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 Procedure > Custom Fit Trial Shell, Phase I > Custom Fit Scleral Shell, Phase II  
 

Procedure for Fitting Phase II: Impression Moulded Scleral Ocular Prosthesis
(For the Acquired Dysfunctional or Phthisical Globe)

Congratulations on your double accomplishment of completing the wearing schedule for Phase I Scleral Trial Shell for the prescribed time (your waking hours), and mastering the technique of inserting and removing the shell.  We can now describe the procedure involved in fabricating the Phase II Scleral Ocular Prosthesis.

Laboratory Sessions:  The amount of time required to duplicate the iris color striations is dependent upon the thinness of the trial shell at the selected cornea/pupil apex.  Since, our objective is to use as much of the anterior-posterior thickness for a clear acrylic cornea to obtain a lifelike 3-dimensional effect.  Therefore, the scleral trial shell (thickness) measurement will determine which of the following methods is appropriate for duplicating the iris color.

Method 1:  Surface Iris Painting

Visit #1 (Estimated Duration: 1 hour)

If it is a thin scleral shell measures less than 1½ millimeters (no loss of global volume), a duplicate of the trial shell would be made in white acrylic.  (1st curing cycle)

Visit #2 (Estimated Duration: 2-3 hours)

A circle would then be scribed on the white scleral shell for iris diameter and pupil center.  The entire anterior surface would be trimmed down to ¼ millimeter.  The iris painting would then be painted together with scleral tints and simulation of the vascular pattern.  A clear acrylic overlay would then be applied to replace the white acrylic that had been trimmed away.  (2nd curing cycle)  Another option, providing this was only a scarred, disfigured cornea, would be to utilize your own sclera by now trimming away most of the white acrylic from the posterior side of the shell.  This would be replaced with clear acrylic (3rd curing cycle).

Method 2:  Curved Iris-Cornea Die Plate

Visit #1 (Estimated Duration: 1½ hour)

If the thin scleral shell measures 1½ to 2½ millimeters it would be marked for pupil/iris center with an attached plastic stem.  (A two piece mold would be made of the scleral trial shell.)  A specially designed curved iris-cornea die-plate would be used for the iris painting.  This technique involves placing an aluminum foil over the curved surface and painting on its surface.  When a clear acrylic mixture is compressed (1st curing cycle) and cured under heat and pressure, the painted iris will become the posterior surface of the clear acrylic cornea.  The iris cornea would then be embedded in a white acrylic mixture (2nd curing cycle).

Visit #2 (Estimated Duration: 45 minutes to 1 hour)

This entails the simulation of the scleral tints and vascular pattern (white portion of the eye).  The iris is exposed to the desired iris diameter.  (Red nylon and cotton threads are applied in varying thickness to create the 'bloodshot' appearance, and various tints are added to simulate the scleral tones.  A clear acrylic overlay would then be applied to replace the white acrylic that had been trimmed away.  (3rd curing cycle)

Method 3:  Flat Acrylic Iris Disc

Visit #1 (Estimated Duration: 1 hour)

If the scleral trial shell measures more the 2½ millimeters at pupil center, it would be marked for pupil/iris center with an attached plastic stem.  (A two piece dental stone mold would be made of the scleral shell.)  A flat iris disc would be selected with the proper pupil size and placed on a tapered spindle for the painting.  The completed iris artwork is then placed in an iris-cornea die plate for a clear acrylic polymerization with an attached stem at its apex.  (1st curing cycle), followed by its being embedded in white plastic in the two piece mold made from the trial shell.  (2nd curing cycle)

Visit #2 (Estimated Duration: 45 minutes to 1 hour)

This session entails the simulation of the scleral tints and vascularization (white portion of the eye).  This is accomplished by first exposing the embedded iris-cornea surface to the desired iris diameter.  Red nylon and cotton threads are applied in varying thickness to simulate the vascular pattern, and various tints are added to match the scleral tones.  Upon completion this phase will require a clear acrylic overlay (which replaces the amount of white acrylic that was removed to expose the iris) under a controlled heat and pressure curing cycle.  (3rd curing cycle)

Final Visit for all three options: (Estimated Duration: 45 minutes to 1 hour)

The final session would be the fitting of the completed impression moulded scleral ocular prosthesis.  We would then review the insertion and removal techniques, and stress again the need for good hygiene care of eye, lids and prosthesis.

A follow-up session is then scheduled for 4 to 6 weeks to check for comfort, fit and cosmesis.  It is advisable to make notes of any questions you need answered, or any wearing problems you may have experienced in the interim.

 

 

   
   
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Jahrling Ocular Prosthetics, Incorporated
50 Staniford Street, Boston, MA  02114, USA
Members American Society of Ocularists, Board Certified Ocularists