Comparison of conventional and Hang-back methods of inferior oblique recession in V-pattern strabismus with inferior oblique overaction

AIM:To compare outcomes of conventional and Hangback methods of inferior oblique(IO)recession in V-pattern strabismus with inferior oblique overaction(IOOA).METHODS:Comparative randomized study was conducted consisting of 50 patients,age 6 to 35 y having V-pattern strabismus[>15 prism diopter(PD)]with IOOA.They were divided equally in two groups and underwent IO recession,group A by conventional method and group B by Hang-back method.Parameters evaluated were reduction in V-pattern and IOOA,shift in torsion,improvement in binocular status.Success was a residual V-pattern of less than 10 PD at 1 y of follow up.RESULTS:The mean V-pattern preoperatively and postoperatively at 1 y was 24±5.4 PD and 4.2±3.51 PD in group A and 23.44±6.44 PD and 5.76±3.8 PD in group B respectively.The mean reduction in V-pattern was 20±6.78 PD in group A and 18.2±5.48 PD in group B.The mean correction of IOOA was 18.48±3.13 PD in group A and 16±2.93 PD in group B.Mean shift in extorsion was 3.08±1.8 degree in group A and 3.72±2.14 degree in group B.CONCLUSION:Both the procedures achieve a significant and comparable reduction in V-pattern and IOOA.Hang-back recession being a landmark free surgery eliminates the need for intrascleral suturing thereby reducing the risk of scleral perforation with possible postoperative adjustment of muscle.It may be considered as a good alternative for IO recession in patients of V-pattern strabismus with mild to moderate amount of IOOA.

Reliability of a computerized system for strabismus screening

AIM:To evaluate the reliability of Photo-Hirschberg screening for global strabismus performed by non-specialized personnel.METHODS:Participants at three sites were enrolled.One person at each site was trained in visual acuity measurement and use of the computerized system.Visual acuity was measured,and strabismus testing was performed using two flash photographs.All data from the three primary observers were sent to an experienced assistant researcher,who was blinded to the primary results,for re-evaluation.The primary and re-evaluation results of the Photo-Hirschberg screenings using weighted kappa for agreement were compared.RESULTS:The study included 181 participants(88 males and 93 females)and the results for primary and re-evaluation screenings were corresponded.Ten participants with contrasting results presented with unclear corneal light reflex.Sensitivity and specificity were 100%[95%confidence interval(CI):29.0%-100%]and 99.4%(95%CI:96.6%-100%),respectively,based on the Agresti test of the primary evaluation,considering the re-evaluated classification as true.CONCLUSION:The computerized system can be used for primary strabismus screening by non-specialized personnel,with 98.8%agreement with specialists.However,it cannot be used as a substitute for professional examination.

Defects and asymmetries in the visual pathway of non-human primates with natural strabismus and amblyopia

Strabismus and amblyopia are common ophthalmologic developmental diseases caused by abnormal visual experiences. However, the underlying pathogenesis and visual defects are still not fully understood. Most studies have used experimental interference to establish diseaseassociated animal models, while ignoring the natural pathophysiological mechanisms. This study was designed to investigate whether natural strabismus and amblyopia are associated with abnormal neurological defects. We screened one natural strabismic monkey(Macaca fascicularis) and one natural amblyopic monkey from hundreds of monkeys, and retrospectively analyzed one human strabismus case. Neuroimaging, behavioral,neurophysiological, neurostructural, and genovariation features were systematically evaluated using magnetic resonance imaging(MRI), behavioral tasks, flash visual evoked potentials(FVEP),electroretinogram(ERG), optical coherence tomography(OCT), and whole-genome sequencing(WGS), respectively. Results showed that the strabismic patient and natural strabismic and amblyopic monkeys exhibited similar abnormal asymmetries in brain structure, i.e., ipsilateral impaired right hemisphere. Visual behavior, visual function, retinal structure, and fundus of the monkeys were impaired. Aberrant asymmetry in binocular visual function and structure between the strabismic and amblyopic monkeys was closely related, with greater impairment of the left visual pathway.Several similar known mutant genes for strabismus and amblyopia were also identified. In conclusion,natural strabismus and amblyopia are accompanied by abnormal asymmetries of the visual system,especially visual neurophysiological and neurostructural defects. Our results suggest that future therapeutic and mechanistic studies should consider defects and asymmetries throughout the entire visual system.

Acute acquired concomitant esotropia with congenital paralytic strabismus:A case report

BACKGROUND An unusual case of acute acquired concomitant esotropia(AACE)with congenital paralytic strabismus in the right eye is reported.CASE SUMMARY A 23-year-old woman presented with complaints of binocular diplopia and esotropia of the right eye lasting 4 years and head tilt to the left since 1 year after birth.The Bielschowsky head tilt test showed right hypertropia on a right head tilt.She did not report any other intracranial pathology.A diagnosis of AACE and right congenital paralytic strabismus was made.Then,she underwent medial rectus muscle recession and lateral rectus muscle resection combined with inferior oblique muscle myectomy in the right eye.One day after surgery,the patient reported that she had no diplopia at either distance or near fixation and was found to be orthophoric in the primary position;furthermore,her head posture immediately and markedly improved.CONCLUSION In future clinical work,in cases of AACE combined with other types of strabismus,we can perform conventional single surgery for both at the same time,and the two types of strabismus can be solved simultaneously.

Factors associated with strabismus after cataract extraction and primary intraocular lens implantation in congenital cataracts

AIM:To evaluate factors associated with the development of strabismus after cataract extraction and primary intraocular lens implantation.METHODS:The medical records of 122 patients,aged1.5mo to 9y,who had undergone cataract extraction with primary intraocular lens implantation between January1993 and August 2011 were reviewed.Fourteen patients(17 eyes)with strabismus before cataract surgery were excluded.Patients were divided into those with congenital bilateral cataracts(64 patients,128 eyes)and those with unilateral cataracts(44 patients,44 eyes).The associations between the development of strabismus and age at cataract surgery,pre-and post-cataract extraction corrected distance visual acuity(CDVA),interocular CDVA difference,nystagmus,surgical method,and secondary cataract were evaluated.RESULTS:Factors significantly associated with the development of strabismus included age at cataract surgery(≤1y),preoperative mean CDVA≤20/100,presence of nystagmus in the bilateral cataract group and postoperative interocular CDVA difference】20/70 in the unilateral group.Postoperative CDVA≤20/100 and preservation of posterior capsule,and presence of secondary cataract were significant factors in both groups.CONCLUSION:Children with congenital cataracts should be monitored carefully after cataract surgery for the development of strabismus,especially when they underwent surgery at age≤1y,and they have nystagmus,large postoperative interocular CDVA difference,poor preoperative and postoperative CDVA,preservation of the posterior capsule,or secondary cataract.

Effectivity of intraoperative adjustable suture technique in horizontal strabismus

AIMTo compare the long-term effectivity of intraoperative adjustable suture technique with traditional non-adjustable strabismus surgery.

Clinical characteristics of sibling patients with comitant strabismus

AIM：To investigate the clinical characteristics of sibling patients with comitant strabismus. METHODS：Sibling patients who were diagnosed with comitant strabismus from January 2005 to December 2014 were retrospectively reviewed. Factors including age, sex, types of strabismus, refractive errors, angle of deviation, and coexistence of other strabismus were analyzed. RESULTS：A total of 62 patients（31 pairs of siblings） were included. Of these, 26 pairs had intermittent exotropia, 3 had accommodative esotropia, and 2 had infantile esotropia. There were no pairs with different subtypes of strabismus. The age at first visit was 3.7±2.6y and the mean follow-up period was 30.5±24.1mo. In siblings with intermittent exotropia, there was no difference in age of onset, age at operation, or refractive errors between the first and second-born children. The 20（77%） pairs of siblings with exotropia showed more than 80% concordance of maximum angle of deviation during follow-up. In the 9 pairs in which both siblings had an operation, the final angle of deviation after the operation was 8.2±8.1 prism diopters（PD） in first-born children and 8.6±6.5 PD in second-born children. CONCLUSION：The subtypes of strabismus are the same in all pairs of siblings and clinical characteristics of strabismus are similar between the first and secondborn children. This similarity could be an indicator for the diagnosis of second-born children. Further prospective study including a larger number of sibling patients is needed.

Post-operative strabismus control and motor alignment for basic intermittent exotropia

AIM：To assess strabismus control and motor ocular alignment for basic exotropia surgery at 5y follow-up.METHODS：The medical records of 80 consecutive patients aged less than 17 years of age,who underwent surgery for basic exotropia by a single surgeon between years 2000 to 2009 and completed a minimum of 5y follow-up post-operatively were reviewed.Pre- and post-operative characteristics were documented at 1wk,6mo,1,3 and 5y follow-up.Subjects at 5-year follow-up were assigned to the success group if they had a postoperative angle of deviation within 10 prism diopters of exotropia or within 5 prism diopters of esotropia for distance on prism cover test,and had moderate to good strabismus control.The remaining subjects were assigned to the failure group.RESULTS：Post-operative surgical success at one week was 75%,which decreased to 41% at 5y follow-up.The success group was noted to have more patching pre-operatively（P=0.003）.The duration of patching a day（P=0.020） and total duration of patching preoperatively（P=0.030） was higher in the success group.Surgical success at 1y（P=0.004） and 3y（P=0.002） were associated with higher surgical success at 5y follow-up.CONCLUSION：Post-operative motor alignment and strabismus control for basic exotropia surgery at 1y and beyond is associated with higher exotropia surgery success at 5-year follow-up.There is an association between pre-operative patching and 5-year surgical success of basic intermittent exotropia surgery.

Retinal vessels caliber changes after strabismus surgery：results of 6mo follow-up

AIM：To evaluate the effect of strabismus surgery on retinal vessels calibers with digital color fundus photographs.METHODS：Two hundred consecutive strabismus patients underwent surgery,and 118 patients（female/male,55/63） who finished 6-month follow-up were finally included in this study.Optic disc-centered digital color fundus photographs of both eyes of all patients were taken prior to surgery and 6mo post surgery.The retinal vascular caliber of 116 operated eyes were measured using the computer program IVAN.The operated eyes were divided into 3 groups according to the surgical methods,recession of one muscle,one muscle recession and one muscle folding,one muscle resection and one muscle recession.The effect of number of altered muscles on retinal vessels was analyzed using statistic software SPSS 16.0.RESULTS：The mean age was 12.4±8.6y.Averaged central retinal artery equivalent（CRAE） of all patients was 120.31 ±23.02 μm preoperatively,and 122.87 ±15.93 μm six months after surgery.Averaged central retinal vein equivalent（CRVE） was 171.11 ±31.73 μm preoperatively and175.02±21.00 μm postoperatively.There was no significant difference of averaged CRAE（P=0.22） or CRVE（P=0.19）before and after operation.Averaged arteriole to venule ratio（AVR） was 0.71 ±0.07 before surgery and 0.70±0.07 after surgery.Comparison of preoperative and postoperative retinal vessels calibers among different surgical groups did not show significant differences.Also,there was no advantage of rectus muscle folding to muscle resection.CONCLUSION：Up to 6mo after strabismus surgery,the retinal vascular calibers were not altered.No more than two muscles in one surgery are safe for retinal perfusion.

Clinical features of strabismus and nystagmus in bilateral congenital cataracts

AIM：To evaluate the prevalence,clinical features,and the factors affecting onset of strabismus and nystagmus in patients with bilateral congenital cataracts.METHODS：This study evaluated 116 eyes of 58 patients who underwent lens removal for the treatment of bilateral congenital cataracts between January 1999 and January 2011.The presence and type of strabismus and nystagmus were determined before and after surgery.Type of strabismus and final visual acuity were compared in patients with and without nystagmus.Patients were divided into three groups（orthotropia/orthotropia,orthotropia/strabismus,and strabismus/strabismus） according to their preoperative and postoperative ocular alignment.Age at cataract surgery and associations of nystagmus and primary intraocular lens（IOL） implantation with strabismus were analyzed.RESULTS：Six patients（10.3%） had strabismus preoperatively and an additional 11（19.0%） developed postoperative strabismus.Exotropia was more common than esotropia both preoperatively and postoperatively.Eighteen patients（31.0%） had postoperative nystagmus,with sensory nystagmus being the most common type.Of the 18 patients with nystagmus,10 had strabismus,with exotropia being more common than esotropia.Postoperative visual acuity was poor in patients with nystagmus.Age at cataract surgery and rate of primary IOL implantation were significantly lower,and postoperative nystagmus was more common,in the orthotropia/strabismus group than in the other two groups.CONCLUSION：Exotropia and sensory nystagmus are common in patients with bilateral congenital cataracts.Age at cataract surgery and rate of IOL implantation are lowerand nystagmus more common in patients with postoperative onset of strabismus.Nystagmus is associated with poor visual prognosis.

Identification of rare paired box 3 variant in strabismus by whole exome sequencing

AIM： To identify the potentially pathogenic gene variants that contributes to the etiology of strabismus. METHODS： A Chinese pedigree with strabismus was collected and the exomes of two affected individuals were sequenced using the next-generation sequencing technology. The resulting variants from exome sequencing were filtered by subsequent bioinformatics methods and the candidate mutation was verified as heterozygous in the affected proposita and her mother by sanger sequencing. RESULTS： Whole exome sequencing and filtering identified a nonsynonymous mutation Co434G-T transition in paired box 3 （PAX3） in the two affected individuals, which were predicted to be deleterious by more than 4 bioinformatics programs. This altered amino acid residue was located in the conserved PAX domain of PAX3. This gene encodes a member of the PAX family of transcription factors, which play critical roles during fetal development. Mutations in PAX3 were associated with Waardenburg syndrome with strabismus. CONCLUSION： Our results report that the c.434G-T mutation （p.R145L） in PAX3 may contribute to strabismus, expanding our understanding of the causally relevant genes for this disorder.

Design and Efficacy of Surgery for Horizontal Idiopathic Nystagmus with Abnormal Head Posture and Strabismus

The design and efficacy of surgery for horizontal idiopathic nystagmus （HIN） with abnormal head posture and strabismus were investigated. Different surgical procedures were selected according to the angle of head turn in 44 cases of HIN with abnormal head posture and strabismus. For patients with a head turn of 15° or less, the Anderson procedure was used; the yoke muscles were recessed upon slow-phase. For patients with a head turn between 15° and 25°, the surgery was designed as a Kestenbaum 5-4-4-5 procedure. For patients with a head turn of 25° or more, the surgery was designed as a Parks 5-8-6-7 procedure. The surgery to correct the abnormal head posture was performed on the fixating eye while that to correct the deviation was then performed on the non-fixating eye at the same time. The amount of surgery of the horizontal rectus muscles on the nonfixating eye was sum of the angle of head turn and the degree of deviation, which was calculated as follows： recession/resection amount of medial and lateral rectis/2×5=angle of head turn±degree of deviation. The results showed as follows： （1） Visual acuity： the visual acuity in the primary ocular position increased two lines or more in 35 patients, accounting for 79.55%. Nine patients had no or only one-line improvement, accounting for 20.45% of the entire study population; （2） The degree of deviation in the primary ocular position： 37 cases had a normal primary ocular position or the degree of deviation ≤8△ after surgery, accounting for 84.09%. Six patients had a residual degree of deviation of 8△―15△, accounting for 13.64%. One patient had a residual degree of deviation 〉20△, accounting for 2.27% of the patients examined; （3） Abnormal head posture： 34 patients had a normal head posture or a head turn of less than 5°, accounting for 72.27%. Eight patients had a residual head turn of 5°―15°, accounting for 18.18%. Two patients had a head turn of 15°― 25°, accounting for 4.55%. It was concluded that different surgical procedures based on the angle of head turn and the relationship between deviation and null zone can eliminate anomalous head posture, correct deviation, and improve vision acuity in the primary ocular position simultaneously.

The effects of simultaneous operation on dissociated vertical deviation with horizontal and torsional strabismus

AIM: To investigate the therapeutic effects of simultaneous horizontal and vertical operations on dissociated vertical deviation(DVD) associated with other deviations.METHODS: Forty-five cases of DVD with horizontal and torsional strabismus underwent combined operation were collected retrospectively. All clinical records were analyzed. All patients were followed up for 6 to 24 mo. Wilcoxon signed-ranks test was performed to evaluate the changes of vertical and horizontal deviation. χ~2 test was used to evaluate the changes of binocular visual function. RESULTS: Forty-five cases included 36 patients with intermittent exotropia and binocular inferior oblique overaction(IOOA), 5 patients with concomitant esotropia and binocular IOOA, 4 patients with intermittent exotropia and monocular superior oblique palsy. The superior rectus recession(SRR) combined with horizontal rectus recession and the myectomy of inferior oblique or anterior transposition were operated simultaneously to correct all types of strabismus. There were 43 cases who achieved normal eye position in vertical direction, while 2 cases were with undercorrection of 5~Δ to 6~Δ. In patients with horizontal strabismus, 2 cases of exotropia were with overcorrection of 6~Δ to 8~Δ, 1 case of esotropia was with undercorrection of 6~Δ, and 1 case of monocular superior oblique palsy with compensatory head posture was not significantly improved. The binocular visual function of most patients recovered after operation. The difference of the binocular visual function and eye position were significant compared with that before operation(P<0.05).CONCLUSION: The simultaneous operation on DVD with horizontal and torsional strabismus is successful.

Retinal vascular diameter changes assessed with a computer-assisted software after strabismus surgery

AIM: To quantitatively investigate the retinal vascular diameter changes, analyzing the early and long-term effects on the retinal circulation, with 6-month follow-up. METHODS: Patients underwent horizontal strabismus surger y were enrolled prospectively. Retinal vessel diameters on color fundus photographs were assessed before and 1, 7 d, 6 mo after surgery, using a computerassisted quantitative assessment software. To evaluate the retinal vascular caliber changes, retinal vascular diameters were calculated by means of the Parr–Hubbard formula as the central retinal arteriolar equivalent(CRAE) and central retinal venular equivalent(CRVE). The arteriovenous ratio(AVR) was calculated as CRAE divided by CRVE. RESULTS: A total of 154 eyes of 104 consecutive patients were included. Compared with the data before surgery(121.55±24.67), the mean CRAE(131.18±28.29) significantly increased 1 d af ter surger y(P=0.003), but went back to baseline level at 7 d(118.89±30.35, P=0.15), and 6 mo(123.22±15.32, P=0.60), so did the AVR(P<0.001, P=0.08, P=0.07). As for the mean CRVE, there was no significant difference between those four time points(172.43±33.25, 175.57±36.98, 174.03±40.18, 174.86±20.46, P=1.00). CONCLUSION: Strabismus surgery on both lateral and media rectus muscles, or single media rectus muscle may increase retinal blood flow during the early postoperative period, but would return to normal later. The number of transected anterior ciliary arteries rather might be the main cause of retinal hemodynamic changes early after strabismus surgery.

Progressive restrictive strabismus in an infant

Dear Editor,In this work, we evaluated a special case. Acquired progressive restrictive strabismus is very rare in the infants. We have been accessed to literatures and found only 5 infants had been reported. So, we report a case of progressive restrictive strabismus in a 4-month-old infant and using an anterior orbitotomy approach for the strabismus surgery.

Development and initial validation of the child intermittent Exotropia Questionnaire among child strabismus patients

Objectives:To translate the Child Intermittent Exotropia Questionnaire(Child-IXTQ)from English to Chinese and to evaluate its reliability and validity in Chinese childhood strabismus patients.Method:A consecutive sample of 143 child strabismus patients was recruited from the Department of Ophthalmology at a medical center in Southwest China.In addition,100 visually normal adults and 100 patients with other eye diseases were recruited.The Brislin translation model was followed to develop the Chinese version of Child-IXTQ.Reliability was established using Cronbach's a and test-retest.Validity was established encompassing content validity,construct validity,convergent validity,criterion-related validity and discriminative validity.Results:The correlation coefficients between each item score with the total score ranged from 0.370 to 0.813.Two subscales were extracted by principal component analysis,with a content validity of 0.91.The correlation coefficients between two factor scores with the total score were 0.709 and 0.939.Criterion-related validity was estimated by the correlating the Child-IXTQ with the PedsQL 4.0,and the correlation coefficient was 0.522.In addition,the Child-IXTQ discriminated accurately between strabismus patients and normal children,or children with other eye diseases that possessed good discriminative validity.Cronbach's a coefficient for the internal consistency was 0.907 and the test-retest reliability was 0.962.Conclusions:Our study indicates that the Child-IXTQ is a reliable and valid instrument for assessing the health-related quality of life among children with strabismus.

Clinical efficacy of the partial rectus muscle transportation procedure for paralytic strabismus

AIM:To analyze the clinical efficacy of the partial rectus muscle transportation(PRT)procedure for paralytic strabismus due to single rectus muscle palsy.METHODS:In total,28 patients(31 eyes)who underwent the PRT procedure for paralytic strabismus due to single rectus muscle palsy were retrospectively examined.The following data were collected pre-and postoperatively:angle of deviation in the primary position,presence of diplopia in the primary position,presence of compensatory head posture,and motility of the affected eye.The follow-up period was 6 mo.RESULTS:Based on the preoperative and intraoperative findings,different operations were performed:2 eyes were treated with PRT,26 eyes were treated with PRT combined with the recession of the antagonist muscle(Am)of the paralytic rectus muscle,and 3 eyes were treated with PRT along with the recession of the Am and the yoke muscle(Ym).On the first day after the operation,24 patients were found to be orthophoric in the primary position,without diplopia or abnormal head posture.Moreover,2 patients with monocular lateral rectus muscle palsy had mild overcorrection to 5 prism diopters(PD)and 8 PD,respectively,whereas 2 patients with binocular lateral rectus muscle palsy had mild undercorrection to 8 PD and 10 PD,respectively.During the 6-month follow-up period,the mean deviation was rectified from 96.79±41.21 PD to 0.64±2.38 PD(t=12.48,P<0.001),whereas the deviations in the 2 patients with mild overcorrection were corrected to orthotropia.The mean preoperative limitation of motility improved from-4.55±0.51 to-2.65±0.61(t=-15.13,P<0.001)after 6 mo postoperatively.CONCLUSION:PRT is an effective treatment for complete paralytic strabismus due to single rectus muscle palsy,and can achieve stable clinical efficacy.

Reduced emergence agitation with proparacaine hydrochloride eye drops after general anaesthesia for paediatric strabismus surgery

Purpose:To investigate the effect of proparacaine hydrochloride eye drops on emergence agitation after general anaesthesia for paediatric strabismus surgery.Methods:Paediatric patients(3-12 years-old)receiving strabismus surgery were randomly assigned to receive 1-2 drops of isotonic saline(n=129)or proparacaine hydrochloride(n=129)after surgery.The incidence and degree of emergence agitation were recorded and compared between groups.Results:A significantly lower occurrence of emergence agitation was observed with proparacaine hydrochloride drops compared to isotonic saline(12.4% vs.31.8%;p<0.05).Conclusion:Proparacaine hydrochloride eye drops reduce the incidence of emergence agitation after general anaesthesia for paediatric strabismus surgery.

Long-term chorioretinal changes following strabismus surgery——possible occult needle penetration

Dear Editor,cleral penetration during strabismus surgery was k3 first reported over 50 years ago[1].Early manuscripts reported the incidence of this complication around 10%[1].However,more recent studies suggest that this rate may have decreased[2-3].

Anterior segment optical coherence tomography for identifying muscle status in strabismus surgery

Anterior segment optical coherence tomography （AS-OCT） finds very few indications in the domain of strabismus surgery. Current applications remain restricted to determining limbus-muscle insertion distance and anterior segment changes after strabismus surgery. We discuss two cases of operated strabismus surgery where AS-OCT imaging helped in identifying the operated eye and/or extra ocular muscles （EOM） and thus proved instrumental in planning and management.