Course Of Intermittent Exotropia Research Articles

Correct understanding of the non-surgical management options in the treatment of intermittent exotropia in children

Intermittent exotropia is the commonest type of strabismus, and surgery is the primary treatment. Follow-ups and other non-surgical management options can be used for patients who are younger, less cooperative, with well controlled exotropia, or unwilling to operate. However, there are many misconceptions regarding the treatment, especially the non-surgical treatment of intermittent exotropia in children, due to lack of thorough understanding about the natural course of intermittent exotropia, the timing for surgery, and the suitable candidates, effectiveness, and potential risks of different non-surgical options. This article provide an objective evaluation about the common non-surgical management options of intermittent exotropia based on the international research findings and clinical experience, in order to facilitate the correct understanding and rational use of the non-surgical treatment.

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

To describe the course of intermittent exotropia (IXT) in children followed up without treatment for 3 years. Observation arm from randomized trial of short-term occlusion versus observation. 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. 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. 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. 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). 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.

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

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

The Natural Course of Intermittent Exotropia over a 3-year Period and the Factors Predicting the Control Deterioration.

The natural course of intermittent exotropia and the factors affecting its control has been unclear. We aim to report the natural course of our cohort of 117 Chinese children with intermittent exotropia and to identify baseline parameters that may have predictive value in the control deterioration of the disease. The visual acuity, spherical equivalent, compliance to orthoptic exercise, angle of deviation fusional convergence parameters and Newcastle Control Score were recorded for all children at baseline and at 3 years apart. Patients were divided into two groups according to the change in control over the 3 years: group 1 included patients who had no deterioration or had improvement in disease control; and group 2 were those who had deteriorated control or had undergone surgery. There were 77 patients (66%) in group 1 and 40 (34%) patients in group 2. Comparing the baseline parameters of the two groups, group 1 had statistically significantly smaller angle of deviation, larger fusional reserve, larger fusional recovery, and higher fusional reserve ratio (p < 0.05). Other baseline parameters were similar between the two groups. The baseline fusional parameters may have predictive value in determining the control of intermittent exotropia.

The Stabilization of Postoperative Exo-drift in Intermittent Exotropia after Surgical Treatment.

PurposeTo investigate the long-term clinical course of intermittent exotropia after surgical treatment to determine whether and when postoperative exo-drift stabilizes, and the required postsurgery follow-up duration in cases of intermittent exotropia.MethodsWe retrospectively reviewed the medical records of patients diagnosed with intermittent exotropia who underwent surgical treatment between January 1992 and January 2006 at Yeungnam University Hospital and postoperatively performed regular follow-up examinations for up to 7 years. We also analyzed the difference in exo-drift stabilization, according to surgical procedure.ResultsA total of 101 patients were enrolled in the study. Thirty-one patients underwent lateral rectus recession and medial rectus resection (R&R) and 70 patients underwent bilateral lateral rectus recession (BLR). The postoperative angles of deviation increased significantly during the initial 36 months, but no subsequent significant changes were observed for up to 84 months. Follow-ups for 7 years revealed that more than 50% of the total amount of exo-drift was observed within the first postoperative year. In addition, the angles of deviation at 1 year correlated with those at 7 years postoperatively (Pearson correlation coefficient r = 0.517, p < 0.001). No significant exo-drift was observed after 36 months in patients who underwent BLR, whereas after 18 months in patients who underwent R&R.ConclusionsThe minimum postoperative follow-up required after surgical treatment to ensure stable results is 36 months. In particular, careful follow-up is necessary during the first postoperative year to detect rapid exo-drift. Patients who underwent BLR required a longer follow-up than those who underwent R&R to ensure stable postoperative alignment.

Intermittent Exotropia

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.

The Clinical Course of Intermittent Exotropia With Small Initial Deviation.

To address the clinical course of patients who initially presented with small exodeviation (≥ 10 and ≤ 18 prism diopters [PD]) and to investigate the risk factors associated with progression. The clinical records of patients who were first diagnosed as having intermittent exotropia of small initial deviation from August 2008 to March 2011 and were followed up for 2 or more years were reviewed retrospectively. The initial clinical features associated with the risk of disease progression and surgical intervention were analyzed. Among 86 patients who met the inclusion criteria, 37 reached a distance deviation of 20 PD or greater and 51 underwent surgical correction for exodeviation during the follow-up. Cumulative percentages of patients whose distance deviation reached 20 PD or greater and who underwent surgery at 24 months were 47.5% and 47.7%, respectively. Mean initial stereoacuity was significantly worse in patients whose final exodeviation progressed to 20 PD or greater. The cumulative probability of surgery was significantly higher in patients who showed constant deviation at the initial examination. Nearly half of patients with small exodeviation are expected to reach a final distance deviation of 20 PD or greater or to undergo surgery after 2 years of follow-up. Initial constant deviation was associated with increased cumulative probability of surgical intervention.

The operation time and post-operative target eye alignment of intermittent exotropia

Different from other types of strabismus, children with intermittent exotropia can maintain normal eye alignment and binocular vision in a long period of time. But the course of intermittent exotropia is mostly progressive, the eye position may drift outward even after surgery, so there is a certain risk of recurrence or under correction. These features often lead confusion to the clinicians in determining the operation time and postoperative target eye position. So how to choose the appropriate intervention time and target eye alignment is a challenge for clinicians. In this paper, we will combine the research status and clinical practice, discuss these issues, and present some point of view for the peer reference.

Classification and Misclassification of Sensory Monofixation in Intermittent Exotropia

The course of intermittent exotropia and response to surgery may depend on whether there is underlying monofixation. The purpose of this study was to report the prevalence of sensory monofixation in intermittent exotropia using different stereotests and to determine the risk of misclassifying monofixation based on a single administration of each test. Retrospective case review of children with intermittent exotropia. Forty-four children were identified for whom Preschool Randot, Frisby, and Titmus stereoacuity were measured at a single examination. Ninety-two children were identified with near stereoacuity measured on 2 sequential visits (Preschool Randot, n = 73; Frisby, n = 66; and Titmus, n = 40). Monofixation was defined as stereoacuity worse than previously published age-referenced normal thresholds, bifixation was defined as at least 40 arc seconds, and uncertain was defined as within normal range for age but worse than 40 arc seconds. In children measured by all 3 tests on the same visit, sensory monofixation occurred in 36% using Preschool Randot, in 48% using Titmus, and in 55% using Frisby (P > .1 for each comparison). There was poor agreement between Frisby and Preschool Randot when classifying monofixation in individual patients (P = .05). In children measured on sequential visits, misclassification occurred in 5% with Preschool Randot, in 13% with Titmus, and in 23% with Frisby (Preschool Randot vs Frisby, P = .005). Classification of monofixation depends on the stereotest used. Regardless of the stereotest, there is a risk of misclassifying monofixation on a single assessment. Potential misclassification needs to be considered in clinical practice and in study design.

The Course of Intermittent Exotropia in a Population-Based Cohort

The Course of Intermittent Exotropia in a Population-Based Cohort

The Course of Intermittent Exotropia in a Population-Based Cohort

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. Retrospective, population-based observational study. 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. The medical records of all potential patients identified by the resources of the Rochester Epidemiology Project were reviewed. The change in the angle of deviation and its association with treatment were reviewed for each patient. 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. 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.

The clinical course of intermittent exotropia.

To report the clinical course for patients with intermittent exotropia. The clinical records of patients diagnosed with intermittent exotropia from 1983 to 1991 who had at least 4 years of follow-up were reviewed. All patients with neurological or medical abnormalities, developmental delays, ocular disease, or having strabismus surgery during the follow-up period were excluded. Of the 468 records reviewed, 73 met the inclusion criteria. Forty-four patients were female, and 29 were male. Fifty-two patients had basic intermittent exotropia, 11 patients had divergence excess intermittent exotropia, and 10 patients had convergence insufficiency intermittent exotropia. The mean age at initial visit was 20 years (range, 1 to 63 years). The mean follow-up was 10 years (range, 4 to 23 years). Four patients had amblyopia of 20/30 or worse, nine patients had a vertical deviation in the primary position, and 10 patients had undergone extraocular muscle surgery before coming to our clinic. Sixty patients received some form of treatment during follow-up. The mean stereoacuity at the initial and final visits were 59 and 70 s arc, respectively. The initial mean spherical equivalent refraction was -0.48 D and increased to -1.15 D at the end of the study. The mean exodeviation changed from 17.2 Delta at distance and 17.6 Delta at near at the initial visit to 13.7 Delta at distance and 13.5 Delta at near at the final visit. At the initial visit, 63 patients were exotropic and 10 patients were either heterophoric or orthophoric at distance, whereas, 60 patients were exotropic and 13 patients were either heterophoric or orthophoric at near. At the final visit, 37 patients were exotropic and 36 patients were either heterophoric or orthophoric at distance whereas 33 patients were exotropic and 39 were either heterophoric or orthophoric at near. One patient was esotropic at near at the last visit. Changes in the size and quality of the exodeviation, although statistically significant (p < 0.001), were not associated with any specific treatment regimen or with longer periods of follow-up. Measurements exhibited a regression toward the mean. Intermittent exotropia improved for many patients quantitatively and qualitatively over time. That the improvement was unrelated to any treatment and length of follow-up suggests that the changes at least quantitatively are not associated with any physiologic process and may be due, in part, to regression toward the mean.