What are the typical features of Duane's Syndrome?
Video Transcript:
Duane's Syndrome is a type of squint that is present from birth. It is caused by an abnormality of the nerve supply to the lateral rectus muscle. As a result of this abnormality the lateral rectus muscle does not receive a signal from its nerve “telling it” to contract when the child attempts to move the eye outwards.
Duane’s Syndrome usually affects one eye, but can affect both eyes. It is more common in girls and occasionally there may be a family history of Duane’s Syndrome.
What are the features of Duane’s Syndrome?
- - Reduced outward movement of the affected eye
As a result of its abnormal nerve supply the lateral rectus muscle does not function normally and the eye is unable to move outwards.
- - A convergent squint
The majority of children with Duane’s Syndrome have a convergent squint when they are looking straight ahead, but most are able to compensate for this squint by turning their head slightly to the affected side. By adopting this head posture they are able to keep their eyes straight and this is why children with Duane’s Syndrome usually develop good vision in both eyes and have good stereopsis.
- - Retraction of the eye on looking inwards
When the affected eye moves inwards a signal is sent not only to the medial rectus muscle, but also to the lateral rectus muscle.’ This causes both muscles to contract at the same time and results in the eye being pulled further back into the eye socket. This will also cause some limitation of the inward movement of the eye.
Parents often describe the eye as appearing “smaller” when the child looks to the opposite side, because the upper eyelid falls to a lower position as the eye moves backwards into the eye socket. Conversely, the eye also appears bigger when the child attempts to look outwards.
- - Up shoots or down shoots of the eye
The abnormal contraction of the lateral rectus can also cause the eye to shoot upwards or downwards when the child tries to look inwards.
- - A divergent squint
If there is a lot of abnormal contraction of the lateral rectus muscle the eye can actually be in a divergent position.
