Comparison of Different Surgical Approaches to Inferior Oblique Overaction

Surgical Outcome of Inferior Oblique Myectomy versus Recession-Anteriorization in the Treatment of Inferior Oblique Overaction

Purpose

This study aimed to compare the surgical outcome of inferior oblique myectomy, IOM versus inferior oblique recession-anteriorization, IORA in the treatment of inferior oblique overaction, IOOA.

Patients and Methods

A retrospective chart review was performed over a 12-year period, from 2009 to 2021. Eighty-nine patients diagnosed with IOOA who underwent IOM or IORA were included. The primary outcome was postoperative residual IOOA (grade 0 to +4) and percentage favorable outcome, defined as IOOA grade ≤1+ at 6 months post operation, in each group. The outcomes were compared between the two surgical procedures (IOM and IORA). The secondary outcome was the percentage of postoperative anti-elevation syndrome cases for each surgical procedure.

Results

The median age at the time of surgery was 10.50 years (interquartile range, IQR: 2.83 to 28.33) in the IOM group and 5.08 years (IQR: 2.75 to 29.42) in the IORA group. The favorable outcome at 6 months was 90.91% in the IOM group, which was lower than the 95.74% in the IORA group but the difference was not statistically significant (P-value = 0.390, 95% CI: 0.07-2.82). The only surgical complication, anti-elevation syndrome, was detected in 3.77% of IOM cases and 5.80% of IORA cases, with an odds ratio of 0.64 on comparing the IOM group to the IORA group (P-value = 0.611, 95% CI: 0.11-3.62).

Conclusion

These two weakening procedures are effective for treating IOOA. Although IORA seemed slightly superior to IOM in terms of favorable outcomes, the difference was not statistically significant. Moreover, the myectomy procedure was easier, was less time-consuming, had a lower risk of globe perforation and presented fewer complications such as anti-elevation syndrome.

Effect of bilateral inferior oblique partial myectomy on V pattern exotropia with inferior oblique overaction

Purpose

To compare the effect of bilateral inferior oblique partial myectomy on V-pattern exotropia patients with bilateral symmetric inferior oblique overaction (IOOA) and asymmetric IOOA.

Methods

This was a retrospective study including 53 V-pattern exotropia patients with bilateral IOOA of all grades who underwent bilateral inferior oblique partial myectomy. Success was defined as the elimination of the IOOA and the collapse of the V pattern at the final follow-up. The fovea-disc angle (FDA) and V-pattern exotropia were compared before and after surgery.

Results

This study included 53 V-pattern exotropia patients, containing 29 patients with symmetric IOOA (Group I) and 24 patients with asymmetric IOOA (Group II). The last follow-up ranged from 3 to 16 months (mean of 5 months). After myectomy, 3 eyes in Group I and 2 eyes in Group II were observed with residual grade 1 IOOA. The surgical success rates of IOOA correction in Group I and Group II were 96% and 95%, respectively. The difference was not statistically significant (P = 0.808). V-pattern exotropia collapsed with residual 2 (min. 0, max. 6) PD for Group I and 2 (min. 0, max. 10) PD for Group II, and there was a statistically significant difference between pre- and postoperative V-pattern exotropia in the two groups (P = 0.000). No inferior oblique (IO) underaction or antielevation syndrome (AES) was found in either group. The average preoperative FDA of the right eye and the left eye was (8.93 ± 4.34)° and (10.86 ± 4.27)° in Group I and (9.08 ± 4.92)° and (11.00 ± 5.69)° in Group II. There was a significant difference in preoperative FDA between the right eye and the left eye in the two groups (Group I p = 0.029; Group II p = 0.038).

Conclusions

Bilateral inferior oblique partial myectomy can bring “symmetric” effectiveness in the correction of IOOA and FDA. It can potentially be used as a safe and successful treatment for V-pattern exotropia with bilateral IOOA. In addition, the FDA may be a promising index for evaluating fundus extorsion.

Inferior oblique anterior transposition according to a grading scale for hyperdeviation with inferior oblique overaction

OBJECTIVE

To define an inferior oblique anterior transposition (IOAT) grading scale in patients with hyperdeviation and inferior oblique overaction (IOOA), which we planned based on the data we obtained in our previous retrospective study.

DESIGN

Prospective cohort study.

PARTICIPANTS

Thirty-eight patients who underwent graded IOAT.

METHODS

The patients were divided into 5 groups according to the amount of hyperdeviation in the primary position (PPHD). The inferior oblique muscle was transposed 2 mm posterior, 1 mm posterior parallel, 1 mm anterior, and 2 mm anterior to the inferior rectus insertion, respectively. Surgical success was defined as success (PPHD ≤3 PD), partial success (PPHD >3 and ≤6 PD), and nonsuccess (PPHD >6 PD).

RESULTS

The mean amount of hyperdeviation correction in groups after IOAT was 9.50 ± 0.9 PD (range, 8-10 PD), 12.43 ± 1.5 PD (range, 11-14 PD), 16.67 ± 1.4 PD (range, 15-18 PD), 19.57 ± 1.7 PD (range, 16-21 PD), and 22.57 ± 5.8 PD (range, 14-30 PD), respectively. Surgical success was achieved in 34 patients (89.5%) after surgery, partial success was achieved in 3 patients (7.9%), and nonsuccess was observed in 1 patient (2.6%). All patients in our study had unilateral IOOA preoperatively, and IOOA developed in the contralateral eye of 9 patients (23.7%) during postoperative follow-up. In group 5, 4 patients (57.1%) developed -2 upgaze limitation, but surgery was not required.

CONCLUSIONS

A high success rate can be achieved with this grading of IOAT in primary and secondary IOOA cases accompanying hyperdeviation in the primary position.

Different Surgical Approaches for treatment of isolated dissociated vertical deviation without inferior oblique overaction

PURPOSE

To report the surgical results on superior rectus recession (SRR) and inferior oblique anterior transposition (IOAT) for cases with isolated bilateral dissociated vertical deviation（DVD）without inferior oblique overaction (IOOA).

METHODS

A retrospective review was conducted for cases with isolated bilateral DVD without IOOA who were surgically treated using either bilateral SRR (SRR group) or IOAT (IOAT group). Pre- and post-operative ocular motility, ocular alignment, amount of DVD and complications were compared between the two groups.

RESULTS

Records from 37 cases were reviewed. Preoperative levels of DVD (M ± SD) in the SRR group (N = 18) of 19.88 ± 6.72 prism diopter (PD) in the right eye and 19.54 ± 5.64 PD in the left eye, were reduced to 4.94 ± 7.26 PD and 4.11 ± 3.91 PD respectively after surgery (P＜0.0001 for both). Preoperative levels of DVD (M ± SD) in IOAT group (N = 19) of 15.89 ± 6.35 PD in the right eye and 18.58 ± 9.27 PD in the left eye, were reduced to 3.42 ± 4.49 PD and 3.42 ± 4.88 PD respectively after surgery (P＜0.0001 for both). Inferior oblique (IO) muscle function remained normal after surgery. Overall, outcomes within the SRR group revealed that 10 patients showed a complete resolution of their condition, 6 effective responses and 2 failures. In the IOAT group, 13 patients showed a complete resolution of their condition, 5 effective responses and 1 failure. There were no statistically significant differences between the two groups (Z = 0.48).

CONCLUSION

SRR and IOAT were both effective in treating isolated DVD without IOOA with similar satisfactory results obtained for both procedures.