Term
| T/F: The dog and cat have a completely bony orbit. |
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Definition
| False: the horse has a completely bony orbit, while the dog and cat have an open orbit, which makes them a little more prone to damage of the face that can harm structures of the eye. |
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Term
| The orbital lacrimal gland produces ____-____% of the aqueous tears, while the third eyelid gland produces ____-____% of the aqueous tears. |
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Definition
60-70% from orbital lacrimal gland
30-40% from third eyelid gland |
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Term
| Drainage of aqueous tears goes from the ________________ to the ________________ to the ________________ and exits from the ____________________. |
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Definition
Lacrimal puncta
Canaliculi
Nasolacrimal duct
Nasal punctum |
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Term
The oculomotor nerve is responsible for innervation of all of the following muscles except:
a. Superior rectus m.
b. Inferior oblique m.
c. Lateral rectus m.
d. Inferior rectus m.
e. Medial rectus m. |
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Definition
c. Lateral rectus m.
Innervated by CN6 (Abducens n.) |
|
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Term
The superior oblique muscle of the eye is innervated by:
a. CNIII
b. CNIV
c. CNVI
d. CNVII
e. None of the above |
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Definition
|
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Term
The abducent nerve is responsible for innervation of the:
a. Lateral Rectus Muscle
b. Retractor Bulbi Muscle
c. Medial Rectus Muscle
d. A and B
e. B and C |
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Definition
|
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Term
| T/F: the eyelids have a muscle called Muller's muscle, which has sympathetic innervation and is the reason why animals with Horner's syndrome have ptosis. |
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Definition
|
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Term
| T/F: the third eyelid is made up of cartilage and a lacrimal gland. |
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Definition
| True--the lacrimal gland is responsible for 30-40% of aqueous tear production, which is why it is important to try and preserve the third eyelid gland when doing surgery/treatment. |
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Term
| List four types of conjunctiva (based on location) found in the eye: |
|
Definition
Bulbar
Palpebral
Nicitans
Fornices |
|
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Term
| The vascular tunic is made up of the __________, ___________, and _____________. |
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Definition
|
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Term
All of the following are layers of the cornea except:
a. Epithelium
b. Stroma
c. Descemet's membrane
d. Endothelium
e. Sclera |
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Definition
|
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Term
| In the cornea, the ____________ and _____________ are lipophilic, while the ________________ is hydrophilic. The ______________ is the thickest layer of the cornea. |
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Definition
Epithelium, Descemet's membrane are lipophilic
Stroma is hydrophilic
Stroma is thickest |
|
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Term
The ______________ removes fluid from the cornea to maintain relative dehydration/clarity.
a. Epithelium
b. Stroma
c. Descemet's membrane
d. Endothelium
e. None of the above |
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Definition
|
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Term
| T/F: the stroma in the cornea is made up of irregularly arranged collagen fibers, while the sclera is made up of regularly arranged collagen fibers. |
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Definition
False
Stroma = regularly arranged collagen
Sclera = irregularly arranged collagen |
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Term
| The ________________ is the area of transition from cornea to sclera. |
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Definition
|
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Term
| The ________________ is the area of transition from cornea to sclera. |
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Definition
|
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Term
The weakest point of the eye is the:
a. Limbus
b. Lamina cribrosa
c. Retina
d. Iris
e. Lens |
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Definition
|
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Term
| The uvea is made up of the _____________, _____________, and _____________. |
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Definition
|
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Term
| T/F: pupillary membranes are clinically significant in the dog. |
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Definition
| False: residual change when embryonic vasculature is not broken down completely |
|
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Term
The pupillary ruff:
a. Refers to a pupillary difference in large animal species
b. Is sometimes referred to as the corpora nigrans
c. Is sometimes referred to as the granula iridica
d. A and B
e. A, B, and C |
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Definition
|
|
Term
Innervation to the pupillary sphincter muscle is through:
a. CNII
b. CNIII
c. CNIV
d. CNVI |
|
Definition
|
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Term
| T/F: the pupillary sphincter muscle is stronger than the pupillary dilator muscle, so when the eye is inflamed, miosis will occur. |
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Definition
|
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Term
| T/F: innervation to the pupillary dilator muscle is parasympathetically mediated. |
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Definition
| False. Sympathetically mediated. |
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Term
The ciliary body:
a. has zonular attachments that go 360 degrees around the lens to hold the lens in place
b. produces aqueous humor through its non-pigmented epithelial cells
c. Has zonules that contract for near vision
d. Has zonules that relax for far vision
e. All of the above |
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Definition
|
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Term
| T/F: the majority of aqueous humor drains out the iridocorneal angle. |
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Definition
| True. There is a second pathway that allows absorption by the stroma, which can be medically mediated for glaucoma treatment. |
|
|
Term
The normal intraocular pressure for horses is:
a. 5-10 mmHg
b. 10-20 mmHg
c. 20-30 mmHg
d. 30-40 mmHg
e. 40-50 mmHg |
|
Definition
c. 20-30 mmHg
Dogs/cats are 10-20 mmHg |
|
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Term
Lens fibers:
a. Are regularly exposed to the rest of the eye
b. Undergo aging degeneration called nuclear sclerosis that is the equivalent to cataracts.
c. Will stimulate inflammation in the eye if the lens fibers are recognized as foreign antigen
d. A and B
e. A, B, and C |
|
Definition
c. will stimulate inflammation
The lens fibers are never exposed to the eye--if the lens is damaged, this will stimulate inflammation in the eye because it is a foreign antigen in the eye. Nuclear sclerosis is an aging process, but is NOT equivalent to cataracts. |
|
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Term
The _______________ maintains eye shape and retinal position, transmits light, and is 99% water.
a. Aqueous humor
b. Uvea
c. Vitreous body
d. Retina
e. Cornea |
|
Definition
c. Vitreous
The retina is only connected at the aura and at the optic nerve, so vitreous helps maintain retinal position |
|
|
Term
The fundus is made up of:
a. Retina
b. Choroid
c. Tapetum
d. Sclera
e. All of the above |
|
Definition
e. all of the above
The tapetum is a structure that gives the retina a second chance at processing light |
|
|
Term
| The workhorses of the retina are the __________________. |
|
Definition
Photoreceptors
Rods--dim light, peripheral vision
Cones--daylight, color, visual acquity |
|
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Term
| If an animal has an anangiotic vascular pattern in the retina, where does the vascular supply come from? |
|
Definition
The choroid
Various vascular patterns: Merangiotic, anangiotic, paurangiotic, holangiotic |
|
|
Term
The choroid:
a. Contains the stars of Winselow
b. Is typically pigmented
c. Sometimes contains the tapetum, which reflects unabsorbed light rays back to photoreceptors.
d. A and B
e. A, B, and C |
|
Definition
e. A, B, and C
Note that the stars of Winselow are another name for the choriocapillaries, which are responsible for being the main nutrition source for the outer retina |
|
|
Term
| _____________ do not have much myelin around their optic nerve, making it appear black, rather than white. |
|
Definition
|
|
Term
| The _______________ gives photoreceptors a second chance at light. |
|
Definition
|
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Term
| Describe the visual pathway: |
|
Definition
| Optic nerve-->optic chiasm-->decussation (50-100% depending on species)-->optic tract where 80% of fibers go to the lateral geniculate nucleus of the thalamus-->optic radiations-->cerebral cortex (occipital lobe)-->visual processing |
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Term
| Describe the PLR pathway: |
|
Definition
| Optic nerve-->optic chiasm-->species specific decussation-->optic tract to pretectal nuclei (20% of fibers)-->decussation-->parasympathetic nuclei of CNIII -->parasympathetic fibers of CNIII synapse in ciliary ganglion-->short posterior ciliary nerves terminate at iris sphincter |
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|
Term
| T/F: a blind dog can have a normal PLR |
|
Definition
True
Any impediment to ocular clarity can provide a normal PLR but cause the dog to be functionally blind. Similarly, dogs with brain disease where the optic centers aren't functioninc properly may have an optic nerve that is functioning just fine. |
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