To view the creation of a custom built ocular prosthesis, please refer to the above video. Alternatively, below you will find a description of the procedure.
Indications for an Ocular Prosthesis
Generally the need for an ocular prosthesis will arise from one of two reasons, either congenital or an acquired problem.
A Bio-eye ocular implant is surgically placed within the orbit at the time the eye is removed, and the tissues are closed over the implant.
A temporary conformer is then placed over the implant and under the eyelids to maintain the space for the artificial eye. Six to eight weeks later, a visit is made to an ocular prosthetist such as Kanti Fatania at Hollands of London. The procedure involved in making an artificial eye takes time and will require multiple appointments in order to achieve the optimal results. This highly skilled specialist will create a detailed artificial eye, which will replicate your natural eye. The artificial eye will move as the implant moves or "tracks" along with the natural eye. Fitting the ocular prosthesis or artificial eye begins with the prosthetist making a mould of the eye socket.
Types of Ocular Prosthesis
Prosthesis is an artificial device which is used to replace a missing body part. It can be used to improve the cosmosis in the orbital region and can generally be classified as an ocular or orbital prosthesis. They can be either a stock item or custom made specifically for the patient.
Prerequisites for Fitting
There are certain prerequisites for an ideal prosthetic fitting. These include
- Deep forces in all quadrants,
- Normal tear secretion
- Effective volume replacement with orbital implants
- Adequate orbital fat
- Well-centered and covered orbital implant
- Absence of socket inflammation
Custom versus stock prosthesis
The recommendation for the patient is often that of a custom moulded prothesis, which allows even distribution of volume and weight in the socket giving better cosmetic and less discomfort to the patient. Being that it is specifically made for the patient it will in the short and longer term provide a more comfortable and pleasing result.
A stock prosthesis and surface can lead to unequal weight distribution and/or constant irritation of the surface. In the long term, this presents itself in the form of chronic discharge and laxity of the lower eyelid.
Steps in the Procedure
The procedure for creating a custom made prosthesis is as follows:
1. Examination by the oculist
2. Taking an impression of the eye socket
3. Acrylic model for the socket
4. Centration of the iris
5. Fabrication of iris and pupil to match the fellow eye
6. Moulding in acrylic
7. Tinting to match the scleral shade
8. Packing with the clear acrylic
9. Polishing
10. Instructions about hygiene and care of the prosthesis
The Examination and Taking an Impression of the Eye Socket
An initial examination of the patient will take place. This will involve taking an impression of the eye socket using acrylic materials. This will require the patient to be sitting upright and looking upwards steadily as this will make the process easier and create a more accurate and well fitting impression of the eye socket. The mixture is placed in a syringe with the help of a flat spatula. Whilst placing the moulding shell on the eye the patient is instructed to have a down gaze. The upper lid will be retracted and the shell is initially inserted underneath the upper eyelid followed by the lower eyelid. The moulding material will gel in approximately 2 minutes.
Once this has been done both eyelids will be gently retracted and shell will be removed from the socket and immersed in water.
The patient should be reassured that taking an impression is less uncomfortable than one might expect. The patient must keep the normal eye open and fixate on a predetermined point straight ahead whilst the ocularist is taking the initial impression. This will assist in ensuring that the patient will achieve maximum comfort and movement.
Additionally they will take measurements and comparisons to the natural eye to match size and colour of the iris, pupil and other features in order to achieve a desirable match for the patient. The proper shape for the artificial eye is also determined, and then the next step is artistic duplication of the eye colour. Once this has been done the ocular prosthesis is created using state-of-the-art materials. The prosthetist will build up iris colouration in a way that duplicates the natural iris pigmentation and texture. When the colour is judged to be correct, the eye is returned to the final mould and the layer of transparent acrylic is cured onto the front surface to protect the colour during polishing and wearing.
Creating an Acrylic Model
The ocularist will create an acrylic model (or in some cases a wax model) by mixing water and alginate. This paste will then be poured into a plastic cup and the rear surface of the impression. It will harden in 2-3 minutes. The alginate mould is then cut along the lines drawn on the impression tray. Polymerized acrylic is then poured into the impression mould and left to harden. The ocularist has now been provided with an exact replica of the socket impression. Once this light bodied silicon model has been made, the next task is to achieve centralising the iris so that it will provide a realistic look in symmetry with the other eye and complement the prosthesis. The model will be inserted into the patient's socket where the ocularist will then measure and mark out where the iris will be placed on the prosthesis. Additionally they will also use this opportunity to colour match the iris to once again ensure an accurate match.
Glass was once the preferred prosthetic material, but owing to difficulty in moulding and its fragile nature it is seldom used today. However glass eyes are still fabricated in some parts of Europe. Modern ocular prosthesis is fabricated using acrylic polymers of different qualities, which make it the material of choice for creating artificial eyes
Silicon is the material to use in fabricating the orbital prosthesis with the periocular skin and pattern. It is non- reactive, moulds easily and above all the desired skin texture can be created over the surface.
Centration of the Iris
An experienced ocularist is able to then get the centration of the eye, the tilt, and gaze and palprabral aperture through assessment. Kanti Fatania has been working in the field of artificial eyes for over 20 years and is well versed and experienced at achieving this effectively to patients' satisfaction.
Refining the Prosthesis
Once cured (hardened) the prosthesis is taken out from the mould and the edges are trimmed and neatened, then it can be polished and inserted into the patient's socket. While doing so the ocularist will reconfirm the size, plane and angle of the iris in the white base. If satisfactory symmetry and cosmisms are visualized, the corneal button is then defined and the process of tinting is begun. Cotton rayon threads are used to give the appearance of blood vessel appearance. Dry stable natural fine grinded colour pigments are used to give the exact shade to the sclera corresponding to the patient's fellow eye. Once it is ensured that the exact colour matching has been achieved the base of the prosthesis is kept in the oven at 85 C for 1 hour. This cures the colours to saturation levels and prevents any future fading. Once the artwork is completed, the shell is put back into mould and a layer of clear plastic is polymerized on the front surface, completing the fabrication process after trimming.
Using the dental grade two plaster and mixing it with a solution (a fine mixture of Plaster of Paris with water), invest the mold stem straight a head, in the centre of metal mold; (b) apply the cold sap (create a thin film in order when the other part of the mold is made should not stick together; (c) close the other face of the mold) (d) pour the dental stone on the hole of the mold on a vibrator so that all the possible air bubbles will come out and a smooth bubble free mold call be achieved. Once plaster is set the mold can be opened and the acrylic model can be taken out; white duff of the acrylic be placed on the iris corneal unit to achieve a nice nimbus blend; enough duffle placed on the back of the button; on the back surface of the mold we use dental dam which will provide the smooth back surface, very useful in the undercut back surface where polishing is very difficult; once you press excessive material is comes out and canoe taken off; the mold will then be placed in the metal clamp to give adequate pressure; curing takes place with polymel at 100 C temperature.
During this stage they will probably need to put the eye in and take it out a few times to make sure it fits properly. Finally when they are satisfied with the size and shape the prosthetist will polish the eye and fit it for you to wear.
Once your prosthetist has properly fitted the artificial eye, the full benefits of the Bio-eye ocular implant will be available to you. Of course, the final results in each case will vary depending on the condition of the orbit, muscles and surrounding tissues.
If the finished, highly polished prosthesis is not correct in every way from Hollands of London, we will make the necessary changes until it is impossible to improve the eye any further. While this method is more time consuming than many other eye fitters, we feel that this is the way we can best produce a superior prosthesis.
The Process of fabrication of a custom made ocular prosthesis.
Over time, the surface of the prosthesis collects protein and debris. Taking good care of your prosthesis helps to ensure a healthy socket and increase the life of your prosthesis.
Some patients find that removing and cleaning their prosthesis every day is necessary, while others are able to wear it for a couple weeks or longer before cleaning.
Cleaning the prosthesis every 2-3 weeks is the best time frame.
Always make sure that you wash your hands thoroughly before handling your ocular prosthesis. Use warm water to rinse and gently scrub the prosthesis, removing built-up pf protein and other debris. Then dry the prosthesis with a soft tissue or clean cloth, polishing very lightly in a circular motion.
Do not clean or soak the prosthesis in any solvents, disinfectants or alcohol. These chemicals can cause irritation to your socket or damage to the prosthesis itself.
Saline solution is okay to use as a substitute for water, but is not necessary.
A professional polish is the only way to remove the protein attachments and bacterial infiltration which will occur over time. It is recommended to have your prosthesis polished every 6 months. This can also assist in refreshing the prosthesis in general appearance as well. Please contact Hollands of London today to schedule an appointment if your last polish was over 6 months ago.
