Extending single-plate implants

Answer:

When additional drainage is required some years after implantation of an implant one option is to add extra drainage area to the existing bleb by placing an additional implant in an adjacent quadrant of the eye. This can be done without actually entering the eye itself again.

The new implant is positioned in a suitable adjacent quadrant, rotated so that it's tube faces the original implant and the plate attached to the eye through the (now) anterior suture holes . After tying a 5.0 Vicryl ligature around the tube the tube of the new implant is inserted into the centre of the existing (original) bleb cavity through the side of the existing thick bleb wall.  In this instance when the tube is trimmed to the right length, the tip of the tube is beveled so that the bevel faces downwards.

 We call this a "piggy-back' procedure.  It is a very safe and effective way of increasing the drainage area.   A new Molteno3-175mm implant is the recommended choice for the extra drainage. Alternatively a single plate Molteno (code S1) could be used.

Surgical instructions for this procedure are available here.