Horizontal Rectus Research Articles

The long-term outcomes of the Anderson-Kestenbaum procedure.

Nystagmus is an involuntary, conjugated, rhythmic movement of the eye that can be idiopathic or secondary to ocular or neurologic pathologies. Patients with nystagmus often have a position of gaze in which their symptoms are dampened or absent, referred to as the "null zone." The Anderson-Kestenbaum procedure is a bilateral recess-resect procedure of the four horizontal rectus muscles which aims to bring the null position into the primary gaze. This study aims to further elucidate long-term outcomes and factors associated with optimal postoperative outcomes. Patients with a diagnosis of nystagmus and a surgical code for strabismus between June 1990 and August 2017 were considered for inclusion in the study. Patients were included if they had undergone the Anderson-Kestenbaum procedure and had follow-up lasting at least 24 months post-operatively. Data collected included demographic information, characteristics of the nystagmus, underlying etiology of nystagmus, and pre-and post-operative measurements. 25 patients were included. At their last recorded follow-up, 44% of patients achieved an optimal surgical outcome -an abnormal head position of 10 degrees or less. 88% of patients showed an overall improvement in their head posture at the last follow-up. The absence of an abnormal head position at the visit closest to 24 months post-operatively was found to be significantly associated with the lack of a significant head position at the last follow-up visit. Optimal surgical outcomes were not significantly associated with the underlying diagnosis, the direction of the abnormal head position, or the type of nystagmus. The relatively long follow-up of this cohort allows this study to further elucidate the long-term outcomes of the Anderson-Kestenbaum procedure. Overall, our results suggest that although improvement in head position post-operatively is likely, it is still expected that many patients will have a residual abnormal head position after the procedure. The results of this study are helpful in counseling patients, especially knowing that if they do not have a significant head position at 24 months follow-up, they are unlikely to develop one. However, due to the small sample size, larger cohorts and more standardized follow-up may provide further insight into the procedure's outcomes.

Changes in retinal and choroidal blood flow after one or two horizontal rectus muscle surgeries by optical coherence tomography angiography

Purpose To evaluate the retinal and choroidal microvasculature after one or two horizontal rectus muscle surgeries in strabismus patients using swept-source optical coherence tomography angiography (SS-OCTA). Methods 30 eyes of 26 patients who underwent horizontal rectus muscle surgery were included in this study. Group A, A’ and Group B , B’ respectively consisted preoperative and postoperative measurements of patients who underwent one or two horizontal rectus muscle surgeries. We analyzed the vessel density (VD) of the superficial vascular complex (SVC), the deep vascular complex (DVC), the choriocapillary layer (CC), choroidal vascular index (CVI), choroidal thickness (T-Ch) and retinal nerve fiber layer thickness (T-RNFL) preoperatively, and one week postoperatively. Results Only in the nasal sector of the perifoveal zone, the VD in SVC demonstrated a significant increase in Group A’ (p = 0.027). There was a statistically significant difference in the VD changes of SVC between Group A and Group B (p = 0.043). The VD in DVC did not change significantly in the whole macular compared with the preoperative. Moreover, in both Group A’ and Group B’, the VD in CC showed a reduction in a single sector of the parafoveal area (p < 0.05). Group A’ have increased CVI in the nasal sector of the perifoveal region (p = 0.008). In addition, the T-Ch increase in the perifoveal region was more significant in Group B’ than in Group A’ (p < 0.05). Group A’ showed statistically significant decreases in T-RNFL in the foveal and parafoveal regions (p < 0.05). Conclusion This study revealed that the increase in choroidal thickness was more significant after two rectus muscle surgery. In addition, there were microvascular changes in sectional macular regions after strabismus surgery. OCTA is an excellent way to study the impact of strabismus surgery on the macular structure and blood flow.

Comparison of anterior segment optical coherence tomography and ultrasound biomicroscopy in localizing horizontal rectus muscle insertions.

To evaluate the viability and precision of measuring the distance from the limbus to extraocular muscle insertion using anterior segment optical coherence tomography (AS-OCT) and panoramic ultrasound biomicroscopy (UBM) before and after strabismus surgery. We recruited primary strabismus patients and measured the limbus-insertion distance by AS-OCT and UBM preoperatively, 2 weeks, and 1, 3, and 6 months postoperatively. Values were also measured using callipers intraoperatively before and after the planned procedures. Preoperative AS-OCT and UBM values were compared to intraoperative calliper measurements as the gold standard. Postoperative AS-OCT and UBM values were compared to the new postoperative limbus-insertion distance. The limit of agreement deemed clinically acceptable was defined as 1 mm. A total of 85 horizontal muscles of 40 patients, including 48 lateral rectus muscles and 37 medial rectus muscles, were analysed. Primary muscles could be successfully detected by AS-OCT (95%) and UBM (100%). At 2 weeks and 1, 3, and 6 months postoperatively, the new rectus muscle attachment site detection rate by AS-OCT was 6%, 32%, 80%, and 89%, respectively, and that by UBM was 24%, 60%, 85%, and 93%, respectively. The Bland-Altman plots revealed better consistency in pairs of AS-OCT, UBM, and calliper measurements of primary muscles than postoperative muscles. For primary muscles, 89% of AS-OCT measurements fell within the permissible range of surgical measurements (1 mm), but this dropped to 67% at 6 months postoperatively (P < 0.001). The accuracy of UBM measurements of primary muscles was 81%, and this decreased to 59% at 6 months postoperatively (P = 0.001). AS-OCT and UBM performed well in terms of imaging primary horizontal rectus muscles, but showed decreased accuracy and reproducibility in postoperative muscle measures.

Magnetic Resonance Imaging Findings in Patients With Duane Retraction Syndrome.

Duane retraction syndrome (DRS) is known to relate to the absence of the abducens nucleus, with abnormal innervation of the lateral rectus (LR) muscle by branchesof the oculomotor nerve (CN III). The purposes of this study were to investigate the morphological characteristics of the oculomotor nerve (CN III), the abducens nerve (CN VI), and the extraocular muscles in patients with clinically diagnosed Duane retraction syndrome (DRS) using MRI. In addition, we assessed the association between ocular motility, horizontal rectus muscle volumes, and CN III/VI in patients with Duane retraction syndrome (DRS). The study comprised 20 orthotropic control subjects (40 eyes) and 42 patients with Duane syndrome (48 eyes), including 20 patients with DRS Type I (24 eyes), 5 patients with DRS Type II (6 eyes), and 17 patients with DRS Type III (18 eyes). Three-dimensional (3D) T1/2 images of the brainstem and orbit were obtained to visualize the cranial nerves, especially the abducens (VI) and oculomotor (III) nerves, as well as extraocular muscles. Based on the clinical classification, among 42 patients, MRI showed that the abducens nerves (CN VI) on the affected side were absent in 24 of 24 eyes (100%; 20 patients) with Type I DRS and in 16 of 18 eyes (88%; 16 patients) with Type III DRS. However, CN VI was observed in 6 of 6 eyes (100%; 5 patients) with Type II DRS and in 2 of 18 eyes (11%) with Type III DRS. CN III was observed in all patients. The oculomotor nerves on the affected side were thicker than those on the nonaffected contralateral side in DRS Type I ( P < 0.05) and Type III ( P < 0.05), but not in DRS Type II. Smaller LR and larger MR volumes were shown in the affected eye than that in the nonaffected eye in DRS Types I and III. Based on the presence or absence of CN VI, there was a tendency for thicker oculomotor nerves in the affected eye than in the nonaffected eye in the absence groups ( P < 0.05). However, no significant difference was found in the present group. In the CN VI absence groups, similar results were found in the affected eyes than in the nonaffected eyes as in DRS Types I and III. In addition, the presence of CN VI was correlated with better abduction ( P = 0.008). The LR and MR volumes have positive correlations with the oculomotor nerve diameter in the affected eye. However, there was no correlation between the range of adduction/abduction and the LR/MR ratio in patients with or without an abducens nerve. Different types of DRS have different characteristic appearances of CN VI and CN III on MRI. Horizontal rectus muscles have morphological changes to adapt to dysinnervation of CN VI and aberrant innervation of CN III. Thus, these neuroimaging findings may provide a new diagnostic criterion for the classification of DRS, improving the comprehension of the physiopathogenics of this disease.

Evaluation of the effects of strabismus surgery on corneal backward light scattering

BackgroundInvestigation of the effects of conventional strabismus surgeries on corneal densitometry (CD). MethodsPatients who had strabismus surgery between May 2022 and July 2022 were included in the study. CD software with a Pentacam device was used to determine corneal backward light scattering. CD data were analysed preoperatively and 1 month postoperatively. Patients were classified as those who had single muscle and two-muscle surgery. ResultsThe study included 33 eyes of 28 patients. The mean age of the patients was 20.51 ± 8.22 (5–35) years. Of the eyes, 19 underwent single muscle recession surgery. Two-muscle surgeries (recession and resection combination) were performed in 14 eyes. In the 1st month postoperative, the mean CD value decreased statistically significantly only in the total cornea apical 0–2 mm zone among the layers examined (p = 0.039). There was no significant change in the other layers (p > 0.05 for all). Single-muscle and two-muscle surgery groups were similar in the amount of CD reduction, except for one layer. ConclusionsCD did not change in most of the corneal layers examined in the first month postoperatively. Single muscle and two-muscle horizontal rectus surgeries did not impair corneal clarity in the postoperative 1st month.

Inferior displacement of the lateral rectus muscle insertion in exotropia with mild V-pattern or vertical deviation.

To describe clinical features and intraoperative findings of the patients with exotropia who presented mild V-pattern or vertical deviation, and to investigate the surgical outcomes of anatomical relocation of inferiorly displaced lateral rectus (LR) muscle insertion. Detailed ophthalmological evaluations were obtained in 42 consecutive patients, and the horizontal rectus muscle insertions were detected intraoperatively. The displaced insertion of LR muscle was corrected accompanied with classic recession-resection procedure. The inferiorly displaced LR muscle insertions were detected in 19 patients (Group A), while the remaining 23 patients (Group B) had normal insertions. The mean distance of displaced insertion from the normal position was 2.92 ± 1.05 mm (range: 1.0-4.0). Mild V-pattern was more common in Group A (78.9%, 15/19) than Group B (47.8%, 11/23), and the magnitude of V-pattern in Group A (6.16 ± 3.91 PD) was also greater than Group B (3.43 ± 3.92 PD). The fundus extorsions of the affected eyes (9.68 ± 4.77 °) were greater than the contralateral eyes (5.91 ± 5.82 °) in Group A. At the 2 months follow-up, mild V-pattern and mild vertical deviation were corrected by upward transposition. The significant correlations were identified between the pre-operative misalignments and the amounts of misalignments correction. Nearly half of the cases with mild V-pattern or vertical deviation resulted from the inferiorly displaced LR muscle insertion, so the intraoperative exploration of the LR muscle insertion is strongly suggested. Upward transposition may effectively correct both the mild V-pattern and vertical deviation.

Evaluation of Macular Thickness Changes Following Large Horizontal Rectus Muscle Recession: A Prospective Cohort Study.

Aim The aim of the study was to evaluate the long-termeffect of large horizontal rectus muscle recession on macula thickness using spectral domain optical coherence tomography (SD-OCT). Material and methods Forty-twochildren were included in the study. The intervention groups were the medial rectus (MR) group (=20 eyes ) and the lateral rectus (LR) group (=22 eyes), including the eyes that underwent large medial and lateral rectus muscle recession, respectively. The control group included the fellow 42 unoperated eyes of the same children. Each eye was scanned using Topcon Maestro2 OCT-Angiography (OCTA; Topcon, Tokyo, Japan) preoperatively and then two months following surgery. A paired t-test was used to compare the mean difference in macular thickness between the intervention and control groups using the statistical program R (R Foundation for Statistical Computing, Vienna, Austria). Results The mean change in central, parafoveal, and perifoveal macular thickness of the intervention group was not statistically significant. Conclusion The long-term changes in macular thickness, as evaluated using SD-OCT both for the central and peripheral regions of the fovea, following large horizontal rectus muscle recession surgery, are not statistically significant.

How to reduce conjunctival cyst formation after strabismus surgery?

ABSTRACT Purpose To determine our rate of conjunctival cyst developing after strabismus surgery and to minimize its formation Materials and Methods The data of 4026 eyes of 2662 patients were included in our retrospective analysis of, those that underwent strabismus surgery at the Beyoğlu Eye Training and Research Hospital Strabismus Unit between 2015 and 2021. Clinical characteristics and follow-up data of patients were recorded together with age, sex, and operation type. All patients were examined postoperatively on 1st day, 1st month and 6th month. Results The mean age of the patients was 15.66 ± 11.81 (1–59 years). While two eyes were operated on in 1494 patients, one eye was operated on in 1168 patients. The surgeries performed were recession and/or resection of the horizontal and vertical rectus muscles and inferior and superior oblique procedures. The conjunctival cyst was detected in 11 patients postoperatively between 20 days and 8 months. The cyst was detected on the nasal side in 7 cases and temporal in 4. Conclusion Conjunctival cyst is a rare complication after strabismus surgery and it is thought to be caused by a proliferation of the conjunctival epithelium. In addition to proper closure of the conjunctiva, attention to personal hygiene, avoidance of contacts that may increase suture contamination, and attention to the fact that the operation period is not long are actions that can help prevent conjunctival cyst formation.

Cirugía monocular de 4 músculos extraoculares para la exotropía monocular de gran ángulo

IntroductionRecurrent exotropia is common following surgery for monocular large angle constant sensory exotropia. Surgery is usually limited to operations on the affected eye. Simultaneous oblique weakening surgery may enhance the effect of the horizontal rectus muscles surgery by decreasing the abducting forces. We report the results of simultaneous oblique muscle weakening procedures combined with ipsilateral horizontal rectus muscle surgery constant monocular exotropia greater than 35 prism diopters (PD). MethodsRetrospective case series of patients who underwent unilateral lateral rectus recession combined with medial rectus muscle resection and simultaneous weakening of both ipsilateral oblique muscles. Primary outcome measure was ocular alignment in primary position. ResultsTwelve eyes of 12 patients were included. The mean preoperative exotropia improved from 57.9±15.1 (range 35–80; median 60PD) to 3.3±5.5 (range 0–16; median 0PD) postoperatively (p<0.005). Two (66%) patients with a pre-existing vertical deviation had resolution of their vertical misalignment postoperatively. At the last postoperative follow up 92% of the patients had an exodeviation of 10PD or less (range 0–16PD median 0PD), and 7 (58%) measured near and distance orthotropia. Postoperative abduction measured −0.6±1 (0 to −3) and adduction −0.4±0.7 (0 to −2). ConclusionWeakening the ipsilateral oblique muscles may enhance the effect of the horizontal rectus muscles surgery by decreasing the abducting vectorial forces when operating for a large angle monocular exotropia. As an additional potential advantage, oblique muscle surgery may be used simultaneously to address associated vertical deviations.

Unilateral four muscle surgery for extra-large monocular exotropia

IntroductionRecurrent exotropia is common following surgery for monocular large angle constant sensory exotropia. Surgery is usually limited to operations on the affected eye. Simultaneous oblique weakening surgery may enhance the effect of the horizontal rectus muscles surgery by decreasing the abducting forces. We report the results of simultaneous oblique muscle weakening procedures combined with ipsilateral horizontal rectus muscle surgery constant monocular exotropia greater than 35 prism diopters (PD). MethodsRetrospective case series of patients who underwent unilateral lateral rectus recession combined with medial rectus muscle resection and simultaneous weakening of both ipsilateral oblique muscles. Primary outcome measure was ocular alignment in primary position. ResultsTwelve eyes of 12 patients were included. The mean preoperative exotropia improved from 57.9 ± 15.1 (range 35–80; median 60 PD) to 3.3 ± 5.5 (range 0–16; median 0 PD) postoperatively (p < 0.005). Two of 3 patients with a pre-existing vertical deviation had resolution of their vertical misalignment postoperatively. At the last postoperative follow up 92% of the patients had an exodeviation of 10 PD or less (range 0–16 PD median 0 PD), and 7 (58%) measured near and distance orthotropia. Postoperative abduction measured −0.6 ± 1 (0 to −3) and adduction −0.4 ± 0.7 (0 to −2). ConclusionWeakening the ipsilateral oblique muscles may enhance the effect of the horizontal rectus muscles surgery by decreasing the abducting vectorial forces when operating for a large angle monocular exotropia. As an additional potential advantage, oblique muscle surgery may be used simultaneously to address associated vertical deviations.

A Comparative Study of Surgical Outcomes between the Adjustable Suture Technique and Conventional Technique in Strabismus Surgery

Objective: To compare the success rate between adjustable suture technique and conventional technique in rectus muscle surgery. Materials and Methods: The present study was a retrospective review of patients aged 10 and above underwent rectus muscle surgery between 2010 and 2018. Patients were classified into two groups according to the surgical techniques, the adjustable group and the conventional group. Preoperative and postoperative orthoptic evaluation including angle of deviation, sensory outcomes, and reoperation rate were collected. The primary outcome was surgical success rate at two years postoperatively, with success defined as ocular alignment within 10 prism diopters (PD) for horizontal rectus muscle surgery or within 5 PD for vertical rectus muscle surgery. The secondary outcome was reoperation rate and binocular functions improvement two years post-operation. Results: One hundred fifteen cases in the adjustable group and 90 in the conventional group were identified. Patients in the adjustable group had a higher success rate achieving the target angle after six months, one year, and two years post-operation compared to the conventional group at 77.4% versus 70% (p=0.23), 73.9% versus 65.6% (p=0.19), and 72.2% versus 60% (p=0.066), respectively, but there was no statistically significant difference. Sensory improvement was seen in 43.4% of patients in the conventional group and 42.6% in the adjustable group (p=0.54). Median stereopsis improvement was seen in both groups at 80 to 45 seconds of arc in the adjustable group and 100 to 60 seconds of arc in the conventional group (p=0.67). The reoperation rate was 18.9% in the conventional group and 19.1% in the adjustable group (p=0.97). Conclusion: The adjustable suture technique presented a superior success rate compared to conventional technique though there was no statistically significant difference. A longer follow-up period and larger sample size might be needed to demonstrate statistically significant difference between the two techniques. No significant difference in binocular functions, sensory improvement, or reoperation rate was seen in the present study. Keywords: Strabismus surgery; Adjustable suture; Conventional suture; Surgical outcome

Observation on the curative effect of horizontal rectus transposition combining recess-resect treatment on monocular elevation deficiency with horizontal strabismus.

To explore the clinical effect of horizontal rectus transposition combining recess and resect treatment on monocular elevation deficiency (MED) with horizontal strabismus. Ten patients (10 eyes) scheduled to undergo horizontal rectus transposition combining recess-resect surgery to treat MED with horizontal strabismus in the ME Department of Ophthalmology of the First Affiliated Hospital of Guangxi Medical University between July 2016 and February 2022 were included in the study. The degree of vertical and horizontal prism strabismus, the grading of upper movement of the paralyzed eye, and the improvement of binocular vision were evaluated before and after the surgery. Horizontal rectus transposition combined with recess and resect treatment was used to treat 10 patients with MED combined with horizontal strabismus. A good curative effect was seen in eight patients. The differences in the degree of vertical strabismus, the degree of horizontal strabismus, and the movement function of the paretic eyes before and after surgery were significantly different (all P < 0.05). The binocular haplopia function in six patients was reconstructed in the primary position after surgery. Horizontal rectus transposition combining recess-resect is easy to perform, and the number of recti involved in the surgery is small. This approach can effectively correct the eye position, improve eye movement, and reconstruct binocular vision in patients with MED by combining horizontal strabismus.

Palpebral fissure changes following horizontal recti muscles surgery

Background Strabismus surgery is a 1-day operation. It can result in aligned eyes or nearly so (orthophoria) or overcorrection or undercorrection that may require further treatment or another surgery. Aim To assess alterations in vertical palpebral fissure height following horizontal recti muscle surgery (recession or resection) for the treatment of horizontal strabismus (esotropia or exotropia). Patients and methods A prospective interventional case series was carried out on 68 eyes of 41 patients with horizontal strabismus (exotropia or esotropia), comitant or incomitant (paralytic), who underwent surgical correction. Patients were subdivided into three groups: group I (n=50) underwent recession only, group II (n=10) underwent resection only, and group III (n=8) underwent recession and resection. All patients were subjected to preoperative, operative, and postoperative evaluations (palpebral fissure height and width measurement). Results Distant angle of exotropia was considerably lower in group I than group III (P2&lt;0.019) but were insignificantly different between groups I and II and between groups II and III. Palpebral fissure at 6 months was considerably lower in group II than groups I and III (P=0.013 and 0.019, respectively). Conclusion Horizontal rectus muscles recession for horizontal strabismus causes vertical widening of palpebral fissure height, and also resection results in narrowing of vertical palpebral fissure height. The combination of horizontal rectus muscle recession and resection for horizontal strabismus results in vertical palpebral fissure height widening in half of eyes and vertical palpebral fissure height narrowing in a quarter of the eyes.

Strabismus Surgery in Orthophoric Patients With Symptomatic, Asymmetric Vertical or Horizontal Incomitance

To report the indications, operative strategies, and surgical outcomes of patients who undergo vertical and horizontal rectus muscle surgery for incomitant strabismus despite being orthophoric in primary gaze. Retrospective, interventional case series. The setting for this study was an academic practice at Boston Children's Hospital. The patient population comprised 8 orthophoric patients who underwent strabismus surgery to treat vertical/horizontal incomitance. Observation procedures included review of surgical strategies, strabismus measurements in diagnostic gaze positions, and development of postoperative diplopia. The main outcome measures were preserved single vision in primary gaze, comitance, reoperation rate, and patient/surgeon satisfaction. Surgical strategies included the following: (1) simultaneous recession of ipsilateral antagonist rectus muscles; (2) recession or resection of 1 rectus muscle with balancing surgery on the fellow eye; (3) restricting the range of 1 muscle (combined resection and recession or posterior fixation suture); and (4) creating an acceptable deviation in primary gaze. Mean follow-up was 5.4 months (median, 2 months; range, 2-25 months). No patient had new-onset primary gaze diplopia. The median incomitance improved by 9.5 prism diopters. No patient required additional surgery. Patient satisfaction and surgeon assessment of outcomes were high. Although the risk of operating on orthophoric patients with incomitant strabismus may discourage surgeons from offering treatment, the use of specific strategies to address incomitance can preserve alignment in primary gaze while improving patient satisfaction. These strategies may also benefit patients with incomitant strabismus that is symptomatic in primary gaze.

Surgical Treatments to Improve Visual Acuity in Infantile Nystagmus Syndrome: A Report by the American Academy of Ophthalmology

To review the literature on the efficacy of surgical procedures to improve visual acuity (VA) in patients with infantile nystagmus syndrome (INS). Literature searches were last conducted in January 2022 in the PubMed database for English-language studies with no date restrictions. The combined searches yielded 354 abstracts, of which 46 were reviewed in full text. Twenty-three of these were considered appropriate for inclusion in this assessment and were assigned a level of evidence rating by the panel methodologist. One included study was a randomized trial; the remaining 22 were case series. The 23 studies included children and adults with INS and a variable proportion with anomalous head position (AHP), strabismus, and sensory diagnoses. The surgical interventions evaluated included large recessions, tenotomy and reattachment (TAR), myectomy with or without pulley fixation, and anterior extirpation of the 4 horizontal rectus muscles, as well as various procedures to correct an AHP in which VA was reported as a secondary outcome. The data were mixed, with improvements in binocular best-corrected visual acuity (BCVA) ranging from no improvement to 0.3 logarithm of the minimum angle of resolution (logMAR), or 3 lines. (Most studies were in the range of 0.05-0.2 logMAR.) Statistically significant improvement in VA was noted in 12 of 16 studies (75%) that performed statistical analyses, with no clear advantage of any single procedure. Complications and reoperations were lowest in patients who underwent TAR and highest in those who underwent myectomy or anterior extirpation. The best available evidence suggests that eye muscle surgery in patients with INS results in a modest improvement in VA. Proprietary or commercial disclosure may be found after the references.

Retinal and choroidal microvasculature is altered after strabismus surgery.

To evaluate the retinal and choroidal microvasculature after strabismus surgery using swept-source optical coherence tomography angiography (OCTA). Thirty-three eyes of 33 patients who underwent horizontal rectus surgery for strabismus were included in this retrospective study. The unoperated fellow eyes were used as the control group. The macular microvasculature was assessed using a 3 × 3 scan pattern centred on the fovea preoperatively, and one week and one month postoperatively. The vessel density (VD) of superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC) were automatically analyzed. The foveal avascular zone (FAZ) was calculated manually using the tool of the device. The VD in SCP demonstrated a significant difference between operated and fellow eyes at one week (p = 0.017). Moreover, a significant increase was observed in the mean VD values in SCP of operated eyes after surgery (p = 0.037). The VD in DCP exhibited no significant differences between operated and fellow eyes before and after strabismus surgery. However, there was a significant difference in VD was observed between operated and fellow eyes one week after surgery (p = 0.001). The mean VD in CC was significantly increased in the operated eyes one week after surgery compared to preoperative values (p = 0.006). This study revealed that strabismus surgery may cause transient alterations both in retinal and choroidal microcirculation in the early postoperative period.

Superior rectus recession combined with lateral rectus recession and Y-split surgery for exotropia with large comitant innervational hypertropia in a case of type III Duane retraction syndrome

The aim of this study is to report a case of hypertropia with severe globe retraction and innervational upshoot present in type III Duane retraction syndrome (DRS) and its management. We report a case of a 24-year-old male with type III DRS with large hypertropia and exotropia, 90° upshoot (grade 4) on attempted adduction, globe retraction on adduction and depression and significant face turn. MRI brain and orbit revealed absence of right abducens nerve with relative low position of horizontal rectus muscles, representing the bridle effect, with normal inferior rectus and superior rectus. The case was managed by performing right eye lateral rectus recession with Y-split for the severe upshoot and superior rectus recession for the hypertropia. Recession of the superior rectus muscle along with lateral rectus recession with Y-split is a safe and effective treatment of type III DRS cases with hypertropia and exotropia.

Laser speckle contrast imaging enables perfusion monitoring of the anterior segment during strabismus surgery: a study on the horizontal rectus muscles

BackgroundA dreaded complication of strabismus surgery is anterior segment ischaemia (ASI), caused by damage to the anterior ciliary arteries. To avoid ASI, a maximum of two rectus muscles are operated...

Analysis of the Changes and Possible Reasons in Aberrations before and after Surgery in Patients with Concomitant Exotropia.

Objective The objective is to observe the changes in aberrations before and after surgery in patients with common horizontal strabismus and to analyze the possible reasons for the changes. Methods Forty eyes of 40 cases with concomitant exotropia who underwent strabismus correction at the Ophthalmology Department of Nantong University Hospital from October 2020 to July 2021 were included in this study, all of whom underwent unilateral lateral rectus recession combined with a medial rectus resection in the same eye. Aberration parameters were measured 1 day before surgery and 1 week, 1 month, 3 months, and 6 months after surgery. Differences in the indicators at each time period were compared by analysis of variance (ANOVA) of repeated measures data for a single factor, and data were analyzed using SPSS 25.0 statistical application software. Results 5 mm pupil diameter: the preoperative and postoperative RMS of total aberration showed statistically significant difference (P < 0.01). Postoperation test (Bonferroni method) and preoperative comparison at each period after surgery showed statistically significant differences between 6 months after surgery (P=0.002) and preoperative comparison. The preoperative and postoperative comparison of RMS in LOAs was statistically significant (P < 0.01); postoperative test (Bonferroni method) and preoperative comparison showed that there were statistically significant differences between 1 week (P=0.033) and 6 months (P=0.002) after operation. The difference of RMS of defocus before and after operation was statistically significant (P < 0.01); postoperation test (Bonferroni method) and preoperative comparison showed that there was statistically significant difference between 6 months after operation (P=0.007) and preoperative comparison. There was statistically significant difference in preoperative and postoperative RMS of HOAs (P=0.013). Postoperative test (Bonferroni method) and preoperative comparison showed that there was statistically significant difference 6 months after surgery (P=0.03). The RMS of secondary astigmatism showed a statistically significant difference before and after operation (P=0.001), and the postoperation test (Bonferroni method) showed a statistically significant difference 6 months after operation (P=0.002). In 5 mm pupil diameter, the preoperative and postoperative RMS of total aberration showed statistically significant difference (P < 0.01), postoperative test (Bonferroni method) was used to compare each period after surgery with that before surgery, and there were statistically significant differences between 1 week after surgery (P=0.034), 3 months after surgery (P=0.033), and 6 months after surgery (P=0.003). The preoperative and postoperative comparison of RMS in LOAs was statistically significant (P < 0.01), postoperative test (Bonferroni method) was used to compare each period after surgery with that before surgery, and there were statistically significant differences between 1 week after surgery (P=0.04), 3 months after surgery (P=0.034), and 6 months after surgery (P=0.004). The difference of RMS of defocus before and after surgery was statistically significant (P=0.002), and the comparison between postoperation test (Bonferroni method) and preoperation showed that the difference was statistically significant 6 months after surgery (P=0.027). The RMS of astigmatism showed statistically significant difference before and after operation (P=0.002), and the postoperation test (Bonferroni method) showed statistically significant difference between 6 months after operation (P=0.009) and before operation. Conclusion We found that horizontal rectus surgery had a transient effect on LOAs and almost no effect on HOAs. Long-term follow-up is recommended after strabismus surgery to observe eye position and binocular visual function. Because of the high prevalence of strabismus in adolescents, long-term observation of the eye axis and aberration is recommended.

Reduced activity of vertically acting motoneurons during convergence.

Previous studies have revealed unexpected relationships between the firing rates of horizontally acting motoneurons and vergence. During a vergence task, for example, antidromically identified abducens internuclear neurons show a negative correlation between vergence angle and firing rate, which is the opposite of the modulation displayed by the medial rectus motoneurons to which they project. For a given horizontal eye position, medial rectus motoneurons discharge at a higher rate if the eyes are converged than if the same eye position is reached during a task that requires version; paradoxically, however, the horizontal rectus eye muscles show corelaxation during vergence. These complex and unexpected relationships inspired the present author to investigate whether the tonic firing rates of vertically acting motoneurons in oculomotor nucleus are correlated with vergence angle. Monkeys were trained to fixate a single, randomly selected, visual target among an array of 60 red plus-shaped LEDs, arranged at 12 different distances in three-dimensional space. The targets were arranged to permit dissociation of vertical eye position and vergence angle. Here I report, for the first time, that most vertically acting motoneurons in oculomotor nucleus show a significant negative correlation between tonic firing rate and vergence angle. This suggests the possibility that there may be a general corelaxation of extraocular muscles during vergence.NEW & NOTEWORTHY An array of 60 plus-shaped LEDs, positioned at various locations in three-dimensional space, was used to elicit conjugate and disjunctive saccades while single neurons in oculomotor nucleus were recorded from rhesus monkeys. This study demonstrates that most vertically acting motoneurons in oculomotor nucleus discharge at a lower rate when the eyes are converged.