The Abnormal Pupil

Question 1

What is iris coloboma ?

Answer 1

Abnormal development of the iris which leaves a hole

Typically ventral but can be atypical

Question 2

When should the pupillary membranes have regressed by?

Answer 2

14 days when the eyes open

Question 3

What is a uveal cyst?

Answer 3

Spherical cysts formed from the uveal epithelium

Usually free floating in the anterior chamber

Can burst and leave pigment on the corneal endothelium

Question 4

What is iris atrophy?

Answer 4

Iris tissue thins as the animal ages and can even disappear leaving a ragged pupil margin

Question 5

What is posterior synechia?

What can it lead to

Answer 5

With uveitis the iris can become sticky

Adheres to the anterior lens capsule

Decreased or absent PLR, glaucoma if adhesion in 360 degrees

Question 6

What is iris melanoma ?

Answer 6

Darkening of the iris

Can be benign melanosis or neoplastic change e.g. iris melanoma

Can change the shape of the pupil, reduce PLR and cause glaucoma

Question 7

What does SARDS stand for?

How does it present?

Answer 7

Sudden Acquired Retinal Degeneration Syndrome

-acute onset blindness without other opthalmic or neurological abnormalities

Sudden degeneration of photoreceptors of acute origin - PLR absent with RED light bur present with BLUE

Question 8

What is PRA?

What CS?

Answer 8

Inherited disease
Photoreceptors degenerate rods first

Night blindness -> complete blindness

Tapetal hyperreflectivity and blood vessel attenuation

Question 9

What is optic nerve head coloboma?

Answer 9

Congenital malformation of the optic n

Causes blindness from birth

Question 10

What is optic neuritis?

Answer 10

Inflammation of the optic n

Blindness or reduced vision if early

Optic nerve head pink and haemorrhagic
Can be peripheral oedema and retinal detachment

Question 11

What can cause miosis?

Answer 11

Uveitis

Horner’s

Question 12

Describe the clinical signs associated with anterior uveitis

Answer 12

miosis
Aqueous flare
Conjunctival hyperaemia
If severe: hypopion and hyphaema

Question 13

What causes mydriasis?

Answer 13

Glaucoma
Dysautonomia
Fear/stress
Central blindness

Question 14

What is dysautonomia?

What are the Clinical signs

Answer 14

Dysregulation of ANS

Third eyelid protrusion 
Decreased tear production 
MYDRIASIS 
Mega oesophagus 
Megacolon 
Atonic bladder

Question 15

Describe the findings at rest, for direct PLR, and indirect PLR for:

• a pre chiasmatic lesion on the right

Answer 15

Pupil at rest 
L- normal
R- dilated 
Direct PLR 
L- present 
R- absent 
Indirect PLR 
L- absent 
R- present

Question 16

Describe the findings at rest, for direct PLR, and indirect PLR for:

• A focal optic tract lesion

Answer 16

Pupil at rest 
L-normal 
R-  Normal
Direct PLR 
L- present 
R- present 
Indirect PLR 
L- present 
R-  present

Question 17

Describe the findings at rest, for direct PLR, and indirect PLR for:

• a chiasmal lesion

Answer 17

Pupil at rest 
L- dilated 
R- dilated 
Direct PLR 
L- absent 
R- absent 
Indirect PLR 
L- absent 
R- absent

Question 18

Describe the findings at rest, for direct PLR, and indirect PLR for:

-oculomotor nerve lesion left

Answer 18

Pupil at rest 
L-dilated  
R-  normal 
Direct PLR 
L- absent 
R-  present 
Indirect PLR 
L- absent 
R- present

Question 19

Describe the findings at rest, for direct PLR, and indirect PLR for:

• Parasympathetic nucleus of CN3 lesion (right)

Answer 19

Pupil at rest 
L- normal size 
R- dilated  
Direct PLR 
L- present 
R- absent 
Indirect PLR 
L- Present 
R- absent