A 5-year-old child has an esotropia that increases markedly in downgaze, giving a V pattern of more than 25 prism diopters difference between upgaze and downgaze. Overaction of both inferior obliques is noted. Along with horizontal muscle surgery, the appropriate additional step is:

• A Superior oblique tucking
• B Horizontal transposition of the rectus insertions vertically
• C Weakening of both inferior oblique muscles ✓
• D Posterior fixation sutures on both superior recti

Explanation

A V-pattern esotropia is most commonly caused by bilateral inferior oblique overaction, which adds abduction in upgaze and narrows the angle down below. When significant inferior oblique overaction accompanies the V pattern, weakening procedures such as inferior oblique myectomy or graded recession performed together with the horizontal surgery corrects the pattern. Vertical transposition of horizontal recti is used for pattern strabismus without oblique overaction, and superior oblique tucking would aggravate an A pattern rather than a V pattern.

Reference: Kanski's Clinical Ophthalmology, 9th ed.

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Written and medically reviewed by the StethoPrep medical team.