The surgery can be performed in under an hour and is usually an outpatient procedure. Each of the four rectus muscles are identified, disinserted from the globe, and tagged with a suture. The inferior oblique muscle and superior oblique tendon are identified and transected. The optic nerve is then transected, and the eye is removed.
For a patient with a tumor, in particular retinoblastoma, it is important to obtain as long of a piece of optic nerve as possible (Figure 2).
An orbital implant is placed in the socket, and the rectus muscles are attached to the implant. The Tenons layer and conjunctiva are closed separately to finish the surgery. A conformer is placed to retain the fornices, and a pressure patch is placed for at least two days. The patient will follow up in one week for reevaluation.
The placement of an orbital implant is performed for two reasons. First, the implant provides volume to the orbit. If an implant was not placed, a large, bulky prosthesis (artificial eye) would be needed, which is not ideal. The second reason to place an implant is it can improve movement of the prosthesis and maintain the anatomy of the orbit. Although there is controversy regarding how a prosthesis moves, many believe that the movement of the orbital implant improves movement of the prosthesis. By attaching the rectus muscles to the implant, better movement is obtained.
Implants can be made from porous or solid material. Porous material has the advantage of having the patient’s tissue grow into the pores; the implant then becomes “part” of the patient and will not migrate.
Implants come in different shapes. Most commonly, a spherical implant is used, but some implants have mounds on the front that may aid in the movement of the prosthesis.
The prosthesis is made by an ocularist four to six weeks after the surgery. In general, the patient should see the ocularist once a year for prosthesis polishing and checking the fit. The patient will have better success if he does not manipulate the prosthesis himself. The prosthesis rarely needs to be removed except for examination once a year by the oculoplastic surgeon and ocularist.
The most common complications after enucleation are implant related.
Implants can become exposed for several reasons: dehiscence of the surgical wound, poorly vascularized conjunctiva, infection of the implant, and mechanical pressure from the prosthesis.2
If an implant is exposed, it should be repaired. Techniques for repair depend on the size of the exposure. With time, the patient can lose volume in the orbit, likely due to fat atrophy. The prosthesis may need to be enlargeda large prosthesis does not fit and move as well as a thinner prosthesis. Due to the potential problems with volume after the surgery, the largest implant possible is placed at the time of the surgery.
An enucleation in a children is a special situation. Volume is very important in children to help the orbital bones grow. Sometimes it is useful to implant a dermis-fat graft, which is tissue from the patient that will grow with the patient and help maintain volume and adequate bone growth.3