Predictive value of age, angle, and refraction on rate of reoperation and rate of spontaneous resolution in infantile esotropia

Effect of refractive errors on the results of botulinum neurotoxin administration in patients with infantile esotropia

PURPOSE

To investigate the effect of refractive errors on the results of patients followed up with infantile esotropia (IE) and treated with botulinum neurotoxin (BNT) injection.

METHODS

The files of patients with IE who presented to the ophthalmology pediatric ophthalmology unit and underwent BNT injection into both medial rectus muscles between 2019 and 2021 were reviewed retrospectively. Sixty eyes of 30 patients were included in the study. Patients with additional systemic or ocular diseases and those with a history of ocular surgery were excluded. Distance and near deviations were measured (with the prism cover test or Krimsky method) before and at the first, third, and sixth months after BNT injection.

RESULTS

In Group 1 (n = 20) with a spherical equivalent of + 2.0 diopters (D) or less, the mean near and distance deviation value was both 36.8 ± 12.7 prism diopter (PD) before injection. In Group 2 (n = 10) with a spherical equivalent of above + 2.0 D, the near deviation was measured as 35.0 ± 7.1 PD and distance deviation as 31.8 ± 7.9. At six months after BNT injection, the near and distance deviation values were 20.6 ± 12.3 and 20.6 ± 11.6 PD, respectively in Group 1 and 10.1 ± 10.3 and 8.8 ± 10.8 PD, respectively in Group 2. The change in deviation did not statistically significantly differ between the groups (p > 0.05), but the distance and near deviation values were lower in Group 2 at sixth months after BNT injection.

CONCLUSIONS

BNT injection is a preferred method in IE. Higher hypermetropic values seem to increase the success of BNT injection.

Interventions for infantile esotropia

BACKGROUND

Infantile esotropia (IE) is the inward deviation of the eye. Various aspects of the clinical management of IE are unclear; mainly, the most effective type of intervention and the age at intervention.

OBJECTIVES

To examine the effectiveness and optimal timing of surgical and non-surgical treatment options for IE to improve ocular alignment and achieve or allow the development of binocular single vision.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, one other database, and three trials registers (November 2021). We did not use any date or language restrictions in the electronic searches for trials.  SELECTION CRITERIA: We included randomized trials and quasi-randomized trials comparing any surgical or non-surgical intervention for IE.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology and graded the certainty of the body of evidence for six outcomes using the GRADE classification.

MAIN RESULTS

We included two studies with 234 children with IE. The first study enrolled 110 children (mean age 26.9 ± 14.5 months) with an onset of esotropia before six months of age, and large-angle IE defined as esotropia of ≥ 40 prism diopters. It was conducted between 2015 and 2018 in a tertiary care hospital in South Africa. It compared a maximum of three botulinum toxin injections with surgical intervention of bimedial rectus muscle recession, and children were followed for six months. There were limitations in study design and implementation; the risk of bias was high, or we had some concerns for most domains.  Surgery may increase the incidence of treatment success, defined as orthophoria or residual esotropia of ≤ 10 prism diopters, compared with botulinum toxin injections, but the evidence was very uncertain (risk ratio (RR) of treatment success 1.88, 95% confidence interval (CI) 1.27 to 2.77; 1 study, 101 participants; very low-certainty evidence). The results should be read with caution because 23 children with > 60 prism diopters at baseline in the surgery arm also received botulinum toxin at the time of surgery to augment the recessions. There was no evidence of an important difference between surgery and botulinum toxin injections for over-correction (> 10 prism diopters) of deviation (RR 0.29, 95% CI 0.06 to 1.37; 1 study, 101 participants; very low-certainty evidence), or additional interventions required (RR 0.66, 95% CI 0.36 to 1.19; 1 study, 101 participants; very low-certainty evidence). No major complications of surgery were observed in the surgery arm, while children experienced various complications in the botulinum toxin arm, including partial transient ptosis in 9 (16.7%) children, transient vertical deviation in 3 (5.6%) children, and consecutive exotropia in 13 (24.1%) children. No other outcome data for our prespecified outcomes were reported.  The second study enrolled 124 children with onset of esotropia before one year of age in 12 university hospitals in Germany and the Netherlands. It compared bilateral recession with unilateral recession surgeries, and followed children for three months postoperatively. Very low-certainty evidence suggested that there was no evidence of an important difference between bilateral and unilateral surgeries in the presence of binocular vision (numbers with event unclear, P = 0.35), and over-correction (RR of having exotropia 1.09, 95% CI 0.45 to 2.63; 1 study, 118 participants). Dissociated vertical deviation, latent nystagmus, or both were observed in 8% to 21% of participants.

AUTHORS' CONCLUSIONS

Medial rectus recessions may increase the incidence of treatment success compared with botulinum toxin injections alone, but the evidence was very uncertain. No evidence of important difference was found between bilateral surgery and unilateral surgery.  Due to insufficient evidence, it was not possible to resolve the controversies regarding type of surgery, non-surgical intervention, or age of intervention in this review. There is clearly a need to conduct good quality trials in these areas to improve the evidence base for the management of IE.

Strabismus controversies that inspired the foundation of the Donders Society for Strabology and of the journal Strabismus

The Donders Society for Strabology and the journal Strabismus were founded in 1984 and 1992 to (i) stimulate scientific exchange, (ii) bridge the gap between clinical strabismus and neurophysiology by covering the two fields in a single journal and (iii) provide a forum for multicenter studies. They were inspired by two controversies on the treatment of strabismus, whether accommodative esotropia should be treated with glasses or not and whether infantile esotropia should be operated in the first years of life to preserve or reinstate binocular vision. Key assumptions in the theory leading to the former controversy were that the angle between the oblique muscle plane and the sagittal plane was small in strabismus patients causing excyclotropia, that hemiretinal suppression occurred when the left and right halves of the visual fields were no longer aligned because of excyclotropia and that binasal or bitemporal suppression disturbed the balance of the optomotor reflexes and thereby caused esotropia or exotropia. Hemiretinal suppression also disturbed accommodation related to the development of hyperopia, which did not cause esotropia and could worsen by wearing glasses. The Donders Society for Strabismology was founded in 1984, and expanded with Flemish pediatric ophthalmologists and orthoptists two years later. A survey gauging the need for a European journal on strabismus and amblyopia in 1985 got favorable responses from strabismologists from continental Europe. However, a proposal by Aeolus Press to the European Strabismological Association to adopt or endorse such journal was turned down in 1989 and by the International Strabismological Association in 1990. In 1992 candidate editors were invited to start the journal Strabismus without adoption by a professional organization and founding meetings took place in April and May, 1992. Regarding the three goals set, it can be said that both the Donders Society for Strabology and the journal Strabismus have stimulated scientific exchange to a high degree, but they have bridged the gap between clinical strabismus and neurophysiology only modestly. Strabismus did successfully provide a forum for the multicenter Early vs. Late Infantile Strabismus Surgery Study.

A Novel Method Ensuring an Immediate Target Angle After Horizontal Strabismus Surgery in Children

Purpose

Pediatric strabismus surgery has low success rates and high reoperation rates because of difficult alignment measurements and the nature of different strabismus types. Furthermore, adjustable sutures are not easily employed in children on an OPD basis.

Methods

This was a retrospective comparative case study of children less than 12 years old who underwent strabismus surgery and were followed up at least 6 months postoperatively. We proposed a novel method that combines adjustable sutures and corneal light reflexes in regular strabismus surgery to improve surgical results. Efficacy and safety were evaluated and compared with those in a regular fixed-suture group.

Results

In total, 128 children (88: exotropia and 41: esotropia) in the novel method group (Group 1) and 109 (71: exotropia and 38: esotropia) in the regular fixed-suture group (Group 2) were enrolled. The primary outcome was the immediate target angle (for esotropia within 4 PD of orthotropia and exotropia within 8 PD of esotropia within the first week postoperatively); the secondary outcome was success at the 6-month visit (angle of deviation < 10 PD). Consequently, there was a significantly higher proportion of achieving the immediate target range and success rate in both exotropic and esotropic patients in Group 1 than in Group 2. A significantly lower reoperation rate was also demonstrated in Group 1. No complications were noted in either group.

Conclusions: The novel method enabled a higher proportion of subjects to achieve an immediate target range and success rate and a lower chance of reoperation among both esotropic and exotropic patients.

Timing of surgery in essential infantile esotropia - What more do we know since the turn of the century?

This review summarizes the results and interpretations of studies pertaining to the long-standing debate regarding the timing of surgery in infantile esotropia, more recently referred to as essential infantile esotropia. A systematic search of studies from the year 2000 onward pertaining to the timing of surgery in infantile esotropia as listed in PubMed, Google Scholar, and the Cochrane database was performed. Appropriate cross-references from the articles were also included. Data collected included demographics, presentation, time of surgery, complications, and outcomes. Very early surgery, that is, within 6 months of the onset of infantile esotropia, offers significant advantages in terms of the quality of stereopsis and binocular vision as well as promoting the development of cortical visual processing, thereby benefiting cortical development in human infants. However, the postoperative alignment was not found to be significantly different in the very early, early, or late surgery groups. The reduction in the incidence of manifest dissociated vertical deviation postoperatively in the very early surgery group also showed measurable benefits. The results of this recent literature review demonstrated that very early surgery, within 6 months of misalignment, showed demonstrable benefits in essential infantile esotropia.

Essential Infantile Esotropia: A Course of Treatment From Our Experience

Background: Essential infantile esotropia (EIE) is the most common type of childhood esotropia. Although its classical approach is surgical, less invasive techniques have been proposed as an adjunct or alternative to traditional surgery. Among them, chemodenervation with botulinum toxin (BT) has been investigated, showing variable and sometimes conflicting results. Objectives: To compare the outcomes of bilateral BT injection and traditional surgery in a pediatric population with EIE in order to optimize and standardize the therapeutic approach. Other purposes are to evaluate whether early intervention may prevent the onset of vertical ocular deviation (which is part of the clinical picture of EIE) and/or influence the development of fine stereopsis, and also to assess changes in refractive status over time among the enrolled population. Methods: A retrospective consecutive cohort study was conducted in 86 children aged 0-48 months who underwent correction of EIE. The primary intervention in naïve subjects was either bilateral BT injection (36 subjects, "BT group") or strabismus surgery (50 subjects, "surgery group"). Results: Overall, BT chemodenervation (one or two injections) was effective in 13 (36.1%) subjects. With regard to residual deviation angle, the outcomes at least 5 years after the last intervention were overlapping in children receiving initial treatment with either injection or surgery; however, the success rate of primary intervention in the surgery group was higher, and the average number of interventions necessary to achieve orthotropia was smaller. Both early treatment with chemodenervation and surgery at a later age were not found to prevent the onset of vertical ocular deviation, whereas, surprisingly, the percentage of subjects developing fine stereopsis was higher in the surgery group. Finally, with regard to the change in refractive status over time, most of the subjects increased their initial hyperopia, whereas 10% became myopic. Conclusions: Our data suggest that a single bilateral BT injection by age 2 years should be considered as the first-line treatment of EIE without vertical component; whereas, traditional surgery should be considered as the first-line treatment for all other cases and in subjects unresponsive to primary single BT injection.

Gene expression profile of extraocular muscles following resection strabismus surgery

This paper aims to identify key biological processes triggered by resection surgery in the extraocular muscles (EOMs) of a rabbit model of strabismus surgery by studying changes in gene expression. Resection surgery was performed in the superior rectus of 16 rabbits and a group of non-operated rabbits served as control. Muscle samples were collected from groups of four animals 1, 2, 4 and 6 weeks after surgery and processed for RNA-sequencing and immunohistochemistry. We identified a total of 164; 136; 64 and 12 differentially expressed genes 1, 2, 4 and 6 weeks after surgery. Gene Ontology enrichment analysis revealed that differentially expressed genes were involved in biological pathways related to metabolism, response to stimulus mainly related with regulation of immune response, cell cycle and extracellular matrix. A complementary pathway analysis and network analysis performed with Ingenuity Pathway Analysis tool corroborated and completed these findings. Collagen I, fibronectin and versican, evaluated by immunofluorescence, showed that changes at the gene expression level resulted in variation at the protein level. Tenascin-C staining in resected muscles demonstrated the formation of new tendon and myotendinous junctions. These data provide new insights about the biological response of the EOMs to resection surgery and may form the basis for future strategies to improve the outcome of strabismus surgery.

The relationship between abduction deficit and reoperation among patients with infantile esotropia

AIM

To determine the relationship between abduction deficit and reoperation among patients with infantile esotropia (IET).

METHODS

The records of 216 patients (432 eyes) with IET who underwent surgery, from 2010 to 2015 were studied. Patients with IET whose deviation appeared before 6mo of age and had stable preoperative deviation in two examinations with at least 2wk apart and a minimum 3mo postoperative follow up were included. Cases with early onset accommodative esotropia, congenital cataract, retinopathy of prematurity (ROP), manifest nystagmus, fundus lesions, neurologic and ophthalmic anomalies, 6^th nerve palsy and Duane's syndrome were excluded. Preoperative abduction deficit was considered from -1 to -3 grading scale. Three months after surgery, children were classified into no-need reoperation [deviation≤15 prism diopters (PD)], and need-reoperation groups (deviation>15 PD).

RESULTS

In this retrospective study, 117 female and 99 male patients with the mean surgical age of 4.7±6.4y were included. Reoperation rate was 33.3% and 16.0% in IET patients with and without abduction deficit, respectively in patients who had a history of late surgery. Abduction deficit increased the odds of reoperation by 82% [OR=1.82, 95% confidence interval (CI) =1.05 to 3.19, P=0.003] in patients who had a history of late surgery (>2 years old, P=0.021). Abduction deficit was improved significantly after operation (P<0.001).

CONCLUSION

Based on our results, abduction deficit can be considered as a risk factor of reoperation in IET patients who are operated at the age of more than 2y.

Essential infantile esotropia with inferior oblique hyperfunction: long term follow-up of 6 muscles approach

AIM

To evaluate long term follow-up (10y) of 6 muscle surgical approach in essential infantile esotropia (EIE).

METHODS

A 6 muscle approach to EIE was retrospectively evaluated in patients with inferior oblique (IO) hyperfunction and lateral rectus (LR) pseudoparalysis, who underwent surgery at different ages. Different clinical characters were analyzed pre- and postoperatively, in patients who underwent a 6 muscles approach ≤4 years of age. All patients underwent a multiple muscles approach: bilateral medial recti (MR) recession (4-5 mm), bilateral LR resection (lower than 7 mm) and bilateral IO recession and anteroposition. Of 108 children with preoperative angle ≥+30 prism diopters (PD) and IO hyperfunction were selected from larger cohort of patients (n=213, 103 females and 110 males) after excluding patients with: angle variability, who underwent reoperation and with incomplete follow up. Preoperative assessment and complete orthoptic examination were performed. Follow-up was performed 3mo, 2, 5 and 10y after surgery. Statistical analysis was performes using SAS statistical software package (version 9.1, SAS Institute Inc., Cary, NC, USA).

RESULTS

Ten years follow up data analysis showed the following percentage of orthotropic patients: (0 PD): 3mo, 22.2%; 2y, 16.7%; 5y, 25.0% and 10y, 27.8%. A slight, significant (P<0.01), increase of 2y follow up residual deviation was found when compared to 3mo one. Stationary surgical results is reported during time, with a trend of mean residual deviation reduction (P=0.04).

CONCLUSION

Our results confirm the reliability of multiple muscles surgical approach in the treatment of patients affected by EIE with OI hyperfunction.

Surgical Results of Symmetric and Asymmetric Surgeries and Dose-Response in Patients with Infantile Esotropia

Objectives:

To evaluate the results of symmetric and asymmetric surgery and responses to surgical amounts in patients with infantile esotropia.

Materials and Methods:

The records of patients with infantile esotropia who underwent bilateral medial rectus recession (symmetric surgery) and unilateral medial rectus recession with lateral rectus resection (asymmetric surgery) were analyzed. The results of the cases with symmetric (group 1) and asymmetric (group 2), successful (group 3) and failed (group 4) surgeries were compared, and responses to the amount of surgery were investigated.

Results:

There were no significant differences between group 1 (n=71) and group 2 (n=13) cases in terms of gender, refraction, preoperative distance deviation, anisometropia and postoperative deviation angles, binocular vision, surgical success or follow-up period (p>0.05). The rate of amblyopia, near deviation and amount of surgery were higher in group 2 cases (p<0.05). Between group 3 (n=64) and group 4 subjects (n=20), no significant differences were detected in terms of gender, surgical age, refraction, amblyopia, anisometropia, preoperative deviation angles, the number of symmetric and asymmetric surgeries, the amount of surgery, or postoperative binocular vision (p>0.05). The average postoperative follow-up period was 15.41±19.93 months (range, 6-98 months) in group 3 cases and 40.45±40.06 months (range, 6-143 months) in group 4 cases (p=0.000). No significant difference was detected in the amount of deviation corrected per 1 mm of surgical procedure between the successful cases in the symmetric and asymmetric groups (p>0.05).

Conclusion:

Symmetric or asymmetric surgery may be preferable in patients with infantile esotropia according to the clinical features. It is necessary for every clinic to review its own dose-response results.

Infantile esotropia: risk factors associated with reoperation

The aim of this study was to identify clinical and demographic factors associated with misalignment after first surgery performed on children affected by infantile esotropia to evaluate the reoperation rate. A retrospective study was carried out, analyzing data from 525 children who underwent bilateral medial recti recession, bilateral lateral recti resection, and inferior oblique recession and anteroposition by the same surgeon (AM). Postoperative evaluation included assessment of motor alignment at approximately 3 months, 6 months, 1 year, and 5 years. Statistical analysis was performed with a logistical regression model in which the dependent variable was the presence/absence of reoperation. We found that late surgery (after 3 years of age) and a family history of strabismus are associated with a higher risk of reoperation, while some clinical factors, including some classically associated with worst motor outcome as preoperative angle, dissociated vertical deviation, and amblyopia, did not influence the incidence of reoperation in infantile esotropia. Male patients and patients with hyperopia in preoperative examinations have a significantly decreased reoperation rate.

Essential Infantile Esotropia: Postoperative Sensory Outcomes of Strabismus Surgery

BACKGROUND

The optimum age for Essential Infantile Esotropia surgery is a controversial subject. Sensory status was evaluated in patients who underwent surgery at different ages in a retrospective study. The setting of the study is the ophthalmology department of a teaching hospital.

METHODS

Different clinical characters were analyzed pre- and postoperatively; nine different surgeries were performed. A total of 188 patients presented valid postoperative sensorial data, divided in two groups: surgery at ≤2 years (n=69) or >2 years (n=119). Sensory status was dichotomized in binocular single vision (BSV) and exclusion. Univariate differences were assessed with the chi-square test (or Fisher exact test). To identify the independent role of factors associated with the sensory status, all variables showing in univariate analyses a significant association (p<0.05) with the outcome variable were entered into a multivariate logistic regression model. All statistical tests were two-sided.

RESULTS

Multivariate analysis confirmed that children operated >2 years were 0.4 times less likely to obtain BSV compared with children operated at ≤2 years (AOR. 0.38, 95% C.I. 0.17-0.89, p=0.025). Patients operated on by OO MR rec.+ OO LR res. + OO IO rec.-ap. (intervention type 6) were about 11 times more likely to have BSV than those by OO rec.MR + unilateral res. LR (operation type 2); AOR.: 10.67, 95% C.I.: 1.34 - 85.29, p=0.026). Twenty-nine patients (12.1%) operated at ≤2 years of age underwent a reoperation, compared to 33 (8.6%) who underwent surgery after two years (p>0.05).

CONCLUSIONS

Our findings suggest to perform EIE surgery between age 1 and 2 and, when indicated, to prefer a six-muscle approach in order to achieve a better sensory function.

The Effect of Achieving Immediate Target Angle on Success of Strabismus Surgery in Children

PURPOSE

To determine if achieving the ideal postoperative target range increases the long-term success of pediatric strabismus surgery.

DESIGN

Interventional case series.

METHODS

Children below 12 years old with horizontal strabismus who underwent surgical correction by recession, resection, advancement, or a combination of both between 1996 and 2011 were included. Alignment was measured within 1 week and at a minimum of 6 months after surgery. The ideal postoperative target range was defined as 0-8 prism diopters (PD) of esotropia in exotropic patients and within 4 PD of orthotropia in esotropic patients measured within 1 week after the surgery. Success was defined as a measurement within 10 PD of orthotropia at the latest postoperative visit. The main outcome measures were surgical success rate and the factors affecting it.

RESULTS

We included 352 patients with mean follow-up of 18 months. Overall, patients within the target range had a higher success rate than those outside it (75.6% vs 57% P = .0004). This was highly significant for exotropia (P = .0002) but not for esotropia (P = .4). Multiple regression analysis revealed that being within target range was the strongest predictor of long-term success (odds ratio [OR] = 2.3, range 1.4-3.7). Overall, surgeries on patients with esotropia were more likely to be successful than on those with exotropia (OR = 1.9, range 1.2-3), and premature patients had poorer outcomes (OR = 0.2, range 0.1-0.8).

CONCLUSION

Achieving the ideal target range within 1 week after surgery is associated with a high rate of long-term success in exotropia surgery in children.

Surgical treatment for residual or recurrent strabismus

Although the surgical treatment is a relatively effective and predictable method for correcting residual or recurrent strabismus, such as posterior fixation sutures, medial rectus marginal myotomy, unilateral or bilateral rectus re-recession and resection, unilateral lateral rectus recession and adjustable suture, no standard protocol is established for the surgical style. Different surgical approaches have been recommended for correcting residual or recurrent strabismus. The choice of the surgical procedure depends on the former operation pattern and the surgical dosages applied on the patients, residual or recurrent angle of deviation and the operator's preference and experience. This review attempts to outline recent publications and current opinion in the management of residual or recurrent esotropia and exotropia.

Interventions for infantile esotropia

BACKGROUND

Infantile esotropia (IE) is the inward deviation of the eye. Various aspects of the clinical management of IE are unclear; mainly, the most effective type of intervention and the age at intervention.

OBJECTIVES

The objective of this review was to assess the effectiveness of various surgical and non-surgical interventions for IE and to determine the significance of age at treatment with respect to outcome.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 5), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE, (January 1950 to June 2013), EMBASE (January 1980 to June 2013), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to June 2013), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 10 June 2013. We manually searched the conference proceedings of the European Strabismological Association (ESA) (1975 to 1997, 1999 to 2002), International Strabismological Association (ISA) (1994) and American Academy of Paediatric Ophthalmology and Strabismus meeting (AAPOS) (1995 to 2003). Efforts were made to contact researchers who are active in the field for information about further published or unpublished studies.

SELECTION CRITERIA

We included randomised trials comparing any surgical or non-surgical intervention for infantile esotropia.

DATA COLLECTION AND ANALYSIS

Each review author independently assessed study abstracts identified from the electronic and manual searches.

MAIN RESULTS

No studies were found that met our selection criteria and therefore none were included for analysis.

AUTHORS' CONCLUSIONS

The main body of literature on interventions for IE are either retrospective studies or prospective cohort studies. It has not been possible through this review to resolve the controversies regarding type of surgery, non-surgical intervention and age of intervention. There is clearly a need for good quality trials to be conducted in these areas to improve the evidence base for the management of IE.

The prevalence of reoperation and related risk factors among patients with congenital esotropia

PURPOSE

To determine the prevalence rate and related risk factors of reoperation among patients with congenital esotropia.

METHODS

One hundred fifty-seven children with congenital esotropia were divided into two groups after at least one operation: children with deviation within 10 PD (n = 89; success group) and those with deviation greater than 10 PD or history of reoperation (n = 68; failure group). The relationship of risk factors such as age at first operation and primary congenital esotropia of less than 30 or more than 50 PD and accompanying factors such as inferior oblique muscle overaction (> +1), dissociated vertical deviation, lateral rectus muscle underaction, and A-V pattern with reoperation were studied. Final sensory status of children 5 years and older was evaluated by Worth 4-dot and Titmus tests.

RESULTS

Reoperation was indicated in 32.4% of children who had residual esotropia greater than 15 PD after 3 months following their first operation. Congenital esotropia greater than 30 PD (P = .002) and lateral rectus muscle underaction of −1 to −2 (P < .005), were statistically different between the two groups. Initial operation at younger than 3 years was more likely to achieve gross stereopsis in children 5 years and older (P = .032).

CONCLUSION

Congenital esotropia greater than 30 PD and lateral rectus muscle underaction were found to be risk factors of reoperation.

Best age for surgery for infantile esotropia

Infantile esotropia (IE) is defined as an esotropia before the age of 6 months, with a large angle, latent nystagmus, dissociated vertical deviation, limitation of abduction, and reduced binocular vision, without neurological disorder. Prematurity, low birth weight, and low Apgar scores are significant risk factors for IE. US standard age of first surgery is 12-18 months, in Europe 2-3 years. The only study to date with prospectively assigned early- and late-surgery groups and evaluation according to intention-to-treat, was the European Early vs. Late Infantile Strabismus Surgery Study (ELISSS). In that study 13.5% of children operated around 20 months vs. 3.9% (P = 0.001) of those operated around 49 months had gross stereopsis (Titmus Housefly) at age 6. The reoperation rate was 28.7% in children operated early vs. 24.6% in those operated late. Unexpectedly, 8% in the early group vs. 20% in the late group had not been operated at age 6, although all had been eligible for surgery at baseline at 11 SD 3.7 months. In most of these children the angle of strabismus decreased spontaneously. In a meta-regression analysis of the ELISSS and 12 other studies we found that reoperation rates were 60-80% for children first operated around age 1 and 25% for children operated around age 4. Based on these findings, the endpoints to consider when contemplating best age for surgery in an individual child with IE should be: (1) degree of binocular vision restored or retained, (2) postoperative angle and long-term stability of the angle and (3) number of operations needed or chance of spontaneous regression. IE is characterized by lack of binocular connections in the visual cortex that cannot develop, e.g. because the eyes squint, or do not develop, e.g. after perinatal hypoxia. As the cause of IE, whether motor or sensory, is a determinant of surgical outcome, a subdivision of IE according to cause is needed. As similarities exist between IE and cerebral palsy we propose to adapt the working definition formulated by the Surveillance of Cerebral Palsy in Europe and define IE as "a group of permanent, but not unchanging, disorders with strabismus and disability of fusional vergence and binocular vision, due to a nonprogressive interference, lesion, or maldevelopment of the immature brain, the orbit, the eyes, or its muscles, that can be differentiated according to location, extent, and timing of the period of development."

Interventions for infantile esotropia

BACKGROUND

Various aspects of the clinical management of infantile esotropia (IE) are unclear - mainly, the most effective type of intervention and the age at intervention.

OBJECTIVES

The objective of this review was to assess the effectiveness of various surgical and non-surgical interventions for IE and to determine the significance of age at treatment with respect to outcome.

SEARCH STRATEGY

Trials were identified from the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) in The Cochrane Library (Issue 3 2004), MEDLINE (1966 to July 2004), EMBASE (1980 to August 2004) and LILACS (July 2004). We manually searched the conference proceedings of the European Strabismological Association (ESA) (1975-1997, 1999-2002), International Strabismological Association (ISA) (1994) and American Academy of Paediatric Ophthalmology and Strabismus meeting (AAPOS) (1995-2003). Efforts were made to contact researchers who are active in the field for information about further published or unpublished studies.

SELECTION CRITERIA

Randomised trials comparing any surgical or non-surgical intervention for infantile esotropia.

DATA COLLECTION AND ANALYSIS

Each reviewer independently assessed study abstracts identified from the electronic and manual searches.

MAIN RESULTS

No studies were found that met our selection criteria and therefore none were included for analysis.

AUTHORS' CONCLUSIONS

The main body of literature on interventions for IE are either retrospective studies or prospective cohort studies. It has not been possible through this review to resolve the controversies regarding type of surgery, non-surgical intervention and age of intervention. There is clearly a need for good quality trials to be conducted in these areas to improve the evidence base for the management of IE.