Transcript PowerPoint 프레젠테이션 - ASCRS/ASOA 2009

Comparison of Central Corneal
Thickness measured by
Four methods in normal
and Post-IntraLASIK eyes
Hyun Ju Lee, M.D., Suk Kyue Choi, M.D.,
Do Hyung Lee, M.D., Ph.D., Jin Hyoung Kim, M.D.
Department of Ophthalmology, Ilsan Paik Hospital, Inje
University College of Medicine, Gyeonggi, Korea
Authors have no financial interest
PURPOSE
 To compare corneal pachymetry assessment
using four measurement methods in normal eyes
and Post-IntraLASIK eyes
METHODS
 Corneal pachymetry assessment using
1. Ultrasonic pachymetry
(Advent, Mentor O&O, Norwell, MA, USA )
- Default velocity : 1641 (m/s)
2. Scanning slit topography
(Orbscan II; Bausch & Lomb, Rochester,NY)
- Acoustic equivalent correction factor : 0.95
3. Rotating Scheimpflug Camera
(Pentacam; Oculus Inc, Wetzlar, Germany)
4. Dual Scheimpflug Analyzer
(GALILEI™; Ziemer)
METHODS
 Group I
- 30 unoperated eyes
(Unoperated group)
 Group II
- 30 eyes : shorter than 6 months after IntraLASIK
(Early postoperative IntraLASIK group)
 Group III
- 30 eyes : longer than 7months after IntraLASIK
(Late postoperative IntraLASIK group)
RESULTS
Corneal Thickness Measurement
Mean±SD (um)
Group
Galilei
Pentacam
Ultrasound
Orbscan
P Value
I
554±30.3
544±30.7
541±31.3
535±40.7
0.202
II
488±30.1
479±28.6
475±32.1
440±40.3
.000
III
483±32.9
472±33.3
470±33.3
432±51.7
.000
One-Way ANOVA
 Group I, the four measurements were similar with a mean difference
within 18.4 μm. (P=.202)
 Group II & III, Orbscan were thinner than other mesurements. (P=.000)
RESULTS
Corneal Thickness Measurement
Group and Measurement
Group
I
Group
II
Group
III
U-G
U-P
U-O
U-G
U-P
U-O
U-G
U-P
U-O
Mean differnece
(um)
95% Limit of
Agreement
P Value
Pearson Correlation
(R) (p < 0.001)
-12.3
-2.7
6.1
-13.2
-4.1
34.4
-12.8
-2.4
37.8
-34.9, 10.2
-25.3, 19.9
-16.51, 28.62
-35.5, 9.0
-26.4, 18.2
12.1, 56.7
-38.9, 13.2
-28.5, 23.6
11.7, 63.8
0.487
0.989
0.897
0.412
0.964
0.001
0.573
0.995
0.001
0.982
0.984
0.932
0.983
0.980
0.903
0.972
0.977
0.918
G = Galilei, P = Pentacam, U = Ultrasound, O = Orbscan II
ANOVA, Scheffe multiple comparison test
 Group II & III, Compared to the ultrasound measurement, orbscan
significantly underestimated the corneal thickness. (P=.001)
RESULTS
Corneal Thickness Measurement
Group and Measurement
Group
U-O
Mean differnece
(um)
95% Limit of
Agreement
P Value
I - II
-28.4
-41.2,-15.5
.000
I - III
-31.7
-44.6, 18.8
.000
II - III
-3.3
-16.2, 9.5
0.812
U = Ultrasound, O = Orbscan II
ANOVA, Scheffe multiple comparison test
Bland-Altman plots comparing
the 4 modalities (Group I)
Group I
Group I
40.00
Group I
40.00
40.00
12.3
0.7 (-1.96 SD)
0.00
-20.00
-40.00
20.00
13.4 (+1.96 SD)
2.7
0.00
-8.1 (-1.96 SD)
-20.00
-40.00
500.00
600.00
Average of Galilei & US
Difference (Orbscan - US)
Difference (Galilei - US)
20.00
Difference (Pentacam - US)
25.5 (+1.96 SD)
23.8 (+1.96 SD)
20.00
-6.1
0.00
-20.00
-37.6 (-1.96 SD)
-40.00
-60.00
-80.00
500.00
600.00
Average of Pentacam & US
500.00
600.00
Average of Orbscan & US
 Group I, all four methods showed good agreement, with a mean difference
being within ± 20 um.
Bland-Altman plots comparing
the 4 modalities (Group II)
Group II
Group II
Difference (Galilei - US)
24.9 (+1.96 SD)
20.00
13.2
1.5 (-1.96 SD)
0.00
-20.00
-40.00
40.00
17.8 (+1.96 SD)
20.00
4.1
0.00
-9.6 (-1.96 SD)
-20.00
-40.00
300.00
400.00
500.00
Average of Galilei & US
600.00
Difference (Orbscan - US)
40.00
Difference (Pencatam - US)
40.00
Group II
20.00
0.5 (+1.96 SD)
0.00
-20.00
-34.4
-40.00
-60.00
-69.3 (-1.96 SD)
-80.00
300.00
400.00
500.00
Average of Pentacam & US
600.00
300.00
400.00
500.00
Average of Orbscan & US
 Group II, galilei and pentacam showed good agreement with ultrasound, with
a mean difference being within ± 10 um.
 Group II, the limits of agreement between orbsan and ultrasound were 0.5 um
and – 69.3 um with a range of 69.8 um.
600.00
Bland-Altman plots comparing
the 4 modalities (Group III)
Group III
Group III
40.00
Group III
40.00
40.00
12.8
-2.3 (-1.96 SD)
0.00
-20.00
-40.00
20.00
16.3 (+1.96 SD)
20.00
2.4
0.00
-11.5 (-1.96 SD)
-20.00
500.00
Average of Galilei & US
600.00
11.1 (+1.96 SD)
0.00
-20.00
-37.7
-40.00
-60.00
-86.5 (-1.96 SD)
-80.00
-100.00
-40.00
400.00
Difference (Orbscan - US)
20.00
Difference (Pentacam - US)
Difference (Galilei - US)
27.9 (+1.96 SD)
-120.00
400.00
500.00
Average of Pentacam & US
600.00
400.00
500.00
600.00
Average of Orbscan & US
 Group III, galilei and pentacam showed good agreement with ultrasound,
with a mean difference being within ± 10 um.
 Group III, the limits of agreement between orbsan and ultrasound were 11.1 um
and – 86.5 um with a range of 97.6 um.
RESULTS
 Group I (CCT)
- Similar for all four methods (P=.202)
 Group II, III (CCT)
- No statistically significant difference among Galilei,
Pentacam and Ultrasound
- Orbscan measurements were thinner than other
mesurements
 After IntraLASIK, Galilei & Pentacam was comparable to
Ultrasound(current gold standard for corneal pachymetry)
 Orbscan measurement of CCT after refractive surgery are
less than those measured by US
DISCUSSION
 CCT using Galilei and Pentacam before and after
IntraLASIK is also suitable
 CCT using orbscan tends to be underestimated
compared with other values after refractive
surgery (Group II & III )
 Further studies are needed to determined which
instrument is more accurate in measuring CCT