Recession of Medial Rectus Muscle

Recession of the medial rectus is a measured retroplacement of the muscle from its original insertion. It is the easiest and most effective way of weakening the medial rectus and is the most commonly performed procedure in strabismus management. Its effect is maximal in its field of action and has a significant effect in primary position. Meticulous attention to detail leads to easier surgery, fewer complications, and more predictable outcomes.

The image below depicts one of the steps in recession of the medial rectus.

Medial rectus recession is the procedure of choice in esodeviation. It may be performed alone if the angle of deviation is small, ^{[1, 2, 3]} but the procedure is more commonly performed bilaterally in congenital or infantile esotropia. ^{[4, 5]} Medial rectus recession may also be performed in combination with a resection of 1 or both lateral recti when the amount of esotropia is too large. ^[6]

Medial rectus recession is the procedure of choice for restrictive strabismuslike thyroid-related eye disease. ^{[7, 8]} It may also be combined with other techniques such as the Faden operation ^{[9, 10]} and pulley posterior fixation ^{[11, 12]} for accommodative esotropia, Y splitting ^{[13, 14]} for convergence excess esotropia, vertical offset or transposition and slanting surgical techniques ^{[15, 16, 17, 18]} for pattern strabismus, and plication. ^{[19, 20, 21]} It can be an adjunct procedure to the medial rectus of the fellow eye in paresis or paralysis of a lateral rectus, ^{[22, 8]} and it may be used in combination with vertical rectus transposition in esotropic Duane syndrome. ^[23]

Purely refractive accommodative esotropia with normal accommodation convergence to accommodation (AC/A) ratio responds well to single-focus lenses and does not need medial rectus recession unless a nonaccommodative component also is present.

This procedure may be performed under local (topical, peribulbar, or retrobulbar) or general anesthesia in an adult but should be performed under general anesthesia in a child. The use of a laryngeal mask enables rapid recovery. Topical and limited local anesthesia may be given postoperatively.

Equipment should include a basic muscle surgery set with a good selection of muscle hooks, silk 5-0 stay suture, Vicryl 6-0 for muscle recession, and Vicryl 8-0 for conjunctival incision closure.

The patient is positioned such that the head is level and the neck is slightly extended for superior accessibility. The surgeon may position themself superiorly or temporally, ipsilateral to the muscle for recession. The skin within the surgical field should be scrubbed gently with aqueous povidone iodine. The eyebrows should be draped so they are not within the surgical field. The lashes are best covered with Tegaderm prior to application of a lid speculum.

Conjunctival incision

The conjunctival incision in strabismus surgery can be performed several ways. The classic Swan incision over the muscle is one option, but it is now rarely used due to its traumatic nature. The limbal incision gives the best exposure for the rectus muscle and can be conveniently combined with a conjunctival recession if necessary. Lastly, the fornix incision provides quick access and produces minimal scarring. However, it requires a good assistant and is not ideal for the older patient whose conjunctiva might tear easily when stretched. Several modifications of these 3 basic approaches have been made through the years to allow adjustable suturing technique. ^[24]

A limbal approach for right medial rectus recession is described below.

After carrying forced ductions, a silk 5-0 stay suture or Moody forceps is applied on the limbal area at 12 o’clock and 6 o’clock. The globe is then abducted to expose its medial aspect. An inferior radial incision is made, and blunt tipped Westcott scissors are used to undermine the anterior Tenon’s capsule and conjunctiva. Then, a limbal peritomy is performed over 4 o'clock hours. Finally, a second radial conjunctival incision is made above and parallel to the first incision.

Dissection and muscle hooking

The conjunctiva and Tenon’s capsule are grasped by a tissue forceps in the area of the inferior nasal fornix. The tissues are then pulled straight up to expose the inferonasal quadrant. The blunt Westcott scissors are closed, advanced along bare sclera into the inferonasal quadrant, and then spread to open a buttonhole under the intermuscular septum.

A pair of Lester forceps is placed at the inferior limbus to stabilize and abduct the eye, while the inferior nasal conjunctiva and Tenon’s capsule are grasped with 0.3 Castroviejo forceps and retracted to expose the inferonasal sclera. The inferior pole of the medial rectus is identified by the anterior ciliary artery. Under direct visualization of the inferior pole of the medial rectus muscle, a small Steven’s hook is placed perpendicular to sclera and passed behind the medial rectus muscle.

While the small Steven’s hook is under the medial rectus, a large Jameson hook is passed parallel to the muscle insertion line, keeping the tip of the hook down firmly against the sclera until the muscle hook has incorporated the entire width of the muscle. Then the superior nasal intermuscular septum is folded over the tip of the Jameson hook. Intermuscular septum is incised by grasping below the tip of the muscle hook with a Lester forceps and cutting between the forceps and the tip of the muscle hook.

Using the hole in the intermuscular septum in the superonasal quadrant, the superior pole of the medial rectus and the superior ciliary artery are visualized. The pole test can be performed by placing 2 small Steven’s hooks within the hole in the intermuscular septum and sweeping the anterior muscle hook toward the cornea around the muscle pole. ^[25] A positive pole test shows the muscle split, and the small hook will be unable to advance anteriorly.

The anterior Tenon’s capsule in front of the muscle is then removed with Westcott scissors. Light cautery is applied to the anterior ciliary vessels at this point.

Securing the muscle and disinsertion

After being cleared of anterior Tenon’s capsule, the Jameson hook is changed with a Chavasse muscle hook and the muscle is secured with a coated double-armed Vicryl 6-0 suture with an s-29 needle. The entire width of the tendon is imagined to be divided into 3 equal segments.

The needle is passed through a half-thickness tendon, through the central one-third of the width of the tendon, and exits on the point between the superior and central third of the tendon width. Then the needle is passed through a half-thickness tendon, through the superior half of the tendon width, and exits 1 mm above the sclera. Then the needled is passed through full-thickness tendon to incorporate 2 mm of the edge of the muscle, approximately 1 mm above the sclera.

A locking stitch with a twist is performed by passing the suture through the loop. The same procedure is performed with the other needle, along the inferior half of the muscle.

Once the muscle is secured, the preplaced sutures are pulled up gently, keeping them away from the sclera, by placing them between the thumb and index finger.

With direct visualization of the insertion, the inferior and superior edge of the insertion is marked with a sterile marking pen, and the muscle tendon is disinserted with Westcott scissors.

Recession and securing the muscle to the sclera at its new location

Described below is a medial rectus recession using Fells hangback technique. ^[26]

Before anchoring the muscle, the desired amount of recession is measured from the original insertion line or, more accurately, from the limbus using a calliper, and is marked by a sterile marking pen.

While securing the globe with a toothed forceps, a scleral pass is made through the superior edge of the original insertion, the needle angled to emerge 1 mm anterior to the middle of the line of insertion. Another scleral pass is made near the center of the insertion line. An identical set of 2 passes are made on the inferior end of the insertion. The muscle is pulled up to the level of the desired new insertion, making sure the sutures are taut and the muscle belly spreads nicely against the sclera.

One suture end is cut 3 cm from the sclera, and a knot is tied with a double forehand throw, a single backhand throw, and a final single forehand throw. The sutures are then cut 2 mm from the knot.

The above technique may also be modified by using an adjustable slipknot. ^[26]

Conjunctival closure

The conjunctiva is then closed with 2 interrupted Vicryl 8-0 sutures.

Know which conjunctival incision is best to use: Although fornix incision gives you access to the muscle quickest and leaves minimal scarring, it is contraindicated in patients older than 45 years due to the friability of their conjunctiva.

The key in hooking a muscle is to start with the hook perpendicular to the sclera, push posteriorly, and turn the corner behind the muscle.

Hemostasis makes surgery easier and reduces postoperative inflammation and adhesions. Any source of bleeding should be identified and cauterized prior to suture placement.

Careful blunt dissection enables good exposure, limits adhesion formation, and minimizes muscle and blood vessel trauma, as well as fat prolapse. Once the rectus muscle has been exposed, excessive Tenon’s tissue should be excised from its surface to allow accurate placement of sutures without snagging on the suture. Large dissections or cleaning of the intermuscular septum and checking ligaments more than 5 mm posterior to the insertion are not indicated and do not enhance the recession. In addition to being unnecessary, excessive dissection may disrupt the normal pulley anatomy. ^[27] Unlike the other rectus muscles, the medial rectus does not have any direct attachments on an adjacent oblique, making it more difficult to retrieve should it be lost at the time of surgery.

Suture placement prior to disinsertion should be 0.5-1 mm from the insertion with secure lock bites at both poles so the whole muscle is incorporated into the suture without any Tenon’s tissue. This minimizes the mount of induced resection and the muscle is secure on the suture and can be disinserted safely, reducing the risk for muscle slippage.

Saline irrigation avoids shrinkage of conjunctiva, sclerae, and muscle. A small amount of phenylephrine may be mixed with saline to constrict large vessels.

Whether using a single-ended or double-ended suture technique, careful suture placement with accurate knots reduces the risk of sutures looping and muscle slippage. A double-ended suture provides support for the center of the muscle and not just the poles and can be used for most muscle recession including the adjustable kind.

Use the limbus as a point of reference during recession: The advantage of measuring a recession from the limbus is that it is a fixed anatomic point, whereas the insertion, particularly that of the medial rectus, varies. ^{[28, 29]} The limbus can be up to 1.5 mm wide. If measurements are made from the insertion, it should be measured before the muscle is disinserted as it can creep toward the limbus after disinsertion. ^[30]

Recess the conjunctiva when tight. Conjunctival recession increases the effect of the recession only if the conjunctiva is tight and is causing restriction. In most pediatric cases, the conjunctiva isn't restricted, and recession is rarely needed. In older patients with long-standing large deviations, the conjunctivae may be tight, and conjunctival recession is indicated.

Complications of the recession of medial rectus muscle include the following:

• Slipped muscle

• Lost muscle

• Split muscle

• Central muscle sag

• Under/overcorrection

• Severe adduction deficiency