Definition

• Hang back procedure is a muscle weakening procedure.
• It is used as an alternative to muscle recession in esotropia, exotropia and others.

Surgical technique

• A limbal incision is made in a routine fashion.
• The muscle is hooked and the intermuscular septa and the anterior Tenon’s capsule are removed from in front of the muscle, so the sclera is bare.
• A 5.0 coated vicryl double-armed suture with spatulated needles is used to secure the muscle.
• The muscle is disinserted using scissors leaving a 1 mm stump of tendon.
• Spatula needles from the double armed suture are passed perpendicular to the scleral stump slightly into the sclera. The sutures are pulled forward so the muscle is drawn anteriorly to touch the scleral insertion.
• A needle holder is clamped across the 2 sutures approximately 6-7 mm of the sclera.
• Accurate measurement of the amount of muscle recession = length of hang back suture, is measured from the suture site in the detached muscle till the anterior edge of the needle holder grasping the sutures.
• The 2 sutures are tied together in a square knot over the needle holder (called pole suture).
• The muscle can be advanced or recessed by pulling or releasing the pole sutures.
• Re-measure the amount of muscle recession by leaving the muscle to recede back and rotating the eye away from the recessed muscle until stopped by the knot and measuring with caliper the actual recession.

Advantages of this technique and uses

• No scleral traumatization or perforation. Can be used safely in congenital esotropia surgery where the sclera is too thin under MR.
• Can be used for obtaining a large recession in some cases as incomitant strabismus and DRS.
• Can be modified for performing an adjustable suture technique by modifying the suture (releasable suture) to be re-adjusted in the following day.

Figure #1 Hang back technique

Figure #2 Hang back technique in exotropia

Figure #3 Hang back technique in exotropia

Cogenital Fibrosis syndrome , preop