Simultaneous contraction of the medial and lateral rectus muscles results in Duane Retraction Syndrome (DRS). The presence of a familial pattern in some cases suggests an autosomal dominant mode of transmission. Despite the variable presentation of this syndrome, its cause remains unclear. Describing the potential factors contributing to DRS in monozygotic twins may be effective in explaining its etiology. We report a unique case of monoamniotic monozygotic twins case both 7-year-old Iranian girls with DRS type I, inherited from their 36-year-old father with DRS type III. There was no clinical manifestation of DRS in the 38-year-old Iranian mother. One twin exhibited bilateral DRS, whereas the other manifested DRS exclusively in the right eye. In contrast, their father had DRS limited to the left eye. The unique laterality discordance in monozygotic twins emphasizes the role of gene expression patterns in the variability of DRS. These findings highlight the complex nature of clinical expression of DRS. Furthermore, we recognize the need to consider additional factors, such as placental dynamics, the environment, epigenetic modifications, and vascular development, for a comprehensive understanding of this condition. While genetic factors may play a fundamental role in understanding DRS in twins, it is important to consider the interaction of placental, environmental, epigenetic, and vascular developmental factors for a comprehensive approach.

Congenital cranial dysinnervation disorders (CCDDs) are a group of rare, nonprogressive conditions characterized by abnormal development of the cranial motor nerves and variable ocular motility deficits, ptosis, incomitant strabismus, and facial palsy. Advances in genetics and neuroimaging have revealed that these disorders result from defects in neuronal differentiation or axon guidance of the cranial motor neurons. Duane retraction syndrome, the most common CCDD, results from the absence of the abducens nerve and innervation of the lateral rectus by oculomotor nerve axons; causative genes include CHN1, MAFB, HOXA1, SALL4, and EBF3, although most cases do not have a genetic diagnosis. Congenital fibrosis of the extraocular muscles (CFEOM), results from variants in KIF21A, PHOX2A, TUBB3, or other tubulin genes, and affects the oculomotor and trochlear nerves. Horizontal gaze palsy with progressive scoliosis (HGPPS), caused by ROBO3 loss of function, arises from failure of axonal midline crossing in the brainstem. Moebius syndrome, defined by abducens and facial nerve palsies, has no identified genetic cause and may result from non-Mendelian causes. Additional CCDDs with atypical or syndromic presentations are linked to COL25A1, ECEL1, and ACKR3, although many do not have a genetic explanation. The expanding list of CCDD-associated genes highlights shared developmental pathways, including neuronal differentiation, axon guidance, and microtubule dynamics. Improved genetic diagnosis informs prognosis and multidisciplinary management. This review synthesizes current understanding of CCDDs, emphasizing the shift from phenotypic classification to molecular subtyping, and underscores the importance of ongoing research to resolve genetically unsolved cases and refine diagnostic and therapeutic strategies.

To study the clinical profile and surgical outcomes of patients with bilateral Duane syndrome with exotropia. The records of all consecutive patients diagnosed with bilateral Duane syndrome with exotropia in primary gaze (2010-2024) were reviewed. Patient demography, age at presentation, and type of Duane syndrome were studied in the clinical profile. The pre-operative and post-operative details of angle of deviation, abnormal head posture, horizontal ocular ductions, grade of globe retraction, and overshoot were evaluated for the surgical outcomes. Forty-five patients (male, 51%) were diagnosed with bilateral Duane syndrome with exotropia, of which 38% underwent surgical correction. The mean age at presentation was 18.06 ± 12.08 years. Of the total, 37% were emmetropic and 29% amblyopic. Bilateral type 3 Duane syndrome (49%) was the most common presentation. The mean pre-operative deviation for distance and near was 29.84 ± 17.73Δ and 32.49 ± 18.44Δ, respectively. The mean change in angle of deviation post-operatively for distance and near was 23 ± 5Δ and 26 ± 5Δ, respectively. The average angle of deviation at the final follow-up for distance was 8 ± 12Δ and near 12 ± 12Δ. Surgical success for primary position deviation, abnormal head posture, globe retractions, and overshoots was achieved in 59%, 86%, 57%, and 50% patients, respectively. Bilateral type 3 is the most common bilateral Duane syndrome with exotropia. Individualized surgical management (algorithm) ensures optimal alignment and head posture correction.

Identifying and managing ocular causes of abnormal head posture (AHP) in children is crucial, as early intervention may not only improve visual function but also prevent the development and progression or even resolve facial asymmetry. The effect of early AHP treatment on halting the development of facial asymmetry, or even eliminating or decreasing it with age, has not yet been evaluated. In this prospective observational study, the quantitative and qualitative facial asymmetry of paediatric patients with superior oblique palsy (n = 8, 53.3%) and Duane retraction syndrome (n = 7, 46.7%), who had AHP and underwent strabismus surgery, was assessed before and five years after the operation. Captured photographs of the face were analysed by CorelDRAW Graphics Suite X7 software to calculate the relative facial size (RFS) and facial angle as well as evaluate hemihypoplasia, columella deviation, one-side cheek and nostril compression. The median preoperative age was 4.5 years (IQR 2.5; range 1-5 years). Preoperative facial asymmetry in 14 (93.3%) patients decreased to 10 (66.7%) postoperatively. On evaluating quantitative facial asymmetry parameters pre- and postoperatively, the median facial angle changed from 0.36° (IQR 1.96°) to 0.00° (IQR 1.37°), and the median RFS changed from 1.006 (IQR 0.031) to 1.000 (IQR 0.019). Before surgery, hemihypoplasia, one-side cheek and nostril compression, and columella deviation were observed in 10 (66.7%), 8 (53.3%), 9 (60.0%), and 2 (13.3%) cases, respectively. Following surgery, there was a reduction of 20.1% in one-side face, 46.6% in cheek, and 46.7% in nostril compression. The frequency of one-side cheek and nostril compression was significantly decreased following surgery (p = 0.011 and p = 0.012, respectively). Timely strabismus intervention for the treatment of AHP may help enhance facial symmetry in children. However, as this was an observational study without a control group, a causal relationship cannot be established. Duane retraction syndrome, previously known as Stilling-Turk-Duane syndrome, is caused by the absence or partial development of the abducens nucleus and nerve. As a result, there is aberrant innervation of the lateral rectus by the oculomotor nerve. Similar developmental anomalies of 1 or more cranial nerves have come to be grouped under congenital cranial dysinnervation disorders. These anomalies may be termed primary due to the absence of normal innervation or secondary following aberrant innervations from other cranial nerves. The evaluation and management of Duane retraction syndrome can be very challenging, and a judicious approach is essential. Duane retraction syndrome is a rare, congenital ocular motility disorder characterized by limitation or absence of horizontal eye movements, globe retraction, and narrowing of the palpebral fissure on attempted adduction. First described by Alexander Duane in 1905, this condition represents approximately 1% to 4% of all cases of strabismus. The pathophysiology is now understood to involve a congenital cranial dysinnervation disorder, in which aberrant innervation of the lateral rectus muscle by branches of the oculomotor nerve leads to paradoxical co-contraction of horizontal recti. Although classically unilateral, Duane retraction syndrome may be bilateral in 10% to 20% of cases and is more commonly observed in females, with a predilection for the left eye. The etiology is linked to developmental anomalies of the abducens nerve (cranial nerve VI) or its nucleus, resulting in absent or hypoplastic innervation and compensatory miswiring from the oculomotor nerve. This neurogenic origin is supported by magnetic resonance imaging (MRI) studies demonstrating absent abducens nerve and by electromyography (EMG) findings of simultaneous lateral and medial rectus contraction during attempted adduction. In some cases, Duane retraction syndrome is associated with systemic anomalies such as Goldenhar syndrome, Klippel-Feil anomaly, or other congenital malformations, reinforcing the notion of a broader embryologic insult affecting cranial nerve development. Clinically, Duane retraction syndrome is classified into 3 primary types according to Huber's classification (1974): Type I: Marked limitation or absence of abduction, with relatively normal adduction and globe retraction on adduction. Type II: Limitation or absence of adduction with relatively normal abduction. Type III: Limitation of both abduction and adduction, often with significant globe retraction. Patients may also exhibit upshoots or downshoots on adduction due to leash effects or mechanical factors within the extraocular muscle pulleys. Abnormal head posture is common as patients adopt compensatory face turns to maintain binocular single vision in primary gaze. The severity of motility restriction and retraction varies widely, influencing both functional and cosmetic concerns. Epidemiologically, Duane retraction syndrome accounts for a small fraction of strabismus cases worldwide but carries substantial clinical importance due to its distinct presentation, surgical challenges, and potential associations with systemic disorders. Population-based studies indicate prevalence rates ranging from 0.1 to 0.7 per 1000 live births, though true incidence may be underestimated due to underdiagnosis in mild cases. Awareness among pediatricians, ophthalmologists, and orthoptists is critical for early recognition and evaluation. From a diagnostic standpoint, Duane retraction syndrome is primarily a clinical diagnosis supported by a detailed ocular motility examination. Key signs include narrowing of the palpebral fissure on adduction, globe retraction, and variable upshoots or downshoots. Forced duction testing may reveal mechanical restrictions, but the hallmark finding is paradoxical co-contraction of horizontal recti, confirmed by EMG. Imaging with high-resolution orbital MRI or diffusion tensor imaging can delineate the absence of the abducens nerve, providing objective confirmation and aiding in surgical planning. Assessment should also include evaluation for associated systemic anomalies, as up to 30% of patients may have other congenital malformations. Management of Duane retraction syndrome is individualized and guided by the severity of motility limitation, presence of abnormal head posture, and patient symptoms. Mild cases with good primary gaze alignment may require only observation and periodic follow-up. Surgical intervention is indicated for significant misalignment in primary gaze, large abnormal head posture, or cosmetically disturbing globe retraction and upshoots or downshoots. Procedures may include recession of the medial rectus, lateral rectus, or a combination, as well as vertical rectus transpositions in selected cases. The surgical approach is often more complex than in other forms of strabismus due to the paradoxical innervation and risk of exacerbating globe retraction. Overcorrection, induced vertical deviations, and persistent limitation are recognized challenges. Duane retraction syndrome is nonprogressive, but long-term follow-up is essential, particularly in children, to monitor ocular alignment, binocular function, and amblyopia risk. Amblyopia occurs in up to 10% of cases, necessitating prompt detection and treatment. Orthoptic therapy plays a supportive role in maintaining binocular vision and managing mild head postures, although it does not correct the underlying innervational anomaly. Recent advances in understanding Duane retraction syndrome pathogenesis have emerged from genetic and neuroimaging studies. Mutations in genes such as CHN1 (encoding alpha2-chimaerin) have been identified in familial cases, implicating axon guidance defects in cranial nerve development. These findings place Duane retraction syndrome within the broader category of congenital cranial dysinnervation disorders, alongside Möbius syndrome and congenital fibrosis of the extraocular muscles. This reclassification has shifted the focus from purely mechanical explanations to neurodevelopmental mechanisms, fostering novel research avenues. The psychosocial impact of Duane retraction syndrome should not be underestimated. Visible eye movement anomalies and abnormal head posture can affect self-esteem, social interactions, and quality of life, particularly in adolescents. Counseling, patient education, and appropriate referral for psychological support may be beneficial in selected cases. In pediatric patients, parental reassurance and guidance are critical to alleviate anxiety and ensure adherence to follow-up schedules. Interprofessional collaboration is central to optimal Duane retraction syndrome management. Pediatric ophthalmologists, orthoptists, neurologists, radiologists, and genetic counselors all contribute to comprehensive evaluation and care. For example, neurologists may assess for associated cranial nerve or central nervous system anomalies, whereas genetic counselors provide insight into inheritance patterns and recurrence risks. Radiologists skilled in high-resolution orbital imaging play an important role in confirming diagnosis and guiding surgical strategy. Orthoptists assist with functional assessment, prism adaptation, and post-operative rehabilitation, enhancing overall outcomes. In conclusion, Duane retraction syndrome represents a distinct, nonprogressive congenital ocular motility disorder with complex neurogenic and mechanical features. Advances in neuroimaging and genetics have enriched our understanding of its pathophysiology, whereas surgical and non-surgical management strategies continue to evolve. Early recognition, thorough evaluation for systemic associations, individualized treatment planning, and long-term multidisciplinary follow-up are key pillars in optimizing functional and cosmetic outcomes for patients. This activity equips learners with an evidence-based, clinically relevant framework for diagnosing and managing Duane retraction syndrome, integrating current guidelines, expert consensus, and interprofessional care principles to improve patient-centered outcomes. Bielschowsky coined the term dissociated vertical deviation (DVD). DVD has also been referred to as “alternating hyperphoria,” “double hyperphoria,” “occlusion hyperphoria,” “occlusion hypertropia,” “periodic vertical deviation,” “alternating sursum-duction,” “double dissociated hyperphoria,” “dissociated hypertropia,” and “dissociated vertical divergence.” DVD is classically defined as vertical drifting of one eye when the patient fixates at a target with the other eye. The deviation is often bilateral and asymmetrical.  This usually manifests when there is a mechanical, optical, or sensory interruption of the binocular visual input. The DVD syndrome encompasses 3 components: hyperdeviation, abduction, and excyclotorsion. The deviation may manifest spontaneously when the patient is fatigued, daydreaming, or latent, manifesting only on cover-uncover or alternate cover tests. An interesting finding is that as the uncovered/deviated eye shifts downwards to take up the fixation, the eye fixing earlier does not show a corresponding downward shift, thus violating the Herring law. Duane Retraction Syndrome (DRS) is a rare, congenital ocular motility disorder characterized by limitation or absence of horizontal eye movements, globe retraction, and palpebral fissure narrowing on attempted adduction. First described by Alexander Duane in 1905, this condition represents approximately 1% to 4% of all cases of strabismus. The pathophysiology is now understood to involve a congenital cranial dysinnervation disorder (CCDD) in which aberrant innervation of the lateral rectus muscle by branches of the oculomotor nerve leads to paradoxical co-contraction of horizontal recti. While classically unilateral, DRS may be bilateral in 10% to 20% of cases and is more commonly observed in females, with a predilection for the left eye. The etiology is linked to developmental anomalies of the abducens nerve (cranial nerve VI) or its nucleus, resulting in absent or hypoplastic innervation and compensatory miswiring from the oculomotor nerve. This neurogenic origin is supported by magnetic resonance imaging (MRI) studies demonstrating absent abducens nerve and electromyography findings of simultaneous lateral and medial rectus contraction during attempted adduction. In some cases, DRS is associated with systemic anomalies such as Goldenhar syndrome, Klippel–Feil anomaly, or other congenital malformations, reinforcing the notion of a broader embryologic insult affecting cranial nerve development. Clinically, DRS is classified into three primary types according to the Huber classification (1974): Type I: Marked limitation or absence of abduction, with relatively normal adduction and globe retraction on adduction. Type II: Limitation or absence of adduction with relatively normal abduction. Type III: Limitation of both abduction and adduction, often with significant globe retraction . Patients may also exhibit upshoots or downshoots on adduction due to leash effects or mechanical factors within the extraocular muscle pulleys. Abnormal head posture is common as patients adopt compensatory face turns to maintain binocular single vision in primary gaze. The severity of motility restriction and retraction varies widely, influencing functional and cosmetic concerns. Epidemiologically, DRS accounts for a small fraction of strabismus cases worldwide but carries substantial clinical importance due to its distinct presentation, surgical challenges, and potential associations with systemic disorders. Population-based studies indicate prevalence rates ranging from 0.1 to 0.7 per 1000 live births, though true incidence may be underestimated due to underdiagnosis in mild cases. Awareness among pediatricians, ophthalmologists, and orthoptists is critical for early recognition and evaluation. From a diagnostic standpoint, DRS is primarily a clinical diagnosis supported by a detailed ocular motility examination. Key signs include narrowing of the palpebral fissure on adduction, globe retraction, and variable upshoots or downshoots. Forced duction testing may reveal mechanical restrictions, but the hallmark finding is paradoxical co-contraction of horizontal recti, confirmed by electromyography. Imaging with high-resolution orbital MRI or diffusion tensor imaging can delineate the absence of the abducens nerve, providing objective confirmation and aiding in surgical planning. Assessment should also include evaluation for associated systemic anomalies, as up to 30% of patients may have other congenital malformations. Management of DRS is individualized and guided by the severity of motility limitation, abnormal head posture, and patient symptoms. Mild cases with good primary gaze alignment may require only observation and periodic follow-up. Surgical intervention is indicated for significant misalignment in primary gaze, large abnormal head posture, or cosmetically disturbing globe retraction and upshoots/downshoots. Procedures may include recession of the medial rectus, lateral rectus, or a combination, and vertical rectus transpositions in select cases. The surgical approach is often more complex than other forms of strabismus due to the paradoxical innervation and risk of exacerbating retraction. Overcorrection, induced vertical deviations, and persistent limitation are recognized challenges. DRS is nonprogressive, but long-term follow-up is essential to monitor ocular alignment, binocular function, and amblyopia risk, particularly in children. Amblyopia occurs in up to 10% of cases, necessitating prompt detection and treatment. Orthoptic therapy supports maintaining binocular vision and managing mild head postures, although it does not correct the underlying innervational anomaly. Recent advances in understanding DRS pathogenesis have emerged from genetic and neuroimaging studies. Mutations in genes such as CHN1 (encoding alpha2-chimaerin) have been identified in familial cases, implicating axon guidance defects in cranial nerve development. These findings place DRS within the broader category of CCDDs, alongside Möbius syndrome and congenital fibrosis of the extraocular muscles. This reclassification has shifted the focus from purely mechanical explanations to neurodevelopmental mechanisms, fostering novel research avenues. The psychosocial impact of DRS should not be underestimated. Visible eye movement anomalies and abnormal head posture can affect self-esteem, social interactions, and quality of life, particularly in adolescents. Counseling, patient education, and appropriate referral for psychological support may be beneficial in selected cases. In pediatric patients, parental reassurance and guidance are critical to alleviate anxiety and ensure adherence to follow-up schedules. Interprofessional collaboration is central to optimal DRS management. Pediatric ophthalmologists, orthoptists, neurologists, radiologists, and genetic counselors contribute to comprehensive evaluation and care. For example, neurologists may assess for associated cranial nerve or central nervous system anomalies, while genetic counselors provide insight into inheritance patterns and recurrence risks. Radiologists skilled in high-resolution orbital imaging are important in confirming diagnosis and guiding surgical strategy. Orthoptists assist with functional assessment, prism adaptation, and postoperative rehabilitation, enhancing overall outcomes. In conclusion, DRS represents a distinct, nonprogressive congenital ocular motility disorder with complex neurogenic and mechanical features. Advances in neuroimaging and genetics have enriched our understanding of its pathophysiology, while surgical and nonsurgical management strategies continue to evolve. Early recognition, thorough evaluation for systemic associations, individualized treatment planning, and long-term multidisciplinary follow-up are key pillars in optimizing patient functional and cosmetic outcomes. This educational activity equips learners with an evidence-based, clinically relevant framework for diagnosing and managing DRS, integrating current guidelines, expert consensus, and interprofessional care principles to improve patient-centered outcomes.

To report the clinical presentation and surgical outcomes of patients with Duane syndrome with primary position hypertropia, with or without coexisting horizontal deviation. We retrospectively reviewed records of patients diagnosed with Duane syndrome with vertical and associated horizontal deviations from January 2008 to July 2017. We collected data regarding patient age, gender, refractive error, presence or absence of amblyopia and history of strabismus surgery, as well as clinical subtype of Duane syndrome, abnormal head posture, measurement of horizontal and vertical deviation, and outcomes of strabismus surgery. Success was defined as post-operative primary position hypertropia <4 prism diopters (PD) and horizontal deviation <10 PD. During this period, a total of 590 patients with Duane syndrome were seen. Of these, 18 patients (10 males and 8 females) met the study criteria, giving a prevalence of 3%. Median age was 21 years. Seventy-eight percent cases had type III Duane syndrome. Ten patients underwent surgical correction, of which four patients had to undergo a second procedure after a median of 19 months. Sixty-seven percent of the patients had associated primary position exotropia with median deviation of 30 PD. Seventeen percent of patients had only primary position hypertropia with median 10 PD. All patients had overshoots. Primary position horizontal deviation improved from 25 PD to orthotropia, and vertical deviation improved from 10 PD to orthotropia. Lateral rectus recession with Y split was the most frequent procedure performed, and we saw a median reduction of 10 PD hypertropia with this procedure. Median follow-up period was 13 months. Success was achieved in 60% of the patients who underwent surgery. Given the small sample size, it was difficult to compare the efficacy of different procedures. Current study suggests that primary position vertical deviation might exist in 3% of patients with Duane syndrome. All patients had associated overshoots, which were predominantly of a mixed mechanism. Forty percent of the patients needed re-surgery. Well-designed, prospective possibly multicentric studies are necessary to understand the mechanism of overshoot, and consequently the primary position hypertropia to plan accurate management for these patients.