Custom ocular prosthesis: a palliative approach.

The goal of palliative care is the achievement of the best quality of life for patients and their families. Eyes are generally the first features of the face to be noticed. Loss of an eye is a traumatic event which has a crippling effect on the psychology of the patient. Several ocular and orbital disorders require surgical intervention that may result in ocular defects. An ocular prosthesis is fabricated to restore the structure, function, and cosmetics of the defects created by such conditions. Although an implant eye prosthesis has a superior outcome, due to economic factors it may not be a feasible option for all patients. Therefore, a custom-made ocular prosthesis is a good alternative. This case report presents a palliative treatment for a patient with an enucleated eye by fabricating a custom ocular prosthesis which improved his psychological, physical, social, functional, emotional and spiritual needs.

INTRODUCTION

Physical abnormalities or defects that compromise appearance and function are sufficient to render an individual incapable of leading a relatively normal life. Eye is a vital organ not only in terms of vision but also being an important component of the facial expression. Removal of this organ may be indicated in cases of a severe trauma; congenital abnormality; or disease such as an infection, a tumor or untreatable painful glaucoma either by enucleation, evisceration, or exenteration.[12]

Frequently, an implant is placed in the tissue bed to facilitate the construction of an ocular prosthesis. The purpose of ocular implants is to replace the lost tissue volume and improve prosthesis mobility. There are three basic types: Buried, semiburied; integrated, buried;semi-integrated. Buried; semi-integrated implants are the most common method of replacing the volume loss in the socket following enucleation or evisceration. Modern ocular implants are available in various materials like metal, silicone, hydroxyapatite, or acrylic resin. However, the principal complication associated with ocular implants is the erosion of the overlying tissue, resulting in the exposure of the implant or contamination of the implants at the time of insertion.[3]

A definitive technique for fabricating artificial eyes using acrylic resin was developed by the United States Naval Dental and Medical Schools and was published in 1944. Unlike glass eyes which were earlier used, the acrylic resin eyes were solid. The material was lightweight, easy to fit and adjust, unbreakable, translucent, easily fabricated, had intrinsic and extrinsic coloring capabilities, and was inert to the socket secretions.[4-6]

An ocular prosthesis can be either readymade (stock) or custom-made. Stock prosthesis comes in standard sizes, shapes, and colors. They can be used for interim or postoperative purposes.[17-9] Custom eyes have several advantages including better mobility, even distribution of pressure due to equal movement thereby reducing the incidence of ulceration, improved fit, comfort, and adaptation, improved facial contours, and enhanced esthetics gained from the control over the size of the iris, pupil, and color of the iris and sclera.[3510]

CASE REPORT

A 58-year-old male patient reported to Department of Prosthodontics for the fabrication of a fixed partial denture for the replacement of missing teeth. Examination and history revealed that the patient had suffered from chemical burn (ammonia gas) in his left eye. Following trauma, an enucleation was done. After 5 months of surgical intervention, a stock prosthesis was given to the patient. However, the patient was dissatisfied with the esthetics and the fit of the prosthesis. The patient was given an option of an implant-retained ocular prosthesis but the patient was not ready to take up the surgery purely due to economic reasons. So it was decided that a custom-made ocular prosthesis which would enhance esthetic and functional results would be the best to meet the needs of the patient.

Patient evaluation

The patient was using the stock prosthesis since 2 years. Examination of the socket revealed that the healing was complete and there was no inflammation [Figures 1 and 2].

Figure 1

Preoperative view

Figure 2

Examination of the enucleated socket

Following observations were made during examination:

Relationship of the palpebral fissures in an open and closed position.

Evaluation of the muscular control of the palpebrae.

Internal anatomy of the socket in a resting position and during full excursive movements of the eye musculature.

Mobility of the posterior wall of the defect during the movement of the intact eye.

Fabrication of the ocular prosthesis

Treatment was planned after careful examination of the area of defect. The patient was explained about the procedure and its limitations.

Impression[31112]

An impression of the socket was made with irreversible hydrocolloid impression material (Jeltrate Dustless alginate; Dentsply International, York, PA, USA). An impression tray was fabricated from the hard baseplate wax (TruWax Baseplate wax, Extra Hard, Trubyte; Dentsply International) by warming it over a flame and adapting it to the contour of the area around the eye. The approximate pupil location on the wax tray was perforated to a 3- to 4-mm diameter hole. Multiple perforations were made over the remainder of the surface. The injection tube was fabricated from the tip of a 5-ml plastic syringe (Unolok; Hindustan Syringes and Medical Devices Ltd., Faridabad, Haryana, India) and cut at approximately 7 mm from the end. Sides of the tip were roughened and wedged into the pupil perforation hole. The irreversible hydrocolloid was mixed with enough water so that it flowed easily. The mixed material was placed in a large syringe (20 ml, Dispovan R; Hindustan Syringes and Medical Devices Ltd.) and injected into the socket through the injection tube [Figure 3].

Figure 3

Impression of the socket made with irreversible hydrocolloid

Patient position

The patient was seated erect, requested to stare at a distant spot, and instructed to hold his gaze in a straightforward position with eyes open while the impression was being made. This procedure ensures that the posterior aspect of the enucleated socket and its rectus muscles are in the same relative position as those of the remaining eye.

Pouring of the cast

After the material was set, it was carefully removed from the socket. The impression was checked to ensure that all the surfaces were recorded. A two-piece Type III dental stone cast (Kalabhai Dental, India) was poured to immerse the lower part of the impression. After the stone had set, the separating medium was applied on the surface. A second layer was then poured. Markings were made on all four sides of the cast for proper reorientation [Figure 4].

Figure 4

Two-piece dental cast

Fabrication and fitting of the sclera wax pattern

The wax pattern was fabricated by pouring the molten wax into the cast. The wax was properly contoured and carved to give it a simulation of the lost eye.

Try-in of the wax pattern was done. The wax pattern was checked for the size, support from tissue, simulation of eye movement, and eyelid coverage [Figure 5].

Figure 5

Try-in of the scleral wax pattern

Position of the iris–lens assembly on the wax scleral pattern

The position of the iris was located with the help of a millimeter grid placed on the patient's face. The patient was instructed to fix the gaze of the natural eye on an object at least 3 ft in front and at eye level.

The position of the iris–pupil area of the natural eye in relation to the inner and outer canthus and upper and lower lids was marked on the grid. The same markings were transferred on the defect side [Figure 6].

Figure 6

Location of the iris

Iris disc painting[3613–15]

A prefabricated iris button made of clear acrylic resin (DPI heat cure resin; Dental Products of India, Mumbai, Maharashtra, India), of size approximately 0.5 mm smaller than the actual measurement matched, was selected. Iris painting was done with acrylic paints (Fevicryl; Pidilite Industries Ltd., Mumbai, Maharashtra, India) on water color paper discs [Figures 7 and 8]. The colors most often used are titanium white, ultramarine blue, burnt sienna, yellow ochre, cadmium yellow, and alizarin crimson. The paints are mixed with water to a heavy consistency. The brush point should be very fine so that delicate striations can be produced. The hue should be slightly more intense than that of the natural eye because the color of the iris painting loses value or darkness during processing. There are five basic parts to an iris painting: The pupil, the background (limbus), the collarette, the stroma, and the individual markings or striations. The pupil is painted first and is located in the center of the iris disk.

Figure 7

Iris button

Figure 8

Iris disc painting

The coloring in the area of the limbus is the deepest found in the normal eye. It is found on the outside perimeter of the iris. This color is the key for blending of the paints for subsequent procedures. This coat is applied in a heavy layer using brush strokes from the center toward the periphery.

The second zone of color occupies about one-half the radius of the disc and is found just within the zone of the background color. It is referred to as stroma color because its structure is radiating and striated in nature. The stroma is lighter in color and can usually be matched by the simple addition of titanium white to the background color.

The third zone of color is the collarette color, a name suggesting a collar around the papillary aperture. It is found within the stroma color and can be matched with the addition of brown to the stroma color.

The fourth zone comprises the markings and assumes a variety of color shades ranging from lemon-yellow to brown.

The color was checked periodically by applying a droplet of distilled water to the center of the disc and seating the lens over the disc. The water interface allows the assembly to be viewed as it will appear after the lens and disc are permanently fused. The iris button was positioned on the iris painting using a monomer polymer syrup made by combining nine parts of the heat-cured acrylic monomer to one part of clear acrylic polymer by weight. The disc assembly was attached to the wax pattern and evaluated in the patient [Figure 9].

Figure 9

Final try-in with the iris lens assembly in position

Then shade of the sclera portion was selected using the tooth colored acrylic shade guide. Flasking was done taking care that the iris was secured to one counter of the flask and remaining part in the other portion of the flask. Packing was done with the selected heat cure tooth colored acrylic [Figures 10 and 11]. A long curing cycle (9 h at 165°F) was carried out for acrylization. The stalk of the ocular button, flash, and irregularities were removed from the surface. Approximately 1 mm of the anterior scleral curvature of the prosthesis was reduced to allow for sclera characterization and for the application of the clear acrylic resin to regain the contours of the finished prosthesis. Red silk fibers were placed onto the surface of the sclera using the monomer polymer syrup. The pattern and type of vessels (sinuous, tortuous, straight, and branched) of the opposite eye were reproduced [Figure 12]. A thin layer of the modeling wax was then applied on the surface of the characterized eye. This layer was then acrylized using clear heat cure acrylic following previously described time and temperature, to fix the characterizations and to give prosthesis the clear sheen present in natural eyes [Figures 13 and 14]. After the eye was recovered from the flask, flash and irregularities were removed. The prosthesis was finished and polished with the flour of pumice (Whip Mix Corporation, USA).

Figure 10

Flasking of the wax pattern

Figure 11

Dewaxed flask with the iris button in the counter flask

Figure 12

Characterization of the sclera

Figure 13

Thin layer of the base plate wax on the characterized sclera for the application of the clear acrylic resin

Figure 14

Final prosthesis

Patient instructions

The method of insertion and removing the prosthesis and its care were demonstrated to the patient.

The prosthesis should be removed at least once a day for cleaning. Cleaning should be done with a mild soap or detergent to avoid pitting, crazing, or clouding of the prosthesis.

The prosthesis should not be allowed to come into contact with alcohol or solvents of any kind as this could cause crazing of acrylic resin.

Should the eye become scratched, it must be returned for polishing.

DISCUSSION

Ocular prosthesis is an artificial replacement of the bulb of the eye. Multidisciplinary management and a team approach are essential in providing accurate and effective rehabilitation and follow-up care for the patient. Therefore, combined efforts of the ophthalmologist, oral and maxillofacial surgeon, plastic surgeon, and the maxillofacial prothodontist are essential to restore the patient's quality of life.

A properly fitted and accepted custom ocular prosthesis has following characteristics:[15]

Retains the shape of the defect socket.

Prevents collapse or loss of the shape of the lids.

Provides proper muscular action of the lids.

Prevents accumulation of fluid in the cavity.

Maintains palpebral opening similar to the natural eye.

Mimics the coloration and properties of the natural eye.

Has gaze similar to the natural eye.

Although the prosthetic rehabilitation may be enhanced with the use of implants, which can coordinate with the movements of the natural eye, they are not always possible or feasible.

The use of custom-made ocular prosthesis has been a boon to the patients who cannot afford the implant placement. Also, as discussed above, the esthetic and functional outcome of the prosthesis was far better than the stock ocular prosthesis [Figures 15–17]. Although the patient cannot see with this prosthesis, it has definitely restored his self-esteem and allowed him to confidently face the world.

Figure 15

Stock ocular prosthesis that was used by the patient

Figure 17

Patient with the custom ocular prosthesis

Patient with the stock ocular prosthesis