Ophthalmology - Exam and Orbit Flashcards Preview

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Flashcards in Ophthalmology - Exam and Orbit Deck (41)
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1
Q

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

A

CN V - afferent

CN VII - efferent

2
Q

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

A

CN II - afferent

CN VII - efferent

3
Q

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

A

CN II - afferent

CN III - efferent

4
Q

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

A

CN II - afferent

CN VII - effernet

5
Q

What is the afferent component of the corneal reflex?

A

CN V

6
Q

When is the Shirmer tear test performed?

A
  • before any other drops or ointments

- before sedation or anesthesia

7
Q

How is the Shirmer tear test performed?

A
  • test strip is placed laterally in the conjuctival sac
  • close the eyes and leave the strip in for 60 seconds
  • measuring tear production
8
Q

What is the normal value for the Shirmer tear test?

A
  • unpredictable in cats

- dogs: > 15mm/minute

9
Q

What is Fluorescein stain?

A

hydrophilic dye that fluoresces green under cobalt blue light

10
Q

When is a Fluorescein stain done?

A
  • diagnosis and characterization of corneal ulceration
  • demonstration of nasolacrimal patency
  • demonstration of corneal perforation
11
Q

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

A
  • measures intraocular pressure

- the lowest reading is the most accurate

12
Q

What is the normal intraocular pressure measurement?

A

10-20 mmHg

< 8 mmHg difference between eyes

13
Q

Describe the the features of direct ophthalmoscopy in respect to indirect

A
Direct:
- higher magnification
- lower field of view
- lower depth perception
- easier to use
- less safe
Indirect: image is reversed and upside-down
14
Q

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

A

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

15
Q

What is retropulsion?

A

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

16
Q

What is specular reflection?

A

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

17
Q

Which tooth is commonly involved in orbital/periorbital disease?

A

the carnassial tooth

4th premolar

18
Q

Which nerves pass through the orbital fissure?

A

CN III, IV, V, VI

19
Q

What is exophthalmos?

A

abnormal protrusion of the eye from the orbit

20
Q

What are the clinical signs associated with exophthalmos?

A
  • third eyelid protrusion
  • facial swelling
  • soft palate bulging
  • pain on opening mouth
  • fever
21
Q

What are possible causes of exophthalmos?

A
  • orbital volume imbalance
  • orbital neoplasia
  • orbital cellulitis/abscess
  • zygomatic salivary gland mucocele
  • masticatory muscle myositis
  • extraocular myositis
  • retrobulbar hemorrhage
22
Q

What are the treatment options for orbital neoplasia?

A
globe-sparing
- radiation
- surgical exploration
- chemotherapy
globe removal
- enucleation
- exenteration
23
Q

What are the treatment options for orbital cellulitis/abscess?

A
  • anti-inflammatory therapy and antibiotics

- surgical exploration and/or drainage

24
Q

What is enophthalmos?

A

abnormal recession of the eye within the orbit

25
Q

What are the clinical signs associated with enophthalmos?

A
  • facial muscular loss
  • third eyelid protrusion
  • entropion
26
Q

What are the possible causes of enophthalmos?

A
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
27
Q

What is microphthalmos?

A

a congenitally small globe

28
Q

What is phthisis bulbi?

A

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

29
Q

What is strabismus?

A

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

30
Q

What are the possible causes of strabismus?

A
congenital:
- brachycephalics and siamese cats
- hydrocephalus
acquired:
- dysfunction of any rectus muscle
- imbalance of orbital volume
31
Q

What is proptosis?

A

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

32
Q

What are positive prognostic factors for proptosis?

A
  • brachycephalics
  • < 3 extraocular muscles torn
  • positive direct and indirect PLRs
33
Q

What are negative prognostic factors for proptosis?

A
  • cats and doliochocephalics
  • > 3 extraocular muscles torn
  • ruptured eye
  • hyphema
  • orbital fractures
34
Q

What is the vision prognosis for proptosis?

A

75-80% will be blind

35
Q

How is proptosis treated?

A
  • lubricate the cornea

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

36
Q

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

A
  • corneal ulceration
  • loosening of sutures
  • strabismus
  • KCS
  • blindness
  • repeated proptosis
  • need for enculeation
37
Q

Describe the anatomic features of the orbit in brachycephalic dogs

A
  • orbital ligament spans a greater portion of the orbital rim
  • orbit is much shallower
  • more susceptible to ocular disease
38
Q

What is the periorbital cone?

A

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

39
Q

What is the orbital ligament?

A

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

40
Q

What is buphthalmos?

A

abnormal enlargement of the eyeball

41
Q

What is Horner’s Syndrome?

A

sympathetic denervation to the eye and ocular adnexa