OCULUS Pentacam Interpretation Manual page 147

20 Total corneal astigmatism for toric IOL
Figure 171: Corneal Power Distribution display showing a lower amount of astigmatism,
at 0.6 D 114.9°
The choice of the IOL was between the SN6AT3 and the SN6AT4 models (the T2 model was not
available). According to the manufacturer, the SN6AT3 and the SN6AT4 should correct, respectively,
1.03 and 1.55 D at the corneal plane. After including the effect of surgically induced astigmatism
(0.2 D 90°), calculations based on meridional analysis [49], which, unlike the manufacturer online
calculator, take into consideration the effect of axial length and corneal power [50], suggested a T4
IOL to correct the KA (residual predicted astigmatism = 0.23 D 39°) and a T3 IOL to correct the TCRP
astigmatism (residual predicted astigmatism = 0.20 D 36°). We decided to implant the T3 model in
order to correct the TCRP astigmatism. The IOL was oriented at 115° and the patient's refraction at
one month after surgery revealed no residual refractive cylinder: the refractive outcome showed that
our choice to rely on TCA had been correct.
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