Clinical characteristics & investigation of neurogenic palsies

Question 1

Concomitant is…

Answer 1

The angle of deviation is the same fixing either eye and in all positions of gaze

Question 2

Incomitant is..

Answer 2

The angle of deviation varies depending on the eye used for fixation and direction of gaze. Caused by:
Neurogenic palsy
Mechanical limitation
Anisometropia

Question 3

Neurological palsies

Answer 3

Nerve supply to muscle affected
May affect one individual muscle or group of muscles
Consider observations and determine further investigations required
Recording of clinical picture to show evidence of recovery, regression, stability

Question 4

Visual acuity

Answer 4

Normal Acuity - usually

Reduced acuity
Previously present e.g old amblyope
Traumatic mydriasis
Related to neurogenic condition e.g retrobulbar neuritis in MS
If recent, can contribute to decompensation of longstanding palsy
Co-incidental pathological cause

Question 5

Position of vertical action

Answer 5

RE LE

SR IO IO SR

IR SO SO IR

Question 6

Muscle actions- SR

Answer 6

Elevation
Intorsion
Adduction

Question 7

Muscle actions - IR

Answer 7

Depression
Extorsion
Adduction

Question 8

Muscle actions- SO

Answer 8

Depression
Intorsion
Abduction

Question 9

Muscle actions- IO

Answer 9

Elevation
Extorsion
Abduction

Question 10

Rad Sin

Answer 10

Recti- adduct
Superior- intort

Question 11

Four considerations when testing

Answer 11

Deviation in the primary position
Fixing with unaffected eye (primary deviation)
Fixing with affected eye (secondary deviation)
Abnormal head posture (compensatory head posture) to avoid deviation

Question 12

Observe AHP for

Answer 12

Head turn
Head tilt
Head elevation / depression
Observe during visual task
Put head straight and observe return to AHP
Look for facial asymmetry – suggests longstanding

Question 13

AHP use

Answer 13

Head turn to place eyes away from action of affected muscle
Head elevation or depression - ditto
Head tilt for:
Vertical – As head tilts e.g. to right – right eye moves up and left eye moves downThus tilt to lower eye to use this
Torsion – As head tilts e.g. to right –right eye intorts and left eye extortsThus if left extorsion is present, tilt right to match fellow eye to that eye position

Question 14

Cover test recording

Answer 14

Record AHP
N.B. Single cover removes reason for AHP Record first with AHP N&D then without AHP
Record Size and Type of deviation

Note-
Degree of incomitance fixing either eye
Difference in vertical deviation between N & D
obliques larger at near
recti larger at distance

Question 15

Q- LSR u/a

Answer 15

Action LSR?

Resultant deviation in p.p?

Position where SR elevates eye – largest u/a here…

Where do eyes want to be to avoid this?……

What’s the AHP?

Question 16

What to observe during OMs

Answer 16

Smoothness of movement during pursuit
Head movements in child may indicate avoidance of affected movement
Pupils
Lid position, changes
Globe position, changes
Nystagmus

Question 17

Underaction

Answer 17

Reduced ocular rotation which improves on testing duction
-BIOS

Question 18

Restriction

Answer 18

Abnormal ocular rotation where the movement does not improve fully when testing ductions
-BIOS

Question 19

Limitation

Answer 19

Abnormal ocular rotation
-BIOS

Question 20

In ocular movements testing assess

Answer 20

versions and ductions and interpret muscle sequelae development

Question 21

Eye movement systems

Answer 21

Smooth pursuit
Saccades
OKN
VOR

Question 22

Do all nerve palsies have BSV

Answer 22

Most commonly normal BSV, or potential for. BUT DO NOT ASSUME

May have previous deviation with suppression or AC, diplopia may occur with change in angle
Traumatic loss of fusion

Question 23

Measurement of binocular function

Answer 23

With / without AHP – latter more repeatable former only possible if longstanding
With /without refractive correction - if indicated
Near / distance
Nine positions of gaze
PCT
Synoptophore
Torsion
Synoptophore
Torsionometer
Double Maddox Rod
Maddox Rod
Subjective where small vertical deviations

N.B. Expected deviation not always found due to a pre-existing deviation

Question 24

Lees screen testing

Answer 24

Measurement of deviation in nine positions of gaze (up to 30°)
Compares one eye to fellow eye
Aids identification of affected eye and muscle
Aids differential diagnosis of neurogenic and mechanical limitations
Illustrates degree of concomitance
Used for monitoring patient
N.B Torsion can only be measured with a special adaptation

Question 25

Can Lees screen be used for bilateral conditions

Answer 25

Not good for bilateral conditions

Question 26

Uses of field of uniocular fixation

Answer 26

Excellent to record the eye movements when ductions are affected
A good representation of eye movements in bilateral conditions and mechanical limitations such as Graves’ orbitopathy

Question 27

Use of measuring field of BSV

Answer 27

Records area in which BSV is maintained
Excellent record of patients symptoms

Question 28

Investigating neurogenic palsies determines

Answer 28

Nerve(s) affected (unilateral or bilateral)
Possible causes
Longstanding or recently acquired
Presence of A or V patterns
Recovery, regression, stability
Need for referral
Management plan