Ear and eye Flashcards
External ear and external acoustic meatus - main issues
◼ Inflammation
◼ Hyperplasia > due to inflammation, can block meatus
◼ Neoplasia
Otitis externa - what is this
◼ Inflammation of
external acoustic
meatus
Otitis media - what is this?
◼ Inflammation of middle ear
◼ Inflamed mucoperiosteum
Middle ear: - includes what structures? species differences?
◼ Ossicles
◼ Bulla
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Bulla types:
o Cavitary
◼ Dog
◼ Cat (complete membranous septum)
◼ Sheep
◼ Horse (very small)
o Septate
◼ bovid
Otitis media origins
Descending infection (external auditory meatus)
◼ From otitis externa
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Systemic/haematogenous infection
◼ Mycoplasma bovis
◼ Histophilus somni
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Ascending infection (auditory tube) > up from pharynx
◼ Trueperella pyogenes
◼ Pasteurella multicida
Other middle ear diseases that are not otitis media
Aural (nasopharyngeal) polyp
◼ Cat
◼ Ciliated epithelium
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Tympanokeratoma
◼ Previously called epidermoid inclusion cyst and aural cholesteatoma
◼ Squamous metaplasia
◼ Dog, horse
◼ Keratin debris
◼ Cholesterol
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Neoplasia
◼ SCC
◼ adenocarcinoma
Auditory tube and guttural pouch - issues in the horse
◼ Salpinx therefore salpingitis
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◼ Guttural tympany
◼ Empyema
◼ Aspergillus > Carotid hemorrhage
eye anatomic structures
◼ Globe (bulbi)
◼ Optic nerve
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Accessory structures (adnexa):
◼ Eyelids
◼ Lacrimal apparatus (sac and duct)
◼ Orbital fascia
◼ Extraorbital muscles
Size of Eyeball - small vs large
Small
◼ Microphthalmia (congenital)
◼ Phthisis bulbi (acquired) > Phthisis = ‘Tie sus’
> something catastrophic happenned, and the whole thing shrunk… fibrosis
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Large
◼ Buphthalmus
> Glaucoma, almost always
Normal eye – aqueous humor production and movement
- produced by epithelial tissue of ciliary body
> moves through posterior chamber, through pupil, into anterior chamber, absorbed at angle of iris and the cornea (iridocorneal angle)
◼ Ciliary body (production)
◼ Posterior chamber
◼ Pupil
◼ Anterior chamber
◼ Iridocorneal (filtration) angle
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components of the Iridocorneal (filtration) angle
◼ Pectinate ligaments
◼ Trabecular meshwork
◼ Corneoscleral meshwork
◼ Scleral vasculature
consequences of glaucoma
- on retina, uvea, and cornea
Buphthalmus
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Retina
◼ Atrophy
◼ Cupping of disc
◼ Wallerian degeneration of optic nerve
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Uvea
◼ Retraction and collapse of filtration angle
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Cornea
◼ Edema (corneal endothelium loss)
◼ Stria (breaks in Descemet’s)
◼ Exposure keratitis
Glaucoma causes
◼ Increased production of fluid
◼ Altered flow at pupil
◼ Reduced outflow > This is most common
Glaucoma: Increased fluid production - when might we see this?
◼ Inflammation > Anterior uveitis
◼ Neoplasia
◼ Hypertension
Glaucoma: Altered flow at pupil - when might we see this?
◼ Anterior synechia
> iris sticks to something that it shouldnt - cornea
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◼ Posterior synechia (to lens) and iris bombe (bulging)
Glaucoma: Obstructed outflow - primary cause? most common secondary cause?
Primary glaucoma
◼ Congenital - goniodysgenesis
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Secondary glaucoma > more common
◼ Preiridial fibrovascular membrane (PIFM) > granulation tissue
Glaucoma: Obstructed outflow;
Preiridial fibrovascular membrane
- etiology?
- related membrane?
- uveitis causes the release of VEGF, which causes PIFM to develop > glaucoma
- granulation tissue grows over filtration angle and blocks it
> also produces edema and sometimes hemorrhage, which also can block filtration angle - retinal detachment can be traumatic or spontaneous - damaged retina produces VEGF, > PIFM
- Ciliary body tumors produce VEGF
> grow behind the iris, cant see them
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Cytokines – VEGF (vascular endothelial growth factor)
◼ Uveitis
◼ Retinal detachment
◼ Ciliary body tumor
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Related membrane – Retrocorneal fibrovascular membrane
◼ Similar to PIFM but on Descemets membrane
Glaucoma: Obstructed outflow causes
◼ Preiridial fibrovascular membrane
◼ Hyphema > (hemorrhage) blood in the anterior chamber: from trauma, coagulation disorders, PIFM…
◼ Exudates > plasmoid aqueous > aqueous becomes more protinaceous, like plasma
◼ Neoplasia
◼ Lens luxation > can be hereditary, or trauamtic > dislocated lens pushes on iris from behind
Keratitis definition?
causes?
inflammation of cornea
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◼ Pink eye
◼ Infectious keratoconjunctivitis
> Moraxella bovis
> Feline herpesvirus
=> Corneal sequestrum
Ulceration of cornea pathogenesis
◼ Tears
◼ Epithelial sliding and regeneration
◼ Vascularization
◼ Pigmentation
◼ Descemetocele – bulging of Descemet’s membrane
◼ Iris prolapse
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epithelium gets nutrition from the tears
- lack of tears = dry, exposure keratitis
- sliding of epithelium on periphery towards the area of lost cells
> happens within minutes of corneal injury
> within a matter of days, will seal ulcer
- if things take longer, and keratitis is severe, then blood vessels will grow into cornea from eriphery (1mm per day) > we see these with ophthalmoscope
> melanocytes can move in also and cause pigmentation
> if the ulcer affects some of the collagen under epithelium, inner basement membrane (posterior corneal) will bulge outward > desmetocele > iris sticks to this bulge, can prolapse through small hole
eye neoplasms - which are common
- squamous cell carcinoma in cattle - junction of sclera and cornea
<><> - limbal melanoma in dogs
> black mass developing on globe and the junction between the cornea and sclera > most likley a limbal melanoma > this is benign, and in the early stage can be removed with a superficial keratectomy (do not need to perform an ablation for this tumor)
> peel it off in layers until its gone! refer to opthalmologist… - if you leave it too long, can no longer use the superficial keratectomy to get rid of it
Uvea - what is this? parts?
- Vascular tunic
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◼ Anterior uvea (iris and ciliary body)
◼ Posterior uvea (choroid)
◼ Blood eye barrier – endothelial cells of iridial vessels
Uveal inflammation terms
◼ Iritis - iris
◼ Cyclitis– ciliary body
◼ Anterior uveitis - anterior segment - iridocyclitis
◼ Choroiditis - choroid
◼ Panuveitis– choroid, ciliary body, iris
◼ Ophthalmitis– all parts of eye
Uveal inflammation - types
◼ Suppurative – bacteria, FIP
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◼ Lymphocytic plasmacytic
> Idiopathic in cats
> Malignant Catarrhal Fever
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◼ Granulomatous
> fungi, yeast
> esp blasto in dogs
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◼ Lens induced
> Phacolytic– lens protein leaks out of capsule
> Phacoclastic– lens ruptures
Uveal neoplasia
◼ Anterior uveal melanoma > infiltrate through sclera and metastasize
> Diffuse iris melanoma of cats
> Iris melanoma of dogs
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◼ Ciliary body tumor (glaucoma)
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◼ Ocular posttraumatic tumor of cats
> Called sarcoma but from lens epithelium.
> related to phacoclastic uveitis in cats
