Postoperative Adjustable Surgery of the Superior Oblique Tendon

Adjustable Sutures in the Treatment of Strabismus: A Report by the American Academy of Ophthalmology

PURPOSE

To review the scientific literature that evaluates the effectiveness of adjustable sutures in the management of strabismus for adult and pediatric patients.

METHODS

Literature searches were performed in the PubMed database through April 2021 with no date limitations and were restricted to publications in English. The searches identified 551 relevant citations, of which 55 were reviewed in full text. Of these, 17 articles met the inclusion criteria and were assigned a level of evidence rating by the panel methodologist. The search included all randomized controlled studies regardless of study size and cohort studies of 100 or more patients comparing the adjustable versus nonadjustable suture technique, with a focus on motor alignment outcomes or reoperation rates.

RESULTS

The literature search yielded no level I studies. Of the 17 articles that met the inclusion criteria, 11 were rated level II and 6 were rated level III. Among the 12 studies that focused on motor alignment outcomes, 4 small randomized clinical trials (RCTs) did not find a statistically significant difference between groups, although they were powered to detect only very large differences. Seven of 8 nonrandomized studies found a statistically significant difference in motor alignment success in favor of the adjustable suture technique, both overall and in certain subgroups of patients. Successful motor alignment was seen in both exotropia (in 3 studies that were not limited to children) and esotropia (in 1 study of adults and 2 of children). The majority of included studies that reported on reoperation rates found the rates to be lower in patients who underwent strabismus surgery with adjustable sutures, but this finding was not uniformly demonstrated.

CONCLUSIONS

Although there are no level I studies evaluating the effectiveness of adjustable sutures for strabismus surgery, the majority of nonrandomized studies that met the inclusion criteria for this assessment reported an advantage of the adjustable suture technique over the nonadjustable technique with respect to motor alignment outcomes. This finding was not uniformly demonstrated among all studies reviewed and warrants further investigation in the development and analysis of adjustable suture techniques.

Adjustable Versus Nonadjustable Sutures in Strabismus Surgery-Who Benefits the Most?

BACKGROUND

Adjustable sutures have been used in strabismus surgery for more than 40 years, but controversy remains regarding their application. This review sought to analyze studies comparing the efficacy of adjustable sutures (AS) and nonadjustable sutures (NAS) in the treatment of different ocular deviations.

MATERIALS AND METHODS

The PubMed literature database was searched using the keywords 'adjustable sutures' and 'strabismus surgery', yielding a total of 209 results. Only comparative studies were extracted, and the results were divided into three categories: Adult comitant strabismus, childhood comitant strabismus, and paretic/restrictive strabismus.

RESULTS

The search revealed eleven comparative studies on AS versus NAS in adult strabismus, including only one randomized controlled trial. Five of these studies analyzed just the postoperative success rate, three studies analyzed just the reoperation rate, two studies analyzed both the postoperative success and reoperation rates, and one study evaluated achievement of the postoperative target angle. Three of seven studies analyzing postoperative success reported the statically significant superiority of AS over NAS, while four of five studies analyzing reoperation rate indicated a significantly smaller percentage of reoperations with the use of AS. The study covering postoperative target angle as an outcome favored the AS technique. Separately, the search revealed three comparative studies on AS versus NAS in childhood strabismus, one of which reported a statistically significant advantage with AS. Only four comparative studies on AS versus NAS in paretic or restrictive strabismus were found; all showed a tendency for better results with the use of AS but not in a statistically significant fashion. Overall, out of 18 studies analyzed in this review, 17 suggested better clinical results followed the application of AS versus NAS; however, only a minority had statistically significant results.

CONCLUSION

The analysis of available research failed to support AS as the preferable surgery technique over NAS in cases of simple and predictive strabismus. Further research is needed to more precisely determine the group of patients able to benefit the most from AS.

[Brown's atavistic superior oblique syndrome: etiology of different types of motility disorders in congenital Brown's syndrome]

CLINICAL FEATURES

The congenital Brown syndrome is characterized by a mechanical limitation of elevation in adduction, with an orthophoria in down gaze. Brown postulated a shortened superior oblique tendon sheath as the cause of the limitation but this was disproved by Parks et al. in 1975 and the origin of Brown syndrome remains unclear. In recent years, a congenital dysinnervation has been discussed; however, this does not explain the full spectrum of abnormalities and especially contradicts the unlimited depression in adduction seen in Brown syndrome.

ORIGIN

Surgical exploration in Brown true typical cases reveals a fibrotic strand, typically located at the posterior margin of the superior oblique tendon. This strand originates from the trochlear area and has a common insertion with the superior oblique tendon posterior to the equator into the globe. It may represent an atavistic superior oblique muscle as described by Fink in various animals. They do not have a trochlea but a superior oblique muscle originating in the anterior superior nasal orbit.

ATYPICAL BROWN SYNDROME

A fibrotic strand was also surgically revealed in two cases of atypical Brown syndrome. In the first case an elevation deficit-as in Brown true atypical cases-also present in abduction could be explained by an unusual insertion of the fibrotic strand anterior to the equator. The second case showed a fibrotic strand which was completely separated from the superior oblique tendon and inserted far posterior to the equator nasal to the superior rectus muscle. This finding had not been previously described and explained the total elevation restriction which was suddenly in > 30° adduction and the Y‑pattern exotropia which increased in adduction and decreased in abduction.

TREATMENT AND FOLLOW-UP

A 10 mm excision of the fibrotic strand from the insertion gives the best results from all procedures. The residual limitation of active elevation in adduction improved with gaze exercises mostly after more than 1 year.

CONCLUSION

The fibrotic strand, an atavistic superior oblique muscle, not only explains the typical Brown syndrome but also-by its variable insertion-different patterns of elevation deficits seen in atypical Brown syndrome. A 10 mm excision of the strand gives good functional results of abnormal head position (immediate in most cases) and even elevation in adduction (after 1 year in most cases).

Consecutive superior oblique palsy after adjustable suture spacer surgery for Brown syndrome: incidence and predicting risk

PURPOSE

To determine the incidence of and to identify characteristics predicting significant superior oblique palsy (SOP) after adjustable superior oblique suture spacer surgery for treatment of Brown syndrome.

METHODS

The medical records of patients treated for unilateral Brown syndrome with adjustable suture spacers (2005-2016) were reviewed to identify possible association of age at surgery, spacer length, surgeon performing procedure, severity of Brown syndrome, preoperative hypotropia in primary position and affected side gaze, and reduction in Brown restriction on postoperative superior oblique function. "Good" postoperative superior oblique function was defined as absence of hypertropia and diplopia in primary position and no more than intermittent diplopia in downgaze comfortably fused with ≤4^Δ base-down or head tilt of <10°. Presence of postoperative hypertropia in primary position with increase in downgaze met criteria for significant SOP. Postoperative Brown restriction of ≤ -2 indicated resolution of Brown syndrome.

RESULTS

Median age at surgery was 59 months, interquartile range (IQR) was 32-82 months, and median spacer length was 6 mm (range, 2-7 mm) for 19 included patients. Preoperative median hypotropia was 9^Δ (IQR, 0^Δ-12^Δ) in primary position and 18^Δ (IQR, 5^Δ-22^Δ) in affected side gaze. Of 19 patients, 16 (84%) achieved sufficient resolution of Brown syndrome, but 6 (32%) developed significant SOP. Modest preoperative hypotropia in affected side gaze was the only predictor of significant SOP (likelihood ratio test = 7.11; P = 0.008). Logistic regression modeling enabled estimation of risk of significant SOP based on preoperative side gaze hypotropia.

CONCLUSIONS

Suture spacer surgery can result in significant SOP. Risk may be predicted by magnitude of preoperative side gaze hypotropia.

Adjustable Bilateral Superior Oblique Tendon Advancement for Bilateral Fourth Nerve Palsy

PURPOSE

Bilateral fourth nerve palsy may be symmetric or asymmetric with combined vertical and excylotropic deviations and so there may be an advantage to independent adjustment of vertical and torsional components. We report a surgical technique that allows such independent adjustment.

DESIGN

Retrospective interventional case series.

METHODS

Fifteen patients, aged 17-73 years, underwent adjustable bilateral superior oblique tendon advancements for bilateral fourth nerve palsy: 11 symmetric (≤2 prism diopters [pd] hyperdeviation in straight-ahead gaze) and 4 asymmetric. Motor alignment was assessed with double Maddox rods and prism and alternate cover tests preoperatively, pre- and postadjustment, and 6 weeks postoperatively.

RESULTS

Preoperative torsion ranged from 7 to 30 degrees excyclotropia (mean 17 ± 7 degrees) and hyperdeviation from 0 to 10 pd. Preadjustment torsion ranged from 5 degrees excyclotropia to 40 degrees incyclotropia, and hyperdeviation from 0 to 8 pd. Twelve of the 15 patients (80%) were adjusted to a target of 0 pd hyperphoria and 10 degrees incyclotropia (actual mean 9 degrees incyclotropia, range 2-13 degrees incyclotropia). At 6 weeks postoperatively there was expected excyclodrift (to mean 4 degrees excyclotropia, range 0 degrees incyclotropia to 15 degrees excyclotropia), but 13 (87%) had 5 degrees or less excyclotropia and 14 (93%) had 2 pd or less hyperdeviation. Mean torsional correction from preoperative to preadjustment was 31 ± 14 degrees (P < .0001), and from preoperative to 6 weeks was 13 ± 6 degrees (P < .0001).

CONCLUSIONS

Adjustable bilateral superior oblique tendon advancement allows independent control of torsional and vertical components of the deviation, and therefore may be useful in cases of bilateral superior oblique palsy.

Adjustable sutures in children

Although adjustable sutures are considered a standard technique in adult strabismus surgery, most surgeons are hesitant to attempt the technique in children, who are believed to be unlikely to cooperate for postoperative assessment and adjustment. Interest in using adjustable sutures in pediatric patients has increased with the development of surgical techniques specific to infants and children. This workshop briefly reviews the literature supporting the use of adjustable sutures in children and presents the approaches currently used by three experienced strabismus surgeons.

Superior oblique surgery: when and how?

BACKGROUND

The purpose of this paper is to review different types of superior oblique muscle surgeries, to describe the main areas in clinical practice where superior oblique surgery is required or preferred, and to discuss the preferred types of superior oblique surgery with respect to their clinical outcomes.

METHODS

A consecutive nonrandomized retrospective series of patients who had undergone superior oblique muscle surgery as a single procedure were enrolled in the study. The diagnosis, clinical features, preoperative and postoperative vertical deviations in primary position, type of surgery, complications, and clinical outcomes were reviewed. The primary outcome measures were the type of strabismus and the type of superior oblique muscle surgery. The secondary outcome measure was the results of the surgeries.

RESULTS

The review identified 40 (20 male, 20 female) patients with a median age of 6 (2-45) years. Nineteen patients (47.5%) had Brown syndrome, eleven (27.5%) had fourth nerve palsy, and ten (25.0%) had horizontal deviations with A pattern. The most commonly performed surgery was superior oblique tenotomy in 29 (72.5%) patients followed by superior oblique tuck in eleven (27.5%) patients. The amount of vertical deviation in the fourth nerve palsy and Brown syndrome groups (P = 0.01 for both) and the amount of A pattern in the A pattern group were significantly reduced postoperatively (P = 0.02).

CONCLUSION

Surgery for the superior oblique muscle requires experience and appropriate preoperative evaluation in view of its challenging nature. The main indications are Brown syndrome, fourth nerve palsy, and A pattern deviations. Superior oblique surgery may be effective in terms of pattern collapse and correction of vertical deviations in primary position.

Comparison of superior oblique suture spacers and superior oblique silicone band expanders

PURPOSE

To compare suture spacers with silicone band expanders in superior oblique-weakening surgery.

METHODS

We retrospectively reviewed the charts of consecutive patients who had superior oblique weakening with either suture spacers or silicone expanders and had been followed for a minimum follow-up of 6 months. The ductions, versions, and the degree of fundus torsion were analyzed in all patients before and after surgery. In addition, surgery time and postoperative complications were analyzed.

RESULTS

The record review identified 25 patients, of whom 13 had been treated with superior oblique muscle suture spacers and 12 with superior oblique muscle silicone expanders. Both groups showed improved ductions and versions. In patients with Brown syndrome, complete normalization of superior oblique muscle overaction occurred in 67% of patients who had suture spacers and 67% of patients who had silicone expanders. In patients with A-pattern strabismus, normal function of the superior oblique muscle occurred in 75% of patients with suture spacers and 67% of patients with silicone expanders. Surgery time was significantly less in patients who had suture spacers. Severe orbital inflammation occurred in 1 patient around the silicone band and was managed by removal of the implant.

CONCLUSIONS

Both suture spacers and silicone expanders improved the comitance of versions and normalized superior oblique muscle function. Longer surgery time and more severe inflammatory reaction are possible drawbacks of silicone expanders.

Adjustable suture strabismus surgery

Surgical management of strabismus remains a challenge because surgical success rates, short-term and long-term, are not ideal. Adjustable suture strabismus surgery has been available for decades as a tool to potentially enhance the surgical outcomes. Intellectually, it seems logical that having a second chance to improve the outcome of a strabismus procedure should increase the overall success rate and reduce the reoperation rate. Yet, adjustable suture surgery has not gained universal acceptance, partly because Level 1 evidence of its advantages is lacking, and partly because the learning curve for accurate decision making during suture adjustment may span a decade or more. In this review we describe the indications, techniques, and published results of adjustable suture surgery. We will discuss the option of 'no adjustment' in cases with satisfactory alignment with emphasis on recent advances allowing for delayed adjustment. The use of adjustable sutures in special circumstances will also be reviewed. Consistently improved outcomes in the adjustable arm of nearly all retrospective studies support the advantage of the adjustable option, and strabismus surgeons are advised to become facile in the application of this approach.

Horizontal mattress technique for superior oblique suture spacer

Superior oblique tendon overaction and Brown syndrome have been managed surgically by means of tenotomy/tenectomy, use of a silicon expander, and elongation with autologous fascia lata. These solutions are problematic with respect to corrective precision, injury and complications, or surgical difficulty. We present a simple "mattress" suture spacer technique that allows a precise and secure intraoperative adjustment.

Superior oblique tendon spacer with application of nonabsorbable adjustable suture for treatment of Brown syndrome

PURPOSE

To evaluate the outcomes of a superior oblique tendon spacer procedure using nonabsorbable adjustable sutures in patients with Brown syndrome.

METHODS

This noncomparative interventional case series includes 25 eyes of 25 patients with Brown syndrome. In all patients the superior oblique tendon was exposed; two nonabsorbable polyester sutures were placed 4 mm apart, and the tendon was cut. With the use of a slipknot, the cut ends of the tendon were separated 5 to 8 mm. Tendon separation was adjusted intraoperatively according to the exaggerated traction test and indirect ophthalmoscopy.

RESULTS

Overall 25 eyes of 25 patients with mean age of 8.00 +/- 4.62 years were operated and followed for a mean period of 13.2 +/- 7.6 months (range, 3 to 30 months). Mean elevation in adduction improved from -3.96 before surgery to -0.67 (p < 0.001); mean hypotropia improved from 11.08(Delta) to 0.32(Delta) (p < 0.001). Two patients developed overcorrection, but recurrence was not observed in any case. The patients continued to improve over the follow-up period.

CONCLUSIONS

The adjustable superior oblique tendon suture spacer procedure has favorable results and seems to be technically easier than a silicone expander procedure for Brown syndrome.