PurposeTo study the surgical outcomes of inferior oblique (IO) myectomy in patients with unilateral superior oblique (SO) palsy and mild to moderate hypertropia (≤15 PD) in the primary position.MethodsThis retrospective study included 36 eyes of 36 patients who underwent IO myectomy for unilateral SO palsy between 2017 and 2023. Patients with bilateral SO palsy, primary position hypertropia >15 PD, prior strabismus surgery, or SO tendon laxity on Guyton's exaggerated traction test were excluded. Hypertropia in different gaze positions, oblique muscle action, and other parameters were evaluated preoperatively and at the final follow-up.ResultsThe mean age was 25.1 ± 13.1 years (range: 8-58), and 58% were male. Mean follow-up was 18.1 ± 9.8 months (range: 6-42). Hypertropia decreased significantly in primary and reading positions, from 10.2 ± 3.7 PD (range: 4-15) and 11.0 ± 3.8 PD (range: 5-15) preoperatively to 1.9 ± 2.3 PD (range: 0-8) and 2.2 ± 2.7 PD (range: 0-8) postoperatively (p < 0.001). IO overaction decreased from 2.4 ± 0.9 (range: 1-4) to 0.4 ± 0.6 (range: 0-2), and SO underaction improved from -2.1 ± 0.7 (range: -3 to -1) to -0.3 ± 0.4 (range: -1 to 0) (both p < 0.001). Excyclotorsion was present in 72% preoperatively and decreased from 4.0° ± 2.8° (range: 0-8) to 1.7° ± 1.6° (range: 0-4) (p < 0.001). Abnormal head position (AHP) was present in 26/36 patients (72%) and resolved in 81%, while diplopia was reported in 22/36 patients (61%) and resolved in 77%.ConclusionIO myectomy is a simple, effective, and safe procedure for mild to moderate hyperdeviation secondary to unilateral SO palsy; however, these findings should be interpreted in light of the study's retrospective design and modest sample size.

To evaluate the characteristics and treatment outcomes for presumed unilateral congenital superior oblique palsy (SOP) in adults. Retrospective medical records of adult patients diagnosed with presumed unilateral congenital SOP were included. Presumed unilateral congenital SOP was defined as manifesting vertical diplopia and/or head tilt with an insidious or subacute onset or duration of over one year, vertical misalignment greater than 10 prism diopters (PD) and a positive Bielschowsky head tilt test, and/or underaction of the superior oblique (SO) muscle or overaction of its antagonistic inferior oblique muscle on the affected side. The clinical manifestations and surgical treatment outcomes of presumed congenital SOP in adults were evaluated. Among adult patients initially diagnosed with unilateral SOP, 41% were classified as presumed congenital SOP. Patients exhibited various clinical manifestations beyond the typical over-elevation or under-depression during adduction, with the greatest deviation in the field of action of the SO muscle observed in only 6.9% of cases. Orbital imaging revealed SO asymmetry due to the SO hypoplasia in 58.5% of patients. Among various factors, combined horizontal strabismus was more common in those with symmetric SO, with no significant differences in clinical presentation or surgical outcomes based on SO volume. The overall surgical outcome for presumed congenital SOP was generally favorable, with an 85% success rate. No factors including the presence of SO hypoplasia influenced the surgical result. In adults with presumed congenital SOP, diverse clinical manifestations were observed. The angle of deviation, duction and version patterns, and treatment outcomes were not associated with the presence of SO hypoplasia on MRI. Despite the diversity in clinical features, treatment outcomes remained favorable. Retrospectively registered.

The diagnosis of unilateral congenital superior oblique muscle (SOM) palsy relies on a cluster of clinical findings due to the absence of a definitive confirmation test. This study aimed to compare qualitative and quantitative magnetic resonance imaging (MRI)-based assessments and to define a standardized quantitative threshold for diagnosing SOM atrophy. Patients with unilateral congenital SOM palsy who underwent orbital MRI, matched with age- and sex-paired controls were included. MRI images were assessed qualitatively (SOM atrophy) and quantitatively (surface and area measurements along the muscle axis) using multiplanar reconstructions. Ratios between the paralytic and non-paralytic SOM, as well as the inferior rectus muscle as a control, were analyzed. Inter-rater reliability, diagnostic thresholds, and diagnostic performance of quantitative measurements were evaluated. A total of 120 subjects (60 patients and 60 controls) were included. The inter-rater agreement for SOM atrophy detection was good to excellent for both qualitative and quantitative methods. Qualitative assessment identified SOM atrophy in 46.7–48.3% of cases, while quantitative analysis showed significantly smaller SOM surface and area on the affected side (p < 0.001). The optimum diagnostic thresholds for SOM palsy were a surface ratio < 0.9 or an area ratio < 0.8 between the paralytic and non-paralytic SOM, correctly diagnosing 78.3% of cases while yielding a 10% false-positive rate. As a complement strategy to trochlear nerve visualization, a stepwise approach combining qualitative and quantitative assessments enhances the evaluation of SOM atrophy. The Eye-Surface-Area (ESA) method including three steps (1) Qualitative assessment (2) Surface measurement and (3) Area measurement provides a reliable method for identifying SOM atrophy.

Simulations suggest that displacement of rectus extraocular muscle pulleys in superior oblique (SO) palsy accounts for incomitant strabismus patterns even without postulating SO contractile weakness. We asked how rectus extraocular muscle pulleys reorient during head tilt in SO palsy. In 13 subjects with unilateral SO palsy, supine magnetic resonance imaging (MRI) in 2-mm-thick quasi-coronal planes in target-controlled central gaze was repeated in both lateral decubitus positions equivalent to 90° head tilts. From extraocular muscle centroids, we computed oculocentric pulley coordinates and compartmental posterior partial volumes (PPVs) of the rectus and SO muscles. Validating atrophy, PPV of the palsied SO was smaller than its fellow (P < 10-4). In fellow orbits, the array of all four rectus pulleys exhibited counter-rotation during head tilt (P < 0.03), averaging 5.9°. The palsied pulley array was in both tilts excyclorotated relative to the fellow orbit, particularly by 4° to 5° for horizontal rectus pulleys (P < 0.03), and also counter-rotated with head tilt similarly to the fellow orbit. Differential compartmental changes in PPV were significant in the lateral and superior rectus and SO muscles of the fellow orbit that were consistent with observed torsion, but were absent in the palsied orbit. Similar counter-rotation of the rectus pulley array during head tilt occurs in both eyes in unilateral SO palsy, but superimposed on excyclorotation of the array in the palsied orbit. Differential compartmental change in PPV occurs during head tilt in the lateral and superior rectus muscles of the fellow but not palsied orbit and could augment ocular counter-rolling.

PurposeTo compare spectral domain optical coherence tomography (OCT) and color fundus photography (CFP) for assessing ocular cyclotorsion in unilateral congenital superior oblique palsy (SOP) before and after inferior oblique disinsertion.MethodsThis prospective pilot study evaluated 18 patients (36 eyes) with unilateral congenital SOP. Disc-foveal angle (DFA) was measured preoperatively and 3 months postoperatively using CFP (analyzed with ImageJ) and Spectralis OCT (with FoDi software). Contralateral nonparetic eyes served as controls.ResultsPreoperative hypertropia (14.31 ± 4.15 prism diopter, PD) significantly improved postoperatively (1.46 ± 1.98 PD, P < 0.001). CFP measurements showed significantly greater cyclotorsion in paretic versus nonparetic eyes preoperatively (P = 0.001), while OCT revealed no inter-eye difference (P = 0.295). In paretic eyes, CFP-derived DFAs were significantly higher than OCT values both preoperatively (12.26 ± 4.72° vs. 8.87 ± 4.56°, P = 0.002) and postoperatively (7.25 ± 5.18° vs. 4.33 ± 3.98°, P = 0.005). Nonparetic eyes showed no significant inter-method differences at either timepoint (all P > 0.05). Inter-method reliability was moderate preoperatively (ICC = 0.693 paretic, 0.657 nonparetic) and improved postoperatively (ICC = 0.718 and 0.921, respectively). Bland-Altman analysis demonstrated narrowing limits of agreement postoperatively (nonparetic: 8.48° to 4.40°; paretic: 7.97° to 7.50°), with no systematic bias.ConclusionSpectralis OCT with FoDi software provides a clinically useful alternative to CFP for cyclotorsion assessment in congenital SOP, though it may systematically underestimate DFA values in paretic eyes.

ABSTRACT Purpose: To compare the differentiating clinical features of subjective cyclovertical deviation and objective ocular torsion in elderly patients with cyclovertical sagging eye syndrome (CSES) versus superior oblique palsy (SOP). Study design: Prospectivestudy. Methods: Patients with CSES (n = 22) and unilateral SOP (n = 20) aged ≥50 years were included. Subjective cyclovertical deviation was measured in the primary, secondary, and third-gaze positions using a synoptophore. The disc-fovea angle (DFA), which evaluates objective ocular torsion, was measured using fundus photographs. Results: The subjective vertical deviation of the primary position was 1.3° (median) in the CSES group and 4.3° in the SOP group (p < .001). Vertical deviation was larger in the SOP than CSES group in all gaze positions (p < .05). The subjective cyclodeviation of the primary gaze was −6.0° (-: excyclo) in the CSES and SOP groups(p = .48). Cyclodeviation was larger in the SOP group in downgaze positions (p < .05). The mean DFAs were −11.5° in CSES group and −11.8° in SOP group for the hypertrophic eye (p = .85), and −12.2° in CSES group and −16.3° in SOP group for the hypotropic eye (p < .01). The ratio of patients with a larger DFA in the hypertropic than hypotropic eye was 9/22 (41.0%) in the CSES group and 4/20 (20%) in the SOP group. Conclusions: SOP has a larger hypertropia than SES. Excyclotorsion does not help distinguish in primary position but if it is somewhat larger in downgaze more likely SOP. DFA showed no obvious clinical differences; it is difficult to distinguish the two diseases from DFA.

Comparative analysis of clinical features following inferior oblique recession surgery for unilateral congenital superior oblique palsy.

ABSTRACT Purpose: To evaluate the surgical outcomes of two inferior oblique muscle weakening procedures in the management of unilateral superior oblique muscle palsy (SOP). Methods: Files of all SO palsy patients with 11-20 PD hypertropia (HT) who were treated either by inferior oblique myectomy (IOM) or inferior oblique anterior transposition (IOAT) were retrospectively reviewed. Demographic characteristics such as sex, age, etiology, simultaneous horizontal deviation, and diplopia were noted. The two techniques were compared through HT correction (in the primary position, contralateral gaze, and ipsilateral tilt) and head tilt correction. Subgroup analysis was performed in the moderate group (11-15 PD HT) and large group (16-20 PD HT). Results: This study included 69 patients in the IOM group and 55 patients in the IOAT group. The demographic characteristics of both groups were similar. Although both procedures successfully corrected the abnormal head tilt, IOAT achieved significantly more HT correction compared to IOM (p-value: 0.003). While both techniques were equally effective in the moderate group, IOAT resulted in more primary position HT correction (16.4 vs. 12.9 PD) in the large group. However, anti-elevation syndrome occurred in 5.4% of patients treated by IOAT. Conclusions: IOAT achieved more HT correction compared to IOM, particularly in patients with large preoperative HT. The lower risk of under-correction following IOAT must be weighed against its potential risk of anti-elevation syndrome

PurposeTo investigate the surgical outcomes of three different types of inferior oblique muscle weakening procedures in patients with mild hypertropia due to unilateral superior oblique muscle palsy.MethodsWe reviewed surgical data of patients aged 30 years with unilateral superior oblique palsy. The patients were categorized into three groups in terms of the surgical procedure: inferior oblique myectomy (IOM), inferior oblique recession (IOR), and inferior oblique disinsertion (IOD). Patients with preoperative hypertropia of 6 to 10 prism diopters (PD) were selected as mild cases for further comparison. Demographic data, preoperative and postoperative deviations in the primary position, contralateral gaze, contralateral elevation gaze, and ipsilateral tilt were considered for analysis. Complete success was defined as achieving postoperative orthotropia in addition to the resolution of diplopia and head tilt.ResultsA total of 82 patients with an average age of 11.8 years were included in this study. The male-to-female ratio was 1.27, and the most common cause of palsy was congenital (89%). Fifty-six patients were treated with IOM, thirteen with IOR, and thirteen with IOD. The mean hypertropia correction was significantly better in the IOM group (9.1 PD) than in the IOR (7.1 PD) and IOD (7.5 PD) groups. Complete success was achieved in 80.3% of the IOM group, 69.2% of the IOR group, and 84.6% of the IOD group. The reoperation rate was 1.7% in the IOM group and 7.6% in the IOR group.ConclusionCompared to IOR and IOD procedures, IOM was more effective in correcting hypertropia in patients with inferior oblique muscle overaction and mild hypertropia secondary to unilateral superior oblique palsy.

ABSTRACT Purpose: To compare the surgical outcomes of One- versus Two-vertical muscle surgery in patients with unilateral superior oblique muscle palsy (SOP) with primary position hypertropia (HT) over 20 PD. Patients in Group 1 underwent inferior oblique anterior transposition plus resection (IOATR), while patients in Group 2 underwent inferior oblique anterior transposition (IOAT) along with contralateral inferior rectus (IR) recession. Methods: Medical data of all SOP patients treated by either procedure from 2000 to 2023 in our strabismus center were recruited. We compared surgical outcomes between Group 1 and Group 2 by analyzing HT correction, rate of under-correction, and over-correction. Results: The study included 33 patients in Group 1 and 23 in Group 2. Both groups were similar in age, sex, etiology, affected side, diplopia, and head tilt. Group 2 achieved higher HT correction in all measured gazes. Group 1 had a higher risk of under-correction (18.18% in Group 1 vs 8.69% in Group 2) while Group 2 had a higher rate of over-correction (21.73% vs 0% in Group 1). Conclusion: In patients with severe unilateral SOP, Two-vertical muscle surgery achieved higher amounts of HT correction in all gazes despite a significantly higher risk of over-correction.

Clinical outcomes of inferior oblique myectomy in age categorized patients with unilateral superior oblique palsy

Surgical outcomes in patients with congenital superior oblique palsy: A comparison between clinical and radiological diagnosis

The purpose is to report the results of the Boergen modification of the Harada-Ito procedure with and without simultaneous vertical muscle surgery in patients with acquired unilateral superior oblique muscle palsy. Files of patients with acquired unilateral superior oblique muscle palsy who were treated with Boergen modification of the Harada-Ito procedure were studied retrospectively. For each patient, age at the time of surgery, the presence of diplopia, compensatory head posture, and ocular deviation before and after surgery were retrieved. Results were evaluated 6 months after surgery. A total of 12 patients with a mean age of 32 years at the time of surgery (range 15-45 years) were included. The underlying etiology was head trauma in eleven patients. The modified Harada-Ito procedure alone was done for three cases (Group 1), and a simultaneous combination of this procedure and vertical muscle surgery was performed in nine patients (Group 2). The average intorsional effect in the primary position was 9.2° (8° in Group 1 and 9.6° in Group 2). The average correction of hypertropia in the primary position was 8.2 prism diopters (PD) (1 PD in Group 1 and 10.6 PD in Group 2). Diplopia in the primary position and downgaze were resolved in eleven patients and ten patients, respectively. Four patients had a compensatory head tilt at their last follow-up. Boergen modification of the Harada-Ito procedure, alone and combined with vertical muscle surgery, successfully corrected primary position diplopia in the majority of the patients.

Purpose The aim of this study was to assess the effect of unilateral inferior oblique (IO) anteriorization as a single muscle surgery for treatment of unilateral superior oblique palsy (SOP) with large angle hypertropia. Patients and methods This is a retrospective study that included 28 patients, for whom IO anteriorization was performed for treatment of ipsilateral SOP with large angle hypertropia more than or equal to 20 prism diopters (PD). The patients were evaluated preoperatively and 3 months postoperatively for the vertical deviation (VD) in primary position and in adduction. Residual hypertropia less than or equal to 6 PD in primary position postoperatively was considered a successful outcome, together with improvement of the abnormal head tilt. Results The mean age of the patients was 30.75±17.05 years. The mean preoperative VD in the primary position was 25.29±4.50 PD. It significantly decreased postoperatively to 5.54±5.25 PD (P&lt;0.001). The mean preoperative VD in adduction was 30.57±7.89 PD and decreased postoperatively to 8.50±5.27 PD (P&lt;0.001). The preoperative IO overaction grade was 2.61±0.99 and decreased postoperatively to 0.39±0.50 (P&lt;0.001). Successful outcome was reported in 75% of the cases and improvement of head tilt occurred in 78% of the patients. Conclusion IO anteriorization could be a simple one muscle surgery to correct large angle VD associated with unilateral SOP with a favorable outcome.

Postoperative outcomes for unilateral congenital trochlear nerve palsy: A retrospective cohort study

ObjectivesTo evaluate the effect of inferior oblique (IO) myectomy on ocular torsion according to the absence of the trochlear nerve in unilateral congenital superior oblique palsy (UCSOP).MethodsWe retrospectively reviewed the clinical data of patients who had been diagnosed with UCSOP and underwent ipsilateral IO myectomy (n = 43). Patients were classified into the present and absent groups according to the absence of the trochlear nerve and superior oblique hypoplasia on magnetic resonance imaging (MRI). For quantitative analysis of ocular torsion, disc-fovea angles (DFA) were collected in both eyes using fundus photographs taken within three months before surgery and one month after surgery.ResultsDFA of the paretic eye did not differ according to the absence of the trochlear nerve (9.4±5.6° in the present group vs. 11.0±5.4° in the absent group, p = 0.508). However, the present group had a larger DFA in the non-paretic eye than the absent group (14.1±6.7° in the present group vs. 8.0±5.0° in the absent group, p = 0.003). The change of ocular torsion after IO myectomy in the paretic eye was -5.3±3.7° in the present group and -4.8±3.5° in the absent group, respectively (p = 0.801). In the non-paretic eye, the change in DFA was -1.5±3.0° in the present group, which was larger than that in the absent group (0.7±2.6°, p = 0.047). In the multivariate analysis, the change in DFA was correlated with only the preoperative DFA (standardized β = -0.617, p<0.001 in the paretic eye, and standardized β = -0.517, p<0.001 in the non-paretic eye).ConclusionsIn the paretic eye, there was no significant difference in the change of ocular torsion between both groups, whereas in the non-paretic eye, the present group had a larger change in DFA after IO myectomy than the absent group. However, in the multivariable analysis, the change in ocular torsion was significantly correlated with preoperative excyclotorsion but not with the presence of the trochlear nerve itself.

PurposeAlthough the three-step test (3ST) is typically used to diagnose superior oblique palsy (SOP), sagging eye syndrome (SES) has clinical similarities. We sought to determine if alignment measurements can distinguish unilateral SOP from hypertropia in SES.MethodsWe studied hypertropic subjects who underwent surface-coil magnetic resonance imaging (MRI) demonstrating either SO cross-section reduction indicative of congenital or acquired palsy (SOP group) or lateral rectus muscle sag (SES group). Alignment was measured by Hess screen and prism-cover testing. Multiple supervised machine learning methods were employed to evaluate diagnostic accuracy. Rectus pulley coordinates were determined in SES cases fulfilling the 3ST.ResultsTwenty-three subjects had unilateral SOP manifested by SO atrophy. Eighteen others had normal SO size but MRI findings of SES. Maximum cross-section of the palsied SO was much smaller than contralaterally and in SES (P < 2 × 10−5). Inferior oblique cross-sections were similar in SOP and SES. In both SOP and SES, hypertropia increased in contralateral and decreased in ipsilateral gaze and was greater in ipsilateral than contralateral head tilt. In SES, nine subjects (50%) fulfilled the 3ST and had greater infraplacement of the lateral than medial rectus pulleys in the hypotropic orbit. Supervised machine learning of alignment data distinguished the diagnoses with areas under the receiver operating curves up to 0.93, representing excellent yet imperfect differential diagnosis.ConclusionsBecause the 3ST is often positive in SES, clinical alignment patterns may confound SES with unilateral SOP, particularly acquired SOP. Machine learning substantially but imperfectly improves classification accuracy.

To evaluate the therapeutic effect of temporal slant recession of the inferior rectus muscle (TSRIRM) for the treatment of small vertical deviations in patients with vertical diplopia, with consideration of the theoretical additive effects of this procedure on ocular torsion and horizontal incomitance. Retrospective review of 11 patients who were treated with TSRIRM. Eight patients with vertical diplopia and small hyperdeviations (up to 6 prism diopters (PDs)) were treated with isolated TSRIRMs. Three patients with vertical diplopia from unilateral superior oblique palsies with large hyperdeviations (>15 PDs) were treated with TSRIRMs in conjunction with contralateral inferior oblique recessions. Six of the 8 patients with small vertical deviations had successful vertical realignment with elimination of symptomatic diplopia after an isolated TSRIRM. Two of the eight patients had residual hypertropia with symptomatic diplopia. Three additional patients with unilateral superior oblique palsy had successful vertical realignment with elimination of symptomatic diplopia after ipsilateral inferior oblique recession and contralateral TSRIRM. In total, 9 of 11 patients had successful surgical results after TSRIRM. TSRIRM provides an effective and reliable treatment for small angle vertical strabismus. Its ease of surgical access renders it useful for implementation in an outpatient neuro-ophthalmology setting.

Masquerading Superior Oblique Palsy

BackgroundTo investigate preoperative clinical features and postoperative results according to the correspondence between excyclotorsion and the paretic eye in patients with congenital unilateral superior oblique palsy (USOP).MethodsA retrospective review of medical charts was performed. The patients were divided into the accordance (ocular excyclotorsion in the paretic eye) and disaccordance (ocular excyclotorsion in the non-paretic eye) groups. The degree of excyclotorsion (scale, 0–4) was measured. Age, sex, hypertropia at the primary position, fixation preference, inferior oblique overaction, and degree of excyclotorsion were measured.ResultsNinety-eight patients were included in this study. There were 70 (71.4%) and 28 patients (28.6%) in the accordance and disaccordance groups. Sixteen patients (22.9%) in the accordance group and 12 patients (42.9%) in the disaccordance group were aged under 2 years (p = 0.04). A fixation preference of the paretic eye was observed in 2 (2.9%) and 8 (28.6%) patients in the accordance and disaccordance groups (p < 0.01). The postoperative degree of excyclotorsion in the accordance group (0.14 ± 0.39) was lower than that in the disaccordance group (0.28 ± 0.71) (p = 0.01). The residual postoperative excyclotorsion (> 1) were observed in the disaccordance group (14 patients, 50%) and accordance group (16 patients, 22.9%) (p = 0.01).ConclusionPreoperative disaccordance between excyclotorsion and the paretic eye was observed in patients who were under 2 years of age and preferred fixation of the paretic eye. The postoperative degree of excyclotorsion was lower in the accordance group.