Duane syndrome (Duane retraction syndrome): causes, signs and management

Six muscles around each eye, controlled by three nerves, move the eyes in different directions. In Duane syndrome the movement is limited when looking to one or other side. The usual description is an eye that cannot move fully outwards, towards the ear, or inwards, towards the nose, or both to varying degrees.

A distinctive feature that both NHS sources mention is that the affected eye can look smaller as it moves towards the nose and larger when it moves outwards. The eye appears to pull back, or retract, into the socket, which is where the name retraction syndrome comes from. Hull University Teaching Hospitals says it is commonly seen to affect the left eye and occurs more often in females than males.

It can also be associated with a turn of one eye when looking straight ahead, known as a squint (strabismus). Some children also need glasses.

The most notable theory, according to Hull, is a "miss-wiring" of the nerves to the eye muscles, due to lack of development of the sixth cranial nerve that supplies the lateral rectus muscle, which pulls the eye outwards. Other theories suggest a thin, tight or inelastic eye muscle is responsible.

The Bedfordshire and Luton service adds that it is difficult to find the exact cause for an individual child and lists an eye muscle not working properly, an eye muscle attached in the wrong place, or a nerve not working properly as possibilities. It also says the syndrome is usually present at birth but can develop from an injury to the face or facial surgery.

Nothing a parent did or did not do in pregnancy or early life is described as causing this condition by either source.

The Bedfordshire and Luton service says parents often notice when one eye does not move outwards properly and may see their child turn their head to look at books or the television, because the child is adjusting for the lack of movement in one direction.

• One eye that does not follow a toy or a face fully to one side.

• A face turn or a tilted head to look at things.

• An eye that seems to narrow or sink back as it turns inwards.

• A squint in the straight-ahead position, which may come and go.

• Complaints of discomfort when looking to the sides, or a preference for turning the whole head rather than the eyes.

In the UK, children with a suspected eye movement problem are usually seen by an orthoptist, often at a hospital eye department or a community children's eye service, and sometimes by an ophthalmologist as well. The assessment looks at how the eyes move in all directions, whether there is a squint, how well each eye sees and whether glasses are needed.

A GP or health visitor can refer a child when parents are worried, and school or nursery vision screening may flag a problem. Because the condition is usually stable, tests are mostly clinical and do not involve scans or blood tests.

Hull says treatment is generally not required unless there is an associated squint or a need to wear glasses. Bedfordshire and Luton says that if the orthoptist finds a reduction in vision, glasses and eye patches will be recommended, and children will need regular orthoptic check-ups to make sure vision is good in both eyes and the eyes work together.

Hull explains that surgery may be considered if the squint is large and/or the head posture is large and uncomfortable. This would only be in marked cases and would be discussed with the ophthalmologist. In general, surgery aims to improve the position of the eyes or the head turn, rather than to restore full movement.

Hull suggests it may be helpful to inform a child's teacher about the condition so consideration can be given to the child's position in the classroom. Teachers can help by not discouraging any head posture and by seating the child on the side of the room that lets them turn their head comfortably and keep good vision.

Children with Duane syndrome generally take part in the same activities as their classmates. Parents can encourage a child to keep up with eye appointments, and to say if looking at the board or screen becomes tiring. Adults who were diagnosed in childhood can usually carry on as normal and should mention the diagnosis at eye tests.

Duane syndrome is present from early life and is not an emergency. A new or sudden change in eye movement, a new double vision, a drooping eyelid, a headache with vomiting or any eye problem that appears suddenly after an injury should be assessed urgently, because these can have other causes. Contact the GP, NHS 111 or an eye casualty department, or call 999 if there are signs of a stroke or a head injury with drowsiness.

Parents who have simply noticed an eye that does not move fully to one side should ask for an orthoptic assessment rather than waiting to see whether the child grows out of it.

On the NHS, orthoptists and ophthalmologists see children through hospital eye departments and community children's eye services after a GP, health visitor or optometrist referral. Orthoptic reviews are the usual long-term follow-up.

Some families choose a private paediatric ophthalmologist for an earlier appointment or a second opinion before surgery. The underlying assessment is the same, and many families use both routes at different points.