Introduction

Question 1

Characteristics of eyes of predator species

Answer 1

1- Carnivore
2- Frontal globe position
3- Greater binocular vision
4- Open bony orbit: the ramus of mandible imposes on the orbital area when the mouth is opened; cellulitis in this area is quite painful when opening the mouth.

Question 2

Characteristics of eyes of prey speices

Answer 2

1- Herbivore
2- Lateral globe position
3- Greater peripheral vision
4- Closed bony orbit: more protection for the eye

Question 3

Clinically important characteristics of orbital anatomy of predator species

Answer 3

Open bony orbit: the ramus of mandible imposes on the orbital area when the mouth is opened; cellulitis in this area is quite painful when opening the mouth.

Question 4

Lashes (cilia) of dogs and cats

Answer 4

dogs have 2-4 rows of upper lashes; cats have no true lashes

Question 5

Lashes (cilia) of rabbits

Answer 5

rabbits have upper and lower lashes

Question 6

Pupil shape

Answer 6

canine = round; domestic feline = vertical; herbivore = horizontal

Question 7

What holds the third eyelid in place?

Answer 7

It is generally retracted and held in place by sympathetic tone.

Question 8

Species that lack a tapetum

Answer 8

Occasionally cats and horses lack a tapetum. The tapetal color is loosely associated with coat color. The pig, camelids, red kangaroo and birds do not have a tapetum.

Question 9

Location of the tapetum

Answer 9

Most domestic species have a reflective tapetum located in the superior fundus within the choroidal layer.

Question 10

Ossicles

Answer 10

These bony scleral structures are found in birds, some reptiles and amphibians and give support to the outer fibrous tunic.

Question 11

When do puppies and kitties open their eyes

Answer 11

puppies and kittens open their eyes at 10-14 days

Question 12

When do ferrets and guinea pigs open their eyes?

Answer 12

the guinea pig at birth and the ferret at 30 days.

Question 13

Adexa

Answer 13

refers to the tissues surrounding the eye (muscles, eyelids, 3rd eyelid, lacrimal gland, fat, nerves, vessels etc.).

Question 14

Muscles of the eye

Answer 14

rectus, oblique, retractor, smooth muscle

Question 15

rectus muscles and innervation

Answer 15

Dorsal, Ventral, Medial (innervated by CN III-oculomotor)

Lateral (innervated by CN VI-abducens)

Question 16

Oblique muscles, actions, and innervation

Answer 16

Dorsal Oblique; (innervated by Crn IV-trochlear): rotates dorsal globe
medially and ventrally
Ventral Oblique; (innervated by Crn III-oculomotor), rotates the ventral
globe medially and dorsally

Question 17

Innervation of the retractor muscle

Answer 17

(innervated by Crn VI-abducens); not found in the bird

Question 18

smooth muscle of the eye is under what control?

Answer 18

sympathetic

Question 19

3 layers of the eye

Answer 19

Outer fibrous tunic (cornea & sclera)
Middle vascular layer- Uvea (iris, ciliary body & choroid)
Inner nervous layer (retina)

Question 20

Outer fibrous tunic

Answer 20

(cornea & sclera)

Question 21

Middle vascular layer-

Answer 21

Uvea (iris, ciliary body & choroid)

Question 22

Inner nervous layer

Answer 22

(retina)

Question 23

What produces the aqueous humor?

Answer 23

This clear fluid, produced by the ciliary processes (located behind iris)

Question 24

Flow of aqueous humor

Answer 24

passes through the pupil into the anterior chamber and exits the eye via the iridocorneal angle (ICA)

Question 25

Function of aqueous humor

Answer 25

It provides nourishment for the cornea and lens and maintains intraocular pressure.

Question 26

How to visualize the aqueous humor in the dog, cat and horse?

Answer 26

ICA can be visualized using a goniolens in the dog but can be seen by viewing obliquely across the cornea in the cat, and directly at the medial and lateral limbus in the horse.

Question 27

vitreous

Answer 27

This is the largest area of the eye.

Question 28

What is vitreous humor

Answer 28

Vitreous humor is a clear gel-like fluid that occupies the space between the lens and the retina. It gives both nutritional and structural.
support to the lens and the retina.

Question 29

Retina

Answer 29

The inner nervous layer of the eye

Question 30

When can the retina been seen?

Answer 30

can only be visualized if the cornea, aqueous, lens and vitreous are transparent.

Question 31

Retina is made up of what?

Answer 31

It is composed of axons of the retinal ganglion cells that converge to form the optic nerve.