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
cross-hairs 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 of 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
the 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 (zero position).
Retract the blade a full revolution by turning
the white spokes
on top of the
blade assembly (4 spokes) to prevent the blade from touching the surface of the eye.
If the blade is
not retracted
vacuum will not
be obtained.
Moisten the anterior corneal surface with balanced salt solution.
Push in the plunger of the syringe all the way and hold.
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 plastic spokes on top of
the blade assembly clockwise
(as viewed from the top of
the trephine) one full
revolution (4 spokes) to
return
the blade to the zero position.
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.
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.
CAUTION:
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.
Note:
Some users have developed their technique so that the entire recipient cut is made with the
trephine. However, this procedure should 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
to bind.
If the epithelium is loose or bullous, most surgeons remove it prior to application of the
trephine.
An example of the use of the Hessburg-Barron Vacuum Trephine
is shown in the Flash Video at the right which was prepared
by Dr. Irving Raber of
Keystone Eye Associates. The original video can be found
at
Eyetube.net
