INTRODUCTION

SURGICAL INTERVENTION DURING ACTIVE

ORBITOPATHY

It is our practice to intervene in active disease only if there is significant exposure of the globe that will not respond to medical interventions, or if there is significant optic neuropathy. The three components of exposure that might require surgical intervention are severe proptosis, lid retraction (both upper and lower), and involvement of the inferior recti leading to a loss of normal Bell’s phenomenon. The graded surgical approach would suggest first trying to do simple lid surgeries to cover the cornea, starting with a temporal tarsorrhaphy and moving to upper and lower lid relaxing procedures (4,5). If, however, the orbit appears extremely tense and very chemotic, it might be appropriate to proceed to decompression with or without lid procedures in order to relieve both the proptosis and the congestive element associated with the crowded orbit. There are some circumstances when it is appropriate to release the inferior rectus, for example, when the eye is not only displaced downward by mass effect but hypotropic due to significant inferior rectus involvement.

There are three instances during the active phase of Graves’ orbitopathy when early decompression is appropriate for the management of optic neuropathy. All relate to physical and imaging evidence of effect on the optic nerve, either compression or stretching. With regard to apical compression, there are two sets of circumstances, one related to significant mass effect at the apex with secondary congestive features and the other is the anatomically small tight orbit syndrome. In both, the patients are suffering from the crowded orbital apex syndrome and we would normally intervene first with pulsed corticosteroids, to see whether the orbitopathy could be modified enough to improve the optic neuropathy, and delay surgery (until the orbit has ‘‘quieted’’ down). Usually this can be assessed within 1 week to 10 days of high-dose corticosteroids. Failing that, patients having significant proptosis with imaging evidence of enlarged muscles, dilated superior ophthalmic vein, dilated proximal end of the optic

nerve sheath, and profound proptosis may require decompression (6). Our choice of decompression method would be governed by the amount of decompression we wish to achieve (roughly 2 mm per wall) and the location of the disease within the orbit. Generally, these cases show quite profound relief of the clinical congestive features immediately after surgery; however, their outcome with regard to secondary strabismus is worse than the group that is either stable (nonactive) or are having decompression for cosmetic or reconstructive reasons (7). This correlates with both severity and activity of disease at the time of decompression.

The second instance in which decompression for optic neuropathy might be a primary choice is in the case of the small, tight orbit syndrome. This is usually seen in Asians or individuals who have evidence of relatively large marrow space at the junction of the lateral orbital wall and sphenoid wing, producing an anatomically tight apex (8,9). These patients respond dramatically to decompression, particularly if it takes advantage of expanding the greater wing of sphenoid in the posterolateral orbit as well as the medial orbit.

The final instance when surgery is appropriate for managing optic neuropathy is in the presence of significant proptosis with stretching of the optic nerve, which may cause globe tenting and optic neuropathy. This is an uncommon occurrence but would require active, early surgical intervention.

In the case of optic neuropathy, the key issue is to decompress the orbital apex and we tailor our procedure to focus on this as an outcome based on the preoperative anatomy. In addition, we consider other factors, such as the degree of desired reduction of exophthalmos or volume change (10,11).

STABLE ORBITOPATHY

The majority of patients with Graves’ orbitopathy who undergo surgery do so after the disease has been stable and nonprogressive for at least 6 months. It is the accepted paradigm that if a patient is to undergo surgery for thyroid orbitopathy that the order of management should be decompression

followed by muscle surgery followed by lid surgery, since decompression can affect motility and muscle surgery can affect the position of the lid (5). The general principles in managing these patients consist of a careful evaluation and individualization of approach, medical control to abate activity, patient education with regard to the risks and benefits of surgery, and the repair of mechanical and physical dysfunction in an orderly manner.

The decision making for the specific patient needs to take into consideration epidemiologic factors, such as age. The elderly usually require or prefer minimal intervention but are prone to more severe orbitopathy. Gender is also a factor in determining what the preferred outcome might be, which should be discussed and reviewed along with predisease photographs. Another epidemiologic factor is race, since in darker skinned people one would like to avoid or minimize skin incisions because of the potential for either pigmentation or depigmentation of the incision along with the possibility for hypertropic scarring. We have also noted that in patients with relatively tight lids, such as Asians, there is a tendency to lower lid epiblepharon and upper lid entropion brought about by the disease process, both of which need to be addressed by the surgical procedure.

Individual historical factors related to current and past surgical interventions as well as medical problems should be assessed prior to surgery. A review of the patient’s past physical appearance is useful in guiding desired outcomes. There are, of course, a number of individual physical factors, such as specific facial contour, status of the sinuses, globe size, refractive error, contour and status of the lids, and condition of the cornea and tear film, which should be taken into consideration when designing the appropriate surgical procedure. For instance, patients who have evidence of midfacial hypoplasia may require augmentation or advancement of the orbital rim in order to achieve a reasonable outcome. The sinuses should be evaluated preoperatively in order to determine whether or not preexisting disease is present and to evaluate the contour, particularly of the ethmoid sinus roof and the thickness of the bony structures. Globe size may

determine how much decompression can be logically achieved. As previously mentioned, lid contour and status need to be considered, particularly if there is evidence of in-turning of the lashes or significant scleral exposure. In some instances, patients with significant lower lid retraction who undergo decompression for their orbitopathy via a swinging eyelid approach can have lower lid lengthening procedures done at the same time. The need for lid position management may also relate to the state of the cornea and tear film.

There are a number of other disease-related factors that one should consider in surgical management of Graves’ orbitopathy. These include the degree and nature of muscle involvement, degree of proptosis, amount of orbital compliance, presence or absence of apical crowding, imaging findings, disease severity, and disease activity. With regard to the degree and nature of muscle involvement, I have already noted that an absence of Bell’s phenomenon associated with exposure may require muscle surgery at the time of decompression (inferior rectus recession). Sometimes, the surgeon may choose to avoid decompressing into the adjacent sinus if there is asymmetric and significant muscle involvement at that site. Degree of proptosis can affect the number of walls decompressed, which generally correlates with outcome insofar as one can achieve approximately 2 mm per wall decompressed and 0.7 mm for 1 cm3 of fat resection. There is also a need to evaluate the degree of orbital compliance, especially as it relates to the orbital apex (governed by the bony configuration) and to the orbital septum (governed by the lid position and tension).

Imaging plays an important role in assessing diseaserelated factors with regard to defining old vs. new disease, amount of orbital fat, configuration of the orbital apex and sinuses, and ruling out sinus disease. Imaging also allows for evaluation of the depth of the orbit as well as its bony structure. New or active thyroid orbitopathy on imaging is characterized by relatively diffuse muscle swelling with a minor degree of heterogeneity, whereas old disease is characterized by fat replacement of the muscle (2). It also appears