Ear and eye

Question 1

External ear and external acoustic meatus - main issues

Answer 1

◼ Inflammation
◼ Hyperplasia > due to inflammation, can block meatus
◼ Neoplasia

Question 2

Otitis externa - what is this

Answer 2

◼ Inflammation of
external acoustic
meatus

Question 3

Otitis media - what is this?

Answer 3

◼ Inflammation of middle ear
◼ Inflamed mucoperiosteum

Question 4

Middle ear: - includes what structures? species differences?

Answer 4

◼ Ossicles
◼ Bulla
<><><><>
Bulla types:
o Cavitary
◼ Dog
◼ Cat (complete membranous septum)
◼ Sheep
◼ Horse (very small)
o Septate
◼ bovid

Question 5

Otitis media origins

Answer 5

Descending infection (external auditory meatus)
◼ From otitis externa
<><>
Systemic/haematogenous infection
◼ Mycoplasma bovis
◼ Histophilus somni
<><>
Ascending infection (auditory tube) > up from pharynx
◼ Trueperella pyogenes
◼ Pasteurella multicida

Question 6

Other middle ear diseases that are not otitis media

Answer 6

Aural (nasopharyngeal) polyp
◼ Cat
◼ Ciliated epithelium
<><>
Tympanokeratoma
◼ Previously called epidermoid inclusion cyst and aural cholesteatoma
◼ Squamous metaplasia
◼ Dog, horse
◼ Keratin debris
◼ Cholesterol
<><>
Neoplasia
◼ SCC
◼ adenocarcinoma

Question 7

Auditory tube and guttural pouch - issues in the horse

Answer 7

◼ Salpinx therefore salpingitis
<><><><>
◼ Guttural tympany
◼ Empyema
◼ Aspergillus > Carotid hemorrhage

Question 8

eye anatomic structures

Answer 8

◼ Globe (bulbi)
◼ Optic nerve
<><>
Accessory structures (adnexa):
◼ Eyelids
◼ Lacrimal apparatus (sac and duct)
◼ Orbital fascia
◼ Extraorbital muscles

Question 9

Size of Eyeball - small vs large

Answer 9

Small
◼ Microphthalmia (congenital)
◼ Phthisis bulbi (acquired) > Phthisis = ‘Tie sus’
> something catastrophic happenned, and the whole thing shrunk… fibrosis
<><>
Large
◼ Buphthalmus
> Glaucoma, almost always

Question 10

Normal eye – aqueous humor production and movement

Answer 10

• 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
  <><><><>
• horse is different

Question 11

components of the Iridocorneal (filtration) angle

Answer 11

◼ Pectinate ligaments
◼ Trabecular meshwork
◼ Corneoscleral meshwork
◼ Scleral vasculature

Question 12

consequences of glaucoma
- on retina, uvea, and cornea

Answer 12

Buphthalmus
<><>
Retina
◼ Atrophy
◼ Cupping of disc
◼ Wallerian degeneration of optic nerve
<><>
Uvea
◼ Retraction and collapse of filtration angle
<><>
Cornea
◼ Edema (corneal endothelium loss)
◼ Stria (breaks in Descemet’s)
◼ Exposure keratitis

Question 13

Glaucoma causes

Answer 13

◼ Increased production of fluid
◼ Altered flow at pupil
◼ Reduced outflow > This is most common

Question 14

Glaucoma: Increased fluid production - when might we see this?

Answer 14

◼ Inflammation > Anterior uveitis
◼ Neoplasia
◼ Hypertension

Question 15

Glaucoma: Altered flow at pupil - when might we see this?

Answer 15

◼ Anterior synechia
> iris sticks to something that it shouldnt - cornea
<><>
◼ Posterior synechia (to lens) and iris bombe (bulging)

Question 16

Glaucoma: Obstructed outflow - primary cause? most common secondary cause?

Answer 16

Primary glaucoma
◼ Congenital - goniodysgenesis
<><><><>
Secondary glaucoma > more common
◼ Preiridial fibrovascular membrane (PIFM) > granulation tissue

Question 17

Glaucoma: Obstructed outflow;
Preiridial fibrovascular membrane
- etiology?
- related membrane?

Answer 17

1. 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
2. retinal detachment can be traumatic or spontaneous - damaged retina produces VEGF, > PIFM
3. Ciliary body tumors produce VEGF
   > grow behind the iris, cant see them
   <><><><>
   Cytokines – VEGF (vascular endothelial growth factor)
   ◼ Uveitis
   ◼ Retinal detachment
   ◼ Ciliary body tumor
   <><><><><><><><>
   <><><><><><><><>
   Related membrane – Retrocorneal fibrovascular membrane
   ◼ Similar to PIFM but on Descemets membrane

Question 18

Glaucoma: Obstructed outflow causes

Answer 18

◼ 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

Question 19

Keratitis definition?
causes?

Answer 19

inflammation of cornea
<><><><>
◼ Pink eye
◼ Infectious keratoconjunctivitis
> Moraxella bovis
> Feline herpesvirus
=> Corneal sequestrum

Question 20

Ulceration of cornea pathogenesis

Answer 20

◼ Tears
◼ Epithelial sliding and regeneration
◼ Vascularization
◼ Pigmentation
◼ Descemetocele – bulging of Descemet’s membrane
◼ Iris prolapse
<><><><>
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

Question 21

eye neoplasms - which are common

Answer 21

• 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

Question 22

Uvea - what is this? parts?

Answer 22

• Vascular tunic
  <><><><>
  ◼ Anterior uvea (iris and ciliary body)
  ◼ Posterior uvea (choroid)
  ◼ Blood eye barrier – endothelial cells of iridial vessels

Question 23

Uveal inflammation terms

Answer 23

◼ Iritis - iris
◼ Cyclitis– ciliary body
◼ Anterior uveitis - anterior segment - iridocyclitis
◼ Choroiditis - choroid
◼ Panuveitis– choroid, ciliary body, iris
◼ Ophthalmitis– all parts of eye

Question 24

Uveal inflammation - types

Answer 24

◼ Suppurative – bacteria, FIP
<><>
◼ Lymphocytic plasmacytic
> Idiopathic in cats
> Malignant Catarrhal Fever
<><>
◼ Granulomatous
> fungi, yeast
> esp blasto in dogs
<><>
◼ Lens induced
> Phacolytic– lens protein leaks out of capsule
> Phacoclastic– lens ruptures

Question 25

Uveal neoplasia

Answer 25

◼ Anterior uveal melanoma > infiltrate through sclera and metastasize
> Diffuse iris melanoma of cats
> Iris melanoma of dogs
<><>
◼ Ciliary body tumor (glaucoma)
<><>
◼ Ocular posttraumatic tumor of cats
> Called sarcoma but from lens epithelium.
> related to phacoclastic uveitis in cats