Clinical factors underlying a single surgery or repetitive surgeries to treat superior oblique muscle palsy

Clinical characteristics and surgical outcomes in patients with superior oblique muscle palsy: a retrospective study on 1057 patients

BACKGROUND

To evaluate the clinical findings of patients with SOP who underwent surgery.

METHODS

This historical cohort study was performed on 1057 SOP patients managed with surgery in Farabi Hospital, Iran, from 2011 to 2022.

RESULTS

There were 990 (93.7%) patients with unilateral SOP with the mean age of 21.8 ± 14.8 years. Of these, 715 patients (72.2%) were diagnosed with congenital SOP, and 275 patients (27.8%) had acquired SOP (P < 0.001). In contrast, 67 (6.3%) patients were diagnosed with bilateral SOP, with the mean age of 19.4 ± 15.6 years. Among these, 18 cases exhibited the masked type. The mean angle of vertical deviation in primary position at far in unilateral and bilateral cases was 15.6 ± 8.3 and 13.3 ± 9.1 △, respectively (P < 0.001). In unilateral cases, abnormal head posture (AHP) was detected in 847 (85.5%) patients and 12 (1.2%) had paradoxical AHP. Amblyopia was found in 89 (9.9%) unilateral and 7 (10.3%) bilateral cases. Solitary inferior oblique myectomy, was the most common surgery in both unilateral (n = 756, 77.1%) and bilateral (n = 35, 52.2%) patients. The second surgery was performed for 84 (8.6%) unilateral and 33 (49.3%) bilateral cases (P < 0.001). The prevalence of amblyopia and the mean angle of horizontal deviation were significantly higher in patients who needed more than one surgery (all P < 0.05).

CONCLUSION

Congenital SOP was more than twice as frequent as acquired SOP and about 90% of unilateral and 50% of bilateral cases were managed with one surgery. Amblyopia and significant horizontal deviation were the most important factors for reoperation.

TRIAL REGISTRATION

The Institutional Review Board approval was obtained from the Tehran University of Medical Sciences (IR.TUMS.FNM.REC.1400.012) and this study adhered to the tenets of the Declaration of Helsinki and HIPAA.

Pre- and postsurgical measurements in patients with strabismus sursoadductorius a retrospective study

PURPOSE

Strabismus sursoadductorius is the most common strabismus of the oblique eye muscles. The changes in squint angle, elevation in adduction, abnormal head posture and binocular vision were collected to get an overview of the results at the largest clinic in Austria.

METHODS

This study is a retrospective study. The orthoptic and ophthalmologic parameters of 102 patients who were treated in the Department of Ophthalmology and Optometry between January 2017 und September 2020 were collected and statistically analysed.

RESULTS

The mean age was 12.2 ± 14.8 years. The squint angle changed from 18.3 ± 6.3 presurgical to 13.4 ± 9.7 (p = 0.09) with Hirschberg measurement. The squint angle changed from 12.5 ± 7.7 to 6.7 ± 4.9 (p < 0.01) at distance and from 12.5 ± 7.6 to 6.1 ± 4.5 (p < 0.01) at near with the prism covertest. Elevation in adduction showed a highly significant change (p < 0.01) from 15 ± 5.6 to 1.4 ± 2.8 degrees on average postsurgical. In binocular vision at distance there was also a highly significant (p < 0.01) change with 21.6% to postsurgical 37.3% positive tests. At near, the positives also increased significantly (p = 0.01) from 32.4% to 39.2%. There was no significant change in stereo vision (p = 1.0). Presurgical 52.9% of the sample had an abnormal head posture, postsurgical it was 38.2%, this change is also highly significant (p < 0.01).

CONCLUSION

The change was significant to highly significant for most parameters (i.e., squint angle, elevation in adduction, and abnormal head posture).

Types of Surgery Performed and Reoperation Rate for Congenital Superior Oblique Palsy: a Claims Database Study

PURPOSE

To investigate types of surgeries performed to treat a presumed congenital superior oblique palsy (SOP) and the reoperation rate.

METHODS

This was a population-based retrospective cohort study using claims data from the United States. Patients who underwent strabismus surgery for a presumed congenital SOP with ≥ 3 months of continuous enrolment after the initial surgery were included. We investigated age, surgical methods and the time interval between the initial surgery and reoperation. The hazard ratios for reoperation were estimated according to the surgical methods using Cox regression analysis.

RESULTS

A total of 3,998 patients underwent surgery for presumed congenital SOP; 2,981 (74.6%) on only one vertical muscle (excluding superior oblique). Reoperation was performed on 427 patients (10.7%). Compared to patients who underwent unilateral surgery on one vertical muscle (excluding superior oblique muscle), patients who underwent surgery that included the superior oblique muscle (unilateral 2.08; 95% CI, 1.61-2.67, p < 0.001; bilateral 2.44; 95% CI, 1.40-4.28, p = 0.002) and two or more vertical muscles (excluding the superior oblique muscle) (unilateral 2.99; 95% CI, 2.00-4.49, p < 0.001; bilateral 1.68; 95% CI, 1.23-2.28, p = 0.001) had increased hazard ratios for reoperation. The median period between the initial surgery and reoperation was 168.0 [Q1-Q3 84.0-407.8] days and negatively correlated with patient age at initial surgery (r = -0.199, p < 0.001).

CONCLUSION

The reoperation rate for presumed congenital SOP was 10.7%. Patients who underwent surgery on two or more vertical muscles or the superior oblique muscle had an increased risk of reoperation.

Candidate Genes in Testing Strategies for Linkage Analysis and Bioinformatic Sorting of Whole Genome Sequencing Data in Three Small Japanese Families with Idiopathic Superior Oblique Muscle Palsy

Idiopathic superior oblique muscle palsy is a major type of paralytic, non-comitant strabismus and presents vertical and cyclo-torsional deviation of one eye against the other eye, with a large vertical fusion range and abnormal head posture such as head tilt. Genetic background is considered to play a role in its development, as patients with idiopathic superior oblique muscle palsy have varying degrees of muscle hypoplasia and, rarely, the complete absence of the muscle, that is, aplasia. In this study, whole genome sequencing was performed, and single nucleotide variations and short insertions/deletions (SNVs/InDels) were annotated in two patients each in three small families (six patients in total) with idiopathic superior oblique muscle palsy, in addition to three normal individuals in one family. At first, linkage analysis was carried out in the three families and SNVs/InDels in chromosomal loci with negative LOD scores were excluded. Next, SNVs/InDels shared by the six patients, but not by the three normal individuals, were chosen. SNVs/InDels were further narrowed down by choosing low-frequency (<1%) or non-registered SNVs/InDels in four databases for the Japanese population, and then by choosing SNVs/InDels with functional influence, leading to one candidate gene, SSTR5-AS1 in chromosome 16. The six patients were heterozygous for 13-nucleotide deletion in SSTR5-AS1, except for one homozygous patient, while the three normal individuals were wild type. Targeted polymerase chain reaction (PCR) and direct sequencing of PCR products confirmed the 13-nucleotide deletion in SSTR5-AS1. In the face of newly-registered SSTR5-AS1 13-nucleotide deletion at a higher frequency in a latest released database for the Japanese population, the skipping of low-frequency and non-registration sorting still resulted in only 13 candidate genes including SSTR5-AS1 as common variants. The skipping of linkage analysis also led to the same set of 13 candidate genes. Different testing strategies that consisted of linkage analysis and simple unintentional bioinformatics could reach candidate genes in three small families with idiopathic superior oblique muscle palsy.

Photorefraction with Spot Vision Screener versus Visual Acuity Testing as Community-Based Preschool Vision Screening at the Age of 3.5 Years in Japan

Nationwide in Japan, a community-based vision-screening program in 3.5-year-old children is conducted in three steps: questionnaires and home visual acuity testing as the primary screening; visual acuity testing by nurses and pediatricians’ inspection in community health centers as the secondary screening; and examinations by ophthalmologists as the tertiary screening. In this study, we introduced photorefraction with a Spot vision screener in addition to visual acuity testing to answer the clinical question of whether photorefraction could better detect eye diseases and potentially replace visual acuity testing. Photorefraction was performed on 813 consecutive 3.5-year-old children in a center. The children were sent to tertiary examinations, which were based on the Spot vision screener standard, in addition to the visual acuity testing standard: failure in either eye to pass 0.5 visual acuity in a center. A notice to visit ophthalmologists was issued for 95 children (11%), and documents with the diagnosis were sent back to the Heath Office for 76 children (80%). The rate of children with anisometropic or ametropic amblyopia or accommodative esotropia as treatment-requiring diseases was highest in cases of no pass at both standards (10/15 = 66%), and higher in cases of no pass only at the Spot vision screener standard (13/45 = 28%), compared with cases of no pass only at the visual acuity testing standard (6/33 = 18%, p = 0.0031). Photorefraction, in addition to visual acuity testing and inspection led to additional eye diseases detection at 3.5 years. Visual acuity testing at home would not be omitted in the introduction of photorefraction.

Vertical Comitance of Hypertropia in Congenital and Acquired Superior Oblique Palsy

BACKGROUND

Ivanir and Trobe have claimed that hypertropia (HT) that is greater in upgaze than downgaze, or equal to it, is characteristic of decompensated congenital superior oblique (SO) palsy and never present in ischemic, traumatic, or tumorous SO palsy. The reliability of this claim was tested in patients with SO palsy confirmed by MRI demonstration of subnormal ipsilesional SO size.

METHODS

Quasi-coronal, surface coil MRI was performed in target-controlled central gaze to identify patients with a unilateral reduction in SO cross section indicative of palsy. Nine patients gave an unequivocal history or had markedly increased vertical fusional amplitudes indicative of congenital onset (mean age 38 ± 16 years, SD). Seven patients had unequivocal acquired onset (age 47 ± 14 years and symptom duration 5.4 ± 4.8 years), including 2 with demonstrated trochlear Schwannoma and 5 with onset after severe head trauma. Fifteen patients had gradually progressive onset unequivocally not congenital yet not associated with any identifiable precipitating event (age 52 ± 20 years and symptom duration 13 ± 14 years).

RESULTS

Maximum SO cross section averaged 8.6 ± 3.9 mm2 in congenital palsy, not significantly different from 11.3 ± 3.5 mm2 in acquired palsy (P = 0.08) either unequivocally or progressively acquired, but significantly less than about 19 mm2 contralesionally in SO palsy (P < 10-4). Although mean central gaze HT was greater at 20.6 ± 8.0Δ in 9 cases of congenital than that in 22 acquired cases at 11.4 ± 6.8Δ (P = 0.002), HT was 8.4 ± 16.3Δ less in upgaze than downgaze in congenital SO palsy and 3.7 ± 11.2Δ less in acquired SO palsy. In congenital palsy, 33% of patients had HT greater in upgaze than downgaze while in 67% HT was greater in downgaze (by up to 42Δ). In acquired SO palsy, HT was greater in upgaze than downgaze or equal to it in 8 cases (36%, P = 0.87, X2). In acquired SO palsy, HT was greater in upgaze than downgaze in 37% and greater in downgaze than upgaze in 59% of cases. The HT was equal in upgaze and centralgaze in no congenital and 3 acquired cases of SO palsy. Trends were similar in unequivocal acquired and progressive acquired (noncongenital) SO palsy (P > 0.4).

CONCLUSIONS

Hypertropia is not characteristically greater in upgaze than downgaze in congenital SO palsy proven by SO atrophy on MRI. In fact, average HT is greater in downgaze than upgaze in both acquired and congenital palsy, sometimes strikingly so in the latter. The finding of HT greater in upgaze than downgaze, or equal to it, does not reliably indicate that SO palsy is congenital, nor does maximum SO cross section.

Surgical treatment of superior oblique palsy: Predictors of outcome

PURPOSE

The purpose of this study was to evaluate the incidence and outcome of surgically treated superior oblique palsy (SOP) and the factors involved in its resolution.

METHODS

We performed a retrospective study of 76 patients who underwent surgery for SOP. We recorded data from the physical examination and the number and type of procedures performed. Favorable outcome was defined as resolution of or improvement in torticollis (≤5°) and diplopia in primary position (PP) and downgaze or as vertical deviation (VD) <5 prism diopters (pd) in PP and 10 pd in the oblique diagnostic position.

RESULTS

Mean age was 33.12 years. Congenital SOP was the most frequent type (65.8%). Mean preoperative VD was 15.89 ± 9.94 pd, decreasing to 3.07 ± 4.36 pd after surgery. Associated horizontal deviation was recorded in 51.32% of cases. The mean number of procedures was 1.37 ± 0.62 (range 1-4), with 69.7% of patients requiring only one procedure. The mean number of muscles operated on was 1.96 ± 1.01 (inferior oblique being the most frequent). A greater reduction in VD after surgery was observed in patients with congenital SOP (P = 0.04). Although none of the factors evaluated influenced surgical outcome, amblyopic patients had a greater risk of reoperation (P = 0.04). A favorable outcome was achieved in 75% of cases. Mean follow-up was 37.08 months.

CONCLUSION

Congenital SOP was twice as frequent as acquired SOP and although surgery was successful in most cases, a greater reduction in VD was obtained in congenital cases. Amblyopia was identified as a risk factor for reoperation.

Pseudoamblyopia in Congenital Cyclotropia

Purpose

To study the effect of surgery on amblyopia and suppression associated with congenital cyclovertical strabismus.

Methods

The fixation pattern was investigated with microperimetry before and soon after surgery in ten consecutive children operated for congenital superior oblique palsy at the S. Martino Hospital, Belluno, Italy, between September 2014 and December 2015. Changes in visual performance in terms of best-corrected visual acuity (BCVA) and stereopsis between the day before and one week after surgery were also evaluated. No other amblyopia treatment has been administered during the time study.

Results

Surgical correction of the excyclodeviation in congenital SO palsy determined monocular and binocular sensory consequences: monocularly, in the cyclodeviated amblyopic eye, BCVA (0.46–0.03 LogMAR; p < 0.0001) and the fixation pattern improved, as demonstrated by microperimetry examination. Binocularly, stereopsis improved or emerged while suppression at the Worth four-dot test disappeared.

Conclusions

In the absence of further amblyopic factors such as coexisting constant vertical and/or horizontal deviation and anisometropia, the amblyopia encountered in congenital SO palsy may resolve soon after the surgical alignment. Therefore, it may be considered and defined “pseudoamblyopia.”