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To describe the clinical features of Duane's retraction syndrome (DRS) in Korean patients.
We retrospectively analyzed the 78 DRS cases that presented to our department between 1995 and 2004. The clinical features investigated included sex distribution, laterality, type of presentation, deviation in primary position, anomalous vertical movements, face turn, amblyopia and anisometropia.
There were 38 (48.7%) affected males and 40 (51.3%) females. Left eye predominance (83.3%) was observed, as was type I presentation (85.9%). Orthotropia was found to be the most common primary position in 46 cases (59.0%). Face turn in unilateral DRS was noted in 13 patients (17.1%). There were 6 cases (7.7%) with anisometropia and 4 (5.1%) with amblyopia.
The clinical manifestations of DRS in our study were different from those of equivalent Caucasian studies yet similar to those previously reported for Asian groups. Racial and regional differences were noted, for which further research is needed to elaborate the reasons and mechanisms.
Duane's retraction syndrome (DRS) is a congenital ocular motility disorder characterized by marked limitation or absence of abduction, restriction of adduction, retraction of the globe, narrowing of the palpebral fissure on adduction, and frequent association with elevation or depression on adduction. This characteristic retraction of the globe is thought to be caused by a branch of the oculomotor nerve innervating the lateral rectus muscle and subsequent co-contraction of the ipsilateral lateral rectus muscle upon oculomotor nerve firing. Three types of DRS have been described by Huber.
Only few reports have investigated DRS patients in Korean patients until now.
This report describes the clinical features of DRS in Korean patients and compares how closely these cases conform to the classic concepts and descriptions.
In this retrospective study, we reviewed the records of 78 consecutive DRS cases presenting to Kim's Eye Hospital between 1995 and 2004. The clinical features analyzed included age at diagnosis, sexual distribution, laterality, type of presentation, deviation at primary position, anomalous vertical movements, face turn, refractive error, amblyopia and anisometropia. Age at first visit, gender, chief complaints, and past medical history were recorded in all cases. All patients underwent a detailed eye examination, including visual acuity determination, manifest and cycloplegic refraction, alternative cover test, duction and version testing, intraocular pressure (IOP) measurement by noncontact tonometry, slit-lamp biomicroscopy and fundus examination.
The clinical type of DRS according to Huber's classification was recorded. The ocular deviation in the primary position of gaze was determined by Hirschberg or Krimsky prism test. Amblyopia was defined as best corrected visual acuity of 20/30 or less in either eye and anisometropia was defined as a difference in cycloplegic spherical equivalent greater than 2.0 diopters (D) between the two eyes. Patients with other non-ocular anomalies or a history of previous ocular surgery, including strabismus correction, were excluded.
Among the 78 cases, the average age at first visit was 9.0 years (2-25 years).
There were 38 (48.7%) affected males and 40 (51.3%) females. The left eye was involved in 65 patients (83.3%) and the right in 11 (14.1%) of the unilateral cases. Two patients (2.6%) showed bilateral involvement (
Based on the Huber's classification, of the 78 affected patients (80 eyes), 67 (85.9%) were classified as type I DRS, 2 (2.6%) as type II, and 9 (11.5%) as type III (
Horizontal alignment in the primary position was determined in all patients. Orthotropia occurred in the majority with 46 patients (59.0%), followed by exotropia in 18 patients (23.1%), and esotropia in 14 (17.9%). Vertical strabismus of hypertropia was associated with exotropia in 3 patients (3.8%), and with esotropia in 2 (2.6%). More than half of those classified as type I were orthotropic and orthotropia was the predominating alignment among type III patients. Both individuals with bilateral DRS were esotropic. Those with type I and III (57.7%) tended to be orthotropic (
Anomalous vertical movements, including upshoots and downshoots which are a prominent feature of DRS, were found in 12 cases (15.4%): 9 (13.4%) of 67 type I patients, both (100.0%) of 2 type II patients and 1 (11.1%) of 9 type III patients (
Face turn in unilateral DRS occurred in 13 eyes (17.1%): 12 (18.5%) type I cases, one (50.0%) type II case and zero (0%) type III cases (
Among 78 patients who underwent cycloplegic refraction, 14 cases (18.0%) were emmetropic, 33 (42.3%) were hypermetropic and 31 (39.7%) were myopic. Six cases (7.7%) were anisometropic and 4 (5.1%) amblyopic.
DRS reported among the white population is usually a sporadic syndrome with a unilateral predominance for the left side and with a slight female predominance. In most cases the abducens nucleus and nerve are absent or hypoplastic, and the lateral rectus muscle is innervated by a branch of the oculomotor nerve. However, there may also be contributing mechanical abnormalities.
In our study, most of the 78 patients complained of limitation of ocular movement, ocular deviation and abnormal head position. The average age of first visit was 9 years old.
The proportion of males (48.7%) and females (51.3%) was similar in our study, which is in contrast to the female predominance of previous reports by Duane,
Also, our findings corroborate Lee and Chang's study
According to Huber's classification, Raab
Many patients with DRS appeared to have strabismus in the primary position. Patients might adopt a small, unnoticed, head position movement which could obscure a small angle strabismus in the primary position in order to achieve binocular single vision. Among the 85 patients with unilateral DRS reported by Isenberg and Urist,
The occurrence of face turn, a major characteristic of this entity, is usually attributed to maintenance of straight eyes and fusion. For face turn and anomalous vertical movements of DRS eyes, Raab
Most unilateral DRS patients who showed esotropia and exotropia were found to have face turn, which is a mechanism of maintaining binocular single vision whereby the face is turned toward the direction of the horizontal muscle with the greatest deficit. Our study revealed this tendency, as had many other Caucasian and Asian studies.
Regarding the relationship of face turn in primary orthotropia with upshoots and downshoots in unilateral DRS, 4 (66.7%) of the orthotropic DRS cases exhibited face turn toward the side of limited abduction, affected eye. However, two cases (33.3%) with severe upshoots and downshoots tended to turn their faces away from the side of vertical deviation.
In our study, we found emmetropia in 14 cases (18.0%), hypermetropia in 33 (42.3%), and myopia in 31 (39.7%). Zhang
Various reports have compared the occurrence rate of amblyopia in the general population with that in DRS. In our study, there were 4 cases (5.1%) with amblyopia, compared to 4 of 46 (8.0%) for Lee and Chang,
In conclusion, although most clinical manifestations of DRS in this study corresponded with previous studies among Caucasians and Asians, the male/female distribution rate and Huber's classification were different from Caucasian studies but similar to Asian ones. Further research is necessary into the racial and regional differences found in clinical features of DRS.
Sex and laterality distribution in Duane's retraction syndrome
Distribution of clinical types in Duane's retraction syndrome
Primary position alignment in Duane's retraction syndrome
Face turn and anomalous vertical movements in Duane's retraction syndrome
AVM: Anomalous vertical movements, FT: Face turn, The percentage of face turn was calculated among patients after exclusion of the two bilateral cases.
Face turn in patients with unilateral Duane's retraction syndrome
*with respect to the affected side
The association of face turns in primary orthotropia with upshoots and downshoots in unilateral Duane's retraction syndrome