Paralytic Strabismus



The IIIrd, IVth and VIth nerves supply the extraocular muscles responsible for all eye movements. Lesions affecting the intracranial or intraorbital components of these cranial nerves lead to paralytic strabismus. In addition to the characteristic signs of muscle palsy, associated findings can help localise the site of lesion. Cranial muscle palsies in children tend to be associated with a higher degree of aberrant regeneration than in adults. Nerve palsies secondary to microvascular causes resolve spontaneously within 6 months in the majority of cases.


Sixth nerve Third nerve Fourth nerve Paresis Paralysis Dipolpia 

Supplementary material

Video 7.10

A 42 year old man with a well controlled left hyperphoria in primary position with a slight right head tilt. However, in dextroversion an alternate cover test demonstrates an obvious left hypertropia secondary to significant IO overaction. The deviation almost disappears in laevoversion. There is a small exophoria when tilting the head to the right and left hypertropia when tilting it to the left (MOV 140320 kb)

Video 7.12

Myectomy of the Left Inferior Oblique muscle: the muscle is identified and hooked, lateral to the IR. The muscle belly is held up by two squint hooks and central portion of 1 cm is cauterized at both ends and excised. The cut ends are inspected to ensure there are no residual connecting fibres (MOV 62860 kb)

Video 7.13

The muscle tendon is identified and detached from the sclera as close as possible to the insertion. It is then reattached just lateral to the edge of the IR (MOV 72517 kb)

Video 7.14

The Left eye has two marks put on at the limbus at 0 and 90° to ensure the baseline position is identified. A stay suture is put in, and the eye retracted inferomedially. The SO is identified after hooking the SR, the tendon is split and the anterior 25% isolated on a suture that is advanced 8 mm posterior and 2 mm superior to the LR insertion. Once the procedure is completed the marks show that the eye is now intorted compared to its original position (MOV 245790 kb)

Video 7.16

(MOV 51553 kb)

Video 7.17

A 87 year old patient with a right VIth nerve palsy with a prominent right esotropia that worsens in right gaze with associated loss of abduction (MOV 95257 kb)


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Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Royal Free London NHS Foundation TrustLondonUK

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