Enucleation, Evisceration, Exenteration, and Care of the Eye Socket

Goals

The goals of the enucleation operation are:

• ■

  Remove the eye

• ■

  Restore the orbital volume

• ■

  Provide movement to the ocular prosthesis

Removal of the eye is carried out in a routine fashion by severing the attachments of the extraocular muscles and optic nerve from the eye. The technique for controlled enucleation with minimal bleeding is described below. You must be careful when removing an eye with an intraocular tumor not to penetrate the eye with any needle. The goal of restoring orbital volume is usually met by placing an orbital implant. The majority of implants placed today fit within Tenon’s space in the same position as the eye. No doubt, many times the implant is pushed posteriorly into the intraconal space as it is placed. You should minimize the manipulation of the orbital fat to avoid postoperative fat atrophy. The movement of the implant and the conjunctival fornices pushes the prosthesis to provide natural eye movements within the conversational range (10 to 15 degrees).

The volume of the orbit is approximately 30 mL. The volume of the eye is 7.5 mL. The volume of the eye must be replaced with volume provided by the combination of the implant and the prosthesis. A 16-mm sphere replaces 2 mL of volume. A 20-mm sphere replaces 4 to 5 mL of volume. An average-sized prosthesis can make up for the additional 2.5 mL of volume lost during enucleation. In general, patients receive implants that are 20 mm in diameter. Occasionally, a 22-mm implant can be placed without undue tension on the closure.

Remember that any surgical trauma, such as retraction and cautery, can cause additional loss of orbital volume (the fat atrophy we mentioned above). Any loss of orbital volume occurring due to enucleation that is not replaced creates an enophthalmic appearance to the prosthesis, usually apparent as a hollowing of the superior sulcus. A larger-than-average prosthesis provides only a temporary solution because the lower eyelid cannot support the additional weight of the prosthesis and eventually sags. We discuss this problem later under Superior Sulcus Syndrome.

Timing of the Operation

When enucleation is planned for removal of an intraocular tumor, the procedure should be carried out as soon as possible after a systemic workup to rule out metastatic disease. When enucleation is planned after trauma to the eye, surgery should be carried out within 10 days. The risk of sympathetic ophthalmia following enucleation is close to zero if enucleation is carried out within 10 days. I am not aware of papers that prove this; however, it is the most commonly recommended timing.

Choice of Implant

With the introduction of the hydroxyapatite implant in 1985, a resurgence of interest in orbital implant design has occurred. Implants can be classified as:

• ■

  Buried or exposed

• ■

  Muscles attached or unattached

• ■

  Integrated or nonintegrated

• ■

  Porous or solid

A buried implant implies that the entire implant is covered with a closure of conjunctiva. Exposed implants were used primarily in the 1940s when a portion of the implant was allowed to project through an opening in the conjunctiva. This exposed portion of the implant was physically linked to or integrated into the prosthesis. These implants failed because of chronic infection and eventual extrusion. Almost all implants in use today are covered with conjunctiva or buried.

To provide the maximum motility of the ocular prosthesis, the extraocular muscles should be attached to the implant at the time of enucleation . The point of attachment is most commonly a direct suturing to a porous implant. An alternative is an indirect attachment by suturing the muscles to a covering over the implant such as human sclera or fascia, or Vicryl mesh. Some surgeons feel that a significant amount of movement of the ocular prosthesis is provided by movement of the conjunctival fornices. A minority of surgeons attach the extraocular muscles directly to the fornix rather than to the implant.

The term integrated implant was originally used to describe the attachment of a prosthesis to the implant. As was stated earlier, exposed implants were integrated directly to the prosthesis through an opening in the conjunctiva. This integration provided excellent motility of the ocular prosthesis (due to a lock-and-key fit of the prosthesis into the implant). Although the movement of these prosthetic eyes was excellent, infection was the rule because of the open conjunctiva. Experimentation with differently shaped implants led to the development of the quasi-integrated implant (the Iowa and the Universal Implants). These buried implants had an irregular anterior surface, projecting mounds on the surface of the conjunctiva. An ocular prosthesis was fit with impressions on its posterior surface to mesh or quasiintegrate with the prosthesis. Because there was no opening of the conjunctiva these implants did not become infected. These implants provide good motility, but they require more time to place and sometimes migrate or become rotated. I consider these implants to be a very viable choice; however, they have largely fallen out of favor.

Materials used in implant construction can be either porous or solid . Porous materials include hydroxyapatite and a high-density polyethylene material (SU-POR and MEDPOR products). The most common solid material for implant design is polymethylmethacrylate (PMMA). Porous implants have been popular choices for more than 20 years.

When introduced in the late 1980s, hydroxyapatite porous implants (coral) had the purported advantage of an implant that would allow blood vessels to grow into the implant over several months and become integrated with the orbital tissues. These implants would not rotate or migrate in the orbit. Beyond that the vascular ingrowth of the implant would allow a better version of the lock-and-key fit of the original exposed implants. After the implant was vascularized the surgeon drilled a hole into the face of the implant. The concept was that the conjunctiva would migrate along the side of the hole and survive due to the vascularization of the implant. A prosthesis was made with a peg that would fit directly into the implant. Now we had a true lock-and-key fit with a “buried” implant. For a time the oculoplastic world was abuzz with this new best-of-both-worlds implant. During this same decade, oculoplastic surgery, as a specialty, was flourishing with a new wave of young surgeons being trained. The new implant design with a new material combined with an enthusiastic group of surgeons led to a rapid adoption of this technology in hopes of benefiting patients wearing prosthetic eyes, who had, more or less, been ignored by all but a few surgeons.

Unfortunately, for many patients, the epithelium surrounding the insertion of the peg into the implant was not able to withstand the pressures created by the eye movements. Not infrequently, exposure and problems with granulation tissue occurred at the junction. Several revisions of the integration have not solved these problems. Consequently, most surgeons have abandoned any attempts at pegging or integrating a hydroxyapatite implant with the prosthesis.

Porous polyethylene spheres were introduced as an alternative to hydroxyapatite implants. Tissue ingrowth prevents implant migration, as with other porous implants. Porous implants appear to have a lower exposure rate than hydroxyapatite, perhaps due to a smoother anterior surface. For a short time, in hopes of finding a reliable method of attaching the implant to a prosthesis a titanium screw integration system was introduced, but it did not gain wide acceptance. I do not use hydroxyapatite implants.

Synthetic hydroxyapatite and other ceramic materials continue to be tested as implant materials. A few surgeons still peg porous implants with reasonable success owing to diligent attempts at revisions as needed, but as a whole, pegging of porous implants has been abandoned.

There is no perfect anophthalmic socket implant. Everyone agrees that the implant should restore adequate orbital volume requiring at least a 20-mm sphere. Most surgeons would agree that the extraocular muscles should be reattached to the implant. There are differing opinions regarding whether porous or solid implants are best. My current personal choice for an ocular implant is a 20-mm porous implant with a smooth front surface and suture tunnels to attach the eye muscles to the implant. *

* SU-POR Quadro-Port Tunnel Sphere (16 mm #4036, 18 mm #4037, 20 mm #4039, 22 mm #4041) poriferous.com MEDPOR Smooth Surface Tunnel (SST-EZ) sphere (16 mm no. 80008, 18 mm no. 80010, 20 mm no. 80012, 22 mm no. 80014) cmfstryker.com

We use no integration of the implant and the prosthesis (no pegging). Movement is good in the conversational range (within 10 to 15 degrees of primary position). You could argue that using a porous implant when you are not pegging is an expensive alternative to a much cheaper PMMA implant. However, there is essentially no migration of the porous implants compared with the solid implants. The porous implants allow you to attach the muscles without adding a material to cover the solid implant. Ask your colleagues which implant they prefer, and then ask them why they choose one over another (the key to learning is the “why” part of the choice!).

There is a wide range of favorite implants on the part of surgeons for the anophthalmic socket. We can all look forward to new implant designs in the future as this area of surgery continues to evolve. For the most part, the problem of migration, sometimes seen with nonporous implants, is solved. Replacing the orbital volume is reasonable with current implants (20- to 22-mm sphere). If a deficit remains, additional orbital volume can be added later. There remain issues with the occasional exposure of anophthalmic implants (3% to 5%). Prosthetic movements are good, but not at the extremes. The movement of the socket tissue may be good; however, the prosthesis movement is limited by slippage of the prosthesis over the ball and the limitation of the prosthesis against the immobile tissues of the fornix. No doubt, improvements will continue. For now, patients are happy; the easiest way to see their prosthesis is in the mirror with the eyes fixed in primary position.

Anatomy

The eye sits within Tenon’s space. This fibrous capsule covers the anterior and posterior surfaces of the eye. As the rectus muscles extend anteriorly from the orbit, they penetrate Tenon’s capsule to attach to the eye. This point of penetration is the arbitrary division of the anterior and posterior Tenon’s capsule. The optic nerve enters the eye through the posterior Tenon’s capsule. The enucleation operation is performed within the relatively bloodless space of Tenon’s capsule. The rectus muscles are detached from the eye without disruption of the attachments of the muscle to Tenon’s capsule. The optic nerve is severed posterior to the globe, sometimes leaving a hole in the posterior Tenon’s capsule. The majority of ocular implants are placed within Tenon’s capsule in the normal anatomic position of the eye. When using 20-mm and larger implants there is likely to be some posterior movement of the implant through the posterior Tenon’s capsule even though most surgeons do not intentionally push the implant posteriorly. The eye muscles are attached in a near anatomic position to the surface of the implant or a covering over the implant. A layered closure of the anterior Tenon’s capsule and conjunctiva buries the implant.

Enucleation Procedure

Enucleation of the eye is most commonly performed under general anesthesia. In selected patients, the procedure can be performed using local anesthetic and sedation.

The enucleation procedure using a porous spherical implant with tunnels includes:

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  Patient preparation

• ■

  Detaching the extraocular muscles

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  Severing of the optic nerve

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  Inserting the implant

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  Attaching the muscles to the implant

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  Closing in layers

The steps of the enucleation operation with placement of the porous spherical implant are:

• 1.

  Prepare the patient.

  • A.

    Develop a preoperative routine ensuring that you remove the correct eye.

    • (1)

      Unless the eye is obviously abnormal, leave preoperative instructions to dilate the eye to be removed.

    • (2)

      Before surgery, visit the patient to make sure you know which eye on which to operate. Place a mark on the patient’s forehead on the side on which you will be operating. Tell the patient why you are placing the mark.

    • (3)

      In the operating room, confirm whether it is the right or left eye on which you will be operating (a time-out).

    • (4)

      And last, look into the dilated eye to ensure that there is a pathologic process present ( Figure 16.3A ).

      

    • (5)

      This may seem like a lot of trouble, but you must be sure in every case. Figure out the system that works for you.

  • B.

    Administer anesthesia.

    • (1)

      The majority of patients are under general anesthesia.

    • (2)

      Inject local anesthetic with epinephrine under the conjunctiva for hemostasis before you scrub (see Figure 16.3B ).

• 2.

  Detach the extraocular muscles.

  • A.

    Begin the procedure with a 360-degree peritomy using Westcott scissors (see Figure 16.3C ).

  • B.

    Dissect Tenon’s capsule away from the eye using curved Stevens scissors, spreading in each quadrant between the rectus muscles (see Figure 16.3D ).

  • C.

    Hook the extraocular muscles using a smooth von Graefe muscle hook followed by a Green muscle hook from the opposite direction to make sure that you have hooked the entire muscle.

  • D.

    Pass the typical von Pirquet suture through the muscle insertion. I use 5-0 Vicryl on a spatula needle (Ethicon J571, S-14 needle) (see Figure 16.3E ). I find the traditional strabismus technique in which the surgeon holds the muscle hook in one hand and the needle holder in the other hand to be cumbersome. This technique may be important for a strabismus surgeon where the muscle is sutured and cut in a precise position, but it is not important for enucleation surgery. I would suggest you try one of two options. Either (1) hold the muscle hook yourself and have your assistant load the second arm of the needle back-handed for you on an additional needle holder; or (2) have your assistant hold the muscle hook, leaving you two free hands to load the needle and manipulate the tissues.

  • E.

    Now cut the muscle off the eye, leaving a bit of muscle tendon on the eye, especially at the horizontal rectus muscle insertions, so you can place traction sutures at the horizontal muscle insertions later (see Figure 16.3F ).

    • (1)

      Detach all four rectus muscles in the same way.

    • (2)

      Tape the sutures to the drape as you proceed.

  • F.

    Hook the oblique muscles and cut them from the eye (near Tenon’s capsule, not at the eye) (see Figure 16.3G ). Hook the inferior oblique muscle in the inferior and temporal quadrants with the tip of the muscle sweeping from posterior to anterior toward the muscle as it leaves the lower lid retractors heading for the eye. Cauterize the inferior oblique muscle before cutting it.

  • G.

    Place 4-0 silk traction sutures at the muscle insertions of the medial and lateral rectus muscles. If you have left some muscle at the insertion, this is quite easy. By all means, do not penetrate the eye with a needle if you are removing a choroidal melanoma.

• 3.

  Sever the optic nerve.

  • A.

    Give traction on the globe, prolapsing it out of the conjunctiva.

  • B.

    Use Sewall retractors to retract the posterior Tenon’s capsule away from the globe, exposing the optic nerve. Wearing a headlight is essential for this portion of the procedure.

  • C.

    Use a long hemostat to clamp the optic nerve approximately 1 cm posterior to the eye.

    • (1)

      To apply the clamp, insert the hemostat with the blades closed. Tap the optic nerve from the inferior side. Next, tap the optic nerve from the superior side. Open the blades to surround the nerve and tap each side of the nerve with the open blade. Once you are sure that you are around the nerve, close the hemostat (see Figure 16.3H ).

    • (2)

      If you are removing an eye because of retinoblastoma do not clamp the nerve because the nerve stump is a surgical margin.

  • D.

    Cutting the optic nerve can be done in the same way.

    • (1)

      Tap the nerve from below and above. Open the blades and tap the nerve from above and below again.

    • (2)

      As you apply upward traction on the eye, push the scissors posteriorly and cut the nerve (see Figure 16.3I ).

    • (3)

      If the clamp is in the proper position, there is no bleeding.

    • (4)

      Any soft tissues clinging to the back of the eye can be cut with the enucleation scissors.

    • (5)

      If you are removing the eye for a melanoma, inspect the globe and make sure there is no extrascleral spread .

  • E.

    Before releasing the clamp, retract the tissues around the optic nerve with the Sewall retractors and visualize the cut end of the optic nerve in the clamp.

  • F.

    Use a bayonet bipolar cautery to cauterize the optic nerve.

  • G.

    Slowly release the clamp. In most patients, there is no bleeding (see Figure 16.3J ).

  • H.

    Put a damp gauze pad into the wound.

• 4.

  Insert the implant.

  • A.

    Most patients require a 20-mm spherical implant. Open the sterile wrap and color the side of the smooth side of the sphere with a marker (not absolutely necessary, but helpful). Put the implant in sterile saline.

  • B.

    Place the implant colored side up in the introducer (see Figure 16.3K ). With upward traction on the rectus muscle sutures, push the introducer deep into Tenon’s space (see Figure 16.3L ).

  • C.

    After placing your index finger on the implant, slowly withdraw the introducer (see Figure 16.3M ). Inspect the position of the implant. Using a hand-over-hand technique with Paufique forceps, pull Tenon’s capsule anteriorly over the sides of the implant to ensure that the implant is deeply placed. The edges of Tenon’s capsule should meet over the implant with little tension.

  • D.

    If there appears to be tension on the closure, remove the implant and try again. If tension remains, you need a smaller implant.

• 5.

  Attach the muscles to the implant.

  • A.

    Suture each of the rectus muscles to the implant by passing the needle backward through the implant tunnels (see Figure 16.3N ). The inked coloring on the face of the implant should help you see the holes.

• 6.

  Close Tenon’s capsule and the conjunctiva.

  • A.

    Close the anterior Tenon’s capsule using the same 5-0 Vicryl suture from the muscle sutures. Use interrupted sutures. If you see any gap in the closure, place another suture.

  • B.

    Close the conjunctiva using a running, locking 6-0 chromic or 7-0 Vicryl suture. (see Figure 16.3O ).

  • C.

    Inject local anesthetic with bupivacaine (Marcaine) into the retrobulbar space for postoperative pain relief.

• 7.

  Provide postoperative care.

  • A.

    Place topical ointment and a conformer in the conjunctival fornix (see Figure 16.3P ).

  • B.

    Tape a pressure patch over the eye. Leave the patch on for 24 to 48 hours.

  • C.

    In the recovery area, explain that a conformer is in place and that it may rarely come out. Offer to fog the patient’s lens with 2-inch translucent tape to cover the socket without drawing the attention of a pirate patch.

  • D.

    Inpatient or outpatient care is appropriate. Narcotic pain medication is reasonable for 24 to 48 hours. After removing the patch, the patient should use topical antibiotic ointment three times a day.

The patient should return in 1 week for inspection of the socket. A custom-fit prosthesis should be made when the swelling has totally subsided, usually 6 weeks after surgery. Sometimes it is helpful to have the patient and family visit the prosthetic laboratory when you schedule the operation, so they know what to expect ( Box 16.1 ). If you are new in practice, seek out your local ocularist and visit the laboratory. The trip is a learning experience. Your relationship with the ocularist is very helpful to you and your patients.