Neuroophthalmo

Question 1

Evaluation of PLR in birds.

Answer 1

Birds’ pupillary light response can be potentially controlled due to striated muscles in their iris (intermittent dynamic anisocoria).
Complete decussation of optic nerve fibres result in the absence of the consensual pupillary response, but false indirect PLR can be elicited when the light is shone through their thin orbital septum.

Question 2

Palpebral reflex- afferent and efferent arms

Answer 2

Afferent= V cranial nerve
Efferent= VII facial nerve

Question 3

What is amblyopia and what are the main causes of it?

Answer 3

Amblyopia (in humans ‘lazy eye’) is loss of vision in otherwise normal eye when the brain does not receive adequate informations from one eye and is not able to form proper binocular vision. The causes of amblyopia are: misalignement of the eyes (strabismus); different refractive errors in two eyes (refractive amblyopia) or congenital opacities in one of the eyes (deprivation amblyopia).

Question 4

VBO vestibuloocular reflex

Answer 4

Assessment of extraocular muscle and vestibular system.
Its role is to stabilize the images on the retinas during movement of the head by producing eye movement in the direction opposite to head movement thus preserving the image on the central visual fields.

Question 5

Testing VBO

Answer 5

rapid movement of the head and elicit eye movement

caloric reflex test (humans)

Question 6

Corneal reflex

Answer 6

corneal sensation- afferent way: trigeminal nerve

efferent way: facial nerve

Question 7

Lagophthalmos

Answer 7

incomplete eyelid closure

Question 8

What is strabismus and why it may cause vision problems in young puppies?

Answer 8

Strabismus is abnormal eye position, ‘misalignment’. Can be unilateral, bilateral; converging/diverging upward/downward (hypotropia/hypertropia). Congenital strabismus or strabismus that developed in early age ‘puppiness’ during formation of bilateral vision may cause amblyopia (lazy eye) when the images derived from both eyes are not compatible and brain favours one eye causing functional blindness in the affected eye.

Question 9

How do we call:

converging strabismus
diverging strabnismus
upward strabismus
downward strabismus

Answer 9

esotropia
exotropia
hypertropia
hypotropia

Question 10

What is ESOTROPIA?

Answer 10

strabismus convergens

Question 11

What is Exotropia?

Answer 11

strabismus divergens

Question 12

What is HYPERTROPIA?

Answer 12

strabismus upwards

Question 13

What is HYPOTROPIA?

Answer 13

strabismus downwards

Question 14

2 main functions of the cornea

Answer 14

1. Protection

2. Vision 70 % of the light is refracted on the cornea.