Shipman 2003.

Methods	Study design: parallel‐group randomized controlled trial Number randomized: 24 total participants, 12 in the unilateral inferior oblique myectomy group and 12 in the unilateral inferior oblique recession group Exclusions after randomization: none reported Losses to follow‐up: 1 participant who underwent recession failed to complete 1‐year follow‐up Number analyzed: 23 total participants, 12 in the unilateral inferior oblique myectomy group and 11 in the unilateral inferior oblique recession group Unit of analysis: individual (1 study eye per participant) How were missing data handled? 1 participant missing 1‐year follow‐up excluded from analysis Power calculation: none reported
Participants	Country: UK Mean age: 30.8 years (range 12 to 77 years) in the myectomy group, 28.5 years (range 13.7 to 69 years) in the recession group Gender: not reported Inclusion criteria: symptom‐producing and/or socially noticeable unilateral overacting inferior oblique muscle Exclusion criteria: previous or simultaneous extraocular muscle surgery, strabismus surgery or prisms during follow‐up period, inability to co‐operate with testing, visual acuity of 20/60 or worse in either eye, failure to attend any postoperative visit Equivalence of baseline characteristics: preoperative median hypertropia in primary gaze was 15 PD and 10 PD in the myectomy and recession groups, respectively. Preoperative median hypertropia in contralateral gaze was 26.5 PD and 20 PD in the myectomy and recession groups, respectively. There was no statistically significant difference in hypertropia in contralateral gaze, inferior oblique overaction, or superior oblique underaction preoperatively between groups. Other participant details: all participants had decompensated longstanding unilateral superior oblique underaction, although this was not an inclusion criterion
Interventions	Intervention 1: unilateral inferior oblique myectomy at the temporal border of the inferior rectus muscle Intervention 2: unilateral inferior oblique 10‐millimeter recession (3 mm posterior and 2.5 mm lateral to the temporal pole of the inferior rectus muscle insertion) Length of follow‐up: 12 months
Outcomes	Main outcomes: average postoperative reduction of vertical deviation in ipsilateral, primary, and contralateral gaze positions; median postoperative hypertropia in ipsilateral, primary, and contralateral gaze positions; average change of vertical deviation in ipsilateral, primary, and contralateral gaze positions between 2 weeks and 12 months postoperatively; median postoperative reduction in inferior oblique muscle overaction; median postoperative improvement in superior oblique function Adverse events: none reported Intervals at which outcomes assessed: 2 weeks, 4 and 12 months postoperatively
Notes	Publication type: journal article Trial registration: not reported Study period: not reported Funding source: not reported Disclosures of interest: not reported Subgroup analyses: participants with preoperative primary position hypertropias of 15 PD or more, participants with preoperative hypertropias of 10 PD of more in ipsilateral gaze Contact with trial investigators: none
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method of randomization not reported.
Allocation concealment (selection bias)	Unclear risk	Method of allocation concealment not reported.
Masking of participants and personnel (performance bias)	Unclear risk	Surgeons could not be masked. Masking of participants not reported.
Masking of outcome assessment (detection bias)	Unclear risk	Measurements were performed by an orthoptist; masking of the orthoptist not reported.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	1 participant in the recession group withdrew from the study. The characteristics of this participant were not reported, other than indicating that this participant was "asymptomatic in the early postoperative period."
Selective reporting (reporting bias)	Unclear risk	The protocol was not available, so prespecified outcomes are unknown.
Other bias	Low risk	None identified.