Intermittent Exotropia Research Articles

First-finder-related Clinical Features of Intermittent Exotropia

Purpose: To determine whether the clinical features of intermittent exotropia (IXT) needing muscle surgery were different in the ophthalmologist-detected and non-specialist-detected groups (including parents).Methods: Medical records of 218 children (mean age: 5.9 ± 1.4 years) with IXT of ≥ 20 prism diopters (PD) were reviewed retrospectively. The angles of deviation were measured using the prism and alternate cover test and assessed by two ophthalmologists using photographs with a translucent occluder (photographic angle). The IXT subtype, fusional control, stereopsis, suppression, and spherical equivalent (SE) were compared between the ophthalmologist-detected and non-specialist-detected groups.Results: Mean 25.8 ± 6.8 PD of distant angle of IXT was first detected by the ophthalmologist in 41 patients (18.8%) and the non-specialists in 177 patients (81.2%). The deviated eye was more myopic in the ophthalmologist-detected than non-specialist- detected group (-0.77 ± 1.59 diopters [D] vs. -0.19 ± 1.48 D, <i>p</i> = 0.03). There were no other differences between the two groups. A comparison of 39 age- and non-dominant eye SE-matched pairs demonstrated that the measured angles for distant and near fixation were smaller in the ophthalmologist-detected than non-specialist-detected group (24.0 ± 6.8 PD vs. 28.5 ± 6.4 PD and 26.9 ± 6.6 PD vs. 31.0 ± 6.4 PD, respectively, <i>p</i> < 0.01), while the remaining characteristics, including the photographic angle, were similar.Conclusions: In cases with small angles of deviation or myopia, IXT with angles requiring surgical correction were commonly first detected by ophthalmologists during examinations.

Binocular contrast sensitivity in patients with intermittent exotropia in relation to angle of strabismus and level of compensation

ABSTRACT Intermittent exotropia (IXT) causes photophobia, and photophobia has been studied by measurement of contrast sensitivity (CS). CS was reduced in children with IXT. We compared binocular CS (BCS) in patients with IXT and normal subjects in relation to the angle of strabismus and control of IXT. This case–control study was performed on 40 patients with IXT and 40 normal subjects who were examined with the CSV1000 CS device in mesopic (3 cd/m2) and photopic (85 cd/m2) conditions with and without a glare stimulus at 3, 6, 12, and 18 cycle/degree (cpd) spatial frequencies. The angle of strabismus and near stereoacuity were also measured. The patient’s IXT compensation was graded based on the office control scale. The mean age for IXT and normal participants were 12.30 ± 0.60 (range, 6–18) and 11.00 ± 0.78 (range, 6–18) years, respectively (P = .34). The IXT patients had lower binocular CS than controls at all spatial frequencies (P < .001). The largest decrease in CS occurred at 6 cpd spatial frequency under mesopic condition (1.61 ± 0.07 vs 1.38 ± 0.15, P < .001) and photopic condition with glare (2.03 ± 0.06 vs 1.77 ± 0.13, P < .001). Patients with better control scores had higher levels of BCS; also, the score of BCS showed a significant decrease in patients with a deviation of 25 prism diopter or more, compared to those with less deviation. BCS correlated at 3 and 6 cpd with near stereoacuity (r = −0.652, P < .001 and r = −0.613, P < .001). Binocular CS in patients with IXT correlates with the angle of strabismus and level of compensation.

Binocular function in patients with intermittent exotropia accompanied by unilateral congenital ptosis

Patients with intermittent exotropia (IXT) have a wide range of binocular deficits. This study aims to evaluate the effect of ptosis on the binocular function of patients with IXT. Clinical records of 45 IXT patients with congenital ptosis (IXT-ptosis group) and 58 age-matched IXT patients without ptosis (IXT only group) who presented for eye examination between January 2017 and June 2020 were retrospectively reviewed. Patients with amblyopia were excluded to rule out the effects of visual acuity on binocularity. Best-corrected visual acuity (BCVA), the magnitude of exodeviation at distance and at near, stereopsis, and office-based control scores at the first visit were reviewed. The binocular functions of the two groups were compared. The mean ± SD age of the overall patients was 6.6 ± 2.7 years. There were no significant differences in the distribution of age, sex, spherical equivalent refraction, or BCVA between the two groups (all p > 0.05). Although the office-based control scores at distance and near were slightly worse in the IXT-ptosis group, the differences were not statistically significant (at distance, 2.8 ± 1.87 vs. 2.2 ± 1.13, p = 0.08; at near, 1.8 ± 0.67 vs. 1.6 ± 0.74, p = 0.11). Furthermore, the IXT-ptosis group had worse stereopsis at distance (p = 0.01). There were no significant differences between the two groups in near stereopsis or exodeviation magnitude (p > 0.05). A larger proportion of patients had suppression on the Bagolini test in the IXT-ptosis group than in the IXT-only group (p = 0.04). The IXT-ptosis group had worse distance stereoacuity, and a larger proportion of patients had suppression on the Bagolini test than the IXT only group. In IXT patients, the presence of coexisting ptosis can have a further deleterious impact on binocular function.

Analysis of Facial Features of Patients With Sagging Eye Syndrome and Intermittent Exotropia Compared to Controls

To compare the facial features of patients with sagging eye syndrome (SES) and other ophthalmic diseases, and to evaluate the diagnostic usefulness of facial features for SES. Retrospective cross-section study. We evaluated frontal facial photographs of patients >60 years of age with SES and intermittent exotropia (IXT), and control patients who visited the ophthalmology outpatient clinics of 2 institutions between June 2020 and December 2021. Three ophthalmologists evaluated each eye for sunken upper eyelid, blepharoptosis, and baggy lower eyelid, using a scoring scale. The average scores for each parameter among the 3 groups were analyzed. Patients with glaucoma, visual acuity <16/20, SES with a vertical strabismus angle of ≥6 Δ, IXT that could not be maintained in the phoria position during photography, a history of previous oculoplastic or ophthalmic surgery, and use prostaglandin analogs for cosmetic purposes were excluded. A total of 86 patients were included: 23 with SES, 28 with IXT, and 35 in the control group. All were Japanese. In all, 45 patients were male and 41 were female. The mean age was 72.7 ± 7.4 years. The sunken upper eyelid scores were significantly higher in the SES group than in the control and IXT groups (P < .001), whereas the baggy lower eyelid scores were significantly higher in the IXT group than in the control group (P < .05). Age-related orbital connective tissue degeneration may manifest as SES in the upper eyelid and as IXT in the lower eyelid.

Botulinum toxin augmented bilateral lateral rectus recession versus three muscles surgery in large-angle intermittent exotropia.

To report the surgical outcomes of correcting large angle intermittent exotropia in adult patients by bilateral lateral rectus muscle recession with intraoperative use of botulinum toxin and to compare the results with those of bilateral lateral rectus muscle recession and unilateral medial rectus resection. The medical records of patients who underwent surgical correction of large angle intermittent exotropia [exotropia >50 prism dioptre (PD)] were retrospectively reviewed. Two groups of patients were identified; Group I (21 patients) had bilateral lateral recti recession augmented with intraoperative botulinum toxin A (BTA) injection into the recessed muscles and group II (30 patients) were treated by bilateral lateral recti recession with unilateral medial rectus muscle resection. Preoperative data were extracted for age, gender, refraction, type of exotropia, angle of stereopsis and angle of deviation. The main outcome measures were the postoperative angle of deviation and stereoacuity angle by Titmus test measured at the end of one year of postoperative follow up. By the end of the first postoperative year, 10 patients in group I (47.6%) and 20 patients in group II (66.7%) achieved esotropia/esophoria <5 PD or exotropia/exophoria <10 PD. The difference in surgical success rate was not statistically significant (P=0.1) but there was a statistically significant higher rate of undercorrection in group I (P=0.03). On the other hand, 3 patients in group I (14.3%) and 5 patients in group II (16.7%) had improved stereopsis; this difference in the sensory outcome was not statistically significant (P=0.8). In the BTA augmented surgery group, good stereoacuity and smaller preoperative angle of deviation were associated with significantly higher surgical success rate (P=0.004, 0.01 respectively). BTA augmented bilateral lateral recti recession is associated with higher rate of undercorrection as compared to bilateral lateral recti recession with unilateral medial rectus resection in the correction of large angle intermittent exotropia. The surgical success rate in BTA augmented surgery group is observed to be higher in patients with preoperative smaller angle of deviation and in patients with good stereoacuity.

Comparison of Surgical Outcomes of Two-muscle Surgery in Children with Large-angle Intermittent Exotropia

Purpose: To evaluate the long-term results of 2-muscle surgery in children with large-angle intermittent exotropia (IXT), comparing bilateral lateral rectus recession (BLR) with unilateral lateral rectus recession &amp; medial rectus resection (RR).Methods: Ninety-two children with IXT of 40 prism diopter or more, who underwent BLR or RR were included in this retrospective study. Final successful alignment rates, and cumulative probabilities of surgical success at 3 years postoperatively were analyzed and compared using Kaplan-Meier survival analysis between the two groups.Results: At 3 years after surgery, 37 (67.3%) of 55 patients in the BLR group achieved successful alignment; 18 (32.7%) had undercorrection, and none of them had overcorrection. In the RR group, 34 (92%) of 37 patients were successfully aligned, two (5%) had undercorrection, and one (3%) had an overcorrection at 3 years after surgery. There was a statistically significant difference in postoperative results between the two groups (p = 0.0012). The cumulative probabilities of surgical success at 3 years postoperatively analyzed using the Kaplan-Meier survival curve were 63% in the BLR group and 92% in the RR group. Postoperative mean recurrence time was 45 months in the BLR group and 50 months in the RR group, showing a significant difference between the two groups (p = 0.0006).Conclusions: The unilateral RR procedure demonstrated more favorable long-term postoperative outcomes than BLR procedure in patients with large-angle IXT.

Effect of Spectacle Lenses with Highly Aspherical Lenslets on Binocular Vision and Accommodation in Myopic Children with and without Intermittent Exotropia.

Purpose To evaluate the influence of spectacle lenses with highly aspherical lenslets (HAL) on binocular vision and accommodation in myopic children with intermittent exotropia (IXT) and compare the changes after wearing HAL in binocular vision and accommodation in myopic children with or without IXT. Method Forty myopic subjects aged 8–12 years were recruited: 20 with IXT and 20 visually normal children. Stereoacuity, phoria, accommodative facility, fusional vergence, vergence facility, near point of convergence, amplitude of accommodation, and accommodative response (AR) were measured by wearing HAL or single vision spectacle lenses (SVL) in a random order after adapting for 20 minutes. Accommodative microfluctuation (AMF) was defined as the standard deviation of AR. Changes in binocular vision and accommodation after wearing HAL were compared between the two groups. Results No significant differences were found in binocular vision after wearing HAL versus SVL in either group (all P > 0.05). A greater AMF was found after wearing HAL than after wearing SVL in both groups (0.04 D, 95% confidence interval (CI), 0.03 to 0.05 D, P < 0.001 for the IXT group; 0.05 D, 95% CI, 0.03 to 0.07 D, P < 0.001 for the visually normal group); however, the other accommodation parameters did not change significantly (all P > 0.05). There were no differences in the changes after wearing HAL in any parameter between the two groups (all P > 0.05). Conclusion HAL did not significantly change the binocular vision and accommodation for myopic children with or without IXT except for AMF in the short term.

How to Better Treat Patients with Intermittent Exotropia: A Review of Surgical Treatment of Intermittent Exotropia.

Intermittent exotropia (X(T)) is the most common form of strabismus, especially in Asians. Treatment of X(T) includes occlusion, overminus lens, and surgery, of which, surgery is the mainstay of treatment. Commonly performed surgical procedures for X(T) are bilateral lateral rectus muscle recession or unilateral lateral rectus recession with medial rectus resection; however, it is unclear which of the two surgeries is more effective. The purpose of this review is to provide an insight on the surgical treatment of X(T). Randomized controlled trials, comparative observational studies, and case series with a large number of patients as well as a long follow-up period of over a year were included.

Abnormal cortical morphology in children and adolescents with intermittent exotropia.

PurposeTo investigate cortical differences, age-related cortical differences, and structural covariance differences between children with intermittent exotropia (IXT) and healthy controls (HCs) using high-resolution magnetic resonance imaging (MRI).MethodsSixteen IXT patients and 16 HCs underwent MRI using a 3-T MR scanner. FreeSurfer software was used to obtain measures of cortical volume, thickness, and surface area. Group differences in cortical thickness, volume and surface area were examined using a general linear model with intracranial volume (ICV), age and sex as covariates. Then, the age-related cortical differences between the two groups and structural covariance in abnormal morphometric changes were examined.ResultsCompared to HCs, IXT patients demonstrated significantly decreased surface area in the left primary visual cortex (PVC), and increased surface area in the left inferior temporal cortex (ITC). We also found increased cortical thickness in the left orbitofrontal cortex (OFC), right middle temporal cortex (MT), and right inferior frontal cortex (IFC). No significant differences were found in cortical volume between the two groups. There were several negative correlations between neuroanatomic measurements and age in the HC group that were not observed in the IXT group. In addition, we identified altered patterns of structural correlations across brain regions in patients with IXT.ConclusionTo our knowledge, this study is the first to characterize the cortical morphometry of the children and adolescents with IXT. Based on our results, children and adolescents with IXT exhibited significant alterations in the PVC and association cortices, different cortical morphometric development patterns, and disrupted structural covariance across brain regions.

Correlation between Limbal Insertion Distance and Surgical Effect of Lateral Rectus Recession in Cases of Intermittent Exotropia

Correlation between Limbal Insertion Distance and Surgical Effect of Lateral Rectus Recession in Cases of Intermittent Exotropia

Effect of Mild to Moderate Myopic Refractive Error on Surgical Outcomes of Intermittent Exotropia in Children

Purpose: We evaluated the effect of myopia on lateral rectus recession in children with intermittent exotropia.Methods: Medical records of patients with mild to moderate myopia who underwent lateral rectus recession for intermittent exotropia surgery were retrospectively reviewed. Patients were grouped into three groups according to their spherical equivalents (SEs) (group 1: SE &gt; -1.0 diopter [D]; group 2: -3.0 D &gt; SE ≥ -1.0 D; group 3: SE ≤ -3.0 D). The success rate of surgery after 1 month, 3 months, and 12 months, and the degree of correction were reviewed. Surgeries were considered successful if the amount of exo/eso-tropia or phoria was within +10/-10 prism diopters (PD) after 12 months.Results: There were no significant differences in mean exodeviation at any time point among the three groups. The degree of correction per lateral muscle recession (PD/mm) was 2.05 ± 0.40, 2.33 ± 0.57, and 2.00 ± 0.30; 2.13 ± 0.46, 2.06 ± 0.26, and 2.14 ± 0.13; and 1.93 ± 0.47, 2.11 ± 0.32, and 1.92 ± 0.25 at 1, 3, and 12 month(s) after surgery in the three groups; however, the results were statistically significant at 3 months only. The surgical success rate was 81.82%, 100%, and 100% in the groups, respectively, with no significant differences among groups.Conclusions: There was no difference in the surgical success rate or degree of correction among groups with mild to moderate myopia. No additional surgical correction is needed in myopic patients with intermittent exotropia.

Assessment of distance-near control disparity in basic and divergence excess paediatric intermittent exotropia

ABSTRACT Clinical Relevance In intermittent exotropia (IXT), deviation is better controlled at near fixation. Understanding of the mechanism responsible for this common observation may improve clinical management of IXT. Background The physiological basis for the distance-near difference in control of deviation in IXT is vastly undetermined. A new parameter, ‘control score disparity (CSD)’, defined as the difference between distance and near control scores, is introduced. Association of CSD with positive fusional amplitude (PFA), accommodative convergence to accommodation (AC/A) ratio and distance angle of deviation was investigated to further understand the mechanisms. Method Patients aged between four and fifteen years with basic and divergence excess IXT were included. Subjects with previous strabismus surgery, amblyopia and inability to perform clinical tests were excluded. A standardized office-based scoring system was used to assess IXT controls. Subjects were sub-divided into group 1 (CSD <2) and group 2 (CSD ≥2). Pearson’s univariate and regression analysis were used to determine relationships between CSD and other independent variables. Results Mean age of the total 141 subjects (57.6% female) was 6.8 ± 2.5 years. Basic IXT was more common (60%) and 60% had CSD ≥2. The mean±SD distance angle of deviation, AC/A ratio, PFA and CSD were 22.1 ± 6.6 prism dioptres, 5.0 ± 1.0, 28.6 ± 6.3 prism dioptre and 2.0 ± 0.5, respectively. CSD was significantly correlated to PFA (r = 0.64, p < 0.001) and AC/A ratio (r = 0.27, p < 0.001) in overall samples and Group 2 subjects (r = 0.41, p = 0.001). Conclusions PFA is a major factor associated with the distance/near difference of IXT control. Individuals with a higher PFA demonstrated greater CSD. While AC/A ratio was associated in better control at near in divergence excess IXT, magnitude of angle appears irrelevant.

Treatment of convergence insufficiency type intermittent exotropia with bupivacaine injection to the medial rectus combined with lateral rectus recession

PurposeTo evaluate the outcomes of combined bupivacaine HCL (BPX) injection in the medial rectus (MR) muscle with recession of the lateral rectus muscle in the treatment of convergence insufficiency–type intermittent exotropia (CI-IXT). MethodsThe medical records of patients who underwent combined injection-recession treatment from January 2019 to January 2020 for CI-IXT were reviewed retrospectively along with a group of age-matched controls with IXT without CI who underwent only unilateral LR recession during the same period. The following data were extracted from the record: age at surgery, average follow-up period, angle of deviation at distance and near and the difference between them before and after surgical procedure, correction of near and distance deviations, and recession dosage. Successful outcome was defined as a distance deviation in primary gaze between ≤10Δ of exophoria/tropia and ≤5Δ of esophoria/tropia. ResultsA total of 10 patients and 20 controls were included. Average follow-up was 13.9 ± 3.67 months in the BPX group and 15.9 ± 3.61 months in the control group (P = 0.17). Postoperative distance deviation measured 8.30Δ ± 5.88Δ in the BPX group and 14.67Δ ± 9.83Δ in the control group (P = 0.80). Distance-near differences were significantly reduced in the CI-IXT group receiving BPX, by a mean of 6.60Δ, from a preoperative mean of 10.50Δ ± 3.65Δ to 3.90Δ ± 3.26Δ (P < 0.01). ConclusionsBPX injection combined with unilateral lateral rectus recession yields outcomes comparable to bilateral lateral rectus recession for distance deviations, and results in reduction of the distance-near difference in the angle of exotropia.

Comparative Study of Bilateral Versus Unilateral Strabismus Surgery in the Management of Lateral Incomitance in Intermittent Exotropia.

To evaluate and compare bilateral asymmetric lateral rectus recession versus unilateral resection-recession surgery in the management of lateral incomitance in intermittent exotropia. A prospective randomized interventional comparative study was conducted consisting of 80 patients with intermittent exotropia (older than 7 years) having significant lateral incomitance. They were equally divided into two groups by a sealed envelope system. The bilateral group underwent bilateral asymmetric lateral rectus recession and the unilateral group underwent unilateral lateral rectus recession and medial rectus resection based on post-patch deviation. Parameters assessed were change in horizontal deviation, change in lateral incomitance, binocularity, motility limitation, and complications, if any. Surgical outcome was considered successful if the primary deviation was within ±8 prism diopters (PD) and lateral incomitance was less than 5 PD. The mean lateral incomitance preoperatively and postoperatively was 8.3 ± 1.6 and 2.8 ± 2.4 PD in the bilateral group and 8.9 ± 1.4 and 3.7 ± 2.5 PD in the unilateral group, respectively. There was no statistically significant difference in the postoperative lateral incomitance between the two groups (P = .25), but a statistically significant difference was observed between preoperative and postoperative lateral incomitance in each group (P < .0001). Both procedures are equally efficacious in achieving acceptable ocular alignment and improving significant lateral incomitance in patients with intermittent exotropia with deviations between 15 and 35 PD without causing significant motility limitation. [J Pediatr Ophthalmol Strabismus. 2023;60(4):277-281.].

How does patching compare with observation for children with intermittent exotropia?

How does patching compare with observation for children with intermittent exotropia?

Intermittent exotropia: a novel surgical algorithm based on a postocclusion distance-near relationship

For the preoperative evaluation of patients with intermittent exotropia, prior studies have revealed that prism alternate cover testing at distance and at near should be performed after a period of monocular occlusion, and that the use of a reading add at near helps to exclude accommodative convergence. Using these evaluation techniques, a performance improvement project was undertaken to evaluate a dosage-modification algorithm created to improve outcomes with bilateral lateral rectus recession surgery.

Standard versus reduced numbers for the management of intermittent exotropia in children ≤6 years

Reduction of the surgical dose in intermittent exotropia in younger age groups might reduce the rate of consecutive esotropia and improve the success rate. The aim of the study was to compare using the standard surgical dose versus a reduced surgical dose in intermittent exotropia in children ≤6 years, and to determine whether this outcome is influenced by the degree of preoperative control.

Understanding the use of control scores in intermittent exotropia: Newcastle, PEDIG, and LACTOSE

The Newcastle, PEDIG, and LACTOSE control scores for intermittent exotropia (IXT) were developed to quantify control of exodeviations. These scores may be used to monitor disease progression, guide treatment including surgical intervention, and ensure uniformity of reporting in studies of IXT. However, it is unclear whether pediatric ophthalmologists have adopted these control scores in clinical practice.

Comparison of sensory outcomes in patients with successful motor outcome versus recurrent exotropia after surgery for intermittent exotropia

Here, we compared sensory outcomes between patients with successful motor outcomes and recurrent exotropia after intermittent exotropia surgery. We retrospectively analyzed 303 patients who underwent surgery for intermittent exotropia, divided into two groups: successful motor outcome defined as an alignment between 10 prism diopters (PD) exodeviation and 5PD esodeviation at the final follow-up (Group A, n = 177) and residual or recurrent exotropia defined as exodeviation > 10 PD (Group B, n = 126). Preoperative and postoperative (at final visit) sensory outcomes were compared using the Titmus stereotest and distance Worth 4-dot test. Stereoacuity significantly improved postoperatively in both successful motor outcome group (Group A) and residual or recurrent exotropia group (Group B). However, stereoacuity did not differ between groups preoperatively and postoperatively. On the other hand, fusion rates for the Worth 4-dot test were significantly higher in group A than in group B, preoperatively and postoperatively, and significantly increased postoperatively only in group A. Therefore, the distance Worth 4-dot test may be useful for evaluating postoperative prognosis and preoperative sensory status.

Results of fusional vergence therapy in managing consecutive esotropia: A case series.

To analyze the efficacy of fusional vergence therapy (FVT) in management of consecutive esotropia with diplopia after intermittent exotropia (IXT) surgery. The current study is carried on how FVT affects the duration of treatment, sensory fusion, and exotropic drift. This was a retrospective study for the medical record of 11 patients with consecutive esotropia after IXT surgery of 543 patients over the period of 5 year, with mean surgery age of 9.5 (range: 4-33 y). FVT was planned after minimum 6 weeks of surgery and was considered for maximum 24 weeks. Patients underwent a combination of office-based and home-based FVT. Successful outcome of therapy was considered where diplopia resolves in free space and achieves sensory fusion, stereopsis with no manifest deviation. Record of 543 patients who had horizontal muscle surgery for IXT were identified and reviewed. Records of 11 patients who showed consecutive esotropia of 10 prism diopter (PD) or more with normal retinal correspondence, with or without diplopia complaint, after 6 week of surgery and had undergone vision therapy management were reviewed. A successful outcome of binocular single vision with good sensory and motor fusion with no manifest deviation or prism requirement was achieved with in the mean duration of 4.8 month of therapy. With a mean duration of 4 weeks of therapy, the mean angle of deviation reduced by 53% for distance (17 PD to 8 PD) and 27% for near (11 PD to 8 PD) and mean stereopsis improvement by 80% with 94% patients demonstrating sensory fusion on Bagolini test and 94% of patients having no symptoms of diplopia or squint. With nonsurgical management involving refractive error correction, FVT, and prism, consecutive esotropia was resolved in 74% cases. Management of consecutive esotropia with FVT can result in satisfactory sensory fusion and successful motor alignment.