The Bala Asymmetric Cornea Vacuum Punch?is a single-use, sterile vacuum cornea punch used to size and shape accurately a DMEK graft for effective intraoperative tissue manipulation and orientation.
When the punch is received it will be in a sterile tray sealed with a Tyvek lid. The sealed tray is housed in a cardboard carton along with printed instructions. The tray contains a vacuum syringe, the cutting block, and top blade assembly.
The Tyvek lid should be removed by an assistant and the punch emptied from the tray onto a sterile field. The punch should not be touched by the assistant.
The punch top and cutting block are separated by a ring that prevents the blade from contacting the block during shipment. The parts are held together with an elastic silicone band that should be removed after the components are taken out of the tray.
The instructions below will refer to the components as identified in the photo.
Before clinical use, the surgeon should thoroughly understand all aspects of the surgical procedure and the use of the Bala Asymmetric Cornea Vacuum Punch?. The Punch is packaged in a hermetically-sealed tray that has been gas sterilized with ethylene oxide. It is a disposable unit designed for single-use and should not be re-sterilized or reused. The punch has been carefully checked before packaging and is ready for use when it is received. The Bala Asymmetric Cornea Vacuum Punch?should be used only by a licensed physician who is familiar with corneal DMEK surgery and with the use of this instrument. The following instructions do not include all the procedural steps required to perform corneal transplant surgery.
- The size of the punch blade is marked on both the top of the punch top and the side of the cutting block as indicated in the photo at the right (the marked numbers are circled in red). Verify the blade diameter and remove the elastic silicone band from the instrument.
- While holding the cutting block with one hand, use the other hand to pull the punch top straight upward, turn it over, and place it on a sterile tray. Discard the white blade protector ring that is used to separate the punch top from the cutting block.
- Prepare the donor tissue by dissecting Descemet?s membrane (DM) from the anterior stroma. When fully dissected, reassemble the layers. Note: Orientation of the tissue along the long axis of the cornea may be helpful for ease of dissection and pedicle placement
- Place the cutting block base on a solid, flat surface.
- Fully depress the syringe plunger and hold.
- Place the reassembled donor cornea graft, endothelial surface up, in the well of the cutting block. Center the donor cornea in the well. Ensure fluid is removed from the DM – endothelial interface and the graft lies smoothly and wrinkle-free in the well prior to punching.
- Quickly and fully release the plunger of the vacuum syringe. The graft will be secured in the well.
- Insert the four steel guideposts of the trephine blade housing assembly into the corresponding holes in each corner of the cutting block base.
- View the cutting edge of the blade from above and ensure it overlaps the graft. If overlap is inadequate, remove the blade, depress the plunger to release vacuum, reposition the graft, and repeat steps 4, 5, 6, and 7.
- Once the graft position is satisfactory, place your thumb over the trephine blade housing assembly and, in a circular manner, gently press down or tap blade housing assembly until it has cut the Descemet endothelial complex and entered the stroma. A full thickness cut through the donor tissue stroma is not recommended.
- While holding the cutting block base with one hand, pull trephine housing assembly upward with the other hand to separate components.
- Maintain vacuum, do not depress the plunger of the syringe.
- Stain the graft lightly with trypan blue to help visualize the cut edge. If necessary, break adhesions with a spatula or Vannas scissors. Remove the peripheral Descemet?s-endothelial rim and discard.
- While holding the cutting block base with one hand, use non-toothed forceps to grasp the graft pedicle at the base (near the attachment to the central tissue) and peel the remaining circular graft from the stroma.
- Return separated graft tissue back into the cutting block well, stain with pigment and load into the injector.
The following video created by Dr. Chandra Bala of Australia demonstrates a technique for using the Bala Asymmetric Cornea Punch?.