Basic Type Of Intermittent Exotropia Research Articles

Relevant factors of successful surgery in the basic type of intermittent exotropia

Objective To explore the relevant factors of functionally healing the basic type of intermittent exotropia. Methods A prospective observation study was designed.One hundred and thirty-two cases with basic type of intermittent exotropia in Tianjin Eye Hospital from August 2015 to March 2016.Pre- and post-operation examinations to each patient, including the tests of ocular alignment, Worth four-dot test at 2 m and 33 cm, Titmus, functional visual analyzer (FVA), Frisby Davis distance (FD2) were used to explore the influencing factors of postoperative eye position and stereoscopic reconstruction, and to find the cutoff point of surgery.This study followed the Declaration of Helsinki.This study protocol was approved by Ethic Committee of Tianjin Eye Hospital (No.YKLL-2015-8-21). Written informed consent was obtained from each patient or guardian prior to entering study cohort. Results At 6 months postoperatively, there were 84 cases of orthopedic position, 4 cases of overcorrection and 44 cases of undercorrection.The success rate was 63.6%.The deviation at day 1 and peripheral fusion function were statistically significant to postoperative eye position (b=-0.093, P=0.037; b=0.725, P=0.017). The area under the receiver operating characteristic (ROC) curve was 0.645, which showed that the result of Worth four-dot test at 33 cm had lower diagnostic value.Seventy-two cases with eye position between 0 and + 10 PD at 1 day postoperatively were all successful in eye position at 6 months postoperatively.The postoperative eye position was the influencing factor for postoperative distance stereo with FVA (χ2=4.036, P=0.045). The age of onset and the preoperative distance stereoacuity with FD2 were the influencing factors of postoperative distance stereo reconstruction (b=-0.213, P=0.023; b=0.021, P=0.036). The area under the ROC curve of the age of onset and the preoperative distance stereoacuity with FD2 was 0.257 and 0.752, respectively.The former had no diagnostic value, and the latter had a medium diagnostic value.The best cutoff point was 22.5″ with FD2 at 6 m. Conclusions Success rate of postoperative eye position is affected by the postoperative deviation at day 1.The optimal deviation at post-operation day 1 is 0-10 PD.Postoperative distance stereopsis is improved well and the surgery should be done before the distance stereoacuity is decreased to 22.5″ with FD2 at 6 m. Key words: Exotropia/surgery; Oculomotor muscles/surgery; Binocular vision; Stereopsis

Distance Suppression as a Predictive Factor in Progression of Intermittent Exotropia.

PurposeTo address the natural course of intermittent exotropia with small exodeviations (less than 20 prism diopters [PD]) according to the status of suppression, and to evaluate whether suppression testing at the initial visit can assist in predicting the progression of intermittent exotropia.MethodsClinical records of patients at the Korea University Anam Hospital, Seoul, Korea diagnosed between January 2014 and December 2018 with basic-type intermittent exotropia and initial distance deviations of less than 20 PD, older than four years of age and a minimum of three follow-up visits within a 6-month span were retrospectively reviewed. The participants were divided into two groups, the suppression group and the non-suppression group, based on the Vectogram results at the initial visit. Clinical characteristics, rate of surgery, and rate of progression were compared between the two groups.ResultsA total of 71 patients were included. Among them, 16 patients (22.5%) had visual suppression at the initial visit, while 55 patients (77.5%) had no suppression. At the initial visit, the mean distant angle of deviation was 13.7 ± 3.2 PD (range, 4 to 18 PD) in the suppression group and 12.7 ± 3.4 PD (range, 10 to 18 PD) in the non-suppression group. Ten patients (62.5%) underwent surgery in the suppression group and 12 patients (21.8%) underwent surgery in the non-suppression group (p < 0.01). Eleven patients (68.8%) in the suppression group and 13 (23.6%) in the non-suppression group developed progression (p < 0.01).ConclusionsSuppression testing was important to predict the progression of intermittent exotropia, in patients with exodeviation angles less than 20 PD at the initial visit.

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

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)]. 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. Nine studies in total satisfy the specified eligibility criteria. BLR is at disadvantage to R&R at a short-term follow-up [<2y, 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 follow-up (>2y). 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)]. 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 type IX(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.

A Randomized Trial Comparing Bilateral Lateral Rectus Recession versus Unilateral Recess and Resect for Basic-Type Intermittent Exotropia

To compare long-term outcomes after bilateral lateral rectus recession (BLRc) or unilateral lateral rectus recession combined with medial rectus resection in the same eye (R&R) for primary treatment of childhood intermittent exotropia (IXT). Multicenter, randomized clinical trial. One hundred ninety-seven children 3 to younger than 11 years of age with basic-type IXT, a largest deviation by prism and alternate cover test at any distance of 15 to 40 prism diopters (PD), and near stereoacuity of at least 400 seconds of arc. Random assignment to BLRc or R&R and masked examinations conducted every 6 months after surgery for 3 years. Proportion of participants meeting suboptimal surgical outcome by 3 years, defined as: (1) exotropia of 10 PD or more at distance or near using simultaneous prism and cover test (SPCT); or (2) constant esotropia of 6 PD or more at distance or near using SPCT; (3) loss of 2 octaves or more of stereoacuity from baseline, at any masked examination; or (4) reoperation without meeting any of these criteria. Cumulative probability of suboptimal surgical outcome by 3 years was 46% (43/101) in the BLRc group versus 37% (33/96) in the R&R group (treatment group difference of BLRc minus R&R, 9%; 95% confidence interval [CI], -6% to 23%). Reoperation by 3 years occurred in 9 participants (10%) in the BLRc group (8 of 9 met suboptimal surgical outcome criteria) and in 4 participants (5%) in the R&R group (3 of 4 met suboptimal surgical outcome criteria; treatment group difference of BLRc minus R&R, 5%; 95% CI, -2% to 13%). Among participants completing the 3-year visit, 29% (25 of 86) in the BLRc group and 17% (13 of 77) in the R&R group underwent reoperation or met suboptimal surgical outcome criteria at 3 years (treatment group difference of BLRc minus R&R, 12%; 95% CI, -1% to 25%). We did not find a statistically significant difference in suboptimal surgical outcome by 3 years between children with IXT treated with BLRc compared with those treated with R&R. Based on these findings, we are unable to recommend one surgical approach over the other for childhood IXT.

Changes in Types of Recurrent Intermittent Exotropia after Surgical Correction of Basic Type Intermittent Exotropia

Changes in Types of Recurrent Intermittent Exotropia after Surgical Correction of Basic Type Intermittent Exotropia

Randomized trial comparing bilateral lateral rectus recession versus unilateral recess-resect for basic-type intermittent exotropia

There is no consensus on the preferred surgical treatment for intermittent exotropia (IXT) in children.

Analysis on the clinical efficacy of intermittent exotropia surgery

Objective To analyse the clinical efficacy of intermittent exotropia surgery. Methods Data of 86 cases of intermittent exotropia correcting surgery from July 2010 to August 2014 were collected.According to age, type of binocular and degree of strabismus, the corresponding operative method was designed. The follow-up time was 2 years, the surgical efficacy was analyzed. Results The difference in surgical efficacy was statistically significant between the basic type and the convergence insufficiency type of intermittent exotropia(F=13.513, P=0.031). The difference was statistically significant between the apart strong type and convergence insufficiency type of intermittent exotropia(F=11.513, P=0.039). But the difference was not statistically significant between the apart strong type and the basic type of intermittent exotropia(F=0.442, P=0.679). The differences in preoperative and postoperative binocular visual function were statistically significant(F=288.424, P=0.003). Conclusion The degree and type of strabismus, diopter, binocular visual function, AC/A, age and other factors should be considered. The appropriate treatment is beneficial to improving the efficacy of surgery. Key words: Exotropia, intermittent; Efficacy, surgical; Binocular visual function

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.

Long-Term Results of Symmetrical and Asymmetrical Surgery for Basic-type Intermittent Exotropia in Turkish Patient

Aim: To evaluate the long-term results of symmetrical (i.e., bilateral lateral rectus recession) (BLR rec) and asymmetrical (i.e., unilateral medial rectus resection and lateral rectus recession) (R-R) surgical treatment of patients with a diagnosis of basic-type intermittent exotropia (X(T)). Methods: The patient folders of a total of 65 patients with basic-type X(T) who visited the Ankara Ulucanlar Eye Education and Research Hospital Eye Clinic Strabismus Unit between January 2004 and January 2013 and underwent strabismus surgery were analyzed retrospectively. The patients were evaluated according to the applied surgical method: patients treated using the BLR rec method (Group 1= 25) and patients treated using the R-R method (Group 2= 40). During the last Original Research Article

Distance-near differences in recurrent exotropia after bilateral lateral rectus muscle recessions versus unilateral recession-resection for basic type intermittent exotropia

Distance-near differences in recurrent exotropia after bilateral lateral rectus muscle recessions versus unilateral recession-resection for basic type intermittent exotropia

Surgical outcomes of symmetric and asymmetric surgery for intermittent exotropia with postoperative large early overcorrection

To compare surgical outcomes between bilateral lateral rectus recession (BLR) and unilateral lateral rectus recession-medial rectus resection (RR) for intermittent exotropia with overcorrection of 20 prism diopter (PD) or more on postoperative day 1. A retrospective chart review identified 319 patients who underwent either BLR or RR for primary surgical treatment of intermittent exotropia between July 2008 and June 2011. The patients with basic type intermittent exotropia and overcorrection of 20 PD or more, at either near or distance, on postoperative day 1 and had more than 6 months of follow-up were included. Patients with simultaneous vertical and/or oblique muscle surgery and those with paralytic or restrictive strabismus were excluded. The pre- and post-operative deviation, visual acuity, and near stereoacuity were analyzed. Twenty-four patients were included. The mean postoperative day 1 alignment was 21.5 ± 6.2 PD esotropia at distance, and 13.8 ± 8.0 PD at near. Fourteen patients underwent BLR and 10 underwent RR. Three patients were wearing the base out prism below 15 PD at the last follow-up. The mean duration from the surgery to esotropia below 10 PD was 2.9 ± 1.1 weeks and 8.0 ± 7.1 weeks in the BLR and RR groups, respectively (p = 0.030). All three recurrent patients underwent RR. None of the patients completely lost stereoacuity, postoperatively. In basic type intermittent exotropia with overcorrection of 20 PD or more on postoperative day 1, the overcorrection resolved faster and recurrence rates were lower in BLR group than in the RR group. Consecutive esotropia over 15 PD did not occur in both groups.

Comparison of bilateral lateral rectus recession and unilateral recession resection for basic type intermittent exotropia in children

AimsTo compare surgical outcome of bilateral lateral rectus recession (BLR-rec) and unilateral lateral rectus recession combined with medial rectus resection (R&R) for the basic type of intermittent exotropia (IXT) in...

The tendon width of lateral rectus muscle in predicting the effect of recession: is it just age-related artifact?

The tendon width of the lateral rectus muscle is known to be a useful indicator for estimation of the effect of lateral rectus recession in intermittent exotropia. This study was conducted to investigate whether the tendon width of the lateral rectus would differ according to different age groups. We studied 133 patients ranging from 0 to 51 years of age who had undergone bilateral lateral rectus (BLR) recession for the basic type of intermittent exotropia. A total of 133 patients were divided into four groups; 16 patients who were younger than 2 years old (group 1), 20 patients who were 2-5 years old (group 2), 75 patients who were 5-13 years old (group 3), and 22 patients who were older than 13 years (group 4). Under general anesthesia and before dissection of the muscle tendon from the sclera, the tendon width of the lateral rectus of both eyes near insertion was measured with calipers. The tendon width of each group was as follows: in group 1, 7.84 ± 0.35 mm in the right eye and 7.66 ± 0.44 mm in the left eye; in group 2, 7.70 ± 0.50 mm and 7.65 ± 0.52; in group 3 8.11 ± 0.36, 7.95 ± 0.48. In group 4, measurements were 8.14 ± 0.49 mm and 8.05 ± 0.38 mm, respectively. The difference of tendon width in both eyes was statistically significant in all four groups (P<0.01) and the tendon widths of group 1 and 2 were narrower than that of group 3 and 4. Measurement of tendon width of the lateral rectus muscle for prediction of the effect in intermittent exotropia should be applied in patients ≥ 5 years of age.

Bilateral lateral rectus recession considering the tendon width in intermittent exotropia

The tendon width of the lateral rectus muscle can be a useful indicator of the effect of unilateral lateral rectus recession in intermittent exotropia. The aim of this study was to determine whether the tendon width of lateral rectus would be useful for predicting the effect of bilateral lateral rectus (BLR) recession. We studied a total of 45 patients between 3 and 15 years of age who had undergone bilateral rectus recession for the basic type of intermittent exotropia. The actual effect of lateral recession was calculated by adding the absolute value of the angle of preoperative deviation and the postoperative deviation on the second day and dividing the figure by the total amount of recession. We then calculated the hypothetical effect of lateral rectus recession, considering the tendon width of each eye, and added the effects of both eyes. The hypothetical effects were defined as 3 PD when the tendon width was 8-8.5 mm; 3.5 PD when it was 7-7.5 mm; and 2.5 PD when it was 9-9.5 mm, based upon earlier statistical analysis. We compared both effects using a paired t-test. The mean difference between the actual and the hypothetical effects of BLR recession in all patients was 2.88 PD (P=0.001, range: 0-5.50 PD). However, when the amount of preoperative exodeviation was below 25 PD, the differences were not statistically significant (P=0.086). The tendon width may also be useful indicator in BLR recession if the preoperative exodeviation is below 25 PD.

Binocular Photophobia After Surgical Treatment in Intermittent Exotropia

This study examined the rate of binocular photophobia in intermittent exotropia patients before surgical correction, and the factors affecting this rate. The study also investigated the factors affecting postsurgical disappearance of binocular photophobia. The study involved 162 basic type intermittent exotropia patients who underwent surgical correction between March 2001 and January 2006. The study did not include patients with entropion, congenital cataract, or retinal abnormalities. Parents of the patients were questioned to determine which patients had monocular eye closure in bright light and which had disappeared after bilateral lateral rectus recession. Data was analyzed to determine the factors affecting monocular eye closure before surgery and disappearance after surgery. Of 162 patients, 96 patients had binocular photophobia (60.2%). Photophobia was found to be associated with an angle of exodeviation at distance >25 Prism Diopter (Delta) (p = 0.02), and stereoacuity worse than 60 s (p = 0.02). We defined satisfactory surgical outcome as a deviation of <10 Delta. Of the 81 patients with satisfactory outcomes, 46 showed disappearance of binocular photophobia (53.5%). No factor was found to be associated with loss of binocular photophobia. The angle of strabismus and stereoacuity were found to affect the occurrence of binocular photophobia. Successful surgery treated binocular photophobia in 53.5% of patients. Regardless of the surgical result, clinicians should educate patients in terms of the possibility of persistence of postsurgical photophobia.

Intermittent exotropia: comparative surgical results of lateral recti-recession and monocular recess-resect

To compare the results between recession of the lateral recti and monocular recess-resect procedure for the correction of the basic type of intermittent exotropia. 115 patients with intermittent exotropia were submitted to surgery. The patients were divided into 4 groups, according to the magnitude of preoperative deviation and the surgical procedure was subsequently performed. Well compensated orthophoria or exo-or esophoria were considered surgical success, with minimum of 1 year follow-up after the operation. Success was obtained in 69% of the patients submitted to recession of the lateral recti, and in 77% submitted to monocular recess-resect. In the groups with deviations between 12 PD and 25 PD, surgical success was observed in 74% of the patients submitted to recession of the lateral recti and in 78% of the patients submitted to monocular recess-resect. (p=0.564). In the group with deviations between 26 PD and 35 PD, surgical success was observed in 65% out of the patients submitted to recession of the lateral recti and in 75% of the patients submitted to monocular recess-resect. (p=0.266). Recession of lateral recti and monocular recess-resect were equally effective in correcting basic type intermittent exotropia according to its preoperative deviation in primary position.

Conversion of intermittent exotropia types subsequent to part-time occlusion therapy and its sustainability

To evaluate the effects of part-time occlusion therapy on types of intermittent exotropia and sustainability of converted types. Forty-four and 26 children with basic-type and convergence-insufficiency-type intermittent exotropia, respectively, were evaluated in this study. Upon initial examination, we obtained both distant and near deviating angles using prism cover tests, after correcting for refractive errors. We conducted occlusion of the nondeviating eye for 3 months at 3 h/day and assessed the changes in types of intermittent exotropia. We also observed the changes of deviating angles and sustainability of types after 3 months of cessation of part-time occlusion in patients who did not undergo surgery. Preocclusion deviating angles (mean +/- SD) were determined to be 27.1+/-7.46 prism diopters (PD) on distant measurements and 30.6+/-7.92 PD on near measurements. After 3 months of occlusion, the deviating angles were 25.9+/-9.10 PD on distant measurements and 21.4+/-11.00 PD on near measurements, corresponding to a significant reduction (p=0.005 and p<0.001, respectively). Fourteen patients (32%) suffering from basic type of intermittent exotropia converted to the pseudodivergence excess type. In patients suffering from the basic type who exhibited no changes in type, 9 patients (20%) exhibited reductions on both near and distant angle measurements. Among the convergence insufficiency type of patients, 18 (69%) converted to basic type and 2 patients (7%) converted to the pseudodivergence excess type. In the 15 patients who did not undergo surgery, the converted types were maintained in 6 patients, though the other 9 patients showed regression to the prepatching types after cessation of patching for 3 months. Part-time occlusion therapy resulted in the conversion of the basic and convergence insufficiency types to pseudodivergence excess and basic types in more than half of the intermittent exotropes. Future studies on correlation between type conversion and surgical outcome would be necessary.

Effects of unilateral lateral rectus recession according to the tendon width in intermittent exotropia

To verify the effect of unilateral lateral rectus recession for each millimeter according to the tendon width in intermittent exotropia. A total of 37 patients (37 eyes) of 7 to 11 years of age with basic-type intermittent exotropia and a deviation of 16-25 Prism Diopters (PD) were included in this study. Under general anaesthesia, the tendon width of the lateral rectus of the deviating eye near insertion was measured with calipers, prior to dissection of the muscle tendon from the sclera. Patients underwent 6.5-10 mm unilateral lateral rectus recession. The effect of lateral recession for each millimeter was the absolute value of the angle of preoperative deviation plus postoperative deviation on the second day divided by the total amount of recession. Mean tendon width of the lateral rectus of a deviating eye was 8.3 mm (range: 6.5-9.5). The mean effect per millimeter of unilateral rectus recession in those 37 patient was 2.98+/-0.42 PD (range: 2.4-4.1). The effect of recession was larger in cases in which the tendon width of the lateral rectus was narrower (P=0.000, r=0.72). The tendon width of the lateral rectus muscle can be a useful indicator to estimate the effect of lateral rectus recession in intermittent exotropia.

Treatment of intermittent exotropia.

To study the long-range results of surgically treated intermittent exotropia, 100 consecutive patients have been followed up for an average of 6.1 years. In all cases, the initial procedure was bilateral recession of the lateral rectus muscles. The overall functional cure rate was 78%. To accomplish this result, 27 patients were operated on a second time, 21 for undercorrection and six for overcorrection. A number of patients cooperated very poorly or were lost to follow-up while still under treatment. Had these patients been eliminated from the series, the cure rate would have been greater than 90%. In this study, bilateral recession of the lateral rectus muscles corrected the distant measurement more than the near measurement only with the divergence excess type of deviation. Also, this procedure was not notably more effective with divergence excess than with basic-type intermittent exotropia.