Abnormal pupil

Question 1

What are the 2 systems that can cause an abnormal pupil?

Answer 1

opthalmic
neuro

Question 2

What are the 4 ophthalmic locations causing abnormal pupils?

Answer 2

iris
lens
retina
miosis/mydriasis

Question 3

What are the 2 neuro signs causing abnormal pupil?

Answer 3

miosis/mydriasis
visual/plr pathways

Question 4

What si Iris coloboma?

Answer 4

abnormal development of the iris leaving a defect or hole in the iris

Question 5

What is a peristent pupillary membrane?

Answer 5

delayed regression of fetal vascular tissue
iris to iris, iris to lens, iris to cornea
can cause abnormal pupil

Question 6

What is a uveal cyst?

Answer 6

spherical cysts formed from uveal epithelium, usually free floating in anterior chamber
can burst and leave pigment on corneal endothelium
abnormal pupil

Question 7

What is iris atrophy?

Answer 7

with age, iris tissue can become thin and dissapear = ragged pupil margin

Question 8

What is posterior synechia?

Answer 8

with uveitis the iris can become sticky and adhere to the anterior lens capsule causing dyscoria, decreased/absent PLR, glaucoma

Question 9

What is iris melanosis/melanoma?

Answer 9

darkening of iris, benign melanosis or malignant melanoma
can cause change in pupil shape, decreased PLR and glaucoma

Question 10

How does anterior lens luxation change pupil shape?

Answer 10

anterior displacement of the lens can alter the pupil shape and means that pupil doesn’t constrict and dilate as normal

Question 11

What is sudden acquired retinal degeneration syndrome SARDS?

Answer 11

presents as sudden onset blindness (1-2w hx)
represents sudden degeneration of the photoreceptors
no ophthalmic or neuro abnormalities (other than absent menace and plr)
fundus appears normal, electroretinogram testing reveals flat line

Question 12

What is progressive retinal atrophy PRA?

Answer 12

inherited dz
photoreceptors degenerate
causes initial cCS of night blindness followed by full
fundoscopy reveals tapetal hyperreflectivity and blood vessel attenuation (atrophy)

Question 13

What is optic nerve head hypoplasia/coloboma?

Answer 13

congenital malformation of optic nerve causing eye to be blind from birth
pre-chiasmal lesion

Question 14

What is optic neuritis?

Answer 14

inflammation of optic nerve
manifests as blindness or reduced vision
optic nerve head is pink/haemorrhagic, swollen, can be peripapillary oedema/retinal detachment

Question 15

What are the four signs of horner’s?

Answer 15

miosis
enophthalmos
third eyelid protrusion
ptosis

Question 16

What are the causes of miosis that can affect pupil shape?

Answer 16

uveitis
horner’s

Question 17

What are the causes of mydriasis affecting pupil shape?

Answer 17

glaucoma
dysautonomia
fear
central blindness

Question 18

What is dysautonomia?

Answer 18

deregulation of autonomic nervous system
causes 3rd eyelid protrusion, decreased tear production, mydriasis, megaoesophagus, megacolon, atonic bladder

Question 19

Why can fear cause mydriasis?

Answer 19

when stressed: hightened sympathetic stimulation = mydriasis that is not very responsive to bright light = reduced/absent plr

Question 20

What is the optic chiasm?

Answer 20

Where the optic nerves of both eyes meet

Question 21

What are the signs of a pre-chiasmal lesion of one side?

Answer 21

dilated pupil, absent direct plr and present indirect plr of the affected side

normal pupil, present direct plr, absent indirect plr of non-affected side

Question 22

What are the signs of a chiasmal lesion?

Answer 22

pupils dilated at rest, bilateral absent direct plr, bilateral absent indirect plr

Question 23

What are the signs of a focal optic tract lesion of one side?

Answer 23

both pupils will be normal size at rest, direct and indirect plrs present

Question 24

What are the signs of an oculomotor nerve lesion of one side?

Answer 24

dilated pupil at rest of affected side
absent direct and indirect plr of affected side

Question 25

What are the signs of a parasympathetic nucleus of CN3 lesion on one side?

Answer 25

dilated pupil at rest of affected side
absent direct and indirect plr of affected side

Question 26

What tests would you perform on ophthalmic examination of a 1day hx of sudden onset blindness in a 5yo dog?

Answer 26

menace
plr direct and indirect
palpebral
distant direct ophthalmoscopy
examination with lights
funduscopy

Question 27

If electroretinography shows a flatline in a sudden onset blindness dog what is it likely to be?

Answer 27

SARDS

Question 28

What 3 things do we talk about when describing the retina?

Answer 28

tapetal reflectivity
retinal vasculature
optic nerve head

Question 29

What happens to the retina structurally when there is hyperreflectivity?

Answer 29

retina is thinner than usual

can happen in progressive retinal atrophy (PRA)