Amar Agarwal |
Descemet’s membrane is a vital layer of the cornea, and any damage
to the endothelial cells can lead to endothelial decompensation. This can occur
primarily as part of Fuchs’ dystrophy or secondary to surgical trauma. The
most common cause of surgical trauma is cataract surgery and consequent aphakic
or pseudophakic bullous keratopathy.
Although many patients with pseudophakic bullous keratopathy have the
IOL well-placed in the bag or sulcus, one can also come across a number of
patients who have had complicated eye surgery that results in insufficient
capsular support and inability to place an in-the-bag or sulcus-supported IOL.
These patients are most commonly implanted with an anterior chamber IOL or a
sutured scleral-fixated IOL, or they are left aphakic. A rarer presentation is
one in which a posterior chamber IOL has been placed in the anterior chamber
either accidentally or intentionally, resulting in consequent corneal
decompensation.
Patients with an anterior chamber IOL or a posterior chamber IOL
misplaced in the anterior chamber or aphakic patients with bullous keratopathy
need secondary IOL implantation combined with corneal transplantation in the
form of penetrating or lamellar keratoplasty. Descemet’s membrane
endothelial keratoplasty was first described by Gerrit Melles, and we first
described glued IOLs in 2007. We would now like to describe a new combined
procedure wherein lamellar keratoplasty in the form of DMEK is combined with
secondary IOL implantation using the glued IOL technique.
Graft preparation
The basic technique consists of preparing the donor graft by partially
trephining it and then using a Sinskey hook to lift up the edge of the cut
Descemet’s membrane. Once an adequate edge is lifted, non-toothed forceps
are used to gently grab Descemet’s membrane at its very edge, and the
graft is separated from the underlying stroma in a capsulorrhexis-like
circumferential manner. It is then stained with trypan blue and replaced in the
sterile corneal storage medium while the recipient eye is prepared.
DMEK with glued IOL
An anterior chamber maintainer is inserted, and two points are marked on
the sclera exactly 180° apart. Two 2.5 mm x 2.5 mm lamellar scleral flaps
are created on either side, centered on the marks. Trypan blue is used to stain
the patient’s Descemet’s membrane before scoring and stripping it,
approximately 8.5 mm in diameter (as marked from above the corneal surface)
using a reverse Sinskey hook. A 20-gauge needle is used to create a sclerotomy
about 1 mm to 1.5 mm from the limbus under each scleral flap, and a 23-gauge
vitrector introduced through the sclerotomy is used to perform anterior
vitrectomy.
In case of a posterior chamber IOL in the anterior chamber (Figure 1),
the IOL is repositioned in a closed globe manner by exteriorizing its haptics
through the sclerotomies (Figures 2a and 2b). In case of an anterior chamber
IOL, the IOL is explanted and a new IOL is implanted by performing the
conventional glued IOL technique. In aphakic eyes, a foldable IOL is injected
into the anterior chamber and its haptics are exteriorized through the
sclerotomy. In all situations, once both haptics are exteriorized, the
Scharioth tuck is employed to tuck them into scleral tunnels made at the edge
of the scleral flaps using a 26 gauge needle. Intracameral pilocarpine is used
to constrict the pupil and, if necessary, a pupilloplasty is performed.
 Figure 1. Preop pseudophakic bullous keratopathy. Note:
Posterior chamber IOL implanted in the anterior chamber. |
 Figure 2a. Posterior chamber IOL implanted in anterior chamber
leading to corneal decompensation. The same posterior chamber IOL is being
relocated into the posterior chamber using a closed globe glued IOL technique.
The haptic is grabbed from over the iris using end-gripping MST forceps and,
using a handshake technique, is transferred between the two hands until the tip
of the haptic is held. |
 Figure 2b. The haptic is exteriorized through the sclerotomy
made under the scleral flap. The same procedure is followed for the second
haptic, which is exteriorized through a sclerotomy under a second scleral flap
created 180° away from the first. Each haptic is then tucked into a scleral
tunnel created at the edge of the scleral flap. |
 Figure 3. The DMEK graft is unrolled, and an air bubble is used
to appose it against the overlying stroma. Images: Agarwal A |
The graft is carefully loaded into a STAAR ICL injector with the
cartridge tip held occluded with a finger. It is then injected gently into the
anterior chamber by plunging the soft-tipped injector, taking care not to fold
the graft. Wound-assisted implantation is avoided, and the anterior chamber
maintainer flow is titrated carefully to prevent backflow and extrusion of the
graft through the incision. The graft orientation is checked, and the graft is
unfolded gently using a small air bubble, as described by Melles. Once
unfolded, an adequately tight air bubble is injected under the graft to float
it up against the stroma (Figure 3). Interface fluid is milked out through
pre-placed sutures. Tisseel fibrin glue (Baxter) is used to seal the lamellar
scleral flaps, conjunctiva and clear corneal incisions.
This technique combines the advantages of stable fixation of the IOL as
well as the advantages of lamellar keratoplasty. In contrast, an anterior
chamber IOL has the disadvantage of decreased IOL-endothelial distance, which
can cause long-term graft failure when combined with penetrating keratoplasty.
It becomes especially disadvantageous when combined with Descemet’s
stripping endothelial keratoplasty, in which the endothelium with donor stroma
also occupies space within the anterior chamber, thereby bringing the anterior
surface of the anterior chamber IOL very close to the DSEK lenticule. Hence,
these patients need explantation of the anterior chamber IOL with secondary IOL
fixation and corneal transplantation.
Sutured scleral-fixated IOLs can be combined with endothelial
keratoplasty, but they have the disadvantage of a longer open-sky period,
making the eye more vulnerable to potential complications such as expulsive
hemorrhage. There is also more pseudophakodonesis associated with sutured IOLs
because the fixation to the sclera is via sutures at two points, whereas in the
glued IOL technique, the haptic of the IOL is anchored to the sclera along a
significant portion of its length. This stability of the glued IOL can, in our
opinion, lead to a decreased rate of graft dislocation as compared with a
sutured scleral-fixated IOL, which has more intraocular mobility. The glued IOL
also offers the ability to adjust the centration of the IOL at any time during
surgery by simply adjusting the degree of tuck of the haptics into the scleral
tunnel, unlike the longer and more tedious procedure that would be required to
re-center a decentered sutured scleral-fixated IOL. All suture-related
complications such as erosion, degradation and exposure are also eliminated.
The fibrin glue seals the flaps hermetically over the haptics and makes the
procedure safe. Another problem in endothelial keratoplasty in aphakic eyes
with deficient capsules is the chance of the graft falling into the vitreous.
This is avoided with the combination of DMEK and the glued IOL technique.
Conclusion
In our opinion, the glued IOL combined with DMEK offers the ability to
secondarily fixate the IOL as well as perform endothelial keratoplasty in a
safe and effective manner. Greater evolution in the preferred technique of
endothelial keratoplasty, on which extensive research is under way in major
international centers, is looked forward to in order to further increase the
long-term success rate of the corneal graft.
- Amar Agarwal, MS, FRCS, FRCOphth, is director of Dr. Agarwal’s
Eye Hospital and Eye Research Centre. Prof. Agarwal is the author of several
books published by SLACK Incorporated, publisher of Ocular Surgery
News, including Phaco Nightmares: Conquering Cataract
Catastrophes, Bimanual Phaco: Mastering the Phakonit/MICS
Technique, Dry Eye: A Practical Guide to Ocular Surface Disorders
and Stem Cell Surgery and Presbyopia: A Surgical Textbook.
He can be reached at 19 Cathedral Road, Chennai 600 086, India; fax:
91-44-28115871; email: dragarwal@vsnl.com; website:
www.dragarwal.com.
- Disclosure: Dr. Agarwal is a consultant for STAAR Surgical.