Artificial eyes and orbital implants

Removal of an eye is known as enucleation and is generally carried out when a patient has suffered a severe trauma, particularly where the eyeball or globe has been ruptured and it's unlikely that sight will be recovered. There may also be concerns about a rare condition called sympathetic ophthalmia, where the good eye becomes inflamed after the affected eye is damaged.

In some cases, enucleation is recommended if a large eye cancer cannot be removed or destroyed, or where treating the cancer leaves the patient with little or no sight and a permanently painful eye.

Removing the contents of an eye only, which leaves the outer coating of the eye attached to eye socket muscles, is called evisceration.

Implants are used to replace either the entire eye or to fill an eviscerated eye.

Orbital implants

There are two types of eye implant, integrated and non-integrated.

Non-integrated implants are usually made of a solid material, such as polymethylmethacrylate (PMMA), which is a type of acrylic plastic — Perspex is made from a type of PMMA.

When a non-integrated implant is fitted into the socket, the eyeball muscles and soft tissues surround it. After healing, a prosthetic or artificial eye, which looks like a big contact lens, is placed over the implant. When the muscles move the implant, the artificial eye moves too. Nowadays, non-integrated implants are wrapped in a mesh, to which the muscles are attached, reducing the risks of drifting or rejection (known as extrusion or being pushed out of the socket).

Integrated implants are made of permeable material, such porous polyethylene. These allow the tissue in the eye socket to grow into the implant, which effectively makes it part of the body.

One of the most interesting types of integrated implant has been developed from coral. The mineral in coral is processed to match human bone and is called hydroxyapatite, or HA. This means that the body accepts it as part of itself.

The eye muscles are attached to an HA implant using a mesh that slowly dissolves as the muscles bond to the implant. Newer HA implants are being developed that do not need mesh — the muscles are sewn directly onto the surface. After healing, the artificial eye (or prosthesis) is fitted and inserted. The artificial eye can also be pegged on to the orbital implant, which allows them to move more than they otherwise would. However, many patients are happy without pegs. Disadvantages of pegging include potential complications such as infection. In some cases, a pegged implant can make a clicking noise when the eye moves. Pegging is carried out approximately a year after an HA implant has been inserted. HA implants with well-fitted artificial eyes can be so good that they are almost indistinguishable from real eyes.

Integrated implants tend not to extrude or be rejected by the body and have a low risk of drifting. They may, however, have a greater likelihood of being exposed because of a breach of the lining of the sock (the conjunctiva) and if so, will require further surgery, ranging from a patch graft or even temporary removal. They can be used to replace other forms of implant, at enucleation or afterwards.

Integrated implants are more expensive than other types of implant and may not be suitable for patients with severe contractions of socket tissue caused by serious infection or injury, or whose sockets have been damaged by radiotherapy.

Regardless of the type of implant, the tissues in the socket tend to shrink over time. This is rectified by using larger artificial eyes but these can give the wearer less eye movement and lead to drooping of the eyelids, or ptosis. As a result a few — less than ten percent — of patients ask for additional surgery to improve the look of their eye.

Procedure

An orbital implant is placed in the orbital cavity when the eye is removed and the tissues are closed over the implant. A temporary plastic disc (a clear conformer) is fitted on top of the implant for a month after surgery to prevent the socket shrinking.

Two months or more later, the patient sees an ocularist, also known as a prosthetist, who will create a detailed artificial eye or prosthesis that matches the natural eye.

If further eye movement is wanted, Mr Malhotra can peg the artificial eye to the implant. Less than ten per cent of patients choose pegging. The procedure is performed in an operating theatre as day surgery under local or general anesthetic.

In this simple, optional procedure, a hole is made in the implant and a peg is inserted into the hole. Your ocularist then modifies the back of the artificial eye to accept the head of the peg and create a ball-and-socket joint. The procedure takes about 30 minutes. At first, a temporary peg is used. A permanent peg is put in place at another fitting. This may requite a general anaesthetic.

The peg-fitting procedure can only be performed after the implant has had time to fill with tissue from the orbital cavity — usually a year after insertion of the implant.

Before operation for orbital implant

After operation for orbital implant

What to expect

For the initial operation, patients are normally admitted on the day of surgery and discharged the next
Most people experience some pain for a day or two, though about ten per cent of patients find that pain lasts for a few days and is quite severe — standard painkillers are usually sufficient but stronger ones can be prescribed.
If a patient is in a lot of pain or, in rare cases, is sick, a second night in hospital may be advised.
Eye movement may cause most of the pain, so discomfort can be avoided by moving the head rather than the eye.
You'll wear a pressure dressing for a day to reduce bruising and swelling.
Tell family and friends, including children, that you will be wearing a head bandage and that your eyelids may be quite bruised when it's removed.
You can remove your own dressing to save a visit to the hospital and will be given written instructions on aftercare.
Most people do not return to work for at least a week. If you work in an unclean environment, it is wise to stay off work for longer.
You can camouflage the eye with dark glasses or tape stuck over the lens of a pair of ordinary glasses.
A temporary eye pad may be used but should not be worn continuously.
Your upper lid will initially be droopy but will begin to rise within a few weeks.
It takes at least eight weeks for the socket to heal fully and may take longer — only then can the prosthetist measure for the fitting of the artificial eye.
The prosthetist can also make a wax template for the surgeon to use to mark the correct position for a peg, if that is to be used.
You should have an annual check-up with your prosthetist, to assess any small fitting changes and polish your artificial eye to remove deposits and any scratches.
Your prosthesis will usually need to be replaced every two to five years, as your body is constantly changing, but this varies considerably from patient to patient.

All procedures begin with a consultation. For full information about what to do before and after surgery, see Patient information.