Artificial Eyes and Eye Removal

Each year in the United states there are approximately 5,000 eyes removed for serious eye problems. Most often the eye is removed because of an accident such as a BB gun injury to the eye and less often the eye is removed becasue it is extremely painful from endstage glaucoma or inflammation or the eye contains a malignant tumor. ONce the eye is removed (enucleation or enucleated) an artificial eye (prosthesis) is placed. Nowadays we are able to make an artificial eye move so that it appears that it is seeing. Certainly the artificial eye cannot see but the movement of the artificial eye along with the normal eye gives the impression that the artificial eye is seeing.

The eye is housed in an area called the orbit. After an eye is removed an implant is placed to replace the lost volume. The first orbital implant was placed in the early 1900's and it was a glass sphere. Later, spheres made of wire mesh, silicone, hard plastic and even charcoal were used as orbital implants. In the 1940's and 1950's there were several implants designed to make artificial eyes move but these were only moderately successful. In the 1970's hydroxyapetite was first used by orthopedic and maxillofacial surgeons to rebuild broken bones, especially after trauma. In the 1980s it was used by eye surgeons after enucleation. The beauty of this implant is that it becomes a "living" part of the body because it becomes integrated with the patient's own blood vessels and thus is protected from problems associated with other implants such as infection and extrusion. The benefit of this implant is that it moves in the patient's orbit and can eventually move the overlying artificial eye.

How is Enucleation (eye removal) Done?

Removal of the eye is termed enucleation. There have been many variations of this technique over the past 150 years. Presently the surgery is usually done under general anesthesia with the patient deeply asleep.The eye is carfully prepared and the tissue on the surface of the eye (conjunctiva) is entered. All of the six muscles that move the eye are identified and retracted from the eye. The optic nerve is then cut and the eye is removed intact as a sphere. The blood vessels, nerves, muscles, and tear gland remains in the patient. The eyelids are not cut. When the patient wakes up from surgery, the area has a large patch and this is removed 24 hours later. The eyelids are closed.

Two to six weeks later, after the healing is nearing completion, an artificial eye is fit by an ocularist. The ocularist is an artist who carfully studies the remaining eye and designs an artificial eye to exactly match the remaining eye. The artificial eye remains with teh patient forever and is worn at all times - during sleeping, swimming, and other activities. It may need to be washed once a month or less and it may need to be modified as the patient ages.

Most patients with an artifical eye do not even feel the eye. Initially it may feel "funny" as one may feel a new filling in a tooth. eventually the patient adapts and does not realize that the prosthesis is in place. Some patients develop an allergy to the prosthesis and need to take eyedrops. Others may need eyedrops to lubricate the prosthesis. Infections caused by the prosthesis are rare.

Hydroxyapatite Implants

Hydroxyapatite is a sterile material obtained from reef building coral. It is very brittle, light in weight, and porous. Hydroxyapatite is wrapped with a smooth coat of sclera so that it moves and slips easily within the orbit. Once the eye is removed, the implant is placed at the same surgery. All 6 muscles of the eye are attached to the implant in their normal anatomic position so that the implant looks like a buried eye. This allows for the implant to replicate the motion of the natural eye. It stays in the orbit forever and does not need to be replaced, even those that we place in infants. Should the patient want more movement of their artifical eye, the implant is drilled at least 6 months after its placement and a peg is placed into the implant. This peg is then connected to the artificial eye so the muscles move the implant that move the peg also move the aritificial eye.