area of the cornea
What clinical signs/findings are associated with corneal sequestrium?
Brown to black, round to oval lesion in central/paracentral cornea
Variable signs of pain
Variable corneal vascualrization and edema
What breeds are predisposed to corneal sequestrum?
Persian, Himalayan, burmese
What can cause corneal sequestrum?
Heredity - Brachycephalics
Non-healing ulcer
Chronic irritation
FHV-1
How are corneal sequestrum diagnosed?
Appearance
How is corneal sequestrum treated?
Possibly benign neglect
Keratectomy surgery +/- graft
Medications (abx, lubricant, antiviral?)
T/F: Corneal sequestrum can recur or happen in the opposite eye
True
What clinical signs/findings are associated with eosinophilic keratitis?
Proliferative pinkish-white, vascularized lesion
Not usually painful
May be edematous or irregular
Starts near limbus
Unilateral or bilateral
What is the cause of eosinophilic keratitis?
Immune-mediated
Suspect FHV-1
How is eosinophilic keratitis diagnosed?
Corneal cytology - eosinophils +/- mast cells
How is eosinophilic keratitis treated?
Topical - steroid (pred acetate or dex sp), cyclosporine A or tacrolimus BID, megestrol acetate antiviral
Systemic - L-lysine
What is the Sebbag protocol for eosinophilic keratitis?
SQ triamcinolone acetate 0.2 mg/kg + topical cidofovir + topical tacrolimus
What is acute bullous keratopathy?
Spontaneous edema (DM rupture)
How is acute bullous keratopathy treated?
Stabilize cornea to prevent rupture - corneal graft or third eyelid flap (2-3 weeks)
Abx and 5% NaCl meds
What is the prognosis for acute bullous keratopathy?
Good
What may be a risk factor for acute bullous keratopathy?
Cyclosporine or steroid use
What clinical signs/findings are associated with feline uveitis?
Enophthalmos, third eyelid elevation, photophobia
Conjunctival and episcleral injection
Corneal edema, ciliary flush, keratic precipitates
Aqueous flare +/- fibrin and cells
Miosis and iris changes
Fundus changes
low IOP
What are the causes of uveitis?
Infectious
Immune-mediated - chronic lymphoplasmacytic uveitis
Neoplasia - lymphosarcoma
Trauma
Idiopathic
What work-up is recommended for uveitis cases?
complete ocualr exam and diagnostics
complete physical exam
Diagnostic tests - CBC, chemistry, UA, BP, infectious disease testing, LN aspirate and cytology, radiographs, ocular ultrasound
What is the recommended therapy for uveitis?
Address underlying cause if identified
Topical therapy - prednisoolone acetate, atropine
Systemic therapy - NSAID or prednisolone, doxycycline
How long should you treat uveitis for?
At least 2 weeks past resolution of clinical signs
What is the recommended course of treatment for end-stage uveitis?
Enucleate irreversibleblind eyes
What is diffuse iris melanoma?
Progressive iris pigmentation - malignant melanoma
What is the common signalment for melanosis?
middle-aged to older cats
What should be monitored to determine if it is a diffuse iris melanoma or melanosis? How often?
Monitor progression/extent, surface dusting, extension into iridocorneal angle, pupil changes, intraocular pressure
Monitor every 3-6 months
How is diffuse iris melanoma treated?
Diode laser (early)
Enucleation - preanesthetic imaging, ocular histopathology
What concerning ocular findings are indicative of diffuse iris melanoma?
Iris swelling or dyscoria
Pigment cells in aqueous humor or on lens
Rapid pigment progression
Glaucoma
Why should you not put traction on the globe during an enucleation in a cat?
You could damage the optic nerve or chiasm resulting in blindness in the ‘good eye’
When performing a cat enucleation, what do you need ot make sure to remove?
All secretory tissues - don’t want a postop cyst
What are the causes of feline glaucoma?
Uveitis
Lens luxation
Neoplasia
What is aqueous misdirectio syndrome?
A rare syndrome that causes feline glaucoma where aqueous humor moves posteriorly into the vitreal cavity
What clinical signs and findings are associated with aqueous misdirection syndrome?
Older felines with increased IOP
Anisocoria
Shallow anterior chamber
How is aqueous misdirection syndrome treated?
Dorzolamide +/- Timolol (BID-TID)
Possible surgery
What is the signalment for hypertensive retinopathy?
Older cats - >10 years
What are the clinical signs/findings associated with hypertensive retinopathy?
Dilated pupils
Acute vision loss
Hyphema
Retinal hemorrhage
Retinal detachment
Subtle retinal cobblestone appearance if fluctuating detachments
What are the causes of hypertensive retinopathy?
Kidney disease
Hyperthyroidism
Heart disease
Endocrine disease
Primary hypertension
T/F: You should always perform a 30 second ophtho exam during all PEs
True
How is hypertensive retinopathy diagnosed?
Visible ocular/retinal changes
Systolic pressure of >160 mmHg
CBC/Chem/T4/UA
How is hypertensive retinopathy treated?
Amlodipine
+/- topical steroid if hyphema
Address underlying disease
What causes toxic retinal degeneration?
Systemic enrofloxacin
What clinical signs are associated with toxic retinal degeneration?
Dilated pupils
Acute blindness
