Basic concepts of suturing require good technique, art

Placing sutures correctly is an integral part of ophthalmic surgical technique.

Issue: February 15, 2007

ByUday Devgan, MD

The development of small-gauge ophthalmic sutures revolutionized the field of cataract surgery decades ago. With the move to self-sealing incisions, our use of sutures for routine cataract surgery has become less common, but it is still important for other ophthalmic surgeries. These tiny sutures, typically 10-0 in size, can be challenging to use given their low tensile strength and the small circular needles.

While ophthalmologists in practice are already experts in using 10-0 nylon to suture incisions or corneal wounds, it helps to review some of the basic concepts to further hone our techniques. For our ophthalmology residents, learning these basic concepts of suturing is an important part of the foundation of ophthalmic surgical technique.

Uday Devgan

How to suture

The sutures typically come with semi-circular needles that create circular paths when they are passed through tissue. There should be no linear pushing with these needles; otherwise they will bend and distort the tissues. Rather, the movement used to pass these sutures is similar to turning a screwdriver in a circular motion (Figure 1). Sutures should be placed symmetrically so that an even amount of tissue on either side of the incision is captured by the suture. This results in optimum holding power of the incision, better long-term stability and a lower likelihood of cheese wiring through the tissues (Figure 2).

The entry angle of the suture plays a large role in determining the depth of the suture. Because the needle creates a circular path, acute angles of less than 90° result in shallow passes, while obtuse angles of more than 90° result in deeper passes. If the needle entry angle is 90°, then the circular path of the needle will result in a depth equal to the radius of curvature of the needle (Figure 3).

Figure 1: Passing a suture with a semi-circular needle
To pass a suture with a semi-circular needle, the movement is like turning a screwdriver in a circular motion. Excessive pushing in a linear manner will cause the needle to bend and the tissues to distort.

Figure 2: Symmetrical suture placement vs. asymmetrical closure
Symmetrical suture placement (B) results in optimal holding power and wound closure. Asymmetrical closure (A and C) does not provide the same security.

Figure 3: Entry angle of the needle will determine depth of suture placement
The entry angle of the needle will determine the depth of the suture placement. (A) Acute angles result in shallower sutures. (B) Right angles result in normal depth, equal to the radius of the needle. (C) Obtuse angles may result in excessively deep suture passes.

Figure 4: Holding power is strongest under the suture
The holding power is strongest under the suture, and it decreases as you move farther away, distributing the forces in a diamond shape.

Figure 5: Comparison of different suture lengths
(A) Short sutures distribute their force over a small area, therefore more sutures are required to close the incision. (B) The ideal balance of suture length and spacing, where the forces provide good holding power for the entire incision. (C) An overly long suture may distribute the forces over too large an area and therefore give less effective holding power for the incision.

Images: Devgan U

The suture holding power is greatest directly under the suture itself, and this diminishes as you move farther away. The resulting forces from the suture result in a diamond-like distribution pattern (Figure 4). Shorter sutures distribute their force over a smaller area, and therefore, more sutures are required to close the incision or wound. This may be helpful in situations in which higher strength closure of the wound is required. Sutures that are placed at a more ideal length will provide good holding power at the incision while minimizing the number of sutures required for a given length of incision. Overly long sutures tend to distribute the closure force over too broad an area, and as a result, they may give less effective holding power for the incision (Figure 5).

Placement

Suture placement in clear corneal incisions should be radial, much like the spokes of a bicycle wheel. The needle should be grasped at about one-third the distance from the swaged end to the point, and the needle-holder should be unlocked before passing the suture. When tying nylon monofilament sutures, it is customary to tie interrupted sutures with three knots in a 3-1-1 manner: The first knot should be three throws, and the second and third knots should be one throw. These three knots are placed in alternating directions in order to create square knots. Sutures placed in the cornea can then typically be rotated so that the knots are buried within the corneal stroma, which aids in patient comfort while helping to prevent unraveling of the knots.

Placing a suture with good depth, symmetry, spacing and length with the correct tensile forces is an art and an integral part of ophthalmic surgical technique.

For more information:

Uday Devgan, MD, FACS, is in private practice at Devgan Eye Surgery in Los Angeles, Beverly Hills, and Newport Beach, California. Dr. Devgan is Chief of Ophthalmology at Olive View UCLA Medical Center and an Associate Clinical Professor at the Jules Stein Eye Institute at the UCLA School of Medicine. Dr. Devgan can be reached at 11600 Wilshire Blvd., Suite 200, Los Angeles, CA 90025; 800-337-1969; fax: 310-388-3028; e-mail: devgan@gmail.com; Web site: www.DevganEye.com. Dr.Devgan is a consultant to Abbott Medical Optics and Bausch & Lomb, and is a stockholder in Alcon Laboratories and formerly in Advanced Medical Optics.

References:

Johnson & Johnson Ethicon Wound Closure Manual. Available at: www.jnjgateway.com/public/USENG/Ethicon_WCM_Feb2004.pdf. Accessed January 18, 2007.

Roy FH, Arzabe CW. Master Techniques in Ophthalmic Surgery. Thorofare, NJ: SLACK Incorporated; 2004.