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March 2018
investigators found that the OLCR
device outperformed the PCI device
using the Olsen formula, which also
ranked first for both short and long
eyes.
5
Finally, a study that included
more than 13,000 cataract surgeries
using monofocal IOLs revealed that
the Olsen method was more than
80% within 0.5 D, while most other
formulas did worse. Error versus
axial length showed ray tracing
outcomes to be among the best com-
pared to other formulas, especially
in long eyes.
6
Fellow eye
"We saw in almost 400 eyes that
there is a correlation coefficient of
roughly 0.9 between the error of the
left and right eyes. If you take the
difference between the right and left
IOL position, you will get more than
95% within ±0.25 mm. This is even
better than what I can predict from
preop data. That means I can use the
observed IOL position in the first eye
in the planning for the second eye,"
Dr. Olsen explained, referring to his
study that tested the hypothesis that
the refractive outcomes of the first
eye could be used to improve the
IOL power calculation of the second
eye.
7
EW
References
1. Olsen T, et al. Ray-tracing analysis of the
corneal power from Scheimpflug data. J
Refract Surg. 2018;34:45–50.
2. Olsen T, et al. Ray-tracing analysis of intra-
ocular lens power in situ. J Cataract Refract
Surg. 2012;38:641–7.
3. Olsen T, et al. C constant: new concept
for ray tracing-assisted intraocular lens
power calculation. J Cataract Refract Surg.
2014;40:764–73.
4. Cooke DL, et al. Comparison of 9 intraocular
lens power calculation formulas. J Cataract
Refract Surg. 2016;42:1157–64.
5. Cooke DL, et al. Prediction accuracy of
preinstalled formulas on 2 optical biometers. J
Cataract Refract Surg. 2016;42:358–62.
6. Melles RB, et al. Accuracy of intraocular
lens calculation formulas. Ophthalmology.
2018;125:169–178.
7. Olsen T. Use of fellow eye data in the calcu-
lation of intraocular lens power for the second
eye. Ophthalmology. 2011;118:1710–5.
Editors' note: Dr. Olsen has finan-
cial interests with Haag-Streit and
PhacoOptics (Aarhus, Denmark).
Contact information
Olsen: t@olsen.dk
