Nonsurgical Consecutive Exotropia Following Childhood Esotropia: A Multicentered Study.

PURPOSE: Nonsurgical consecutive exotropia (NCX) occurs when an esotropia (ET) spontaneously converts to exotropia (XT) without surgical intervention. Although NCX is considered to occur in early-onset accommodative ET with high hyperopia, consensus on causation is lacking. We report the clinical characteristics of NCX and assess the response to conservative management. DESIGN: Retrospective, multicenter, observational case series. METHODS: Patients aged 6 months and older with an initial diagnosis of ET who converted to XT without surgical intervention. Sensory strabismus was excluded. Age, visual acuity, cycloplegic refraction, glasses prescriptions, deviation, and binocular vision were collected. RESULTS: Forty-nine children were included with a mean age of 3.5 ± 1.6 years and 8.4 ± 3.6 years at the time of ET and NCX, respectively. Mean refractive error was +4.40 ± 2.13 diopters (D) and +4.05 ± 2.74 D at the time of ET and NCX, respectively. Accommodative ET occurred in 60% of cases, and only 35.7% were high hyperopes. All but 1 patient presented with XT at distance. In response to the XT, a mean decrease in hyperopic prescription of 1.55 ± 0.48 D was given (N = 17); only 1 case reverted to ET. Eventually, 43% underwent XT surgery, with similar rates between those who had refractive management and those who did not. CONCLUSIONS: NCX occurs in both accommodative and nonaccommodative ET; high hyperopia is present in only one-third of cases. On average, drift to XT occurs within 5 years. Refractive management has a modest result. No predictive risk factors were identified. Our findings challenge hyperopia-linked theories of causation. Nonrefractive explanations, such as the role of the vergence system, deserve further study.

Factors associated with the effectiveness of part-time patching for intermittent exotropia in children.

PURPOSE: To evaluate the factors associated with the efficacy of low-dose part-time patching in children with intermittent exotropia (IXT). METHODS: In this prospective observational study, we enrolled 186 patients diagnosed with IXT. Outcome measures included office based control scales, magnitude of exo-deviation, and stereoacuity at near and distance after daily patching for 2 h. We analyzed the clinical data and demographic factors association with improvement of IXT. RESULTS: The study was completed by 152 subjects of total enrolled patients on a consecutive basis followed up for 1 year. Decrease in the magnitude of exo-deviation, improvement of control, and or gain of stereoacuity were observed in 31.6% patients of the recruited subjects after part-time patching. Multivariate analyses showed that prognostic factors determining improvement to part-time patching included convergence insufficiency (CI) type IXT (p = 0.016), poor distance stereopsis (p = 0.044), and large exotropic deviation at distance (p = 0.025). CONCLUSIONS: CI-type exotropia, large distance magnitude of exo-deviation, or poor distance stereopsis appear to be associated with a better response to part-time patching. Therefore low dose part-time patching may be a useful non-surgical treatment alternative to delay surgery in these cases.

[Neglected childhood strabismus: Epidemiological, clinical and therapeutic aspects]. / Strabisme de l'enfance négligé : aspects épidémiologiques, cliniques et thérapeutiques.

INTRODUCTION: In an environment where strabismus is poorly understood and management centers rare, we studied the epidemiological, clinical and therapeutic aspects of neglected childhood strabismus. MATERIALS AND METHODS: This was a retrospective study carried out from March 1st, 2013 to September 30, 2018. Neglected childhood strabismus was defined as strabismus occurring in the first 5 years of life, for which the patient was over 7-years-old at the time of first consultation. The variables studied were age at first consultation, gender, age of onset, type of strabismus, etiology of strabismus, angle of deviation and rate of surgery. RESULTS: We found 113 cases of neglected childhood strabismus among the 430 cases of strabismus seen during the study period. There were more females (n=64) than males. The mean age was 17.7±10.5 years. There were 73 exotropias (64.6 %). The mean angle of deviation was 41.2±12.2PD. Strabismus was early in 70.8 % of cases. Innervational strabismus accounted for 86.7 % of cases. The most frequent refractive error was hyperopic astigmatism (55.3 %). Of the 45 patients who were seen again after full-time wear of their full cycloplegic correction, 2 were orthotropic. Surgery was performed in 60.5 % of cases. The average postoperative angle of deviation was 6.6±9.4PD. CONCLUSION: Management of neglected childhood strabismus provides good results and should therefore be encouraged in order to improve the quality of life of affected patients.

Comparison of surgery versus observation for small angle intermittent exotropia.

In young children with small angle exotropia, making decisions for the individual patient whether to perform surgery or not, and choosing the optimal time for surgical intervention are quite difficult. We aimed to compare the long-term outcomes of small angle intermittent exotropia of 20 prism diopters (PD) or less after observation versus strabismus surgery. A retrospective study was performed on 164 patients aged 3 to 13 who underwent surgical intervention or observation with or without conservative management for intermittent exotropia of 14 to 20 PD. The minimum follow-up period was 2 years. The average follow-up period was 3.9 ± 2.2 years in the observation group and 4.5 ± 2.3 years in the surgery group. At the final examination, the mean angle of deviation at distance was 11.1 ± 8.9 PD in the observation group and 9.0 ± 7.5 PD in the surgery group, which was not significantly different (P = 0.121). Changes in sensory outcome and fusional control were not significantly different between both groups (P = 0.748 and P = 0.968). Subgroup analysis including patients with poor fusional control also showed similar results. By multivariate analysis, the type of surgery, unilateral recess-resect procedure, was the only predictive factor of good motor outcome in the surgery group. In conclusion, long-term surgical outcomes in small angle exotropia did not appear to be more satisfying than observation in terms of motor and sensory outcomes.

The effect of alternate occlusion on control of intermittent exotropia in children.

PURPOSE: The aim is to investigate the effect of alternate occlusion on control of intermittent exotropia in children 3 to 8 years old. METHODS: The ability of 28 children to control of the deviation at far and near was evaluated based on 3-point and 6-point control scales. Stereopsis and fusion were assessed using the Titmus and Worth 4-dot tests, respectively. Two-hour alternate daily occlusion was prescribed for children with no dominancy. For children with a dominant eye, 2-h occlusion of the dominant eye for 5 days and the non-dominant eye for 2 days. All measurements were repeated at 3, 6, and 9 months after the treatment. RESULTS: For all children with a mean age of 4.7 ± 1.56 years, deviation control at far improved significantly after 3, 6, and 9 months of treatment using both control scales when compared with baseline (p = 0.005 after 3 months and p = 0.008 after 6 and 9 months for the 3-point scale, and p < 0.001 after 3 and 6 months and p = 0.010 after 9 months for the 6-point scale). Control at near showed a significant improvement after 3, 6, and 9 months of treatment based on the 6-point scale (p = 0.007 for 3 months, p = 0.004 for 6 months, and p = 0.014 for 9 months). Near stereopsis improved significantly after 9 months of treatment (p = 0.043). CONCLUSION: Alternate occlusion is significantly effective on control of intermittent exotropia. As a result, it can be used as a useful method to postpone or even eliminate the need for surgery in intermittent exotropia.

Using Botulinum Toxin A as an Adjunct in the Surgery of Large-Angle Sensory Exotropia and Abducens Nerve Palsy.

Regarding the review article by Escuder AG, Hunter DG, entitled "The Role of Botulinum Toxin in the Treatment of Strabismus" Seminars in Ophthalmology. 2019;34(4): 198-204, we cannot agree with you more with your point of view about the dosage preparation for botulinum toxin A (BTA) in the strabismus surgery. Moreover, we also included a case series that used BTA as an adjunct in the surgery for large-angle sensory exotropia and abducens nerve palsy.

Conservative management of intermittent exotropia to defer or avoid surgery.

BACKGROUND: Surgery for intermittent exotropia performed at a very young age has poorer sensory outcomes than surgery performed later; moreover, postoperative recurrence is common, regardless of age. Alternate occlusion decreases the size of the exotropia and improves control. The purpose of this study was to report the long-term effects of part-time alternate occlusion and overminus spectacles combined with prism on delaying or avoiding surgery in intermittent exotropia. METHODS: The study included consecutive patients from 1979 to 2010 who had poorly controlled intermittent exotropia and were treated with alternate occlusion, followed in some cases by overminus spectacles with base-in prism. Outcome measures were initial improvement and subsequent time to surgery, if required. RESULTS: A total of 279 patients had initial control poor enough to otherwise be considered candidates for surgery. After occlusion therapy, 219 (78%) improved their angle and control, and 62 (22%) converted to an exophoria. After 1 year, 9 cases deteriorated, and surgery was recommended. In 207 (74%), conservative treatment delayed surgery for at least 1 year. At 20 years, 42 of 279 patients were still being followed. Of these, 22 of 219 (7%) were known to have not undergone surgery, and 127 (45%) had undergone surgery; 130 (47%) were lost to follow-up. CONCLUSIONS: Part-time alternate occlusion and overminus spectacles with prism can defer the need for surgery in a large percentage of patients with intermittent exotropia; for a small number it may be curative.

[Intermittent exotropia]. / Les strabismes divergents intermittents.

Intermittent exotropia (IXT) is the most common type of divergent strabismus. It is the consequence of passive mechanisms due to the anatomy of the globes and orbits or due to active innervational mechanisms, resulting in divergence of the visual axes, which is compensated by fusional convergence. Intermittent insufficiency in this compensation gives this form of exotropia its intermittent nature. The most common symptoms of IXT are closure of one eye, asthenopia and diplopia, but they are often absent. The clinical classification of IXT (according to Burian) is based on the difference between the distant and the near angles of deviation. It defines 4 types: true divergence excess (at distance), pseudo-divergence excess, the basic form (distance and near angles are equal) and convergence insufficiency (near angle greater than distance angle). One of the main difficulties in examination of IXT is neutralizing the fusional convergence in order to classify the strabismus. For this purpose, the monocular occlusion test, a near addition, or a prism adaptation test can be used. IXT is also characterised by the quality of control of the deviation by the patient, which is taken in account for therapeutic decision. Tools for measurement of this control have recently been developed and are not commonly used. The natural history of IXT is not well understood. Treatment relies mainly on optical correction, binocular visual training therapy and surgery, but their indications are not well defined, nor are outcomes analysis criteria. In the case of surgery, it aims to treat the maximum measured distance angle; the medium- and long-term angular results of surgery are often disappointing, although it probably improves control of the strabismus in most cases.

Three-Year Observation of Children 3 to 10 Years of Age with Untreated Intermittent Exotropia.

PURPOSE: To describe the course of intermittent exotropia (IXT) in children followed up without treatment for 3 years. DESIGN: Observation arm from randomized trial of short-term occlusion versus observation. PARTICIPANTS: One hundred eighty-three children 3 to 10 years of age with previously untreated IXT and 400 seconds of arc (arcsec) or better near stereoacuity. METHODS: Participants were to receive no treatment unless deterioration criteria were met at a follow-up visit occurring at 3 months, 6 months, or 6-month intervals thereafter for 3 years. MAIN OUTCOME MEASURES: The primary outcome was deterioration by 3 years, defined as meeting motor criterion (constant exotropia ≥10 prism diopters [Δ] at distance and near) or near stereoacuity criterion (≥2-octave decrease from best previous measure). For the primary analysis, participants also were considered to have deteriorated if treatment was prescribed without meeting either deterioration criterion. RESULTS: The cumulative probability of protocol-specified deterioration by 3 years was 15% (95% confidence interval, 10%-22%), but that was likely an overestimate, partly because of misclassification. Among 25 deteriorations, 2 met motor deterioration, 11 met stereoacuity deterioration, and 12 started treatment without meeting either criteria (7 for social concern, 1 for diplopia, 4 for other reasons). Among the 132 participants who completed the 3-year visit and had not been treated during the study, only 1 (<1%) met motor or stereoacuity deterioration criteria at 3 years. Of the 4 participants completing the 3-year visit who met deterioration criteria previously and had not started treatment, none still met deterioration criteria. Between the baseline and 3-year examination for these 132 patients, improvement occurred in distance and near stereoacuity (mean improvement, 0.14 and 0.14 logarithm of arcsec; P ≤ 0.001 and P ≤ 0.001, respectively), distance exotropia control (mean improvement, 0.6 points; P ≤ 0.001), and distance exodeviation magnitude (mean improvement, 2.2 Δ; P = 0.002). CONCLUSIONS: Among children 3 to 10 years of age with IXT for whom surgery was not considered to be the immediately necessary treatment, stereoacuity deterioration or progression to constant exotropia over 3 years was uncommon, and exotropia control, stereoacuity, and magnitude of deviation remained stable or improved slightly.

Comparison of the characteristics of patients with intermittent exotropia according to response to diagnostic monocular occlusion.

PURPOSE: To compare the characteristics of intermittent exotropia patients according to their response to the diagnostic monocular occlusion test. STUDY DESIGN: Retrospective study. METHODS: A retrospective review was performed of 141 patients with intermittent exotropia who had taken a monocular occlusion test before surgery. We classified the patients into 3 groups based on the response to monocular occlusion. The increase group was defined as those patients having an increase in deviation of ≥ 5 prism diopters (PD) after monocular occlusion as compared with the maximum measured angle. The decrease group was defined as those patients having a decrease in deviation of ≥ 5 PD. Otherwise, patients were classified as having no change. The patients' characteristics were compared among the groups. RESULTS: At distance fixation, 9 patients (6.5%) were classified as increase, 92 patients (66.7%) as no change, and 37 patients (26.8%) as decrease after monocular occlusion. At near fixation, 50 patients (35.5%) were classified as increase, 65 patients (46.1%) as no change, and 26 patients (18.4%) as decrease. At distance fixation, no significant differences were found between the parameters of the patients in the increase group and those of the patients in the other 2 groups. In patients with a small maximum angle of exodeviation at near fixation and with few visits, the deviation at near fixation significantly increased after diagnostic occlusion. CONCLUSION: Fifty-two patients (36.8%) showed an increase of ≥ 5 PD during distance or near fixation after monocular occlusion. In patients with a small maximum angle at near fixation and with few visits, it would be beneficial to perform the monocular occlusion test before surgery to reveal the maximal deviation angle, regardless of exotropia type.

The Effect of Preoperative Occlusion Therapy on Long-term Outcome after Surgery for Early-onset Exotropia.

PURPOSE: To investigate the effect of preoperative part-time occlusion therapy on long-term surgical success in early-onset exotropia. METHODS: The medical records of patients who underwent surgery for exotropia with onset before the first year of age and who were followed for ≥3 years were reviewed. Patients were divided into two groups according to the degree of compliance with part-time occlusion therapy: the good compliance group (>50% adherence rate) and the poor compliance group (≤50% adherence rate). Surgical success was defined as orthophoria to exodeviation less than 10 prism diopters both at distance and near. The level of postoperative stereopsis was compared between the two study groups among total enrolled patients and among those with constant exotropia. RESULTS: Of the 51 patients, 26 were assigned to the good compliance group and the remaining 25 patients to the poor compliance group. The surgical success rate was significantly higher in the good compliance group than in the poor compliance group (80.8% vs. 52.0%, p = 0.040). Among 24 constant exotropia patients (12 patients for each group), the success rate was insignificantly higher in the good compliance group than in the poor compliance group (75.0% vs. 58.3%, p = 0.448). The good compliance group had a better level of stereopsis than the poor compliance group (p = 0.045 for all 44 patients, p = 0.020 for 19 patients with constant exotropia). CONCLUSIONS: Preoperative part-time occlusion therapy was useful for improving the surgical outcome of early-onset exotropia and postoperative stereopsis.

[Intermittent Exotropia]. / Intermittierende Exotropie.

Intermittent exotropia (IXT) is a congenital form of divergent strabismus. Its incidence is estimated to be 32 per 100 000. Most often, IXT is first noted in early childhood when intermittently manifest outward deviation of the eyes is seen. Patients with IXT can control the deviation and keep the eyes aligned; this ability can be measured with "control scores". Complications such as amblyopia and loss of binocular functions are rare but should be looked for and need to be avoided. IXT can have a negative impact on quality of life. Conservative treatment includes the correction of refractive errors, (alternating) occlusion, over-minus lenses and orthoptic exercises. By injecting an extraocular muscle with botulinum toxin (to weaken its function) or with bupivacaine (to strengthen its function), IXT can be treated pharmacologically. Diagnostic occlusion and prism adaptation are strategies to uncover the true (largest) angle. Eye muscle surgery aims at eliminating the condition, but recurrences are common. The literature on large, randomized prospective trials for IXT is scarce. However, there are trials underway in the United Kingdom and in North America to better understand the natural course of IXT and to determine the most appropriate therapeutic approach.

An external pilot study to test the feasibility of a randomised controlled trial comparing eye muscle surgery against active monitoring for childhood intermittent exotropia [X(T)].

INTRODUCTION: The evidence base for the treatment of strabismus (squint) is poor. Our main aim is to improve this evidence base for the treatment of a common type of childhood squint {intermittent exotropia, [X(T)]}. We conducted an external pilot study in order to inform the design and conduct of a future full randomised controlled trial (RCT). METHODS: Children of between 6 months and 16 years with a recent diagnosis of X(T) were eligible for recruitment. Participants were recruited from secondary care at the ophthalmology departments at four UK NHS foundation trusts. Participants were randomised to either active monitoring or surgery. This report describes the findings of the Pilot Rehearsal Trial and Qualitative Study, and assesses the success against the objectives proposed. RECRUITMENT AND RETENTION: The experience gained during the Pilot Rehearsal Trial demonstrates the ability to recruit and retain sites that are willing to randomise children to both trial arms, and for parents to agree to randomisation of their children to such a study. One child declined the group allocation. A total of 231 children were screened (expected 240), of whom 138 (60%) were eligible (expected 228: 95%) and 49 (35% of eligible) children were recruited (expected 144: 63% of eligible). Strategies that improved recruitment over the course of the trial are discussed, together with the reasons why fewer children were eligible for recruitment than initially anticipated. Attrition was low. Outcome data were obtained for 47 of 49 randomised children. TRIAL PROCESSES AND DATA COLLECTION: The Trial Management processes proved effective. There were high levels of completion on all of the data collection forms. However, the feedback from the treatment orthoptists revealed that some modifications should be made to the length and frequency of the health service assessment and travel assessment questionnaires, thus reducing the burden on participants in the main trial. Modifications to the wording of the questions also need to be made. MONITORING OF BIAS: Children who recruited to the trial were older and had more severe strabismus than those children eligible but declining participation. Strategies to account for this in a full trial are proposed. REASONS FOR PARTICIPATION OR DECLINING STUDY: These were identified using qualitative interviews. The principal reasons for declining entry into the study were strong preferences for and against surgical treatment. HARMS: There were no serious unexpected adverse events. Two children had overcorrection of their X(T) with reduction in binocular vision following surgery, which is in line with previous studies. No children in the active monitoring arm developed a constant strabismus although two showed some reduction in control. CONCLUSIONS: The SamExo study has demonstrated that it is possible to recruit and retain participants to a randomised trial of surgery compared with active monitoring for X(T). For longer-term full RCTs, in order to maximise the generalisability of future studies, consideration needs to be given to planning more time and clinic appointments to assess eligibility and to allow consideration of participation; the greater use of research nurses for recruitment; and accommodating the strong preferences of some parents both for and against surgical intervention. TRIAL REGISTRATION: Current Controlled Trials ISRCTN44114892. FUNDING: This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 19, No. 39. See the NIHR Journals Library website for further project information.

Surrendering control, or nothing to lose: Parents' preferences about participation in a randomised trial of childhood strabismus surgery.

BACKGROUND: Intermittent exotropia is the most common form of divergent strabismus (squint) in children. Evidence regarding its optimum management is limited. A pilot randomised controlled trial has recently been completed (Surgery versus Active Monitoring in Intermittent Exotropia trial) to determine the feasibility of a full randomised controlled trial. PURPOSE: To identify drivers for and barriers against parents' participation in Surgery versus Active Monitoring in Intermittent Exotropia and to seek their views on information received, the need for randomisation, and enhancing acceptability. METHODS: Multiple method qualitative study using semi-structured telephone interviews to explore parents' motivations and trial screening logs to provide an indication of common barriers. Exploratory thematic analysis identified key themes. RESULTS: A total of 48 interviews were conducted (14 participants; 34 non-participants). Barriers included no desire for surgery/preference to 'wait and see', wanting surgery immediately, feeling uncomfortable about 'surrendering control' over decision-making/being managed 'at random', lack of confidence in the effectiveness of surgery, believing the risks outweighed the benefits, and lack of trust. Drivers included desiring surgery, 'nothing to lose', benefits offsetting the risks, and being in a trial would result in better care. Some also mentioned 'doing their bit' for research. Suggestions for enhancing acceptability included allowing choice of treatment group, giving more time for decision-making, expanding on information given, and improving communication. Many felt the necessity of randomisation was adequately explained, but there was some indication that it was misunderstood. Information extracted from the screening logs of 80/89 eligible non-participants indicated the most prevalent barrier was not wanting surgery/preferring to observe (56%), followed by desiring surgery straightaway (15%). Opposition to randomisation/wanting to retain control was recorded in 9% of cases as was the belief that the child's squint was not severe enough to warrant surgery. LIMITATIONS: Interviews were not audio-recorded. Not all who consented to interview could be contacted, although the response/contact rate was good (48/62). A few parents did not provide reasons for refusing the trial. CONCLUSION: Opposition to surgery and concerns about surrendering control were common obstacles to participation, whereas parents keen for their child to undergo the operation but happy to defer tended to embrace a 'nothing to lose' attitude. Many non-participants would have consented if allowed to choose group, although most of these would have chosen observation. While most parents felt happy with information given and that randomisation was adequately explained, it is of concern that there may be some misunderstanding, which should be addressed in any trial. These findings will inform future trials in childhood exotropia, for example, consideration of preference arms and improving communication. Lessons learnt from the Surgery versus Active Monitoring in Intermittent Exotropia trial could prove valuable to paediatric and surgical trials generally.

A systematic review of the effectiveness of treatments in altering the natural history of intermittent exotropia.

Evidence of effectiveness of interventions for treatment of childhood intermittent exotropia, X(T), is unclear. We conducted a systematic review to locate, appraise and synthesise evidence of effectiveness, including twelve electronic databases, supplemented with hand searches and expert contact. We included randomised controlled trials, quasi-experimental and cohort studies with a comparison group examining interventions for divergence excess, simulated divergence excess or basic type X(T) in children, up to and including 18 years of age, followed for at least 6 months. Dual data extraction and critical appraisal were conducted and a narrative synthesis undertaken. Eleven studies satisfied the eligibility criteria. Seven examined the comparative effectiveness of two surgical procedures; four compared surgery with other interventions, including botulinum toxin A therapy, orthoptic exercises, occlusion, binocular vision training and watchful waiting. The evidence retrieved was of limited extent and quality with differences across studies in terms of outcome assessment and most appropriate time-point for measuring long-term outcomes. There were mixed outcomes when comparing unilateral recession/resection (R&R) with bilateral lateral rectus recession (BLR) on improving angle of deviation, which makes it difficult to recommend either surgical option with confidence. While non-surgical interventions appear less effective in terms of improving angle of deviation, they are rarely associated with adverse outcomes. Given the limited evidence base, better designed studies are required to address the question of the most effective management for treatment of childhood X(T). Importantly, consensus is required on what constitutes a successful outcome as well as agreement on how this should be measured.

The impact of prism adaptation test on surgical outcomes in patients with primary exotropia.

BACKGROUND: We aimed to determine the impact of the preoperative prism adaptation test (PAT) on surgical outcomes in patients with primary exotropia. METHODS: Thirty-eight consecutive patients with primary exotropia were enrolled. Pre-operative PAT was performed in 18 randomly selected patients (Group 1). Surgery was based on the angle of deviation at distance measured after PAT. The remaining 20 patients in whom PAT was not performed comprised Group 2. Surgery was based on the angle of deviation at distance in these patients. Surgical success was defined as ocular alignment within eight prism dioptres (PD) of orthophoria. RESULTS: Satisfactory motor alignment (± 8 PD) was achieved in 16 Group 1 patients (88.9 per cent) and 16 Group 2 patients (80 per cent) one year after surgery (p = 0.6; chi-square test). There were no statistically significant differences in demographic parameters, pre-operative and post-operative angle of deviation between the two groups (p > 0.05; Mann-Whitney U and chi-square tests). Nine patients in Group 1 (50 per cent) and two patients in Group 2 (10 per cent) had increased binocular vision one year post-operatively. A statistically significant difference was determined in terms of change in binocular single vision between the two groups (p = 0.01; chi-square test). CONCLUSION: Although the prism adaptation test did not lead to a significant increment in motor success, it may be helpful in achieving a more favourable functional surgical outcome in patients with primary exotropia.

Medical and surgical treatment of primary divergent strabismus.

PURPOSE: To evaluate the long-term effectiveness of different therapies applied in the past 30 years, both medical and surgical, and results, with the ultimate aim of determining which are the most appropriate criteria to indicate when and how to perform medical and surgical treatment in these patients. METHOD: A retrospective randomized study was conducted on 198 patients with primary divergent strabismus first seen in our clinic (IOC) in the last 36 years (1976-2012), with a mean follow-up of 8.38 years. Demographic and clinical characteristics, as well as the various treatments performed, and motor and sensory outcome were collected. They were finally divided into 3 groups of 70, 71 and 56 patients, respectively, according to their first visit, in order to compare the therapies applied. RESULTS: Half (50%) of our patients debuted before 2 years of age (P50=24 months), and 26.3% had optimal binocular vision at the beginning of the study. Medical treatment was used as exclusive therapy in 29.3% of cases (occlusion therapy, applying negative lenses, botulinum toxin), and 70.7% required surgery (61.2% by double retro-insertion of lateral rectus, and 38.8% monolateral retro-resection). There was a recurrence in 26.7% of patients, and 40 re-interventions were performed (70% due to recurrence of divergent strabismus, 12.5% due to surgical over-correction, and 17.5% for other reasons). In the end, 61.1% of patients had perfect binocular vision (TNO=60"), and the proportion was higher in patients who showed proper control of their strabismus at the beginning (P=.003). However, no differences were found in the other variables studied. When the patients were divided into 3 groups (which are demographically comparable), an increased number of patients in Group 3 were found to be treated using negative lenses and botulinum toxin (P<.001 and P=.003). This group was found to have had a higher proportion of bilateral surgery (P=.032), seeking greater immediate postoperative over-correction, thus reducing the number of re-interventions from 40.5 to 19%, although it did not reach statistical significance (P=.093). It was also found that there was a significantly increased number of injections of botulinum toxin in the middle rectum for treatment of excessive postoperative overcorrection (P=.028). No other differences in final binocular vision was found between the 3 groups (P=.703). CONCLUSIONS: In cases of clear ocular dominance, occlusion therapy must be applied twice daily on the dominating eye, in order to encourage divergent strabismus control and improve sensoriality. An attempt should be made to wait until patients reach four years of age before indicating surgical treatment, except in cases of a significant worsening of motor or sensory component. Bilateral surgery on both lateral rectus should be attempted, provided that patient characteristics allow this. A slight post-surgical overcorrection should be looked for in the immediate postoperative period, as this, in our experience, reduces the total amount of re-operations. When working on the middle rectus, remember that the elasticity of this muscle is the key factor for obtaining a proper post-surgical outcome, but a reliable measurement of this still cannot be made. In cases of excessive post-surgical over-correction, an injection of botulinum toxin should be applied to these poor elasticity muscles, in order to reduce the number of re-operations.

Effect of suppression during tropia and phoria on phoria maintenance in intermittent exotropia.

BACKGROUND: Treatment for intermittent exotropia X(T) aims to keep the eye in a phoric position and to maintain the phoria. However, maintenance of phoria is difficult even after treatment, and the cause is unclear. The aim of this study was to investigate the presence of suppression during tropia and/or phoria in X(T), and to determine how the suppression affected patient's ability to maintain phoria. METHODS: Medical records of 89 children with X(T) (mean age, 9.8 ± 2.7 years) were reviewed retrospectively. According to their previous treatment for X(T), the patients were divided into four groups and compared: untreated and under observation only (28 patients), surgical treatment (32 patients), orthoptic training (eight patients) and a combined treatment of surgery and orthoptic training (21 patients). Suppression during phoria was evaluated by a physiologic diplopia test, and suppression during tropia was evaluated by a convergence test or a cover test when fusion broke. Phoria maintenance was achieved if a phoric condition was maintained even when the fusion broke at both near and far. Furthermore, the Bagolini's red filter bar was used to quantitatively assess patient's ability to maintain phoria at near and far distances. RESULTS: No subject only suppressed during phoria. Patients who suppressed under both conditions could not maintain phoria. Suppression under both conditions significantly correlated with phoria maintenance and the ability to maintain phoria (P < 0.01, Fisher's exact probability test). All the patients with a strong ability to maintain phoria did not suppress under either condition. As compared to the surgical treatment group, the combined treatment group had a higher percentage of patients who did not suppress under either condition and could maintain the phoria. Suppression under both conditions also significantly correlated the treatment methods (P < 0.01, Chi-square for the independence test). CONCLUSIONS: Suppression under both tropic and phoric conditions significantly relates to the outcome of patients' phoria maintenance and their ability to maintain a phoric position. Suppression under both conditions is an important indication of whether X(T) shifts to constant exotropia.