Combined recession and resection of the same lateral Rectus in the treatment of exotropia.

BACKGROUND: Besides rest position abnormalities, exotropia could also be due to hypertonia of the Lateral Recti (LR) given divergence frequently decreases under general anesthesia (GA). Combined Recession-Resection of the Same Muscle (RRSM) is a promising alternative to the Faden procedure in the surgical treatment of overacting MR in esotropia. We thus examined here the effectiveness of combined RRSM of the LR for the treatment of exotropia that decrease under GA. METHODS: We performed a retrospective, single-center evaluation over a 16-month period of 100 patients operated on for exotropia that decreased under deep GA (91% of 110 consecutive operated cases). We excluded re-operations and pure convergence insufficiencies. We performed a combined RRSM of one or two LR. It included a 10mm-recession and a "fine-tuned" resection of LR based on Quantitative Forced Duction Test scores. MR resection was combined when exotropia exceeded 35PD or for unilateral surgery. We report on patient outcomes 6 months after surgery. RESULTS: Successful results were obtained (-8-+8 PD measured on Alternate Cover Test) among 83% of cases at distance fixation and 91% at near fixation after 6 months. The Newcastle Control Score also improved from 5.8 to 1.7 after 6 months. No surgery-related complications or repeat surgeries were reported. CONCLUSIONS: In our experience a majority of exotropias decrease under GA and our strategy of combined RRSM of the LR is effective for the treatment of such exotropias. Long-term follow-up of the cohort is required to investigate the stability of these outcomes, and confirmation of our results by other works.

Functional changes in fusional vergence-related brain areas and correlation with clinical features in intermittent exotropia using functional magnetic resonance imaging.

To explore the functional changes of the frontal eye field (FEF) and relevant brain regions and its role in the pathogenesis of intermittent exotropia (IXT) children via functional magnetic resonance imaging (fMRI). Twenty-four IXT children (mean age, 11.83 ± 1.93 years) and 28 normal control (NC) subjects (mean age, 11.11 ± 1.50 years) were recruited. During fMRI scans, the IXT children and NCs were provided with static visual stimuli (to evoke sensory fusion) and dynamic visual stimuli (to evoke motor fusion and vergence eye movements) with binocular disparity. Brain activation in the relevant brain regions and clinical characteristics were evaluated. Group differences of brain activation and brain-behavior correlations were investigated. For dynamic and static visual disparity relative to no visual disparity, reduced brain activation in the right FEF and right inferior occipital gyrus (IOG), and increased brain activation in the left middle temporal gyrus complex (MT+) were found in the IXT children compared with NCs. Significant positive correlations between the fusional vergence amplitude and the brain activation values were found in the right FEF, right IPL, and left cerebellum in the NC group. Positive correlations between brain activation values and Newcastle Control Scores (NCS) were found in the left MT+ in the IXT group. For dynamic visual disparity relative to static visual disparity, reduced brain activation in the right middle occipital gyrus, left cerebellum, and bilateral IPL was found in the IXT children compared with NCs. Significant positive correlations between brain activation values and the fusional vergence amplitude were found in the right FEF and right cerebellum in the NC group. Negative correlations between brain activation values and NCS were found in the right middle occipital gyrus, right cerebellum, left IPL, and right FEF in the IXT group. These results suggest that the reduced brain activation in the right FEF, left IPL, and cerebellum may play an important role in the pathogenesis of IXT by influencing fusional vergence function. While the increased brain activation in the left MT+ may compensate for this dysfunction in IXT children.

Blur Representation in the Amblyopic Visual System Using Natural and Synthetic Images.

Purpose: Amblyopia is diagnosed as a reduced acuity in an otherwise healthy eye, which indicates that the deficit is not happening in the eye, but in the brain. One suspected mechanism explaining these deficits is an elevated amount of intrinsic blur in the amblyopic visual system compared to healthy observers. This "internally produced blur" can be estimated by the "equivalent intrinsic blur method", which measures blur discrimination thresholds while systematically increasing the external blur in the physical stimulus. Surprisingly, amblyopes do not exhibit elevated intrinsic blur when measured with an edge stimulus. Given the fundamental ways in which they differ, synthetic stimuli, such as edges, are likely to generate contrasting blur perception compared to natural stimuli, such as pictures. Because our visual system is presumably tuned to process natural stimuli, testing artificial stimuli only could result in performances that are not ecologically valid. Methods: We tested this hypothesis by measuring, for the first time, the perception of blur added to natural images in amblyopia and compared discrimination performance for natural images and synthetic edges in healthy and amblyopic groups. Results: Our results demonstrate that patients with amblyopia exhibit higher levels of intrinsic blur than control subjects when tested on natural images. This difference was not observed when using edges. Conclusions: Our results suggest that intrinsic blur is elevated in the visual system representing vision from the amblyopic eye and that distinct statistics of images can generate different blur perception.

Quantitative Analysis of Translatory Movements in Patients With Horizontal Strabismus.

Purpose: To investigate translatory movement during the lateral gaze in patients with horizontal strabismus using magnetic resonance imaging. Methods: Patients with esotropia or exotropia and normal controls underwent orbital magnetic resonance imaging during the central gaze and lateral gaze at 40°. The position of the static tissues was superimposed three-dimensionally for all gazes using a self-developed software, allowing the analysis of the net eyeball movement. Then, the eyeball centroid coordinates were extracted for each gaze, and the distance and direction of centroid movement from the central to lateral gaze were calculated. Results: The mean distance ± standard deviation of the centroid movement was 1.0 ± 0.5 mm during abduction in the exotropia group, which was significantly longer than that in the esotropia (0.6 ± 0.3 mm; P = 0.003) and control (0.7 ± 0.2 mm; P = 0.002) groups. Conversely, the centroid moved farther in the esotropia group (0.9 ± 0.3 mm) than the exotropia (0.6 ± 0.3 mm; P = 0.005) and control (0.7 ± 0.2 mm; P = 0.023) groups during adduction. Posterior translation during abduction was longer in the exotropia group (-0.8 ± 0.3 mm) compared with the esotropia (-0.5 ± 0.3 mm; P = 0.017) and control (-0.4 ± 0.3 mm; P = 0.001) groups, whereas that during adduction was longer in the esotropia group (-0.4 ± 0.4 mm) than the exotropia (-0.1 ± 0.2 mm; P = 0.033) and control (-0.1 ± 0.2 mm; P = 0.026) groups. Conclusions: During abduction, more translatory movement occurred in the exotropia group, whereas the centroid moved farther in the esotropia group during adduction. The translatory movement difference between both strabismus groups implies that there is a difference in biomechanics among the types of strabismus.

High Level of Inflammatory Cytokines in the Tears: A Bridge of Patients with Concomitant Exotropia and Dry Eye.

Concomitant exotropia have obvious symptoms of eye discomfort in adults, and the presence of ocular surface inflammation in patients may be important mediators between concomitant exotropia and dry eye. Oculus Keratograph eye comprehensive analyzer was performed to detect noninvasive tear break time, noninvasive tear height, and eye red index, while the ocular surface disease index and schirmer I testing were made. The levels of IL-6, IL-10, IL-17A, IL-12P70, INF-γ, and TNF-α were detected in tears in patients with concomitant exotropia and healthy controls matched by age and gender through the Simoa technology. IL-6 was significantly higher in patients with concomitant exotropia (4.683 ± 1.329) pg/mL than that in normal group (1.455 ± 0.391) pg/mL, p = 0.0304. TNF-α was also significantly higher in patients (0.2095 ± 0.0703) pg/mL than normal group (0.0513 ± 0.0149) pg/mL, p = 0.0397. The levels of inflammatory factors in strabismic patients vs. normal controls were as follows: IL-17A (0.1551 pg/mL︰0.0793 pg/mL), IL-10 (0.3358 pg/mL︰0.0513 pg/mL), IL-12p70 (0.0253 pg/mL︰0.0099 pg/mL), and INF-γ (0.0284 pg/mL︰0.009 pg/mL) were detected, and the median of them in concomitant strabismus was 1.96-6.55-fold as much as the control group. High levels of inflammatory cytokines in tears of patients with concomitant exotropia, which may be a potentially factor promoted the occurrence of dry eye in the patients with concomitant exotropia.

Improvement of binocular summation in intermittent exotropia following successful postoperative alignment.

To investigate the improvement of binocular summation (BiS) at high contrast (100%) and different low contrasts (10, 5 and 2.5%) in patients with intermittent exotropia (IXT) after successfully postoperative alignment. A total of 76 patients (aged 9-40 years) with IXT and poor control at distance before surgery were enrolled in this study. The postoperative deviations ranged between 4 PD esophoria to 10 PD exotropia in the primary position (at near and at distance) in all the enrolled patients. The follow-up visits were 2-3 months after the surgery. We analyzed preoperative and postoperative BiS and the proportions of patients with different BiS for the high contrast and the low contrasts. Binocular summation (BiS) was classified into three situations: binocular summation, equal and inbibition. The results of the distant random dots stereograph (RDS) were grouped into A, unable to recognize; B, moderate, 200″ ≤ RDS ≤ 400″ and C, good, RDS < 200″. Following the successful postoperative alignment, the proportion of patients with BiS were increased from 9.2 to 40.8%, 17.1 to 53.9%, 21.1 to 76.1% and 21.1 to 72.4% at 100%, 10%, 5% and 2.5% contrasts respectively. At 2.5% contrast, (1) more patients presented binocular summation in the groups B and C; (2) postoperative improvements of binocular visual acuity (BVA) in groups B (1.5 ± 1.03 lines) and C (1.57 ± 1.26 lines) were significantly different from the BVA in the group A (0.74 ± 1.00 line); and (3) in the group with central fusion, more patients presented BiS after surgery and the postoperative BVA improved by 1.43 ± 1.16 lines. Binocular summation for high contrast and different low contrasts can be improved in patients with IXT after successful surgical treatment. The improvement of BiS was associated with obtaining central fusion, recovering distant stereopsis and good alignment after the surgeries. The most significant improvement was shown at 2.5% contrast and was associated with good stereopsis and central fusion. The improvement of BiS, particularly at low contrast, has benefits for the daily activities in the real environment. BiS improvement could be used as a supplementary assessment of binocular function in patients with IXT before and after treatment.

Interocular Suppression in Primary Visual Cortex in Strabismus.

People with strabismus acquired during childhood do not experience diplopia (double vision). To investigate how perception of the duplicate image is suppressed, we raised two male monkeys with alternating exotropia by disinserting the medial rectus muscle in each eye at age four weeks. Once the animals were mature, they were brought to the laboratory and trained to fixate a small spot while recordings were made in primary visual cortex (V1). Drifting gratings were presented to the receptive fields of 500 single neurons for eight interleaved conditions: (1) right eye monocular; (2) left eye monocular; (3) right eye's field, right eye fixating; (4) right eye's field, left eye fixating; (5) left eye's field, right eye fixating; (6) left eye's field, left eye fixating; (7) both eyes' fields, right eye fixating; (8) both eyes' fields, left eye fixating. As expected, ocular dominance histograms showed a monocular bias compared with normal animals, but many cells could still be driven via both eyes. Overall, neuronal responses were not affected by switches in ocular fixation. Individual neurons exhibited binocular interactions, but mean population indices indicated no net interocular suppression or facilitation. Even neurons located in cortex with reduced cytochrome oxidase (CO) activity, representing portions of the nasal visual field where perception is suppressed during binocular viewing, showed no net inhibition. These data indicate that V1 neurons do not appear to reflect strabismic suppression and therefore the elimination of diplopia is likely to be mediated at a higher cortical level.SIGNIFICANCE STATEMENT In patients with strabismus, images fall on non-corresponding points in the two retinas. Only one image is perceived, because signals emanating from the other eye that convey the duplicate image are suppressed. The benefit is that diplopia is prevented, but the penalty is that the visual feedback required to adjust eye muscle tone to realign the globes is eliminated. Here, we report the first electrophysiological recordings from the primary visual cortex (V1) in awake monkeys raised with strabismus. The experiments were designed to reveal how perception of double images is avoided.

Clinical factors affecting the rate of exodrift after surgery in patients with basic intermittent exotropia.

We investigated the period of postoperative exodrift during follow-up and clinical factors that affect the rate of exodrift after surgery in the patients with intermittent exotropia (IXT). A retrospective review of medical records of patients with exodrift who underwent bilateral rectus recession for IXT was performed. Exodrift was defined as angle of deviation greater than 10 prism diopters (PD) at distance and near. The median survival period of postoperative exodrift was analyzed using Kaplan Meier survival analysis. The patients were divided into two groups according to the median period of postoperative exodrift (early and late group). The weighted Cox's proportional hazards regression analysis to investigate the risk factors that affect rate of postoperative exodrift was performed. A total of 108 patients was included. The preoperative angle of deviation at distance and near were 30.3 ± 7.2 PD and 29.5 ± 8.6 PD, respectively. The median survival period of postoperative exodrift was 24 months (range, 6-48 months).The angle of deviation at postoperative day 1 in early and late group were - 3.8 ± 5.5 PD (range, - 16-8 PD) and - 7.7 ± 4.6 PD (range, - 16-4 PD) (p < 0.01). Minus value means esodeviation. In regression analysis, the angle of deviation at postoperative day 1 was the significantly related with rate of exodrift (p < 0.01). The median period of exodrift after surgery was 24 months, angle of deviation at postoperative day 1 could affect the rate of exodrift in patients with IXT.

Efficacy of bilateral lateral rectus recession versus unilateral recession and resection for basic-type intermittent exotropia: a meta-analysis.

PURPOSE: To investigate the efficacy of bilateral lateral rectus recession (BLR) versus unilateral recession and resection (RR) for the treatment of patients with basic-type intermittent exotropia (IXT). METHODS: We systematically searched the EMBASE, PubMed, Web of Science and Cochrane Library databases for relevant studies published before April 2020 with no language restrictions. Related studies meeting the eligibility criteria were included. The primary outcomes were success rate and mean postoperative deviation. Odds ratios (ORs) and weighted mean differences (MDs) with 95% confidence intervals (CIs) were calculated. RESULTS: From 1243 screened articles, a total of 10 studies involving 967 patients were included in the analysis. No differences were observed in success rates between the BLR and RR groups at 1-day to 1-week postoperatively (OR: 0.9, 95% CI: 0.53 to 1.53, p = 0.69), or at 6-month postoperatively (OR: 1.11, 95% CI: 0.59 to 2.11, p = 0.74), or at the last follow-up visit (OR: 0.76, 95% CI: 0.44 to 1.34, p = 0.34). The unsatisfactory effects (the overcorrection and undercorrection rates) between the two groups were comparable. In addition, there were no significant differences between the two groups in postoperative deviation at 1-day to 1-week postoperatively (MD: 0.03, 95% CI: -1.32 to 1.27, p = 0.97), or at 6-month postoperatively (MD: 1.42, 95% CI: -0.43 to 3.27, p = 0.13) or at the last follow-up visit (MD: 0.29, 95% CI: -1.39 to 1.97, p = 0.74). CONCLUSION: This meta-analysis provides evidence that both the BLR and RR procedures have similar efficacy for the treatment of basic-type IXT.

Effect of age on reoperation rate in children undergoing exotropia surgery.

PURPOSE: To determine the effect of age on the reoperation rate in children undergoing exotropia surgery. METHODS: This was a population-based retrospective cohort study using claims data that included children ≤ 12 years who had undergone exotropia surgery as the first strabismus operation and had ≥ 3 years of continuous enrolment were selected from the Optum de-identified Clinformatics Data Mart Database (2003-2019). Patient age at the first exotropia surgery was grouped into three categories; 0-3, 4-6, and 7-12 years. We assessed the sex, race, age, surgical methods, continuous enrolment period after the first surgery, and the time between the first surgery and reoperation. Cox regression analysis was used to estimate the risk of reoperation at different ages. The hazard ratio of reoperation in children undergoing exotropia surgery according to the age at the first exotropia surgery. RESULTS: Among 2015 children, 312 (15.5%) underwent one or more reoperations. A reoperation was more often performed for recurrent exotropia (n = 231) than for consecutive esotropia (n = 81). The time between the first surgery and reoperation was shorter for reoperation for consecutive esotropia (376 days) than for recurrent exotropia (672 days) (p < 0.001). Younger children showed a higher reoperation hazard ratio than older children (p < 0.001). In reoperation for consecutive esotropia, the patients aged 0-3 years showed a high hazard ratio (2.82; 95% CI, 1.59-5.01). CONCLUSION: Children undergoing exotropia surgery at a younger age have a higher reoperation rate than those undergoing surgery at an older age.

Spectacle Decentration to Augment Over-minus Therapy in Cases with Intermittent Exotropia.

Purpose: To evaluate the adding effect of inward decentration of concave spectacle lenses (adding a prismatic effect) on angle control in cases with distance intermittent exotropia (IXT) receiving over-minus therapy.Methods: Patients with myopia with IXT angles ≤25 and a Newcastle score (NCS) ≥5 were included. Patients were randomised into two groups. Group 1 received over-minus therapy. Group 2 received over-minus therapy with inward decentration of spectacle glasses to add a base out prism effect equal to one-third of the distance angle of deviation. Success was measured as the percentage of orthotropic cases or those with orthophoria or IXT with improved NCS ≤ 3 and tolerant to treatment. Patients were evaluated 3 months after initial treatment, 3 months after partial weaning and 18 months after complete weaning.Results: Sixty-four patients were included, with 32 in each group. The success rates of group 1 were 65.6%, 37.5%, and 31.3%, in group 2, the rates were 75%, 65.6%, and 65.6% for orthotropic cases or those with orthophoria or IXT with improved NCS ≤ 3, respectively. Moreover, NCS significantly improved in group 2 till last visit.Conclusion: Adding decentration to over-minus therapy can result in better control of small angle IXT and could be considered as a non-invasive and reversible therapy.

Clinical Usefulness of a Computerized Vision Chart for Distance Stereoacuity Assessment in Children with Intermittent Exotropia.

INTRODUCTION: The aim of this study is to evaluate distance stereoacuity in children with intermittent exotropia (IXT) using a computerized vision chart (CVC), to compare the results to the normal subjects, and to determine if any correlation between stereoacuity and IXT severity exits. METHODS: A prospective case-control study was conducted including 24 children with IXT and 25 age-matched normal subjects. The mean age was 8.9 ± 4.5 in IXT group and 9.4 ± 4.2 in control group. The majority of patients (n = 17) had basic type IXT. Full ophthalmic examinations, deviations and stereoacuity tests were evaluated. Stereoacuity was measured with the CVC for distance stereoacuity and Randot stereotest book for near stereoacuity. Level of fusional control in patients with IXT was assessed using Newcastle Control Score (NCS). Seven of the patients with IXT were also reevaluated postoperatively. RESULTS: Near stereoacuity was good in both IXT and control groups, and there was no significant difference between groups. There was a poor correlation between near stereoacuity and NCS (rs = 0.15, p = .48). Distance stereoacuity in the IXT group was significantly reduced compared to controls (p = .004). There was a positive correlation between distance stereoacuity values and NCS in patients with IXT (rs = 0.73, p < .001). CONCLUSION: Diminished distance stereoacuity in children with IXT can be detected with the CVC and this test may be useful for deciding the timing of surgical intervention and postoperative evaluation.

Bilateral Occlusion Reduces the Ocular Deviation in Intermittent Exotropia.

Purpose: The most common form of strabismus, intermittent exotropia, is thought to become manifest when the drive to fuse is overcome by excessive divergent muscle tone. This principle is tested by examining the alignment of the eyes in the absence of vision. We compare the ocular deviation in patients with intermittent exotropia under conditions of monocular versus binocular occlusion. Methods: This prospective study of a patient cohort referred to our laboratory enrolled 18 patients with typical findings of well-controlled intermittent exotropia. Eye positions were recorded with video eye trackers while patients looked at a fixation spot at a distance of 57 cm. One eye was occluded, and the resulting ocular deviation was measured. Both eyes were then occluded, and the ocular deviation was re-measured. Results: The majority of patients (11/18) had a smaller deviation when both eyes were covered. Occlusion of one eye resulted in a mean exotropia of 13.5° ± 4.7°. Occlusion of both eyes reduced the mean exotropia to 6.0° ± 6.5° (paired t-test, P < 0.001), corresponding to a 56% reduction in the ocular deviation. This reduction persisted during prolonged bilateral occlusion but reversed as soon as vision was restored. Conclusions: Bilateral occlusion reveals a fixation-free state of alignment that is different from orthotropia and usually less than the exotropia that occurs spontaneously during binocular viewing. This finding demonstrates that the deviation angle in patients with intermittent exotropia is actively mediated by visual feedback, which the fixating eye is capable of providing alone.

Comparativa del control postural entre niños estrábicos y no estrábicos / Comparison of postural control between strabismic and non-strabismic children

OBJETIVO: Comparar el control postural de niños estrábicos frente a niños sin estrabismo. MATERIAL Y MÉTODOS: Cohortes transversales. Se incluyeron un total de 171 niños: 73 niños con endotropia, 24 con exotropia y 74 controles. El control postural fue explorado mediante una plataforma dinamométrica en bipedestación, en varias condiciones: ojos abiertos y cerrados, fijación de mirada cercana y lejana; y sobre suelo duro y gomaespuma. Se estudiaron como variables: el área, la velocidad media, las longitudes en el eje X e Y del desplazamiento del centro de presión. RESULTADOS: Los niños con endotropia y exotropia presentaron valores de velocidad media, longitud X e Y significativamente mayores frente a los controles en el examen de ojos abiertos, distancia de fijación lejana y sobre suelo de gomaespuma; con ojos abiertos, sobre suelo duro y distancia lejana, los valores de las exotropias fueron mayores que los de endotropias y controles. Con ojos cerrados, no hubo diferencias entre los 3 grupos en todas condiciones de exploración descritas, pero sus valores empeoraban frente a sus respectivos con ojos abiertos. CONCLUSIONES: Los niños estrábicos presentaron un peor control postural que los niños no estrábicos. Todos los niños se mostraron más inestables con ojos cerrados frente a con ojos abiertos lo que demuestra que, tanto para estrábicos como no estrábicos, la visión tiene un papel relevante en la estabilidad postural

OBJECTIVE: To compare the postural control of children with strabismus versus non-strabismus children. MATERIAL AND METHODS: Cross-sectional cohort study with a total of 171 children, including 73 children with esotropia, 24 with exotropia, and 74 controls. Postural control was determined using a dynamometric platform in a standing position in various conditions: eyes open and eyes closed, near and gaze fixation, and with and without foam pad. The studied variables were the area, the mean speed, and the lengths in the X and Y axis of the centre of pressure displacement. RESULTS: Children with esotropia and exotropia had significantly higher mean values (speed, lengths of X and Y) compared to controls. In the open-eye, far distance fixation, and on foam pad, as well as under exam conditions; with eyes open, without foam pad, and far distance fixation, the exotropia values were higher than those of endotropia and controls. With eyes closed, there were no differences between the 3 groups under the described examination conditions, but their values were worse compared to their respective ones with eyes open. CONCLUSIONS: The children with strabismus had a worse postural control than the non-strabismus ones. All of the them appeared to be more unstable with eyes closed than with eyes open, which demonstrates that vision plays an important relevant role in postural stability in both strabismus and non-strabismus children

Asymmetric superior oblique split Z-tendon lengthening for face turn in bilateral asymmetric superior oblique overaction and exotropia.

INTRODUCTION: The aim was to evaluate the effectiveness of the procedure of the superior oblique split Z-tendon lengthening to collapse A pattern and treat face turn in a cohort of patients with both incomitant intermittent exotropia and a vertical deviation associated with a bilateral asymmetric superior oblique overaction. METHODS: We retrospectively reviewed the clinical records of patients with facial turn associated with intermittent exotropia and bilateral asymmetric superior oblique overaction, who underwent superior oblique muscle split tendon lengthening and concurrent horizontal surgery between 2009 and 2017. RESULTS: A total of eight patients met the inclusion criteria. The preoperative average face turn was 26.8° (range, 20°-5°), and it significantly improved to 5.4° (range, 2°-8°) (p < 0.05). All the patients showed an improvement in the face turn with neutralization of the vertical deviation. The vertical deviation in the right gaze for the patient with a right turn and the left gaze in patients with left turn improved significantly (values of p < 0.05). CONCLUSION: The superior oblique split Z-tendon lengthening was an effective procedure to collapse the A pattern and the treatment of the face turn in a cohort of patients with both incomitant intermittent exotropia and a vertical deviation associated with a bilateral asymmetric superior oblique muscle overaction with less complications, and less varying results.

Medial Rectus Advancement for Secondary Exotropia.

PURPOSE: To determine the preoperative characteristics and surgical results after medial rectus advancement in patients with secondary exotropia. DESIGN: Retrospective, interventional case series. METHODS: Setting: Tertiary Care University Medical Center. PatientPopulation: 221 patients with a diagnosis of secondary exotropia who underwent medial rectus advancement surgery by a single surgeon. OBSERVATION: Preoperative demographics, exodeviation and motility, intraoperative findings, and postoperative results were recorded. MainOutcomeMeasure: Success of surgery, defined as Esotropia <15 prism diopters (pd) at postoperative week 1, or any deviation of <8 pd at postoperative month 2 (POM2). RESULTS: A total of 98 patients underwent unilateral medial rectus advancement (UMRadv), 89 underwent UMRadv with lateral rectus recession (LRc), and 34 underwent bilateral medial rectus advancement (BMRadv). POM2 success rates were 66.7% in UMRadv patients, 62.1% in UMRadv + LRc, and 56% in BMRadv. A total of 117 patients had preoperative adduction deficits, which were significantly associated with the finding of an intraoperative stretched scar (P < .001). Larger preoperative duction deficits were associated with larger stretched scars (P < .001). At POM2, the mean effect of surgery (pd of correction/mm) was 2.3 ± 1.4 pd/mm for UMRadv, 2.5 ± 0.8 pd/mm for UMRadv + LRc, and 2.8 ± 1.1 pd/mm for BMRadv. Patients with a stretched scar had significantly less correction per millimeter (2.2 ± 1.2 pd/mm) compared with those without (2.6 ± 1.2 pd/mm, P < .001). A total of 38.6% of patients experienced exodrift greater than 10 pd. Exodrift was significantly larger in the BMRadv group (P < .005). DISCUSSION: These results provide guidance for surgical correction based on preoperative deviation and ductions. Adduction deficits indicate a stretched scar, which must be treated with resection and advancement of the medial rectus. A larger amount of surgery is needed in patients with a stretched scar. Exodrift is common, and therefore aiming for approximately 10 pd of overcorrection at postoperative week 1 can improve final outcomes. CONCLUSION: Medial rectus advancement results in successful surgical results at POM2 for secondary exotropia.

Maintenance of normal fusion in intermittent exotropia.

PURPOSE: To evaluate the reliability of the Bagolini filter bar and striated lenses for measuring the fusion maintenance score, which is the ability of participants with intermittent exotropia to maintain normal sensorimotor fusion. METHODS: Thirty-two Chinese participants aged 7-20 years with intermittent exotropia (excluding the convergence insufficiency type) were enrolled in this prospective study. At the eligibility screening, visual acuity, cover test and assessment of the office control score were performed. At study visit 1, eligible participants underwent negative and positive fusional vergence tests at far and near, eye dominance test and the fusion maintenance test. All eligible participants returned for study visit 2 on the same day (2-4 h later) and the testing was repeated. The primary outcome measure was the intra-class correlation coefficient of the fusion maintenance score between the two study visits. RESULTS: The intra-class correlation coefficient of the fusion maintenance score was 0.84, indicating good reliability. There was no significant difference (mean difference = 0.05, p = 0.95) between the fusion maintenance scores for the first (5.62) and second study visits (5.57). The coefficient of repeatability and the smallest detectable change for the fusion maintenance scores were 7.6 and 6.3, respectively. The fusion maintenance score was significantly associated with the distance (Spearman correlation -0.57, p < 0.001) and near (Spearman correlation -0.4, p = 0.02) office control scores. CONCLUSION: These data demonstrate that the fusion maintenance score is a reliable tool to evaluate sensorimotor fusion in intermittent exotropia. These results suggest that the fusion maintenance score may be a useful outcome measure in future clinical trials to evaluate the effectiveness of treatments for intermittent exotropia.

The Study of Perceptual Eye Position Examination and Visual Perceptual Training in Postoperative Intermittent Exotropes.

The aim of this study was to investigate perceptual eye position (PEP) and to evaluate the effect of dichoptic visual perceptual training in postoperative intermittent exotropia [X(T)]. We enrolled 30 non-strabismus children (control group) and 54 postoperative X(T) children [divided into training group (33 patients) and non-training group (21 patients)]. All subjects received measurements of PEP, and the postoperative X(T) children were measured both in the third postoperative day and the third postoperative month. All patients in training group received 3-month dichoptic visual perceptual training based on a unique virtual reality platform. The results showed that the postoperative X(T) children with normal eye position still had an abnormal PEP. After a period of visual perceptual training, the PEP pixels in postoperative children dramatically decreased. The results revealed that PEP could evaluate fixation disparity and binocular visual function perceptively and precisely, and the dichoptic visual perceptive training may rebuild binocular visual function.

Assessing Variability of Control Within a Single Day in Intermittent Exotropia.

PURPOSE: To assess intra-individual hour-to-hour variability of control in intermittent exotropia using a simple office scale: Look And Cover, then Ten seconds of Observation Scale for Exotropia (LACTOSE). METHODS: In this prospective cross-sectional study, the degree of control for distance and near was measured using the LACTOSE, a 5-point scale ranging from 0 to 4. A single investigator performed multiple measurements of the control of each patient with at least an hour interval between measurements. RESULTS: Of the 95 patients with intermittent exotropia enrolled, 66 (69.5%) were assessed two times and 29 (30.5%) were assessed three times for their control. Most patients had consistent control scores across multiple assessments for distance (n = 63, 66.3%) and near (n = 70, 73.7%). Forty-five (47.4%) patients demonstrated variable control for either distance or near, mostly (n = 27, 60.0%) showing a one-step difference. None presented with more than a two-step difference in the control score on repeated measurements. An initial LACTOSE score of 4 (very poor control) or 1 (very good control) remained unchanged in subsequent assessments for both distance (P = .049) and near (P < .001). CONCLUSIONS: One-third of patients with intermittent exotropia showed variable control scores even during a single day across multiple measurements using the LACTOSE scale. Those who showed consistent control had very good or very poor control, whereas those with variable control had not had very good or very poor control on their initial LACTOSE measurements. [J Pediatr Ophthalmol Strabismus. 2020;57(6):378-383.].