Customizing a Cryolite Glass Prosthetic Eye

PMMA is currently the most common used material for prosthetic eyes globally. However, in Germany, Austria, and Switzerland, over 90%of the ocularists are still manufacturing customized prostheses using cryolite glass from Turnia This video will demonstrate each step of customizing a cryolite glass eye in detail, and will give ophthalmologists better insights into ocularistic care. These insights will help to improve the essential and the professional collaboration between ocularists and ophthalmologists.

The major advantages of using cyrolite glass for manufacturing prosthetic eyes are the hollow and very lightweight design, the very smooth surface reducing socket inflammation, and good aesthetic outcomes with high levels of patient satisfaction. In addition, for manufacturing cryolite glass prosthetic eyes, only one appointment is needed. And after one hour, patients can leave the ocularist with a new prosthesis, while three to four appointments are required for PMMA prosthetic eyes.

To begin this procedure, select one of the half-done cryolite glass eyes based on which matches the iris color best of the patient's healthy fellow eye. Examine the fitting of the current prosthetic eye by letting the patient look straight ahead. Pay special attention to the retention of the prosthesis, the viewing direction, the motility, the eyelid contours, and the size and volume of the current prosthesis.

Then, remove the current prosthetic eye with the help of a contact lens suction cup for hard contact lenses. Examine the anophthalmic eye socket without the prosthesis, and pay attention to a potential inflammation of conjunctiva, the volume filling of the orbital implant, if the orbital implant is visible through the conjunctiva, and if the fornices and sulci are deep enough for a good fitting prosthesis. If there are any major concerns regarding one of these points, and examination by an ophthalmic surgeon should be performed before manufacturing a new prosthesis.

Next, use ocularist forceps to pick up the selected half-done cryolite glass eye, and pick up a hollow skewer with the other hand. Using a Bunsen burner, slowly heat both the eye and the skewer to 600 degrees Celsius, making sure to continually rotate the eye and melting the skewer to the open end of the glass eye. Working with the material of glass for eye prosthesis is quite critical.

A continuous heating, not over-heating, as well as a fluid work flow is important to prevent a temperature breakage in the process. After this, open the forceps and lay them down and continue heating the half-done glass eye. Use the healthy fellow eye as a model for the color, shape, and quantity of the conjunctival vessels, and draw the vessels on the white sclera of the glass eye with heated glass stems of different colors.

Heat the entire half-done glass eye while continuously rotating it so that the drawn vessels merge with the white cryolite glass producing a very smooth surface. Then, modify the shape and volume of the cryolite glass prosthetic eye by suction and by blowing into the mouthpiece. Keep rotating the glass eye in the flame of the Bunsen burner occasionally.

Use the old prosthesis as a template for this process, but modify the shape and the volume of the new prosthesis based on the findings of the previous examinations if necessary. Next, heat a transparent glass stem, and melt it at the pupil of the glass eye while continuously rotating the eye. While rotating the eye, melt the glass at the rear of the prosthesis, and reduce the volume of the rear by suction with the help of the mouthpiece so that the shape of the backside is nearly equal to the sample prosthesis or the desired shape.

Melt the glass stem at the front side away, and heat the front of the prosthesis again to produce a very smooth surface. Use the forceps to grasp the front side of the prosthesis, and form the final shape of the back side with the help of the skewer. Then, melt the skewer away.

Heat the entire prosthesis for fire polishing again, especially the back side. And make sure to rotate the prosthesis until the surface is very smooth all over. Place the smooth prosthesis into a heated metal container and let it slowly cool down.

After this, insert the prosthesis and check the fitting as previously described. If necessary, modify the shape of the prosthesis again using the same process. In this study, a hollow double-walled cryolite glass prosthetic eye is customized.

Optimal results include a new prosthetic cryolite glass eye that fits very well, is comfortable, has a good motility, and has an appearance, including the eyelid contour, that is nearly symmetrical to the healthy fellow eye. Here you see a sub-optimal result caused by a typical deep sulculus syndrome, which is very hard to handle. It's difficult to fill up the upper part of the orbit by the prosthesis alone since it is a combination of an orbital fat atrophy and superior muscle relaxation.

The prosthesis is comfortable to wear, but in order to achieve an optimal cosmetic result in this patient a surgical intervention is necessary. Beside the knowledge how to make and fit an ocular glass prosthesis, we always have to check the eye socket of the patient to see the possible changes within the past year because we have to alterate the new prosthetic glass eye based on the changes. In summary, producing a good fitting and looking prosthetic glass eye is just a matter of practice, and also a question of experience resulting in an over six years training period for ocularists in Germany.

This video gives ophthalmologists better insights into the ocularistic care of anophthalmic patients. And also shows some advantages of the use of cryolite glass for manufacturing a prosthetic eye compared to PMMA. However, some divergences have not been identified in detail yet, and especially the impact of the material should be addressed in future studies.

Nevertheless, I'd like to emphasize the great importance of a good interprofessional collaboration between ocularists and ophthalmologists in the clinical care of these anophthalmic patients.