Review of the major findings about Duane retraction syndrome (DRS) leading to an updated form of classification

Relationship between retraction and refraction values in patients with Duane's retraction syndrome

PURPOSE

To evaluate refractive findings in patients with unilateral Duane's retraction syndrome (DRS).

METHODS

This retrospective study included 40 patients followed for unilateral DRS. Detailed ophthalmological examinations of the patients were performed. The spherical and cylindrical refractive error, spherical equivalent, and type of refractive error in the eyes with DRS and the fellow eyes were determined. The patients were divided into three subgroups according to their type of DRS. The refractive properties of the eyes with DRS were examined in subgroup analyses. Eye movement limitation was graded between +1 and +4 and compared according to the refractive error type.

RESULTS

The mean age of the patients was 16.8±12.6 (range, 1-60) years. Of the eyes with DRS, 11 (27.5%) were emmetropic, four (10%) were hyperopic, two (5%) were myopic, 11 (27.5%) were myopic astigmatic, and 12 (30.0%) were hyperopic astigmatic. There was no statistically significant difference between the eyes with DRS and fellow eyes in relation to the spherical or cylindrical refractive errors or spherical equivalent (P>0.05 for all). The refraction values for the patients with type 1, type 2 and type 3 DRS were similar between groups (P>0.05). No statistically significant difference was detected in the degree of eye movement limitation according to refractive status (P>0.05).

CONCLUSION

In patients with unilateral DRS, there was no significant difference between the affected eyes and the fellow eyes in terms of refractive error values or types. Refractive status did not significantly differ according to the degree of eye movement limitation. Therefore, although extraocular muscles are affected by DRS, there may not be any significant refractive changes.

MRI evaluation of cranial nerve abnormalities and extraocular muscle fibrosis in duane retraction syndrome and congenital extraocular muscle fibrosis

PURPOSE

To investigate the alterations in extraocular muscles (EOMs) by magnetic resonance imaging (MRI) among patients diagnosed with Duane retraction yndrome (DRS) and congenital fibrosis of the extraocular muscles (CFEOM), who present with various cranial nerve anomalies in an attempt to enhance the clinical diagnostic process.

METHODS

A case-control study was conducted to evaluate 27 patients with DRS and 14 patients with CFEOM. All patients underwent MRI scans of the brainstem and orbital examination. Neurodevelopmental assessments were conducted through MRI, and maximum cross-sectional area and volumes of EOMs were obtained. Three types of models were constructed using machine learning decision tree algorithms based on EOMs to predict disease diagnosis, cranial nerve abnormalities, and clinical subtypes.

RESULTS

Patients with bilateral CN VI abnormalities had smaller volumes of LR, MR, and IR muscles compared to those with unilateral involvement (P < 0.05). Similarly, patients with CFEOM and unilateral third cranial nerve abnormalities had a smaller maximum cross-section of the affected eye's SR compared to the contralateral eye (P < 0.05). In patients with both CN III and CN VI abnormalities, the volume of SR was smaller than in patients with CN III abnormalities alone (P < 0.05). The prediction model using EOMs volume showed a diagnostic precision of 82.5% for clinical cases and 60.1% for predicting cranial nerve abnormalities. Nonetheless, the precision for identifying clinical subtypes was relatively modest, at only 41.7%.

CONCLUSION

The distinctive volumetric alterations in EOMs among individuals exhibiting distinct cranial nerve anomalies associated with DRS or CFEOM provide valuable diagnostic insights into to Congenital Cranial Neurodevelopmental Disorders (CCDDs). MRI analysis of EOMs should thus be regarded as a crucial diagnostic modality.

Refractive features and amblyopia in Duane's Retraction Syndrome: A review of the 582 patients

PURPOSE

To report the visual and refractive characteristics and the prevalence of amblyopia in patients with different types of Duane's Retraction Syndrome (DRS).

METHOD

This retrospective study was performed on hospital records of 582 DRS patients at Farabi Hospital, Iran, from 2012 to March 2022.

RESULTS

The mean age of patients was 19.4 ± 11.9 (range, 3-70) years [335 (57.6 %) females and 247 (42.4 %) males (P < .001)]. DRS type I, II, III, and IV were presented in 347 (59.6 %), 148 (25.4 %), 82 (14.1 %), and 5 (0.9 %) patients, respectively. There were 530 (91.1 %) patients with unilateral and 52 (8.9 %) with bilateral involvement. In the unilateral patients, the DRS eyes' corrected distance visual acuity (CDVA) and astigmatism were significantly worse than the Non-DRS Eyes (P < .001). The mean amount of all refractive and visual parameters in bilateral patients' right or left eyes was significantly lower than in unilateral patients' non-DRS eyes (all P < .05). Anisometropia was observed in 75(12.9 %) of the patients. Amblyopia was observed in 18.5 % (98 patients) and 36.5 % (19 patients) of unilateral and bilateral DRS patients, respectively (P < .001). In unilateral patients, amblyopia was found in 57 (16.4 %) patients with Type I, 22 (14.9 %) patients with Type II, 16 (19.5 %) patients with Type III, and 3 (60 %) patients with Type IV. Forty-four (37.6 %) of patients with amblyopia had anisometropia.

CONCLUSION

This large-scale study indicates that DRS types differ in terms of refractive error, visual acuity, and the prevalence of amblyopia and anisometropia. Clinicians should be aware of the clinical features associated with different types of DRS.

Special clinical features with a novel mutation site of CHN1 gene in a Chinese family with Duane retraction syndrome

PURPOSE

This study is to describe the special clinical and genotypic features of a Chinese family with variant types of Duane retraction syndrome and to present our experience on managing these cases.

METHODS

Four individuals from one family were reviewed by ophthalmologic examinations, in which two affected and two unaffected individuals were revealed. MRI scans were performed on the two patients. Relevant gene mutations were screened by the next-generation sequencing technology and confirmed by Sanger sequencing technology.

RESULTS

The six-year-old proband presented with special clinical features of severe horizontal gaze dysfunction, exotropia and mild scoliosis. His mother showed significantly limited binocular abductions, with retraction of eyeballs in adduction. From MRI scans, abducens nerves were not observed in both patients and the oculomotor nerve was slightly thin in the proband. The proband and his mother shared the same CHN1 gene mutation site (c. 62A>G; p.Y21C). Strabismus surgery was performed on the proband to correct the primary gaze exotropia.(NM_001822: exon3 or NM_001025201: exon4: c. 62A>G; p.Y21C).

CONCLUSIONS

A novel CHN1 gene mutation was revealed from a Chinese family with Duane retraction syndrome. Remarkably, the proband and his mother presented different clinical features of ocular motility disorder. Strabismus correction surgery and amblyopia training helped to improve the appearance and visual function of the proband.

Magnetic Resonance Imaging Findings in Patients With Duane Retraction Syndrome

BACKGROUND

Duane retraction syndrome (DRS) is known to relate to the absence of the abducens nucleus, with abnormal innervation of the lateral rectus (LR) muscle by branchesof the oculomotor nerve (CN III). The purposes of this study were to investigate the morphological characteristics of the oculomotor nerve (CN III), the abducens nerve (CN VI), and the extraocular muscles in patients with clinically diagnosed Duane retraction syndrome (DRS) using MRI. In addition, we assessed the association between ocular motility, horizontal rectus muscle volumes, and CN III/VI in patients with Duane retraction syndrome (DRS).

METHODS

The study comprised 20 orthotropic control subjects (40 eyes) and 42 patients with Duane syndrome (48 eyes), including 20 patients with DRS Type I (24 eyes), 5 patients with DRS Type II (6 eyes), and 17 patients with DRS Type III (18 eyes). Three-dimensional (3D) T1/2 images of the brainstem and orbit were obtained to visualize the cranial nerves, especially the abducens (VI) and oculomotor (III) nerves, as well as extraocular muscles.

RESULTS

Based on the clinical classification, among 42 patients, MRI showed that the abducens nerves (CN VI) on the affected side were absent in 24 of 24 eyes (100%; 20 patients) with Type I DRS and in 16 of 18 eyes (88%; 16 patients) with Type III DRS. However, CN VI was observed in 6 of 6 eyes (100%; 5 patients) with Type II DRS and in 2 of 18 eyes (11%) with Type III DRS. CN III was observed in all patients. The oculomotor nerves on the affected side were thicker than those on the nonaffected contralateral side in DRS Type I ( P < 0.05) and Type III ( P < 0.05), but not in DRS Type II. Smaller LR and larger MR volumes were shown in the affected eye than that in the nonaffected eye in DRS Types I and III. Based on the presence or absence of CN VI, there was a tendency for thicker oculomotor nerves in the affected eye than in the nonaffected eye in the absence groups ( P < 0.05). However, no significant difference was found in the present group. In the CN VI absence groups, similar results were found in the affected eyes than in the nonaffected eyes as in DRS Types I and III. In addition, the presence of CN VI was correlated with better abduction ( P = 0.008). The LR and MR volumes have positive correlations with the oculomotor nerve diameter in the affected eye. However, there was no correlation between the range of adduction/abduction and the LR/MR ratio in patients with or without an abducens nerve.

CONCLUSIONS

Different types of DRS have different characteristic appearances of CN VI and CN III on MRI. Horizontal rectus muscles have morphological changes to adapt to dysinnervation of CN VI and aberrant innervation of CN III. Thus, these neuroimaging findings may provide a new diagnostic criterion for the classification of DRS, improving the comprehension of the physiopathogenics of this disease.

Interocular Symmetry in Retinal Nerve Fiber Layer Thickness in Children: The Hong Kong Children Eye Study

INTRODUCTION

The aim of this work is to determine the interocular differences in peripapillary retinal nerve fiber layer (p-RNFL) thickness and its associations among school children in Hong Kong.

METHODS

We conducted a population-based study including 4034 children aged 6-8 years from the Hong Kong Children Eye Study (HKCES). All participants received comprehensive ocular examinations where p-RNFL thickness was measured using spectral-domain optical coherence tomography (SD-OCT). The degree of symmetry between both eyes was analyzed and represented by intraclass correlation coefficient (ICC) values. Multivariable linear regression analysis was used to investigate the associations between ocular and systemic factors with p-RNFL thickness difference.

RESULTS

The study included 4034 children with a mean age of 7.61 ± 0.98 years. The mean global p-RNFL thickness was 106.60 ± 9.41 μm in right eyes and 105.99 ± 9.30 μm in left eyes. The ICC for global p-RNFL difference was 0.866 (95% CI 0.858-0.873, p < 0.001). The symmetry displayed the largest values in nasal inferior quadrant with the ICC value of 0.736 (95% CI 0.721-0.749); and the smallest degree of symmetry was found to be in the superior temporal quadrant with the ICC value of 0.567 (95% CI 0.546-0.588). Axial length (AL) difference was found to have more pronounced correlation to interocular symmetry in p-RNFL thickness with the coefficient of 0.514 (p < 0.001).

CONCLUSIONS

Normal variation in interocular symmetry exists in children. Our results can contribute to the establishment of a standard reference for interocular differences in OCT parameters in children. The interocular differences in AL should be considered in the interpretation of RNFL symmetry, in terms of identifying children at risk of developing glaucoma or other ocular disorders.

Bilateral Lateral Rectus Recession in Duane Retraction Syndrome Type II: A Case Report

A two year presented to the clinic with abnormal head posture and right-sided face turn since birth. On examination, he showed a large right face turn of 40° while concentrating on a near target. His ocular motility assessment showed a -4 limitation of adduction in the left eye with 40 prism diopters (PD) exotropia and grade 1 globe retraction of the left eye. He was diagnosed with type II Duane retraction syndrome (DRS) in the left eye and planned for lateral rectus recession of both eyes. Postoperatively, the patient was orthotropic at distance and near in primary gaze with resolved face turn and improvement of limitation of adduction to -2, but some limitation of abduction -1 in the left eye was observed. Herein, we discuss the clinical features, etiologies, tailored evaluation, and management for type II DRS patient.

[Improvement of surgical treatment of Duane syndrome in children]

PURPOSE

To analyze the use of bifurcation of the lateral rectus muscle (LRM) in the surgical treatment of Duane syndrome (DS) in children.

MATERIAL AND METHODS

The analysis of surgical treatment involved 12 children with paralytic strabismus at the age of 8 to 17. The following research methods were conducted for all patients: the study of eye motility in different directions of gaze, the study of eyes position and the degree of deviation in different positions of gaze, the Bielschowsky test, the Park's three-step test, determination of the nature of torticollis, the forcing test - intraoperative forceps test, multislice computed tomography (MSCT) of the head and orbit, ultrasonography of the oculomotor muscles. All study children underwent bifurcation (Y-cleavage procedure) of LRM with recession in exo-DS in 17% of cases, without recession in eso-DS - 83% of cases, respectively.

RESULTS

In all operated patients with Duane syndrome, the direction of LRM was compensated (downshoot and upshoot were eliminated). In a direct gaze, the correct position was achieved in 10 (83%) cases, in 2 (17%) the residual angle of up to 10 PD remained, and torticollis was eliminated in 9 (75%) patients.

CONCLUSION

The method of LRM bifurcation - the procedure of dividing the muscle into two portions and changing its primary localization, accompanied by abnormalities (presence of deviation, retraction, anomalous vertical movements, limited ocular motility, etc.), - helps compensate for them, and provides cosmetic as well as functional improvement.

Ocular Asymmetry in Electrooculographic Responses

Between the cornea and the posterior pole of the eye, there is a transepithelial potential capable of being registered through an electrooculogram (EOG). It is questionable whether electrooculographic responses are similar in both eyes despite ocular dominance in human beings. We studied the effect of different electrooculographic stimulation parameters, in terms of directionality, linear and angular velocity, contrast, and state of adaptation to light/dark, that may induce possible interocular differences in visual function. The study was carried out with electroencephalography-type surface electrodes placed in the medial, lateral, superior, and inferior positions of both human eyes to record the eye movements. We found a greater amplitude of the EOG response in the left eye than to the right eye for light bars moving from right to left (p < 0.01; t-test). The EOG response amplitude was similar in both eyes for light bars moving in vertical directions, but greater than horizontal or rotational stimuli. We conclude that vertical stimuli should be used for EOG functional evaluation of eye movements, since horizontal stimuli generate significant interocular differences.

Diplopia in Cases With Type 1 Duane Retraction Syndrome

Objective In this study, we aimed to investigate the prevalence of diplopia in cases with type 1 Duane retraction syndrome (DRS). Materials and methods This study was a retrospective review of cases involving patients presenting diagnosed with DRS over a period of 24 years. Among these cases, 28 had type 1 DRS and fulfilled the inclusion criteria. The cases were evaluated in terms of age, gender, affected eye, concomitant ocular motility disorders, presence of amblyopia, manifest shift, abnormal head position (AHP), fusion, and stereopsis. Results Sixteen of the patients (57.1%) in the study were female, and 12 (42.8%) were male; the mean age of the patients was 18.9 years (range: 7-67 years). The right eye was affected in six of the cases (21.4%), and the left eye in 22 (78.6%) of the cases. On examination, diplopia was not observed in 21 (75%) cases, but it was detected in seven (25%). AHP was present in five of the seven cases with diplopia and not present in two, and all seven of the diplopic cases had fusion, while three had stereopsis. The level of stereopsis in all diplopic cases was 400 sn/ark. When the clinical findings of patients with diplopia and those without diplopia were compared, a statistically significant difference was observed only in terms of AHP. Conclusions Although diplopia is not one of the clinical features of DRS, it must be noted that in cases with type 1 DRS, diplopia may occur in directions in which the movement of the eyeball is limited. In the presence of this finding, which might mimic sixth nerve palsy, patient history must be diligently taken, other clinical findings of DRS must be thoroughly examined, and an MRI should be performed when necessary for an easier diagnosis.

A rare association of type 2 Duanes retraction syndrome with arthrogryposis multiplex congenita

A 10-year-old boy presented with complaints of abnormal eye movements and face turn since early There was a limitation of adduction in LE with narrowing of palpebral fissure and downshoot characteristic of type 2 Duane Syndrome. He was a known case of Arthrogryposis multiplex congenita (AMC) and had undergone multiple orthopedic surgeries. The literature on Duane Retraction Syndrome (DRS) in AMC is limited. Here, we report in brief the association of DRS type 2 in AMC.

Contralateral lateral rectus muscle recession in a patient with unilateral exotropic Duane retraction syndrome type II: A case report

A fixation preference for the affected eye is uncommon in patients with unilateral Duane retraction syndrome (DRS), and surgery on the fellow eye is rarely advocated. We are presenting a case report of a 9-year-old boy with unilateral DRS type II in the left eye who received lateral rectus muscle recession in his right amblyopic eye. The patient was orthophoric and his face turn was gone 6 months postoperatively. Surgery on the fellow amblyopic eye is a good choice for unilateral DRS where the affected eye dominants the fixation, and the satisfactory outcome suggests that alignment in the primary position can correct the face turn effectively despite the muscle duction deficit in the affected eye and further extend the binocular single visual field.

Surgical Outcomes of Exotropic Duane Retraction Syndrome From a Tertiary Eye Care Center

PURPOSE

To report surgical outcomes of patients with exotropic Duane retraction syndrome.

METHODS

A retrospective review of the medical records from patients with exotropic Duane retraction syndrome who underwent strabismus surgery and had at least 2 months of postoperative follow-up was conducted. Surgical success was defined as a postoperative horizontal deviation within 8 prism diopters (PD), abnormal head posture (AHP) less than 5 degrees, and a two-step decrease in overshoots.

RESULTS

Seventy-three patients with exotropic Duane retraction syndrome (38, 52% male, mean age 14 ± 7.9 years) met the study criteria. Unilateral type 3 Duane retraction syndrome was seen in 56 (77%) patients and type 1 in 14 (19%) patients. The mean follow-up period was 22 weeks (range: 8 to 209 weeks). Unilateral and bilateral lateral rectus recession were performed in 48 (65%) and 25 (34%) patients, respectively. In addition to recession, a lateral rectus Y-splitting was performed in 42 (56%) patients. Five patients underwent differential medial rectus and (larger) lateral rectus recession to alleviate severe globe retraction. The mean primary position reduced from 23 PD (CI: 19.6 to 26 PD) preoperatively to 9 PD (CI: 7.02 to 11.02 PD) postoperatively (P < .0001). Postoperatively 50% of patients were orthotropic in the primary position. Surgical success for primary position deviation, AHP, and overshoots were achieved in 74%, 81%, and 71% of patients, respectively.

CONCLUSIONS

In the current study, type 3 Duane retraction syndrome was the most common subtype necessitating surgery for exotropic Duane retraction syndrome. Good surgical outcomes were obtained for various indications. Unilateral or bilateral lateral rectus recession was successful in improving motor alignment and AHP. The addition of lateral rectus Y-splitting corrected overshoots greater than grade 2 in most patients with exotropic Duane retraction syndrome. [J Pediatr Ophthalmol Strabismus. 2021;58(1):9-16.].

Hummelsheim procedure combined with medial rectus recession in complete sixth nerve palsy and esotropic Duane Retraction Syndrome

PURPOSE

To evaluate the effect of half tendon vertical rectus muscle transposition (HVRT) combined with medial rectus muscle recession (MRrec) in complete sixth nerve palsy (CSNP) and esotropic Duane Retraction Syndrome (eDRS).

METHODS

A retrospective study of patients with unilateral CSNP or eDRS who underwent HVRT combined with medial rectus recession over the course of 18 years. The patients with previous strabismus surgery and follow up less than 3 months were excluded. Overcorrection was defined as any amount of exotropia, and undercorrection was defined as residual esotropia of ⩾10 prism diopter (PD).

RESULTS

A total of 39 patients were enrolled including 22 CSNP and 17 eDRS patients. Esotropia improved from 45.8 ± 22 and 22.5 ± 6.4 PD to 0.8 ± 2.5 and 0.3 ± 1 PD in CSNP group and eDRS group respectively. The angle of face turn improved from 34.3 ± 8.4° and 26.5 ± 9° to 0.6 ± 2.4° and 0.8 ± 1.6° in the CSNP group and eDRS group respectively. Abduction limitation improved from -4.5 ± 0.5 and -4 ± 0 units to -2.9 ± 0.5 and -2.7 ± 0.5 units in CSNP group and eDRS group respectively. No patient developed a new vertical deviation. An overcorrection occurred in one patient of the eDRS group who improved after botulinum toxin injection in the ipsilateral lateral rectus muscle. Undercorrection was seen in two patients.

CONCLUSION

HVRT combined with MRrec is an effective procedure to improve esotropia, face turn, and abduction limitation in CSNP and eDRS.

Ocular structural changes in patients with Duane retraction syndrome: Does a correlation exist?

Purpose:

The purpose of this study was to investigate the structural changes (axial length, central macular thickness (CMT), subfoveal choroidal thickness, and keratometry) in subjects with unilateral Duane retraction syndrome (DRS) as compared with the normal fellow eye.

Methods:

In this prospective study, we included 34 subjects with unilateral DRS from January 2016 to December 2016 seen at our institute. Data was collected for axial length, keratometry using partial coherence interferometry, CMT, subfoveal choroidal thickness using the enhanced depth imaging-optical coherence tomography (EDI-OCT). All these measurements were compared between the affected and fellow eye.

Results:

During this period, we included 34 subjects with unilateral DRS (22 Type I, 1 Type II, and 11 Type III). The mean age (±SD) of subjects was 14 ± 8 years (range: 5–28 years). There were 15 males and 19 females. Eyes with DRS were significantly shorter (median axial length 22.4 mm, interquartile range (IQR): 21.56 - 23.17) as compared to fellow eye (median axial length 22.7 mm, IQR: 22.35-23.55), P = 0.04. Choroidal thickness, CMT, and average keratometry were similar in DRS and fellow eyes (P = 0.39, 0.06, and 0.11, respectively). A significant difference in axial length was found only between Type I and Type III DRS (P = 0.03).

Conclusion:

This study suggests that in subjects with DRS, the affected eye has shorter median axial length when compared with the fellow eye. Prevalence of refractive error in eye with DRS was higher compared to fellow eye. But, there was no difference in magnitude of refractive error found between eye with DRS and normal fellow eye.

Non-classical 1p36 deletion in a patient with Duane retraction syndrome: case report and literature review

Background

Monosomy of 1p36 is considered the most common terminal microdeletion syndrome. It is characterized by intellectual disability, growth retardation, seizures, congenital anomalies, and distinctive facial features that are absent when the deletion is proximal, beyond the 1p36.32 region. In patients with proximal deletions, little is known about the associated phenotype, since only a few cases have been reported in the literature. Ocular manifestations in patients with classical 1p36 monosomy are frequent and include strabismus, myopia, hypermetropia, and nystagmus. However, as of today only one patient with 1p36 deletion and Duane retraction syndrome (DRS) has been reported.

Case presentation

We describe a patient with intellectual disability, facial dysmorphism, and bilateral Duane retraction syndrome (DRS) type 1. Array CGH showed a 7.2 Mb de novo deletion from 1p36.31 to 1p36.21.

Discussion

Our patient displayed DRS, which is not part of the classical phenotype and is not a common clinical feature in 1p36 deletion syndrome; we hypothesized that this could be associated with the overlapping deletion between the distal and proximal 1p36 regions. DRS is one of the Congenital Cranial Dysinnervation Disorders, and a genetic basis for the syndrome has been extensively reported. The HES3 gene is located at 1p36.31 and could be associated with oculomotor alterations, including DRS, since this gene is involved in the development of the 3rd cranial nerve and the 6th cranial nerve’s nucleus. We propose that oculomotor anomalies, including DRS, could be related to proximal 1p36 deletion, warranting a detailed ophthalmologic evaluation of these patients.

Superior Rectus Transposition With Medial Rectus Recession Versus Medial Rectus Recession in Esotropic Duane Retraction Syndrome

PURPOSE

To compare the results of augmented superior rectus transposition (with or without medial rectus recession) with simple medial rectus recession in the treatment of patients with esotropic Duane retraction syndrome.

METHODS

This was a prospective, randomized, and interventional comparative study of 20 patients with esotropic type 1 Duane retraction syndrome. Patients were randomly divided into two groups. In the first group (superior rectus transposition group), superior rectus transposition with or without medial rectus recession was performed. In the second group (non-superior rectus transposition group), unilateral medial rectus recession was performed.

RESULTS

Each group included 10 patients. Esotropia improved from 20.4 prism diopters (PD) preoperatively to 0.6 PD postoperatively in the superior rectus transposition group and from 22.5 PD preoperatively to 0.9 PD postoperatively in the non-superior rectus transposition group. Face turn improved from 11.5° preoperatively to 0.5° postoperatively in the superior rectus transposition group and from 12° preoperatively to 1.5° postoperatively in the non-superior rectus transposition group. Abduction improved in the superior rectus transposition group from -3.9 preoperatively to -3.1 postoperatively and from -3.9 preoperatively to -3.6 postoperatively in the non-superior rectus transposition group. Vertical deviation developed in two cases in the superior rectus transposition group.

CONCLUSIONS

Both superior rectus transposition and medial rectus recession are effective in the elimination of esotropia and face turn in patients with esotropic Duane retraction syndrome. Superior rectus transposition is more effective in improving abduction, but it can be complicated by vertical deviation. [J Pediatr Ophthalmol Strabismus. 2020;57(5):309-318.].

Unilateral medial rectus muscle recession combined lateral rectus muscle marginal myotomy for the treatment of Duane's retraction syndrome: A promising surgical procedure

Background:

Duane's retraction syndrome is a congenital eye movement anomaly with narrowing of the palpebral fissure and globe retraction on attempted adduction. There are several surgical approaches to treat the narrowing of the palpebral fissure. The purpose of the present study was to evaluate the efficacy of unilateral medial rectus recession (MRR) muscle combined lateral rectus (LR) muscle marginal myotomy (MM) with unilateral MRR alone in the management of narrowing of the palpebral fissure of patients with Type 1 Duane's retraction syndrome (DRS).

Materials and Methods:

Twenty-eight patients with unilateral DRS Type 1 were randomly divided into two groups (14 eyes of 14 patients in each group). Age ≥5 years with DRS Type 1 with <20 prism diopters in primary position who were candidates for surgery were consecutively enrolled in this randomized controlled trial. Patients were divided into treatment groups to receive unilateral MR recession with simultaneous MM group or with unilateral MR recession alone. The amount of deviation in primary position, abnormal head position, palpebral fissure width (PFW), and up/down shoot was evaluated before and 3 months after the surgery. This study was registered at the Iranian Registry of Clinical Trials under the registration code IRCT20131229015975N3.

Results:

PFW increased within MRR/MM group at the end of the study (8.86 ± 1.51) compared with the baseline (7.79 ± 1.48) (P < 0.001). In contrast, in the MRR/MM group, PFW did not increase statistically significantly within the MRR group at the end of the study (8.14 ± 1.35) compared with the baseline (8.07 ± 1.38) (P = 0.67). Mean ± standard deviation of PFW (mm) in MRR/MM group after surgery (8.86 ± 1.51) was statistically significantly higher than that in the MRR group (8.14 ± 1.35), (P = 0.002).

Conclusion:

The results of our study demonstrate PFW significantly increased after unilateral MRR muscle combined LR muscle MM.

Facial Asymmetry in Unilateral Duane Retraction Syndrome

SIGNIFICANCE

The overall objective of this study was to evaluate facial asymmetry in patients with unilateral Duane retraction syndrome (DRS). The results showed a high frequency of facial asymmetry parameters of the opposite side of head turn in unilateral DRS patients.

PURPOSE

The purposes of this study were to evaluate the characteristics of facial asymmetry in unilateral exotropic and esotropic DRS and to compare the findings with orthotropic subjects.

METHODS

This cross-sectional comparative case series study was performed in 44 consecutive patients with head turn caused by DRS and 44 orthotropic subjects from 2016 to 2019. Four pictures were taken from the patients' faces. The first and second pictures were taken when patients had head turn and when the head was completely straight for calculating the facial angle and relative facial size, respectively. The third and fourth pictures were taken when the head was positioned downward (to compare the size of the cheek) and upward (to evaluate nose asymmetry).

RESULTS

The mean ± SD age of DRS patients and orthotropic subjects was 16.23 ± 9.92 and 20.68 ± 11.82 years, respectively. The frequency of facial asymmetry and all facial parameters (cheek compression, nasal tip and columella deviation, and compression of one of the nostrils) was significantly higher in DRS patients compared with orthotropic subjects (P < .001). In DRS patients with facial asymmetry, columella and nasal tip deviation (P = .006) and cheek and face compression (P = .03) were significantly more prevalent in the opposite direction of head turn. In the DRS group, the mean ± SD age of the patients with and without facial asymmetry was 17.37 ± 9.76 and 7.40 ± 6.54 years, respectively (P = .02).

CONCLUSIONS

The frequency of facial asymmetry and all facial parameters was significantly higher in DRS patients compared with orthotropic subjects. In unilateral DRS patients, the face was more commonly affected on the opposite side of head turn.

Ocular Motor Dysfunction Due to Brainstem Disorders

BACKGROUND

The brainstem contains numerous structures including afferent and efferent fibers that are involved in generation and control of eye movements.

EVIDENCE ACQUISITION

These structures give rise to distinct patterns of abnormal eye movements when damaged. Defining these ocular motor abnormalities allows a topographic diagnosis of a lesion within the brainstem.

RESULTS

Although diverse patterns of impaired eye movements may be observed in lesions of the brainstem, medullary lesions primarily cause various patterns of nystagmus and impaired vestibular eye movements without obvious ophthalmoplegia. By contrast, pontine ophthalmoplegia is characterized by abnormal eye movements in the horizontal plane, while midbrain lesions typically show vertical ophthalmoplegia in addition to pupillary and eyelid abnormalities.

CONCLUSIONS

Recognition of the patterns and characteristics of abnormal eye movements observed in brainstem lesions is important in understanding the roles of each neural structure and circuit in ocular motor control as well as in localizing the offending lesion.

Utility of Magnetic Resonance Imaging (MRI) in Children With Strabismus

PURPOSE

Magnetic resonance imaging (MRI) of the brain can provide valuable information about structural abnormalities in strabismus. The aim of this study was to evaluate the utility of MRI in this regard and to identify risk factors for abnormal MRI results in children with strabismus.

METHODS

A retrospective analysis of children <18 years of age presenting with strabismus, who underwent brain MRI at Pusan National University Hospital (Busan, Korea) between January 2012 and March 2017, was performed. Clinical characteristics, MRI results, and ophthalmologic findings were reviewed. Findings were classified as normal or abnormal according to MRI results. Additionally, patients were divided according to age to compare characteristics of infantile and childhood strabismus.

RESULTS

A total of 90 patients (47 [52.2%] male, 43 [47.8%] female; mean age, 2.19 ± 0.53 years) were enrolled. Of those, 64 (71.1%) presented with normal and 26 (28.9%) with abnormal MRI results. The age at presentation was lower and abnormal findings on fundus examination were more common in the abnormal MRI group (P = .002 and P = .008, respectively). Among the patients, 46 (51.1%) had infantile strabismus and 44 (48.9%) had childhood strabismus. Global developmental delays, speech delays, and MRI abnormalities were more common in patients with infantile than in those with childhood strabismus. Ptosis and headaches were more common in patients with childhood strabismus (P = .025, P = .025, respectively).

CONCLUSION

Brain MRI was helpful for accurate diagnosis and treatment of strabismus in younger children, those with abnormal findings on fundus examination, and infants with developmental, especially speech, delays.

Binocular Function in Subjects with Orthotropic Duane Retraction Syndrome

Introduction and Purpose: The aim of this study is to evaluate binocular vision parameters such as near point of accommodation (NPA), near point of convergence (NPC), fusional vergence ranges in subjects with orthotropic Duane retraction syndrome (DRS) and to compare with normal age-matched controls Patients and Methods: A total of 24 subjects (14 Type 1, 2 Type 2, 8 Type 3 DRS) who were diagnosed to have DRS and 15 normals were included in the study. The following binocular vision parameters were assessed in all subjects: amount of the deviation (for near and distance in all gazes), NPC, NPA, positive and negative fusional vergence (PFV and NFV) reserve and stereopsis. Results: Accommodative amplitude was normal in subject with DRS (median (95% confidence interval (CI):15D (11.9-18.1)) compared to age-matched controls. However, NPC was significantly receded (median [95% CI]:17 cm [14.4-19.6]). PFV reserve and NFV reserve were reduced in subjects with DRS. Subjects with Type 3 DRS have poor PFV reserve and NFV reserve for distance when compared to Type 1 DRS (p = 0.009 and 0.006 respectively). Stereopsis was poor in the subjects with DRS (p < 0.001). Conclusion: Subjects with DRS have good accommodation, but have poor convergence and fusional vergence. Stereopsis was noted to be poor as well.

Duane Retraction Syndrome: Clinical Features and a Case Group-Specific Surgical Approach

PURPOSE

To describe the clinical features of patients with Duane retraction syndrome (DRS) and evaluate the outcomes of surgical approaches based on the characteristics of each patient.

METHODS

The records of 38 Caucasian subjects with DRS were retrospectively reviewed. The patients were classified as type I, II, or III based on the Huber Classification. Ten patients underwent unilateral medial rectus (MR) recession due to abnormal head posture (AHP) and/or esotropia. Four patients underwent Y-splitting and recession of the lateral rectus (LR) with MR recession due to AHP and/or esotropia, upshoot, and globe retraction.

RESULTS

There was a preponderance of unilaterality, female gender, left eye, type I, orthotropia, upshoot, and low refractive error. All patients demonstrated globe retraction and fissure narrowing. AHP was only present in unilateral cases. Nine patients had amblyopia. More than half of the patients over 5 years of age had decreased stereopsis. MR recession decreased AHP to less than 8° in all patients. Y-splitting and recession of the LR eliminated upshoot in all four patients. One patient who underwent an 8-mm MR recession demonstrated -2 adduction limitation.

CONCLUSIONS

The DRS patients in our study demonstrated features that are consistent with previous reports in the literature. This study emphasizes the need to consider disease classification in the surgical management of DRS patients.

Anomalous Vertical Deviations in Attempted Abduction Occur in the Majority of Patients With Esotropic Duane Syndrome

PURPOSE

To describe a phenomenon, depression in attempted abduction, not previously recognized as a feature of Duane syndrome (DS).

DESIGN

Retrospective, observational case series.

METHODS

Setting: Institutional practice.

PATIENT POPULATION

Patients diagnosed with esotropic DS at Boston Children's Hospital from 2002 to 2015. Patients with clinical photographs documenting horizontal gaze were included. Patients with prior strabismus surgery were excluded.

OBSERVATION PROCEDURES

Patients were classified into 3 groups according to their vertical eye position in attempted abduction: midline group, depression group, and elevation group. Group assignment was performed by 3 independent ophthalmologists. Baseline characteristics, eye movement, and ocular deviation were compared among the 3 groups.

MAIN OUTCOME MEASURES

Horizontal and vertical deviation on attempted abduction in the DS eye.

RESULTS

Depression in attempted abduction was present in 74 of 113 unilateral patients (66%) and 18 of 42 gradable eyes (43%) of bilateral patients. Abduction limitation was significantly less severe in the midline group (median: -3.0) than in the depression group (median: -4.0) (P = .01). Vertical deviation in attempted abduction was more severe in the elevation group than in the depression group (P = .003).

CONCLUSIONS

Depression of the eye in attempted abduction has not been widely described, yet it is present in the majority of DS patients. It is more likely to occur with more severe abduction limitation. This phenomenon is likely another form of dysinnervation in DS, the result either of anomalous vertical rectus muscle activation or asymmetric lateral rectus muscle innervation during attempted abduction. Awareness of vertical deviation in attempted abduction may facilitate surgical planning in affected patients.

The Efficacy of Bilateral Lateral Rectus Recession According to Secondary Deviation Measurements in Unilateral Exotropic Duane Retraction Syndrome

PURPOSE

To evaluate the surgical results of asymmetric bilateral lateral rectus recession in exotropic Duane retraction syndrome with abnormal face turn toward the opposite side according to secondary deviation measurements.

METHODS

Retrospective chart review.

RESULTS

Seven cases of unilateral exotropic Duane retraction syndrome were reviewed. All cases had globe retraction on adduction and exotropia with limited adduction, five of which also had mild limitation of abduction. Four cases had upshoot/downshoot on adduction and all patients had face turn. Exotropia was measured in forced primary position. The average lateral rectus recession was 6.36 mm (range: 5.5 to 7.5 mm) in the affected eye and 7.36 mm (range: 6.5 to 8.5 mm) in the healthy eye. The mean follow-up period was 282 days. Mean exotropia in the forced primary position improved from 27.9 ± 5.7 prism diopters (PD) preoperatively to 7.9 ± 16.8 PD postoperatively (P = .025). Head position resolved completely in all but one case (P =.031). There were no significant changes in ductions.

CONCLUSIONS

The results suggest that asymmetric bilateral lateral rectus recession in exotropic Duane retraction syndrome with abnormal head turn posture successfully eliminates abnormal head turn posture and exotropia in most cases. [J Pediatr Ophthalmol Strabismus. 2018;55(1):47-52.].

CHN1 gene mutation analysis in patients with Duane retraction syndrome

PURPOSE

To investigate CHN1 (chimerin 1) gene mutations in patients with isolated nonsyndromic Duane syndrome and accompanying positive familial history, bilaterality, or various systemic disorders.

METHODS

Patients with Duane retraction syndrome (DRS) and a positive family history of congenital ocular motility disturbance or bilateral involvement or accompanying any congenital disorder(s) seen consecutively at a single center from 2013 to 2016 were enrolled. All subjects underwent full ophthalmologic examination, including refraction, best-corrected visual acuity, ocular alignment and motility, globe retraction, and biomicroscopic or fundus evaluation. DNA samples were investigated by direct sequencing of the coding regions of the CHN1 gene.

RESULTS

A total of 30 patients (15 males) were included (mean age, 11.8 ± 10.4 years; range, 2-45 years): 8 cases presented with bilateral DRS; 22, with unilateral DRS. Family history of ocular motility abnormality was positive in 16 patients. Eleven cases had an additional congenital disorder. In 2 patients, 2 different mutations were detected in the CHN1 gene: p.E313K (c.937G>A) and p.N224S (c.671A>G).

CONCLUSIONS

CHN1 mutations were identified in 2 bilateral cases and in 1 parent of 1 affected case. One mutation is novel and occurred with additional vertical gaze abnormalities. Additional genetic studies evaluating chimerin 1 (CHN1) and its role in the development of the ocular motor axis are needed to provide new data about these mutations and phenotypic variations.

Duane retraction syndrome: causes, effects and management strategies

Duane retraction syndrome (DRS) is a congenital eye movement anomaly characterized by variable horizontal duction deficits, with narrowing of the palpebral fissure and globe retraction on attempted adduction, occasionally accompanied by upshoot or down-shoot. The etiopathogenesis of this condition can be explained by a spectrum of mechanical, innervational, neurologic and genetic abnormalities occurring independently or which influence each other giving rise to patterns of clinical presentations along with a complex set of ocular and systemic anomalies. Huber type I DRS is the most common form of DRS with an earlier presentation, while Huber type II is the least common presentation. Usually, patients with unilateral type I Duane syndrome have esotropia more frequently than exotropia, those with type II have exotropia and those with type III have esotropia and exotropia occurring equally common. Cases of bilateral DRS may have variable presentation depending upon the type of presentation in each eye. As regards its management, DRS classification based on primary position deviation as esotropic, exotropic or orthotropic is more relevant than Huber’s classification before planning surgery. Surgical approach to these patients is challenging and must be individualized based on the amount of ocular deviation, abnormal head position, associated globe retraction and overshoots.

Eyelid Dysfunction in Neurodegenerative, Neurogenetic, and Neurometabolic Disease

Eye movement abnormalities are among the earliest clinical manifestations of inherited and acquired neurodegenerative diseases and play an integral role in their diagnosis. Eyelid movement is neuroanatomically linked to eye movement, and thus eyelid dysfunction can also be a distinguishing feature of neurodegenerative disease and complements eye movement abnormalities in helping us to understand their pathophysiology. In this review, we summarize the various eyelid abnormalities that can occur in neurodegenerative, neurogenetic, and neurometabolic diseases. We discuss eyelid disorders, such as ptosis, eyelid retraction, abnormal spontaneous and reflexive blinking, blepharospasm, and eyelid apraxia in the context of the neuroanatomic pathways that are affected. We also review the literature regarding the prevalence of eyelid abnormalities in different neurologic diseases as well as treatment strategies (Table 1).

Management of Duane retraction syndrome with prismatic glasses

PURPOSE

To report the results of using prismatic glasses for Duane retraction syndrome (DRS).

METHODS

Data were obtained from the records of patients who were evaluated during the year 2000 in the Strabismus Unit of the Beyoglu Eye Training and Research Hospital. The average follow-up was 12.2±17.7 months. In all cases, 2 main variables were evaluated: horizontal deviation in the primary position and face turn. Prismatic glasses were provided to patients according to the degree of shift in the primary position.

RESULTS

The mean age of patients was 11.2 years. An analysis was performed on the data collected from 12 cases; 7 patients were females (58.3%) and 5 were males (41.7%), with 11 (91.7%) cases being of type I DRS. All 12 patients had abnormal head posture (face turn) and an angle of mean deviation equaling 10 PD (prism dioptri).

CONCLUSION

Treatment was individualized on a case-by-case basis. Prismatic glasses are useful for eliminating abnormal head posture and ocular misalignment in selected cases.

Audiologic and otologic phenotype in children with Duane's Retraction Syndrome: A rare ophthalmologic disorder

OBJECTIVE

The focus of this study was to evaluate the prevalence, type, and severity of hearing impairment in patients with Duane's Retraction Syndrome and to relate these measures to patient demographics and other otologic and audiologic factors.

STUDY DESIGN

Retrospective AudGen Database analysis

SETTING

Tertiary academic referral center

PATIENTS

Pediatric patients in AudGenDB with a diagnosis of Duane's Retraction Syndrome (DRS).

INTERVENTIONS

Appropriate audiologic, otologic, and demographic data were recorded.

MAIN OUTCOME MEASURE

Seventy-nine patients (n = 79) met inclusion criteria. The first encounter with available audiometric data or the first encounter with hearing loss were documented. Audiograms were stratified by type and severity of hearing loss, and common associated medical issues were documented.

RESULTS

57 children had normal hearing; 22 had hearing loss. 9 ears had pure conductive hearing loss, 1 had pure sensorineural, 14 ears had components of both, and 79 had hearing loss that could not be specified. Multivariate regression revealed episodes of chronic otitis and craniofacial anomalies are associated with worse hearing loss.

CONCLUSION

This study presents a detailed characterization of hearing loss in patients with Duane's retraction syndrome. Conductive and sensorineural hearing loss are both prevalent among these children. Careful and early audiologic evaluation of all patients with DRS is important.

Multiple Ocular and Systemic Disorders in Association with Bilateral Duane's Retraction Syndrome

Duane's retraction syndrome (DRS) is characterized by limitations in horizontal eye movements, globe retraction, and palpebral fissure narrowing on attempted adduction. This disorder is caused by a disturbance in innervation originating in the brain stem and represents <1% of all cases of strabismus. It is postulated that this syndrome is due to an insult during the early weeks (8-10 weeks) of pregnancy and is 10-20 times more frequently associated with other systemic congenital anomalies. This case report of bilateral DRS included bilateral iris-retinal coloboma and congenital heart disease, sensory hearing loss, and inguinal hernia.

Abducens Nerve in Patients with Type 3 Duane's Retraction Syndrome

Background

We have previously reported that the presence of the abducens nerve was variable in patients with type 3 Duane’s retraction syndrome (DRS), being present in 2 of 5 eyes (40%) and absent in 3 (60%) on magnetic resonance imaging (MRI). The previous study included only 5 eyes with unilateral DRS type 3.

Objectives

To supplement existing scarce pathologic information by evaluating the presence of the abducens nerve using high resolution thin-section MRI system in a larger number of patients with DRS type 3, thus to provide further insight into the pathogenesis of DRS.

Data Extraction

A retrospective review of medical records on ophthalmologic examination and high resolution thin-section MRI at the brainstem level and orbit was performed. A total of 31 patients who showed the typical signs of DRS type 3, including abduction and adduction deficit, globe retraction, narrowing of fissure on adduction and upshoot and/or downshoot, were included. The abducens nerve and any other extraocular muscle abnormalities discovered by MRI were noted.

Results

DRS was unilateral in 26 patients (84%) and bilateral in 5 patients (16%). Two out of 5 bilateral patients had DRS type 3 in the right eye and DRS type 1 in the left eye. Of the 34 affected orbits with DRS type 3 in 31 patients, the abducens nerve was absent or hypoplastic in 31 eyes (91%) and present in 3 eyes (9%). Patients with a present abducens nerve showed more limitation in adduction compared to patients with an absent abducens nerve (P = 0.030).

Conclusions

The abducens nerve is absent or hypoplastic in 91% of DRS type 3. Patients with a present abducens nerve showed more prominent limitation of adduction. As DRS type 3 partly share the same pathophysiology with type 1 and 2 DRS, the classification of DRS may have to be revised according to MRI findings.

Duane syndrome: Clinical features and surgical management

OBJECTIVE

To further define the clinical features of Duane syndrome and analyze the surgical outcomes in a subset of these patients.

DESIGN

Retrospective chart review.

PARTICIPANTS

A retrospective chart review of 75 patients with Duane syndrome was performed.

METHODS

Complete ophthalmologic and orthoptic data were extracted from the patients' charts, and patients were classified into group I, II, or III based on forced primary position (PP) deviation. Eighteen patients had strabismus surgery to correct the ocular misalignment with its related abnormal head posture.

RESULTS

Fifty-six percent of the cases were in group I, 16% in group II, and 28% in group III. Fifty-seven percent were female, 91% were unilateral, and 66% had left eye involvement. Ninety-six percent had fissure-narrowing/globe retraction on adduction; 67% had an upshoot, downshoot, or both; and 63% had an A, V, or X pattern. The A patterns correlated with downshoots in 100% of cases, V patterns with upshoots in 88%, and X patterns with upshoots/downshoots in 100%. In the 18 surgical candidates, there were 14 patients in group I, 4 in group II, and 0 in group III. An excellent surgical outcome occurred in 78% of patients and a fair-to-poor outcome in 22%. Upshoots/downshoots and fissure-narrowing/globe retraction patients showed modest improvement after surgery.

CONCLUSIONS

There was a consistent relationship among the type of strabismus, head position, and motility defect. The type of upshoot/downshoot correlated strongly with the A, V, or X pattern. Postoperative improvements of abnormal head posture and PP alignment were achieved in the surgical subset of patients.

Modified Y-splitting Procedure for the Treatment of Duane Retraction Syndrome

OBJECTIVES

To present the outcomes of modified lateral rectus Y-splitting combined with either unilateral or bilateral horizontal rectus recession in Duane Retraction Syndrome (DRS) with significant upshoot or downshoot.

MA­TE­RI­ALS AND MET­HODS

A total of 12 patients including 10 patients with Type I DRS and 2 with Type III DRS underwent modified Y-splitting surgery. Amount of additional recessions varied with the degree of preoperative deviation by intraoperative adjustable suture technique. Preoperatively 3 patients had esotropia (ET), 6 had exotropia (XT), and 3 patients had orthotropia. The mean preoperative deviation was 19.3 prism diopters (PD) (range, 18-20 PD) in ET patients and 19.2 PD (range, 16-20 PD) in XT patients.

RE­SULTS

Postoperatively, all patients had significant correction in horizontal deviation and aligned within 4 PD of orthotropia, and no patients exhibited abnormal head posture. Co-contraction and globe retraction were markedly reduced and abnormal ocular vertical movement disappeared or significantly decreased in all cases. No patients experienced recurrence of ocular motility disorders in the mean 26-month (range, 13-66 months) follow-up period.

CONCLUSION

Modified Y-splitting surgery combined with co-contracting horizontal muscle recession technique seems to be a safe and effective treatment in DRS.

Duane retraction syndrome in a Nigerian child

We report a case of a four year old Nigerian girl who presented to the paediatric unit of our eye clinic with complaints of a squint on looking to the right side and reduction in the size of the right eye when looking to the left. On examination, she had right exotropia in the primary position of gaze. There was limitation of abduction and widening of the palpebral fissure of the right eye on right gaze. On left gaze there was narrowing of the palpebral fissure of the right eye with marked limitation of adduction and an upshoot, or occasionally a downshoot, of the eyeball. This report demonstrates that Duane's syndrome occurs in West Africa. Therefore, detailed examination of all patients with squints is important to ensure accurate diagnosis and appropriate management of the patient's condition.

Interocular symmetry in retinal and optic nerve parameters in children as measured by spectral domain optical coherence tomography

BACKGROUND/AIMS

To report interocular differences in retinal nerve fibre layer (RNFL), optic nerve head and macular parameters in children using spectral domain optical coherence tomography (SD-OCT).

METHODS

This was an observational cross-sectional study including 108 healthy children aged 6-17 years with no ocular abnormality except refractive error. After a comprehensive eye exam and axial length measurement, RNFL, optic nerve and macular thickness measurements were performed using the Cirrus OCT machine. Right and left eyes were compared and interocular differences were computed. Subjects were also divided into two groups based on age (under or over 10 years of age). Main outcome measures were interocular differences and their correlations with age and gender.

RESULTS

The study included 108 children, mean age 10.7 ± 3.1 years; significant interocular differences were observed in both macular and RNFL parameters. The macular thickness analysis revealed interocular differences in the outer nasal and outer inferior quadrants, with left eyes displaying larger values. With respect to RNFL parameters, right eyes displayed thicker nasal and temporal quadrants, and inferior clock hours; left eyes had a thicker superior quadrant. The older age group (>10 years) had more pronounced variation in interocular differences compared with the younger group with less mature visual systems.

CONCLUSIONS

Normal variation in interocular symmetry exists. Our results can contribute to establishing a standard reference for interocular differences in OCT parameters in children aged 6-17 years using the Cirrus device.

8q12 microduplication including CHD7: clinical report on a new patient with Duane retraction syndrome type 3

Background

A novel multiple congenital anomalies syndrome has been recently identified in four patients carrying a 8q12 microduplication sharing the smallest region of overlap (SRO, size 1.6 Mb) including five genes CA8, ASPH, RAB2B, CLVS1 and CDH7. The phenotype is mainly characterized by neurodevelopmental delay, heart defects, facial features and Type 1 Duane anomaly. Increasing dosage of CDH7 was proposed to be responsible for the recurrent pattern of MCA.

Results

High resolution array-CGH analysis identified a 4.2 Mb de novo interstitial duplication of the 8q12.1-q12.3 chromosome region in a boy with developmental delay, dysmorphic features, type 3 Duane anomaly. This duplication includes several genes and spans the SRO.

Discussion

The present case represents a further patient with an interstitial duplication of chromosome 8q12 and several shared clinical features. Although more cases are needed to delineate the full-blown phenotype of 8q12 duplication syndrome, published data and present observations suggest that it results in a clinically recognizable phenotype. The presence of Duane anomaly in four out of five described patients with a 8q12 duplication definitely rules against the possibility of its being a chance finding unrelated to the imbalance and points toward a pathogenic role. Gene content analysis of the duplicated region and review of the literature suggest that gain-of-dosage of the CHD7 gene may be a good candidate for the main clinical features of the syndrome.

Fourth cranial nerve palsy and Brown syndrome: two interrelated congenital cranial dysinnervation disorders?

Based on neuroimaging data showing absence of the trochlear nerve, congenital superior oblique palsy is now classified as a congenital cranial dysinnervation disorder. A similar absence of the abducens nerve is accompanied by misinnervation to the lateral rectus muscle from a branch of oculomotor nerve in the Duane retraction syndrome. This similarity raises the question of whether some cases of Brown syndrome could arise from a similar synkinesis between the inferior and superior oblique muscles in the setting of congenital superior oblique palsy. This hypothesis has gained support from the confluence of evidence from a number of independent studies. Using Duane syndrome as a model, we critically review the accumulating evidence that some cases of Brown syndrome are ultimately attributable to dysgenesis of the trochlear nerve.

Bilateral type-I duane syndrome with multiple anamolies: a case report

The Duane syndrome is a strabismus syndrome which is characterized by congenital non-progressive horizontal ophthalmoplegia which primarily affects the abducens nerve. Approximately 70% of the individuals with the Duane syndrome have an isolated disease. We have described here, a case of bilateral Duane syndrome with associated anamolies.