Pediatric Eye Disease Investigator Group. Spontaneous resolution of early-onset esotropia: experience of the Congenital Esotropia Observational Study

The incidence, clinical features, and management of essential infantile esotropia in the United Kingdom. A British Ophthalmology Surveillance Unit (BOSU) study

BACKGROUND/OBJECTIVES

A national study was undertaken through the British ophthalmology surveillance unit (BOSU) to determine the incidence, presenting features and management of essential infantile esotropia (EIE) in the UK.

METHODS

Data from a prospective national observational study of newly diagnosed EIE presenting to clinicians in the United Kingdom over a 12-month period were collected. Cases with a confirmed diagnosis by a clinician of a constant, non-accommodative esotropia ≥20 prism dioptres (PD), presenting at ≤12 months, with no neurological or ocular abnormalities were identified through BOSU. Follow-up data were collected at 12 months.

RESULTS

A total of 57 cases were reported giving an incidence of EIE of 1 in 12,828 live births. The mean age of diagnosis and intervention were 7.05 ± 2.6 months (range 2-12) and 14.7 ± 4.9 months (range 6.5-28.1), respectively. Management was surgical in 59.6%, botulinum toxin alone in 22.8%, and 17.5% were observed. The preoperative angle of esotropia was smaller in the observation group (P = 0.04). The postoperative angle of esotropia was not statistically significant between botulinum toxin or surgery (P = 0.3), although the age of intervention was earlier in the botulinum group (P = 0.007). Early intervention (before 12 months of age) did not influence the post-intervention motor outcomes between 0 and 10 prism dioptres of esotropia (P = 0.78).

CONCLUSIONS

The incidence of EIE in the UK is considerably lower than reported in other population-based studies. The preferred method of treatment was surgical with earlier intervention in those treated with botulinum toxin. An early age of intervention (<12 months) did not influence motor outcomes.

Comitant strabismus etiology: extraocular muscle integrity and central nervous system involvement-a narrative review

Strabismus is not a condition in itself but the consequence of an underlying problem. Eye misalignment can be caused by disease, injury, and/or abnormalities in any of the structures and processes involved in visual perception and oculomotor control, from the extraocular muscles and their innervations to the oculomotor and visual processing areas in the brain. A small percentage of all strabismus cases are the consequence of well-described genetic syndromes, acquired insult, or disease affecting the extraocular muscles (EOMs) or their innervations. We will refer to them as strabismus of peripheral origin since their etiology lies in the peripheral nervous system. However, in most strabismus cases, that is comitant, non-restrictive, non-paralytic strabismus, the EOMs and their innervations function properly. These cases are not related to specific syndromes and their precise causes remain poorly understood. They are generally believed to be caused by deficits in the central neural pathways involved in visual perception and oculomotor control. Therefore, we will refer to them as central strabismus. The goal of this narrative review is to discuss the possible causes behind this particular type of eye misalignment and to raise awareness among eyecare professionals about the important role the central nervous system plays in strabismus etiology, and the subsequent implications regarding its treatment. A non-systematic search was conducted using PubMed, Medline, Cochrane, and Google Scholar databases with the keywords "origins," "causes," and "etiology" combined with "strabismus." A snowball approach was also used to find relevant references. In the following article, we will first describe EOM integrity in central strabismus; next, we will address numerous reasons that support the idea of central nervous system (CNS) involvement in the origin of the deviation, followed by listing several possible central causes of the ocular misalignment. Finally, we will discuss the implications CNS etiology has on strabismus treatment.

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.

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.

Bilateral combined resection-recession of the same rectus muscle versus Fadenoperation for treatment of purely tonic esotropias

PURPOSE

To compare the efficiency of bilateral combined resection-recession surgery of the medial rectus muscle versus using a modified Fadenoperation for surgical management of esotropias that totally resolve under general anesthesia, which we called "purely tonic" esotropias.

METHODS

We included 65 unselected consecutive cases of patients with purely tonic esotropias who underwent surgery between October 2017 and 2018. Patients were divided into group I, who underwent a combined resection and recession of medial recti muscles, and group II, who underwent a bilateral medial rectus Fadenoperation using posterior strapping. A satisfactory outcome was defined as deviation ⩽10 prism diopters (PD), at near and distance fixation, between 3 and 6 months postoperatively.

RESULTS

Mean initial deviation was in group I, 19.6 PD and 32.0 PD, in group II, 23.6 PD and 33.5 PD, at distance and near fixation respectively. Postoperatively, in group I, 31 patients (91.2%) showed satisfactory alignment at near and distance fixation. Post-operatively, in group II, 25 patients (80.6%) showed satisfactory alignment at near and distance fixation.

CONCLUSION

Our results suggest both techniques are good options to treat purely tonic esotropias.

Multiple Short Daily Periods of Normal Binocular Vision Preserve Stereopsis in Strabismus

Purpose

Infantile strabismus impedes the development of stereopsis. In optically strabismic monkeys, 2 continuous hours of normal binocular vision per day has been shown to preserve near-normal stereopsis. In this study, we investigated whether, as in learning, multiple shorter periods of intervention would further boost performance.

Methods

To simulate infantile esotropia, infant monkeys were reared with 30 prism diopters base-in starting at 4 weeks of age. Daily periods of normal binocular vision were provided by replacing prisms with plano lenses. Altogether, 14 monkeys were prism reared: 2 with continuous prism, 2 with 2 continuous hours of normal binocular vision per day, 6 with 2 noncontinuous hours, and 4 with 1 noncontinuous hour of binocular vision each day. Seven normally reared monkeys provided control data. Behavioral methods were employed to measure spatial contrast sensitivity, eye alignment, and stereopsis.

Results

One monkey reared with continuous prism had poor stereopsis, and the other had no stereopsis. Ten of the 12 monkeys reared with periods of normal binocular vision had stereopsis, and those with longer and more continuous periods of binocular vision had stereopsis approaching that of normally reared monkeys.

Conclusions

During early development, multiple short periods of binocular vision were effective in preserving clinically significant stereopsis in monkeys. These results suggest that by providing relatively short multiple daily intervention periods, stereopsis may be preserved in strabismic human children.

Clinical features of strabismus in patients with congenital optic disc anomaly

Purpose

To investigate the clinical features of strabismus in patients with congenital optic disc anomaly and compare and analyze the characteristics of patients who showed changes in the strabismus pattern with those who did not.

Methods

Medical records of the patients who were diagnosed with both strabismus and congenital optic disc anomaly and followed-up for ≥1 year were reviewed retrospectively. Clinical characteristics and ophthalmic features at the initial visit and final follow-up were assessed. Patients with a change in the direction of strabismus or a difference of >10 prism diopters in the deviation angle during the follow-up period were allocated to the changed group. The remaining patients were assigned to the unchanged group. The clinical characteristics of the two groups were compared.

Results

Twenty-eight patients (15 boys) were included (mean age, 39.0 months; range, 5–150 months). Three (10.7%) patients were born preterm and four (14.3%) had other underlying systemic disease. Sixteen (57.1%) patients had exotropia, and 12 (42.9%) had esotropia. Concurrent vertical strabismus was present in three (10.7%) patients. Strabismus features changed in 14 (50.0%, changed group) patients and remained unchanged in 14 (50.0%, unchanged group) patients. Age, sex, and laterality did not differ between groups. Preterm birth history (n = 3) and combined systemic disease (n = 4) were only observed in the changed group (p = 0.111 and p = 0.049, respectively).

Conclusions

Considering the possibility of changes in strabismic features, close monitoring of patients with strabismus combined with congenital disc anomaly is essential, particularly in those with preterm birth history or underlying systemic conditions.

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.

Long-Term Effects of Botulinum Toxin in Large-Angle Infantile Esotropia

Purpose

The purpose of this study is the motor outcome analysis of early Botulinum toxin (BT) treatment in patients affected by large-angle infantile esotropia (IE).

Patients and Methods

Retrospective analysis of 130 medical charts of IE patients who underwent BT injections between 2004 and 2019 was performed. All patients underwent BT injections within 13 months of age.

Results

Thirty patients, matching the inclusion criteria, were included in the study. Twenty-eight patients showing residual ET ≥25 PD (34.3±6.6 PD ranged from 25 to 50) underwent surgery.

Conclusion

Our result after 1 Botulinum toxin injection showed a very low success rate (6.7%) at last follow-up (28.3±7.2 months). Our data would suggest one Botulinum toxin injection in children affected by large-angle infantile esotropia allows a significant reduction of deviation but does not avoid the need for surgical treatment.

Relation between preoperative hyperopia and surgical outcome in infantile esotropia

AIM

To evaluate the relation between preoperative hyperopia and surgical outcomes of infantile esotropia in patients younger than 24 months of age.

METHODS

Medical records of patients who underwent bilateral medial rectus muscle recession for infantile esotropia between November 1, 2002 and December 1, 2011 were retrospectively reviewed. Patients were divided into two groups according to the degree of preoperative hyperopia. Group I had less than +3.0 diopter (D) of hyperopia and group II had between +3.0 and +5.0 D of hyperopia. Postoperative alignments were evaluated 1wk, 3, 6mo, and 1y after surgery. Following the 1-year postoperative visit, patients were monitored yearly. Relationships between preoperative factors including hyperopia and postoperative outcomes were evaluated.

RESULTS

Forty-six patients were included, with 33 patients in group I and 13 patients in group II. The preoperative mean refractive error was +0.88 D in group I and +3.45 D in group II. Surgical outcomes were not significantly different between groups at any postoperative time point examined. Cumulative probability of surgical success, prevalence of inferior oblique overaction, dissociated vertical deviation, and re-operation rate were not significantly different between groups.

CONCLUSION

Preoperative moderate hyperopia (less than +5.0 D) did not affect the surgical outcome of infantile esotropia. Therefore, the surgical correction of esotropia should be considered when the angle of esodeviation is unchanged following hyperopia correction, even in children with moderate hyperopia.

Universal ocular screening of 481 infants using wide-field digital imaging system

Background

Universal ocular screening of infants is not a standard procedure in children’s health care system in China. This pilot study investigated prevalence of ocular abnormalities of 6 weeks-age infants using wide-field digital imaging system.

Methods

Infants aged 6 weeks around were consecutively enrolled in a public hospital between April 2015 and August 2016. All the infants who were enrolled in the study underwent vision assessment, eye position examination, external eye check, pupillary light reflex, red reflex examination, anterior and posterior ocular segments were examined using flashlight, ophthalmoscope, and wide-field digital imaging system.

Results

A total of 481 infants at 45.1 ± 6.1 days after birth were enrolled in the study. 198 infants had abnormal findings (41.2%). Retinal white spots and retinal white areas were the most common findings (42.9% of abnormalities and 17.7% of all infants screened). The second major finding was retinal hemorrhage (16.2% of abnormalities and 6.7% of all infants screened). Other abnormal findings include retinal pigmentation, concomitant exotropia, neonatal dacryocystitis, retinopathy of prematurity, ‘albinism-like fundus’, congenital nasolacrimal duct obstruction, familial exudative vitreoretinopathy, immature retina, corneal dermoid tumor, large physiologic cupping of optic disc, congenital persistent pupillary membrane, entropion trichiasis, subconjunctival hemorrhage, congenital cataract, vitreous hemorrhage, ptosis and choroidal nevus. Intervention of any form was required in 22 infants, which accounted for 11.1% of abnormalities detected and 4.6% of all infants screened.

Conclusion

Universal ocular screening is not only necessary for preterm infants but also for full-term infants. Addition of red reflex examination with wide-field digital imaging system can enhance the sensitivity of screening for ocular fundus abnormities. Further study with a long-term follow-up is needed in the future.

Congenitally Impaired Disparity Vergence in Children With Infantile Esotropia

Purpose

We examined whether congenital impairment of disparity vergence in infantile esotropia (ET) exists in children with short duration ET (≤3 months) compared with long-duration ET and healthy controls. A short duration of misalignment would allow for a substantial amount of balanced binocular input during the critical period of binocular disparity development.

Methods

A total of 19 children aged 5 to 12 years and treated for infantile ET with a short (≤3 months; n = 10) or long (≥5 months; n = 9) duration of constant misalignment before alignment were enrolled. A total of 22 healthy control children were enrolled as a comparison group. Eye movements during disparity vergence and accommodative vergence were recorded using an EyeLink 1000 binocular eye tracker. Mean response gain was compared between and within groups to determine the effect of duration of misalignment and viewing condition.

Results

Compared with controls, children with short (P = 0.002) and long (P < 0.001) duration infantile ET had reduced response gains for disparity vergence, but not for accommodative vergence (P = 0.19).

Conclusions

Regardless of duration of misalignment, children with infantile ET had reduced disparity vergence, consistent with a congenital impairment of disparity vergence in infantile ET. Although early correction of misalignment increases the likelihood that some level of binocular disparity sensitivity will be present, normal levels may never be achieved.

To what Extent May Botulinum Toxin Type A Injections be an Alternative Choice to Surgery in Infantile Esotropia?

Introduction

Evaluation of a single injection of botulinum toxin A in infantile esotropia as an alternative choice to surgery in a retrospective cases serie.

Methods

Patients (65 consecutive children aged 9 to 26 months with infantile strabismus) underwent botulinum toxin A injection in both medial recti Botulinum toxin A injection. Clinical datas including measurement of angle of deviation before and after injection. visual acuity, stereoscopy and side effects were observed in a 24 months period of follow-up.

Results

Stable satisfactory result (angle equal to or less than 8 dioptres) was obtained in 33 cases (50.7%). Excellent result (-2 to + 4 dioptres) were obtained in 17 children (26%). Additional surgery was required in 32 cases for a residual (albeit smaller angle than the initial deviation) or recurrent deviation and/or DVD (49,2%).

Conclusions

Botulinum toxin A reduces the tonic spastic motor component of strabismus and, should additional surgery be required (49% in our series), allows the procedure to be carried out on a smaller angle. A reduction in the maximum angle of deviation is thus achieved sooner, and allows the development of anomalous binocularity in a stable microtropia.

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.

The prevalence of amblyogenic factors in children with persistent congenital nasolacrimal duct obstruction

BACKGROUND

To evaluate the prevalence of amblyopia risk factors in children that underwent probing for persistent congenital nasolacrimal duct obstruction (CNLDO).

METHODS

The medical records of children with CNLDO (after 1 year of age) that underwent probing were reviewed. Amblyopia risk factors, based on the American Association for Pediatric Ophthalmology and Strabismus referral criteria in 2013, were sought in the patientsʹ records before probing. The proportion of the patients with anisometropia >1.5 diopters (D) was separately calculated. In unilateral cases of CNLDO, sphere, astigmatism, and spherical equivalent of the eyes with CNLDO were compared with contralateral eyes in order to assess the effect of CNLDO on refractive error. In the follow-up examinations, the success of the probing or the need for additional procedures (Crawford intubation, Monoka intubation, or dacryocystorhinostomy) was evaluated. The prevalence of anisometropia between 'successful probing' and 'failed probing' groups was compared.

RESULTS

A total of 433 cases were included in the study. 41 cases (9.46 %) had amblyopia risk factors. Twenty-four cases (5.5 %) had anisometropia >1.5 D (spherical or cylindrical). In unilateral cases of CNLDO, the sphere and spherical equivalent of the eyes with CNLDO were significantly greater than those of the contralateral eyes (p < 0.001 for both). Thirty-nine patients (9 %) required other interventions due to failure of probing (failed probing group). There were significantly more anisometropia prevalence in this group, compared with the successful probing group, at the initial examination (p = 0.03).

CONCLUSIONS

The findings of greater prevalence of anisometropia >1.5 D (compared with the prevalence in the general population) and significantly greater sphere and spherical equivalents in the eye with CNLDO (compared with contralateral eye) in unilateral cases with CNLDO, suggested some relationships between anisometropia and long-term untreated CNLDO. The finding of more anisometropia in failed probing cases may support the theory of structural abnormality as an explanation for the possible relationship between congenital nasolacrimal duct obstruction and anisometropia.

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.

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

In the Early vs. Late Infantile Strabismus Surgery Study (ELISSS), 13.5% of children operated at 20 months vs. 3.9% of those operated at age 4 had gross binocular vision (Titmus Housefly). Reoperation rates were 28.7% in the former vs. 24.6% in the latter group and, although all were eligible for surgery at baseline at 11 SD 3.7 months, 8% in the early group vs. 20% in the late group were never operated, mostly because their angle decreased spontaneously. We assessed the predictive value of age, angle, and refraction in these matters.

METHODS

The ELISSS reoperation rates were first compared with those found in nine series of consecutive cases in nine university clinics operated during one particular year, between 6 and 23 years previously. Logistic regression was used to estimate the effect of postoperative angle and clinic on the chance of reoperation. Secondly, a meta-regression analysis was done of these and other reported reoperation rates. The mean age at operation and the mean duration of follow-up were regressed on the logistically transformed reported reoperation rates. Finally, to estimate the chance of spontaneous decrease of the angle without surgery, a random-effects model was fitted on the 6-monthly orthoptic measurements of angle and refraction in the ELISSS that antedated surgery, loss to follow-up, or final examination. In the random-effects model (see online-only supplement link or visit, www.simonsz.net), for ELISSS patients the random effect was defined as the deviation of the average angle, the fixed effect. A vector was defined based on age and spherical equivalent of the patient. The variance around the prediction consisted of uncertainty in the estimations, random effects, and residuals.

RESULTS

In the retrospective study, 204 patients who had been first operated between 6 and 23 years previously were eligible. A reoperation had been performed in 32 (19.3%) of the remaining 166 children who were 4.33 SD 1.35 years old at first surgery. The reoperation rate was 7.3% for those with a postoperative angle of -4° to +4° (N = 82), 25% for postoperative divergence > 5°, and 29% for postoperative convergence 10° to 14°. Strabismologists overestimated the reoperation rates at double. In the meta-regression analysis, 12 studies were included. Reoperation rates were between 60% and 80% for children first operated around age 1 and approximately 25% for children operated around age 4 (best fit: -0.221 Ln [age in months] + 1.1069; R(2) = 0.5725). Finally, in the predictions of random-effects model, a small angle at age 1 and hyperopia of approximately +4 increased the chance of spontaneous decrease of the angle into a microstrabismus.

DISCUSSION

The benefit of early surgery for gross binocular vision is balanced by a higher reoperation rate and an occasional child being operated that would have had a spontaneous decrease into a microstrabismus without surgery. The fact that, in the ELISSS, hyperopia was associated with a decrease of the angle underscores the benefit of early refractive correction.

Comparison of botulinum toxin with surgery as primary treatment for infantile esotropia

PURPOSE

To compare bilateral medial rectus muscle injection of botulinum toxin with surgery as primary treatment for infantile esotropia.

METHODS

A single-center, prospective, nonrandomized comparative study was undertaken of botulinum toxin versus surgery in children who presented by age 36 months with esotropia onset before 12 months. Successful outcome was defined as ocular alignment within 10Delta of orthotropia after one surgery or 1 to 3 bilateral botulinum injections.

RESULTS

Of 442 subjects, 322 received botulinum toxin (1 injection, 49%; 2, 41%; 3, 10%); 120 had surgery. Motor success was achieved in 66% of surgery patients, compared with 45% of botulinum patients (p < 0.001). Among subjects with deviation >30Delta, surgery achieved 69% success versus 36% with botulinum toxin (relative risk, 1.95; 95% CI, 1.53-2.49). At deviations < or = 30Delta, there was no difference (surgery, 60%; botulinum toxin, 59%; relative risk, 1.03; 95% CI, 0.78-1.35). There were no statistically significant differences in mean pretreatment deviation (botulinum toxin, 38.8Delta; surgery, 38.2Delta) or mean follow-up (botulinum toxin, 22.6 months; surgery, 20.7). Surgery occurred later than botulinum injection (mean age at treatment, 27.0 vs. 16.7 months; p < 0.001) with greater duration of misalignment (21.0 vs 12.5 months, respectively; p < 0.001), but neither variable influenced outcome in multivariate regression.

CONCLUSIONS

In this large, nonrandomized prospective cohort, surgery was more successful than botulinum toxin in the treatment of large-angle esotropia. Botulinum toxin appeared most effective for esotropia <30Delta to 35Delta, with a success rate comparable with surgery. Botulinum toxin may be an alternative to surgery in children with small- to moderate-angle infantile esotropia.

The relationship between preoperative alignment stability and postoperative motor outcomes in children with esotropia

PURPOSE

To examine the effect of preoperative alignment stability on postoperative motor outcomes in children who underwent surgery for esotropia.

METHODS

One hundred sixty-seven subjects (68 with infantile esotropia and 99 with acquired esotropia) aged less than 6 years had surgery after completing 18 weeks of follow-up as part of an observational study. Preoperative alignment was classified as stable, uncertain, or unstable, based on measurements taken at baseline and every 6 weeks for 18 weeks. Distance alignment measured by prism and alternate cover test was compared among stability classification groups at 6 weeks and 6 months after surgery.

RESULTS

Among subjects with infantile esotropia, median 6-week postoperative deviation was 2(Delta), 6(Delta), and 2(Delta) for subjects with stable, uncertain, and unstable preoperative alignment, respectively (p = 0.73 for stable vs unstable). Median 6-month postoperative deviation was 1(Delta), 9(Delta), and 1(Delta) for stable, uncertain, and unstable, respectively (p = 1.00 for stable vs unstable). Among subjects with acquired esotropia, median 6-week postoperative deviation was 6(Delta), 4(Delta), and 4(Delta) for subjects with stable, uncertain, and unstable preoperative alignment, respectively (p = 0.69 for stable vs unstable). Median 6-month postoperative deviation was 8(Delta), 4(Delta), and 6(Delta) for stable, uncertain, and unstable, respectively (p = 0.22 for stable vs unstable).

CONCLUSIONS

Postoperative alignment at 6 weeks and 6 months appears similar in children with stable versus unstable preoperative esotropia. Nevertheless, our finding should be interpreted with caution due to small sample size.

Stereoacuity outcomes after treatment of infantile and accommodative esotropia

PURPOSE

To review what is known about the normal maturation of stereoacuity, the stereoacuity deficits associated with infantile and accommodative esotropia, the rationale for making improved stereoacuity a goal of treatment, and strategies for improving stereoacuity outcomes.

METHODS

Studies of stereoacuity maturation during normal development, studies of stereoacuity outcomes after treatment for infantile and accommodative esotropia, and studies of primate models of esotropia are reviewed.

RESULTS

Stereoacuity maturation normally proceeds rapidly during the first year of life. Infantile and accommodative esotropia are associated with profound and permanent disruption of stereopsis. Although rehabilitation of stereoacuity after treatment of esotropia remains a challenge, even the achievement of subnormal stereoacuity may have real benefits to the child.

CONCLUSIONS

Some abnormalities in stereoacuity may exist before the onset of esotropia, but others may result directly from abnormal binocular experience. Several strategies for improving stereoacuity outcomes in esotropia are currently under active investigation. Improved stereoacuity outcomes are associated with better long-term stability of alignment, reduced risk for and severity of amblyopia, improved achievement of sensorimotor developmental milestones, better reading ability, and improved long-term quality of life.

Clinical trials - more than an assessment of treatment effect: LXV Edward Jackson Memorial Lecture

PURPOSE

To review the development of clinical trials and demonstrate their value beyond the assessment of the treatment effect.

DESIGN

Retrospective literature review.

METHODS

Retrospective literature review.

RESULTS

There has been a rapid increase in the number of clinical trials in ophthalmology as assessed by the number of ophthalmic publications and the number of ongoing National Eye Institute-(NEI) sponsored clinical trials over the last four decades. The public health significance of the results of these NEI clinical trials goes beyond the demonstration of treatment effects and side effects. From these trials, we learn about the clinical course and risk factors of disease, allowing us to better determine who and when to treat. Furthermore, the collaboration of investigators, as they develop and carry out protocols, facilitates incorporation of new ideas into the practice of medicine.

CONCLUSIONS

The practice of medicine is increasingly dependent on the results of carefully designed clinical trials. The determination as to whether a new treatment is safe and effective is important, but the additional information we can obtain regarding natural history, risk factors, and patient satisfaction adds immeasurably to our ability to care for our patients.

Timing of surgery for infantile esotropia: sensory and motor outcomes

Infantile esotropia is a common ophthalmic disorder in childhood. It is often accompanied by profound maldevelopment of stereopsis, motion processing, and eye movements, despite successful surgical realignment of the eyes. The proper timing of surgery has been debated for decades. There is growing evidence from clinical and animal studies that surgery during the early critical periods enhances sensory and ocular motor development. The Congenital Esotropia Observational Study has defined a clinical profile of infants who will benefit most from early surgery, and several other studies have shown that early surgery does not lead to adverse long-term effects. Clinicians now should consider offering early surgery to patients with large-angle, constant infantile esotropia at or before 10 months of age.

Instability of ocular alignment in childhood esotropia

OBJECTIVE

Instability of ocular alignment may cause surgeons to delay surgical correction of childhood esotropia. The authors investigated the stability of ocular alignment over 18 weeks in children with infantile esotropia (IET), acquired nonaccommodative esotropia (ANAET), or acquired partially accommodative esotropia (APAET).

DESIGN

Prospective, observational study.

PARTICIPANTS

Two hundred thirty-three children aged 2 months to less than 5 years with IET, ANAET, or APAET of less than 6 months' duration.

METHODS

Ocular alignment was measured at baseline and at 6-week intervals for 18 weeks.

MAIN OUTCOME MEASURES

Using definitions derived from a nested test-retest study and computer simulation modeling, ocular alignment was classified as unstable if there was a change of 15 prism diopters (PD) or more between any 2 of the 4 measurements, as stable if all 4 measurements were within 5 PD or less of one another, or as uncertain if neither criteria was met.

RESULTS

Of those who completed all 3 follow-up visits within time windows for analysis, 27 (46%) of 59 subjects with IET had ocular alignment classified as unstable (95% confidence interval [CI], 33%-59%), 20% as stable (95% CI, 11%-33%), and 34% as uncertain (95% CI, 22%-47%). Thirteen (22%) of 60 subjects with ANAET had ocular alignment classified as unstable (95% CI, 12%-34%), 37% as stable (95% CI, 25%-50%), and 42% as uncertain (95% CI, 29%-55%). Six (15%) of 41 subjects with APAET had ocular alignment classified as unstable (95% CI, 6%-29%), 39% as stable (95% CI, 24%-56%), and 46% as uncertain (95% CI, 31%-63%). For IET, subjects who were older at presentation were less likely to have unstable angles than subjects who were younger at presentation (risk ratio for unstable vs stable per additional month of age, 0.85; 99% CI, 0.74-0.99).

CONCLUSIONS

Ocular alignment instability is common in children with IET, ANAET, and APAET. The impact of this finding on the optimal timing for strabismus surgery in childhood esotropia awaits further study.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Timing of surgery for infantile esotropia in humans: effects on cortical motion visual evoked responses

PURPOSE

Infantile esotropia is associated with maldevelopment of cortical visual motion processing, manifested as directional asymmetry of motion visual evoked potentials (mVEPs). The purpose of this study was to determine whether early surgery at or before age 11 months could promote the development of cortical visual motion processing in human infants, compared with standard surgery at age 11 to 18 months.

METHODS

Sixteen children with a constant, infantile esotropia >or=30 prism diopters and onset before age 6 months were recruited prospectively. Eight of them underwent early surgery at

RESULTS

The mean asymmetry index and interocular phase difference in the early surgery group were comparable to that in age-matched control subjects, and they were significantly lower than those in the standard surgery group.

CONCLUSIONS

Early surgery for infantile esotropia promotes the development of cortical visual motion processing, whereas standard surgery is associated with abnormal mVEPs. The results provide additional evidence that early strabismus repair is beneficial for cortical development in human infants.

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Key Words Collapse

MESH Headings

• Evoked Potentials, Visual/physiology
• Eye Movements/physiology
• Female
• Humans
• Infant
• Male
• Motion Perception/physiology
• Nystagmus, Congenital/physiopathology
• Nystagmus, Congenital/surgery
• Oculomotor Muscles/surgery
• Prospective Studies
• Tendons/surgery
• Time Factors
• Visual Cortex/physiology

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Grants

• 67104 CIHR

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Affiliation(s)

Christina Gerth Department of Ophthalmology and Vision Science, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada
Giuseppe Mirabella
Xiaoqing Li
Thomas Wright
Carol Westall
Linda Colpa
Agnes M F Wong

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Effect of preoperative stability of alignment on outcome of strabismus surgery for infantile esotropia

INTRODUCTION

Some strabismus surgeons wait until the angle of deviation stabilizes prior to operating on patients with infantile esotropia. This study evaluated whether a preoperative increase in the angle of deviation affected surgical outcomes.

METHODS

This was a retrospective comparative case series in which records of patients with infantile esotropia, who had surgery performed before age 2 years and who were followed for at least 2 years postoperatively, were reviewed to identify two groups for comparison: the first had </=5(Delta) change in the angle of deviation between the first office visit and time of surgery; the second had a >/=10(Delta) increase in the angle of deviation prior to surgery. In the latter group, surgery was performed for the angle present at the time of surgery. Outcomes were considered successful if the patients had microtropias.

RESULTS

Fifteen patients were identified in each group. The interval between the first office visit and time of surgery was the same in both groups (mean, 2 months). Outcomes were successful in 11 of 15 (73%) in each group (no significant difference, p = 0.659).

CONCLUSIONS

There was no difference in outcome between children whose angles of deviation were stable and those whose angles increased prior to surgery. This indicates that strabismus surgery does not need to be delayed while waiting for the angle of deviation to stabilize. Surgical correction may therefore be achieved at an earlier age, which may have a beneficial effect on outcome.

Variables associated with the incidence of infantile esotropia

PURPOSE

Infantile esotropia (manifesting from birth to 6 months) is a common type of strabismus, accounting for 28% to 54% of all esotropias and with an incidence of 1% of the general population. The purpose of this cohort study was to evaluate risk factors for infantile esotropia. Such information may aid in early intervention to prevent manifestation of infantile esotropia.

METHODS

A retrospective chart review of 5,347 records (October 1, 1993, to September 30, 2003) of birth mothers and infants at the W.W. Hastings Indian Health Science Hospital in Tahlequah, Oklahoma, was performed to identify children with varying degrees of Native American blood who had infantile esotropia. A nonstrabismic birth cohort control group was also identified. Twenty-three medical records indicating a diagnosis of infantile esotropia that were complete enough to be used in analysis were identified. Normal infants were compared with infants with esotropia.

RESULTS

Infantile esotropia in this preliminary study was associated with 24 factors including prematurity, family ocular history, cardiovascular disease, systemic disease, pregnancy-associated hypertension and low birth weight (<2,500 g) among others.

CONCLUSIONS

Prematurity, family history or secondary ocular history, perinatal or gestational complications, systemic disorders, use of supplemental oxygen as a neonate, use of systemic medications, and male sex were found to be significant risk factors for infantile esotropia. Our results provide additional evidence that might help facilitate early detection and intervention in cases in which these risk factors are identified.

Long-term motor and sensory outcomes after early surgery for infantile esotropia

PURPOSE

The proper timing of surgery for infantile esotropia remains controversial. Early surgery may yield better sensory outcomes whereas later surgery may result in better alignment. Several recent studies reported promising sensory outcomes in small groups of children that underwent surgery by 6 months of age. Here, we present motor and sensory outcomes of a cohort of 50 consecutive children enrolled in a prospective study who had surgery by 6 months of age and were followed for 4-17 years.

METHODS

Angle of deviation, subsequent surgeries, treatment with spectacles, amblyopia, fusion, and stereopsis were evaluated during follow-up. Outcomes from the early surgery group were compared with a concurrently recruited cohort who had surgery at 7-12 months (n=78).

RESULTS

On the initial visit, both cohorts had the same median angle of deviation (45(Delta)) and similar refractive error; the median angle of deviation increased by the final preop visit (55(Delta)). Postoperatively, both cohorts had alignment within 6(Delta) in 83-94% of cases on all visits. Both cohorts had similar rates of additional surgery, and 44-48% wore hyperopic correction postoperatively. Compared with the 7- to 12-month cohort, more children in the early-surgery cohort had peripheral fusion (78% vs 61%; p < 0.02), central fusion (15% vs 2%; p < 0.01), Randot stereopsis (38% vs 16%; p < 0.003), and Randot stereoacuity of 200 seconds or better (20% vs 9%; p < 0.05).

CONCLUSIONS

Early surgery was associated with a higher prevalence of fusion and stereopsis, without adverse motor outcomes.

The course of intermittent exotropia in a population-based cohort

PURPOSE

To evaluate the change in the angle of deviation in an incidence cohort of pediatric patients diagnosed with intermittent exotropia during a 20-year period.

DESIGN

Retrospective, population-based observational study.

PARTICIPANTS

All pediatric (<19 years old) residents of Olmsted County, Minnesota diagnosed with intermittent exotropia (> or =10 prism diopters) from January 1, 1975 through December 31, 1994.

METHODS

The medical records of all potential patients identified by the resources of the Rochester Epidemiology Project were reviewed.

MAIN OUTCOME MEASURES

The change in the angle of deviation and its association with treatment were reviewed for each patient.

RESULTS

A total of 184 pediatric patients were diagnosed during the study period, of which 138 patients (75.0%) had > or =2 examinations. The deviation resolved in 5 of the 138 patients (3.6%) during a median follow-up of 9.2 years, while the Kaplan-Meier rate of increasing by 10 or more prism diopters (PD) was 23.1% at 5 years and 52.8% at 20 years. The distance deviation increased by a median of 5 PD during the preoperative period in the 55 patients who underwent surgery during a mean follow-up of 3.2 years compared with a zero PD median change in the 83 patients who avoided surgery during a mean follow-up of 7.1 years. The Kaplan-Meier probability of undergoing surgery within 20 years after diagnosis was 74.0% in this population. We were unable to detect a significant association between nonsurgical treatments and a change in the angle of deviation.

CONCLUSIONS

In this population-based cohort of pediatric patients with intermittent exotropia, the deviation resolved in 4%, and more than half of the patients were expected to have an increase of 10 or more PD within 20 years of their diagnosis. Children who received surgery in this population were significantly more likely to have demonstrated an increase in their deviation during the preoperative period.

Final report of the early vs. late infantile strabismus surgery study (ELISSS), a controlled, prospective, multicenter study

BACKGROUND

The optimal age for surgery for infantile esotropia is controversial. Proponents of early surgery believe that further loss of binocular vision can be prevented by early surgery, a minority believes that binocular vision can even be restored by early surgery. The ELISSS compared early with late surgery in a prospective, controlled, non-randomized, multicenter trial.

METHODS

Fifty-eight clinics recruited children aged 6-18 months for the study. Each clinic operated all eligible children either 'early', i.e. at age 6-24 months, or 'late', i.e. at age 32-60 months. At baseline the angle of strabismus, refraction, degree of amblyopia and limitation of abduction were assessed. Intermediate examinations took place every six months. Children were evaluated at age six in the presence of independent observers. Primary endpoints were (i) level of binocular vision, (ii) manifest angle of strabismus at distance and (iii) remaining amblyopia. Secondary endpoints were number of operations, vertical strabismus, angle at near and the influence of surgical technique.

RESULTS

A total of 231 children were recruited for early and 301 for late surgery. Age at entry examination was 11.1 months (SD 3.7 months) in the early group and 10.9 (SD 3.7) months in the late group. Refraction, amblyopia and limitation of abduction were distributed equally in the early and late groups, but the angle of strabismus was slightly larger in the early group. Dropout-rates were 26.0% in the early and 22.3% in the late group. At age six, 13.5% of the early vs. 3.9% of the late group recognized the Titmus Housefly; 3.0% of the early and 3.9% of the late group had stereopsis beyond Titmus Housefly. No significant difference was found for angle of strabismus. 35.1% of the early group and 34.8% of the late group did not have an angle between 0 degrees and 10 degrees , the thresholds set for re-operation. For ratio of the visual acuities (remaining amblyopia) there was a small but significant advantage for the early group. There was hardly any correlation between the baseline parameters and the primary endpoints. Children scheduled for early surgery had first been operated at 20 (SD 8.4) months, but 8.2% had not been operated at age six. Children scheduled for late surgery had been operated at 49.1 (SD 12.7) months, but 20.1% had not been operated at age six. The number of operations per child was 1.18 (SD 0.67) in the early and 0.99 (SD 0.64) in the late group. Age at recruitment, age that strabismus reportedly had started and refraction at entry examination were similar among operated and non-operated children. Only the angle of strabismus at entry predicted, to some extent, whether a child had been operated at age six.

DISCUSSION

Children operated early had better gross stereopsis at age six as compared to children operated late. They had been operated more frequently, however, and a substantial number of children in both groups had not been operated at all.

Decision analysis with Markov processes supports early surgery for large-angle infantile esotropia

PURPOSE

To assess tradeoffs in time spent with aligned visual axes or stereopsis and risked reoperations between three strategies for the treatment of large-angle infantile esotropia: first surgery at 6, 24, or 48 months of age.

DESIGN

Decision analysis.

METHODS

We simulated three hypothetic cohorts of children with this condition until their eighth year. Potential achievement of stereopsis, the diagnosis of dissociated vertical divergence or inferior oblique overaction, and various complications were modeled. Probability estimates were obtained from a comprehensive literature review. Analyses aimed to determine the strategy that was associated with longer time spent with aligned eyes and/or stereopsis and fewer reoperations.

RESULTS

Eight-year-old children are expected to spend 72.6 vs 58.0 vs 37.8 months with aligned eyes and 26.8 vs 9.0 vs 1.5 months with stereopsis and to receive on average 1.76 vs 1.67 vs 1.46 surgeries, if they first underwent operation at 6 vs 24 vs 48 months, respectively. Children at 8 years are expected to have stereopsis at the rate of 36.1% vs 17.2% vs 5.1%, respectively. Operation at 6 months instead of 48 months is expected to yield an additional 9% of total follow-up time in health states with eye alignment and 11% in health states with stereopsis, per 5% increase in risk for extra operations (5% and 7%, respectively, per 5% increase in risk for operation at 6 vs 24 months). Wide-range sensitivity analyses and long-term projections point to the same direction.

CONCLUSION

Given the benefit/risk tradeoffs, it is probably warranted to attempt to correct large-angle infantile esotropia as early as possible.

Amblyopia characterization, treatment, and prophylaxis

Amblyopia has a 1.6-3.6% prevalence, higher in the medically underserved. It is more complex than simply visual acuity loss and the better eye has sub-clinical deficits. Functional limitations appear more extensive and loss of vision in the better eye of amblyopes more prevalent than previously thought. Amblyopia screening and treatment are efficacious, but cost-effectiveness concerns remain. Refractive correction alone may successfully treat anisometropic amblyopia and it, minimal occlusion, and/or catecholamine treatment can provide initial vision improvement that may improve compliance with subsequent long-duration treatment. Atropine penalization appears as effective as occlusion for moderate amblyopia, with limited-day penalization as effective as full-time. Cytidin-5'-diphosphocholine may hold promise as a medical treatment. Interpretation of much of the amblyopia literature is made difficult by: inaccurate visual acuity measurement at initial visit, lack of adequate refractive correction prior to and during treatment, and lack of long-term follow-up results. Successful treatment can be achieved in at most 63-83% of patients. Treatment outcome is a function of initial visual acuity and type of amblyopia, and a reciprocal product of treatment efficacy, duration, and compliance. Age at treatment onset is not predictive of outcome in many studies but detection under versus over 2-3 years of age may be. Multiple screenings prior to that age, and prompt treatment, reduce prevalence. Would a single early cycloplegic photoscreening be as, or more, successful at detection or prediction than the multiple screenings, and more cost-effective? Penalization and occlusion have minimal incidence of reverse amblyopia and/or side-effects, no significant influence on emmetropization, and no consistent effect on sign or size of post-treatment changes in strabismic deviation. There may be a physiologic basis for better age-indifferent outcome than tapped by current treatment methodologies. Infant refractive correction substantially reduces accommodative esotropia and amblyopia incidence without interference with emmetropization. Compensatory prism, alone or post-operatively, and/or minus lens treatment, and/or wide-field fusional amplitude training, may reduce risk of early onset esotropia. Multivariate screening using continuous-scale measurements may be more effective than traditional single-test dichotomous pass/fail measures. Pigmentation may be one parameter because Caucasians are at higher risk for esotropia than non-whites.

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.

Pre-operative stability of infantile esotropia and post-operative outcome

PURPOSE

To define the prevalence and time course of significant changes in angle of deviation during the first months after the diagnosis of infantile esotropia and to determine whether long-term alignment and sensory outcomes differ when surgical alignment is performed on infants with stable vs unstable angles of deviation.

DESIGN

Prospective cohort study.

METHODS

setting: Institutional and clinical practice. patient population: Newly diagnosed patients with infantile esotropia (N = 208). observation procedure: Preoperative measurements of the angle of deviation on the initial visit and at approximate six-week intervals until surgery was performed. main outcome measures: Ocular alignment at six weeks, one year, and four years postoperative and stereoacuity at age five to nine years.

RESULTS

Overall, 57% of infants had an esodeviation on the second visit that was within 10 prism diopters (p.d.) of the deviation measured on the initial visit (stable group), 33% had an increase of 10 p.d. or more (unstable group), and 11% had a decrease of 10 p.d. or more. Among the 127 patients with additional preoperative visits, many switched between the stable and unstable categories during follow-up. Long-term, stable and unstable preoperative alignment groups had similar postoperative motor alignment, re-operation rates, rates of prescription of hyperopic, or bifocal spectacle correction and stereoacuity.

CONCLUSIONS

It may not be necessary to wait for a "stable" angle of esodeviation before surgery since both alignment and sensory outcomes were similar for stable and unstable groups.

Childhood esotropia

PURPOSE

To review the most recent studies on childhood esotropia, and to summarize recent changes in treatment approach.

RECENT FINDINGS

Constant, large-angle esotropia present in the first few months of life may be suitable for early surgery. Earlier surgical intervention, within the first several months of onset, is associated with better sensory outcomes. Similar findings are true for accommodative esotropia; children treated within the first 4 months of constant esotropia have better outcomes. Refractive surgery has been used successfully in adult patients to treat accommodative esotropia.

SUMMARY

New developments pertaining to infantile esotropia have helped clarify the pathophysiology of the condition and the best treatment approaches. Abnormal binocular visual input early in life contributes to poor outcomes in both infantile and accommodative esotropia.

Progressive increase in the angle of deviation in acquired nonaccommodative esotropia of childhood

PURPOSE

Although the angle of deviation in patients with congenital esotropia has been shown to increase during the early preoperative period, few data exist regarding this change in other forms of childhood esotropia. The primary objective of this study was to investigate whether the angle of deviation increases with time in patients with acquired nonaccommodative esotropia (ANAET).

METHODS

The medical records of all children whose ANAET was diagnosed at East Tennessee State University College of Medicine from August 1, 1995, through October 1, 2001, were retrospectively reviewed. All patients were assessed for any change in the amount of their strabismic angle and associated risk factors.

RESULTS

Eighty-two patients with ANAET were identified, and all except 3 underwent more than one examination. Of the 79 children who underwent more than one examination, 26 (32.9%) displayed an angle increase of > or =10 prism diopters (PD) during a median follow-up period of 2.9 months. The ANAET of those patients whose angle increased by > or =10 PD was diagnosed (28.4 months of age vs 45.5 months of age, P =.003), and they underwent surgery (35.9 months of age vs 53.3 months of age, P =.003) at a significantly younger median age than those whose angle increased <10 PD.

CONCLUSIONS

The angle of deviation of approximately one third of patients with ANAET in this study increased at least 10 PD in the early preoperative period. This increase occurs more often in younger patients and underscores the importance of performing serial measurements of the deviating angle before surgical intervention is undertaken.

Too much or too little: neonatal ocular misalignment frequency can predict later abnormality

BACKGROUND

214 orthoptists' infants have been followed for up to 15 years, relating neonatal misalignment (NMs) and first convergence onset to later childhood ocular abnormalities. NMs are shown in a companion paper to reflect the onset of first convergence, but if frequent or absent may predict a higher risk of refractive error and esodeviation.

METHODS

In a prospective postal survey, orthoptist mothers observed their own infants during the first months of life and regularly reported ocular behaviour and alignment, visual development, and any subsequent ocular abnormalities.

RESULTS

Later strabismus and refractive error were less common in infants who showed NMs occasionally compared with those who never or frequently did. There was a significant linear trend for fewer ocular abnormalities to be found in children with more frequent NMs (p<0.001). Hypermetropes were later to show first convergence than emmetropes or myopes (p = 0.006)

CONCLUSIONS

NMs usually reflect an emerging and normally developing vergence system. This study suggests that delayed onset of convergence (and lack of NMs) is associated with later defects, especially hyperopia. Possible causal relations are discussed.

Neonatal ocular misalignments reflect vergence development but rarely become esotropia

BACKGROUND

214 orthoptists' infants have been followed for up to 15 years, relating neonatal misalignment (NMs) behaviour to onset of convergence and 20 Delta base out prism response, and also to later childhood ocular abnormalities.

METHODS

In a prospective postal survey, orthoptist mothers observed their own infants during the first months of life and regularly reported ocular behaviour and alignment, visual development, and any subsequent ocular abnormalities.

RESULTS

Results confirm previously reported characteristics of NMs. Infants who were misaligned more frequently were misaligned for longer periods (p <0.01) and were later to achieve constant alignment (p <0.001) but were earlier to attempt first convergence (p = 0.03). Maximum NM frequency was usually found at or before the onset of first convergence (p = 0.0002).

CONCLUSIONS

NMs occur in the first 2 months of life and usually reflect a normally developing vergence system. They appear to represent early attempts at convergence to near targets. Emerging infantile esotropia is indistinguishable from frequent NMs before 2 months.

Early versus delayed repair of infantile strabismus in macaque monkeys: I. ocular motor effects

INTRODUCTION

The appropriate age for surgical correction of esotropic strabismus in human infants is controversial; some clinicians advocate surgery before age 6 months, and others recommend observation and surgery at older ages. Infantile (congenital) esotropia in humans and monkeys is known to be accompanied by a constellation of eye movement abnormalities caused by maldevelopment of cerebral visual motor pathways. The purpose of this study was to determine how early versus delayed correction of strabismus influences development and/or maldevelopment of these eye movement pathways.

METHODS

Optical strabismus was created in infant macaques by fitting them with prism goggles on day 1 of life. The early correction group (2 experimental and 1 control) wore the goggles for a period of 3 weeks (the equivalent of 3 months before surgical repair in humans). The delayed correction group (3 experimental and 1 control) wore the goggles for a period of 3 or 6 months (the equivalent of 12 or 24 months before surgical repair in humans). Several months after the goggles were removed, the monkeys were trained to perform visual fixation, smooth pursuit, and optokinetic nystagmus (OKN) tasks for a juice reward. Eye movements were recorded using binocular search coils. The performance of the early versus delayed infant monkey groups was also compared with that of a group of adult monkeys who had unrepaired, naturally occurring infantile esotropia.

RESULTS

Early correction monkeys developed normal eye movements and exhibited ocular motor behaviors that were indistinguishable from normal control animals. They regained normal binocular eye alignment and showed stable fixation (no latent nystagmus). Monocular horizontal smooth pursuit and large field OKN were symmetric. In contrast, delayed correction monkeys showed persistent esotropia, latent fixation nystagmus, dissociated vertical deviation, and pursuit/OKN asymmetry. Animals who had the longest delay in correction of the optical strabismus exhibited eye movement abnormalities as severe as those of adult animals with uncorrected, natural esotropia.

CONCLUSIONS

Early correction of strabismus in primates prevents maldevelopment of eye movements driven by cerebral motor pathways. Our results provide additional evidence that early strabismus correction may be beneficial for brain development in human infants.

Clinical research in pediatric ophthalmology: the Pediatric Eye Disease Investigator Group

The Pediatric Eye Disease Investigator Group (PEDIG) is a network of university-based and community-based pediatric eye care practitioners that is conducting multiple clinical research studies. The group has conducted the Congenital Esotropia Observational Study, which assessed the early course of esotropia in infants, and the Amblyopia Treatment Studies, a series of randomized trials, the first of which compared atropine and patching for treatment of moderate amblyopia in children 3 to <7 years old. Herein, the results of these studies are summarized, and the current and future studies of the group are described.