Ocular motility examination Flashcards
What are 9 stages to ocular motility examination?
- note visual acuity
- observe head posture
- Hirschberg test
- Cover/uncover + alternate cover test
- Examine ductions and vertions into 9 positions of gaze
- Examine horizontal and vertical saccades
- Examine convergence
- Examine horizontal / vertical doll’s head movements
- Examine horizontal / vertical optokinetic nystagmus (OKN)
What does Hirschberg test test for?
to detect/ estimate the size of a manifest deviation
What does the cover/uncover + alternate cover test test for?
manifest or latent deviation
What are 4 different ways the cover/uncover + alternate cover tests should be performed?
- With/without glasses
- Near (1/3m) target
- Distance (6m) target
- Non-accommodative
How are ductions and versions into 9 positions of gaze examined?
- ask patient to follow target (usually a pen torch)
- perform cover test in each position
- ask patient to report any diplopia in primary position or during test
How are horizontal and vertical saccades examined?
ask pt to look rapidly between targets postioned at 30 degrees on either side of the midline
How is convergence assessed?
assess to both an accommodative and non-accommodative target
How are horizontal / vertical optokinetic nystagmus examined?
slowly rotate an OKN drum in horizontal and vertical directions
How are ocular deviations classified?
- manifest or latent
- concomitant (constant in all positions of gaze) or incomitant (varying)
What are 2 things to determine for incomitant deviations?
- direction of maximum separate of diplopic images
- type of pattern: neurogenic, mechanical, myasthenic, supranuclear, myopathic
What are 5 types of pathological incomitant deviation pattern?
- Neurogenic
- Mechnical
- Supranuclear
- Myasthenic
- Myopathic
How is Hirschberg’s test performed?
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
What is the normal position of the light reflection in Hirschberg’s test and what does each degree of displacement equate to?
normal = just nasal to centre of cornea
every 1mm deviation represents 7 degrees of 15 prisms
What does it represent if the reflection in Hirschberg test is deflected nasally?
eye is divergent (i.e. exotropic)
What does it represent if the reflection in Hirschberg test is deflected temporally?
eye is convergent i.e. esotropic
Which Purkinje image does Hirschberg test make use of?
1st Purkinje image
What is a second corneal reflection test in addition to Hirschberg test?
Krimsky test
What does the Krimsky test involve?
deviation measured by placing prism bar in front of deviating eye and finding prism strength at which the corneal reflexes are symmetrical
How should the prism be oriented in the Krimsky test?
oriented to point in the direction of deviation i.e. base out for an esotropia, base in for an exotropia
What are the 3 types of cover tests?
- cover-uncover test
- alternate cover test
- prism cover test
What does the cover part of the cover-uncover test test for?
manifest deviation
How is the cover part of the cover-uncover test performed?
- 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
How is the uncover part of the cover-uncover test performed?
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)
What type of deviation does the uncover part of the cover-uncover test reveal?
latent deviation
Why should the cover test be repeat in all 9 positions of gaze? 2 reasons
- to identify the direction of maximum separation of diplopia (indicates direction of paretic muscle action/maximum restriction
- compare ductions and versions
What does the alternate cover test detect?
detects the total deviation (latent and manifest) by causing dissociation of binocular single vision (BSV)
How is the alternate cover test performed?
- 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
In addition to detecting total deviation, what are 2 further things that the laternate cover test can identify?
- dissociated vertical deviation (DVD)
manigest latent nystagmus (MLN)
In what condition are DVD and MLN common?
infantile esotropia
What does the prism cover test measure?
angle of deviation
How is the prism cover test performed?
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
How should the prism be oriented in prism cover test?
pointing in direction of deviation
How do Maddox tests work in in general (rod and wing) and what are they used for?
- involve presenting different images to each eye
- sued for assessing symptomatic phorias
What is a manifest squint?
present when the eyes are open and being used
What is a latent squint?
eye turns only when it is covered or shut
What do Maddox rod vs. wing vs. 2 Maddox rods test for?
- rod = distance
- wing = near
- 2 rods = torsional
How does the Maddox rod test work?
- 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
How is a phoria quantified using a Maddox rod?
finding the prism required to neutralise it
What does it indicate with Maddox rod testing if the line is below the light?
hyperphoria
How is Maddox wing testing performed?
- 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
How is the double Maddox rod test performed?
- 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
Whe will the two lines fuse in the double Maddox rod test?
if there is no residual non-torsional deviation
What is the Parks-Bielschowsky 3-step test used for?
to identify a single underacting muscle in vertical/torsional deviations - particularly useful in superior oblique palsies
What are the 3 steps of the Parks-Bielschowsky 3 step test?
- Perform cover test in** primary position,** identify higher eye
- Perform cover test with gaze to right, then left; identify where separation (and diplopia) is greatest
- Perform cover test with head tilt to right, then left shoulder; identify where separation (and diplopia) is greatest
What are the 3 steps of the Parks-Bielschowsky 3 step test?
- Perform cover test in** primary position,** identify higher eye
- Perform cover test with gaze to right, then left; identify where separation (and diplopia) is greatest
- Perform cover test with head tilt to right, then left shoulder; identify where separation (and diplopia) is greatest
What is step 2 of the Parks-Bielschowky test based on?
eye positionwhere the greatest vertical action occurs - for obliques, this is when eye is adducted; for vertical recti, this is when eye is abducted
What is step 3 of the Parks-Bielschowsky 3-step test based on?
fact that superior muscles intort the eyes, whereas inferior muscles extort
What will the steps of the Parks-Bielschowsky steps each show in right SO underaction?
- R eye higher eye in primary position
- Disparity greatest on gaze to the left
- Disparity greatest on head tilt to the right
What is the interpretation of each possible outcome of the Parks-Bielschowsky 3-step test?
What do caloric tests test?
vestibular/nuclear/infranuclear pathways
In which group of patients can caloric tests be useful?
pts with reduced consciousness
In what position should caloric tests be performed?
head inclined backwards at 60 degrees
How are caloric tests performed and how can the result be interpreted?
water placed in either ear causes nystagmus, with the fast phase as follows: Cold - opposite, warm - same (COWS)
