DSAEK

Report
Alteration in disc diameter after
DSAEK
Takefumi YAMAGUCHI,Yoshiyuki SATAKE, Seika DEN,
Kenji KONOMI, Jun SHIMAZAKI
Tokyo Dental College, Ichikawa General Hospital,
Chiba, Japan
The authors have no financial interest.
Introduction
Descemet’s stripping and automated endothelial
keratoplasty (DSAEK) is treatment of first choice for
bullous keratopathy. Total number of endothelial cells
transplanted is important in maintaining sufficient number
of endothelial cells after DSAEK. However, whether larger
disc preferable remains unknown. If so, how large a disc can
be safely transplanted? Herein we conducted the study on
the disc structure after DSAEK.
Purpose
To evaluate alteration in disc diameter and structure after
DSAEK.
Patients
This study comprised 15 eyes in 15 patients who
underwent DSAEK at Tokyo Dental College
Women: 12 eyes; Men: 3 eyes
Surgical technique (no. of eyes)
Age +/- SD: 69.3 +/-12.6 years DSAEK: 9
Causes of bullous keratopathy (no.of eyes)
Laser iridotomy: 7
Cataract surgery: 5
Fuchs’endothelial dystrophy: 2
Pseudoexfoliation syndrome: 1
DSAEK+PEA+IOL: 5
DSAEK+TS IOL suturing: 1
(TS: transscleral)
Disc diameter 8 mm: 14
(no. of eyes) 7.75 mm: 1
Graft preparation
All grafts were imported from
Sight Life Eye Bank (Northwest)
and prepared using Barron’s
corneal punch during surgery.
Methods
 Data on disc diameter, central graft anterior chamber depth#1 and
central and peripheral graft thickness were obtained using anterior
segment optical coherence tomography (AS-OCT, CASIA, SS-1000,
Tomey, Japan) at 1 and 3 months after DSAEK.
 Measurements were performed manually under refractive correction in
4 directions: horizontal, vertical, 45 and 135 degrees.
G-ACD
GD
#1 Graft anterior chamber depth (G-ACD) was
defined as distance between apex of posterior surface
of graft and line connecting inner graft edges.
Where large decentration of graft position was
observed, data were excluded from study.
GD: Graft diameter, G-ACD: graft anterior chamber
Results
Visual acuity
3500
2
Endothelial cell count
3000
LogMAR
1.5
2500
2000
1
1500
1000
0.5
500
0
0
Preop
1m
3m
Preop
1m
Graft anterior chamber(G-ACD)=1.50±0.19 μm, Central graft thickness (CGT)=121±30.1 μm
Peripheral graft thickness(PGT)=235±101 μm, Angle to angle distance (AD)=11.7±0.58 mm
3m
Average disc diameter
(mm) 8
Horizon
tal
Vertical
GD
7.8
7.6
Disc diameter shrank in all
4 directions (mm: no. of
eyes out of 11 eyes#1):
0.10 < : 9 (81%)
0.25 < : 7 (64%)
0.40 < : 5 (46%)
#1 Number of patients on whom accurate data
obtained in all 4 directions with no obstruction by
lid or cilia.
7.4
Preop
1m
GD: Graft diameter
3m
Effect of graft decentration
Possible measurement error caused by decentration
from center of graft during measurement.
(vertical)
Distance between O and O’: x (mm)
Largest amount of graft shrinkage
in 4 directions: S (mm)
θ = ∠O’OA
S is maxim value if θ is 22.5°
If S is below 0.10 mm, x >0.12614 mm
θ O’Graft center
If S is below 0.25 mm, x > 0.3013 mm
= (mm)
O:Measurement center If S is below 0.40 mm, x > 0.462751mm
A
(135)
D
(horizontal)
B
B’
oo’ x
C’
(45)
C
A’
D’
In measuring length and width, there is a high
possibility that decentration will cause the graft to
appear smaller than it actually is.
Taking measurements in all four directions lowers
the margin of error.
Relation between GD and G-ACD
y = 0.2693x - 0.5641
R² = 0.1826
1.8
P=0.0012
G-ACD
2
1.6
1.4
1.2
1
6.5
7
7.5
GD
8
8.5
GD: Graft diameter, G-ACD: graft anterior chamber
GD was significantly correlated with G-ACD.
(Pearson’s correlation analysis).
This result indicates that G-ACD /GD ratio did
not change in various eyes after DSAEK, which
suggests the posterior surface curvature (flat or
steep) did not influence the GD.
Is larger disc preferable?
Advantage
・More endothelial cells can be transplanted.
Disadvantage
・Possible decrease in endothelial cells due to manipulation of
large disc during surgery.
However, there are two important PREMISES
⇒Slightly shrinks
① Graft size does not change after DSAEK.
② Endothelial cells will distribute equally throughout host and graft
surface.
Discussion
Endothelial cell loss after DSAEK has been reported to be 20-50%.
Area calculated from parameters of model eye
Posterior corneal surface(ACD2.8 mm): approx.110 mm2
Posterior surface of disc of 8 mm:
approx.55 mm2
120
Area of posterior corneal surface
Surface area
100
80
60
40
20
0
7
7.5
8
8.5
9
9.5 10
Disc diameter (2c)
11
S=π(c2+h2), c: radius,
h: height, h=r-√r2-c2,
r: curvature of posterior corneal
surface, r = 6.8 mm
Discussion
If disc shrinks by around 0.25 mm after DSAEK, it might be
possible to transplant larger disc or customize disc diameter using
preoperative values of AS-OCT such as angle-to-angle distance or
anterior chamber depth in each patient.
(We call this AS OCT-assisted DSAEK)
If endothelial cells distribute equally on host and graft cornea after
DSAEK, endothelial cell loss in previous studies can not be
explained based on calculation of posterior surface area. It is
possible that endothelial cell “privilege” in DSAEK graft prevents
equal redistribution of endothelial cells after DSAEK. More
comprehensive and long-term evaluation, including central and
peripheral endothelial cell counts, graft edge configuration and
chromosome assessment in graft and host cornea, will yield
invaluable information on this issue.
Conclusion
 Disc diameter tended to shrink from 1 month after DSAEK,
stabilizing at 3 months.
 In some patients, large alteration in disc diameter observed,
suggesting larger disc is preferable in some cases. However,
postoperative endothelial cell redistribution on host and graft
cornea must be evaluated in future.

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