An eye for an eye.

Anophthalmia can be congenital or acquired. Malignancy, infection, and trauma may lead to the removal of the eye by enucleation or evisceration. In addition, there are clinical situations where the eye may be blind, shrunken and deformed (phthisis bulbi). Irrespective of the etiology, the loss of an eye can have a profound physical, social, and psychological impact on an individual. The challenge in such situations lies in providing a life-like ocular prosthesis to restore the esthetics, and consequently help provide social rehabilitation.

The ocular prosthesis can be ready-made (stock eye) or custom-made. Stock eyes are supplied in three basic shapes: Oval, standard and three-cornered. Each shape has three sizes: Small, medium and large, and laterality-right and left. The iris is produced in three basic colors: Brown, hazel and blue with some overlap, and the scleral colors are also varied. One basic size of the iris (11.5 mm) is used, and it has a pupil opening of 3.5 mm.[1] Cost and convenience are the major considerations in providing a stock eye, and a skilled ocularist is not necessary.

Custom-made prosthesis has the advantages of the better fit over the socket surface, stability, reduced incidence of discharge and socket infection, comfort, color match, and optimal upper and lower eyelid position and contour.[234] In addition, it needs to be sparingly removed, only once every 3-4 weeks, to clean. It is known that the incidence of socket contraction is significantly low with a custom prosthesis as compared to a stock eye.

Numerous techniques for processing a custom ocular prosthesis exist. Mathews et al.[45] have classified ocular impression and fitting techniques as follows:

Direct Impression

An impression material is injected directly into the enucleated socket. Using the impression, a wax trial ocular prosthesis is made. It is fit, contour, and comfort are assessed. Then it is processed as done routinely.

Impression with Stock Ocular Tray

A stock ocular tray is placed in the socket. This tray has a hollow stem fastened in the middle through which an impression material is injected. Perforations in the tray aid flow and retention of the impression material. Subsequently, the impression is removed, and the wax pattern is fabricated. This wax trial prosthesis is placed in the socket, fitted, and modified as needed. It is then processed.

Impression with Modified Stock Ocular Tray

Exactly, the same as in type 2, but using a modified ocular tray.

Impression with Custom Ocular Tray

This technique involves attaching a suction rod to the patient's existing artificial eye or the custom conformer and investing it in an alginate mould. After the alginate sets, the prosthesis or conformer is removed and replaced with clear acrylic resin, which is then used as the “custom ocular tray.”

Impression using Stock Ocular Prosthesis

This method uses a stock ocular prosthesis as a tray to carry the impression material. An aesthetic stock eye is selected, and its peripheral and posterior aspects are ground to size. The stock eye is then lined with an impression material and inserted for the definitive impression. Alternately, the impression material can be injected directly into the socket and then reinforced by placement of the stock eye. The resulting impression is processed, providing a customized stock prosthesis.

Stock Prosthesis Modification

This technique involves fitting of a stock prosthesis by trimming and polishing.

Wax Scleral Blank Technique

An empirically manufactured wax scleral blank is tried in the given socket and suitably modified. After the addition of an iris button, it is further processed.

The major considerations in using a specific technique include patient's exacting requirements, time at disposal, cost involved, and the training level of the ocularist/technician. Obtaining impression with a stock or a modified impression tray, and incorporating a matching custom-painted iris button provides the most acceptable cosmesis, and a durable and a comfortable prosthesis [Figures 1 and 2]. A trained ocularist can fabricate 3-4 such prosthesis in a day, making it time- and cost-effective. We have been using this technique routinely in our clinical practice.

Figure 1

Anophthamic left socket in a 4-year-old child following enucleation (for retinoblastoma) by the myoconjunctival technique with a primary orbital implant (a), appears cosmetically optimal following a custom ocular prosthesis (b)

Figure 2

Anophthamic left socket in a 60-year-old lady following enucleation (for malignant melanoma) by the myoconjunctival technique with a primary orbital implant (a), a custom ocular prosthesis (b) that exactly matches with her right eye

The steps in fabricating a custom ocular prosthesis comprise of the following:[4]

Detailed evaluation of the socket by the oculoplasty surgeon to determine if the healing is complete and the socket is ready for prosthesis. In patients with contracted socket, the surgeon may want to deepen the fornices, increase the surface or build in the volume by simple surgical procedures prior to prosthesis fitting to optimize the ultimate cosmesis. Specific requirements if any (ptosis shelf, light-weight prosthesis, self-lubricating prosthesis) are discussed by the surgeon with the ocularist

Examination by the ocularist to determine the type of prosthesis and the nature of customization

Obtaining a socket impression using an appropriate sized ocular tray, generally matching with the size of the existing conformer that the surgeon had provided at the conclusion of the surgery

Preparation of the wax model for the socket

Careful centration of the prosthesis using interpupillary distance, Hirschberg's test, and an iris corneal button and fabrication of iris and pupil to match the fellow eye

This is followed by moulding in acrylic, tinting to match the scleral shade, incorporation of blood vessels, packing with the clear acrylic and final polishing

The final fit is assessed based on the following criteria-comfort, stability, three-planar position-vertical, horizontal, and frontal, eyelid position and contour, lagophthalmos, degree of prosthesis motility, iris color, iris position, horizontal visible iris diameter, pupil size, and scleral color and vascular pattern

Instructions on socket hygiene, prosthesis care, technique of prosthesis removal and insertion, and use of protective glasses.

In this issue of the Journal, Sonune et al. reported excellent outcome in a patient where they used a simplified technique of integration of the socket impression to the back surface of a stock eye that had been selected by the ophthalmologist to match with the contralateral eye.[6] The technique used by the authors is convenient and cost-effective, but the main disadvantage is the inability to exactly match the iris color and limited variations in iris size, which may render several patients unsuitable for this technique.[7]

Fabrication of a custom ocular prosthesis using socket impression and customized iris button remains the gold standard in optimally rehabilitating an anophthalmic socket in a clinical facility where an oculoplasty surgeon works as a cohesive team with a dedicated ocularist. However, improvisations such as that used by Sonune et al. may indeed benefit a certain cross-section of patients where the major consideration may be cost and convenience, and the service is provided by someone who makes an ocular prosthesis only occasionally.