Fabrication of Customised Esthetic Acrylic Ocular Prosthesis

INTRODUCTION

The loss of the facial structures can have a physical, social and psychological impact on those affected . Loss of structure can be either due to trauma or congenital. An eye is generally the first feature to be noticed. Treatment of such cases includes implants and acrylic eye prosthesis. A custom-made ocular prosthesis is a good alternative.

The main purpose of maxillofacial prostheses which restore and replace stomatognathic and associated facial structures with artificial substitutes is to improve the patient’s esthetics, restore and maintain health of the remaining structures and consequently provide physical and mental well being.

ESTHETIC AND PSYCHOLOGICAL EFFECTS :

The prime requisite of such patients is early and satisfactory restoration of the lost tissues to their normal anatomic form. A prosthetic replacement is the treatment of choice to return the individual to his normal vocation by producing an acceptable and life - like appearance.

OBJECTIVES OF MAXILLOFACIAL REHABILITATION

STEPS IN FABRICATION OF OCULAR PROSTHESIS 1,2,3

• A proper diagnosis , treatment planning should be done along with proper history and assessment of prognosis.

• Ocular conformer has to be made with clear acrylic with a piece of plastic tube in between and adjusted to the size of the eye socket to record the socket dimension and conform the impression material (fig : 3 ).
• A thin mix of irreversible hydrocolloid can be used to make impression (fig : 5 ).
• 2.5ml syringe is to be used to inject impression material into the inlet (fig : 4 ).
• Patient has to be seated at an angulation of 45° to the floor so that normal positioning of palpebra and against gravity is allowed.
• Patient has to be asked to move the eye up and down so that excess impression material flows out.
• Patient has to look straight in front , so that impression material will record back region.
• A putty index is then made on the impression recorded and the impression material within the index is replaced with wax ( fig : 6 ,7,8 ).
• Wax pattern is tried within the socket of the patients orbit and adjusted till the desired volume and comfort is attained (fig : 9 ,13 ).
• According to Beumer , Distance from midline to pupil =30mm, Between two pupils=60mm, from inner canthus of eye to sclera=5mm is adjusted using a digital calliper (fig : 10 ,11 ).
• Iris conformer is to be used to adjust conversational gaze (fig : 12 ).
• The wax pattern is then flasked, cured and characterised (fig : 14 ,15 ,19 ).
• Acrylic is to be cured for 8 hrs and more to prevent any residual monomer and thus irritation.
• Porosity is reduced if the resin is processed at 150° F for 9 hours followed by 212 ° F for 2 hours.

CASE REPORT 1

A 49 Year old patient reported to the department of prosthodontics with the chief complaint of small size and improper colour of the existing eye prosthesis .

Problems analysed:

• Small sized appearance of the left eye.
• Failure of the previous treatment as it was unsuccessful in correcting the ptosis of the upper eyelid.
• Improper impression made.
• Improper wax trial.

Improper colour matching with the existing natural eye.

CASE REPORT 2

A 60 Year old patient reported to the department of prosthodontics with the chief complaint of missing left eye which was lost due to trauma 10yrs back.

Characterisation 1,4

• One of the method of painting is to use oil paint or dry earth pigments into painting medium called as monopoly.
• Monopoly is a syrup of poly methyl methacrylate with 10 parts of heat cure acrylic resin monomer with 1 part of clear acrylic resin polymer by weight.
• When a colour is selected , it is mixed with one or two drops of heat cured monomer and to this mixture a smaller amount of monopoly is added.
• Adding more monomer to the mix will increase the painting time.

Fig 17 : Sequences in fabricating eye prosthesis

DISCUSSION :

A custom sclera shell is an ultra thin cover protecting the sensitivity of the damaged eye that has loss of vision, and is a protective cover against environmental debris. It also maintains the natural opening in balance with the opposite eye. The goal of any ocular prosthetic procedure is to return the patient to the society with a normal appearance and reasonable motility of the prosthetic eye. Acrylic eye is easy to fit and adjust, unbreakable, inert to ocular fluids, esthetically good, long lasting and easier to fabricate.

Persistent ptosis requires modification of the ocular prosthesis to correct for the deficient levator muscle, which causes the upper eyelid to droop. Comparing the palpebral fissure with the patients natural eye can aid in determining the correct tray size to use for impression. To insert the tray, lift the upper eyelid, grasp the tray by the handle and slip it in, behind the upper eyelid. Release the upper lid , pull the lower lid down , insert the inferior border of the tray into the lower lid fornix and then release the lower lid4.

The lost eye lid can also be replaced with eye lid prosthesis fabricated by using silicone. It is also possible t o incorporate eyelashes with natural appearance. Illusion of eye lashes can be obtained by dark extrinsic stain dotted along the upper eyelid, artificial eyelashes require thinning and they have limited shelf life. It was also seen that natural hair could be inserted to the eyelids so that they had a longer shelf life and a more natural appearence3,5 (Fig:22 )

Fig 22 : Eyelid prosthesis

The advantages of the acrylic ocular prosthesis are as follows :

CONCLUSION

Maxillofacial rehabilitation is always challenging and it is a blend of art and science . Esthetics with ocular prosthesis can be well achieved with acrylic alone or with a combination with RTV silicone, along with proper characterisation and techniques. Proper fit , retention and esthetics along with simulation of eye movements will give psychological comfort and satisfaction for the patient.

REFERENCES