Suture-free DLEK preserves corneal
surface topography and ensures faster wound healing
Ana Hildalgo-Simón MD, PhD
endothelial keratoplasty (DLEK) eliminates corneal surface incisions
and results in faster wound healing, smoother topography and a more
stable eye by using an air bubble to re-attach the tissues after
corneal transplants, Mark A. Terry MD told a session of Cornea 2002.
Mark A. Terry MD
“We sometimes define ‘success’ after corneal transplantation
as an eye with 20/20 vision after the operation. This may be the
case, but the complications which may occur at later stages, such
as globe rupture after minor trauma, may render this ‘success’
a long-term failure,” he explained.
Dr Terry pointed out that postoperative surface irregularities after
PK can be avoided by transplanting only the posterior cornea and
that complications related to sutures can be avoided by using a
corneal suture-free procedure.
Deep lamellar endothelial keratoplasty (DLEK) is a technique used
to replace the entire corneal endothelium through a limbal scleral
tunnel incision. It avoids using any corneal surface incisions or
sutures and preserves the corneal surface from limbus to limbus.
The adhesion of tissues is initially caused by the physical hydrophilic
attraction of the wet posterior graft tissue to the wet recipient
stromal tissue, created by an air bubble in the anterior chamber.
After some minutes the air bubble is removed and it is the biological
endothelial pump mechanisms that maintain the adhesion.
The main advantage of this technique is the preservation of the
normal corneal topography. In addition, wound healing is faster
and stronger and suture-related problems such as induced astigmatism,
unpredictable corneal power, infections, ulcerations and suture-induced
visualisation with subsequent graft rejection are all avoided.
On the down side, this procedure is relatively difficult to perform
and it is a challenge for the surgeons to consistently obtain an
optically pure interface.
Dr Terry presented a summary of the basic surgical steps. The 9.0
mm scleral incision is performed with a guarded diamond knife set
at a depth of 0.35 mm, parallel to the limbus and 1.0 mm to 2.0
mm peripheral to it.
Healon is then injected through a stab incision at the 10 o’clock
position into the anterior chamber to maintain adequate pressure.
A mid to deep corneal pocket is formed from limbus to limbus. The
surgeons use the specialised Devers dissectors, switching from straight
to curved as necessary.
Healon is released from the anterior chamber through the stab incision.
Trephination of the posterior disc of the recipient is done with
a specialised intralameller 8.0 mm Terry Trephine until the anterior
chamber has been found.
The posterior disc trephination is completed with the specialised
intracorneal Cindy scissors and the disc is removed. The Healon
is completely aspirated from the anterior chamber and the interface,
and replaced with a balanced salt solution (BSS).
“This is extremely important because leaving Healon here can
prevent adhesion of your donor disc later,” he warned.
The donor cornea-scleral tissue is placed onto an artificial anterior
chamber where the donor posterior button is prepared. The chamber
is a specialised device that allows a donor cornea-scleral cap of
tissue to be anatomically positioned just as it would be in a whole
eye. This allows the surgeon the latitude to use eye bank corneas
rather than whole eyes. Either an automated microkeratome or manual
resection can be performed to remove the anterior donor stroma and
isolate the posterior donor tissue.
The donor tissue is then mounted on a punch block and the same size
(8.0 mm) donor trephine is used to punch out the posterior donor
The disc is placed (endothelial side down) onto a specialised Ousley
insertion spatula previously coated with Healon. You need to make
absolutely sure that a layer of Healon is protecting your endothelial
layer, he stressed.
After filling the anterior chamber of the recipient with air, the
donor disc is placed into the pocket, into the anterior chamber
and then lifted anteriorly into the posterior stromal recipient
The surgeon needs to hold it in position for three or four seconds
and then gently slide the spatula out of the eye, leaving the disc
in place, he explained.
Air is immediately injected into the anterior chamber to secure
the graft. The donor disc position can then be gently adjusted and
any air in the interface is removed.
The scleral wound is then closed using five or six 10-O nylon sutures.
air in the anterior chamber is completely removed. By this time
the biological response is taking over and the tissue will stay
attached. Finally, the conjunctiva is also closed and a collagen
shield with antibiotics and steroids is placed on the eye. The eye
is patched and the patch removed the next day.
Dr Terry and his research associate, Paula Ousley, now have patients
who were operated on with this technique three years ago and are
now doing very well. In their first 40 patients the average change
in astigmatism is less than 1.0 D and central corneal power does
not change at all.
The average vision at one year is 20/50. He added that despite good
initial results, several factors are needed to be taken into account
when assessing these results.
“First, the average age of the patients treated with this
procedure is quite advanced. It was 78 years in my initial 40 patients
series. The number of non-related eye pathologies that reduce vision
are considerable. Second, there is a learning curve and results
will improve with time as the surgeon becomes more skilled in the
procedure,” he said.
His results represent a 100% follow-up. No patients dropped out
because of infection, ruptured globes or other complications present
in more traditional techniques, he stressed. Dr Terry founded and
leads the Endothelial Keratoplasty Group, which consists of 35 US
sites and 15 international ones, to scientifically investigate and
advance DLEK surgery.
A. Terry MD
Devers Eye Institute, Portland, Oregon, US