Abstract
Purpose :
In patients with Duane syndrome (DS), we often observe depression of the affected eye in attempted abduction, yet the phenomenon has not been well characterized in the literature. We therefore retrospectively reviewed existing clinical images of patients with esotropic DS to characterize vertical deviations in abduction and identify clinical associations.
Methods :
Search of Boston Children’s Hospital billing records (2002-2015) was performed to identify all patients diagnosed with unilateral or bilateral DS. Exclusion criteria included previous strabismus surgery or absence of adequate clinical images. (At our center, it is standard practice to obtain clinical images of strabismus.) Images were then reviewed independently by 3 ophthalmologists to assess vertical alignment in attempted abduction. Eyes were assigned into one of 3 groups: Midline group (no vertical deviation in attempted abduction), Depression group (downward deviation in abduction), and Elevation group (upward deviation). Statistics: Kruskal-Wallis test with post-hoc analysis (Dunn procedure) for continuous data; Fisher exact test for categorical data.
Results :
A total of 484 patients with DS were identified;113 unilateral DS and 25 bilateral DS patients met inclusion criteria. In unilateral patients, 36 (31.9%) were in the Midline group, 74 (65.5%) in the Depression group, and 3 (2.7%) in the Elevation group. There was more abduction limitation in the depression group (-4) than in the midline group (-3) (P=0.01). Median vertical deviation in abduction was more severe in the elevation group than in the depression group (P=0.003). In bilateral DS patients, group assignment for one eye did not correlate with assignment for the fellow eye in 50%.
Conclusions :
The majority of patients with esotropic DS demonstrate depression of the affected eye in attempted abduction. The phenomenon is associated with more severe abduction limitation. We believe that this is another form of dysinnervation in DS, either from increased innervation to the inferior rectus muscle or decreased innervation to the superior rectus muscle. Depression in abduction should be noted, especially when planning for surgery in DS. Futures studies should investigate the contribution of the phenomenon to unexpected post-op vertical deviations.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.