Ophthalmology - Exam and Orbit

Question 1

What are the afferent and efferent components of the palpebral reflex?

Answer 1

CN V - afferent

CN VII - efferent

Question 2

What are the afferent and efferent components of the menace response?

Answer 2

CN II - afferent

CN VII - efferent

Question 3

What are the afferent and efferent components of the pupillary light reflex?

Answer 3

CN II - afferent

CN III - efferent

Question 4

What are the afferent and efferent components of the dazzle reflex?

Answer 4

CN II - afferent

CN VII - effernet

Question 5

What is the afferent component of the corneal reflex?

Answer 5

CN V

Question 6

When is the Shirmer tear test performed?

Answer 6

• before any other drops or ointments

- before sedation or anesthesia

Question 7

How is the Shirmer tear test performed?

Answer 7

• test strip is placed laterally in the conjuctival sac
• close the eyes and leave the strip in for 60 seconds
• measuring tear production

Question 8

What is the normal value for the Shirmer tear test?

Answer 8

• unpredictable in cats

- dogs: > 15mm/minute

Question 9

What is Fluorescein stain?

Answer 9

hydrophilic dye that fluoresces green under cobalt blue light

Question 10

When is a Fluorescein stain done?

Answer 10

• diagnosis and characterization of corneal ulceration
• demonstration of nasolacrimal patency
• demonstration of corneal perforation

Question 11

What does tonometry measure, and how are the results interpreted?

Answer 11

• measures intraocular pressure

- the lowest reading is the most accurate

Question 12

What is the normal intraocular pressure measurement?

Answer 12

10-20 mmHg

< 8 mmHg difference between eyes

Question 13

Describe the the features of direct ophthalmoscopy in respect to indirect

Answer 13

Direct:
- higher magnification
- lower field of view
- lower depth perception
- easier to use
- less safe
Indirect: image is reversed and upside-down

Question 14

What are the abbreviations for right, left, and both eyes?

Answer 14

OD - right eye
OS - left eye
OU - both eyes

Question 15

What is retropulsion?

Answer 15

applying light pressure to both eyes through the lids to detect for asymmetry

Question 16

What is specular reflection?

Answer 16

the mirror-like reflection of light form the surface of the eye

Question 17

Which tooth is commonly involved in orbital/periorbital disease?

Answer 17

the carnassial tooth

4th premolar

Question 18

Which nerves pass through the orbital fissure?

Answer 18

CN III, IV, V, VI

Question 19

What is exophthalmos?

Answer 19

abnormal protrusion of the eye from the orbit

Question 20

What are the clinical signs associated with exophthalmos?

Answer 20

• third eyelid protrusion
• facial swelling
• soft palate bulging
• pain on opening mouth
• fever

Question 21

What are possible causes of exophthalmos?

Answer 21

• orbital volume imbalance
• orbital neoplasia
• orbital cellulitis/abscess
• zygomatic salivary gland mucocele
• masticatory muscle myositis
• extraocular myositis
• retrobulbar hemorrhage

Question 22

What are the treatment options for orbital neoplasia?

Answer 22

globe-sparing
- radiation
- surgical exploration
- chemotherapy
globe removal
- enucleation
- exenteration

Question 23

What are the treatment options for orbital cellulitis/abscess?

Answer 23

• anti-inflammatory therapy and antibiotics

- surgical exploration and/or drainage

Question 24

What is enophthalmos?

Answer 24

abnormal recession of the eye within the orbit

Question 25

What are the clinical signs associated with enophthalmos?

Answer 25

- facial muscular loss - third eyelid protrusion - entropion

Question 26

What are the possible causes of enophthalmos?

Answer 26

``` orbital volume imbalances: - dehydration, emaciation - myopathies, space occupying lesions anterior to globe active globe retraction: - skeletal muscle - ocular pain passive globe retraction: - smooth muscles - Horner's syndrome ```

Question 27

What is microphthalmos?

Answer 27

a congenitally small globe

Question 28

What is phthisis bulbi?

Answer 28

an acquired shrunken globe, most often from severe or chronic inflammation

Question 29

What is strabismus?

Answer 29

deviation of one or both eyes, so that both eyes are not directed at the same object

Question 30

What are the possible causes of strabismus?

Answer 30

``` congenital: - brachycephalics and siamese cats - hydrocephalus acquired: - dysfunction of any rectus muscle - imbalance of orbital volume ```

Question 31

What is proptosis?

Answer 31

anterior displacement of the globe such that the eyelids are caught behind the equator of the globe

Question 32

What are positive prognostic factors for proptosis?

Answer 32

- brachycephalics - < 3 extraocular muscles torn - positive direct and indirect PLRs

Question 33

What are negative prognostic factors for proptosis?

Answer 33

- cats and doliochocephalics - > 3 extraocular muscles torn - ruptured eye - hyphema - orbital fractures

Question 34

What is the vision prognosis for proptosis?

Answer 34

75-80% will be blind

Question 35

How is proptosis treated?

Answer 35

- lubricate the cornea | - replacement: horizontal mattress sutures, push eye down with flat edge and pull sutures up, temporary tarsorrhaphy

Question 36

What are the possible complications that can result from proptosis replacement?

Answer 36

- corneal ulceration - loosening of sutures - strabismus - KCS - blindness - repeated proptosis - need for enculeation

Question 37

Describe the anatomic features of the orbit in brachycephalic dogs

Answer 37

- orbital ligament spans a greater portion of the orbital rim - orbit is much shallower - more susceptible to ocular disease

Question 38

What is the periorbital cone?

Answer 38

supportive cone-like structure that contains the eyeball, extraocular muscles, fat, vessels, nerves, and fascia, that reside within the orbit

Question 39

What is the orbital ligament?

Answer 39

ligamentous structure that forms the lateral boundary of the boney orbit in cats and dogs

Question 40

What is buphthalmos?

Answer 40

abnormal enlargement of the eyeball

Question 41

What is Horner's Syndrome?

Answer 41

sympathetic denervation to the eye and ocular adnexa