Medial rectus recession — primary surgeon's view · Rectus Muscle Surgery Fundamentals

The video shows the single-armed technique: each pole gets its own suture, its own short scleral pass and its own knot.

Key steps

Fan the isolated, cleaned muscle out on the hook and secure each pole with its own single-armed 6-0 Vicryl. Start at the muscle border about 1 mm behind the insertion and pass partial-thickness out through the muscle surface, taking about a third of the tendon width and any ciliary vessel on that side. Then take a full-thickness locking bite of the outer 1–2 mm of the border, bringing the needle back through the loop to lock. Cinch it, clamp it with a serrefine, and repeat at the other pole.
Three things decide whether those sutures hold: no part of a suture may run through superficial sclera where disinsertion will cut it; the locking bite must be full thickness, because a capsule-only bite is how muscles slip; and it should grab no more than 1–2 mm of margin, or the tendon bunches and the new insertion narrows.
Disinsert with blunt scissors, controlling globe, insertion and sutures at once. Keep slightly more tension on the sutures than on the muscle, so the suture lifts off sclera — if one is cut you feel that pole go slack immediately and can replace it before the muscle is free.
Through a fornix wound, start disinserting at the pole away from the incision and grab that stump pole with a locking forceps as soon as it is free, then the second. The two forceps then mark the original insertion, position the globe and retract conjunctiva.
Reattach the pole farthest from the incision first. Measure its scleral entry point with calipers on a line perpendicular to the original insertion, pressing 5–10 seconds to leave a visible mark, then rotate that mark into the center of the field.
Take a partial-thickness scleral bite at the mark, in whichever direction is comfortable, with the needle holder parallel to sclera and the needle visible through sclera the whole way. Keep the tunnel short, about 2 mm — a long tunnel lets the first throw loosen.
Pull both ends of the suture parallel to the tunnel to seat the pole, keeping Tenon’s out of the track, and tie: a double throw, then two single throws. Cut the ends long enough that the knot cannot untie itself.
Now use the second pole’s suture to pull the muscle out to its full width, and judge where the second bite has to go to fan the insertion out completely. Caliper that point back from the original insertion and repeat steps 6 and 7.
Inspect: both poles tight, the new insertion directly behind the old one, the same width, no central sag. Verify with calipers at both poles and the center.

Why single-armed. Both scleral passes can be forehand, the tunnels are short rather than long and crossed — easier and arguably safer when exposure is poor — and you choose the second bite after the first pole is down, so you can set the width of the new insertion exactly. The price is more suture in the field, two knots instead of one, and knots tied close to the muscle, where tendon or capsule can get caught. It cannot be used for an adjustable or a hang-back recession; those need the double-armed, crossed-swords pass shown in the adjustable-suture lesson.

Sequencing on a multi-procedure eye: obliques first, then large hang-back recessions, then standard recessions, superior oblique tuck, and resections last. Recession before resection on the same eye — the recession is easier and it slackens the globe for the harder procedure.

Pearl: The medial rectus is the one rectus muscle with no oblique beside it. When Plager and Parks reviewed 25 lost muscles, the ones they got back were found largely through their connections to a neighboring oblique. The medial rectus has none, so once it is free and unsutured it retracts straight back into the orbit. Feel the pole sutures the whole time you are cutting, and if a pole goes slack, stop, hold what is already free with a locking forceps, and put a fresh suture into that pole before you cut any further.

Pearl: The recession is only the number you measured if the new insertion is as wide as the old one. Let it narrow and the center sags back further than the poles, so the patient gets more recession than you wrote down. This is what the single-armed technique is good at: with the first pole tied, stretch the muscle to full width on the second suture before you choose the second bite. Measure each pole along a line dropped at right angles from the original insertion, and caliper the center as well as the poles.

Pearl: The sclera just behind a rectus insertion is the thinnest on the globe, about 0.3 mm, and that is exactly where a recession needle goes. Published perforation rates run from 3 in 1,000 to nearly 8%, with rectus recession the most consistently named risk factor. If you cannot see the needle through sclera you are too deep: back it out and start the pass again. If you think you went through, say so, and look at the retina under that pass before the patient leaves the room.

Pitfalls to avoid

A capsule-only locking bite: the muscle slips days later.
Suture through superficial sclera where you are about to cut.
Central sag or a narrowed insertion, which is easy to prevent when you place the second pole and annoying to fix once it is tied.
A long scleral tunnel, which lets the first throw loosen.
Tendon, capsule or Tenon’s caught in a knot tied close to the muscle.
Cranking the globe around on a muscle already under resection tension.

Key steps

Pitfalls to avoid

Further reading