Strabismus Surgery in Thyroid Eye Disease

Physicians at Cleveland Clinic’s Cole Eye Institute have recently published 10-year outcome data on a technique for improving the outcomes of strabismus surgery in patients with Graves disease. Developed by Elias Traboulsi, MD, Head of the Department of Pediatric Ophthalmology at Cleveland Clinic, the surgery is intended for the approximately 5 percent of patients with thyroid eye disease whose illness necessitates strabismus surgery.

One of the complications of Graves disease is the development of an orbital inflammatory process involving the extraocular muscles that move the eye, particularly the inferior rectus and medial rectus muscles. As the muscles become inflamed and larger in volume, patients develop proptosis. Additionally, inflamed and stiff muscles lead to restrictive strabismus, diplopia and compression damage to the optic nerve. Decompression surgery, wherein bones of the floor of the orbit’s medial wall are surgically broken, provides more volume for the eye to fall back and relieves pressure on the optic nerve. However, this surgery can consequently cause diplopia and strabismus if muscles are trapped or displaced in newly created openings.

The case for a new technique

The inflammation-induced fibrosis and thickened extraocular muscles limit the predictability of strabismus surgery. “This makes for a real challenge for the surgeon,” says Dr. Traboulsi. “It is hard to predict how far you will need to move the insertions of those extraocular muscles. The tables that inform the surgeon how many millimeters to adjust the muscles back according to the level of prism diopter deviation — which were developed for use on a pediatric population — do not work because the muscles are abnormal.”

To improve the surgical outcomes, Dr. Traboulsi and colleagues developed an intraoperative relaxed muscle positioning technique that improves ocular alignment and relieves diplopia in the majority of surgical patients.

In contrast to traditional adjustable strabismus surgery, where muscle position changes are made when the patient is awake, this technique is performed while the patient is under general anesthesia. “In the traditional adjustable suture technique, with the patient awake, we ask them to look straight ahead; we adjust the position of the muscle insertion so that they are not seeing double, and then we tie the suture at that time,” explains Dr. Traboulsi. With the revised technique, the eye is placed straight forward with the patient asleep and the muscle tendon is reinserted where it naturally lies. With traditional techniques, the muscle is attached to an adjustable suture that can and does move over time, allowing for postoperative manipulation, and reoperation rates vary from 8 to 27 percent. In the revised technique the muscle is attached directly to the sclera where it is more secure, preventing muscle slippage.

Positive surgical outcomes

In the 10 years of experience on approximately 60 patients at Cleveland Clinic, physicians reported that the final outcome after one surgery was good or excellent in 52 patients (90 percent). “Our outcomes also show that exact measurements of how much the eye has drifted one way or the other are not as important as previously thought,” adds Dr. Traboulsi.

Along with achieving very positive outcomes, this approach removes much of the surgical estimation where to suture the muscle. “I have been told many times that surgeons are relieved to have a method that is simple and predictable and that provides such good results,” says Dr. Traboulsi. “It takes away a lot of the anxiety about what to do for their patients.”