The Hessburg-Barron Vacuum Trephine? is comprised of the trephine assembly, which is connected to a vacuum syringe via a small silicone tubing with a color-coded Luer-Lok hub. Codes can be found at the bottom of the page. The hub should not be disconnected, but if for some reason it is found necessary to do so, care should be taken when re-attaching it because the silicone tubing projects into the hub and can be pinched when attaching the hub to the syringe.
The trephine assembly consists of a blade that is secured in a threaded spoke adapter having a thread pitch of 0.25 mm. The blade contains crosshairs to help the surgeon align the blade with the center of the desired cut. The spoke adapter screws into a body subassembly that consists of a threaded plastic piece with finger grips and a vacuum body that is used to secure the trephine onto the cornea during cutting.
The spoke adapter should not be removed from the plastic body subassembly as it can be difficult to realign the threads.
Important: The Hessburg-Barron Vacuum Trephine? is a disposable instrument that has been sterilized with ethylene oxide. It should not be re-sterilized or reused. Do not disassemble the trephine or remove the hub from the syringe. Each trephine is tested prior to packaging and is ready for use when it is received by the surgeon.
Suggestions for use
The Hessburg-Barron Vacuum Trephine? should only be used by a licensed physician who is familiar with corneal transplant surgery and with the use of this instrument. The following instructions do not include all the procedural steps required to perform corneal transplant surgery.
- Dry the anterior corneal surface with a cellulose sponge. Mark the center of the desired cut on the recipient cornea with a sterile gentian violet marking pen.
- Examine trephine under the operating microscope and turn the white plastic spokes on top of the blade assembly until the edge of the blade is aligned with the inner wall of the vacuum chamber (reference position).? Verify the blade diameter that is marked on the top of the plastic rim of the blade assembly.
- Retract the blade at least two full revolutions by turning the white spokes on top of the blade assembly (8 spokes) counterclockwise as viewed from the top. This is done to prevent the blade from touching the surface of the eye when the trephine is placed on the cornea.? If the blade is not retracted, vacuum will not be obtained.
- Moisten the anterior corneal surface with a balanced salt solution.
- Grasp the white plastic finger grips between the thumb and index finger of the non-dominant hand, and while looking through the center of the trephine with the operating microscope, align the cross hairs with the visual centration mark on the recipient cornea.
- Press the trephine evenly on the anterior corneal surface and release the plunger of the syringe abruptly. Test if vacuum has been obtained and is adequately holding the cornea against the trephine.
- Confirm that the trephine is in the correct position.
- Stabilize the trephine by lightly holding it with the thumb and index finger of the non-dominant hand. Do not squeeze or tilt the trephine.
- With the index finger of the dominant hand, turn the spokes of the blade assembly clockwise until the blade contacts the cornea. Note that the shape of the cornea and the precision of setting the reference position will determine the amount of clockwise movement needed to contact the cornea.
- To commence cutting, continue to advance the blade by turning the white plastic spokes clockwise. For each complete revolution (4 spokes), the blade is lowered 0.25 mm.
- When the desired depth of cut has been reached, release the vacuum by pushing in the plunger of the syringe. Remove the trephine from the cornea.
- For penetrating keratoplasty, complete the cut in the usual manner.
Once the cornea is perforated with the trephine, the blade should not be lowered further and the trephine should immediately be removed from the eye.
- Some users have developed their technique for penetrating keratoplastty so that the entire recipient cut is made with the trephine. However, this procedure should be done with extreme caution.
- When cutting, hold the trephine lightly between the thumb and finger, and as low as possible. Holding the trephine with excessive force could cause the spoke adapter and body subassembly threads to bind.
- If the epithelium is loose or bullous, most surgeons remove it prior to application of the trephine.
Color Code for Trephine Hubs
|Light Blue||7.25 mm|
|Dark Blue||8.0 mm|