Ocular Prosthesis- Eye with an Art

Debasish De, Bachelor of Optometry

Optometrist, Dr. Shroff’s Charity Eye Hospital, New Delhi.

 

The face is the portrait of the mind, the eyes, its informers.

It is said that ‘eyes are the ‘windows to the soul. Loss or absence of any part of the face can cause severe physical and psychological trauma. ⁽¹⁾ The eyes are the most noticeable structure on the face,⁽²⁾ and their loss causes a psychological fragility of patients.⁽³⁾ The absence of eye may be congenital ⁽⁴⁾ or acquired due to surgical removal which can be indicated in several cases such as traumas,⁽⁵⁾ cancer, painful blind eye, and suprachoroidal haemorrhage etc.⁽⁶⁾

Depending on the severity, surgical management includes one of the three approaches: enucleation, evisceration, or exenteration.⁽⁷⁾ There are several materials and techniques in the literature for the fabrication of ocular prosthesis. It may be using a stock eye, modifying stock eye, or fully customized ocular prosthesis.

Procedure

• Impression – To provide a custom ocular prosthesis, an accurate impression of the socket is to be obtained.The socket is cleaned of discharge and secretions and lubricated with few drops of tears substitute and an impression plastic tray is chosen according to the size of the eye socket. Next, the impression tray is placed in the patient eye socket and a mixture of alginate is inserted into the syringe and is injected into the eye socket to produce a definitive impression (Fig.1).

 

Figure1: Steps of taking impression with the mixture of Alginate powder. For preparing the impression into a wax model, the impression tray is dipped into a mixture of alginate powder and the carving wax is heated and poured into the impression to create a wax model then the alginate mixture is opened, and an exact wax replica of the socket impression is created. The wax model is then smoothened (Fig 2).

Figure 2: Preparation of wax model.

• Iris button diameter (Fig.3) is chosen according to the measurement of the iris and corneal diameter of the patient’s fellow eye. An initial painting is done on the button by matching the colour with the other eye.

Figure. 3: Painted Iris button.

• The wax model is re-inserted into the patient’s eye socket (Fig. 4) to check for the fitting, movement and centration is marked using a marker by comparing it with the corneal light reflex of the fellow eye.

Figure 4: Wax model inserted into patient’s eye socket.

• Once the wax model is finished, mould is prepared using mould flask and dental stone (Fig. 5).

Figure 5: Preparation of mould.

• Fabrication of the acrylic model is done with PMMA mixed with monomer to make dough and kept under autoclave for polymerization for one and half hour (Fig. 6) at a starting temperature of 60 c gradually going up to 100 c and upon reaching .It is maintained at that temperature for rest of the time.

Figure 6: Demonstrates the fabrication process.

• Once polymerized then the Front and back surface of the model are trimmed and polished to smoothen the surface using brown wax (Fig. 7.).

 Figure 7: Polishing of the front and back surface of the prosthesis.

• Final painting is done by matching it with the colour of normal eye of the patient (Fig. 8).

Figure 8: Colouring of sclera.

• Clear coating is given with PMMA and monomer mixture and again polymerised for 1 hr(Fig. 9) at the temperature starting at 60 degree.

Figure 9: Application of clear coating with PMMA and monomer mixture.

• After polymerization, the prosthesis is then trimmed and polished to smoothen the surface and for shining (Fig.10).

 Figure10: Trimming & polishing process of the Prosthesis.

• Final COP is fitted in the patient eye socket for checking fitting and movements. Insertion and removal is taught to the patient (Fig. 11).

Figure 11: Final prosthesis polished and fitted.

Human eyes have highly complex structure which is difficult to mimic. COP’s has many advantages over stock eye like, better colour matching, more coordinated movements. Success of ocular prosthesis mainly depends on the precision, knowledge, and artistic skills of the clinician.

 

 References

1. Cain JR. Custom ocular prosthetics. J Prosthet Dent 1982;48(6):
   690–694. DOI: 10.1016/S0022-3913(82)80030-9.
2. Pathak C, Pawah S, Singh G, et al. Prosthetic rehabilitation of completely blind subject with bilateral customised ocular prosthesis: a case report. J Clin Diagn Res. 2017 Jan;11(1):ZD06–ZD08
3. Zheng C, Wu AY. Enucleation versus evisceration in ocular trauma:a retrospective review and study of current literature. Orbit. 2013 Dec;32(6):356–361.
4. Bermejo E, Martínez-Frías ML. Congenital eye malformations: clinical epidemiological analysis of 1,124,654 consecutive births in Spain. Am J Med Genet. 1998 Feb 17;75(5):497–504.
5. Goiato MC, Mancuso DN, Sundefeld MLMM, et al. Aesthetic and functional ocular rehabilitation. Oral Oncology Extra. 2005;41 (8):162–164.
6. Nakra T, Simon GJ, Douglas RS, et al. Comparing outcomes of enucleation and evisceration. Ophthalmology. 2006 Dec;113(12):2270–2275.
7. Parr GR, Goldman BM, Rahn AO. Surgical considerations in the prosthetic treatment of ocular and orbital defects. J Prosthet Dent 1983;49(3):379–385. DOI: 10.1016/0022-3913(83)90281-0.