1. Corneal Spherical Aberration in a Population of Patients Measured by 3 Different Instruments
Mohamed A Guenena, MD
Helga P Sandoval, MD, MSCR
Kerry D Solomon, MD
Magill Research Center for Vision Correction, Storm Eye Institute
Medical University of South Carolina, Charleston
The authors does not have any financial interests in the products mentioned

2. Background
Spherical aberration (SA) is a fourth-order higher-order aberration in which peripheral light rays are refracted more than the central ones
Can be positive or negative depending on where the light rays focuses
Leads to image spread on the retina instead of point focus
Average cornea SA is +.27µ compensated by the lens negative SA in healthy individuals.
After cataract surgery, if a spherical IOL is implanted, it will add more positive SA to the eye

3. Background
Several aspheric monofocal IOLs have been developed with different SA values to compensate for the corneal SA
Tecnis Z µ
AcrySof SN60WF -.20µ
nanoFLEX Collamer -.019µ
Sofport AO
Tecnis
SN60WF
Sofport AO
nanoFLEX

4. Background
Literature suggests getting the patient closest to 0 SA to achieve the optimum quality of vision
Correct selection of the aspheric IOLs will depend mainly on SA measurements of the cornea

5. Purpose
To compare the measurements of corneal spherical aberration obtained by the Atlas Corneal Topography (Carl Zeiss, Jena, Germany), Galilei Dual Scheimpflug Analyzer (Ziemer, Port, Switzerland) and the OPD-Scan II (Nidek, Tokyo, Japan).
Atlas Corneal Topography
Galilei Dual Scheimpflug Analyzer
OPD-Scan II

6. Methods
A pilot study
SA were measured in patients undergoing cataract surgery before dilation.
SA measured in the 6 mm optical zone
No history of ocular surgery or injury
No ocular pathology other than cataract
All measurements were done by single trained observer
Difference between measurements were analyzed

7. Methods Reports from the 3 tested instruments

8. Measurements
8 eyes of 6 patients All females Average age: 73 years ( 63-81)
Atlas
Galilei
OPD
Eye 1
0.226
0.37
0.267
Eye 2
0.274
0.25
0.129
Eye 3
0.094
0.18
0.206
Eye 4
0.3
0.217
Eye 5
0.341
0.29
0.255
Eye 6
0.266
0.28
Eye 7
0.285
0.27
0.261
Eye 8
0.161
0.31
0.169
Average
0.220
(± 0.05)
0.281
0.228
(± 0.08)

9. Difference between Galilei and OPD measurements compared to Atlas
Galilei - Atlas
OPD-Atlas
Eye 1
0.041
0.144
Eye 2
-0.145
-0.024
Eye 3
0.112
0.086
Eye 4
0.037
0.12
Eye 5
-0.086
-0.051
Eye 6
-0.011
0.014
Eye 7
-0.015
Eye 8
0.008
0.149
Average
-0.009
(± 0.079)
0.053
(± 0.081)
Positive sign = overestimate
Negative sign = underestimate

10. Conclusion
This pilot study showed high consistency of measurements of SA among the 3 tested instruments
This finding can help the surgeons choose the proper aspheric IOL regardless of which measuring instrument is used.
More studies are needed to determine the optimal SA surgeons need to target

11. Thank you