The scleral shell

When a patient comes to you with a blind eye requesting removal of the eye, the first question to ask is, “Does the eye cause you pain?” If the answer is no, consider a scleral shell. A scleral shell is a thin ocular prosthesis that fits over the blind eye (Figure 16-1). The shell provides a natural appearance and is comfortable for most patients. No surgery is required to treat the patient. Patients who are ideal candidates for wearing a scleral shell are those with:

Figure 16-1 Scleral shell. (A) Painless small eye is a good choice for a scleral shell. (B) Comfortable scleral shell in place with natural appearance and reasonable symmetry.

Patients with severe pain probably will require enucleation or evisceration. You can sometimes treat patients for the mild aching pain that may accompany phthisis with prednisone ophthalmic (Pred Forte 1%) and atropine drops to control any intraocular inflammation. Undoubtedly, your enthusiasm for a scleral shell decreases as the complexity of any treatment to minimize pain increases. For many patients, removal of the eye is better than long-term treatment with drops and a shell, but at least consider the option of controlling mild pain medically. Most patients can tolerate the fit of a shell even with normal corneal sensation. Although the scleral shell sits over the eye, the posterior face of the shell is vaulted to sit off the cornea. If there is any question about pain, consider a trial period with a custom conformer. This prosthesis is custom-made to fit the shape of the socket, but does not have any color applied. The cost of the custom conformer is only 10–20% that of a completed prosthesis, so a trial is worth the cost if doubt exists that the shell will be tolerated. Although the scleral shell can be thin, an element of enophthalmos or phthisis makes it easier to get symmetry (Figure 16-1). Don’t recommend fitting a scleral shell if you think that the eye is continuing to shrink. In a few months, the shell will not fit and time and money will have been wasted. Obviously, enucleation should be considered for an eye with an intraocular tumor. Most patients wearing a scleral shell are blind in the eye that is covered. A patient with normal vision cannot see through the shell. For any patient with a disfigured iris who has good vision, a cosmetic contact lens (a special contact lens painted with matching iris details) should be considered.

Enucleation or evisceration?

Once the decision has been made to remove the eye, there are two options:

The enucleation operation removes the eyeball in its entirety. The extraocular muscles are cut off the eye, and the optic nerve is severed. The orbital contents are otherwise undisturbed. The evisceration procedure “eviscerates” or removes the contents of the eye. The sclera is opened, and the intraocular contents are scooped out. The extraocular muscles and optic nerve are left attached to the sclera.

The indications for enucleation are:

Most of the eyes that you are likely to remove will have been damaged by trauma. Occasionally, eyes may have been blinded by infection (endophthalmitis or corneal ulcer) or glaucoma. Choroidal melanoma is the most common intraocular tumor in adults requiring enucleation. Retinoblastoma is the most common intraocular tumor in children requiring enucleation.

Blind, painful eyes may be considered for evisceration instead of enucleation. Contraindications for evisceration are:

Evisceration does not permit a complete, controlled removal of an intraocular tumor. Surgical margins are impossible to evaluate. Eyes that are shrunken as a result of phthisis should not undergo evisceration because the sclera cannot hold an adequate-sized implant.

In the absence of tumor or phthisis, either enucleation or evisceration can be performed. So how do you choose? More and more, it has become the surgeon’s choice. It used to be said that the incidence of sympathetic ophthalmia was much higher with evisceration than with enucleation. This swayed the decision in favor of enucleation for eyes blinded by trauma or those having exposure to the S antigen through surgery or perforating corneal ulcer in an attempt to prevent sympathetic ophthalmia. Since that time, it has become increasingly apparent that the incidence of sympathetic ophthalmia is exceedingly low after evisceration.

Factors favoring evisceration over enucleation are theoretically better eye movements and less chance of postoperative enophthalmos, both owing to less disruption of the orbital tissues. Evisceration requires less operating time as well. For these reasons, many surgeons now perform evisceration in all patients without intraocular tumor or phthisis. It is said that evisceration does not eliminate pain in all patients because the posterior ciliary nerves are not cut. I don’t know if this is true. In my practice, a large percentage of the eyes that are removed are for choroidal melanoma, so we perform many more enucleations than eviscerations. The majority of eyes that meet the indications for evisceration are enucleated as well, mainly because of habit.

An important use for evisceration is for the blind, painful eye with severe conjunctival scarring, as in an alkali burn. Evisceration requires less conjunctival dissection than enucleation. This allows a more normal-sized prosthesis to be fit because the fornices are not shortened by tearing the conjunctiva when you try to free it from the eye.

You should know that many of my trusted colleagues have switched to evisceration whenever possible.

Preoperative considerations

Enucleation operation

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 MEDPOR SST spherical implant includes:

• Patient preparation

• Detaching the extraocular muscles

• Severing of the optic nerve

• Inserting the implant

• Attaching the muscles to the implant

• Closing in layers

The steps of the enucleation operation with placement of a MEDPOR PLUS SST spherical implant are:

1. Prepare the patient

A. Develop a preoperative routine ensuring that you will 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 will be operated on. Place a mark on the patient’s forehead on the side that will be operated on. Tell the patient why you are placing the mark.

(3) In the operating room, confirm which eye will be operated on (a “time-out”).

(4) And lastly, look into the dilated eye to ensure that there is a pathologic process present (Figure 16-2, A).

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

B. Administer anesthesia

(1) The majority of patients will be under general anesthesia.

(2) Inject local anesthetic with epinephrine under the conjunctiva for hemostasis before you scrub (Figure 16-2, B).

2. Detach the extraocular muscles

A. Begin the procedure with a 360 degree peritomy using Westcott scissors (Figure 16-2, C).

B. Dissect Tenon’s capsule away from the eye using curved Stevens scissors, spreading in each quadrant between the rectus muscles (Figure 16-2, D).

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) (Figure 16-2, E). 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 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 (Figure 16-2, F).

(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) (Figure 16-2, G). 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 (Figure 16-2, H).

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 (Figure 16-2, I).

(3) If the clamp is in the proper position, there will be no bleeding.

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

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 will be no bleeding.

H. Put a damp gauze pad into the wound.

4. Insert the implant

A. Most patients will require a 20 mm spherical MEDPOR implant. Open the sterile wrap and color the side of the smooth side of the sphere with a marker. Put the implant in sterile saline.

B. It is important to fill the implant with saline. Take the end off a 35 cc syringe and drop it into the barrel of the needle as a spacer. Then place the implant in the syringe and aspirate saline. Expel any air from the implant with repeated “washes” of the implant.

C. Place the implant “colored side up” in the introducer (Figure 16-2, K). With upward traction on the rectus muscle sutures, push the introducer deep into Tenon’s space (Figure 16-2, L).

D. After placing your index finger on the implant, slowly withdraw the introducer (Figure 16-2, M). 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 insure that the implant is deeply placed. The edges of Tenon’s capsule should meet over the implant with little tension.

E. If there appears to be tension on the closure, remove the implant and try again. If tension remains, you will 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 backwards through the implant (Figure 16-2, N). The 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.

B. Close the conjunctiva using a running locking 7-0 Vicryl suture (Ethicon TG140-8) (Figure 16-2, O).

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 (Figure 16-2, P).

B. Tape a pressure patch over the eye. Leave the patch on for 24–48 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 medications are appropriate for 24–48 hours. After removing the patch, the patient should use topical antibiotic ointment tid.

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