An ocular prosthesis is an artificial eye implanted into the socket to replace a natural eye that has been removed. Usually referred to as a fake or glass eye, the shell resembles the eyeball and is used to cover the structures in the socket. The implant functions as the natural eye since it supports the proper functioning of eyelids.
An eye can be removed following severe trauma to the eye, congenital (birth) abnormalities or malformations, infections, tumors, and painful glaucoma that cannot be treated. Losing an eye may psychologically affect a patient. Therefore, an ocular prosthesis is fabricated to restore the eye's function, structure, and cosmetics. Often, the outcome of surgery involving an ocular prosthesis is good. However, a prosthesis eye does not provide vision.
There are two types of ocular prosthesis; ready-made (stock) and custom-made. These cater to the economic needs of each patient. Ready-made prostheses come in standard shapes, sizes, and colors and can be used for an interim or a postoperative purpose. Custom-made prostheses carry certain advantages such as comfort, enhanced aesthetics, even distribution of pressure, etc.
The materials used to fabricate an ocular prosthesis include metal, silicone, hydroxyapatite, and plastic acrylic. A prosthesis made from plastic acrylic is solid compared to the glass prosthesis because the material is lightweight, adjustable, translucent, and unbreakable. It is also easy to fabricate, easy to fit, and contains excellent coloring capabilities.
A prosthesis implant is essential for:
- Improving mobility
- Replacing lost tissue volume
- Improving the cosmetic appearance of the eye
- Preventing eye tissue from growing and filling the empty space
Surgery Involving an Ocular Prosthesis
Prosthetics are fitted after a patient undergoes eye removal surgery. There are three types of surgery that determine which prosthetic eye the surgeon will opt for. They include:
- Evisceration where an incision is made in front of the eye, and the jelly-like tissue inside the eye is suctioned out. This procedure preserves the sclera (white of the eye), which is then used to cover the implant placed into the eye socket. It has a more rapid recovery time compared to the other two procedures.
- Enucleation where the eye is removed, including the sclera, but the muscles and orbital contents are left intact.
- Exenteration which involves removing the eyeball and other eye contents completely. This process is usually performed in cancer cases.
During these surgical procedures, the surgeon places a temporary, transparent, plastic 'shell' behind the eyelid to prevent the eye socket from contracting (widening) in the first few weeks after surgery. The choice of procedure to perform depends on the degree of damage to the eye and the patient’s type of condition.
Once the eye has been removed, the surgeon deeply and permanently places an ocular implant to replace the eye and covers it with conjunctival tissue. The eyelids are stitched together over the eye implant and plastic shell for two weeks following surgery. The surgeon covers the eye socket and gives it some months to heal. They will later fit over the implant and under the eyelid, a stock prosthesis, which takes the shape of a convex shell.
Once healing is complete, usually between six to 10 weeks after surgery, the specialist uses form material to make an impression of the eye socket to fabricate a prosthetic eye. The artwork follows where blood vessels and a new iris are painted by hand on the white part of the eye. It takes at least six weeks to make a custom-made ocular prosthesis after surgery and up to three fittings before the final fitting. Typically, the ocularist does the fitting on the first visit, artwork on the prosthesis on the second visit, and a final fitting on the third visit.
To help with eye movement, the surgeon covers the eye implant with eye tissue. S/he then connects the eye tissue to the existing eye muscles to enable the patient to experience natural eye movement. Eye movement may however not be as complete or brisk as happens with a natural eye. Because the pupil is not real, it will not constrict (narrow) naturally. Therefore the two pupils may seem unequal.
Risks, Side Effects & Complications
Like any other surgery, any surgical procedure involving the eye carries certain risks. Evisceration surgery carries the risk of inflammation through sympathetic ophthalmitis. The inflammation can lead to loss of vision if not treated.
Infections can arise during surgery but can be treated with oral and eye drop antibiotics.
Side effects include pain, swelling, and nausea in the first 72 hours after surgery, which can be treated with strong pain relievers.
In the initial days of wearing a prosthetic eye, the patient may experience discomfort or tightness in the eye, but will over time get used to it.
The overlying tissue of the implant may become eroded, leading to the implant's exposure. The implants can also get contaminated.
After Care & Follow Up
The patient needs to take oral antibiotics for several days after prosthetic eye surgery. Antibiotic eye drops must also be taken for a few weeks. One should return to the surgeon two weeks after the procedure for the removal of stitches.
Patients need to exercise caution and care with the prosthesis. Care involves regularly cleaning the ocular prosthesis, maintaining moisture, polishing it, and visiting the ocularist. It is recommended that the prosthetic eye be thoroughly cleaned with soap and water and well-dried before being placed back into the eye socket. Ocularists recommend the use of a plunger to place the prosthetic eye back into the socket. It is okay to sleep with the prosthetic on, unless the doctor has advised against it. The prosthetic eye can be removed and replaced when needed.
The patient is advised to desist from frequently removing the prosthetic eye and to use lubricating eye drops over the ocular prosthesis. Patients should also remove any debris from the prosthesis. An annual polish by the ocularist is recommended as well as replacing the ocular prosthesis every five years.
Recovery & Results
Individuals can still engage in normal activities like showering, swimming, and skiing with a prosthetic eye. They can also have teary eyes since tears are secreted in the eyelids.
Those who have suffered from retinoblastoma, anophthalmia, and microphthalmia, register a better quality of life with ocular prostheses.
It takes about three to four months for complete healing to occur. The socket's shape may continually change, necessitating additional fitting and adjustment, even months after the initial procedure.
It is also advisable that a patient who has lost an eye and is fitted with a prosthetic eye undergoes counselling and engages in support groups to address the psychological disturbances that may arise.