Custom-made ocular prosthesis

Abstract

An ocular defect may affect a patient psychologically. An ocular prosthesis is given to uplift the patient psychologically and improve the confidence. Ocular prosthesis can be custom made or a stock shell. To improve the comfort and matching of the prosthesis with that of the adjacent natural eye an custom made ocular prosthesis is preferred. Different techniques are available to fabricate a custom ocular prosthesis, here we have used paper iris disk technique.

An ocular prosthesis is an artificial substitute for an enucleated eye ball. A prosthesis which adapts well improves the psychological state of the patient and also increases the patient's confidence level and the esthetic value.[1] An ocular prosthesis may be available readymade (stock ocular prosthesis) or can be custom made.[1] A stock ocular prosthesis can be given for a patient when time limitation exists and the cost factor is taken into consideration.[2] But many disadvantages exist in a stock ocular prosthesis, such as ill-fitting, improper shade matching, and so on, whereas a custom-made ocular prosthesis increases the adaptiveness, movement of the eye ball, and exactly matches the iris position as that of the adjacent natural eye.[3,4]

Case Report

A male patient aged 38 years came with the chief complaint of ill-fitting artificial left eye [Figure 1]. He had a history of trauma at the age of 25, and the eye was enucleated and a stock prosthesis was given. On examination, the tissue bed was irritated due to ill-fitting prosthesis. So, the patient was advised to discontinue wearing of the prosthesis. After a week, the patient was evaluated for the relationship of palpebral fissure in an open and closed condition, the muscle control of the palpebrae, and the internal anatomy of the socket in resting and in full excursion. There was adequate depth between the fornices, which could be utilized for better retention of the prosthesis. So, it was decided to replace the missing eye with a custom-made ocular prosthesis.

Figure 1.

Pre- and postoperative

Procedure

An ophthalmic topical anesthesia was given to increase the comfort of the patient while making the impression. External tray technique[5] was used with addition silicon putty and light body wash impression for making the impression of the socket [Figure 2]. The impression was removed after it was set and it was boxed and poured with dental stone up to the height of contour. After the stone was set, separating media was applied and the remaining impression was poured [Figure 3].

Figure 2.

Ocular impression made

Figure 3.

Double layer cast

The cast was retrieved from the impression and prepared for wax pattern fabrication by coating a layer of separating media on to the defective surface before the molten wax was poured. Once the wax was solidified, the upper half of the cast was sectioned along the medial and lateral canthus [Figure 4]. The wax pattern was retrieved by fracturing along the sectioning and wax pattern was smoothened to remove any sharp ridges and undesirable irregularities and then polished.

Figure 4.

Retrieval of wax pattern

The fit of the pattern was checked in the patient by observing the extension of the wax pattern into the fornices [Figure 5]. The areas of over extensions were adjusted by trimming the wax. The contour and support of the eye lid with the pattern was checked while the eye was in open and closed positions. After checking the fit, contour, and support of the pattern, it was flasked and processed with scleral resin. After deflasking, the scleral blank was polished using pumice [Figure 6].

Figure 5.

Wax pattern try in

Figure 6.

Processed sclera

The finished scleral blank was tried in the patient and middle of the pupil was marked when the patient gazed straight. The size of the iris of the adjacent eye was measured and transferred on to the scleral blank and once again verified. The blank was reinvested to allow final processing of prosthesis after coloring and the location of iris was also transferred to the investment and a scrapper was used to create corneal prominence in the investment. After the investment was set, the scleral blank was retrieved from the flask for corneal painting.

Corneal painting was done on a disk of ordinary artist's water color paper which was cut 1 mm short to the size of iris[6] (as the corneal prominence will cause slight magnification of iris disk). Using a thin brush and artist acrylic paint, many strokes from the center of the iris to the periphery were painted to match the color of natural iris. Coloring was done in layers: 1^st layer, background color; 2^nd layer, color around the pupil; and 3^rd layer, an additional lighter striation was applied to give the painting a 3D effect. A black spot was painted in the center of the disk to represent the pupil. Disk of painting was dried and compared for color matching.

An abrasive stone was used to reduce 1 mm of the anterior surface of the scleral blank over which the iris painting was placed and tried in the patient for orientation. After satisfactory orientation was achieved, the blank was removed from the socket and fine red threads were placed on the scleral portion to mimic the blood vessels. The entire scleral portion was coated with a thin layer of clear acrylic syrup to keep the blood vessel fibers and the painting in place.

Once it was set, the scleral blank was replaced on to the flask and the processing was done with clear acrylic. After the processing was completed, it was polished using pumice [Figure 7].

Figure 7.

Iris painting on processed sclera

Prior to insertion of the finished prosthesis, it was disinfected using 70% isopropyl alcohol and 0.5% chlorhexidine solution. After thoroughly cleaning the prosthesis with saline solution to prevent chemical irritation, it was inserted and checked for fit, contour, and movements.

Discussion

The custom-made ocular prosthesis conforms accurately to the socket as the prosthesis fabrication is based on the existing anatomy of the patient, thus giving benefits of increased adaptation, movement of the eye ball, and the exact match of the iris position as that of the adjacent natural eye.[1]

According to Beumer et al.,[7] intimate contact between the ocular prosthesis and the tissue bed is needed to distribute even pressure, so a prefabricated prosthesis should be avoided. Moreover, the voids in the prefabricated prosthesis collect mucus and debris, which can irritate mucosa and act as a potential source of infection, which are minimized in custom-made prosthesis.[1,8]

Conclusion

A technique for fabrication of a custom-made ocular prosthesis has been described. This technique also permits the finished prosthesis to generate an equal distribution of pressure and intimate adaptation to the tissue bed. A properly fabricated custom-made prosthesis enhances the patient's comfort and confidence by increased adaptiveness and natural appearance, and also maintains its orientation when the patient performs various eye movements. The optimum cosmetic and functional results of a custom-made ocular prosthesis enhance the patient's rehabilitation to a normal lifestyle.