Feline Opthamology Flashcards
What is eyelid agenesis?
- Absence of a portion of the eyelid
- Sequalae - secondary trichiasis and exposure keratoconjunctivitis
- Most common in cats and horses
- cats - upper temporal eyelid
- commonly associated w/ other ocular abnormalities, PPM, retinal dysplasia, cataracts)
- Horses - upper nasal eyelid
- cats - upper temporal eyelid
What is the treatment for eyelid agenesis?
surgical relocation of other skin
What is Corneal Sequestrum?
- Area of corneal degeneration w/ amber to brown discoloration
- Usually in the central/paracentral cornea
- Variable vascularization
- Variable ocular pain
- Unique to cats
- more common in Persians, Himalayans
What is the treatment for Corneal Sequestrum?
- Surgical removal:
- keratectomy +/- conjunctival graft
- cornealconjunctival transposition
- cyanoacrylate glue
- lamellar or penetrating corneal transplant
- Recurrence is always possible!
What is Eosinophilic Conjunctivitis/Keratoconjunctivitis?
- Proliferative, white to pink, irregular, vascularized lesion
- Commonly originates from the nasal or temporal limbus
- Conjunctiva may be affected
- More often unilateral
- Variable ocular discomfort
How is Eosinophilic conjunctivitis/keratoconjunctivitis diagnosed?
- Eosinophils on cytology
What is the treatment for Eosinophilic Conjunctivitis/Keratoconjunctivitis?
- Topical
- Prednisolone acetate 0.1% TID to QID
- Dexamethasone 0.1% TID to QID
- Optimmune 0.2% cyclosporine BID
- Cyclosporine 1 or 2% BID
- Tacrolimus 0.02 or 0.03% BID
- Topical megestrol acetate TID
- Systemic
- Prednisolone
What is the Prognosis for Eosinophilic Keratitis?
- Usually favorable
- Treatment may be long term
What do corneal ulcers from Feline Herpesvirus 1 look like?
- Geographic
- Dendritic
- Stromal keratitis
How is FHV-1 diagnosed?
- Clinical Signs
- Conjunctival cytology
- intranuclear inclusions, neutrophils
- PCR - sensitive and specific
- IFA - insensitive
- fluorescein stain may cause false positive
- Serology (serum neutralization titer - insensitive
- Virus isolation
- Definitive dx for acute infection
- Insensitive for chronic infection
What is the treatment for Feline Herpesvirus?
- Topical Treatment - Prevent bacterial infection
- Cidofovir 0.5% solution
- compounding pharmacy
- 2 times daily
- Idoxuridine 0.1% solution
- Compounding pharmacy
- 4-6x daily
- Trifluridine 1% solution
- Viroptic and generic
- Refrigerated
- Topically irritating
- Cidofovir 0.5% solution
- Systemic Treatment
- Famciclovir
- 250 mg or 125 mg tablets
- 30-40 mg/kg BID to TID PO
- Lysine
- 250 mg PO BID kittens
- 500 mg PO BID cats
- Famciclovir
Why should valacyclovir be avoided in cats?
potential for fatal hepatic and renal necrosis
what are possible eye complications of FHV-1?
- Globe rupture
- Symblepharon
Is Glaucoma common in cats?
- Primary glaucoma is very, very rare
- Secondary glaucoma
- Uveitis
- Intraocular neoplasia
- Feline aqueous misdirection syndrome
What is the treatment for glaucoma in cats?
- Topical carbonic anhydrase inhibitors (Dorzolamide 2%)
- Beta blockers (0.25%)
- Latanoprost ineffective in cats
- Do not use oral carbonic anhydrase inhibitors
- more sensitive to adverse effects
What is Feline Aqueous Humor Misdirection Syndrome
- Generally in older cats
- Aqueous Humor shunted into the vitreous
- shifts lens and iris anteriorly
- Results in Anisocoria and Shallow anterior chamber
- IOP often not elevated initially
What is the treatment for Feline Aqueous Humor Misdirection Syndrome?
- Topical Carbonic anhydrase inhibitors BID to TID
- Monitor IOP q1-3 months (both eyes)
- Refer for surgery if unresponsive to medications
Do cataracts occur in cats?
- Primary inherited cataracts are rare
- Most are secondary:
- Anterior uveitis
- Trauma
- Lens luxation
What is Hypertensive Retinopathy?
- Generally in older cats (>10yrs)
- Present with dilated pupils or vision loss
- Causes:
- hyphema
- Vitreal hemorrhage
- Retinal hemorrhages
- Retinal detachment
- Retinal vessel tortuosity
What is the etiology of Hypertensive Retinopathy
- Idiopathic - 20%
- Chronic Kidney Disease 19 - 65%
- Hyperthyroidism 10 - 20%
- Others:
- Diabetes mellitus
- Primary aldosteronism
- Pheochromocytoma
- Chronic anemia
how is hypertensive retinopathy diagnosed?
- Systolic blood pressure
- >160 mmHg
- CBC/Chemistry Panel/UA/T4
What is the treatment for Hypertensive Retinopathy
- Treat underlying condition
- Antihypertensive medication
- Amlodipine
- 0.18 - 0.22 mg/kg PO SID
- 0.625 mg PO SID
- Amlodipine
- Goal BP < 150 mmHg
Why should Enrofloxacin be avoided in cats?
- Can cause acute retinal degeneration
- may occur even at recommended dose (2.5mg/kg BID)
- especially in cats with impaired drug metabolism (renal/hepatic disease)
- IV administration may increase risk of retinal toxicity
- may occur even at recommended dose (2.5mg/kg BID)
- Most cases of blindness is permanent
- Only use if there is no alternative
- use at lowest dose for the shortest amount of time
Are other fluoroquinolones safe to use in cats?
- Consider that all fluoroquinolones may have the potential to induce ocular lesions in cats
- all should be used with caution
Why should Polymyxin B be avoided in cats?
- linked to anaphylaxis and death
- usually topical ophthalmic products
What is a Diffuse Iris Melanoma
- Most common feline primary intraocular tumor
- Malignant melanocytic neoplasm
- Slow, progressive, often multifocal areas of pigmentation of the iris
- Secondary glaucoma from involvement of the iridocorneal angle
How can Diffuse Iris Melanoma (DIM) be distinguished from Iris Nevus?
- Iris Nevus (think of it like a freckle of the Iris - benign)
- Histopathology
- DIM:
- Progressive growth
- Raised, velvety surface
- Exfoliating cells in the anterior chamber
- Involvement of the iridocorneal angle
- Secondary glaucoma
- DIM:
What is the prognosis of DIM?
- Metastasis to the Liver and Lungs
- late in the disease
- Prognosis - related to location in the iris
- Confinement to the iris - better prognosis
- Involvement of the iridocorneal angle - poor prognosis
What are the treatment options for DIM?
- Monitor for progression
- Photos of drawings in the medical record
- Recheck at 2-4 month intervals
- Possible Laser ablation
- Enucleation:
- only if metastasis is not present
