1. Hôpital Ophtalmique Universitaire
Jules Gonin
Relationship of Corneal Diameter and Horizontal Ciliary Sulcus in Eyes Prior to ICL Implantation
ID: 12944
Ivo Guber, MD, Ciara Bergin, PhD, Sylvie Perritaz, Optom, François Majo, MD, PhD
Medical and Surgical Cornea, Refractive Surgery, Contact lenses and Eye banking
Jules-Gonin Eye Hospital, Lausanne, Switzerland
The authors have no financial interests to disclose.

2. IMPLANTABLE COLLAMER LENS
Phakic posterior chamber intraocular lens
Collagen polymer
Treatment of high ametropia
Retains the biostructure of the cornea
Safer option in terms of RD for high myopia than clear lens extraction
Retains the ability of accomodation

3. VAULTING
The Vaulting is the distance between ICL and the cristalline lens.
The fit of the ICL determines the postoperative vault, the ICL choice is determined by
ACD
WTW
Ciliary sulcus diameter
Insufficient vaulting is the main risk factor for cataract formation after ICL implantation, more accurate ICL sizing is required

4. STUDY AIM
To estimate the repeatability of horizontal ciliary sulcus (HCS) diameter as measured with the HiScan UBM. Next, to report the agreement with HCS and horizontal white-to-white (HWTW) diameter as measured with the Pentacam and BioGraph. Combining this information to form a conversion table between devices to help the clinician in their choice of ICL sizing.

5. STUDY DESIGN This is a retrospective study.
All records of patients who were assessed for ICL implantation were reviewed.
Those eyes with Pentacam, BioGraph and HiScan data available were included in analysis.
The average of between 4 and 6 measures of HCS were used as part of the patient assessment; this data was used to examine repeatability of the UBM.
The agreement, bias and correlation between the average HCS and the HWTW estimates were also calculated.

6. METHODS
(A) Pentacam Scheimpflug image no 17/25 at 183° with the interior corneal sceral transition delinated (B) BioGraph iris photo with limbus border out lined (C) HiScan 50Hz UBM image with HCS (green line) and ACD (red line)

7. PATIENT CHARACTERISTICS
Parameter
SE >-6.0D
SE -6D-10D
SE< -10.0D
Group
Number of eyes 17 40 50
107 SE
+1.90 (4.16)
-8.52 (1.16)
(5.69)
-8.93 (5.69) AL
22.80 (1.56)
26.8 (0.97)
27.88 (2.15)
26.67 (2.44)
ACD
3.05 (0.22)
3.26 (0.26)
3.14 (0.23)
3.17 (0.25)
IOP
14.6 (1.9)
15.5(2.9)
16.1 (2.3)
15.6 (2.5)
HWTW Pentacam
11.91 (0.48)
12.00(0.53)
11.73(0.47)
11.86 (0.52)
HWTW BioGraph
12.08 (0.43)
12.36 (0.49)
11.93 (0.47)
12.12 (0.51)
HCS UBM
10.77 (0.48)
11.19 (0.57)
10.81 (0.53)
10.95(0.56)
VCS UBM*
11.31(0.48)
Mean spherical equivalent was -8.9D, SD ±5.67D. The HWTW measures taken with the BioGraph were wider than those taken with the Pentacam (bias= 0.26mm, p<0.01) and both HWTW measures were wider than the HCS measures (bias >0.91mm, p<0.01).

8. RESULTS
Bland-Altman plot of the repeatability of HCS measures using the HiScan UBM, open symbols show the agreement between any two HCS measures the limits of agreement are given with dotted horizontal lines, closed symbols give the agreement between the average of pairs of measures, the limits of agreement are given with a solid line.

9. RESULTS
The agreement between the devices was examined using Bland Altman plots, limits of agreement and Pearson correlation coefficients. The HWTW measures as taken with the Pentacam and the BioGraph showed good agreement (г=0.73) with some systematic bias (-0.26mm) and relatively tight limits of agreement (95% CI -0.93, +0.41). Comparing the HWTW of the Pentacam with the HCS measure of the UBM showed moderate agreement (г=0.54) with a large systematic bias (0.91mm) with wide limits of agreement (95% CI -0.15, 1.97). Comparing the HWTW of the BioGraph with the HCS measure of the UBM showed moderate agreement (г=0.64) with a larger systematic bias (1.17mm) with wide limits of agreement (95% CI +0.26, 2.07). The agreement between the ACD measures was better between BioGraph and Pentacam than between these two devices and UBM (г=0.99 vs г=0.88/0.87).

10. RESULTS – Conversion table
Study results summary
Bias SD
Pentacam vs BioGraph
HWTW vs HWTW
-0.26
0.34
Pentacam vs UBM
HWTW vs HCS
0.91
0.54
BioGraph vs UBM
1.17
0.46
From Orbscan estimate to «Device » estimate
Bias estimates
(Reference)
Sample size
Suggested bias correction
UBM
Artemis 50 mHz
-0.89(2)
-0.58(35) 50
-0.74
Hiscan 35 Mhz
-0.39(24)
-0.71(17)
-0.42(16) 31 20 28
-0.48
Vumax 35 Mhz
0.46(18) 37
0.46
UBM Quantel medical 50Mhz
0.14(34) 63
0.14
Humphrey's UBM 840 (50MHz)**
0.46(13, 36, 37)
(100,10,72)
Carl Zeiss mHz
0.40(22)
129
0.40
Scheimpflug image
Pentacam
0.43(Guber)
117
0.43
Iris camera
0.1 (38)
101
0.1
Gaillei
0.34 (39) 74
0.34
Eyesys
0.42 (39)
0.42
Eyemetrics
0.18 (40) 73
0.18
IOL Master
0.50(41)
0.24 (36)
0.47(18)
0.22 (42)
0.33 (43)
328
100 40 52
0.41
Biograph/Lenstar
0.48(37)
0.69(Guber) 72
0.57
Calipers
0.11(36)
0.01(37)
0.07
Holladay-Godwin gauge
0.02 (36)
0.02
RESULTS – Conversion table

11. CONVERSION 12.05mm +0.48mm 12.53mm +0.57mm 13.10mm Diff +1.05mm
Suggested bias correction
Orbscan ↓
device
Device
UBM
Artemis 50 mHz
-0.74
0.74
Hiscan 35 Mhz
-0.48
0.48
Vumax 35 Mhz
+0.46
-0.46
UBM Quantel medical 50Mhz
0.14
-0.14
Humphrey's UBM 840 (50MHz)**
0.46
Carl Zeiss mHz
0.40
-0.40
Scheimpflug image
Pentacam
0.43
-0.43
Iris camera
0.1
-0.1
Gaillei
0.34
-0.34
Eyesys
0.42
-0.42
Eyemetrics
0.18
-0.18
IOL Master
0.41
-0.41
Biograph/Lenstar
0.57
-0.57
Manual
Calipers
0.07
-0.07
Holladay-Godwin gauge
0.02
-0.02
Hiscan
12.05mm
+0.48mm
Orbscan
12.53mm
+0.57mm
Biograph
13.10mm
Diff mm
= 2 ICL sizes

12. CONCLUSIONS
The ICL is the most commonly used phakic intraocular lens in the United States, however in order to conform to the FDA accepted guidelines it is essential that clinicians are aware and account for bias between devices used for ICL sizing by
Using conversion table provided or
Providing details of the device used in order that STAAR adjust accordingly
When using UBM estimates of the HCS to estimate the ICL size:
The average of repeated measures should be used to compensate for the poor repeatability
Careful attention should be payed to which device was used to develop HCS specific ICL sizing nomograms
The relationship between HWTW and HCS is stronger than reported.