and Yi Ning J. Strube2
(1)
Wright Foundation for Pediatric Ophthalmology and Adult Strabismus Medical Center, Los Angeles, CA, USA
(2)
Queen’s University, Kingston, Ontario, Canada
Keywords
Wright grooved hookTopical anesthesiaFixed suture techniqueHang-back techniquePain during strabismus surgeryTopical anesthesia strabismus surgery reduces the systemic risk associated with general anesthesia, as well as the postoperative nausea and vomiting. It also eliminates the risk of globe perforation, optic nerve damage, and myotoxicity that is associated with retrobulbar injection. Topical anesthesia can be especially useful in senior citizens who have medical issues that make general anesthesia dangerous.
The authors reserve topical anesthesia for cooperative adult patients and only for virgin rectus muscle recessions, including bilateral surgery and vertical or horizontal rectus muscle surgery. Others (who are perhaps braver and more skilled) have used topical anesthesia for resections. Topical anesthesia works well for rectus muscle recessions in patients with thyroid-related strabismus.
12.1 Principles for Avoiding Pain
Pain during strabismus surgery originates from two main sources: the conjunctiva and the extraocular muscles. Manipulation of the Tenon’s capsule and sclera does not result in pain. Grasping the scleral insertion with locking forceps and scleral needle passes can be performed safely without discomfort.
The conjunctiva can be anesthetized with topical anesthesia using tetracaine and lidocaine gel. We use multiple doses of both topical tetracaine and lidocaine gel prior to surgery. The extraocular muscles provide a more difficult hurdle, as we cannot anesthetize the muscles without a retrobulbar injection. Pain from the extraocular muscles does not arise from pain receptors, as cutting the muscle or passing a needle through the muscle is not painful. Muscle pain comes from stretch receptors and is elicited by pulling on the muscle. Even gentle pulling on a rectus muscle will cause significant pain—gut-wrenching, deep, visceral pain that must be avoided. Once the patient experiences pain from muscle pull, confidence will be lost, making the rest of the surgery miserable for both the surgeon and patient alike.
Standard strabismus surgery is based on pulling on the muscle to gain muscle exposure, so special techniques are required for topical anesthesia to minimize muscle pull. First, avoid the fornix approach, which requires significant pulling on the muscle. Use a limbal or Swan incision to gain wide and easy access to the muscle insertion. We prefer the limbal incision for the horizontal recti and the Swan incision for vertical recti. In addition, do not use a muscle hook to pull the muscle insertion into the surgical field. Instead, establish exposure of the muscle insertion by use of a limbal traction suture. Finally, do not pull up on the muscle to tent the muscle off the sclera for suturing. Rather, place a Wright grooved hook under the muscle to provide a space for suturing without pulling. The surgeon must avoid the temptation of pulling on the muscle—something we were all taught and do routinely in standard strabismus surgery.
Note
Some surgeons will use a hang-back technique and tie the muscle with a bow tie knot so the muscle can be adjusted. Topical anesthesia does allow for intraoperative adjustment and immediate assessment of alignment. Except for rare cases that are exceptionally complex, however, we prefer the fixed suture technique, as in the past the senior author (KWW) has often adjusted himself out of a good result. Laurie Christensen et al. from Portland, Oregon, substantiate this clinical impression, reporting excellent results in complex cases of thyroid-related strabismus using the fixed suture technique [1].
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