Enucleation is a surgical procedure where the entire globe (eye) is removed with its intraocular contents and the scleral shell. The procedure detaches the extraocular muscles to remove the eyeball but spares all other periorbital structures.
Reasons for eyeball removal are often drastic such as malignant tumors (ocular melanoma, retinoblastoma, etc.), trauma, and diseases like glaucoma and diabetic retinopathy. Others include a blind, painful eye, a degenerated eye, microphthalmos (both eyes abnormally small), and multiple ocular surgeries. Sympathetic ophthalmia (uveal tract infection affecting the eye that is not injured) may also cause an enucleation.
However, surgery is undertaken to alleviate pain, treat certain eye diseases, and improve the quality of life. After enucleation, the patient is fitted with an ocular prosthesis (artificial eye) for cosmetic purposes.
Preparation & Expectation Before Surgery
Removal of an eye is psychologically disturbing for the patient. This is after a patient’s mental status has been altered following trauma. Therefore, the doctor needs to create a plan for eye removal and take time to explain the options, risks, and benefits. Most surgeons consider closing the open globe as a primary measure rather than perform an enucleation. Enucleation can later be an option if there is evidence that the eye is severely disfigured or is no longer perceptive to light. The doctor takes the patient through the pros and cons of enucleation and risk of sympathetic ophthalmia that might affect the other eye. Thus, the patient is accorded sufficient time to consider the options.
Before the operation, the surgeon confirms the correct eye to be operated on and determines whether other medical issues need to be addressed preoperatively.
The patient must be accompanied by a driver and should not be alone for at least 24 hours.
Types, Purpose & Procedure
The doctor will administer general anesthesia and a regional anesthetic nerve block in the patient's retrobulbar space. The anesthetic will later help with the pain management and to control the bleeding. The doctor then drapes the patient in a sterile fashion.
In this outpatient procedure, the surgeon will:
- Make an incision at the limbus (a 360-degree peritomy) to reflect the conjunctiva and Tenon’s capsule using Wescott scissors.
- Dissect (blunt) each oblique quadrant of the sub-Tenon’s plane.
- Identify each rectus muscle, isolate it using a muscle hook, secure it with a suture, and cut at the globe’s insertion. Some surgeons opt to secure the muscles with sutures after eye removal.
- Isolate and transect the inferior and superior oblique muscles.
- Identify, strum, and cut the optic nerve once it has been established that the globe can rotate freely. The surgeon uses an enucleation snare wire or enucleation scissors to cut the optic nerve. Some surgeons first press the optic nerve using a curved hemostat (instrument to prevent blood flow) before transecting to stop further bleeding.
- Attempt to cut a long segment of the optic nerve, especially where intraocular malignancy is involved.
- Apply direct pressure in the intraconal space and perform cautery (burning) on the optic nerve if required.
- Place an implant in the intraconal space to replace the globe volume lost in the enucleation procedure. The implant enhances cosmetic symmetry and allows for prosthesis movement. However, the surgeon may be informed by certain circumstances like a severe infection, to place an implant in a subsequent surgery and not at the time of enucleation.
- Uses absorbable sutures to close two tissues, the Tenon's capsule and the conjunctiva, over the implant.
- Applies antibiotic ointment and places a clear plastic conformer over the now-closed conjunctiva to protect the socket and maintain the shape of the eye.
- Puts a pressure patch over the socket. If need be, the surgeon temporarily partially sews the eyelids together.
Risks, Side Effects & Complications
Excessive pus or discharge following infection should be a source of concern. A patient should seek medical attention in case of swelling, redness, never-ending intense pain, and fever.
Enucleation presents with complications before and after surgery. Before surgery, the surgeon can remove the wrong eye. There may be damaged extraocular muscles, hemorrhage, and a perforated eye. After enucleation, complications include enophthalmos (posterior eyeball displacement) and hollow/deep superior sulcus (depression).
Others include wound dehiscence (separation), infection (especially if the prosthesis is not regularly polished), conformer extrusion (being pushed out), fornices’ contraction, and the exposure, extrusion, and migration of the implant. The procedure can also result in hemorrhage, ptosis (drooping of upper eyelid), entropion (eyelid folds inward), ectropion (eyelid folds outward), poorly fitting prosthesis, inflammation of orbital tissue, and socket contracture (fixed tightening).
Several studies have reported that patients who have undergone enucleation exhibit significantly poorer implant motility (movement).
After Care, Recovery & Results
The eye is patched briefly following surgery. The patch helps to keep bruising and inflammation down and is removed a week after surgery. The patient must also keep the patch away from water so that it does not fall off. The patient can wear polycarbonate lenses to protect the seeing eye against accidents and trauma.
Antiemetics and analgesics medications are prescribed. Antibiotics (prophylactic) may be prescribed.
The swelling and bruising seen when the patch is removed will go away over the next few weeks. Sometimes the eyelid is sewn (tarsorrhaphy) to keep the conformer in place, and the eyelid should open by itself approximately one week following surgery. While wearing the conformer, the eyelid may seem droopy for the first few months.
Heavy lifting, bending at the waist, a dirty environment, and strenuous activities should be avoided for at least two weeks following surgery. Swimming is not allowed for at least three weeks, and the patient must heal for at least two months before prosthetics can be considered.
Patients return for follow up a week after enucleation. The next visit is a month or two later, when the surgeon may refer the patient for an ocular prosthetic fitting. Patients will regularly be followed up by an ocularist and oculoplastic surgeon to keep the socket healthy. The next follow-up appointment is six months following surgery and every six months thereafter. It’s important to have the prosthetic regularly polished by the ocularist.
Recovery will depend on the extent of the surgery. Some may stay in the hospital for a few hours while others for several days.
The advantage with enucleation is that in cases involving cancer, specimens can be examined under a microscope to determine malignancy margins and whether the optic nerve has been invaded. Enucleation also reduces the risk of developing sympathetic ophthalmia.