Clinical investigation of surgery for intermittent exotropia

Objective： To investigate the time and postoperative binocular vision of strabismus surgery for children with intermittent exotropia （X（T））. Methods： A retrospective investigation was conducted in 80 child patients with intermittent exotropia. Pre- and postoperative angles of deviation fixating at near （33 cm） and distant targets （6 m） were measured with the prolonged alternate cover testing. The binocular function was assessed with synoptophore. Twenty-one patients took the postoperative synoptophore exercise. Results： （1） A week after surgery, 96.2% of the 80 patients had binocular normotopia, while a year after surgery, 91.3% of the 80 patients had binocular normotopia; （2） Preoperatively, 58 patients had near stereoacuity, while postoperatively, 72 patients achieved near stereoacuity （P〈0.05）; （3） Preoperatively, 64 patients had Grade Ⅰ for the synoptophore evaluation and postoperatively, 76 patients achieved Grade Ⅰ. Meanwhile, 55 patients had Grade Ⅱ preoperatively and 72 achieved Grade Ⅱ postoperatively. For Grade Ⅲ, there were 49 patients preoperatively and 64 patients postoperatively （P〈0.05）; （4） Patients of 5-8 years old had a significantly better recovery rate of binocular vision than those of 9-18 years old （P〈0.05）; （5） Patients taking postoperative synoptophore exercise had a better binocular vision than those taking no exercise （P〈0.05）. Conclusions： （1） Strabismus surgery can help to preserve or restore the binocular vision for intermittent exotropia; （2） Receiving the surgery at young ages may develop better postoperative binocular vision; （3） The postoperative synoptophore exercise can help to restore the binocular vision.

Long-term postoperative outcomes of bilateral lateral rectus recession vs unilateral recession-resection for intermittent exotropia

AIM: To discuss the long-term postoperative results of bilateral lateral rectus recession(BLR) and unilateral lateral rectus recession-medial rectus resection(RR) in therapy of intermittent exotropia.METHODS: We retrospectively analyzed 213 cases of intermittent exotropia who underwent surgery between2008 and 2010. The patients were grouped into BLR group and RR group. Motor outcomes were divided into three groups on the basis of the angle of deviation after surgery: overcorrection(esotropia/phoria 】5△), orthophoria(esotropia/phoria ≤5△to exotropia/phoria ≤10△), and undercorrection/recurrence(exotropia/phoria 】10△).Titmus test was used to evaluate stereoacuity, the stereoacuity 【800s of arc meaned the patients had stereopsis. Surgical outcome including motor criteria and sensory status were compared at postoperative 6, 12,24 mo and at 36 mo examination between groups. RESULTS: At 12, 24 mo after surgery, the motor outcomes had no difference(P 】0.05) between groups.However, the motor outcomes at 6, 36 mo were signally different in each group, indicating the success rate in RR group at 6mo was higher than that in BLR group(83.02%vs 82.24%, P 【0.05) but the result was contrary at the 3y examination(60.75% vs 43.40%, P 【0.05). No statistical significance were found in the sensory outcomes between the groups at mean of 3.7y follow-up.CONCLUSION: The motor outcomes in RR group were better than in BLR group at 6mo after surgery, while the3 y outcomes were better in BLR group. This may be due to the recurrence rate of the BLR was lower than the RR group’s.

Survival analysis following early surgical success in intermittent exotropia surgery

AIM:To assess the consecutive recurrence following early success of intermittent exotropia surgery and to determine the clinical factors that affect the survival.METHODS:One hundred and thirty-five patients who underwent intermittent exotropia surgery and experienced early surgical success[≤5 prism diopters(PD)esophoria(E)to≤10 PD exophoria(X)on the postoperative sixth month]were enrolled in this study.Their consecutive survival on the postoperative first year,second year and third year and at the last visit of fourth year or more,and the factors that might affect their survival,were analyzed.The final surgical outcomes after the postoperative fourth year were also investigated by dividing the patients into the success group(≤5 PD E to≤10 PD X)and the failure group(】5 PD esodeviation or】10 PD exodeviation)RESULTS:The survival rates from the Kaplan-Meier analysis were 97.78%,92.89%,83.70%and 50.49%on the postoperative first,second and third years and fourth year or more,respectively.None of the clinical factors was determined to have affected the survival.The amount of the exodrift was largest(2.29 PD)between the first year and the second year,and smallest(1.47 PD)between the fourth year and the last visit.Sixty-three patients had their final visit after the postoperative fourth year,and 29 of them were in the failure group.Twentyfive patients in the failure group had an intermittent exotropia(IXT)of【20 PD with good to fair distant fusion;two had an IXT of【20 PD with poor distant fusion;one had an IXT of≥20 PD with fair distant fusion;and another had delayed-onset consecutive esotropia.The exodeviation on the postoperative sixth month was smaller in the success group than in the failure group(2.81 PD vs 5.86 PD,P=0.012).The reoperation rate for recurrent IXT was 3.7%.CONCLUSION:The survival rate steadily decreases with the exodrift,but the amount of the exodrift decreases with long-term follow-up.The final outcomes demonstrate favorable results via surgical success or small-angle IXT with good fusion in most of the patients.A smaller deviation on the postoperative sixth month is associated with long-term survival.

Surgery at early versus late for intermittent exotropia:a Meta-analysis and systematic review

AIM:To compare the outcomes between early surgery and late surgery for intermittent exotropia(IXT)with a Metaanalysis.METHODS:Scientific databases including PubMed,Embase,Web of Science,Cochrane and China National Knowledge Infrastructure were searched prior to December 16,2019.From this broad database search,we performed some Meta-analysis including eleven independent studies,to further evaluate the outcome(s)when comparing early versus late surgery for IXT.The boundaries between early and late surgery and the surgery methods were not inconsistent,so subgroup analyses were conducted by different boundaries of age at surgery and different surgical approaches.The pooled odds ratios(ORs)and the 95%confidence interval(CI)were estimated according to the random-effects model for high heterogeneity between studies.RESULTS:Eleven retrospective studies were included in this Meta-analysis.No significant difference between early and late surgery was observed for IXT patients(OR_(First follow-up)=0.88,95%CI 0.53-1.44,P=0.61;OR_(Final follow-up)=1.48,95%CI 0.94-2.31,P=0.09).However,sensitivity analysis performed by sequentially omitting individual studies showed that the final follow-up result was not stable.Subgroup analyses revealed that an earlier surgical procedure could lead to a better outcome in the 4-year boundary subgroup as well as the bilateral lateral rectus recession(BLR)subgroup for the final follow-up(OR_(4y)=2.64,95%CI 1.57-4.44,P=0.00;OR_(BLR)=2.25,95%CI 1.36-3.74,P=0.00).CONCLUSION:Early surgery for IXT provides a better long term follow-up outcome when patients are younger than 4 years old or choose the BLR surgical method.

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.

Factors affecting residual exotropia after two muscle surgery for intermittent exotropia

AIM： To study the factors affecting residual exotropia（〉10 PD） at 4-6wk postoperative visit following two rectus muscle surgery for intermittent exotropia [bilateral lateral rectus（LR） recession or unilateral recess resect procedure].METHODS： A retrospective chart review of patients with intermittent exotropia ≤50 PD who underwent two rectus muscle surgery in between Jan. 2011 to Dec. 2013 was performed. Possible factors were compared between patients with residual exotropia（〉10 PD） and successful outcome（within 10 PD of orthotropia） at the 4-6wk postoperative visit. Effect/dose ratio was calculated by dividing the effect of surgery by the total amount（mm） of muscle surgery done.RESULTS： One hundred and fifty-seven patients with mean age of 14y（range 3-53y） were included. Twentyseven patients（17.2%） had residual exotropia at 4-6wk postoperative follow up. Age at surgery（P=0.009） and preoperative deviation for distance（P≤0.001） and near（P=0.001） were identified as important predictors of unsuccessful outcome. The occurrence of residual exotropia was not affected by amblyopia, anisometropia, lateral incomitance, pattern deviation, vertical deviation, type of exotropia or type of surgery done（recess-resect or bilateral LR recession）. The effect/dose ratio was more in deviations 〉40 PD in the both recess-resect and bilateral LR recession type of surgery. The effect/dose ratio was less in patients with residual exotropia as compared to the successful outcome group（1.36 PD/mm vs 2.05 PD/mm in the bilateral LR recession surgery and 1.93 PD/mm vs 2.63 PD/mm in the unilateral recess-resect surgery）.CONCLUSION： Residual exotropia is seen in 17% of patients after two muscle surgery for intermittent exotropia. Patients with older age and larger preoperative deviation have greater chances of developing failure of two muscle strabismus surgery for intermittent exotropia.

Quality of life in adult intermittent exotropia and the risk factors

AIM: To study the quality of life of adult patients with intermittent exotropia(IXT) in China and analyze the factors affecting the quality of life in IXT patients.METHODS: Total y 109 cases of normal eye(control group), 77 cases of IXT(IXT group) and 115 cases of strabismus control group(except IXT) were collected. The quality of life of the patients was assessed by Chinese version of adult strabismus patient’s quality of life scale(CAS-20). The differences of general characteristics, visual function and quality of life were analyzed, and the effects of individual factors and visual function on quality of life of patients with IXT were analyzed.RESULTS: The IXT group had a high proportion of patients with family history, low proportion of patients with amblyopia compared with strabismus control group. The proportion with normal near and far stereopsis of IXT group were lower than that of normal control group. The best corrected visual acuity of IXT group was higher than that of strabismus control group, but lower than the control group. In addition, the median strabismus degree in IXT group was higher than that in other strabismus control group. The median psychosocial scores and median visual function scores of the IXT group was lower than that of the normal control group, but not different from strabismus control group. Occupation status, course of disease, far stereopsis and near stereopsis significantly affected the quality of life in IXT patients.CONCLUSION: Adult IXT patients in China have a certain proportion of family history and lower quality of life, The main factors affecting the quality of life of IXT patients is stereopsis, course of disease and occupation status.

Comparison of bilateral/unilateral lateral rectus recession and unilateral recession-resection for intermittent exotropia:a Meta-analysis

AIM: To compare the effectiveness of unilateral recession-resection(R&R) and bilateral/unilateral recession(BLR/ULR) for treatment of basic type of intermittent exotropia [IX(T)].METHODS: A comprehensive literature search was performed using PubMed, EMBASE, and the Cochrane Library, to identify randomized controlled trials and comparative studies regarding the effectiveness of R&R and BLR/ULR for IX(T). Based on which, a Meta-analysis was then performed in terms of long-term success rate, overcorrection rate, and recurrence rate.RESULTS: Nine studies in total satisfy the specified eligibility criteria. BLR is at disadvantage to R&R at a short-term follow-up [<2 y, OR 0.56(0.33-0.94) for success rate; OR 2.11(1.17, 3.81) for undercorrection rate]. However, BLR achieved a higher success rate [OR 2.49(1.61, 3.86)] and a lower undercorrection rate [OR 0.40(0.23, 0.71)], compared to that of R&R at a long-term followup(>2 y). There is no significant difference was found in overcorrection rate, regardless of the length of follow-up time [OR 0.85(0.41, 1.75)]. In the treatment for small-angle IX(T), the final outcome was significantly different between the groups, demonstrating a more successful alignment [OR 0.37(0.18, 0.74)] and a lower undercorrection [OR 3.50(1.28, 7.26)] in the R&R group than in the ULR group. While for moderate-angle IX(T)(20 PD-25 PD), the effectiveness of R&R and ULR is quite equivalent with similar success rate [OR 1.08(0.65, 1.79)] and undercorrection rate [OR 0.89(0.54, 1.48)]. CONCLUSION: As regard to the effect of BLR and R&R, R&R shows an advantage over BLR at short term. But, BLR is more effective in the long term for the basic typeIX(T) in children. R&R surgery should be a better choice for the treatment of small-angle IX(T) of ≤20 PD than ULR. However, both of ULR and R&R are recommended for moderate-angle IX(T) from 20 PD to 25 PD.

Botulinum toxin augmented bilateral lateral rectus recession versus three muscles surgery in large-angle intermittent exotropia

AIM: To report the surgical outcomes of correcting large angle intermittent exotropia in adult patients by bilateral lateral rectus muscle recession with intraoperative use of botulinum toxin and to compare the results with those of bilateral lateral rectus muscle recession and unilateral medial rectus resection. METHODS: The medical records of patients who underwent surgical correction of large angle intermittent exotropia [exotropia >50 prism dioptre(PD)] were retrospectively reviewed. Two groups of patients were identified;Group Ⅰ(21 patients) had bilateral lateral recti recession augmented with intraoperative botulinum toxin A(BTA) injection into the recessed muscles and group Ⅱ(30 patients) were treated by bilateral lateral recti recession with unilateral medial rectus muscle resection. Preoperative data were extracted for age, gender, refraction, type of exotropia, angle of stereopsis and angle of deviation. The main outcome measures were the postoperative angle of deviation and stereoacuity angle by Titmus test measured at the end of one year of postoperative follow up. RESULTS: By the end of the first postoperative year, 10 patients in group Ⅰ(47.6%) and 20 patients in group Ⅱ(66.7%) achieved esotropia/esophoria <5 PD or exotropia/exophoria <10 PD. The difference in surgical success rate was not statistically significant(P=0.1) but there was a statistically significant higher rate of undercorrection in group Ⅰ(P=0.03). On the other hand, 3 patients in group Ⅰ(14.3%) and 5 patients in group Ⅱ(16.7%) had improved stereopsis;this difference in the sensory outcome was not statistically significant(P=0.8). In the BTA augmented surgery group, good stereoacuity and smaller preoperative angle of deviation were associated with significantly higher surgical success rate(P=0.004, 0.01 respectively). CONCLUSION: BTA augmented bilateral lateral recti recession is associated with higher rate of undercorrection as compared to bilateral lateral recti recession with unilateral medial rectus resection in the correction of large angle intermittent exotropia. The surgical success rate in BTA augmented surgery group is observed to be higher in patients with preoperative smaller angle of deviation and in patients with good stereoacuity.

Advances in surgery procedures for convergence insufficiency-type intermittent exotropia

Intermittent exotropia with convergence insufficiency is defined as a greater exodeviation measured at near than at distance of at least 10 prism diopters and it is harmful to binocular vision at earlier time. This paper mainly introduces three operation patterns including lateral rectus recession(s) with or without a slanting procedure, unilateral lateral rectus recession with medial rectus resection, and medial rectus resection(s) with or without a slanting procedure.

Effect of visual perception training on binocular visual function reconstruction in patients after strabismus surgery

AIM:To explore the effect of visual perception learning software training(VPT)on binocular visual function reconstruction in children with intermittent exotropia after strabismus surgery.METHODS:Ninety children with intermittent exotropia admitted to our hospital from June 2018 to December 2018 were included,and randomly divided into VPT and control groups.Children in the control group received basic binocular vision training,while those in the VPT group received VPT after strabismus surgery.Tertiary visual function,visual perception function,Newcastle Control Score(NCS),and ocular position retraction rate were compared at 3 and 12mo after the surgery.RESULTS:At 3 and 12mo after the surgery,the proportion of simultaneous perception,binocular fusion version and binocular stereo vision in the VPT group was conspicuously higher than that in the control group(P<0.05).After the vision training,the binocular visual perception functions of children in both groups were significantly improved compared with that before training(P<0.05).Interestingly,the grating sharpness,texture perception and texture motion perception in the VPT group were dramatically better than control group(P<0.01).The NCS in the VPT group was significantly lower than that in the control group(P<0.05).The ocular position retraction rate in the VPT group was significantly lower than that in the control group at 12mo(8.89%vs 26.67%,P=0.03).CONCLUSION:VPT effectively promotes binocular visual function reconstruction in intermittent exotropia children after strabismus surgery and reduces the strabismus severity and ocular position retraction rate.

Cortical Deficits are Correlated with Impaired Stereopsis in Patients with Strabismus

In this study,we explored the neural mechanism underlying impaired stereopsis and possible functional plasticity after strabismus surgery.We enrolled 18 stereo-deficient patients with intermittent exotropia before and after surgery,along with 18 healthy controls.Functional magnetic resonance imaging data were collected when participants viewed three-dimensional stimuli.Compared with controls,preoperative patients showed hypoactivation in higher-level dorsal(visual and parietal)areas and ventral visual areas.Pre-and postoperative activation did not significantly differ in patients overall;patients with improved stereopsis showed stronger postoperative activation than preoperative activation in the right V3A and left intraparietal sulcus.Worse stereopsis and fusional control were correlated with preoperative hypoactivation,suggesting that cortical deficits along the two streams might reflect impaired stereopsis in intermittent exotropia.The correlation between improved stereopsis and activation in the right V3A after surgery indicates that functional plasticity may underlie the improvement of stereopsis.Thus,additional postoperative strategies are needed to promote functional plasticity and enhance the recovery of stereopsis.