Changes in the axis of astigmatism and in fundus torsion following inferior oblique muscle weakening

Comparison of excyclotorsion following graded inferior oblique recession for primary versus secondary inferior oblique overaction

AIM

To compare the changes in excyclotorsion after inferior oblique (IO) recession in patients with primary and secondary inferior oblique overaction (IOOA).

METHODS

We retrospectively analyzed the data obtained from patients with IOOA who underwent graded IO recession. The patients were followed up for at least 3mo after surgery. Fundus photographs were taken pre- and postoperatively, and the sum of the angles of torsion in both eyes was used to analyze changes in excyclotorsion. Patients were divided into two groups: those diagnosed with primary IOOA were enrolled in the 1'IOOA group, and those diagnosed with secondary IOOA caused by superior oblique palsy (SOP) were enrolled in the 2'IOOA group. Excyclotorsion before and after surgery were compared between the two groups.

RESULTS

A total of 78 patients were enrolled in this study: 34 eyes in the 1'IOOA group and 44 eyes in the 2'IOOA group. In the 78 patients, torsional angle significantly decreased from 15.31°±7.40° to 12.11°±6.53° after IO recession (P<0.001). Mean preoperative torsional angle was larger in the 2'IOOA group than in the 1'IOOA group (P=0.03). In both groups, excyclotorsion significantly decreased after IO recession (P=0.001 and P<0.001, respectively); however, there was no significant difference in the amounts of changes in excyclotorsion between the two groups.

CONCLUSION

Excyclotorsion is significantly larger in secondary IOOA than in primary IOOA, and a significant decrease in the torsional angle occurs after IO recession in both types of IOOA.

Torsional Changes After Vertical Transposition of Horizontal Recti in V-pattern Exotropia Without Oblique Dysfunction

PURPOSE

To evaluate pattern collapse and torsional changes following vertical transposition of horizontal recti in patients with V-pattern exotropia and no oblique dysfunction.

METHODS

A prospective study was performed on patients who had V-pattern exotropia and no oblique dysfunction. Lateral recti were transposed upward half-tendon width in V-pattern of 25 prism diopters (PD) or less (n = 14) and full-tendon width in V-pattern of greater than 25 PD (n = 10). Amblyopic patients had unilateral lateral rectus recession with upward transposition and medial rectus resection with downward transposition (n = 8). Ductions, versions, pattern strabismus, disc foveal angle, and astigmatic axis were analyzed before and 6 months after surgery.

RESULTS

In the 32 patients (21 females), the mean age was 8.25 ± 1.23 years. Only amblyopic patients showed preoperative fundus extorsion (mean disc foveal angle = 16.9°, P < .01). Mean pattern collapse was 13.1 ± 3.8 PD with half-tendon transposition, 35.6 ± 13.7 PD with full-tendon transposition, and 13.8 ± 7.9 PD in the unilateral group. Pattern collapse increased gradually so that pattern normalization occurred after 6 months in most patients. There was a statistically significant correlation between the preoperative V-pattern and the magnitude of pattern collapse after surgery (r = 0.80, P < .01). There were no significant changes in the mean disc foveal angle (< 0.5°) or axis of astigmatism (< 0.5°) in all three groups.

CONCLUSIONS

Vertical transposition of horizontal muscles can correct V-pattern exotropia, although the effect might not be immediate. Torsional changes are minimal. Amblyopic patients with V-pattern exotropia showed a preoperative extorsion that did not change after surgery. [J Pediatr Ophthalmol Strabismus. 2019;56(2):107-115.].