Recession of the medial rectus muscle is the most commonly performed extraocular muscle surgical procedure. This may be done alone but is more commonly employed in a bimedial rectus recession for treatment of esotropia. Medial rectus recession is also frequently combined with resection of one or both lateral recti and with strengthening or weakening of another extraocular muscle when an esodeviation is part of the clinical picture. While this procedure is common, specific techniques employed by different surgeons vary considerably. These variations notwithstanding, surgeons can achieve consistent effect by monitoring results. This, of course, favors the busier surgeon who has the opportunity to make minor adjustments in technique based on several surgical outcomes. Over the course of more than 30 years as a surgeon performing thousands of strabismus operations, I have arrived at a technique for recession of the medial rectus muscle which is easy to perform consistently, is effective, and which allows easy reoperation when this is necessary. The technique is not entirely new, being a modification of the cul-de-sac or fornix incision described by Marshall M. Parks, M.D. The unique aspect of this medial rectus recession is that it is carried out insofar as possible within Tenon's capsule, preserving, for the most part, the integrity of this structure. The theoretical advantage of recession of the medial rectus in Tenon's capsule is that it most nearly preserves the anatomy and presumably the normal physiology of the extraocular muscle by limiting the extent of postoperative adhesions. This has the added advantage of making reoperations easier. During the course of medial rectus recession utilizing this technique, bleeding is rarely encountered. In practice, in more than one-half of these procedures not a single cotton tip applicator is required to dry the field and only rarely is cautery required. External appearance at the conclusion of the procedure is routinely benign especially early in the postoperative period because of the location of the conjunctival incision behind the lower lid, an innovation of the aforementioned cul-de-sac procedure. Any redness appears under intact conjunctiva. My technique for measuring medial rectus recession employs the limbus as a reference point. This reference point was chosen because it offers a consistent landmark in contrast to the highly variable medial rectus insertion and allows the surgeon to know where on the globe the new attachment is placed as well as how far the muscle has been moved, especially if the medial rectus insertion site is noted. Following is a detailed, step-by-step description of medial rectus recession in Tenon's capsule. A newly designed set of strabismus surgical instruments is used and is illustrated. These instruments are for the most part modifications of instruments that have been employed for a hundred years or more. Principal among these are more delicate and some newly configured hooks which are better able to serve the surgeon working on smaller eyes and in tighter spaces. The new generation of retractors dubbed "Barbie," "Big Barbie," and "Great Big Barbie" replace ill-suited retractors that have been used by strabismus surgeons for many years; instruments that were made for general purpose and not specifically for strabismus surgery. Key to this technique is the Moody curved locking Castroviejo forcep, which acts as a self-retaining retractor and eliminates the need for traction sutures. Medial rectus recession in Tenon's capsule is designed to be carried out in a step-by-step manner with no extra moves and with minimal disruption of the anatomy. A combination of careful tissue handling and consistency of technique is the most reliable way to ensure satisfactory, consistent results. Eugene M. Helveston, M.D. Indianapolis, Indiana March 23, 2000

Recession of the Medial Rectus in Posterior Tenon's Capsule This procedure is modified from the cul-de-sac or fornix approach to the extraocular muscles. The procedure utilizes the following instruments: Finer, knobbed muscle hooks with a foot-shaft length of 12 mm, 10 mm, and 8 mm A "delicate" short foot-shaft length right angle "teaser" hook Thin, curved spatulated "Barbie" retractors Curved Moody-Castroviejo locking forceps Delicate locking forceps Delicate tying forceps Delicate tissue forceps of the surgeon's choice; Thorpe .5 mm (2-3 teeth), .12 mm (2-3 teeth), Lester (1-2 teeth), etc. Blunt tip Wescott spring-action scissors Lieberman blepharostat solid blade (small or large blades) Curved caliper Balanced salt irrigation Wet field cautery Cotton tip applicators 6-0 synthetic absorbable* suture -- .202 mm wire diameter needle -- spatula design; surgeon's choice (Check needle tip characteristics for "dig-in", neutral, "dig-out"!) Drape; surgeon's choice "Sterile preparation" -- face wash; surgeon's choice *Our choice is coated Vicryl.

Medial Rectus Recession in Posterior Tenon's Capsule Accomplishes the Following: Repositions the medial rectus muscle in the most physiologic way, with minimum disruption of surrounding fascial planes. Employs simple, repeatable steps which are done in an orderly fashion resulting in minimal manipulation of the tissue around the medial rectus. Minimal postoperative scar. Easier operation. Provides a nearly bloodless field during surgery (about 60% of these procedures require no blotting or cautery). In selected cases, "preventive" cautery can be applied to large, engorged anterior ciliary vessels. Conjunctiva may be closed with a single 8-0 synthetic absorbable* suture or simply reposited in the cul-de-sac without suture. Avoids the need to carry out the time consuming closure of the limbal incision. Contra-indications for the cul-de-sac procedure include Older patients with thin, fragile conjunctiva should not routinely have a cul-de-sac incision because this incision usually tears/extends and is difficult to close, leading to conjunctival scarring. For many of these same reasons, the limbal incision is easier to close in an adult compared to a child. In cases where conjunctival recession is indicated, a limbal incision is required. As with any new procedure, medial rectus recession in posterior Tenon's capsule has a "learning curve." The procedure  is no more difficult to perform than other types of medial rectus recession if the steps are carried out faithfully. Placement of the needle in sclera at the intended recession site is aided by steady retraction with the Barbie retractor. Exposure is less extensive than with the limbal approach, but there need to be no sacrifice in accuracy or in security of muscle placement. * Our choice is Vicryl.   Congenital Esotropia: 35 Diopters ET Early Post-Surgical Result: Orthotropia

_____________________________________________ Step #1 After carrying out forced ductions, a line is imagined connecting the 6 o'clock limbus and the base of the plica. The site of the initial conjunctival incision is 2/3 of the distance between these points, closer to the plica. The faint outline of the medial rectus, especially the lower border, can usually be seen through intact conjunctiva. Be sure to avoid making the incision too low, encroaching the fornix and entering into the orbital fat or too far medially cutting the plica! *Note: The  incision site is behind the insertion of posterior capsule at the spiral of Tillaux allowing access to free space under posterior Tenon's capsule. Surgery is shown on the right eye. Medial rectus of a patient oriented head up.

_____________________________________________ Step #2 The conjunctiva at the 4 o'clock limbus is grasped with a Moody-Castroviejo locking forcep and the eye is elevated and abducted exposing the incision site at the center of the operative field. The conjunctiva is grasped at a point 2/3 of the way between 6 o'clock limbus and the base of the plica with a fine tooth forceps. Wescott scissors cut a "button hole" in conjunctiva. The scissors tips are not pressed into sclera and no attempt is made to penetrate all layers down to sclera, in the first snip of the scissors.

_____________________________________________ Step #6 When the tip of the 10 mm muscle hook is on bare sclera, it is directed posteriorly at an angle of about 45º. When frees passage of the hook is assured behind the medial rectus insertion, the Moody-Castroviejo forcep is removed. Step #7 The muscle hook is directed fully across the medial rectus insertion until the knobbed tip is visible beyond the upper border of the muscle covered by posterior and anterior Tenon's and conjunctiva. This movement of the hook should proceed smoothly with no tissue resistance.

_____________________________________________ Step # 8 While the 10 mm hook firmly engages the medial rectus, the "teaser" hook is placed under anterior Tenon's capsule. This hook is then worked back and forth over the muscle hook at the muscle's insertion and toward the limbus to free these overlying tissues from those beneath in order to allow the incision made well below the muscle border to be brought upward, over the tip of the muscle hook thereby allowing exposure of the muscle's insertion but at the same time avoiding tearing the conjunctiva. This procedure requires patience and some firmness. It gets easier with practice.

_____________________________________________ Step # 9 The "teaser" hook slides the relaxed tissue over the tip of the 10 mm hook. When doing this maneuver, be sure to hold the 10 mm hook securely to keep the muscle fully engaged. This ensures that the tip of the muscle hook is covered only by posterior Tenon's capsule-intermuscular membrane. Step # 10 Wescott scissors cut a "button-hole" at the tip of the 10 mm muscle hook exposing a tiny opening to bare sclera at the muscle's upper border. This may take 2 or 3 "snips." Avoid cutting the muscle border -- be sure you look before cutting.

_____________________________________________ Step #12 A 6-0 synthetic absorbable suture is placed across the muscle just behind the 10 mm muscle hook. The needle is usually placed in two passes, first half way across -- retrieved then placed across the remainder of the muscle. Care should be exercised to avoid cutting the anterior ciliary vessels. A second, locking bite, is made at the upper and lower border, this time encircling the anterior ciliary vessels. The suture should be pulled firmly to set "true" knots at the muscle's border.

_____________________________________________ Step #13 A Wescott scissors cuts 1/3 of the muscle's insertion. A Moody-Castroviejo curved locking forcep grasps the corner of the stump of the insertion. *Note: Before starting to cut the muscle free, it is a good idea to cauterize large ciliary vessels if they are seen. This is not often necessary; but, when annoying bleeding occurs during this procedure, this is most often the source.

_____________________________________________ Step #14 Disinsertion of the muscle is completed and a second Moody-Castroviejo curved locking forcep is placed at the other corner of the insertion. These forceps keep the eye abducted and then maintain the incision centered over the insertion. The muscle now retracts freely, or at least as far as the attachments to intermuscular membrane allow.

_____________________________________________ Step #15 A caliper is used to determine the site of muscle reattachment. This measurement may be from the original insertion or from the limbus (as shown) according to the surgeon's preference. A curved ruler with a marking tip is particularly useful with the fornix incision. It is important for the surgeon to be consistent and to know where the muscle has been placed on the globe. The needle bite should be at least .2 mm deep and 1.5 mm in length to provide adequate muscle-scleral union during healing. *Note: Sclera is as thin as .3 mm immediately behind the medial rectus insertion in some cases. Sclera is a little thicker at the site of muscle reattachment in most cases. A thin (.202 mm wire diameter) needle with a sharp spatula tip is ideal -- there is great variation in surgeon's preference for scleral reattachment. Be consistent. After a second needle pass, the muscle is tied securely with a surgeon's knot.

_____________________________________________ Step #16 A single 8-0 synthetic absorbable* suture may be used to close the conjunctival incision. The aim of this surgery is to recess the medial rectus muscle and redirect the course of the spiral of Tillaux medially (backward) while retaining as much as possible anatomic integrity. *Our choice is Vicryl. At the conclusion of the procedure, the incision is hidden behind the lower lid. In the first few days postoperatively, the medial conjunctiva may be bulky and edematous. Occasionally, an extensive but totally harmless subconjunctival hemorrhage appears. Other than warning patients, nothing needs to be done about this. Recession of the caruncle is not seen with this procedure. Alignment results are similar to cases of medial rectus recession done with more extensive severing of the intermuscular membrane. Postoperative medication (drops) are according to surgeon's preference. A sulfa-steroid combination (or equivalent) twice a day for 5-7 days is adequate. No patches are used. Activity may be resumed as tolerated with no swimming for two weeks.