Endoscopic Dacryocystorhinostomy

Before the endoscopic age, attempts to surgically treat orbital disease through a transnasal approach were often fraught with poor visualization and poor outcome. The best documented attempt to perform a dacryocystorhinostomy (DCR) through the nose was described in 1921 by Harris P. Mosher, who then served as chairman of the Department of Otology and Laryngology at Harvard Medical School. Using a headlight and nasal speculum, he described the drainage of pus from the infected lacrimal sacs of 12 patients. Although this intranasal approach avoided the need for a facial incision, a postoperative orbital infection developed in one patient who almost lost her eye, prompting Mosher to abandon the procedure in favor of a combined external-intranasal approach. In his words, “Where light is possible it is folly to work in the dark. The best surgery is done by sight.” For the next 70 years, DCRs were performed almost exclusively in an external manner through a medial canthal incision, and largely by ophthalmologists.

With the advent of small-diameter, high-resolution nasal endoscopes for sinus surgery in the mid-1980s, a renewed interest developed in the possibility of accessing orbital pathology through the nose. Otolaryngologists found themselves routinely operating in the vicinity of the lacrimal sac as they cleared disease from adjacent ethmoid air cells under excellent visualization. While doing so, the potential to readily access the medial orbital structures via a transnasal approach became readily apparent, and early reports in the literature supported the concept.

In 1989, I was approached by Daniel Townsend, an ophthalmologist at Massachusetts Eye and Ear Infirmary, who had recently performed an external DCR on a 52 year-old woman, only to have her troublesome tearing return 3 months later. When I examined the patient in the office with a nasal endoscope, a dense scar band could be seen overlying the region of the lacrimal sac along the lateral nasal wall. She appeared to be an ideal candidate to revisit Mosher’s intranasal DCR approach, this time with the necessary “light” and visualization to perform a safe and effective surgery.

The trip to the operating room proved to be a fruitful one. The ophthalmologist passed lacrimal probes through the canaliculi to localize the obstructed lacrimal sac while I resected the scar tissue and made a wide opening around the probes into the sac. The patient tolerated the 90-minute procedure well, and her epiphora has not returned in more than 30 years.

The early success of endoscopic DCR led to its relatively rapid adoption by other surgeons at our hospital and across the country. The benefits of avoiding a facial incision and reducing patient morbidity offered by endoscopic DCR were obvious. However, not so obvious at the time were the subtleties of patient selection and surgical technique that affected clinical outcome.

One such example was the use of surgical lasers, which were quite popular at the time, for the performance of endoscopic DCR. Although laser fibers could be passed through either the tear duct or nose to remove bone overlying the lacrimal sac, their use led to postoperative scar formation and restenosis. Laser endoscopic DCR had a success rate of 78% compared with a rate of more than 90% for conventional DCR. Because of these early setbacks, endoscopic DCR lost favor among many ophthalmologists who continued to perform conventional external DCR. Nevertheless, with increasing clinical experience, the performance of endoscopic DCR was refined and its adoption grew worldwide. Numerous reports over the past decade have described the safety and efficacy of this technique with results comparable to those of external DCR.

Endoscopic Orbital Decompression

Not long after the successful introduction of endoscopic DCR, sinus surgeons began to consider other possibilities for transnasal treatment of orbital pathology. At the completion of routine ethmoidectomy for chronic rhinosinusitis, the skeletonized lamina papyracea was in full view, yet its penetration was assiduously avoided for fear of exposing orbital fat and causing injury to intraorbital structures.

Those of us who trained in otolaryngology before the endoscopic era were familiar with the Walsh-Ogura transantral approach for treatment of patients with exophthalmos from Graves’ disease. Surgery started with a transoral incision to open the maxillary and ethmoid sinuses. The bony orbital floor and lamina papyracea were then removed, resulting in orbital decompression with immediate reduction in proptosis. But could similar surgery be performed through an endoscope? The answer came in 1990 when David Kennedy and his ophthalmologic colleague, Neil Miller, at Johns Hopkins described the successful treatment of eight patients with Graves’ orbitopathy using an endoscopic technique. Two of the patients underwent simultaneous Walsh-Ogura procedures to verify that adequate bone had been removed endoscopically along the orbital floor.

Later that year, I was approached by John Shore, an innovative ophthalmologist at Massachusetts Eye and Ear, who had a 38-year-old patient with a severe case of Graves’ orbitopathy. He was particularly concerned about impending vision loss in this individual who had already had a vision-threatening corneal abrasion and was in need of a thorough decompression, including the region of the orbital apex, which can be difficult to visualize through a conventional approach.

When we took this first patient to the operating room, the ophthalmologist was amazed at the excellent visualization in the region of the orbital apex afforded by the endoscope. After removal of the entire lamina papyracea, I incised the periorbita in a posterior-to-anterior direction, resulting in immediate prolapse of orbital fat and reduction in the patient’s proptosis. A tense orbit was now soft, and the referring physician was now sold on the advantages of an endoscopic approach to the medial orbit. A week after surgery, the patient’s exophthalmos was 8 mm less than its preoperative level, but he did not have the postoperative facial swelling, numbness, and ecchymosis associated with nonendoscopic approaches to the orbit. The enhanced visualization and reduced patient morbidity afforded by the approach to the medial orbit led to a rapid growth in the number of endoscopic decompressions performed nationwide during the 1990s.

Within the first 5 years of performing orbital decompressions, however, an unanticipated problem became evident: development of new-onset diplopia that was difficult for the strabismus surgeons to correct. We had known for many years that double vision was an expected sequela to orbital decompression in many patients, but the severity and incidence of the diplopia was troubling. An analysis of our results suggested that the problem was due to the thoroughness of medial orbital decompression when performed with endoscopic instrumentation compared with conventional transantral or transorbital approaches. Removal of the entire lamina papyracea and periorbita resulted in a greater prolapse of orbital fat and herniation of the medial rectus muscle into the sinonasal cavities than occurred with conventional approaches. This finding was particularly apparent in patients who had undergone only medial decompression without a concurrent lateral decompression.

Similar findings were reported by other authors who recommended the use of a “balanced decompression” technique with concurrent medial and lateral decompressions at the same operative setting. This balanced decompression resulted in a significantly lower incidence of postoperative diplopia. It made sense that the lateral decompression relieved inward pressure on the orbital contents, resulting in less medial displacement of the orbital contents, including the medial rectus muscle, and thereby caused less double vision. Balanced decompressions are now performed on the majority of patients with Graves’ disease in my practice who require surgical decompression. Only those with relatively mild proptosis and no optic neuropathy undergo medial decompression alone.

Another procedure developed to reduce the incidence of postoperative diplopia in patients with Graves’ orbitopathy is known as the “orbital sling” technique. A 10-mm wide strip of the periorbita overlying the medial rectus muscle is preserved to prevent medial displacement of the muscle during surgery. Orbital fat is free to herniate above and below the fascial sling, providing adequate decompression of the orbital contents. When a balanced technique is used in the majority of patients, supplemented by the use of an orbital sling in select patients, the results of endoscopic orbital decompression are comparable to those of transantral and transorbital techniques, including the degree of decompression achieved and relatively low incidence of postoperative complications.

Unlike endoscopic DCR, ophthalmologists gravitated relatively quickly to the concept of endoscopic orbital decompression. They realized the obvious advantages of endoscopic instrumentation for such surgery, including better visualization along the skull base and a more complete removal of the lamina papyracea than could be achieved with conventional approaches. The majority of orbital decompressions performed today use a team approach. It is common for the ororhinolaryngologist to perform the medial portion of the decompression while the ophthalmologist follows with the lateral decompression.

Endoscopic Optic Nerve Decompression

Endoscopic optic nerve decompression is a natural extension of orbital decompression. Bone removal along the posterior orbit is continued into the sphenoid sinus following the optic canal as it courses along the lateral sphenoid wall. In the 1990s, a relatively large number of optic nerve decompressions were performed on patients who lost vision after head trauma, particularly during motor vehicle accidents. There was much debate at the time as to the best surgical approach to use to decompress the optic nerve in patients who lost vision after head trauma—endoscopic, open, transorbital, or transcranial. The debate ended when high-dose steroids were found to be just as effective as surgical decompression of the optic canal in these patients.

Most individuals who present with optic neuropathy as a component of Graves’ orbitopathy do very well after endoscopic orbital decompression alone. Provided adequate bone is removed to decompress the region of the orbital apex, their neuropathy, including the associated color blindness and visual field loss, usually resolves. Some ophthalmologists, however, do favor decompression of the optic canal at time of endoscopic orbital decompression in patients with severe optic neuropathy.

Endoscopic optic nerve decompression remains an excellent procedure in those patients whose visual loss is due to compression of the optic nerve within the sphenoid sinus from neoplasms, such as meningiomas, or osseous lesions, such as fibrous dysplasia. Experience has shown that unroofing the bony canal in the affected area is sufficient to restore vision in most cases. Incision of the optic nerve sheath is not necessary.

Endoscopic Resection of Orbital Tumors

The inferior and medial rectus muscles are routinely exposed during endoscopic orbital decompression. Manipulation of these muscles to gain access to the intraconal region of the orbit was a natural extension of this surgical approach. Successful endoscopic removal of tumors of the medial orbit has been described by a number of authors. Most of the early experience was with resection of orbital hemangiomas, which are not only the most common intraorbital tumor encountered but also are well encapsulated, facilitating their dissection from surrounding orbital contents. As experience with these techniques has advanced, the size, location, and pathology of orbital tumors successfully resected through an endoscopic approach have also advanced.

Future Directions

The history of endoscopic orbital surgery over the past 30 years reflects a natural progression of surgical exploration: from superficial to deep, from medial to lateral. As both the techniques and technologies associated with endoscopic orbital surgery advance, so too will the indications, extent, and success of these procedures. I foresee the day when otolaryngologists will work with ophthalmologists to perform surgery on extraocular muscles—retrieval of lost muscles during strabismus surgery, and remodeling of diseased muscles from Graves’ disease. Endoscopic instrumentation also has potential benefits in the field of neuroophthalmology—placement of retinal and optic nerve implants, fenestration of the optic nerve for treatment of patients with visual loss from intracranial hypertension, and decompression of the optic nerve in patients with ischemic neuropathy.

Conclusion

The fields of otolaryngology and ophthalmology were once a single specialty. The advent of endoscopic techniques to treat patients with orbital disorders has served to foster the collaborative efforts of surgeons in these two specialties once again. With the growing use of endoscopic instrumentation to treat orbital disease, the future of endoscopic orbital surgery is a bright one, enabling surgeons and their patients to truly “see the light.”