Adjustable or Tied-Off Sutures in Strabismus Surgery?

Same-Day Adjustments Bring Patients Closer to Intended Postoperative Range

Ron Zimmerman

April 06, 2012

April 6, 2012 (San Antonio, Texas) — Some strabismus surgeons operating for ocular misalignment leave their sutures long in order to be able to make postoperative adjustments. Other surgeons believe that patients achieve better results if their sutures are simply tied off in the original operation. In a study conducted by Jonathan Holmes, MD, and colleagues at the Mayo Clinic in Rochester, Minnesota, patients undergoing adjustable surgery had better outcomes overall than those undergoing tied-off surgery.

The study was presented here at the American Society of Pediatric Ophthalmology and Strabismus (AAPOS) 38th annual meeting.

Dr. Holmes' team compared the 2 methods — directly tying off sutures and adjusting the position of the muscle by using adjustable sutures — to see whether the process of adjustment resulted in worse outcomes over time.

Dr. Jonathan Holmes

They retrospectively analyzed the cases of 90 patients who underwent reoperation for horizontal strabismus. Of these, sutures for 54 patients (60%) were adjusted and those for 36 (40%) were simply tied off. Success at 6 weeks and 1 year after surgery was defined as an angle less than 10 prism diopters and lack of diplopia.

At 1 year after surgery, 78% of the adjusted patients were successful compared with 67% of those with tied-off sutures (P = 0.3).

Dr. Holmes speculated that without immediate postoperative adjustment, the outcome of the patients would have been worse because preadjustment angles were as large as 30 XT and 35 ET.

He concluded that there is no evidence that adjustment yields inferior results compared with tying off and that without adjustment, some patients would have had poor outcomes.

Why is this an important question? As Dr. Holmes explained, "Ultimately it would be best to have a randomized study of the 2 approaches (adjustable vs fixed sutures), but in the meantime, I thought there would be another way to look at the question. Occasionally I would have a patient where I had done adjustable sutures, moving the muscle later that evening and the patient did not end up with the result that we wanted. I wondered, had I just adjusted the patient out of a good result?"

"Anecdotally," Dr. Holmes recounted, "by having adjustable sutures, I was able to bale myself out of an alignment I didn't think was going to end up in a long-term good situation. And overall, we found that looking at the 1-year postoperative results, that the ones that we adjusted had at least as good as a result as the ones we tied off. That's what we hoped for, but the data speaks for itself."

For his study, Dr. Holmes divided his patients into 2 groups: those with eyes that cross (esotropic) and those that wander out (exotropic). Within those groups, he further divided them by ability to fuse their 2 eyes together and inability to do so. Among these 4 groups, esotropic/exotropic and nonfusing/fusing, Dr. Holmes says he was wondering whether he would find differences.

He looked closely at his data and noticed that the patients in the adjusted fusing/exotropic group had lower success rates at the 6-week milestone. He discovered they had more double vision but that it was a result of his intentional overcorrection.

"We had deliberately adjusted them to have some double vision," he explained. "The reason we do that is that there's good literature on patients with exotropia that they tend to drift back out their original misalignment. So we position those patients slightly esotropic, where the patient experiences some temporary double vision. What happened between 6 weeks and 1 year was that the groups became much more similar. The patients that we had adjusted initially had more severe diplopia, but, as we expected, they drifted back towards a straight alignment."

One of the take-home messages for strabismus surgeons doing adjustable sutures, according to Dr. Holmes, is that the 6-week outcomes don't tell the whole story. "Because we adjust patients into a target range, it is in some situations an overcorrection anticipating a postoperative drift. You have to warn patients," he says, "that they may have some unexpected — unless you explain it to them — double vision immediately after the surgery and that may take a number of weeks to resolve. And that's important in counseling the patients."

Dr. Holmes prefers to do the adjustment later the same day and not wait until the next morning, as he used to do. "If you adjust within 4 hours," he says, "then the muscle hasn't had a chance to stick to the eyeball and many patients experienced very little discomfort. We just use topical eye drops to perform the adjustment."

Strabismus surgeon Richard Saunders, MD, from Medical University of South Carolina Children's Hospital's Storm Eye Institute in Charleston, says he believes the decision to use adjustable versus fixed sutures relies on the experience of the surgeon. "I tend to not to use adjustable sutures in routine cases because adjustable sutures do have downsides. I don't think I would make a blanket statement that all adult patients undergoing reoperation should undergo adjustable sutures. Some surgeons are frankly much better at judging the amount of fixed surgery than others — much better — and that comes with a lot of experience. The nice thing about fixed surgery is that it's over. You don't have to manipulate the patient again. I think there's a little less morbidity."

Nevertheless, Dr. Saunders says that the Holmes study covers an important concept and that in some small percentage of his cases, he does use adjustable sutures.

"Adjustment can be done at a variety of times, I do it within 2 hours, but it can be done later in the week," Dr. Saunders says. "But if you're adjusting that much later, I think for truth-in-labeling here, at some point you have to call this a reoperation. Some people code it that way. Also, the question is when is the morbidity for the patient, the time and expense, no longer worth it, even when the results of adjustable sutures are a tad better, statistically? I don't know the answer to that."

In contrast, surgeon Patrick Watts, MD, from Cardiff, Wales, reports that he uses adjustable sutures in 95% of his adult reoperations for exotropia/esotropia.

"I tend to do all adults with adjustable sutures," Dr. Watts says, "except when they refuse to have it done. The method Dr. Holmes uses is exactly what I do. If I get within the target angle then I will tie them off, as opposed to not within the target angle and that's the whole point of the adjustment. It's reassuring to know that they don't do any worse. That's the whole premise of this study, that we're not adjusting ourselves out of a good result. I wait 4 hours; I feel the more awake my patients are, the more cooperation I get from them. Sleepy patients, groggy from their surgery, may alter the adjustment results."

Dr. Holmes underlines the value of his study. "The takeaway is, that even though we see an occasional patient where we wonder whether or not adjusting them has resulted in a less-than-optimum outcome, on average we do not adjust ourselves out of a good result and in fact, the philosophy of putting a patient into a desired immediate postoperative target range is the best course of action for a long-term good result."

Dr. Holmes, Dr. Saunders, and Dr. Watts have disclosed no relevant financial relationships.

American Society of Pediatric Ophthalmology and Strabismus (AAPOS) 38th Annual Meeting (AAPOS). Paper #5 Presented March 25, 2012.

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