Transcript Document

Post-Mortem Ultra-Structural Analysis of a
Cornea Transplanted With DMEK
Jack Parker Jr, MD; Eitan Livny, MD; Vasilis S. Liarakos, MD, PhD;
Gerrit R. Melles, MD, PhD
The Netherlands Institute for Innovative Ocular Surgery (NIIOS),
Melles Cornea Clinic, and the Amnitrans Eye Bank,
Rotterdam, The Netherlands.
*No authors have any financial interests to disclose
Background (1/2)
After Descemet Membrane Endothelial Keratoplasty
(DMEK), the cornea of the transplanted eye looks
essentially “normal,” virtually indistinguishable from
a healthy, unoperated eye when viewed by slit-lamp
biomicroscopy…
3 months after DMEK for Fuchs
Endothelial Dystrophy
Background (2/2)
…However, in operations where we’ve had to replace a “failed”
DMEK graft, we’ve observed that performing the Descemetorhexis is
significantly more challenging than in a virgin eye. Seemingly, the
donor DMEK graft “sticks” more firmly the recipient posterior
stroma than does normal endothelium.
As a result, we began to wonder:
1)
Ultra-structurally (under high power microscopes with
special tissue stains) does eyes with DMEK grafts really look
indistinguishable from a normal, unoperated eyes
2)
What explains this extra observed “stickiness” that DMEK
grafts appear to have?
3)
Might an explanation for this “stickiness” shed new light on
the cause (and prevention of) DMEK’s most common
complication – graft detachment?
Experimental Design
To investigate these matters, we harvested the whole
globe of a deceased patient formerly operated with a
DMEK for Fuchs Endothelial Dystrophy (FED).
The Patient: 76 year old white female, who received
her DMEK previously at the Netherlands Institute for
Innovative Ocular Surgery (NIIOS)
The tissue: The cornea was removed, sectioned, and
sent for light and transmission electron microscopy
After DMEK, before Death (1/2)
Six months after the patient’s DMEK, the transplanted cornea was thin and clear,
resulting in a best corrected distance visual acuity of 20/25 (0.8). Anterior segment
optical coherence tomography (A), slit-lamp (B, ), and Pentacam images (C)
After DMEK, before Death (1/2)
Two years after surgery
(at the last clinic visit
before the death) the
cornea remained thin and
clear with a healthy
appearing endothelial cell
population, essentially
identical to a normal,
unoperated eye. Vision
was stable at 20/28 (0.7)
Slit-lamp (A) and specular
microscopy (B)
images
Results: Light Microscopy after Death
Light microscopy image of the
patient’s cornea 2 years after
DMEK. No identifiable scar tissue
or inflammatory reaction is seen
at the donor-to-host interface.
Note the bridging collagen fibers
connecting the host’s stroma to
the donor’s DM (arrows).
[The separation of the donor DM
from the host posterior stroma is
an artifact induced by tissue
processing for light microscopy]
Results: Light Microscopy after Death
Light microscopy of
the edge of the
DMEK graft. No scar
or hypertrophic
tissue or an overlap
of the graft and the
central rim of the
descemetorhexis
could be identified,
and the graft edge
appears similar to
more central areas
Results: Transmission Electron
Microscopy (TEM) after Death
Transmission electron microscopy of the patient’s cornea 2 years after DMEK (A) and of a healthy naïve eye (B). Junction
between donor DM and host stroma. Note the close attachment of the interfacial matrix of the donor DM to the host
stroma and the projection of stromal collagen fibrils into the interfacial matrix (arrows). Fibril projection depth is 6400 nm
(dashed bar). Note that the ultrastructure of the DMEK graft-to-stroma junction is virtually indistinguishable from the
normal DM-to-stromal junction in a naive cornea. ABL, anterior banded layer of the DM; IFM, interfacial matrix; ST, stroma
host; the arrowhead points to longspacing collagen fibers (bar = 500 nm).
Discussion
• Ultra-structurally, the DMEK graft looked identical to a normal,
unoperated corneal endothelium, without any additional (or absent)
identifiable structures
• The additional observed “stickiness” observed when stripping a failed
DMEK graft from the posterior corneal surface may stem from:
1. Deeper projection of collagen fibrils into the DM
2. Larger number of linking collagen fibrils,
3. Higher concentration of adhesion molecules as occasionally seen in
naive corneas
4. Other adhesion structures such as peg-like interdigitations of the
interfacial matrix into the host stroma that were not seen
Conclusion
• DMEK seems to accurately restore the cornea’s
normal anatomy
• The absence of identifiable scar tissue at the graft
interface may explain the unprecedented visual
outcomes of the operation
Thank you!
Jack Parker
[email protected]
Gerrit Melles
[email protected]
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