Understanding the techniques of eye removal
Three techniques used for eye removal: evisceration, enucleation, and exenteration. Each procedure has specific indications, and each procedure has its advantages, disadvantages, and complications.
Three techniques used for eye removal: evisceration, enucleation, and exenteration. Each procedure has specific indications, and each procedure has its advantages, disadvantages, and complications.
The loss of an eye is not trivial and can be very traumatic for the patient; special care should be given to ensure that all preoperative and postoperative concerns are addressed.
Let’s review each procedure and discuss care of the anophthalmic socket.
Enucleation
Enucleation is the removal of the entire eye. Indications for enucleation include intraocular tumors (most commonly melanoma and retinoblastoma) which are unable to be controlled with other methods and blind eyes after trauma.
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The advantage of an enucleation is it gives a good specimen for the pathologist to determine evidence of spread beyond the eye. The disadvantages of enucleation are it is a longer surgery than evisceration, and the normal anatomy of the orbit is not retained, which predisposes the patient to postoperative complications.
Enucleations are considered after trauma in situations in which the eye is blind. In this case, enucleation is performed within two weeks of the trauma to prevent sympathetic ophthalmia.
Sympathetic ophthalmia is a rare condition in which the untraumatized eye becomes inflamed due to the exposure of the immune system to antigens from the traumatized eye, resulting in an autoimmune response to the normal eye. Although rare, the consequences can be devastating for the normal eye.1 In addition, blind eyes after trauma often become painful and do not look normal, giving additional reasons to consider an enucleation.
The procedure is usually performed under general anesthesia, although it can also be performed with the patient sedated (Figure 1). A retrobulbar block is given prior to starting the surgery to help with postoperative pain and to help prevent bleeding during the surgery with the use of epinephrine in the injection. For eyes with tumors, some surgeons prefer to not give a block because of the risk of perforating the eye with the needle.
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.
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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
Evisceration
For an evisceration, the contents of the eye are removed and the sclera is retained (Figure 3). Eviscerations are often performed for blind, painful eyes. Eviscerations are not performed for eyes that have tumors; in fact, it is mandatory to image (ultrasound) the eye prior to an evisceration to make sure there is not an unknown or undetected tumor.4
Advantages of evisceration are faster surgery (<30 minutes) and less manipulation of the orbit with extraocular muscles left in their normal anatomical position. In addition, research has shown that the movement of the prosthesis is better after evisceration compared to an enucleation.5 Disadvantages include a theoretic concern for sympathetic ophthalmia (extremely rare) and a poor anatomic specimen for the pathologist.
This surgery can be performed with the patient awake or asleep. An incision is made 360°
posterior to the limbus, and the cornea is removed. An evisceration spoon is used to remove the contents of the eye so only the sclera remains. An implant is placed within the scleral shell or behind it, and the sclera and conjunctiva are closed over the implant.
Postoperative care is similar to an enucleation. Complications are fewer with an evisceration compared to an enucleation. There is a lower incidence of implant exposure, and volume problems are less common.
Exenteration
In exenteration, the entire eye is removed as well as the soft tissue of the eye socket (Figure 4). This is a disfiguring surgery and usually performed when the patient’s life is at stake. Indications include malignant tumors and extensive infections of the orbit. Skin cancers (e.g., basal cell carcinoma, squamous cell carcinoma) that have invaded the orbit, primary malignant tumors of the orbit, and malignant sinus tumors which have invaded the orbit are indications for exenteration, although recent advances with molecularly targeted agents are resulting in fewer exenterations.6
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An exenteration is performed with the patient asleep. An incision is made through the skin, and dissection is carried out to the underlying orbital rims. The covering of the bone (periosteum) is elevated from the bone completely around the orbit, and the orbital apex is transected with scissors to remove the orbital contents. The socket can be allowed to granulate, or a split thickness skin graft or free flap can be placed depending on a number of factors. Sometimes enough skin can be retained from the eyelids to cover the bare bone.
The patient can be fitted with an oculofacial prosthesis after the surgery. This prosthesis differs from the prosthesis after an enucleation or evisceration because the eyelids do not blink and the eye does not move.
Postoperative care
After any of the above procedures, it is important to take more time postoperatively with the patient, who is understandably anxious about how things will look and whether there will be pain.
It is important for patients to wear glasses with polycarbonate lenses after any of these procedures. This will protect their only eye from an incidental trauma, and the glasses will camouflage any asymmetry.
Overall, I have found that results from nucleation, evisceration, and exenteration are excellent. I can promise that all of us have met a person with an artificial eye that we did not notice.
References
1. Galor A, Davis JL, Flynn HW Jr, Feuer WJ, Dubovy SR, Setlur V, Kesen MR, Goldstein DA, Tessler HH, Ganelis IB, Jabs DA, Thorne JE. Sympathetic ophthalmica: incidence of ocular complications and vision loss in the sympathizing eye. Am J Ophthalmol. 2009 Nov;148(5):704-710.
