OBJECTIVE: The objective of this study was to compare the effects of horizontal muscle transposition and inferior oblique weakening combined with horizontal surgery performed for V-pattern exotropia (XT) and to determine the most successful approach.
METHODS: In our retrospective study, 52 patients who underwent horizontal surgery due to V-pattern XT and were followed up for at least 6 months were divided into two groups. Group 1 (n = 26) consisted of patients who underwent vertical transposition of the rectus muscles combined with horizontal surgery, and group 2 (n = 26) consisted of patients who underwent inferior oblique weakening combined with horizontal surgery. The two groups were compared before and after surgery in terms of visual acuity, refractive errors, deviation angles, pattern strabismus, fusion, stereopsis, over/under correction and surgical success.
RESULTS: There was no difference between the two groups in terms of age, follow-up period, visual acuity, refractive errors, fusion or stereopsis. The amount of horizontal deviation was smaller in group 2 at the 1-6-month follow-ups. There was no difference between the two groups in terms of pattern collapse; however, the amount of pattern postoperatively was lower in group 2. The two groups were similar in terms of overcorrection; however, the undercorrection rate was higher in group 1. The surgical success rate was higher in group 2.
CONCLUSIONS: Inferior oblique weakening combined with horizontal surgery due to V-pattern XT was found to be superior to vertical transposition of the horizontal muscles in terms of surgical success and the amount of pattern postoperatively.

OBJECTIVE: To evaluate outcomes of botulinum toxin (BTX) injection of the inferior oblique (IO) muscle.
METHODS: Retrospective case series.
METHODS: Setting: Single center, ophthalmology department at Boston Children\'s Hospital.
METHODS: All patients treated with IO muscle injection of BTX (onabotulinumtoxinA) between 2010 and 2020.
METHODS: Sensorimotor evaluations at short-term (<2 months), medium-term (2-4 months), and long-term (≥4 months) intervals.
METHODS: Primary outcomes included median improvement in V-pattern strabismus and primary position hypertropia. Secondary outcomes included IO muscle overaction. Wilcoxon signed-rank tests were performed to identify differences before and after injection.
RESULTS: Record review identified 20 patients with a median age of 4.5 (range, 1-69) years. Median BTX dose injected (31 IO muscles) was 5.0 (range, 3.0-7.0) units. Indications included V-pattern strabismus (N = 8), hypertropia (N = 7), or both (N = 5). Median long-term interval was 6.4 (range, 4.1-26.6) months. Injections were concurrent with treatment of horizontal strabismus in all but 3 cases. Median V-pattern magnitude changed from 10 prism diopters (PD) preoperatively to 0 PD short-term (P = .006) and 3.5 PD long-term (P = .34). Median hypertropia changed from 8.5 PD preoperatively to 1.5 PD short-term (P = .01) and 8 PD long-term (P = .87). Median IO muscle overaction grade improved significantly at short-term (P < .001) and long-term (P = .007) intervals. There were no complications associated with the IO muscle injections.
CONCLUSIONS: BTX injection of the IO muscles can be a useful adjunct to the management of V-pattern strabismus. Intervention for primary position hypertropia may be helpful for short-term relief with no expectation of long-term benefit.

OBJECTIVE: To compare outcomes of conventional and Hang-back methods of inferior oblique (IO) recession in V-pattern strabismus with inferior oblique overaction (IOOA).
METHODS: Comparative randomized study was conducted consisting of 50 patients, age 6 to 35y having V-pattern strabismus [>15 prism diopter (PD)] with IOOA. They were divided equally in two groups and underwent IO recession, group A by conventional method and group B by Hang-back method. Parameters evaluated were reduction in V-pattern and IOOA, shift in torsion, improvement in binocular status. Success was a residual V-pattern of less than 10 PD at 1y of follow up.
RESULTS: The mean V-pattern preoperatively and postoperatively at 1y was 24±5.4 PD and 4.2±3.51 PD in group A and 23.44±6.44 PD and 5.76±3.8 PD in group B respectively. The mean reduction in V-pattern was 20±6.78 PD in group A and 18.2±5.48 PD in group B. The mean correction of IOOA was 18.48±3.13 PD in group A and 16±2.93 PD in group B. Mean shift in extorsion was 3.08±1.8 degree in group A and 3.72±2.14 degree in group B.
CONCLUSIONS: Both the procedures achieve a significant and comparable reduction in V-pattern and IOOA. Hang-back recession being a landmark free surgery eliminates the need for intrascleral suturing thereby reducing the risk of scleral perforation with possible postoperative adjustment of muscle. It may be considered as a good alternative for IO recession in patients of V-pattern strabismus with mild to moderate amount of IOOA.

OBJECTIVE: To compare the effectiveness of inferior oblique retroequatorial myopexy and inferior oblique myectomy in correction of inferior oblique overaction (IOOA).
METHODS: This was a pilot study study including forty patients with primary IOOA of all grades, with or without primary position horizontal deviations. Patients were randomized to have either IO retroequatorial myopexy, group A, or IO myectomy, group B. Success was defined as elimination of the IOOA at 6 months postoperatively. Secondary outcome measures included residual or recurrent elevation in adduction, development of postoperative hypotropia in adduction, postoperative contralateral IOOA, major intraoperative complications, and reversibility of the procedure.
RESULTS: At 6 months postoperative, the success rate was higher in the myectomy group (76%) than in the myopexy group (58%); however, this difference was not statistically significant (P = 0.1). The incidence of residual IOOA in myopexy group was significantly higher in patients with higher preoperative grades of IOOA (P ˂ 0.001). While this difference was not statistically significant among patients in myectomy group (P = 0.09). Collapse of V-pattern was acheived in nine (69%) patients in myopexy group compared with 8 (57%) in myectomy group with a statistically significant difference (P ≤ 0.001). No patients in myopexy group developed postoperative hypotropia in adduction or postoperative contralateral IOOA, compared with eight (22%) patients of myectomy group (P = 0.002) who developed postoperative hypotropia and two (66.6%) patients with unilateral IOOA who developed contralateral IOOA in myectomy group (P ˂ 0.001). No intraoperative complications were encountered in either group. postoperative.
CONCLUSIONS: Retroequatorial myopexy of the inferior oblique is as effective as inferior oblique myectomy in eliminating lower and moderate grades of primary IOOA; however, it is more effective in collapsing V-pattern associated with IOOA, and is not associated with postoperative hypotropia or contralateral IOOA after unilateral surgery. It can be used as a safe, reversible alternative to myectomy; however, it is not suitable for high grades of IOOA.