Duane Retraction Syndrome
(DRS)
This condition was originally described at the end of the 19th century. In 1905 Duane described 54 cases, summarized all the clinical findings, reviewed previous work, and offered theories on pathogenesis and treatment.
DRS more frequently occurs in the left eye than in the right, and in females more than in males. Bilateral involvement is less frequent than unilateral occurrence. In several large series, the ratio of right eye to left eye involvement was 1:3, the prevalence of bilaterality was 20 per cent, and there was a slight preponderance of females over males (54 per cent versus 46 per cent). This condition is found in approximately 1 per cent of individuals with strabismus.
Clinical Manifestations The most characteristic clinical findings in DRS include an absence of abduction of an eye with slight limitation of adduction, retraction of the globe in attempted adduction, and up- and downshooting, or both in adduction. Huber, with the support of electromyography, provided a useful classification of DRS into three types:
Type I. Marked limitation or complete absence of abduction, normal or only slightly restrict adduction, narrowing of the palpebral fissure and retraction of the globe on adduction, and widening of the palpebral fissure on attempted abduction. Electromyography shows absence of electrical activity in the lateral rectus muscle on abduction, but paradoxic electrical activity on adduction.
Type II. Limitation or absence of adduction with exotropia of the affected eye. Normal or slightly limited abduction. Retraction of the globe on attempted adduction. Electromyography reveals electrical activity of the lateral rectus muscle on both abduction and adduction.
Type III. Severe restriction of both abduction and adduction. Retraction of the globe and narrowing of the palpebral fissure on attempted adduction. Electromyography demonstrates electrical activity of both horizontal rectus muscles on both adduction and abduction.
Type I is most common, followed in order of frequency by Types II and III. Most patients with Type I DRS have straight eyes in the primary position during infancy and childhood. Some children develop an increasing esodeviation in the primary position and adopt a compensatory head turn toward the side of the involved eye to maintain normal binocular vision.
Pathogenesis Although DRS has been well described clinically, the etiology remains unclear. Various theories have been formulated on the basis of data collected from surgical, electromyographic, and autopsy studies.
Treatment Before surgery is contemplated, coexisting significant refractive errors, anisometropia, and amblyopia must be treated. Kirkham found that amblyopia was present in 20 per cent of his DRS patients, and nearly 50 per cent had anisometropia. In two other large series of the incidence of amblyopia in DRS patients was 10 and 14 per cent, respectively. However, Mauro and co-workers found a 3.6 per cent prevalence of amblyopia among 220 patients with DRS. Tredici and von Noorden also noted a 3 per cent incidence of amblyopia in their 72 patients, and commented that this incidence is similar to that in the general population.
Indications for surgery for patients with DRS are a significant
deviation in primary position, an anomalous head position, a large
upshoot or downshoot or retraction of the globe that is cosmetically
intolerable.