Magnetic ocular prosthesis for shallow contracted socket.

Contracted sockets with poor retention of ocular prosthesis are difficult to manage especially when it is a dry socket. A 50-year-old lady with history of irradiation to the socket following enucleation for retinoblastoma reported to us with severe socket contracture, dry socket, and inadequate lid closure with a poorly retained ocular prosthesis. She was using a stone in the socket for support with a cracked stock ocular prosthesis placed over it. A two-piece ocular prosthesis was created with a base and shell with neodymium-boron-ferrous magnets in each part, with good retention and positioning, and this was cosmetically acceptable to the patient. To the best of our knowledge, this is the first report of such a two-piece magnetic ocular prosthesis.

Loss of an eye leads to loss of binocular vision, loss of depth perception, affects the social life adversely, and negatively impacts one's professional life. Contracted sockets are difficult to manage more so when they are dry. Surgery by mucus membrane or dermis fat grafts is more likely to fail in these cases. We report the fabrication of a two-piece magnetic ocular prosthesis in a 40-year-old lady banker with severe socket contracture with a previous history of enucleation for retinoblastoma in childhood followed by irradiation. We created two units, a base and a customized shell on top, both having magnets ensuring good stability and cosmetically acceptable appearance. While a two-piece magnetic orbito-facial prosthesis has been reported before,[1] to the best of our knowledge, this is the first report of a two-piece magnetic ocular prosthesis.

Case Report

A 50-year-old lady banker presented to our oculoplasty service with a poorly retained ocular prosthesis. She gave a history of enucleation followed by radiation to her right socket. She had consulted at many clinics to get a suitable ocular prosthesis. On examination, her left eye was within normal limits. Her right eye socket examination revealed she was using a stone as a base in the eye over which she was using a cracked and damaged stock prosthesis [Fig. 1a and b]. The socket was bone dry with a large volume deficit and the lids were contracted. Her inferior fornix was shallow and there was inadequate closure of both the upper and lower lids [Fig. 2]. She was experiencing severe discomfort due to the weight of the stone and the prosthesis would fall out when she bent down. Because surgery in the form of mucus or dermis fat grafts may be unsuccessful due to poor vascularity of the socket, a decision on fabricating a custom ocular prosthesis was made. She was referred to our ocularistry service.

Figure 1

(a) Right eye socket examination revealing she was using an ill-fitting prosthesis. (b) She was using a stone as a base in the eye over which she was using a cracked and damaged stock prosthesis

Figure 2

The socket was bone dry with a large volume deficit and the lids were contracted. Her inferior fornix was shallow and there was inadequate closure of both upper and lower lids

For the prosthesis to have a good position and avoid a sunken look, a base was created over which a customized shell was placed. An alginate impression was made, and this was transformed into a wax prototype. The wax prototype was tried in the patient's eye to obtain an optimal fit. The corneal button position was made central to avoid any appearance of squint in the primary position. On the wax model, the size of the base piece was adjusted, until the prosthetic eye placed over the base was as anterior in position as the left eye normal cornea [Fig. 3a]. Neodymium-boron-ferrous magnets (Dyna Dental, The Netherlands) were incorporated in the clear polymethylmethacrylate (PMMA) base model and in the ocular prosthesis [Fig. 3b]. The ocular prosthesis made of white PMMA had a corneal button which was hand-painted using water-resistant pigments, and lamination by clear PMMA was performed over it to match the color and appearance of the normal left eye. To mask the shortening of the lids, the ocular prosthesis was painted superiorly and inferiorly dark brown to match the color of the lids. The overall result with the two-piece prosthesis was an acceptable fit and near similar match to the left normal eye [Fig. 4a and b].

Figure 3

(a) Creation of an alginate impression of the base and ocular prosthesis. (b) The base seen on the left is made of clear PMMA with neodymium-boron-ferrous magnet (Dyna Dental, The Netherlands) in the center and on the right is the custom ocular prosthesis made with white PMMA with Ne-Bo-Fe magnet in the center of the back surface

Figure 4

(a) The overall result with the two-piece prosthesis was an acceptable fit and near similar match to the left normal eye. (b) The ocular prosthesis made of white PMMA had a corneal button which was hand-painted using water-resistant pigments and color matched to the normal left eye with lamination by clear PMMA over it. To mask the shortening of the lids, the ocular prosthesis was painted superiorly and inferiorly dark brown to match the color of the lids

Discussion

Any facial deformity is a severe debilitating factor for the psychology of any individual. Management of dry contracted sockets is always a challenge. Due to poor vascularity, grafts and surgeries fail. Prosthesis is noninvasive and hence is always preferred. While fabricating an orbital prosthesis, various techniques have been used including magnetic prosthesis and the use of obturators to restore speech and deglutition.[23] Osseointegrated implants provide the most reliable prosthesis retention; however, additional surgery which could be expensive is needed with a prolongation of the period until rehabilitation with prosthesis.[45] Adhesives can be used to retain prosthesis – these are readily available, easily applied, and provide satisfactory retention for a limited period of time.[1] However, after prolonged use, they can cause irritation, allergy, or can simply lose their adhesive power. When fabricating an orbital prosthesis, undercuts are used to stabilize the prosthesis. Vasisht et al. described a two-piece orbital prosthesis where they used samarium–cobalt magnets which they fabricated into an acrylic pillar and mechanical retention was achieved using undercuts and magnets.[1]

Conventionally retained ocular prostheses are practical, trouble free, cost-effective, and successful. Conventional magnets have low break-away force, are not strong, can break in long run, are biodegradable, and lose their magnetic power in long run. Neodymium-boron-ferrous magnets, on the other hand, are alloy magnets with increased strength and increased coercivity (resistant to demagnetization).[4] In addition, they are open-field magnets which do not need close contact.[4] These magnets are the choice when fixing individual fabricated tooth in patients with loss of teeth. Hence, we chose Ne-Bo-Fe magnet. A base was needed in our case to create a stable foundation, to share the weight, and to enhance the volume to fit an ocular prosthesis over it. It helped in ensuring that the ocular shell on top did not have a sunken appearance. A good color match of the sclera and the cornea was achieved; in addition, we painted the superior and inferior borders dark brown to give it the appearance of lids; this was to mask the prominent eye look due to the retracted upper and lower lids. Magnets are incorporated in both the parts for accurate alignment and weight division. The final prosthesis fit snugly in the socket and gave a normal appearance to the patient. We describe a new technique of fabricating a magnetic two-piece ocular prosthesis which to the best of our knowledge has not been reported in literature yet.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.