Abnormal size & Position of the eye

Question 1

problems with The Orbit and Space Occupying Lesions

Answer 1

 Infection/infl (abscess/cellulitis)
Neoplasia (usually malignant)
Specific tissue infl

Question 2

globe displacement clinical signs

Answer 2

often dorsolaterally

freq anterior component - Exophthalmos

Question 3

why does the 3rd eyelid protrude with exophthalmos

Answer 3

mass displaces orbital fat which pushes on the 3rd eyelid

Question 4

what is microphthalmia

Answer 4

small eye from birth
usually bilateral
may have other defects

Question 5

cause of microphthalmia

Answer 5

destruction of ciliary body (cyclodestruction)
sequela to infl, pthisis bulbi (severe uveitis)
targeted surgical destruction
chemical ablation

Question 6

what is buphthalmia

Answer 6

enlargement of the eye

Question 7

buphthalmia is due to…

Answer 7

incr in IOP - glaucoma

Question 8

buphthalmia - pathogenesis

Answer 8

incr IOP causes globe stretching + other changes

Question 9

buphthalmia - effects on the eye

Answer 9

conjunctival + episcleral vessel hyperaemia
corneal oedema (endothelial damage)
Haabs strike (breaks in descemets membrane)
zonular tears
corneal ulceration - d/t corneal overexposure

Question 10

zonular tears

Answer 10

over stretching of fibres d/t lens displacement

visible lens equator through pupil

Question 11

glaucoma

Answer 11

incr IOP

damage to the optic nerve head + neural retina

Question 12

the retina has how many layers

Answer 12

10 - 1 epithelial + 9 neural (rod + cones etc)

Question 13

primary glaucoma

Answer 13

inherited - affects both eyes, don’t breed the animal

goniodysgenesis - abnormal iridocorneal angle (ICA)

Question 14

2 forms of primary glaucoma + which affects dogs more

Answer 14

open + closed
closed is more common in dogs (rapid onset)
open more in humans (insidious onset)

Question 15

secondary glaucoma

Answer 15

something affecting the ICA

Question 16

causes of secondary glaucoma

Answer 16

blood, fibrin, PFIMs, WBCs, neoplasia
infl
hyphema
lens luxation
intraocular/metastatic neoplasia
trauma

Question 17

causes of feline glaucomas

Answer 17

can be primary

mostly secondary with uveitis - FIV, FeLV, FIP + toxoplasma, idiopathic

Question 18

why consider the other, non affected eye in glaucoma

Answer 18

primary glaucoma will affect both eyes

long term monitoring of other eye is needed

Question 19

glaucoma - clinical signs with mid to high IOP

Answer 19

mid-dilated non-responsive pupil
conjunctival + episcleral vess conjugation
+/- vision problems

Question 20

glaucoma - clinical signs with high to v.high IOP

Answer 20

corneal oedema
haabs striae
cupping of optic nerve head
lens displacement
aphakic crescent

Question 21

aphakic crescent

Answer 21

tear of the zonules + lens movement away from it
development of crescent between pupil + lens
(corneal ulceration)

Question 22

glaucoma - treatment

Answer 22

control IOP - antihypertensive drops

if secondary - remove cause

Question 23

phacodonesis

Answer 23

vibration on the lens

Question 24

iridonesis

Answer 24

movement of the iris

Question 25

when does phacodonesis + iridonesis often happen

Answer 25

often in early stage of subluxation

Question 26

posterior luxation

Answer 26

lens falls backwards into the eye
cataract formation
lens induced uveitis
lens adheres to the retina

Question 27

anterior luxation

Answer 27

lens moves forward into the anterior chamber

rare

Question 28

anterior luxation - potential problem

Answer 28

pupil block glaucoma
corneal endothelial damage
damage to centre of the cornea

Question 29

clinical signs of subluxation/luxation

Answer 29

iridonesis-phacodonesis
deep anterior chamber
anterior presentation of the luxation
incr IOP

Question 30

what damage does rapid + high incr in IOP do

Answer 30

retinal ganglion cell
optic nerve head
(blood vessels)

Question 31

main cause of rapid + high incr in IOP

Answer 31

pupil block glaucoma

Question 32

treatment of pupil block glaucoma

Answer 32

immediate removal of the lens

medical therapy to control future IOP spikes

Question 33

surgical management of lens luxation

Answer 33

remove lens prior to anterior luxation
remove lens if acutely luxated anteriorly
control of IOP with drugs