Ocular Anatomy and Pharmacology Flashcards

1
Q

Which animals have a complete orbital ring?

A
Horse
Ox
Sheep
Cattle
Goat
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2
Q

Which animals have an incomplete ocular ring?

A

Pig
Dog
Cat

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3
Q

What are the bones that comprise the orbital anatomy (species dependent)? (7)

A
Frontal
Temporal
Zygomatic
Maxillary
Lacrimal
Sphenoid
Palatine
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4
Q

What bone does a dog’s orbit “lack” and what structure takes its place?

A

Temporal

Supraorbital ligament

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5
Q

What foramina are present in a dog’s orbit? (4)

A

Ethmoidal
Optic
Orbital fissure
Alar

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6
Q

What bones does a horse’s orbit “lack?”

A

Maxillary and palatine

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7
Q

What are the foramina present in a horse’s orbit? (5)

A
Ethmoidal
Optic
Orbital fissure
Rostral alar
Supraorbital
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8
Q

What are the four rectus muscles, two oblique muscles, and other muscle attached to the eye?

A

Superior/dorsal
Inferior/ventral
Medial
Lateral

Superior/dorsal
Inferior/ventral

Retractor bulbi

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9
Q

What muscles does CN3 innervate?

A

Dorsal, medial, ventral rectus

Ventral oblique

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10
Q

What muscles does CN4 innervate?

A

Dorsal oblique

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11
Q

What muscles does CN6 innervate?

A

Lateral rectus

Retractor bulbi

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12
Q

What are the three locations of conjunctiva?

A
Bulbar
Palpebral
Third eyelid
- Anterior
- Posterior
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13
Q

What are the functions of the conjunctiva?

A
Tear film
Reduce friction of blinking
Anatomic barrier
Immunity
Others
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14
Q

What are the areas of the lacrimal system?

A
Orbital lacrimal gland
Gland of the third eyelid
Nasolacrimal duct
- 2 punctae
- Punctum -> cannaliculus -> Lacrimal sac -> duct -> nose
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15
Q

What are the three tunics of the eye?

A

Fibrous
Vascular
Sensory

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16
Q

What are the parts of the fibrous layer of the eye and what do they do?

A

Cornea and sclera

Support and protection; provides shape to the eye

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17
Q

What are the parts of the vascular layer of the eye and what do they do?

A

Uveal tract (pigmented) - Iris, ciliary body, choroid

Provide nutrients, oxygen
Removes waste products
Aqueous humor production
Lens accomodation
Pupil shape
18
Q

What are the muscles of the iris?

A

Sphincter muscle to constrict pupil

Dilator muscle to open pupil

19
Q

What are the parts and functions of the ciliary body?

A
Anchor fibers that support lens
Produce aqueous humor
Contain muscles that alter lens shape
- Accomodation
- Near vs. distance vision
20
Q

Where does the trabecular pathway exit the pupil into the cornea?

A

Iridocorneal angle

21
Q

What happens if an animal has a closed iridocorneal angle?

A

Increased risk of glaucoma dt increased IOP

22
Q

What is the sensory layer of the eye and what does it do?

A

Retina
Highly developed structure
Needs precise arrangement for optimal function
Species differences

23
Q

How many layers does the retina have?

A

10

24
Q

What are the structures present in the lens?

A
Lens capsule
Anterior lens epithelium
Lens fibers
- Cortex
- Nucleus
Lens proteins
Water

*Fibers added throughout life

25
Q

What structures support the lens and how do they function?

A

Zonules
Vitreous
Iris

Help focus light on the retina
Free of nerves and blood vessels

26
Q

What structures comprise the fundus?

A
Vitreous
Retina
- Vessels
- Tapetum
- Non-tapetum
Optic disc
27
Q

What retinal vascular pattern do dogs and cats have and what does that mean?

A

Holngiotic

The entirety of the retina is perfused by retinal vessels

28
Q

What vascular pattern do horses have and what does it mean?

A

Paurangiotic

Tiny vessels only extend into retina a few mm, poorly vascularized

29
Q

What vascular pattern do birds have and what does it mean?

A

Anangiotic

Blood supply comes from the choroid

30
Q

What vascular pattern do rabbits have and what does it mean?

A

Merangiotic

Retinal vessels only medially and laterally from optic nerve

31
Q

What is the order in which eye drops should be applied?

A

Watery
Oily
Gels
Ointments

  • Wait 5 minutes between drops
  • Only administer 1 drop at a time
  • Ocular surface holds 10-25uL
32
Q

What areas of the eye are accessed via topical administration?

A
Eyelids
Conjunctiva
Cornea
- Epithelium is main site of resistance to drug penetration
- Fat-water-fat sandwich
Iris
Anterior uvea
33
Q

Sobconjunctival injection facts

A
Max volumes
- SA: .25mL
- LA: 1.0mL
27g or 25g needle
Bulbar conjunctiva
Used alone or along with topical therapy
34
Q

What areas of the eye does subconjunctival injection reach?

A

Cornea
Anterior uvea
Anterior vitreous
Sclera

Most typically utilized for corticosteroid delivery
Duration of subconjunctival injection
- Prednisone 24-48h
- Triamcinolone 2-3wk
- Methylprednisolone 3-4wk
- Betamethasone 3-4wk
35
Q

Retrobulbar injection facts

A
Performed for local anesthesia
Typically used in large animals
Options:
- Caudal to dorsal orbital rim
- Peterson block
- 4 point block
Lidocaine is most common
36
Q

Ocular implant facts

A
Sustained release of drug to ocular tissues
Vet med = cyclosporine implant
Most common uses:
- Episcleral cyclosporine implant
 - Dry eye diseases
 - Immune-mediated keratitis
- Suprachoroidal implant
 - Equine recurrent uveitis
37
Q

Systemic administration facts

A

Generally does not penetrate the anterior segment as well as topical or subconjunctival medications
Blood-ocular barrier prevents access to eye
Provides treatment for
- Retina
- Optic nerve
- Vitreous
Often required for eyelid diseases

38
Q

Subpalpebral lavage facts

A
  • Medication administration system through eyelid
  • Input medications in system at animal’s shoulder
  • Medication “pushed” up to eye by flushing with air
  • Commercial kit available from Mila International
  • Allows frequent medication administration
  • Only aqueous based medications should be used
  • Not for creams or ointments
  • Wait 5 min between meds
  • Most commonly used in horses
  • Minimizes risks
  • Less risk for eye trauma from syringe or ointment tube
  • No pressure on eye for administration
  • Well tolerated by animal - less stressful
  • Minimal placement side effects
39
Q

CRI pump facts

A

Attaches to subpalpebral lavage catheter
Automated delivery system
Preset to specific rate (1-7d to give 10mL)
Commercially available

NOT RECOMMENDED FOR USE AT THIS TIME

40
Q

What is the triple Abx combination and why is it effective?

A

Neomycin
Polymyxin
Bacitracin - ointment
Gramicidin - sol’n

Inexpensive and broad spectrum

41
Q

T/F: Triple Abx are very effective in cats

A

False; DO NOT USE IN CATS