A Novel Technique for Characterization of Ocular Prosthesis by Utilizing Ceramic Stains and Composite Glaze

Introduction

Characterization of a custom ocular prosthesis is a critical step in providing life-like effect to the prosthesis. It can boost the psyche of the patient significantly. Various techniques in the past have been advocated to make the prosthesis look as natural as possible. The most commonly documented technique for scleral characterization includes painting the scleral blank with acrylic or oil paints, followed by sprinkling pink acrylic fibres to mimic vascularization of the eye.^1,2 Alternatively, silk threads or simply red color paint have also been used.^2,3 Once the paint is dried, fibres are then secured in place with monopoly syrup after which the mould is scraped, packed and heat polymerized with clear acrylic to add a ‘depth effect’ to the prosthesis.¹ Chamaria et al., used a protective layer of G-Coat PLUS (GC Corporation) to fix a printed cutout of the iris and sclera of the normal eye followed by packing a clear layer of heat cure acrylic resin.⁴

This article describes a simple technique for characterization of ocular prosthesis by utilizing ceramic stains (VITA Azkent Plus, VITA Zahnfabrik), silk threads, universal adhesive (composite bonding agent), and external glaze (Optiglaze Color- clear HV).

Case Presentation

A thirty-two year old female patient reported to the Department of Prosthodontics and Crown and Bridge

for replacement of an existing artificial eye due to its unaesthetic appearance. Patient was a diagnosed case of orbital embryonal rhabdomyosarcoma and lost her left eye at the age of ten years. Ocular prosthesis was fabricated using conventional steps till iris centering and processing in heat cure acrylic resin. A novel technique was devised for characterization, the procedure of which is described below.

1. The heat cure acrylic scleral blank was grossly finished before beginning the characterization (Figure 1).
2. High-quality photographs of the patient were taken in natural daylight for reference. 
3. Ceramic stains (VITA Azkent Plus, VITA Zahnfabrik) were mixed with universal dental adhesive (Te-Econom Bond, Ivoclar AG) to match the shade of sclera of the patient (Figure 2).
4. A small brush was used to paint the scleral blank to the desired shade.
5. The conjunctival vascular patterns were reproduced by placing red silk threads on the coloured blank. If there was any pigmentation, brown stain can be used.
6. The prosthesis was light-cured for three minutes in the photopolymerization unit (Sibari SR620-Sirio dental).
7. Two uniform coats of external glaze (Optiglaze Color-clear HV) were applied with clean brush and light-cured for three minutes in photopolymerization unit (Figure 3).
8. The prosthesis was examined for any nodules or sharp ends or surface irregularities before insertion (Figure 4).

Discussion

Custom ocular prosthesis has better contour and fit on the tissue bed and thus it is possible to achieve the eye movements and color matching close to the contralateral natural eye. The success of ocular prosthesis depends upon the extent to which the prosthesis resembles the natural eye and this can be achieved by various methods of characterization as described in the literature.

The steps in fabrication of customized ocular prosthesis includes impression of socket, wax pattern trial, iris positioning, acrylization, characterization and final clear acrylic layer acrylization. In conventional method, a layer of acrylic is trimmed off, after which the staining is done and threads are added for vascular effect. Following this, clear heat cure acrylic is packed into the mould. The final curing may compromise the esthetics due to porosities, displacement of threads or can have diffuse appearance of characterization. The thickness of superficial clear acrylic layer may lead to increased or decreased amounts of magnification of the iris, which may in turn lead to unaesthetic outcomes.

The present technique opens the window to faster and yet stable outcome of characterization and can be routinely used in a clinical setup. It helps to secure the stains and threads more predictably than the conventional technique where the prosthesis is re-introduced to high temperature and pressure for curing of clear acrylic layer. This novel technique effectively controls the thickness and esthetic outcome of the prosthesis by using ceramic stains which can be just painted on and then secured using an external glaze. The technique has its merit in being simple and time saving with predictable results.

Conclusion

This article proposes a streamlined method for ocular prosthesis characterization. By circumventing traditional curing of acrylic, this technique ensures a natural appearance with minimal risk of thread displacement, porosity and irregularities. Overall, it represents a significant advancement in restoring both physical appearance and psychological well-being for patients, fostering improved satisfaction and quality of life.

Conflict of Interest

Nil