Clinical Features of Duane Retraction Syndrome: A New Classification

PURPOSE: We sought to provide a new classification system for Duane retraction syndrome (DRS) according to type and angle of strabismus during primary gaze and to analyze the clinical features of each DRS type. METHODS: The medical records of 65 DRS patients who visited the department of pediatric ophthalmology at Seoul National University Children's Hospital between 2010 and 2017 were retrospectively analyzed. Patients whose angle of exotropia at primary gaze exceeded 3 prism diopters (PDs) were classified as “Exo-Duane,” those whose angle of strabismus at primary gaze did not exceed 3 PDs were classified as “Ortho-Duane,” and those whose angle of esotropia at primary gaze exceeded 3 PDs were classified as “Eso-Duane.” RESULTS: Among 65 DRS patients, Ortho-Duane was the most common (53.8%) type, followed by Eso-Duane (33.8%) and Exo-Duane (12.3%). The mean age at diagnosis was significantly higher in the Exo-Duane group than the Ortho-Duane or Eso-Duane group (p = 0.003 and p < 0.001, respectively). A predominance of left eye involvement was observed in the Ortho-Duane (62.9%) and Eso-Duane (90.9%) groups. The frequencies of upshoot, downshoot, fissure narrowing, and globe retraction were not significantly different among the subgroups. Head-turn was more frequent in Eso-Duane patients than in Exo-Duane or Ortho-Duane patients (p = 0.001 and p < 0.001, respectively). Myopia accounted for the most common refractive error among Exo-Duane patients (71.4%), while hyperopia was found more often in both Ortho-Duane (64.7%) and Eso-Duane (85.0%) patients. The majority of patients showed gross stereoacuity (93.1%), and a large proportion had good stereoacuity (Exo-Duane 60.0%, Ortho-Duane 81.3%, Eso-Duane 87.5%). CONCLUSIONS: Our newly proposed classification of DRS according to type and angle of strabismus at primary gaze was practically useful and showed potential for use as an objective guideline in the clinical setting.