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Investigations > Ocular motility examination > Flashcards

Ocular motility examination Flashcards

1
Q

What are 9 stages to ocular motility examination?

A
  1. note visual acuity
  2. observe head posture
  3. Hirschberg test
  4. Cover/uncover + alternate cover test
  5. Examine ductions and vertions into 9 positions of gaze
  6. Examine horizontal and vertical saccades
  7. Examine convergence
  8. Examine horizontal / vertical doll’s head movements
  9. Examine horizontal / vertical optokinetic nystagmus (OKN)
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2
Q

What does Hirschberg test test for?

A

to detect/ estimate the size of a manifest deviation

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3
Q

What does the cover/uncover + alternate cover test test for?

A

manifest or latent deviation

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4
Q

What are 4 different ways the cover/uncover + alternate cover tests should be performed?

A
  1. With/without glasses
  2. Near (1/3m) target
  3. Distance (6m) target
  4. Non-accommodative
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5
Q

How are ductions and versions into 9 positions of gaze examined?

A
  1. ask patient to follow target (usually a pen torch)
  2. perform cover test in each position
  3. ask patient to report any diplopia in primary position or during test
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6
Q

How are horizontal and vertical saccades examined?

A

ask pt to look rapidly between targets postioned at 30 degrees on either side of the midline

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7
Q

How is convergence assessed?

A

assess to both an accommodative and non-accommodative target

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8
Q

How are horizontal / vertical optokinetic nystagmus examined?

A

slowly rotate an OKN drum in horizontal and vertical directions

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9
Q

How are ocular deviations classified?

A
  • manifest or latent
  • concomitant (constant in all positions of gaze) or incomitant (varying)
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10
Q

What are 2 things to determine for incomitant deviations?

A
  1. direction of maximum separate of diplopic images
  2. type of pattern: neurogenic, mechanical, myasthenic, supranuclear, myopathic
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11
Q

What are 5 types of pathological incomitant deviation pattern?

A
  1. Neurogenic
  2. Mechnical
  3. Supranuclear
  4. Myasthenic
  5. Myopathic
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12
Q

How is Hirschberg’s test performed?

A

patient asked to fix on a pen-torch at 1/3m, note corneal reflections
normal position is just nasal to the centre of the cornea

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13
Q

What is the normal position of the light reflection in Hirschberg’s test and what does each degree of displacement equate to?

A

normal = just nasal to centre of cornea
every 1mm deviation represents 7 degrees of 15 prisms

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14
Q

What does it represent if the reflection in Hirschberg test is deflected nasally?

A

eye is divergent (i.e. exotropic)

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15
Q

What does it represent if the reflection in Hirschberg test is deflected temporally?

A

eye is convergent i.e. esotropic

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16
Q

Which Purkinje image does Hirschberg test make use of?

A

1st Purkinje image

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17
Q

What is a second corneal reflection test in addition to Hirschberg test?

A

Krimsky test

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18
Q

What does the Krimsky test involve?

A

deviation measured by placing prism bar in front of deviating eye and finding prism strength at which the corneal reflexes are symmetrical

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19
Q

How should the prism be oriented in the Krimsky test?

A

oriented to point in the direction of deviation i.e. base out for an esotropia, base in for an exotropia

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20
Q

What are the 3 types of cover tests?

A
  1. cover-uncover test
  2. alternate cover test
  3. prism cover test
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21
Q

What does the cover part of the cover-uncover test test for?

A

manifest deviation

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22
Q

How is the cover part of the cover-uncover test performed?

A
  • ask patient to fix on a target (near, distance, non-accommodative, sometimes far distance)
  • occlude each eye in turn (starting with fixing eye and observe any movement of the uncovered eye
  • inward movement indicates the eye was previously divergent (exotropic), downward indicates was hypertropic
23
Q

How is the uncover part of the cover-uncover test performed?

A

occlude first eye again for a few seconds, look for any movement of the covered eye as the occluder is removed.
repeat for other eye
inward movement indicates occluded eye has drifted out (i.e. exophoric)

24
Q

What type of deviation does the uncover part of the cover-uncover test reveal?

A

latent deviation

25
Q

Why should the cover test be repeat in all 9 positions of gaze? 2 reasons

A
  1. to identify the direction of maximum separation of diplopia (indicates direction of paretic muscle action/maximum restriction
  2. compare ductions and versions
26
Q

What does the alternate cover test detect?

A

detects the total deviation (latent and manifest) by causing dissociation of binocular single vision (BSV)

27
Q

How is the alternate cover test performed?

A
  • ask patient to fix on a target (near/distant/non-accommodative)
  • repeatedly cover each eye in turn for 2-3s so 1 eye is always covered
  • direction and amplitude of any deviation is noted
  • once BSV is broken down, remove the occluder and note the speed of recovery of each eye in turn
28
Q

In addition to detecting total deviation, what are 2 further things that the laternate cover test can identify?

A
  1. dissociated vertical deviation (DVD)
    manigest latent nystagmus (MLN)
29
Q

In what condition are DVD and MLN common?

A

infantile esotropia

30
Q

What does the prism cover test measure?

A

angle of deviation

31
Q

How is the prism cover test performed?

A

repeat alternate cover test but with a prism bar in front of one eye, adjusting the prism strength until first neutralisation and then reversal of the corrective movement occurs

32
Q

How should the prism be oriented in prism cover test?

A

pointing in direction of deviation

33
Q

How do Maddox tests work in in general (rod and wing) and what are they used for?

A
  • involve presenting different images to each eye
  • sued for assessing symptomatic phorias
34
Q

What is a manifest squint?

A

present when the eyes are open and being used

35
Q

What is a latent squint?

A

eye turns only when it is covered or shut

36
Q

What do Maddox rod vs. wing vs. 2 Maddox rods test for?

A
  1. rod = distance
  2. wing = near
  3. 2 rods = torsional
37
Q

How does the Maddox rod test work?

A
  • e.g. Maddox rod (series of red cylinders) placed horizontally in front of the right eye, pt (with distance correction) fixates on a distant spot of white light
  • will see vertical red line and white spot - if there is no phoria, the line will pass straight through the spot
  • if the image is crossed (i.e. line is to the left of the light) there is an exophoria and vice versa
38
Q

How is a phoria quantified using a Maddox rod?

A

finding the prism required to neutralise it

39
Q

What does it indicate with Maddox rod testing if the line is below the light?

A

hyperphoria

40
Q

How is Maddox wing testing performed?

A
  • patient, wearing reading correction, looks through apertures to view vertical and horizontal arrow (with the R eye) and corresponding vertical and horizontal scales (with the left eye)
  • numbers indicated by the arrows (as seen by pt) indicate direction and size of near phoria
41
Q

How is the double Maddox rod test performed?

A
  • horizontally oriented Maddox rod placed in front of each eye (one red, one write)
  • colour of the tilted line is identified by pt
  • corresponding Maddox rod rotated until pt reports it is vertical
  • rotation required indicates size of torsion
42
Q

Whe will the two lines fuse in the double Maddox rod test?

A

if there is no residual non-torsional deviation

43
Q

What is the Parks-Bielschowsky 3-step test used for?

A

to identify a single underacting muscle in vertical/torsional deviations - particularly useful in superior oblique palsies

44
Q

What are the 3 steps of the Parks-Bielschowsky 3 step test?

A
  1. Perform cover test in** primary position,** identify higher eye
  2. Perform cover test with gaze to right, then left; identify where separation (and diplopia) is greatest
  3. Perform cover test with head tilt to right, then left shoulder; identify where separation (and diplopia) is greatest
45
Q

What are the 3 steps of the Parks-Bielschowsky 3 step test?

A
  1. Perform cover test in** primary position,** identify higher eye
  2. Perform cover test with gaze to right, then left; identify where separation (and diplopia) is greatest
  3. Perform cover test with head tilt to right, then left shoulder; identify where separation (and diplopia) is greatest
46
Q

What is step 2 of the Parks-Bielschowky test based on?

A

eye positionwhere the greatest vertical action occurs - for obliques, this is when eye is adducted; for vertical recti, this is when eye is abducted

47
Q

What is step 3 of the Parks-Bielschowsky 3-step test based on?

A

fact that superior muscles intort the eyes, whereas inferior muscles extort

48
Q

What will the steps of the Parks-Bielschowsky steps each show in right SO underaction?

A
  1. R eye higher eye in primary position
  2. Disparity greatest on gaze to the left
  3. Disparity greatest on head tilt to the right
49
Q

What is the interpretation of each possible outcome of the Parks-Bielschowsky 3-step test?

A
50
Q

What do caloric tests test?

A

vestibular/nuclear/infranuclear pathways

51
Q

In which group of patients can caloric tests be useful?

A

pts with reduced consciousness

52
Q

In what position should caloric tests be performed?

A

head inclined backwards at 60 degrees

53
Q

How are caloric tests performed and how can the result be interpreted?

A

water placed in either ear causes nystagmus, with the fast phase as follows: Cold - opposite, warm - same (COWS)

Investigations (29 decks)

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