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.

Evaluation of dynamic stereopsis in intermittent exotropia patients

AIM: To delineate the characteristics of the dynamic stereopsis test and analyze related parameters in intermittent exotropia [X(T)] patients. METHODS: Fifty-seven X(T) patients and 55 normal subjects were enrolled in this study. The normal and X(T) groups were used to test the reproducibility and reliability of the dynamic stereopsis test, and Bangerter filters with densities of 0.2 were then used to simulate suppression to test for traditional and dynamic stereopsis. In the X(T) group, the measurements included 1) dynamic stereopsis test comprising three parts: motion+disparity, motion only and disparity only; 2) ocular deviation angle; 3) Bagolini striated lens test; 4) disease course; and 5) Titmus stereopsis test. RESULTS: The test-retest reliability of the dynamic stereopsis method was 0.901 in the normal and X(T) groups, and none of the X(T) patients were able to pass the static and dynamic stereopsis tests after using the 0.2 Bangerter filter. The accuracy rate was greater than 80% in the normal group and 31.81%, 36.36%, and 45.45% for the motion+disparity, motion-only and disparityonly components of the traditional test for X(T) patients diagnosed with stereoblindness via traditional tests,respectively. Patients with a long disease course(>1 y) had worse dynamic stereopsis than those with a short disease course(<1 y; P<0.05, Chi-square test). The deviation angle was not correlated with the motion+disparity, disparityonly, or the motion-only test components(all P>0.05, Chisquare test). CONCLUSION: Dynamic stereopsis is preserved in certain X(T) patients diagnosed with stereoblindness via traditional tests. A long disease course was shown to be a negative factor for dynamic stereopsis in X(T) patients which might be associated with worse progression, and provide good references clinically.

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.

Altered intrinsic functional connectivity of the primary visual cortex in youth patients with comitant exotropia: a resting state fMRI study

AIM： To evaluate the differences in the functional connectivity（FC） of the primary visual cortex（V1） between the youth comitant exotropia（CE） patients and health subjects using resting functional magnetic resonance imaging（f MRI） data.METHODS： Totally, 32 CEs（25 males and 7 females） and 32 healthy control subjects（HCs）（25 males and 7 females） were enrolled in the study and underwent the MRI scanning. Two-sample t-test was used to examine differences in FC maps between the CE patients and HCs. RESULTS： The CE patients showed significantly less FC between the left brodmann area（BA17） and left lingual gyrus/cerebellum posterior lobe, right middle occipital gyrus, left precentral gyrus/postcentral gyrus and right inferior parietal lobule/postcentral gyrus. Meanwhile, CE patients showed significantly less FC between right BA17 and right middle occipital gyrus（BA19, 37）.CONCLUSION： Our findings show that CE involves abnormal FC in primary visual cortex in many regions, which may underlie the pathologic mechanism of impaired fusion and stereoscopic vision in CEs.

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.

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.

Clinical risk factors for the development of consecutive exotropia:a comparative clinical study

AIM： To compare a group of patients with consecutive exotropia with patients who had ≤ 10 prism diopters （PD） esotropia or no deviation postoperatively in terms of probable clinical risk factors for the development of consecutive exotropia. METHODS： The study recruited fourteen patients who developed consecutive exodeviation during follow-up period after the correction of esotropia who were categorized as group 1 and thirty-one patients who had still ≤10 PD esotropia or no deviation at the final visit that were considered as group 2. Clinical risk factors leading the development of consecutive deviation were analyzed as the main outcome measures. RESULTS： The mean age of patients was 4.57±3.11y in group 1 and 5.10±3.52y in group 2 （P=0.634）. There was no significant difference of preoperative near and distant deviations among two groups （P =0.835, 0.928 respectively）. The mean amount of medial rectus recession and lateral rectus resection was similar in both groups （P=0.412, 0.648 respectively）. Convergence insufficiency and neurological diseases were more frequent in group 1 （P-0.007, 0.045）. Accompanying neurological disease was found to be as a significant factor increasing the risk of the development of consecutive exotropia significantly [odds ratios （OR）： 5.75 （1.04-31.93）]. CONCLUSION： Accompanying neurological disease appears to be a significant clinical risk factor for the development of consecutive exodeviation during postoperative follow-up after the correction of esotropia. However, larger studies are needed in order to interpret the results to the clinical practice and to ascertain other concurrent risk factors.

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.

Relation between early postoperative deviation and long-term outcome after unilateral lateral rectus recession and medial rectus resection for adult exotropia

AIM： To evaluate the relationship between early postoperative deviation and long-term outcome after unilateral recession and resection surgery for adult exotropia, and to evaluate exotropic shift after surgery.METHODS： This was a retroprospective study involving adult patients with exotropia who underwent unilateral recession and resection surgery and were followed up for at least 2 y. The results were evaluated at 2 y and the final visit. Factors influencing a successful outcome were analyzed. Early postoperative deviation at 1 wk was used to evaluate relationship with long-term outcome. The longterm outcome was classified into 3 groups： successful, acceptable, and poor. Successful outcome was defined as a distance deviation between esodeviation 8 prism diopters（PD） and exodeviation 10 PD.RESULTS： Forty-two patients were enrolled. The mean age at surgery was 26 y（range, 15-49 y）. The median follow-up period was 30 mo（range, 24-108 mo）. Successful outcome was found in 81% of patients at 2 y and in 71% at the final visit. Overcorrection at 1 wk postoperatively was associated with a successful outcome at 2 y. Initial postoperative alignment between orthotropia and esodeviation of 8 PD had the highest chance of a successful outcome（RR=2.2）. The mean postoperative exotropic drift was 4.7 PD at the first month and 9.3 PD at 2 y.CONCLUSION： Initial postoperative deviation can predict long-term outcome after unilateral recession and resection surgery for adult exotropia. The most desirable outcome at 1 wk post-operatively was orthotropia to small esodeviation. Most patients have exotropic drift at a subsequent follow-up, especially in the first month after surgery.

Sensory exotropia subsequent to senile cataract

To evaluate the phacoemulsification and intraocular lens implantation in patients with sensory exotropia subsequent to senile cataract. The authors prospectively studied the role of phacoemulsification and intraocular lens implantation on 25 patients by observing visual acuity, ocular alignment, binocular vision and diplopia pre-, 1 month post- and 3 months post-operation. The patients underwent follow-up for three months. Postoperatively, one patient had a corrected visual acuity of 20/50, and 24 patients had 20/40 or better. The ocular alignment, binocular vision and diplopia were resolved spontaneously. Phacoemulsification and intraocular lens implantation performed together is effective on sensory exotropia subsequent to senile cataract.

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.

Prevalence of intermittent exotropia among primary and secondary school students in Shantou,China

Background: Few prevalence studies on intermittent exotropia(IXT) based on Chinese populations. Furthermore, longitudinal change in this pattern within a local setting has not been reported in the past. This study aims to determine the profile of children with IXT in China.Methods: A total of 7,537 subjects from nine multi-layer primary and secondary schools participated in this investigation. The position of eyes was examined by using Hirschberg test and alternate cover test. The obtained results were classified according to respective features and analyzed statistically. Results: The prevalence of IXT among the participants was 7.98%, accounting for 73.04% of all types of strabismus. Junior high school students had a lower prevalence of IXT than elementary and senior high school counterparts. Logistic regression analysis showed that IXT was mainly found in male pupils at high grades in rural areas and in male secondary students at high grade in urban regions. Conclusions: IXT was shown to be more prevalent than other types of strabismus in Chinese children. Furthermore, the distribution and characteristics of IXT greatly varied among participants.

Clinical Features and Surgical Treatment of A-pattern Exotropia

Purpose: To investigate the clinical characteristics and determine the effective surgical managements of A-pattern exotropia.Methods: Thirty-two patients with A-pattern exotropia underwent superior oblique muscle weakening procedures, medial rectus resection or (and) lateral rectus recession. Pre- and post-operative eye position, deviation angle, superior oblique function and binocular vision were examined and analyzed in the cases.Results: Overaction of the superior oblique muscles (31/32) and underaction of the medial rectus muscle (20/32) were presented in the cases. Postoperatively, a satisfactory ocular alignment was obtained in 28 cases (87.5%), and the A-pattern was corrected in 31 cases (96.9%). Four cases got binocular vision after surgery.Conclusions: As one of the most common forms of A and V patterns, A-pattern exotropia showed clinical characteristics of superior oblique muscle overaction and medial rectus muscle underacion, which should be the primary factors in the etiology of A-pattern exotropia, and superior oblique weakening procedures combined with horizontal surgery should be an effective approach to A-pattern exotropia treatment.

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.

Comparison of contrast sensitivity based on the surgical results for intermittent exotropia

AIM: To compare contrast sensitivity(CS) based on the surgical results for intermittent exotropia(IXT) and to examine the relationship between CS and photophobia.METHODS: Medical records of the patients who underwent bilateral lateral rectus muscle recession for IXT between 4 and 12 years old were reviewed retrospectively. They were categorized based on the surgical results;successful correction group(n=36) and overcorrection group(esotropia ≥10 PD at 3 mo postoperatively, n=18). Using CGT-2000 test for CS was performed binocularly, and subjective reports of photophobia was investigated preoperatively and at 3 mo postoperatively. Objective photophobia was defined as a significant decrease in CS in the presence of glare.RESULTS: Preoperatively, there was no difference in CS between the groups. Postoperatively, under mesopic conditions, significant improvement of CS was observed at 6.3°, 4°, and 2.5° in the successful correction group and at 6.3° and 4° in the overcorrection group, regardless of glare. Under photopic conditions, at all visual angles except 0.64°, improvement in CS was noted in both groups while CS worsened significantly at 0.64° in the overcorrection group postoperatively. At all visual angles under photopic conditions postoperatively, regardless of glare, CS in the overcorrected group was significantly worse than that in the successful correction group, and CS was significantly decreased by addition of glare in both groups. All patients except one(96.4%) in the successful correction group and 8 patients(61.5%) in overcorrection group showed improvement of photophobia postoperatively, which correlated with CS under photopic conditions(P=0.001, 0.03).CONCLUSION: After surgery for IXT, CS under photopic conditions improve at all visual angles except 0.64°, while CS is significantly worse in the overcorrection group postoperatively at 0.64°. Subjective photophobia havesignificant correlation with CS under photopic conditions, and may be used as an objective indicator of photophobia.

Silicone Band in the Surgical Treatment of Manifest Exotropia

Purpose: A silicone band was sutured anteriorly to the edge of the lateral rectus muscle neotendon during recession surgery in order to reduce and delay the reoccurrence after exotropia surgery. Methods: Collected data of 12 patients (8 males and 4 females), aged 7 - 54 years with diagnosis of constant manifest exotropia and mean angle deviation in primary position of 15,04o(sd 1,18) for near and of 13,23o (sd 0,71) for distance. All patients underwent surgical treatment consisting of lateral rectus recession and silicone band apposition in correspondence to the anterior edge of the lateral rectus muscle neotendon. Results: A substantial reduction of the mean angle deviation was observed in all patients after surgery. No adverse bandrelated effects were detected. Conclusion: The silicone band in the surgical treatment of manifest exotropia could be a valuable aid in delaying the relapse thanks to its physical and structural features and to its biocompatibility.

Medial Rectus Muscle Advancement in Consecutive Exotropia

Purpose: Consecutive exotropia is a frequent consequence of surgery for convergent strabismus that may develop at differing rates postoperatively. Several surgical options on horizontal recti have been proposed, but none report a clearly standardized amount of surgery. The present study provides further results of the medial rectus muscle advancement. Methods: Twenty-eight patients, age range 6 - 55 years, who had undergone unilateral or bilateral medial rectus advancement to the physiological insertion, with or without contemporary unilateral lateral rectus muscle recession, were included in the study. Factors leading to the onset of consecutive exotropia were analyzed. Results: After 2 - 3 years, the overall mean angle reduction was 21.3 prismatic diopters (PD) for distance and 22.8 PD for near, with an effectiveness on near vision lower than expected. Only in the 7 cases with a preoperatively larger exotropia at near (of at least 10 PD), the reduction was 17.0 PD for distance and 24.6 PD for near. In unilateral medial rectus muscle advancement, the mean reduction was 14.3 PD for distance and 16.3 PD for near;in bilateral advancement it was 25.8 PD and 25.2 PD respectively. Conclusion: Medial rectus advancement is preferable to other options, especially in cases with convergence deficit, if no excess of divergence or limitation of bulb rotation is present, for which a lateral rectus muscle recession is indicated. Unilateral and bilateral surgeries are useful for exotropia of about 15 PD and 25 PD respectively. The effectiveness depends weakly or not at all by the amount of the previously executed recession.

Effect of Bilateral Lateral Rectus Recession in Intermittent Exotropia according to the Limbus Insertion Distance

Purpose: The aim of this work was the evaluation of the effect of the limbus insertion distance (LID) of the lateral rectus on the surgical results of bilateral lateral rectus recession in intermittent exotropia (IXT) in children and adults. Patients and Methods: This retrospective study included 76 patients. The patients were divided into two groups: group I (age 5 - 13 y), group II (>13 y). All the patients had basic type of intermittent exotropia (IXT) and all of them underwent bilateral lateral recessions according to the preoperative angle of deviation. Intraoperatively, the distance of limbus insertion was measured by surgical calipers. The dose response effect was calculated as the difference between the preoperative angle and postoperative angle divided by total amount of recession and cases were followed at 1 month, 3 months, 6 months and 12 months postoperative. Results: The mean LID in group I was (6.2 ± 0.61 mm) and (6.1 ± 0.55 mm) in group II. The mean dose response (MDR) at 1 year postoperative was (2.32 ± 0.25 mm) in group I and (2.26 ± 0.23) in group II. In patients with LID 6.25 mm who had larger mean dose response (2.52 ± 0.15). There was a significant positive correlation between the LR muscle LID and the dose-response effect. Conclusion: There is positive correlation between the LID of the LR muscle and the recession effect in bilateral lateral rectus recession in treatment of IXT.

Abnormal medial rectus insertion presenting exotropia:a case report and review of the literature

I am Dr. Heeyoung Choi, from the Department of Ophthalmology of Pusan National University Hospital,Busan, Korea. I write to present a case report of abnormal medial rectus insertion presenting exotropia.