Ophtho final- some old ALL the new stuff – Flashcards
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Review: Conjunctivitis in DOGS causes Treatment
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Causes in dogs: usually secondary to MANY causes (KCS, entropion, etc) but rarely primary (allergies, infection etc) Tx in dogs: tx underlying cause! antibiotics and steroids if no ulcer
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Review: Conjunctivitis in CATS causes Signs Treatment
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Signs if from bacteria- Chemosis Tx if bacterial: Antibiotics Doxy gets rid of carrier state Signs if from virus- ULCERS Tx if from virus- Self limiting! Topical: cidofovir, idoxyuridine Systemic: famciclovir NOT VALCYCLOVIR L lysine lifelong to reduce recurrence
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Review: Corneal ulcers. Cause? sequelae? tx?
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Causes- Too numerous (injury, conformation) sequelae- reflex uveitis Tx Topical antibiotic NO steroids! Atropine, NSAIDs *NO 3rd eyelid flap or tarsorrhaphy
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Review Indolent ulcers cause? tx?
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Cause: spontaneous in older boxers Tx: -Debride with cotton 30% effective -Grid keratotomy 90% effective -Keratectomy 99.9% effective- slice out what is not healing
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Review Pannus (chronic superficial keratitis) Signalment? cause? signs: tx:
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GSD, greyhounds lymphocytes and plasma cells- lateral to medial cause: immune with UV factor signs: Neovascularization, pigment, scars Tx: doggles, steroids, cyclosporine, tacrolimus
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Review Exposure keratitis cause? tx?
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Cause: too many to name Tx: ID the cause and treat (ex: lagophthalmos), and LUBE!!!!!!
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Review: pigment keratitis Signalment? cause? tx?
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brachycephalics chronic irritation/inflammation tx: treat cause, cyclosporine, tacrolimus, steroids, MEDIAL CANTHOPLASTY, keratectomy if blind
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Review: Corneal dystrophy Signalment? signs? tx?
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purebreds sparkling cornea but NO VISION LOSS tx: none or low fat diet
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Review: juvenile corneal dystrophy signalment? tx?
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Many breeds, YOUNG tx: none- self limiting in 10 weeks NON painful
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Review: corneal degeneration Signs? tx?
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Signs Corneal opacities (lipid, Ca, etc)- can lead to ulcers Tx- NO STEROIDS- they increase disposition. Use EDTA, keratectomy
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Review: perilimbal lipid deposits Tx?
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do a thyroid panel! then address underlying cause
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Review: superficial punctate multifocal lesions who gets it? signs? tx?
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Dachshunds and shelties signs: PAIN, lesions tx: cyclosporine
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Review: endothelial dystrophy signalment? signs? tx?
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Boston, chihuahua, dachshunds signs: corneal edema, NOT pain tx: NaCl to pull out fluid SURGERY- thermokeratoplasty, conjunctival graft, corneal transplant
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Review: what is the main difference between endothelial dystrophy and endothelial degeneration?
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Degeneration is PAINFUL
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Review: Feline ulcers causes? tx?
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causes: FHV1, trauma, adnexal disease tx: antibiotics but Atropine, NSAID, antiviral
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Review: these TWO tx are contraindicated in feline ulcers
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Neo/poly/bac- hypersensitivity grid keratotomy- sequestra formation
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Corneal sequestra signalment? cause? tx?
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Persian, himalayan, burmese Causes: irritation, FHV1 Tx: benign neglect, keratectomy, meds and lube
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Review: eosinophilic keratitis Causes? signs? diagnosis? tx?
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Immune mediated or FHV1 cause signs: no pain, vascular lesions starting near limbus diagnosis- eosinophils via cytology tx: L lysine works great!, Steroids, cyclosporine
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The uvea is the iris, choroid and ciliary body, which of these three is considered the "posterior uvea"
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choroid
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What is heterochromia irides
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more than one color in the iris
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What is corpora nigra
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in horses knobby structure juts out from the top of the iris and functions to shade the pupil from glare
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Define mydriasis
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dilation of pupil
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Define miosis
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constriction of the pupil
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What are the three zones of the iris from outside in?
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ciliary iris collarette pupillary iris
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What are some roles of the ciliary body?
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Produces aqueous humor allows outflow of aqueous humor nourishes cornea and lens allows accomodation after lens shape change
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explain the role of the anterior uvea when focusing on the distant object
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The ciliary muscle will be relaxed and the lens will be flattened but the suspensory ligament will be taut
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explain the role of the anterior uvea when focusing on a near object
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The ciliary muscle will be contracted and the lens will be rounded but the suspensory ligament will be relaxed
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What maintains the clarity of aqueous humor?
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blood ocular barrier
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breakdown of the blood ocular layer results in what?
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uveitis
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Anterior uveitis defined
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iris and ciliary body aka iridocyclititis
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Posterior uveitis defined
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Choroid only USUALLY also involves retinitis
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What is the term for anterior AND posterior uveitis?
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panuveitis
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Signs of anterior uveitis
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blepharospasm epiphore enophthalmos 3rd eyelid elevation photophobia lower vision decreased IOP Episcleral congestion corneal edema and neovascularization opacities in anterior chamber keratic precipitates miosis
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why does anterior uveitis cause lower IOP
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poor ciliary body function
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What are the different anterior chamber opacities
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aqueous flare (protein) hyphema (RBC's) Hypopyon Fibrin
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What is the tyndall effect?
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aqueous flare (light scattering by particles)
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What are keratic precipitates?
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WBC and protein accumulation on corneal endothelium with uveitis
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What is rubeosis irides?
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iris hyperemia due to anterior or panuveitis
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If you see hyperpigmentation with uvieitis, what does that tell you?
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chronic!
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Clinical signs of posterior uvieitis
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hyporeflective tapetum white/grey areas in non tapetum retinal detachment
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Sequelae of uveitis
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Cataract synechiation (usually posterior) Iris bombe secondary glaucoma
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What is synechiation?
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Adhesions of the pupil margin to the lens which cause an obstruction of the flow of aqueous humour (iris bombe)
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primary causes of uveitis
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trauma corneal ulcer intraocular neoplasia cataract
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What are some non ocular causes of uveitis?
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infection metastatic neoplasia
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What is a metastatic neoplasia that can cause uvieitis more commonly
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lymphoma (hemangiosarcoma occasionally)
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What is uveodermatologic syndrome
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Immune mediated attack on melanin (akita, husky) Often severe unrelenting panuveitis
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Breeds predisposed to uveodermatologic syndrome
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akita husky others
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Tx of uveodermatologic syndrome
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AGGRESSIVE corticosteroids azathioprine
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Idiopathic uveitis is a diagnosis of exclusion. It may be up to ____% of cases
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50%
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Where do you begin when determining the cause of uveitis
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Exclude primary ocular causes first then take a systemic approach
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When trying to determine the cause of uveitis, when will it be helpful to sample aqueous humor
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ONLY in the case of lymphoma so not rewarding most times
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Is sampling the subretinal exudate a good method to determine the cause of uveitis?
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not really hard, needs anesthesia, complications are common so ONLY do it if they are blind
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Is histopath useful for determining the cause of uveitis?
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Only if it is infectious or neoplastic. BUT reserve for permanently blind or painful eyes
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T or F: you should start treatment while lab tests are running for the cause of the uveitis
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true
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Topical anti-inflammatory drugs are contraindicated for ____________
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reflex uveitis ulcers
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Which is more effective as a topical anti-inflammatory: corticosteroids or NSAIDS
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corticosteroids (prednisolone acetate)
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how often should topical corticosteroids be given?
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3-6x
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T or F: nsaids are not useful for severe uveitis but are useful for cataract induced uveitis
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true
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Are cyclosporine and tacrolimus useful for uveitis?
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nope poor penetration to uvea
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What topical mydriatic is useful vs. uveitis and why?
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atropine sulfate 1% it paralyzes iris muscles and ciliary body muscles to improve comfort ONLY 1-2x per day needed
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side effects of topical atropine sulfate as a mydriatic
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GI stasis decreased secretions/salivation hypersalivation in cats due to nasolacrimal drainage of the drug (use ointment)
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Why is atropine sulfate used over tropicamide for uveities?
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Tropicamide is less potent and shorter duration
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Mydriatics help to prevent ___________
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synechiation
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What type of uveitis warrants systemic anti-inflammatories
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posterior uveitis or SEVERE anterior uveitis
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Are corticosteroids or NSAIDs more effective SYSTEMICALLY for uveitis?
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corticosteroids but watch out for PU/PD, immune suppression
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Which NSAID is better for systemic uveitis tx, flunixin or phenylbutazone
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flunixin
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What is the thought behind equine recurrent uveitis?
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Lepto infection- the antigens are similar to that of the ocular proteins. The immune system attacks both
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Tx of equine recurrent uveitis is the same as other uveitis tx BUT this can also be done and is highly effective
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suprachoroidal cyclosporine implants
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Two types of uveal masses
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uveal cysts uveal neoplasia
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What do uveal cysts look like?
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brown/tan spherical structure in anterior or posterior chamber
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Uveal cysts are commonly incidental EXCEPT....
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they can be associated with glaucoma and immune mediated uveitis in goldens, danes and american bulldogs
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T or F: usually uveal cysts need no tx
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true
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What is the most common uveal neoplasia
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melanocytoma/melanoma
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are uveal melanomas usually benign or malignant?
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benign but locally destructive
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Common secondary changes with uveal neoplasia
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uveitis glaucoma
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Tx of uveal neoplasia
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Enucleation
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What is the most common intraocular tumor in a cat
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diffuse iris melanoma
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diffuse iris melanoma in cats, usually malignant or benign?
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malignant
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Common sequelae of diffuse iris melanoma in cats
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glaucoma
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Tx of diffuse iris melanoma in cats
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limited laser ablation enucleation
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What is iris nevus and how do you differentiate from diffuse iris melanoma
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monitor with photos iris nevus is a freckle
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What are some incidental findings of a uveal exam
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Heterochromia irides uveal cysts iris nevi persistant pupillary membranes (PPM) Iris atrophy Iris hypoplasia/coloboma
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do persistent pupillary membranes usually extend iris to iris or iris to cornea/lens?
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Usually iris to iris but can do both
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how can you tell persistent pupillary membranes (PPMs) from synechia?
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PPM is from iris collarette to iris, cornea or lens Synechia is from pupil margin of iris to lens or cornea
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is iris atrophy common or rare?
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common in older dogs may limit pupil constriction (PLR) looks like thin iris or irregular pupil margin
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difference between iris hypoplasia and coloboma
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hypoplasia - thin coloboma- focal absence (hole)
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Differentials for corneal edema
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uveitis glaucoma anterior lens luxation corneal ulcer corneal endotheial dystrophy
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Differentials for diffuse hyperpigmentation
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Chronic uveitis diffuse iris melanoma (cats) pigmentary dispersion medication (topical prostaglandins)
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Uveitis and Horner's look the same in cats because they share these clinical signs
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Enophthalmia 3rd eyelid elevation miosis ptosis in horner's (dropping of upper lid) blepharospasm of uveitis (squint)
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uveitis and glaucoma can appear similar, how can you tell them apart?
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pupil size (uveitis is miosis, dilated with glaucoma) tonometry- intraocular pressure measurement needed for diagnosis
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Developing lens nutrition comes from where?
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the pupillary membrane from the iris the tunica vasculosa lentis from hyaloid artery
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T or F: the lens continues to grow throughout life
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true
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hardening of the lens with age is called?
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nuclear sclerosis
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how thick is the canine lens capsule?
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anterior is 50-70 microns posterior is 2-4 microns
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what makes up the lens
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lens capsule anterior epithelium fibers equator nucleus cortex
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explain the orientation of the Y sutures of the lens
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in anterior lens they are upright posterior- upside down
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What suspends the lens
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zonules from the ciliary body
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is the lens vascular?
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nope
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What gives the lens its nutrition
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aqueous humor
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Purpose of the lens?
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refraction- bends the light for focus
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term for nearsightedness, normal, farsightedness?
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near- myopia normal- emmetropia far- hyperopia
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What are some lens congenital defects
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Lens coloboma microphakia sperophakia aphakia cataract persistent vasculature PPM
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What are the possible types of congenital lens defects related to vasculature
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persistent hyaloid artery persistent tunica vasculosa lentis persistent hyperplastic primary vitreous
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Persistent hyperplastic primary vitreous is hereditary in who?
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doberman staffordshire bull terrier bouvier des flanderes
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Why do humans need reading glasses over 40
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nuclear sclerosis
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What is nuclear sclerosis and what MUST MUST MUST you differentiate it from?
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normal aging process that causes increased density of the lens as lens fibers grow only minimally affects vision must differentiate from cataract!! you can retroilluminate through sclerosis
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Define cataract
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opacity in the lens or lens capsule
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You classify a cataract based on what?
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etiology age of onset location in the lens stage of development
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if a patient has a severe cataract, does it have a PLR
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YES, KNOW THIS
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most common cause of cataract in dogs?
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hereditary! KNOW THIS
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Most common cause of cataracts in cats and horses
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secondary to uveitis
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What are some causes of cataracts
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hereditary (NOT congenital) metabolic Secondary to uveitis trauma radiation toxic causes
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What metabolic disorders can lead to cataracts
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diabetes mellitus galactosemia milk replacer hypocalcemia (hypoparathyroidism)
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Why would a history of coccidiodies infection be related to a cataract?
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Ketoconizole is toxic and can cause cataracts
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What causes the lens to look like a white snow globe?
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hypocalcemia
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cataract is considered juvenile if the animal is how old?
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1-5 years (classic for huskys)
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How do you determine the location of the cataract?
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Direct exam and retroillumination pupil MUST be dilated
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Cataract stage terminology
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Incipient- <15% of the lens Immature 15-99% Mature- 100%, no tapetal reflection, blind hypermature- resorption of the cataracts
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What causes Intumescent mature cataracts?
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diabetes
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Explain hypermature cataracts
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"the grape is becoming a raisin" Highly variable appearance as it is resorbed. May again see tapetal reflection and may regain vision
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what is morgagnian cataract?
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complete resorption of the cortex and the nucleus "sinks to the bottom of the lens
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with cataracts, will they have a menace response?
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NO but they WILL have PLR response
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MOA of diabetic cataracts
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high blood glucose increases glucose in the eye which overwhelms hexokinase enzyme so it gets metabolized by aldose reductase to sorbitol which accumulates in the lens and draws in water leading to cataract
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Who is the most susceptible to diabetic cataracts and why?
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Rat>dog>mouse depends on how much aldose reductase they have
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What is phacolytic uveitis?
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leaking of some lens proteins through the intact lens capsule (common in diabetic, hypermature and some juvenile cataracts)
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How is phacolytic uveitis different from phacoclastic uveitis?
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phacoclastic is a full rupture of lens proteins causing SEVERE inflammation- it requires meds and maybe surgery ASAP
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Cataracts surgery When to refer? when to do surgery?
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Refer early! Surgery happens when vision is lost- ideally whem immature and no lens induced uveitis Advanced immature state is the right time- this is before many complications arise
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Treatment or prevention of cataract induced uveitis
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Topical NSAID (Diclofenac) Topical steroid Systemic anti-inflammatories (corticosteroids if not diabetic, NSIAD if diabetic)
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Can you prevent diabetic cataracts?
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No proven prevention of diabetic cataracts but Ocu-GLO or Kinostat shows promise Aldose reductase inhibitor 3x daily prevents formation of sorbitol (kinostat) Ocu-globe- a neutroceutical
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How much does elective cataract surgery cost?
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$3500-$4000
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What does Gonioscopy do?
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evaluates the iridocorneal angle before cataracts surgery
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Why do an ocular ultrasound before cataract surgery
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look for retinal detachment (sea gull)
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if you do cataracts surgery should you recommend a prostetic lens?
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ALWAYS recommend a lens Also prevents post op issues with capsular fibrosis since the lens capsule is still there
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if you remove the lens with cataracts surgery will the dog be blind
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Dogs without a lens can still see but it is still recommended to put in a lens
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post op consideration when fixing cataracts
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The surgery creates uveitis- treat DURING AND AFTER with anti-inflammatories
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success rate of cataracts surgery? Common comlplications?
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85-90% successful but failures are BAD uveitis glaucoma retinal detachment endophthalmitis (Bostons are worse)
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Who is predisposed to a primary lens luxation
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terriers! also shar pei, border collie, GDS
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Heredity behind lens luxation, how do you test for predisposition
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ADAMTS17 mutation- genetic test
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Lens luxation can be hereditary or secondary. What is it commonly secondary to?
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glaucoma uveitis trauma intraocular tumor cataract
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if you see lens luxation in horses or cats, your #1 differential is what?
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uveitis
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Iridodenesis vs. phacodenesis
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Iridodenesis- quivering of iris Phacodenesis- quivering of lens With a lens SUBluxation, when the eye darts one way the iris or lens will quiver
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T or F: If the vitreous is coming into the anterior chamber, it is pathognomonic for lens subluxation
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False!
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Anterior vs. posterior lens luxation
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Complete detachment 360 around of the zonules Anterior: lens goes in front of iris Posterior- may sink down deep in anterior chamber
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Tx of anterior lens luxation
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EMERGENCY if they are still visual Trans-corneal reduction or lens extraction (go back later with fake lens) THEN treat glaucoma- mannitol IV, anhydrase inhibitors
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What should you NEVER give if you have anterior lens luxation
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miotics like pilocarpine, latanoprost- they would constrict the pupil and make the lens "stuck" in front of the iris
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is posterior lens luxation an emergency
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nope!
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Lens subluxation tx if anterior
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proactive removal of lens or medical therapy BID to keep pupil miotic (OWNER COMPLIANCE!!!)
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Posterior lens subluxation tx
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non necessary if it is in fixed position miotic therapy if there is a chance it could shift you could just remove it
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The vitreous makes up how much globe volume?
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2/3
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Vitreous humor composition
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99% water 1% hyaluronic acid and collagen
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Purpose of the vitreous?
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support lens maintain globe shape transmits light to retina supports retina
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what is asteroid hyalosis
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small white particules (Ca and P) that move with eye movement ("floaters")
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glaucoma defined
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increased IOP from any of a number of disease that do not allow normal optic nerve/retainal function resulting in vision loss
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is glaucoma a diagnostic term
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nope it refers to increased pressure but can be from many causes
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What makes aqueous humor, where it is and how does it drain?
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ciliary body makes it posterior and anterior chambers contain it iridocorneal angle drains it
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What connects the base of the iris to the cornea
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pectinate ligaments
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normal IOP in dogs? cats? horses?
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dogs- 12-25 cats- 10-20 horses 15-30 mmHg
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aqueous humor production has an active and passive component. What two things must be stimulated for active production
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carbonic anhydrase beta adrenergic stimulation (pharmacologic implications)
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What are the two mechanisms for aqueous humor outflow
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Conventional- the majority of outflow (iridocorneal angle) Uveoscleral (unconventional)- minority of outflow
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Conventional aqueous outflow makes up what % of outflow in dogs? cats? horses?
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dogs 85 cats 97 horses 50
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describe the pathway of conventional outflow of aqueous humor
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Posterior chamber anterior chamber through iridocorneal angle via pectinate ligaments to the angular aqueous plexus and then into systemic venous system
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describe the pathway of UNconventional outflow of aqueous humor (oveoscleral)
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Posterior chamber anterior chamber base of iris ciliary body suprauveal space (between uvea and sclera) outflow through sclera
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T or F: glaucoma is never due to increased aqueous humor production and always due to an outflow problem
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true
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aqueous outflow is usually impaired via what route
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pupil OR conventional outflow pathway (iridocorneal angle most common)
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signs of glaucoma vary and include... (for your reference)
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Buphthalmia blepharospasm epiphora enophthalmia 3rd eyelid elevation "migraine sensation" increased IOP vessel congestion corneal edema and neovascularization mydriasis (dilated) lens subluxation aphakic cresent Haab's striae optic nerve head cupping retinal degeneration
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humans pass out at what IOP common of dogs with glaucoma?
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They get a migraine at 35-40, pass out at 45.
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T or F: elevated IOP alone is sufficient for glaucoma diagnosis
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FALSE can be a restraint artifact
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tonopen vs. tonopet
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Tonopen- flattens the cornea, instrument calculates pressure that it takes to flatten cornea Tonovet- newer. Gun like- shoots out a plastic probe and the speed that it bounces back determines IOP
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how can you tell buphthalmia from exophthalmia
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buphthalmia- enlarged cornea exophthalmia- more visible sclera
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You are blind if you have buphthalmia UNLESS you are what breed/animal
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Shar peis puppies cats horses
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What is Haab's striae
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Stretch marks in the cornea with glaucoma- KNOW THIS SIGN (cracks in descement's membrane)
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What is optic nerve head cupping?
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happens with glaucoma optic nerve head cupping is when there are no blood vessels over the nerve head as it is pushed posteriorly
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with glaucoma, do you get retinal detachment or degeneration
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degeneration! Tapetal hyperreflective retinal vascular attenuation
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Classification of glaucoma
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primary- without preexisting disease secondary- sequelae from other intraocular diseases
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Primary glaucoma is common in who? rare in who? it is usually unilateral or bilateral?
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50% of dog cases RARE in cats, horses usually bilateral within months or years but not at presentation
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SEcondary glaucomas is more common in who?
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50% in dogs MOST COMMON form for horses and cats
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three classifications of primary glaucoma
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Characterization is based on the iridocorneal angle appearance open angle closed angle pectinate ligament dysplasia
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term for visualization of the iridocorneal angel
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Gonioscopy (uses goniolenses)
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The iridocorneal angle is able to be directly assessed in who?
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cats horses
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overview of open angle primary glaucoma: how does it appear on gonioscopy? onset? cause? predisposition?
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Normal appearance on gonioscopy insidious onset cause unclear beagles and norweigian elkhounds
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overview of narrow/closed angle primary glaucoma: how does it appear on gonioscopy? predisposition?
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it looks squished via gonioscopy More common spaniels, samoyeds, husky's, labs, sharpei, chow
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overview of pectinate ligament dysplasia caused primary glaucoma: how does it appear on gonioscopy? predisposition?
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Solid sheets of tissue span the iridocorneal angle, possibly with "flow holes"
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T or F: primary glaucoma is breed related
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true
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T or F: you should treat the eyes prophylactically for primary glaucoma
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True when one eye is affected the other will be affected sooner or later
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What are the three big causes of secondary glaucoma we need to know
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Uveitis Intraocular neoplasia Lens luxation
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how does secondary glaucoma occur
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"clogging" of the conventional outflow pathway with protein or debris OR obstruction of the flow at the pupil
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These three things cause the aqueous humor flow to be thicker leading to clogging of the conventional pathway and secondary glaucoma
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uveitis hyphema intraocular neoplasia
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What are some causes of secondary glaucoma when it is caused by pupillary block?
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Uveitis w/ iris bombe lens luxation (anterior) cataracts (intumescent) aqueous humor misdirection syndrome
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Iris melanoma causes what type of glaucoma in cats?
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secondary due to clogging of the conventional pathway (know this?)
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T or F: pupillary block is less of a problem in cats and horses even though secondary glaucomas is more common in these species
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true
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how does iris bombe from anterior uveitis lead to secondary glaucoma
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pupil block via posterior synechia (the iris sticks to the lens all 360 degrees around preventing flow)
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how does intumescent cataracts lead to glaucoma?
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secondary glaucoma because the big fat cataract pushes the pupil forward and blocks flow out the pupil
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Overview of aqueous humor misdirection syndrome
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aqueous humor flow backwards into vitreal cavity which forces everything forward causing pupillary block
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Who gets aqueous humor misdirection syndrome and when?
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Spontaneous in cats post lens-extraction in dogs
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what is the KEY feature of aqueous humor misdirection syndrome
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shallow anterior chamber (between cornea and iris)
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principles of glaucoma management
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must know primary vs. secondary recognize signs prognosticate vision- acute is better than chronic for sight lower the IOP ASAP
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medical tx is likely to fail for which type of glaucoma?
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primary- it will fail within a year
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What two types of drugs for glaucoma will lower fluid production
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anhydrase inhibitors beta blockers
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With glaucoma treatment, what drugs increase fluid outflow?
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prostaglandin analogues parasympathomimetics
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name a carbonic anhydrase inhibitor that will decrease aqueous humor production
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Using them in combo does not increase resolution Just use topical! Topical: Dorzolamide brinzolamide
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side effects of oral carbonic anhydrase inhibitors such as metazolamide
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hypokalemia metabolic acidosis PU/PD
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This type of medical glaucoma tx can be used synergistically with carbonic anhydrase inhibitors BUT be careful in patients with cardiopulmonary disease
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beta blockers
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Prostaglandin analogues used for glaucoma will increase humor outflow BUT will also do this, this is contraindicated in pupillary block
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miosis (constrict pupil)
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what is the first line of defense in emergency glaucoma
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prostaglandin analogues (work in one hour)
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How do prostaglandin analogues lower IOP with glaucoma
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they increase the UNCONVENTIONAL outflow (know this)
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name a parasympathomimetic used to increase CONVENTIONAL outflow
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demecarium bromide
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Contraindications for parasympathomimetics
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they cause miosis- contraindicated in pupillary block
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How do hyperosmotics work for glaucoma medical tx
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Dehydrate the aqueous humor They also dehydrate the animal Used SHORT TERM only In emergency situation if refractory to other emergency meds
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name some hyperosmotics used vs glaucoma
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mannitol IV glycerin oral
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using hyperosmotics may exacerbate what other diseases?
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renal disease cardiopulmonary disease dehydration
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which drugs can be used prophylactically vs. glaucoma
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Beta blockers carbonic anhydrase inhibitor Demecarium bromide
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how often must you monitor an eye you are treating prophylactically for glaucoma (KNOW THIS)
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Every month for 3 months then every 3 month indefinitely
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why are topical anticholinergics contraindicated in glaucoma tx
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Dilate the pupil and cause crowding of the iridocorneal angle and exacerbate IOP elevation (KNOW THIS)
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Some surgeries for glaucoma tx increase outflow while others destroy part of the ciliary body, which should you do and how effective are they?
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Do them BOTH in combo. They are still blind in a year 50% of the time
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T or F: after glaucoma surgery the IOP will initially spike
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true (inflammation)
question
Term for surgery that decreases aqueous humor
answer
cyclophotocoagulation
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Term for surgery that increases aqueous outflow with glaucoma
answer
Gonioimplants (these fail due to fibrosis)
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What glaucoma surgical tx has the best prognosis (70% visual in a year, 53% in 3 years)?
answer
Diode endolaser therapy
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What are end stage therapies for glaucoma once the animal is irreversibly blind/painful and has increased IOP?
answer
enucleation evisceration with intraocular prosthesis ciliary body ablation with intravitreal injection (gentamycin or cidofovir)
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What client education will you offer with glaucoma
answer
It is incurable, progression is variable but it WILL progress (tx can slow) IOP will be painful, will eventually be blind If primary, the other eye will be affected Comfort is priority
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Layers of the posterior segment of the eye from outside in
answer
sclera choroid retina
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Layers of the retina
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pigmented epithelium (closest to choroid) rods/cones buller cells horizontal cells bipolar cells amacrine cells ganglion cells nerve layer fiber inner limiting membrane
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What connects the outer retina to the inner retina?
answer
Bipolar cells
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T or F: Horizontal and amacrine cells are not involved in vertical transmission of vision but contribute to the analysis of the image at the retainal level
answer
true
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Difference between direct ophthalmascope, panoptic (direct) and indirect
answer
Direct: great magnification so you only see a small part of the fundus. You also have to be close to the dogs face (caution) Panoptic- direct- does not magnify as much so you can see more fundus and easier screening for lesions INDIRECT- BEST way to screen retina for lesions It magnifies the least so you can see most of the fundus. Disadvantage- image is inverted and reversed!
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why ultrasound the fundus?
answer
We can try and determine retinal detachment Seagull shape Do this before cataract surgery because if the retina is detached the surgery will not cause vision!
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why does retinal detachment have a seagull shape?
answer
The retina is connected FIRMLY around the optic nerve but not that strong elsewhere so it makes a seagull shape
question
always evaluate these four components during a fundic exam
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tapetum optic disk/nerve head retinal blood vessels non tapetum
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atapetal animals are usually what, diurnal or nocturnal
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diurnal Lacking the tapetum Can be in animals that NORMALLY have tapetum (ex: dogs- especially albinos) Primates, squirrels, birds, pigs do not have tapetum- more pink fundus
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T or F: the tapetum is where the RPE lacks pigment
answer
true
question
who has a holangiotic retina?
answer
cat dog cow *retina gets blood supply from cilioretinal arteries- blood vessels all over
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Paurangiotic retina species? definition?
answer
horses! (elephant, rhino, marsupials) Blood vessels only near optic disk
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merangiotic retina who? what?
answer
rabbits blood vessels in a limited portion of the retina horizontally
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anangiotic retina who? what?
answer
birds, reptiles, bats Absence of vasculature in sensory retina The retina is much much thinner to allow passage of nutrients from choroid to retina
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Fundic exam: what is "pecten" and who has it?
answer
Birds- pecten- a bundle of blood vessels that sits RIGHT on top of the optic nerve so you cant even see the optic nerve. Speculation: provides nutrients to avascular retina and possible controls pH in the eye. Etc.
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what is conus papillaris and who has it?
answer
Reptile- conus papillaris- sits in the center of the optic nerve- probably the same function as the pectin of birds Not all reptiles have the conus papillaris and some have it young and then it degenerates
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What is the color of the tapetum in a dog
answer
<10 weeks: blue after 18 weeks: yellow
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T or F: In dogs the junction between tapetum and non tapetum is not well defined in most cases and just ventral to the optic nerve
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False, it IS just ventral to optic nerve but it is WELL defined However: In some cases there can be a undefined junction- tapetal "islands" normal variation
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what is Area centralis in a dog fundic exam
answer
an area lateral to the optic nerve- lacks blood vessels- HIGHEST concentration of photoreceptors and the area of BEST visual acuity.
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Nontapetal color in dogs depends on what?
answer
amount of melanin in RPE
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in which animal do optic nerve vessels cross the optic nerve head? in which animal do they go around
answer
dog- cross cat- they do not cross
question
What is a physiologic pit (fundic exam)
answer
Physiologic pit- a depression in the middle of the optic nerve DO NOT confuse with optic cupping which happens with glaucoma
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who has myelin in the optic disk (cat, dog) and who doesnt?
answer
dogs do- can make optic disk appear fuzzy cats don't so the canine optic disc can look irregular in margins but this would NOT be normal in a cat
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T or F: the cat has much less normal variation of the fundus
answer
true
question
what are stars of winslow?
answer
End on choroidal capillaries that look like dark dots throughout the tapetal fundus
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With progressive retinal atrophy, what is affected first?
answer
rods first (night blind) then cones
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T or F: progressive retinal atrophy is inherited
answer
true autosomal recessive
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fundic exam findings with progressive retinal atrophy
answer
hyperreflective tapetum in some cases the mutation also causes cataracts
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breeds affected by progressive retinal atrophy (PRA)
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poodle cocker more
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age of onset of progressive retinal atrophy (PRA)
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variable usually middle age
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clinical signs of progressive retinal atrophy (PRA)
answer
night blind reduced to absent PLR hyperreflective tapetum retinal vessel attenuation (starts at periphery- barely see vessels) optic nerve atrophy- pale then darker over time cataracts sometimes pigment clumping
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diagnosing progressive retinal atrophy (PRA)
answer
history, maze test ERG- useful early on blood test for mutation
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progressive retinal atrophy (PRA) tx
answer
do not breed no treatment screening genetics
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is progressive retinal atrophy (PRA) common or rare in cats?
answer
RARE Abyssinian, persian, siamese
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two forms of progressive retinal atrophy (PRA) in abyssinian cats
answer
1- rod-cone dysplasia 8-12 weeks old 2- rod-cone degeneration- older age onset and slower loss-starts at 2, blind by 6
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optic neuritis what is it? unilateral or bilateral?
answer
inflammation of the nerve- not a disease, it is a symptom usually bilateral!
question
signs of optic neuritis
answer
blind! nerve head hyperemia, hemorrhage OR the nerve head might be normal if only the retrobulbar nerve is affected!
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T or F: on fundic exam, If the components of the fundus are out of focus it tells you something is bulging forward
answer
true
question
Diagnosis of optic neuritis
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Fixed pupils and blind is suggestive with swollen optic nerve ERG is diagnostic! the ERG will be totally normal- the function of the retina is normal!
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causes of optic neuritis
answer
50% idiopathic! infection inflammation neoplasia trauma
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What is the end stage of optic neuritis?
answer
optic nerve atrophy KNOW THIS
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Treatment of optic neuritis
answer
treat underlying cause if you can ID systemic anti-inflammatories (aggressive)
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optic nerve atrophy is often secondary to what?
answer
Glaucoma PRA (progressive retinal atrophy) orbital disease optic neuritis
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What does the optic disc look like with optic nerve atrophy
answer
it appears grey-white in color and loses myelin (looks like a cat optic nerve head!)
question
What is SARDS
answer
sudden acquired retinal degeneration syndrome (SARDS)
question
signs of SARDS
answer
sudden vision loss (minimal vision may be there) over weeks/months variable PLR absence of lesions initially then retinal degeneration
question
Signalment of SARDS
answer
Middle aged, mildly obese females **Mini Schnauzers**
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Diagnosis of SARDS
answer
Extinguished ERG is diagnostic (no signal)
question
SARDS tx
answer
No good tx intravitreal injection with immunoglobulins
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T or F: chorioretinitis is a sign, not a disease
answer
true
question
causes of chorioretinitis in dogs
answer
distemper, fungi, autoimmune
question
causes of chorioretinitis in cats
answer
FIP FeLV toxoplasmosis fungi
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causes of chorioretinitis in horses
answer
uvetis (ERU)
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Inactive vs. active chorioretinitis
answer
Active- borders out of focus Inactive- sharp borders with chorioretinal scar
question
tx of chorioretinitis
answer
tx underlying cause symptomatic tx of inflammation
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What is a butterfly lesion and who gets it?
answer
Horse Used to be pathognomonic for equine recurrent uveitis It is NOT It can happen because of equine recurrent uveitis but can be from other causes as well
question
causes of retinal detachment
answer
trauma inflammation retinal/choroid/orbital neoplasia other
question
Where is the retinal attachment the weakest?
answer
between retina and RPE (it is strongest at the level of the optic nerve and the periphery)
question
types of retinal detachment
answer
non rhegmatogenous- no tear in retina rhegmatogenous- hole or tear in retina
question
hemorrhagic retinopathy is secondary to __________
answer
systemic hypertension coagulopathies systemic infections anemia? (only with thrombocytopenia)
question
hypertensive retinopathies Primary vs. secondary
answer
Primary <5% of cases secondary: renal failure, hyperthyroid, high salt diet, atherosclerosis, hypertrophic cardiomyopathy TAKE BLOOD PRESSURE
question
How is hypertensive retinopathy commonly presented? who gets it more?
answer
acute blindness with dilated unresponsive pupils. Can have retinal detachment Cats > dogs
question
Therapy for hypertensive retinopathy
answer
ID and treat cause Amlodipine**- calcium channel blocker** steroids if inflammation
question
tx of choice for hypertensive retinopathy. How does it work?
answer
Helps decrease systemic BP and also protects the retina directly (neuroprotective) Then add enalopril if needed
question
Enrofloxacin (baytril) is toxic in cats at what dose? what should you use instead?
answer
5mg/kg/day this is the recommended dose! causes retinal issues use pradofloxacin instead (a fluoroquinolone)
question
What will a mouth gag cause (wow, what an open ended question)
answer
can open the mouth too far and cause retinal ischemia and acute blindness
question
taurine deficiency in cats causes what?
answer
retinal degeneration and irreversible blindness
question
what is collie eye?
answer
congenital anomaly that causes bilateral asymmetric issues in the choroid, optic nerve and sclera of 30-85% of collies affected
question
ideal time to examine a collie for collie eye? Also, what ARE the signs of collie eye?
answer
7-8 weeks old the signs may be masked after that. Choroid hyperplasia possible coloboma, retinal detachment, retinal/vitreal hemorrhages blind if severe
question
What does congenital retinal dysplasia look like?
answer
Jumbling of the layers of the retina with rosette formation nonprogressive, can be confused with retinal folds or degeneration
question
breeds predisposed for retinal dysplasia?
answer
spaniels labs goldens GSD
question
What is the total horizontal visual field in horses? what about binocular field?
answer
total 350 binocular 60
question
can horses see color?
answer
dichromatic vision (two color)
question
in horses, when should you perform a fluorescein dye exam?
answer
for EVERY horse exam!!!!
question
in horses how can you test patency of the nasolacrimal system?
answer
Jones test retrograde flushing normograde flushing
question
Normal IOP of a horse? if low this means what? if high?
answer
normal 15-30 mm Hg low = uveitis high = glaucoma
question
name the four periocular nerve blocks in horses. Also state whether it is sensory or motor or both
answer
Auriculopalpebral- motor (For exam) Frontal/supraorbital- BOTH Infratrochlear- sensory Lacrimal- sensory Zygomatic- sensory
question
for a frontal block in horses, where do you go?
answer
supraorbital foramen
question
for a infratrochlear sensory nerve block, where do you go?
answer
trochlear notch
question
most common equine eye tumor?
answer
squamous cell carcinoma
question
locations of squamous cell carcinoma in horses?
answer
Eyelids 3rd eyelid conjunctiva limbus
question
Scc tx in horses- what is the goal?
answer
destroy the tumor while maintaining sight and preserving cosmetics
question
T or F: with SCC treatment in horses they often need it for life and you should re-evaluate every 3 months
answer
FALSE everything is true but re-evaluate every SIX months
question
Where does ocular SCC in horses metastasize (remember that it is also locally invasive)
answer
LN salivary gland thorax
question
What ocular SCC presentation has the highest recurrence rate in horses?
answer
eyelid or third eyelid
question
SCC prevention in horses
answer
UV protection eyelid tattooing?
question
are corneal ulcers common or rare in horses?
answer
common (remember that you were supposed to do a fluorescein dye exam in EVERY horse exam) they are usually from trauma
question
how would your diagnostics change for dealing with horses with corneal ulcers IF you suspect infection, melting or stromal defects?
answer
you would culture you would do cytology to look for bacteria, neutrophils or hyphae
question
medical tx for a simple ulcer in horses
answer
topical antibiotics atropine- relieves pain, mydriatic systemic anti-inflammatory (flunixin, phenylbutazone)
question
when giving atropine for ulcer tx in horses you should monitor for this side effect
answer
colic
question
If a horse simple ulcer is not healing after _______ days of therapy you should modify diagnosis or change your plan
answer
3-5 days
question
Complicated corneal ulcers in horses get infected with what bacteria? fungi?
answer
staph strep pseudomonas aspergillus fusarium
question
what causes an ulcer to become a complicated melting ulcer?
answer
endogenous and microbial proteinases
question
What depth of a horse cornea ulcer is considered "deep" or severe
answer
50% of the stroma
question
Horses get pissed about fluid eye drops eventually so what is a better approach to long term tx?
answer
subpalpebral lavage line sutured in and weaved into mane with 20 gauge catheter
question
tx of complicated ulcers in horses?
answer
topical antibiotics oral NSAIDs Atropine
question
What topical antibiotics are used on complicated ulcers in horses?
answer
Ofloxacin Cefazolin
question
what topical antifungal is commonly used QID for complicated ulcers in horses
answer
voriconazole 1% also itraconazole
question
What systemic antifungal is commonly used for complicated ulcers in horses?
answer
fluconazole
question
what is a good antiproteinase/anticollagenase agent given every 1-2 hours vs. complicated ulcers in horses?
answer
serum/plasma
question
surgery for complicated ulcers in horses
answer
keratectomy or debridement conjunctival graft corneoconjunctival transposition corneal or amniotic membrane transplant
question
are corneal stromal abscesses in horses fluorescein positive or negative
answer
negative! BUT you should see corneal vascularization and edema
question
what should you NEVER use on corneal stromal abscesses?
answer
steroids because you MUST differentiate from primary uveitis
question
medical tx of corneal stromal abscesses
answer
antimicrobials reflex uveitis tx (atropine, banamine) subpalpebral lavage line to give meds
question
surgical tx for corneal stromal abscesses
answer
conjunctival graft corneoconjunctival transposition penetrating keratoplasty/corneal transplant deep lamellar endothelial keratoplasty intracorneal injections?
question
what is the most common cause of equine blindness
answer
uveitis
question
causes of equine uveitis?
answer
many infectious trauma neoplastic idiopathic immune mediated
question
KNOW these signs of uveitis in horses
answer
blepharospasm epiphora photophobia conjunctival hyperemia aqueous flare miosis
question
Diagnosis of equine uveitis?
answer
rule out primary disease CBC/Chhem serology for lepto
question
tx of uveitis in horses?
answer
address underlying cause treat aggressively then taper off treat TWO weeks past resolution
question
main points of uveitis medical tx
answer
steroid- dexamethasone atropine systemic NSAID- flunixin possibly systemic antibiotics
question
what steroid should not be used for equine uveitis because it can't penetrate the cornea
answer
hydrocortisone
question
if you are going to use steroids (dex) for uveitis in horses what do you need to do first?
answer
fluorescein stain to be SURE there are no ulcers
question
what is "moon blindness" or "periodic ophthalmia" in 8-25% of horses
answer
equine recurrent uveitis
question
it is considered equine recurrent uveitis after how many treatments and returns of the condition
answer
2
question
stages of equine recurrent uveitis
answer
acute disease- pain inflammation (most common) insidious- no pain, low grade inflammation- more in appaloosas and drafts Chronic end stage- blinding deformity
question
signs of chronic end stage equine recurrent uveitis
answer
phthisis bulbi pupillary occlusion dense cataract luxated lens detached retina
question
other complicating issues/changes with equine recurrent uveitis?
answer
calcified band keratopathy blinding cataract vitreal floaters (or fibrinous traction bands) retinal detachments secondary glaucoma
question
equine recurrent uveitis tx
answer
topical AND SYSTEMIC tx
question
surgical tx for equine recurrent uveitis
answer
suprachoroidal cyclosporine implant POOR prognosis overall
