Surgical pearls address challenges of strabismus surgery

May 1, 2013

Avoiding hypotropia, excyclotropia after augmented transposition surgery among tips

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Jonathan M. Holmes, MD, discusses practical solutions for addressing selected problems encountered by strabismus surgeons.

 

By Cheryl Guttman Krader; Reviewed by Jonathan M. Holmes, MD

Rochester, MN-Maintaining a high index of suspicion for tight superior oblique involvement in patients with strabismus due to thyroid eye disease, and then monitoring intraoperative torsion to detect its presence, can help strabismus surgeons avoid postoperative A-pattern exotropia and incyclotropia, according to Jonathan M. Holmes, MD.

This was one of the practical solutions offered by Dr. Holmes. In addition, he discussed avoiding hypotropia and excyclotropia after augmented transposition surgery and a posterior fixation suture modification incorporating adjustable recession for addressing incomitant deviations.

Tips for strabismus surgery

“Surgeons who operate on enough patients with thyroid eye disease may have encountered postoperative A-pattern exotropia and incyclotropia, and one mechanism may be a mechanical effect from over-recession of the inferior rectus muscles,” said Dr. Holmes, Joseph E and Rose Marie Green Professor of Visual Sciences, Mayo Clinic, Rochester, MN. “However, I would propose that, in some cases, this problem is due to the involvement of the superior oblique muscle by the thyroid eye disease that is masked by coexistent inferior rectus muscle involvement.”

To identify involvement of a tight superior oblique muscle intraoperatively, Dr. Holmes recommended assessing the torsional position of the eye before and after disinserting the inferior rectus muscle and performing an exaggerated traction test of the superior oblique muscle after disinserting the inferior rectus muscle. To help with the assessment of the torsional position of the eye, he suggested placing dots on the limbus at the 6 and 12 o’clock positions using a surgical skin marking pen. If tightness of the superior oblique muscle is detected, the superior oblique tendon should be recessed to weaken it.

Preoperatively, the presence of superior oblique involvement by the thyroid eye disease may be suspected clinically by measuring cyclotropia using double Maddox rods or the synoptophore, Dr. Holmes said.

“In the context of a tight inferior rectus muscle, if there is only a small amount of excyclotropia, between 0° and 5° (less than expected with a very tight inferior rectus muscle), or frank incyclotropia, surgeons should suspect coexistent superior oblique muscle involvement,” he explained. 

Further details are published in Holmes JM et al.  J AAPOS 2012;16:280-285.

Avoiding vertical deviation

Monitoring torsion intraoperatively may also help surgeons avoid hypotropia and excyclotropia after augmented transposition surgery, for example, with Foster sutures. Again, Dr. Holmes recommended monitoring the torsional position of the eye intraoperatively using preplaced limbal markings with a skin marking pen.  Showing that incyclotropia occurs after initial tightening of the superior rectus Foster suture, he said that surgeons can monitor the torsion while tying the inferior rectus Foster suture.

“I use a bow tie for the inferior rectus Foster suture, starting by tying the suture with the inferior rectus muscle belly 2 mm from the lateral rectus and then I check the torsional position of the eye, adjusting the tension of the Foster suture and the position of the inferior rectus muscle belly, until the torsional position is neutral, to protect against the hypotropia, which tends to be associated with the excyclotropia,” Dr. Holmes explained.

Further details are published in: Holmes JM et al. J AAPOS 2012;16:136-140.

Posterior fixation

The third technique he discussed was the use of a posterior fixation suture with adjustable recession to address the situation of a small deviation in primary gaze with a large deviation in eccentric gaze. Here, the surgeon disinserts the inferior rectus muscle (for example) from the sclera, places the posterior fixation suture 15 mm back from the insertion centrally, and passes the double-armed 6-0 Mersilene suture through the muscle at one-third of the muscle width from each of its edges.  The inferior rectus muscle is reattached with 6-0 Vicryl using a sliding noose adjustment, and the Mersilene suture is then tied over the belly of the muscle, opposed to sclera, but not so tight to preclude adjustment of the recession.

 “With this technique, surgeons can still use an adjustable hangback recession to titrate the alignment in straight ahead gaze, while still having the advantage of posterior fixation to address the incomitance,” Dr. Holmes said.

Further details are published in Holmes JM et al. J AAPOS 2010;14:132-136.

 

Jonathan M. Holmes, MD

E: holmes.jonathan@mayo.edu

Dr. Holmes has no financial interest in the subject matter. This article is adapted from Dr. Holmes’ presentation during Pediatric Ophthalmology 2012 at the annual meeting of the American Academy of Ophthalmology.