Placement 6 learning objectives

Question 1

what are the different types of mechanical strabismus

Answer 1

blow out

browns

duanes syndrome

thyroid eye disease

retinal detachement

myositis

tumours

adherence

CFEOM

Question 1

what are the different types of mechanical strabismus

Answer 1

blow out

browns

duanes syndrome

thyroid eye disease

retinal detachement

myositis

tumours

adherence

CFEOM
§

Question 2

what investigations would be done with a mechanical strabismus

Answer 2

despite the large restriction of movement restriction the deviation in primary position is usually small

so you would assess ocular movements restriction is usually In the opposite direction to the affected muscle and is across the field of action

e.g. blow out restriction in elevation

duction and version movements are usually equally limitedd

intraocular pressure would be raised when looking away from the site of the lesion

force duction - full passive movement unless secondary muscle contracture has occurred

limited passive movement generally in the opposite direction in the lesion sometimes in the same direction or both directions

diplopia - often in reverses

head postures - head up/down in mechanical restrictions

pain in acquired lesions and in some cases of browns syndrome

Question 3

in mechanical deviations what would you expect in relation to saccades, globe position and saccades

Answer 3

overaction of the contralateral synergist only

saccades - normal movement comes to an abrupt end

globe - restriction of the globe when the eye is turned in and the direction in the opposite to the restriction

Question 4

what electricaldiagnositic tests would be used in electromyography

Answer 4

mechanical - increased activity when attempts to look In the direction of the limitation

Question 5

what are examples of neurogenic strabismus

Answer 5

third , 4th , 6th may be unilateral or bilateral

indvidual muscle palsies

Question 6

what would you expect in terms of ocular movements and the deviation upon investigation

Answer 6

deviation - size of the deviation in primary position is dependent on the extent of the paise

ocular movmements - maximum limitation is in the position of the main action of the affected muscle

the amount of movement is greater on duction than version unless there is a complete paralysis

Question 7

what would you expect in terms of the hess , intraocular pressure and forced duction test when investigating

Answer 7

hess - field of affected eye smaller with proportional spacing between inner and outer fields, both fields are displaced according to the deviation

iop- unchanged in all gazes of positons

forced duction - full passive movment unless secondary muscle contracture has occurred

Question 8

what would you expect in relation to diplopia , head posture and pain in relation to neurogenic deviations

Answer 8

in the third nerve , bilateral 6th the direction of the diplopia remains the same

head posture - a combination head posture is common in neurogenic vertical muscle palsies

pain - no pain on movement

Question 9

what would you expect in relation to muscle sequelae , saccades and globe positon in relation to neurogenic deviations

Answer 9

muscle sequelae - full muscle sequelae especially if longstanding

saccades - slowed in the direction of the underaction

globe - no change in the globe position