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NEU2 > Ophthalmic examination > Flashcards

Ophthalmic examination Flashcards

1
Q

What elements can be assessed in the distant ophthalmic examination?

A
  • Facial symmetry
  • Ocular symmetry
  • Ocular discharge
  • Eyes open or closed
  • Size of palpebral fissure
  • Position of third eyelid
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2
Q

What is the Purkinje image and what can it indicate?

A
  • Is the reflection of image on surface of eye, e.g. corneal reflex
  • Disturbed image can indicate poor tear film, irregular corneal surface etc.
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3
Q

What ophthalmic condition are Westies predisposed to?

A

Dry eye (keratoconjunctivitis sicca)

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4
Q

What ophthalmic condition are terriers predisposed to?

A

Lens luxation

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5
Q

What is hyphaema?

A

Blood in the anterior chamber of the eye

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6
Q

What are the common causes of hyphaema in the puppy?

A
  • Congenital anomaly

- Trauma

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7
Q

What would hyphaema in a 12yo dog be suggestive of?

A

Intraocular neoplasm

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8
Q

What would hyphaema in a 12yo cat be suggestive of?

A

Systemic hypertension

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9
Q

What might uveitis in an entire female be indicative of?

A

Pyometra

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10
Q

What points should be addressed in an ophthalmic history?

A
  • When problem started
  • Gradual or sudden onset
  • Progressive
  • One or both eyes
  • Pain
  • Vision (day vs night, familiar vs unfamiliar surroundings)
  • Change in appearance of eye
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11
Q

List the reflexes assessed in an ophthalmic examination

A
  • Palpebral
  • Menace
  • Dazzle
  • Pupillary light
  • Vestibulo-ocular
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12
Q

What does the palpebral reflex assess?

A

Skin sensation and ability to blink, good to perform before other tests to avoid false negatives if cannot blink

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13
Q

What does the menace response assess?

A

Not true reflex, assesses vision (and ability to blink)

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14
Q

Compare the age at which the menace response develops in different species

A
  • Dog and cats from 12 weeks old

- Present in foals at 1-2 days old

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15
Q

What does the dazzle reflex assess?

A

The ability to detect light

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16
Q

What is the dazzle reflex and what are the afferent and efferent pathways?

A
  • Subcortical reflex
  • Both eyes blink and possible head withdrawal
  • Afferent: retina CN II, rostral colliculus, subcortical connections
  • Efferent: CN VII
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17
Q

Why might false negatives occur with a PLR?

A
  • Weak light source in daylight, not strong enough to elicit PLR
  • Animal scared, stressed, high level of SNS tone (repeat at end of consult)
  • Iris atrophy (age related atrophy of iris musculature)
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18
Q

What are the afferent and efferent pathways for the tracking reflex?

A
  • Afferent: CN II

- Efferent: CN III, IV, Vi, VIII

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19
Q

What are the afferent and efferent pathways of the corneal reflex?

A

Afferent: V (ophth) branch
Efferent: globe retraction by CN VI, blink by CN VII

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20
Q

What is the Schirmer tear test used for?

A

Quantitative measurement aqueous part of the basal and reflex tear production

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21
Q

Explain the correct placement of the Schirmer tear test strip

A

Place more laterally in the eye - if too medial will not get the reflex component due to third eyelid preventing this

22
Q

What would a normal STT value for a dog be?

A

15-25mm/minute

23
Q

What would the following STT values in the dog indicate?

a: <10mm/min
b: 10-15mm/min
c: >25mm/min

A

a: Diagnostic for dry eye
b: Diagnostic for dry eye if supportive clinical signs present, ideal time to start treatment
c: over production i.e. ocular irritation

24
Q

What would the normal STT values for a cat be?

A
  • Much more variable than the dog

- 5-10mm/min very common, textbooks tend to say 17mm/min

25
Q

What dioptre settings should be used for the following portions of the eye in direct ophthalmoscopy:

a: retina
b: lens
c: cornea

A

a: 0
b: 8-12
c: 20

26
Q

What are the advantages of distant direct ophthalmoscopy?

A
  • Highlight visual axis
  • Assess pupil size and clarity of visual axis
  • Opacities will be black and obvious e.g. cataract,, foreign body, ulcer
27
Q

List the different methods of ophthalmoscopy

A
  • Distant and close direct

- Monocular or binocular indirect

28
Q

What is stained by fluorescein dye?

A

Corneal stroma

29
Q

What are the normal intraocular pressures for:

a: dog and cat
b: horse
c: rabbit

A

a: 15-25mmHg
b: 17-28mmHg
c: 15-20mmHg

30
Q

What IOP difference between 2 eyes is abnormal?

A

> 10mmHg difference

31
Q

List the methods for tonometry in the small animal

A
  • Digital tonometry (fingers)
  • Indentation tonometry
  • Applanation tonometry
  • REbound tonometry
32
Q

Describe the method for and evaluate the use of digital tonometry in small animals

A
  • Place forefinger on globe through skin of upper eyelid, both eyes in unison for comparison
  • Allows estimate of very hard vs very soft eye and some comparison
  • Very inaccurate
33
Q

Describe the method and evaluate the use of indentation tonometry in small animals

A
  • Schiotz tonometer
  • Cumbersome, needs practice
  • Local anaesthetic drops on eye, tilt head back so cornea is horizontal
  • Place foot on eye and measure degree of indentation of metal rod on cornea
34
Q

Describe and evaluate the use of applanation tonometry

A
  • Very accurate, good for all species, but expensive
  • Local anaesthaetic drops
  • Measures flattening of the cornea against disposable latex tip
35
Q

Describe and evaluate the use of rebound tonometry

A
  • Very accurate, good for all species, expensive
  • Local anaesthetic not required
  • Hold in horizontal position, measures how fast pin rebounds from eye
  • faster rebound = harder eye
  • Disposable probe, no contamination
36
Q

What is the function of the Jones’ test?

A

Assesses patency of tear duct

37
Q

Describe the method for the Jones’ test

A
  • Apply flourescein to both eyes as normal
  • Observe for a few minutes
  • Positive: dye passes through nasolacrimal duct and visible at both nostrils within 2-5 mins in smallies, 5-20 mins in the horse
  • False negatives common
38
Q

What may lead to false negatives on a Jones’ test?

A
  • Dog licks nose
  • Accessory openings in mouth, need to look for green tongue, esp. in brachy breeds
  • Insufficient dye
  • Head too elevated
  • Insufficient time
39
Q

What is the purpose of the Seidel test?

A

Assessment of corneal integrity

40
Q

Describe the method and indications for the Seidel test

A
  • Indications: following removal of corneal FB, corneal laceration, suspicion of perforated corneal ulcer
  • Flourescein dye applied to eye but not flushed, aqueous humour leakage detected by clear fluid pushing fluoresein away from site of concern
41
Q

When is the use of corneal swabs indicated?

A
  • Suspect bacterial infection
  • Cats with ocular surface disease
  • In order to perform bacteriology, fungal culutre, PCR tests (for viruses)
42
Q

What are the most common causes of ocular surface disease in cats?

A
  • Chlamydophila felis
  • FHV-1
  • also: Mycoplasma felis, feline calicivirus, Bordatella bronchiseptica
43
Q

Describe the method for ocular swabbing

A
  • Apply local anaesthetic drops to eye
  • Retropulse globe through upper lid to protrude third eyelid
  • Roll swab several times in front of third eyelid (for conjunctivitis) or cornea (for corneal ulcer, tough edge of ulcer gently)
44
Q

Describe the method for performing a nasolacrimal flush

A
  • Can be conscious with local in some dogs, rabbits and horses, unless inexperienced with technique
  • In cats, small punctal opening so need GA
  • Cannulate upper punctum, attach 2ml syringe of water/saline, flush gently, look for fluid at lower punctum
  • Occlude lower punctum by external compression, continue flushing head down slightly, look for fluid at ipsilateral nostril
  • In horse, go retrograde from nostrils up (easier to find)
  • In rabbit, only have lower and no upper ppunctum
45
Q

Describe the vestibulo-ocular reflex

A
  • Aka dolls-head reflex, physiological nystagmus
  • Stimulus: change head position side to side, up and down
  • Normal response is that both eyes move together - fast phase in direction of movement, slow phase opposite to direction of movement
46
Q

What is gonioscopy?

A

Assessment of iridocorneal drainage angle

47
Q

How is gonioscopy performed and what are the indications for this?

A
  • Anaesthetic drops on eye first
  • Place contact lens on eye to look at drainage angle
  • Used to assess if are predisposed to hereditary glaucoma mainly
48
Q

What is slit-lamp biomicroscopy particularly useful for?

A

Assessment of depth and location of corneal lesions

49
Q

What is the function of electroretinography (ERG)? How is it performed?

A
  • Assessment of retinal function
  • Eye equivalent of ECG
  • Corneal electrode = contact lens
  • Skin electrodes and light source used
  • Produce waveform that demonstrates retinal function
50
Q

What does electroretinography allow determination of?

A

Whether blindness is due to the eye or the brain

NEU2 (23 decks)

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