Abstract
Purpose
To investigate the accuracy of intraocular lens power calculations using simulated keratometry (simK) of dual Scheimpflug analyzer and 5 types of formulas in cataract patients.
Methods
The keratometry (K), axial length (AXL) and anterior chamber depth (ACD) were measured using ultrasound biometry (USB) combined with auto-keratometry (Auto-K), parital coherence interferometry (PCI; IOL master®) and dual Scheimpflug analyzer (DSA; Galilei®) in 39 eyes of 39 patients. Predicted refraction was calculated using Auto-K, mean K of PCI, and simK and total corneal power (TCP) of DSA in the Sanders-Retzlaff-Kraff (SRK-T) formula. The SRK-II, SRK-T, Holladay II, Haigis, and Hoffer-Q formula were used to calculate predicted refraction with the simK of DSA and AXL of USB. Manifest refraction, mean numerical error (MNE) and mean absolute error were evaluated 1, 3 and 6 months after cataract surgery.
Results
TCP of DSA was lower compared with other keratometric values (p < 0.05). The MNE was not different among Auto-K, mean K and simK. The MNE using TCP was larger compared with Auto-K, mean K and simK at 1 month after surgery (p < 0.05). There was a difference in MNE between simK and TCP of DSA at 6 months after surgery (p < 0.05). The MNE of SRK-T formula was the smallest in the intraocular lens (IOL) power calculation using the simK of DSA.
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Table 1.
PCI | USB-Auto K | DSA-simK | DSA-TCP | p-value | |
---|---|---|---|---|---|
AXL (mm) | 23.04 ± 0.79 | 23.08 ± 0.72 | − | − | 0.289 |
ACD (mm) | 3.02 ± 0.48 | 3.03 ± 0.49 | 3.04 ± 0.50 | − | 0.822 |
Mean K (diopter) | 44.51 ± 1.59 | 44.38 ± 1.52 | 44.42 ± 1.53 | 43.07 ± 1.98* | <0.001† |
Table 2.
PCI | USB | DSA-simK | DSA-TCP | p-value | |
---|---|---|---|---|---|
1 month after surgery | |||||
MNE (D) | −0.01 ± 0.25 | −0.06 ± 0.26 | −0.06 ± 0.30 | 0.46 ± 1.28 | 0.001* |
MAE (D) | 0.14 ± 0.18 | 0.17 ± 0.20 | 0.22 ± 0.22 | 0.93 ± 1.01 | |
No. of MAE < 0.5 D (%) | 36 (90.0%) | 34 (85.0%) | 32 (80.0%) | 21 (52.5%) | 0.000† |
No. of MAE < 1.0 D (%) | 39 (100.0%) | 39 (100.0%) | 39 (100.0%) | 27 (67.5%) | 0.000† |
6 months after surgery | |||||
MNE (D) | 0.04 ± 0.59 | 0.07 ± 0.56 | −0.02 ± 0.53 | 0.29 ± 0.79 | 0.471 |
MAE (D) | 0.40 ± 0.34 | 0.42 ± 0.31 | 0.38 ± 0.31 | 0.63 ± 0.55 | |
No. of MAE <0.5 D (%) | 12 (63.2%) | 13 (68.4%) | 14 (78.9%) | 7 (43.8%) | 0.181 |
No. of MAE <1.0 D (%) | 17 (89.5%) | 18 (94.7%) | 18 (94.7%) | 12 (75.0%) | 0.212 |