In medicine, enucleation refers to a surgical procedure in which a surgeon removes the entire eyeball from the eye socket or orbit. One of three possible procedures for eye removal, an enucleation is the procedure of choice for intraocular tumors. Other common reasons for enucleation include irrecoverable ocular trauma, severe inflammation, and uncontrolled pain in a blind eye. Ophthalmologists perform enucleations as a last resort in situations where the condition being treated cannot be suitably managed in any other way. Most patients who undergo enucleation obtain an artificial prosthetic eye to replace the extracted eye for cosmetic improvement.
The two most common ocular tumors requiring enucleation are retinoblastomas and ocular melanomas. Retinoblastomas are malignant tumors of the retina. Ocular melanomas can affect the colored part of the eye, the iris, or the vascular coat of the eye, the choroid. Melanomas derive from abnormal pigment cells, or melanocytes. When the tumors are very large and there is no prospect for useful vision, enucleation is performed to prevent local and distant spread of the tumors.
Another rare condition that requires removal of an eye is sympathetic ophthalmia. This is an inflammation of both eyes resulting from massive trauma to one eye. The body begins to mount an immune attack against the eye tissues of both eyes. The only way to treat the condition and spare the uninjured eye is to remove the injured eye.
General anesthesia, in which the patient is fully unconscious, is the preferred anesthesia for an enucleation. The surgeon dissects the orbital tissues, including the ocular muscles, away from the eye. The optic nerve is severed approximately one centimeter (0.45 inch) from the back of the eye. Once the eye is extracted, an orbital implant, consisting of hydroxyapatite or silicone rubber, fills the space in the orbit with the patient’s soft orbital tissues covering it. In order to enable some movement of the artificial eye, the surgeon attaches the eye muscles to the implant.
Once the patient has recovered from an enucleation, he can obtain a prosthetic eye. An ocularist is a technician who specializes in the design and customization of artificial eyes. He molds the back surface of the prosthesis precisely to fit the orbit of the patient. Prostheses can be painted to match exactly the fellow eye of the patient. The artificial eyes can last several decades.
The older models of orbital implants, typically plastic, do not move in concert with the fellow eye. Advances in the implants use porous material, which allows the growth of blood vessels and fibrous tissue into the implant. The attached eye muscles move the implants and the overlying custom-fitted artificial eyes. This produces a more natural appearance to the patient.