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 Table of Contents  
CASE REPORT
Year : 2020  |  Volume : 10  |  Issue : 2  |  Page : 117-121

A novel technique for precise iris positioning while fabrication of custom made ocular prosthesis


Department of Prosthodontics Crown and Bridge, Maulana Azad Institute of Dental Sciences, New Delhi, India

Date of Submission26-Jun-2020
Date of Acceptance12-Oct-2020
Date of Web Publication16-Feb-2021

Correspondence Address:
Dr. Amala Nancy
4/1091-A, MGR Nagar, Melavasthachavadi, Thanjavur - 613 005, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijohs.ijohs_23_20

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  Abstract 


The prosthetic rehabilitation of ocular defects offers psychological benefit to the patients with congenital or acquired defects of eye. The most critical step involved in the construction of ocular prosthesis is its precise iris positioning. This case report introduces a simple novel approach for iris positioning in ocular prosthesis using facebow and in-office materials.

Keywords: Enucleation defect, facebow transfer, grids, iris positioning, ocular prosthesis


How to cite this article:
Nancy A, Satheesh R, Gupta R, Gill S. A novel technique for precise iris positioning while fabrication of custom made ocular prosthesis. Int J Oral Health Sci 2020;10:117-21

How to cite this URL:
Nancy A, Satheesh R, Gupta R, Gill S. A novel technique for precise iris positioning while fabrication of custom made ocular prosthesis. Int J Oral Health Sci [serial online] 2020 [cited 2021 Jun 15];10:117-21. Available from: https://www.ijohsjournal.org/text.asp?2020/10/2/117/309446




  Introduction Top


Ocular defects can be either of congenital or acquired. Acquired defects are due to pathological or traumatic reasons which necessitates the surgical intervention, resulting in the removal of eyeball.[1] Surgical procedures employed in complete or partial removal of eyeball include evisceration, enucleation, and exenteration. Evisceration is the removal of the contents of the eye but leaving the outer layer of the eyeball, or sclera, intact. It is done in the case of infections, severe pain, or problems inside the eye if vision is already lost.

Enucleation involves the removal of the eye, including the globe, but leaving the rest of the orbital (eye socket) contents in place such as bones of the orbit, extraocular muscles, fat, and conjunctiva. Enucleations are indicated for infections or malignant cancers that are completely within the globe of the eye.

Orbital exenteration is the removal of all eye socket contents including muscles, the lacrimal gland system, the optic nerve as well as varying parts of the bone of the orbit. The eyelid can be spared, depending on the extent of the tumor. This is done for large cancers of the eye, the skin over the eye or eyelid, or cancers from other areas that extend into the eye socket including the paranasal sinuses, maxilla, skin, or a part of the eye, or due to nonresponsive infections such as aggressive fungal infections.

Those patients undergo psychological stress due to facial asymmetry and disfigurement, which could be possibly addressed by the maxillofacial prosthodontist.

The prosthetic rehabilitation of postenucleation and evisceration defects is the fabrication of ocular prosthesis, while orbital exenteration necessitates the fabrication of orbital prosthesis.

The ocular prosthesis may be prefabricated or custom made. Although prefabricated are easily available, it has disadvantages such as poor fit, poor esthetics, and poor eye movements. All these can be overcome by customized ocular prosthesis as it records physiologic recording of margins providing more intimate contact with the tissue bed. Hence, the retention is an added advantage for custom-made ocular prosthesis.[2]

An esthetic and comfortable ocular prosthesis alleviates patient's psychological stress and improves the quality of life.[3]

There are various methods such as visual assessment,[4] pupilometer,[5] natural measurements,[6] use of eyewear with graphic grid positioning,[7] and use of facebow with graphic grid method[8] have been proposed and followed.

The present article represents a novel method for precise iris positioning employed in posttraumatic enucleation defect of eye with the use of simple in-office materials in prosthodontist's clinic.


  Case Report Top


A 31-year-old male reported to the Department of Maxillofacial Prosthetics, Maulana Azad Institute of Dental Sciences, New Delhi, India, with the chief complaint of facial disfigurement due to missing left eye. He had a history of traumatic injury followed by enucleation of the left eyeball 4 months ago and was using stock conformer for the past 3 months [Figure 1].
Figure 1: Preoperative anopthalimic socket with conformer

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Diagnostic assessment

Examination of the defect shows properly healed ocular mucosa, and sufficient extension present for retention of the prosthesis. Hence, the prognosis was considered to be fair. The treatment plan for fabrication of custom-made acrylic ocular prosthesis was made, and an informed consent was obtained.

Impression procedures

Impression procedures were carried with the patient in sitting at erect position to allow the tissues to be recorded in the natural drape. The primary impression of the anopthalmic socket was made using irreversible hydrocolloid impression material loaded in a disposable syringe. The diagnostic casts were poured using dental plaster.

The functional impression was made using light body polyvinylsiloxane material loaded in a custom-made self-cure acrylic resin tray. The master cast was made using dental stone with split cast technique.

Wax conformer try-in

The wax conformer was fabricated using ivory wax tried in the patient's eye socket and adjusted for the desired volume, retention, and comfort.

Iris positioning using novel innovative technique

The facebow was used as a reference element as it can be reproduced multiple times. For precise positioning of the pupil, a special assembly made of metal ruler with three wooden toothpicks with the blunt end was used [Figure 2]. For patient's safety, safe distance of 1 inch from the outer eyelid was maintained. The patient was advised to look straight in the upright position; the center of pupil is accurately positioned with the wooden blunt toothpicks at the level of lower eyelid so as to reduce the strain in the patient's eye [Figure 3]. The measured distance from the midline of the ruler is marked, then the positioned is placed at the other side of the ruler accurately mimicking the center of the pupil.
Figure 2: Special assembly made of metal ruler with three wooden toothpicks with blunt ends

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Figure 3: Special assembly in situ

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Two identical graph grid templates along with the wooden stick frames were positioned on to the metallic frame of the facebow [Figure 4]. The outlines of the pupil were marked into the graphic grid [Figure 5]. Transfer of the marked outlines into wax conformerwas done by superimposition .
Figure 4: Graphic grids attached to the facebow

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Figure 5: Transfer of outline of pupil on the wax conformer

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Wax trial

The iris disc stock eye was trimmed and accurately positioned on the cast according to the markings obtained. The wax conformer with the stock iris was tried in.

Shade matching

Shade matching was performed using preprocessed heat cure tooth-colored acrylic resin with A1 shad and was found to be lesser in value in comparison with its natural eye. Hence, clear heat cure acrylic was mixed at two proportions 1:1 and 1:2, and out of these two, the 1:1 final shade was selected [Figure 6].
Figure 6: Shade matching

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Prosthesis fabrication and delivery

The prosthesis was processed with the heat cure acrylic resin in a conventional manner [Figure 7]. The finished prosthesis was delivered to the patient with postinsertional instructions [Figure 8]. The patient was advised to limit the removal of prosthesis once a day for cleaning using soap and water. Recall visits were followed monthly for polishing to prevent the deposition of proteins and bacteria. The patient was satisfied with the prosthesis.
Figure 7: Finished custom-made ocular prosthesis

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Figure 8: Postinsertion frontal view of the patient with the best esthetic match

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  Discussion Top


The fabrication of eyes is not limited to this modern age. They have been used for centuries, with the earliest known examples found in mummies dating back to the fourth dynasty in Egypt (1613–2494 BC).

Ambroise Pare, a French dentist, is considered to be the pioneer of modern artificial eyes. He fabricated eye made of glasses and porcelain.

Naval dental school (1940) tested the use of acrylic resin in fabricating a custom ocular prosthesis. Unlike a glass eye, an acrylic eye was easy to fit and adjust, unbreakable, inert to ocular fluids, esthetical good, longer lasting, and easier to fabricate.

The defects of the eye can be due to congenital malformations, accidental trauma, and or any pathology-related surgical intervention. It can be an ocular defect or orbital defect.[9]

Even with the advent of microvascular surgery and free tissue transfers, surgical reconstruction alone cannot fully restore this area. Prosthetic rehabilitation is needed.

The prosthetic rehabilitation of such defects includes ocular prosthesis or orbital prosthesis. The procedures include the impression of socket, wax pattern trial with iris positioning, and acrylization.

To achieve the best esthetic outcome, iris positioning is a critical step, as it mandates us to maintain the interpupillary distance and to replicate the natural gaze of the contralateral eye.

Subjective methods such as visual assessment are considered arbitrary. Objective methods such as facial measurements and pupilometer have been proposed, yet they have less dimensional accuracy.

Although a method with the use of facebow with graphic grid method for outlining the pupillary diameter has been proposed, the optical gaze was not taken into consideration.

Here, the use of metal ruler with the wooden toothpicks with blunt ends has been proposed to orient the gaze of the vision in addition to graphic grid method, with the use of facebow to achieve a naturally mimicking prosthesis.

This novel method has the following advantages over previous described methods

  1. This is a simple method uses in-office chairside armamentarium and less cost
  2. It uses facebow; hence, reorientation is possible for multiple times with the established reference plane (infraorbital foramen)
  3. There is no need of assistants as the facebow itself can be stabilized with the cotton rolls kept inter occlusally
  4. It utilizes two methods of precise positioning of iris, both center of iris and the periphery are positioned accurately; hence, it replicates the natural eye gaze and pupillary position.



  Conclusion Top


The success of ocular prosthesis mainly depends on the precise positioning of iris disk assembly. This simple technique described here easy to use, more accurate, and allows repeated verification whenever needed with the help of the facebow assembly. This method described here has provided good esthetics mimicking a natural look and high patient satisfaction. Therefore, we recommend this technique for precise iris positioning and to get desired results.

Declaration of patient consent

The authors certify that they have obtained the appropriate consent form. In the form, the patient has given his consent for his images and other relevant clinical information to be reported in the journal.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Beumer III J, Curtis TA, Mark TM. Maxillofacial Rehabilitation: Prosthodontic and Surgical Considerations. 3rd ed.. St Louis: Ishiyaku EuroAmerica. Inc.,; 1996. p. 225-47.  Back to cited text no. 1
    
2.
Taylor TD. Clinical Maxillofacial Prosthesis. 1st ed.. Chicago: Quintessence; 2000. p. 265-7.  Back to cited text no. 2
    
3.
Bartlett SO, Moore DJ. Ocular prosthesis: A physiologic system. J Prosthet Dent 1973;29:450-9.  Back to cited text no. 3
    
4.
Benson P. The fitting and fabrication of a custom resin artificial eye. J Prosthet Dent 1977;38:532-8.  Back to cited text no. 4
    
5.
Roberts AC. An instrument to achieve pupil alignment in eye prosthesis. J Prosthet Dent 1969;22:487-9.  Back to cited text no. 5
    
6.
McArthur DR. Aids for positioning prosthetic eyes in orbital prostheses. J Prosthet Dent 1977;37:320-6.  Back to cited text no. 6
    
7.
Meena AA, Vidya C, Praveen R, Manjita MP. Precise iris positioning in ocular prosthesis using an eyewear. J Dental Sci 2017;2:000121.  Back to cited text no. 7
    
8.
Chamaria A, Aras MA, Chitre V, Costa GCD. Iris Positioning Using a Grid Attached to a Spring Bow for a Custom Ocular Prosthesis. J Clin Diagn Res 2017;11:ZD12-ZD13.  Back to cited text no. 8
    
9.
Peyman GA, Sanders DR, Goldberg MF, editors. Principles and practice of ophthalmology. Philadelphia: Saunders Limited; 1980.  Back to cited text no. 9
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]



 

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