Patent Application
20080046078
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawings.
The present invention provides a method for making an ocular prosthesis in which the prosthesis is fabricated from a non-toxic, biocompatible, silicone material. Prosthesis- or medical grade silicone is used as a base for the ocular prosthesis. The silicone material offers a soft and flexible alternative to known hardened ocular prostheses, and avoids certain shortcomings of the PMMA-based devices. For example, it is believed that an ocular prosthesis fabricated from medical grade silicone materials is not as porous and so does not host microorganisms that might be harmful to the patient's surrounding ocular tissue. It is also believed that the fabrication methods of the present invention are faster than methods of making PMMA based ocular prosthesis due, in one aspect, to faster curing times.
The ocular prosthesis 100 first comprises a sclera portion 110. The sclera portion 110 represents what is commonly referred to in lay terms as the “white” of the eye. The sclera portion 110 is preferably fabricated from a medical grade silicone. Alternatively, the silicone material may be a prosthesis grade silicone, an implant grade silicone that is biocompatible over a period of time.
The medical grade silicone is white-tinted, and is cured following a molding process as will be described further below. The sclera portion 110 is preferably a solid device. However, as shown in
The ocular prosthesis 100 also comprises an iris portion 120. The iris portion 120 is placed on the sclera portion 110. In one embodiment, the iris portion 120 is placed onto the sclera portion 110 manually by hand-painting. Preferably, silicone-base paints are used in order to create the appearance of a natural eye. In another embodiment, the iris portion 120 is created by printing a digital or other computer-based image in the appearance of a natural iris. In either embodiment, silicone-based paints may also be used to paint veins and other ocular features around the iris portion 120. In some processes, red cotton threading is mixed into the paint to create an even more natural appearance of the eye around the iris portion 120 as will be described further below.
In one aspect, the iris portion 120 and the sclera portion 110 are integrally formed. In other words, these two portions are not structurally distinct and are not formed via lamination or adherence. In this respect, the iris portion is preferably painted onto the sclera portion. However, the iris portion may be a printed disc that is adhered to the sciera portion 110. Alternatively, the iris portion 120 may be a painted acetate or acrylic disc that is laminated or adhered to the sclera portion 110.
The iris portion 120 further comprises a centrally-located pupil portion 122. The pupil portion 122 may be formed by creating a cylindrical depression within an annular region of the iris portion 120. The depression is then filled with a black-tinted silicone material.
According to one embodiment of the present invention, the ocular prosthesis 100 further comprises a transparent layer 130 of silicone material covering the sclera portion 110 and the surrounding iris portion 110. In this way a protective coating is provided over the ocular prosthesis 100 and iris portion 120. The transparent layer 130 also provides depth to the prosthesis 100.
Finally, a clear and glossy finish is preferably provided over the ocular prosthesis 100. In one aspect, a clear layer of silicone 130 is brushed onto the prosthesis 100 at a thickness of 1/16 inches. The clear layer of silicone 130 substantially covers an outer surface of the prosthesis 100.
In order to form the ocular prosthesis, an impression of an eye socket of the patient is made. This may be in accordance with known prior art steps.
In order to create an ocular prosthesis such as prosthesis 100, an impression is made of the patient's ocular socket 62. The impression is made using an impression material. The impression material may be an alginate. Alginate is a non-toxic, non-allergenic molding material. The impression material is placed into the patient's eye socket 62 using a syringe 64 or other injection device.
In some processes, dental gypsum is used to obtain a positive cast or mold from the impression. A wax material such as a dental base plate wax or inlay wax is then shaped onto the gypsum cast to achieve an empirical approximation of the anterior portion for the future prosthetic. This is known as a model or “master.” The master has the size and shape necessary for the prosthesis 100. The impression material typically solidifies to the consistency of the white of a boiled egg to form a custom master of the ocular prosthesis 100.
The master may be trimmed and further fitted to the patient's actual socket 62. The master may be modified in order to achieve patient 60 comfort. The master may also be modified for appropriate anterior/posterior dimensions, anterior curvature, eyelid symmetry, and iris center position. The master is also preferably fitted with a temporary iris disk. Indications of the proper placement and size of the iris and pupil are marked manually on the master in reference to the natural eye, and a corresponding hole is created on the master for the pupil. The master is then placed back into the patient's eye socket 62 to confirm the fit and orientation of the master as well as the disk. The master is then removed from the socket 62 and any final adjustments are made in the pliable wax material.
Once the master is finished, a two-part plaster mold is created from the master to generate the prosthesis 100. The two-part mold consists of a posterior portion and an anterior portion. The mold defines a shell or “negative.” The posterior and anterior portions may be clamped together during a molding process in accordance with existing technology.
A method for making an ocular prosthesis such as prosthesis 100 is also provided herein. The method uses a mold such as mold 30 for forming the prosthesis 100.
In one aspect, the coring material 208 is a layer of clay that is extruded into a thin sheet. A professional pasta maker may be used for the extrusion process. The clay is preferably sulfur free. The sulfur-free modeling clay is extruded at an even thickness and laid into the anterior portion 34 of the mold 30. Various clay thicknesses may be employed, though one preferred thickness is 1/16 of an inch. The clay is smoothed and contoured to create an even surface. The thin layer of clay creates a new, smooth surface inside the anterior cavity 36p. The layer of clay or “coring” material reserves a space that can later be used for a transparent layer 130.
Returning to
Next, the sclera portion 110 of the ocular prosthesis 100 is formed. This is done by filling the mold 30 with a white-tinted silicone preparation. This is demonstrated by step 230 of
The white-tinted silicone preparation is preferably a custom-blended, medical grade, silicone material. The silicone material is used to form the body or sclera of the prosthesis 100, and may be referred to herein as “Sclera Silicone”. Originally, the Sclera Silicone is a translucent platinum material. However, it is tinted white using silicone pigments suspended in a silicone oil. A catalyst is preferably added to enable curing. The silicone oil may be, for example, a 50-centistoke to a 1,000-centistoke oil. The silicone material forming the Sclera Silicon may be specially ordered from a supplier, or may be mixed by the ocularist in the lab.
The durometer or firmness of the white-tinted silicone preparation can be adjusted with the addition of silicone diluent. Silicone diluent is a silicone oil that occupies space between the silicone molecules, extending the polymer chain and softening the final product.
The Sclera Silicone is optionally placed in a vacuum to remove any air bubbles. The white-tinted silicone material is then poured into the posterior portion 32 of the mold 30. A small amount of Sclera Silicone may also be placed in the anterior portion 34 of the mold 30 against the modeling clay 308. The mold 30 is then clamped together. The white-tinted silicone preparation, or Sclera Silicone, fills the recess 36. However, the white-tinted silicone preparation does not completely fill the recess 36 due to the presence of the coring material 308 along the surface of the anterior portion 34 of the mold 30.
The white-tinted silicone preparation is held in the mold 30 for a period of time. This allows the silicone preparation to cure to form the sclera portion 110. Box 240 of
After the white-tinted silicone preparation has cured, the posterior portion 32 of the mold 30 is removed from the anterior portion 34. This exposes the newly cured sclera portion 110. The sclera portion 110 may then be removed from the mold 30.
After a suitable period of curing, the clamp is released and the mold 30 is pried open. The cured Sclera Silicone casting is removed from the mold 30, and is then cleaned with a solvent. The solvent helps to ensure bonding of a clear layer of silicone to be applied later. The cured Sclera Silicone forms the sclera portion 110 for the prosthetic 100. The sclera portion 110 may also be trimmed and otherwise prepped for painting.
A next step in the method 200, in one embodiment, is the placement of the iris portion 120 and pupil portion 122 on the sclera portion 110. This is represented at box 250 of
When a silicone based ink is used, it is preferably set or semi-cured instantly with a thin layer of catalyst solution for curing the silicone paint. In a more preferred method, the sclera portion 110 or the iris portion 120 or both are painted multiple times for vivid details and effects, and each time the painting is semi-cured before a subsequent painting. Semi-curing before the next painting step allows the addition of more details without disturbing the painted details underneath. Other techniques, such as using cotton or silk fibers to add the effects of blood veins found in the natural eye, may also be used.
As noted, the iris portion 120 further comprises a centrally-located pupil portion 122. The pupil portion 122 may be formed by creating a cylindrical depression within an annular region of the iris portion 120. This may be done, for example, by using a biopsy punch (not shown) that corresponds in size to the patient's natural pupil. Disposable biopsy punches are available in different diameters, and may be used to punch out the pupil portion 122 at the center of the preserved circular annulus in the iris portion 120. The depression is then filled with a black-tinted silicone paint to create the pupil portion 122. This is preferably accomplished by using a fine brush. Once the depression is filled with the black-tinted silicone, the pupil portion 122 may be set with a platinum spray.
The placement of the iris portion 120 and the pupil portion 122 may alternatively include the use of digital photography and printing to form an iris that matches the “natural” eye of the patient. In this respect, the ocularist will use a software program such as Adobe Photoshop to create the iris and to otherwise form a digitally painted disk. This enables the ocularist to manipulate colors and details so as to accurately match the patient's natural eye. The digital file may be saved for future use or modification. This enables the ocularist to generate multiple iris disks with very little effort, and to further create a library of disks.
In this alternative digital embodiment, the iris portion 120 is created by printing a digital image in the shape of a disk and in the appearance of a natural iris. The iris disk is printed onto a durable substrate such as photo paper. The paper is sprayed with a fixative to prevent any smudging or change in color during fabrication of the prosthetic 100. The iris disk is cut out using either a punch or small scissors. The disk is then compared to the patient's natural eye for approval by the patient. Any necessary adjustments in size or color can be accomplished by manipulating the file on computer and reprinting the disk. The substrate with the approved disk is then adhered to the silicone sclera portion 110. The final printed iris disk may be secured to the sclera portion 110 with a small drop of one component silicone medical adhesive.
Next, the thin layer of clay 208 is removed from the anterior portion 34 of the mold 30. This step is shown at box 260 of
The next step is the formation of the transparent layer 130. This is represented by box 270 of
It is noted that the compositional difference between the Sclera Silicone and the Optical Silicone is clarity, strength, and durometer (firmness). The “Sclera Silicone” is translucent, not optically clear, and is firmer and more viscous than the Optical Silicone.
The “Optical Silicone” is preferably poured into the anterior side 34 of the mold 30, then the posterior side 32. The prosthesis 100 with painted sclera 110 and iris 120 portions is carefully submerged into the “Optical Silicone” and clamped in place. The mold 30 is then heat cured for about 5 to 50 minutes in an oven set at 150 to 175 degrees Fahrenheit. The curing step is shown at box 280 of
After curing, the mold 30 is opened and the prosthesis 100 is removed. The prosthesis 100 now comprises the sclera portion 110, the iris portion 120, and the transparent layer 130. The transparent layer 130 allows the color patterns of the ocular prosthesis 100 to be under the protection of a transparent silicone coating. This helps protects the painted iris portion 120 and prevent the colors from fading or changing. This, in turn, allows the ocular prosthesis 100 to be more stable, and longer lasting.
The prosthesis 100 may be trimmed and buffed using an electric hand tool with special disks designed for contouring silicone. At this point, the transparent layer 130 of the ocular prosthesis 100 does not necessarily have a shiny or glossy finish. Therefore, it is preferred that a polish coat be applied to the exterior of the transparent layer 130 in order to create a glossy and transparent appearance. This step is shown at box 290 of
Of interest, the method 200 of the present invention primarily employs an additive polishing technique. The unpolished prosthesis 100 is pushed onto a custom pin rig that impales the prosthesis 100 on a posterior side, providing a stable support with complete access to all surfaces of the silicone prosthesis 100. A small batch of catalyzed “Optical Silicone” with a platinum chemical additive is mixed creating the “Polish Coat.” This “Polish Coat” is applied sparingly to the outer surface (or transparent layer 130) of the prosthesis 100 until the prosthesis 100 resembles clear glass. The prosthesis 100 is allowed to air cure for about a half an hour to an hour, and is then heat cured for an additional hour in an oven set at 150 degrees Fahrenheit. Once cured, the silicone prosthesis 100 is complete and ready to be inserted into the patient's socket 62.
In some instances, a patient may already be in possession of a pre-fitted ocular prosthetic. The ocularist may choose to use the existing prosthetic to form the mold 30, rather than creating a new master. Thus, the present methods accommodate the use of an existing prosthetic. After the new mold 30 is formed, the steps outlined above may be employed for forming the silicone-based prosthetic 100.
The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed broadly to include all variations falling within the scope of the appended claims and equivalents thereof. Furthermore, the teachings and disclosures of all references cited herein are expressly incorporated in their entireties by reference.
This application claims the benefit of U.S. Provisional Patent Application No. 60/822,447, filed Aug. 15, 2006. That application is entitled “Silicone Based Ocular Prosthesis and Method for Making the Same.” The provisional application is incorporated herein in its entirety by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60822447 | Aug 2006 | US |
