Nadia Northway

Deviation varies with size and or direction of gaze

In truth nearly all forms of strabismus are incomitant to a degree but clinically there is usually more than 5o difference before incomitancy is noted.

C l a s s i f i c a t i o n

N e u r o g e n i cT h i r d n e r v e p a l s y

F o u r t h n e r v e p a l s yS i x t h n e r v e p l a s y

M e c h a n i c a lB r o w n ' s S y n d r o m eD u a n e ' s S y n d r o m e

C o n g e n i t a l

C l a s s i f i c a t i o n

N e u r o g e n i cT h i r d n e r v e p a l s y

F o u r t h n e r v e p a l s yS i x t h n e r v e p l a s y

M e c h a n i c a lB r o w n ' s S y n d r o m eD u a n e ' s S y n d r o m e

R a r e

M y o g e n i cD y s t h y r o i d E y e d i s e a s e

M y a s t h e n i a G r a v i s

A c q u i r e dA d u l t s a n d c h i l d h o o d

Vascular affects all nerves equally Head trauma more commonly affects IVth

nerve but may affect all Aneurysm most commonly affects IIIrd nerve Neoplasm Unknown Other

Diabetes Thyrotoxicosis Hypertension Aneurysm Giant cell arteritis Multiple Sclerosis Myasthenia Gravis

History and symptoms External Examination Cover test Motility Ophthalmoscopy Fields

Diplopia Abnormal head posture-chin, turn and tilt Acuity Associated symptoms General health Injury

Strabismus Lid position Injury- chemosis, oedema Proptosis Pupils Asymmetry

Always turn in direction of action of palsied muscle e.g. LMR palsy will turn to right

Always move chin in direction of action of palsied muscle e.g. LSR palsy will elevate chin

Always tilt to lower eye

Small deviation in primary position may indicate very recent onset < 36 hours or mechanical problem

In palsy- will be greater when fixing with the affected eye and usually larger size of deviation

Know muscle actions Take patients eyes into extremes of gaze Use objective and subjective assessment-

corneal reflexes and CT. Do not rely on pt reporting diplopia since suppression or poor VA may affect results.

Hess chart and diplopia chart.

RAD SIN- recti adduct and superiors intort Recti muscles pull the eye in the direction of

their name in the abducted position Obliques push the eye in the direction

opposite to their name in the adducted position

Original palsy Overaction of the contralateral synergist Overaction of the ipsilateral antagonist Inhibitional palsy

This applies to neurogenic palsy and after all stages of sequelae have occurred concomitancy is achieved

SR

LR

IO IOSR

MR

SOSOIR

LR

Overaction of contralateral synergist only Left Brown’s syndrome overaction of right

superior rectus is seen

Look for smallest field to identify affected eye Look at center circle to determine deviation in

primary position Look for area with greatest deflection to

identify affected muscles

Used to differentiate between SR and SO palsy Muscle sequelae identical In left SO palsy deviation will increase when

head tilted to left due to unopposed action of the LIO

Complete or partial Rare to find individual muscles affected but

Congenital SR palsy quite common May also be multiple muscle involvement

including pupil and ciliary body

Hypotropia of affected eye and may be slightly exo

Chin elevation Can be longstanding -usually have enlarged

fusion range and some suppression

Hypertropia in primary position

Hypotropia in primary position with possible slight eso.

Exo deviation

Exotropia with hypotropia, ptosis and possible dilation of pupil and accommodation palsy

Esotropia which is greater on distance fixation

Hypertropia with slight eso , eye also extorted, greater at near

Small devation in primary position but hypotropia of affected eye on elevation in adduction

May be hypotrpia or hypertropia Infraorbital anaesthesia Chemosis Vertical diplopia Restricted eye movement in upgaze and

downgaze

Wet phase when muscles swell -myogenic Dry phase when eye movement restrictions

become mechanical in characteristics Muscles affected - IR MR SR rarely LR Proptosis or exophthalmos Check Fields Lid retraction and lid lag

Mechanical Small deviation in pp Ductions and

versions equal Ceasing of

movement abrupt Pain Reversal of diplopia Upshoots and

downshoots

Neurogenic Large deviation in pp Ductions better than

versions Gradual failure of

movement No pain No upshoots and

downshoots

Differentiation of mechanical and neurogenic palsy

• Mechanical• Muscle sequelae- only

overaction of contra syn

• Hess chart -pointed field which look squashed

• Neurogenic• Full muscle sequelae• Smoother filed on

Hess

Longstanding AHP - fixed and pt

usually unaware No diplopia Enlarged fusion

ranges Old photographs Gradual onset of

symptoms usually Amblyopia Suppression

Newly acquired Pt aware of AHP and

uncomfortable Diplopia Sudden onset No enlarged fusion

range

Differentiate SR and SO palsy

• SO• Eso deviation more typical• AHP - chin depression• V eso pattern

• Greater vertical deviation at near

• Bielchowsky +ve• Diplopia greatest on

depression

• SR• Exo deviation more

typical• AHP- chin elevation• V exo pattern

• Greater deviation in distance

• Bielchowsky -ve• May have history of ptosis• Diplopia greatest on

elevation

Sudden onset diplopia Incomitant deviation previously unidentified Uncomfortable head posture Patient has localisation disturbance Patient symptomatic Other signs and symptoms