A 25-year-old patient presents complaining of a longstanding right inward eye turn and problems looking to one side. She denies any double-vision and remembers being examined by eye specialists when she was a child. She is curious if there have been any developments in treatment for her eye turn. On motility testing, her right eye has a limitation of moving out (ABDuction) with less marked limitation of looking into her nose (ADDuction). Her right eyelids become wider and narrower as she moves her eyes. What is going on?
Whenever I see eyelids widen and narrow as the eyes move, the first thing that comes to my mind is Duane’s retraction syndrome. This is caused by innervation of the lateral rectus muscle by an abnormal branch of the inferior division of the third cranial nerve because of underdevelopment (hypoplasia) or failure of development (aplasia) of the sixth nerve nuclei. This occurs because of disruption in embryological development between 8th and 12th week of pregnancy.
This means that when the third cranial nerve activates the medial rectus to pull the eye towards the nose at the same time it activates the lateral rectus, which pulls the eye towards the temple. Pulling the eye in both directions means it is pulled into the orbit causing the retraction and the narrowing of the eyelids. There are three types of Duane’s retraction syndrome:
- Limitation of ABDuction with less marked limitation of ADDuction.
- May have associated esotropia.
- Widening of palpebral fissure on ABDuction narrowing and globe retraction on ADDuction.
Looks to me as if the patient described above has Type A Duane’s retraction syndrome.
- Limitation of ABDuction.
- Normal ADDuction.
- May be associated with esotropia.
Widening of palpebral fissure on ABDuction, narrowing and globe retraction on ADDuction.
- Limitation of ADDuction and ABDuction (limitation of ADDuction > than ABDuction).
- Usually exotropic.
- Globe retraction on ADDuction and in rare cases on ABDuction.
- If BSV good and cosmetically acceptable CHP then observe only.
If there are neck problems or poor appearance then extraocular muscle surgery to enhance ABDuction ability may help. In this patient’s case if her right inward eye turn negatively affects her appearance a referral to an ophthalmologist to be considered for surgery would be useful.