Session: Poster session B

Is inferior oblique weakening effective in contralateral downgaze?

Introduction - Inferior oblique (IO) weakening procedures are utilised to correct hypertropia following primary or secondary IO overaction. Although effective in primary and contralateral upgaze, the effect of IO weakening on downgaze remains uncertain. This study aimed to look at the differential impact of IO weakening on version, elevation and depression in contralateral gaze.



Methods - We collected data from all patients who underwent isolated IO weakening procedures at a tertiary teaching hospital from 2012 - 2023. All patients had a pre-operative and post-operative 9 gaze deviation assessment. Data collection included the patient's age, type of procedure, the indication for surgery and the duration of follow-up. 



Results - We reviewed 35 patients who underwent IO weakening procedures. (24 left vs. 11 right). The procedures performed included recession (n=19), myectomy (n=8), anterior transposition (n=5), and tenotomy (n=3). We found that IO weakening procedures produced a mean correction of 7.4 Δ in primary position and 13.5, 13.6, and 12.1 Δ in contralateral version, elevation and depression respectively. All procedures reduced deviation in contralateral gaze. There was an average follow-up time of 4 months.



Conclusions - IO weakening procedures effectively reduced contralateral gaze deviation in all directions, but the impact was higher in upgaze compared to downgaze. This information is useful for deciding on the best surgical outcome in these cases and those with a larger deviation in downgaze may need a supplementary or alternative procedure to control their symptoms.